WorldWideScience

Sample records for sub-earth sized planets

  1. AN ANCIENT EXTRASOLAR SYSTEM WITH FIVE SUB-EARTH-SIZE PLANETS

    Energy Technology Data Exchange (ETDEWEB)

    Campante, T. L.; Davies, G. R.; Chaplin, W. J.; Handberg, R. [School of Physics and Astronomy, University of Birmingham, Edgbaston, Birmingham B15 2TT (United Kingdom); Barclay, T.; Huber, D.; Burke, C. J.; Quintana, E. V. [NASA Ames Research Center, Moffett Field, CA 94035 (United States); Swift, J. J. [Department of Astronomy and Department of Planetary Science, California Institute of Technology, MC 249-17, Pasadena, CA 91125 (United States); Adibekyan, V. Zh. [Centro de Astrofísica, Universidade do Porto, Rua das Estrelas, 4150-762 Porto (Portugal); Cochran, W. [Department of Astronomy and McDonald Observatory, The University of Texas at Austin, TX 78712-1205 (United States); Isaacson, H. [Astronomy Department, University of California, Berkeley, CA 94720 (United States); Silva Aguirre, V.; Christensen-Dalsgaard, J.; Metcalfe, T. S.; Bedding, T. R. [Stellar Astrophysics Centre (SAC), Department of Physics and Astronomy, Aarhus University, Ny Munkegade 120, DK-8000 Aarhus C (Denmark); Ragozzine, D. [Department of Physics and Space Sciences, Florida Institute of Technology, 150 West University Boulevard, Melbourne, FL 32901 (United States); Riddle, R. [Division of Physics, Mathematics, and Astronomy, California Institute of Technology, Pasadena, CA 91125 (United States); Baranec, C. [Institute for Astronomy, University of Hawai' i at Mānoa, Hilo, HI 96720-2700 (United States); Basu, S., E-mail: campante@bison.ph.bham.ac.uk [Department of Astronomy, Yale University, New Haven, CT 06520 (United States); and others

    2015-02-01

    The chemical composition of stars hosting small exoplanets (with radii less than four Earth radii) appears to be more diverse than that of gas-giant hosts, which tend to be metal-rich. This implies that small, including Earth-size, planets may have readily formed at earlier epochs in the universe's history when metals were more scarce. We report Kepler spacecraft observations of Kepler-444, a metal-poor Sun-like star from the old population of the Galactic thick disk and the host to a compact system of five transiting planets with sizes between those of Mercury and Venus. We validate this system as a true five-planet system orbiting the target star and provide a detailed characterization of its planetary and orbital parameters based on an analysis of the transit photometry. Kepler-444 is the densest star with detected solar-like oscillations. We use asteroseismology to directly measure a precise age of 11.2 ± 1.0 Gyr for the host star, indicating that Kepler-444 formed when the universe was less than 20% of its current age and making it the oldest known system of terrestrial-size planets. We thus show that Earth-size planets have formed throughout most of the universe's 13.8 billion year history, leaving open the possibility for the existence of ancient life in the Galaxy. The age of Kepler-444 not only suggests that thick-disk stars were among the hosts to the first Galactic planets, but may also help to pinpoint the beginning of the era of planet formation.

  2. A Hubble space telescope search for a sub-Earth-sized exoplanet in the GJ 436 system

    Energy Technology Data Exchange (ETDEWEB)

    Stevenson, Kevin B. [NASA Sagan Fellow. (United States); Bean, Jacob L.; Fabrycky, Daniel; Kreidberg, Laura, E-mail: kbs@uchicago.edu [Department of Astronomy and Astrophysics, University of Chicago, 5640 South Ellis Avenue, Chicago, IL 60637 (United States)

    2014-11-20

    The detection of small planets orbiting nearby stars is an important step toward the identification of Earth twins. In previous work using the Spitzer Space Telescope, we found evidence to support at least one sub-Earth-sized exoplanet orbiting the nearby mid-M dwarf star GJ 436. As a follow up, here we used the Hubble Space Telescope (HST) to investigate the existence of one of these candidate planets, UCF-1.01, by searching for two transit signals as it passed in front of its host star. Interpretation of the data hinges critically on correctly modeling and removing the Wide Field Camera 3 (WFC3) instrument systematics from the light curves. Building on previous HST work, we demonstrate that WFC3 analyses need to explore the use of a quadratic function to fit a visit-long time-dependent systematic. This is important for establishing absolute transit and eclipse depths in the white light curves of all transiting systems. The work presented here exemplifies this point by putatively detecting the primary transit of UCF-1.01 with the use of a linear trend. However, using a quadratic trend, we achieve a better fit to the white light curves and a reduced transit depth that is inconsistent with previous Spitzer measurements. Furthermore, quadratic trends with or without a transit model component produce comparable fits to the available data. Using extant WFC3 transit light curves for GJ 436b, we further validate the quadratic model component by achieving photon-limited model fit residuals and consistent transit depths over multiple epochs. We conclude that, when we fit for a quadratic trend, our new data contradict the prediction of a sub-Earth-sized planet orbiting GJ 436 with the size, period, and ephemeris posited from the Spitzer data by a margin of 3.1σ.

  3. A septet of Earth-sized planets

    Science.gov (United States)

    Triaud, Amaury; SPECULOOS Team; TRAPPIST-1 Team

    2017-10-01

    Understanding the astronomical requirements for life to emerge, and to persist, on a planet is one of the most important and exciting scientific endeavours, yet without empirical answers. To resolve this, multiple planets whose sizes and surface temperatures are similar to the Earth, need to be discovered. Those planets also need to possess properties enabling detailed atmospheric characterisation with forthcoming facilities, from which chemical traces produced by biological activity can in principle be identified.I will describe a dedicated search for such planets called SPECULOOS. Our first detection is the TRAPPIST-1 system. Intensive ground-based and space-based observations have revealed that at least seven planets populate this system. We measured their radii and obtained first estimates of their masses thanks to transit-timing variations. I will describe our on-going observational efforts aiming to reduce our uncertainties on the planet properties. The incident flux on the planets ranges from Mercury to Ceres, comprising the Earth, and permitting climatic comparisons between each of those worlds such as is not possible within our Solar system. All seven planets have the potential to harbour liquid water on at least a fraction of their surfaces, given some atmospheric and geological conditions.

  4. Kepler Planets Tend to Have Siblings of the Same Size

    Science.gov (United States)

    Kohler, Susanna

    2017-11-01

    After 8.5 years of observations with the Kepler space observatory, weve discovered a large number of close-in, tightly-spaced, multiple-planet systems orbiting distant stars. In the process, weve learned a lot about the properties about these systems and discovered some unexpected behavior. A new study explores one of the properties that has surprised us: planets of the same size tend to live together.Orbital architectures for 25 of the authors multiplanet systems. The dots are sized according to the planets relative radii and colored according to mass. Planets of similar sizes and masses tend to live together in the same system. [Millholland et al. 2017]Ordering of SystemsFrom Keplers observations of extrasolar multiplanet systems, we have seen that the sizes of planets in a given system arent completely random. Systems that contain a large planet, for example, are more likely to contain additional large planets rather than additional planets of random size. So though there is a large spread in the radii weve observed for transiting exoplanets, the spread within any given multiplanet system tends to be much smaller.This odd behavior has led us to ask whether this clustering occurs not just for radius, but also for mass. Since the multiplanet systems discovered by Kepler most often contain super-Earths and mini-Neptunes, which have an extremely large spread in densities, the fact that two such planets have similar radii does not guarantee that they have similar masses.If planets dont cluster in mass within a system, this would raise the question of why planets coordinate only their radii within a given system. If they do cluster in mass, it implies that planets within the same system tend to have similar densities, potentially allowing us to predict the sizes and masses of planets we might find in a given system.Insight into MassesLed by NSF graduate research fellow Sarah Millholland, a team of scientists at Yale University used recently determined masses for

  5. The Status of Kepler's Search for Earth-size Planets

    Science.gov (United States)

    Batalha, Natalie M.; Kepler Team

    2011-05-01

    NASA's Kepler Mission uses transit photometry to determine the frequency of earth-size planets in or near the habitable zone of Sun-like stars. The photometer is a 0.95-m effective aperture, wide field of view Schmidt camera in an Earth-trailing orbit that monitors over 150,000 stars brighter than 16th magnitude in a 115 square degree field of view. The mission has had two major public data releases, providing the astronomical community with four months of nearly continuous, high-precision photometry of all stars targeted as part of the Kepler planet search. A catalog of approximately 1,000 stars with transiting planet candidates -- more than 70% of which are smaller than Neptune -- accompanied the data release (Borucki et al. 2011). As Kepler collects more data, it gains sensitivity to smaller planets at longer orbital periods. This is reflected in the catalog as it contains sizable numbers of candidates that are earth-sized as well as sizable numbers of candidates in the habitable zone. Multiple transit systems are abundant in the released data. Dynamical studies suggest that the false-positive rate for these systems will be smaller than for the general sample. Moreover, the potential for determining planet masses via transit timing variations hold much promise for confirming the smaller planet candidates. Ground-based follow-up observations, transit timing observations, and blend analyses to rule out false positives have all played a major role in establishing the planet interpretation, leading to major mission milestones such as the discovery of Kepler's first rocky planet, Kepler-10b, and the discovery of six transiting planets orbiting the same star, Kepler-11. We present an overview of the status of the mission -- its health, performance, discoveries to date, our progress in determining the frequencies of planets, and our strategies moving forward. Funding for this mission is provided by the NASA Science Mission Directorate.

  6. How Do Earth-Sized, Short-Period Planets Form?

    Science.gov (United States)

    Kohler, Susanna

    2017-08-01

    Matching theory to observation often requires creative detective work. In a new study, scientists have used a clever test to reveal clues about the birth of speedy, Earth-sized planets.Former Hot Jupiters?Artists impression of a hot Jupiter with an evaporating atmosphere. [NASA/Ames/JPL-Caltech]Among the many different types of exoplanets weve observed, one unusual category is that of ultra-short-period planets. These roughly Earth-sized planets speed around their host stars at incredible rates, with periods of less than a day.How do planets in this odd category form? One popular theory is that they were previously hot Jupiters, especially massive gas giants orbiting very close to their host stars. The close orbit caused the planets atmospheres to be stripped away, leaving behind only their dense cores.In a new study, a team of astronomers led by Joshua Winn (Princeton University) has found a clever way to test this theory.Planetary radius vs. orbital period for the authors three statistical samples (colored markers) and the broader sample of stars in the California Kepler Survey. [Winn et al. 2017]Testing MetallicitiesStars hosting hot Jupiters have an interesting quirk: they typically have metallicities that are significantly higher than an average planet-hosting star. It is speculated that this is because planets are born from the same materials as their host stars, and hot Jupiters require the presence of more metals to be able to form.Regardless of the cause of this trend, if ultra-short-period planets are in fact the solid cores of former hot Jupiters, then the two categories of planets should have hosts with the same metallicity distributions. The ultra-short-period-planet hosts should therefore also be weighted to higher metallicities than average planet-hosting stars.To test this, the authors make spectroscopic measurements and gather data for a sample of stellar hosts split into three categories:64 ultra-short-period planets (orbital period shorter than a

  7. Two Earth-sized planets orbiting Kepler-20.

    Science.gov (United States)

    Fressin, Francois; Torres, Guillermo; Rowe, Jason F; Charbonneau, David; Rogers, Leslie A; Ballard, Sarah; Batalha, Natalie M; Borucki, William J; Bryson, Stephen T; Buchhave, Lars A; Ciardi, David R; Désert, Jean-Michel; Dressing, Courtney D; Fabrycky, Daniel C; Ford, Eric B; Gautier, Thomas N; Henze, Christopher E; Holman, Matthew J; Howard, Andrew; Howell, Steve B; Jenkins, Jon M; Koch, David G; Latham, David W; Lissauer, Jack J; Marcy, Geoffrey W; Quinn, Samuel N; Ragozzine, Darin; Sasselov, Dimitar D; Seager, Sara; Barclay, Thomas; Mullally, Fergal; Seader, Shawn E; Still, Martin; Twicken, Joseph D; Thompson, Susan E; Uddin, Kamal

    2011-12-20

    Since the discovery of the first extrasolar giant planets around Sun-like stars, evolving observational capabilities have brought us closer to the detection of true Earth analogues. The size of an exoplanet can be determined when it periodically passes in front of (transits) its parent star, causing a decrease in starlight proportional to its radius. The smallest exoplanet hitherto discovered has a radius 1.42 times that of the Earth's radius (R(⊕)), and hence has 2.9 times its volume. Here we report the discovery of two planets, one Earth-sized (1.03R(⊕)) and the other smaller than the Earth (0.87R(⊕)), orbiting the star Kepler-20, which is already known to host three other, larger, transiting planets. The gravitational pull of the new planets on the parent star is too small to measure with current instrumentation. We apply a statistical method to show that the likelihood of the planetary interpretation of the transit signals is more than three orders of magnitude larger than that of the alternative hypothesis that the signals result from an eclipsing binary star. Theoretical considerations imply that these planets are rocky, with a composition of iron and silicate. The outer planet could have developed a thick water vapour atmosphere.

  8. Prevalence of Earth-size Planets Orbiting Sun-like Stars

    Science.gov (United States)

    Petigura, Erik Ardeshir

    2015-04-01

    In this thesis, I explore two topics in exoplanet science. The first is the prevalence of Earth-size planets in the Milky Way Galaxy. To determine the occurrence of planets having different sizes, orbital periods, and other properties, I conducted a survey of extrasolar planets using data collected by NASA's Kepler Space Telescope. This project involved writing new algorithms to analyze Kepler data, finding planets, and conducting follow-up work using ground-based telescopes. I found that most stars have at least one planet at or within Earth's orbit and that 26% of Sun-like stars have an Earth-size planet with an orbital period of 100 days or less. The second topic is the connection between the properties of planets and their host stars. The precise characterization of exoplanet hosts helps to bring planet properties like mass, size, and equilibrium temperature into sharper focus and probes the physical processes that form planets. I studied the abundance of carbon and oxygen in over 1000 nearby stars using optical spectra taken by the California Planet Search. I found a large range in the relative abundance of carbon and oxygen in this sample, including a handful of carbon-rich stars. I also developed a new technique called SpecMatch for extracting fundamental stellar parameters from optical spectra. SpecMatch is particularly applicable to the relatively faint planet-hosting stars discovered by Kepler.

  9. Capture of terrestrial-sized moons by gas giant planets.

    Science.gov (United States)

    Williams, Darren M

    2013-04-01

    Terrestrial moons with masses >0.1 M (symbol in text) possibly exist around extrasolar giant planets, and here we consider the energetics of how they might form. Binary-exchange capture can occur if a binary-terrestrial object (BTO) is tidally disrupted during a close encounter with a giant planet and one of the binary members is ejected while the other remains as a moon. Tidal disruption occurs readily in the deep gravity wells of giant planets; however, the large encounter velocities in the wells make binary exchange more difficult than for planets of lesser mass. In addition, successful capture favors massive binaries with large rotational velocities and small component mass ratios. Also, since the interaction tends to leave the captured moons on highly elliptical orbits, permanent capture is only possible around planets with sizable Hill spheres that are well separated from their host stars.

  10. Prevalence of Earth-size planets orbiting Sun-like stars.

    Science.gov (United States)

    Petigura, Erik A; Howard, Andrew W; Marcy, Geoffrey W

    2013-11-26

    Determining whether Earth-like planets are common or rare looms as a touchstone in the question of life in the universe. We searched for Earth-size planets that cross in front of their host stars by examining the brightness measurements of 42,000 stars from National Aeronautics and Space Administration's Kepler mission. We found 603 planets, including 10 that are Earth size ( ) and receive comparable levels of stellar energy to that of Earth (1 - 2 R[Symbol: see text] ). We account for Kepler's imperfect detectability of such planets by injecting synthetic planet-caused dimmings into the Kepler brightness measurements and recording the fraction detected. We find that 11 ± 4% of Sun-like stars harbor an Earth-size planet receiving between one and four times the stellar intensity as Earth. We also find that the occurrence of Earth-size planets is constant with increasing orbital period (P), within equal intervals of logP up to ~200 d. Extrapolating, one finds 5.7(-2.2)(+1.7)% of Sun-like stars harbor an Earth-size planet with orbital periods of 200-400 d.

  11. Prevalence of Earth-size planets orbiting Sun-like stars

    Science.gov (United States)

    Petigura, Erik A.; Howard, Andrew W.; Marcy, Geoffrey W.

    2013-01-01

    Determining whether Earth-like planets are common or rare looms as a touchstone in the question of life in the universe. We searched for Earth-size planets that cross in front of their host stars by examining the brightness measurements of 42,000 stars from National Aeronautics and Space Administration’s Kepler mission. We found 603 planets, including 10 that are Earth size () and receive comparable levels of stellar energy to that of Earth (). We account for Kepler’s imperfect detectability of such planets by injecting synthetic planet–caused dimmings into the Kepler brightness measurements and recording the fraction detected. We find that 11 ± 4% of Sun-like stars harbor an Earth-size planet receiving between one and four times the stellar intensity as Earth. We also find that the occurrence of Earth-size planets is constant with increasing orbital period (P), within equal intervals of logP up to ∼200 d. Extrapolating, one finds % of Sun-like stars harbor an Earth-size planet with orbital periods of 200–400 d. PMID:24191033

  12. An Earth-sized planet in the habitable zone of a cool star.

    Science.gov (United States)

    Quintana, Elisa V; Barclay, Thomas; Raymond, Sean N; Rowe, Jason F; Bolmont, Emeline; Caldwell, Douglas A; Howell, Steve B; Kane, Stephen R; Huber, Daniel; Crepp, Justin R; Lissauer, Jack J; Ciardi, David R; Coughlin, Jeffrey L; Everett, Mark E; Henze, Christopher E; Horch, Elliott; Isaacson, Howard; Ford, Eric B; Adams, Fred C; Still, Martin; Hunter, Roger C; Quarles, Billy; Selsis, Franck

    2014-04-18

    The quest for Earth-like planets is a major focus of current exoplanet research. Although planets that are Earth-sized and smaller have been detected, these planets reside in orbits that are too close to their host star to allow liquid water on their surfaces. We present the detection of Kepler-186f, a 1.11 ± 0.14 Earth-radius planet that is the outermost of five planets, all roughly Earth-sized, that transit a 0.47 ± 0.05 solar-radius star. The intensity and spectrum of the star's radiation place Kepler-186f in the stellar habitable zone, implying that if Kepler-186f has an Earth-like atmosphere and water at its surface, then some of this water is likely to be in liquid form.

  13. KOI-3158: The oldest known system of terrestrial-size planets

    Directory of Open Access Journals (Sweden)

    Campante T. L.

    2015-01-01

    Full Text Available The first discoveries of exoplanets around Sun-like stars have fueled efforts to find ever smaller worlds evocative of Earth and other terrestrial planets in the Solar System. While gas-giant planets appear to form preferentially around metal-rich stars, small planets (with radii less than four Earth radii can form under a wide range of metallicities. This implies that small, including Earth-size, planets may have readily formed at earlier epochs in the Universe’s history when metals were far less abundant. We report Kepler spacecraft observations of KOI-3158, a metal-poor Sun-like star from the old population of the Galactic thick disk, which hosts five planets with sizes between Mercury and Venus. We used asteroseismology to directly measure a precise age of 11.2 ± 1.0 Gyr for the host star, indicating that KOI-3158 formed when the Universe was less than 20 % of its current age and making it the oldest known system of terrestrial-size planets. We thus show that Earth-size planets have formed throughout most of the Universe’s 13.8-billion-year history, providing scope for the existence of ancient life in the Galaxy.

  14. Temperate Earth-sized planets transiting a nearby ultracool dwarf star

    Science.gov (United States)

    Gillon, Michaël; Jehin, Emmanuël; Lederer, Susan M.; Delrez, Laetitia; de Wit, Julien; Burdanov, Artem; Van Grootel, Valérie; Burgasser, Adam; Triaud, Amaury H. M. J.; Opitom, Cyrielle; Demory, Brice-Olivier; Sahu, Devendra K.; Bardalez Gagliuffi, Daniella; Magain, Pierre; Queloz, Didier

    2017-01-01

    Stellar-like objects with effective temperatures of 2700K and below are referred to as “ultracool dwarfs”1. This heterogeneous group includes both extremely low-mass stars and brown dwarfs (substellar objects not massive enough to sustain hydrogen fusion), and represents about 15% of the stellar-like objects in the vicinity of the Sun2. Based on the small masses and sizes of their protoplanetary disks3,4, core-accretion theory for ultracool dwarfs predicts a large, but heretofore undetected population of close-in terrestrial planets5, ranging from metal-rich Mercury-sized planets6 to more hospitable volatile-rich Earth-sized planets7. Here we report the discovery of three short-period Earth-sized planets transiting an ultracool dwarf star 12 parsecs away using data collected by the TRAPPIST8 telescope as part of an ongoing prototype transit survey9. The inner two planets receive four and two times the irradiation of Earth, respectively, placing them close to the inner edge of the habitable zone of the star10. Eleven orbits remain possible for the third planet based on our data, the most likely resulting in an irradiation significantly smaller than Earth's. The infrared brightness of the host star combined with its Jupiter-like size offer the possibility of thoroughly characterizing the components of this nearby planetary system. PMID:27135924

  15. HOW LOW CAN YOU GO? THE PHOTOECCENTRIC EFFECT FOR PLANETS OF VARIOUS SIZES

    Energy Technology Data Exchange (ETDEWEB)

    Price, Ellen M. [California Institute of Technology 1200 East California Boulevard, Pasadena, CA 91125 (United States); Rogers, Leslie A. [Department of Astronomy and Division of Geological and Planetary Sciences California Institute of Technology, MC249-17 1200 East California Boulevard, Pasadena, CA 91125 (United States); Johnson, John Asher [Harvard-Smithsonian Center for Astrophysics 60 Garden Street, Cambridge, MA 02138 (United States); Dawson, Rebekah I. [Department of Astronomy, University of California, Berkeley 501 Campbell Hall #3411, Berkeley, CA 94720-3411 (United States)

    2015-01-20

    It is well-known that the light curve of a transiting planet contains information about the planet's orbital period and size relative to the host star. More recently, it has been demonstrated that a tight constraint on an individual planet's eccentricity can sometimes be derived from the light curve via the ''photoeccentric effect'', the effect of a planet's eccentricity on the shape and duration of its light curve. This has only been studied for large planets and high signal-to-noise scenarios, raising the question of how well it can be measured for smaller planets or low signal-to-noise cases. We explore the limits of the photoeccentric effect over a wide range of planet parameters. The method hinges upon measuring g directly from the light curve, where g is the ratio of the planet's speed (projected on the plane of the sky) during transit to the speed expected for a circular orbit. We find that when the signal-to-noise in the measurement of g is <10, the ability to measure eccentricity with the photoeccentric effect decreases. We develop a ''rule of thumb'' that for per-point relative photometric uncertainties σ = (10{sup –3}, 10{sup –4}, 10{sup –5}), the critical values of the planet-star radius ratio are R{sub p} /R {sub *} ≈ (0.1, 0.05, 0.03) for Kepler-like 30 minute integration times. We demonstrate how to predict the best-case uncertainty in eccentricity that can be found with the photoeccentric effect for any light curve. This clears the path to study eccentricities of individual planets of various sizes in the Kepler sample and future transit surveys.

  16. An Earth-sized planet with an Earth-like density

    DEFF Research Database (Denmark)

    Pepe, Francesco; Cameron, Andrew Collier; Latham, David W.

    2013-01-01

    Recent analyses(1-4) of data from the NASA Kepler spacecraft(5) have established that planets with radii within 25 per cent of the Earth's (R-circle plus) are commonplace throughout the Galaxy, orbiting at least 16.5 per cent of Sun-like stars(1). Because these studies were sensitive to the sizes...... of the planets but not their masses, the question remains whether these Earth-sized planets are indeed similar to the Earth in bulk composition. The smallest planets for which masses have been accurately determined(6,7) are Kepler-10b (1.42R(circle plus)) and Kepler-36b (1.49R(circle plus)), which are both...... significantly larger than the Earth. Recently, the planet Kepler-78b was discovered(8) and found to have a radius of only 1.16R(circle plus). Here we report that the mass of this planet is 1.86 Earth masses. The resulting mean density of the planet is 5.57 g cm(-3), which is similar to that of the Earth...

  17. An Earth-sized planet with an Earth-like density.

    Science.gov (United States)

    Pepe, Francesco; Cameron, Andrew Collier; Latham, David W; Molinari, Emilio; Udry, Stéphane; Bonomo, Aldo S; Buchhave, Lars A; Charbonneau, David; Cosentino, Rosario; Dressing, Courtney D; Dumusque, Xavier; Figueira, Pedro; Fiorenzano, Aldo F M; Gettel, Sara; Harutyunyan, Avet; Haywood, Raphaëlle D; Horne, Keith; Lopez-Morales, Mercedes; Lovis, Christophe; Malavolta, Luca; Mayor, Michel; Micela, Giusi; Motalebi, Fatemeh; Nascimbeni, Valerio; Phillips, David; Piotto, Giampaolo; Pollacco, Don; Queloz, Didier; Rice, Ken; Sasselov, Dimitar; Ségransan, Damien; Sozzetti, Alessandro; Szentgyorgyi, Andrew; Watson, Christopher A

    2013-11-21

    Recent analyses of data from the NASA Kepler spacecraft have established that planets with radii within 25 per cent of the Earth's (R Earth symbol) are commonplace throughout the Galaxy, orbiting at least 16.5 per cent of Sun-like stars. Because these studies were sensitive to the sizes of the planets but not their masses, the question remains whether these Earth-sized planets are indeed similar to the Earth in bulk composition. The smallest planets for which masses have been accurately determined are Kepler-10b (1.42 R Earth symbol) and Kepler-36b (1.49 R Earth symbol), which are both significantly larger than the Earth. Recently, the planet Kepler-78b was discovered and found to have a radius of only 1.16 R Earth symbol. Here we report that the mass of this planet is 1.86 Earth masses. The resulting mean density of the planet is 5.57 g cm(-3), which is similar to that of the Earth and implies a composition of iron and rock.

  18. A Population of planetary systems characterized by short-period, Earth-sized planets

    Science.gov (United States)

    Steffen, Jason H.; Coughlin, Jeffrey L.

    2016-01-01

    We analyze data from the Quarter 1–17 Data Release 24 (Q1–Q17 DR24) planet candidate catalog from NASA’s Kepler mission, specifically comparing systems with single transiting planets to systems with multiple transiting planets, and identify a population of exoplanets with a necessarily distinct system architecture. Such an architecture likely indicates a different branch in their evolutionary past relative to the typical Kepler system. The key feature of these planetary systems is an isolated, Earth-sized planet with a roughly 1-d orbital period. We estimate that at least 24 of the 144 systems we examined (≳17%) are members of this population. Accounting for detection efficiency, such planetary systems occur with a frequency similar to the hot Jupiters. PMID:27790984

  19. Observing the Atmospheres of Known Temperate Earth-sized Planets with JWST

    Science.gov (United States)

    Morley, Caroline V.; Kreidberg, Laura; Rustamkulov, Zafar; Robinson, Tyler; Fortney, Jonathan J.

    2017-12-01

    Nine transiting Earth-sized planets have recently been discovered around nearby late-M dwarfs, including the TRAPPIST-1 planets and two planets discovered by the MEarth survey, GJ 1132b and LHS 1140b. These planets are the smallest known planets that may have atmospheres amenable to detection with the James Webb Space Telescope (JWST). We present model thermal emission and transmission spectra for each planet, varying composition and surface pressure of the atmosphere. We base elemental compositions on those of Earth, Titan, and Venus and calculate the molecular compositions assuming chemical equilibrium, which can strongly depend on temperature. Both thermal emission and transmission spectra are sensitive to the atmospheric composition; thermal emission spectra are sensitive to surface pressure and temperature. We predict the observability of each planet’s atmosphere with JWST. GJ 1132b and TRAPPIST-1b are excellent targets for emission spectroscopy with JWST/MIRI, requiring fewer than 10 eclipse observations. Emission photometry for TRAPPIST-1c requires 5-15 eclipses; LHS 1140b and TRAPPIST-1d, TRAPPIST-1e, and TRAPPIST-1f, which could possibly have surface liquid water, may be accessible with photometry. Seven of the nine planets are strong candidates for transmission spectroscopy measurements with JWST, although the number of transits required depends strongly on the planets’ actual masses. Using the measured masses, fewer than 20 transits are required for a 5σ detection of spectral features for GJ 1132b and six of the TRAPPIST-1 planets. Dedicated campaigns to measure the atmospheres of these nine planets will allow us, for the first time, to probe formation and evolution processes of terrestrial planetary atmospheres beyond our solar system.

  20. Zodiacal Exoplanets in Time (ZEIT). VI. A Three-planet System in the Hyades Cluster Including an Earth-sized Planet

    Science.gov (United States)

    Mann, Andrew W.; Vanderburg, Andrew; Rizzuto, Aaron C.; Kraus, Adam L.; Berlind, Perry; Bieryla, Allyson; Calkins, Michael L.; Esquerdo, Gilbert A.; Latham, David W.; Mace, Gregory N.; Morris, Nathan R.; Quinn, Samuel N.; Sokal, Kimberly R.; Stefanik, Robert P.

    2018-01-01

    Planets in young clusters are powerful probes of the evolution of planetary systems. Here we report the discovery of three planets transiting EPIC 247589423, a late-K dwarf in the Hyades (≃800 Myr) cluster, and robust detection limits for additional planets in the system. The planets were identified from their K2 light curves as part of our survey of young clusters and star-forming regions. The smallest planet has a radius comparable to Earth ({0.99}-0.04+0.06{R}\\oplus ), making it one of the few Earth-sized planets with a known, young age. The two larger planets are likely a mini-Neptune and a super-Earth, with radii of {2.91}-0.10+0.11{R}\\oplus and {1.45}-0.08+0.11{R}\\oplus , respectively. The predicted radial velocity signals from these planets are between 0.4 and 2 m s-1, achievable with modern precision RV spectrographs. Because the target star is bright (V = 11.2) and has relatively low-amplitude stellar variability for a young star (2-6 mmag), EPIC 247589423 hosts the best known planets in a young open cluster for precise radial velocity follow-up, enabling a robust test of earlier claims that young planets are less dense than their older counterparts.

  1. Discovery of Temperate Earth-Sized Planets Transiting a Nearby Ultracool Dwarf Star

    Science.gov (United States)

    Jehin, Emmanuel; Gillon, Michael; Lederer, Susan M.; Delrez, Laetitia; De Wit, Julien; Burdanov, Artem; Van Grootel, Valerie; Burgasser, Adam; Triaud, Amaury; Demory, Brice-Olivier; hide

    2016-01-01

    We report the discovery of three short-period Earth-sized planets transiting a nearby ultracool dwarf star using data collected by the Liège TRAPPIST telescope, located in la Silla (Chile). TRAPPIST-1 is an isolated M8.0+/-0.5-type dwarf star at a distance of 12.0+/-0.4 parsecs as measured by its trigonometric parallax, with an age constrained to be > 500 Myr, and with a luminosity, mass, and radius of 0.05%, 8% and 11.5% those of the Sun, respectively. The small size of the host star, only slightly larger than Jupiter, translates into Earth-like radii for the three discovered planets, as deduced from their transit depths. The inner two planets receive four and two times the irradiation of Earth, respectively, placing them close to the inner edge of the habitable zone of the star. Several orbits remain possible for the third planet based on our current data. The infrared brightness of the host star combined with its Jupiter-like size offer the possibility of thoroughly characterizing the components of this nearby planetary system.

  2. Thermal-orbital coupled tidal heating and habitability of Martian-sized extrasolar planets around M stars

    Energy Technology Data Exchange (ETDEWEB)

    Shoji, D.; Kurita, K. [Earthquake Research Institute, University of Tokyo, Tokyo (Japan)

    2014-07-01

    M-type stars are good targets in the search for habitable extrasolar planets. Due to their low effective temperatures, the habitable zone of M stars is very close to the stars themselves. For planets that are close to their stars, tidal heating plays an important role in thermal and orbital evolutions, especially when the planet's orbit has a relatively large eccentricity. Although tidal heating interacts with the thermal state and the orbit of the planet, such coupled calculations for extrasolar planets around M stars have not been conducted. We perform coupled calculations using simple structural and orbital models and analyze the thermal state and habitability of a terrestrial planet. Considering this planet to be Martian-sized, the tide heats up and partially melts the mantle, maintaining an equilibrium state if the mass of the star is less than 0.2 times the mass of the Sun and the initial eccentricity of the orbit is more than 0.2. The reduction of heat dissipation due to the melted mantle allows the planet to stay in the habitable zone for more than 10 Gyr even though the orbital distance is small. The surface heat flux at the equilibrium state is between that of Mars and Io. The thermal state of the planet mainly depends on the initial value of the eccentricity and the mass of the star.

  3. A SEARCH FOR LOST PLANETS IN THEKEPLERMULTI-PLANET SYSTEMS AND THE DISCOVERY OF A LONG PERIOD, NEPTUNE-SIZED EXOPLANET KEPLER-150 F.

    Science.gov (United States)

    Schmitt, Joseph R; Jenkins, Jon M; Fischer, Debra A

    2017-04-01

    The vast majority of the 4700 confirmed planets and planet candidates discovered by the Kepler space telescope were first found by the Kepler pipeline. In the pipeline, after a transit signal is found, all data points associated with those transits are removed, creating a "Swiss cheese"-like light curve full of holes, which is then used for subsequent transit searches. These holes could render an additional planet undetectable (or "lost"). We examine a sample of 114 stars with 3+ confirmed planets to see the effect that this "Swiss cheesing" may have. A simulation determined that the probability that a transiting planet is lost due to the transit masking is low, but non-neglible, reaching a plateau at ~3.3% lost in the period range of P = 400 - 500 days. We then model the transits in all quarters of each star and subtract out the transit signals, restoring the in-transit data points, and use the Kepler pipeline to search the transit-subtracted (i.e., transit-cleaned) light curves. However, the pipeline did not discover any credible new transit signals. This demonstrates the validity and robustness of the Kepler pipeline's choice to use transit masking over transit subtraction. However, a follow-up visual search through all the transit-subtracted data, which allows for easier visual identification of new transits, revealed the existence of a new, Neptune-sized exoplanet. Kepler-150 f ( P = 637.2 days, R P = 3.86 R ⊕ ) is confirmed using a combination of false positive probability analysis, transit duration analysis, and the planet multiplicity argument.

  4. Occurrence and core-envelope structure of 1–4× Earth-size planets around Sun-like stars

    Science.gov (United States)

    Marcy, Geoffrey W.; Weiss, Lauren M.; Petigura, Erik A.; Isaacson, Howard; Howard, Andrew W.; Buchhave, Lars A.

    2014-01-01

    Small planets, 1–4× the size of Earth, are extremely common around Sun-like stars, and surprisingly so, as they are missing in our solar system. Recent detections have yielded enough information about this class of exoplanets to begin characterizing their occurrence rates, orbits, masses, densities, and internal structures. The Kepler mission finds the smallest planets to be most common, as 26% of Sun-like stars have small, 1–2 R⊕ planets with orbital periods under 100 d, and 11% have 1–2 R⊕ planets that receive 1–4× the incident stellar flux that warms our Earth. These Earth-size planets are sprinkled uniformly with orbital distance (logarithmically) out to 0.4 the Earth–Sun distance, and probably beyond. Mass measurements for 33 transiting planets of 1–4 R⊕ show that the smallest of them, R stars that are rich in heavy elements, while rocky planets occur around stars having a range of heavy element abundances. Defining habitable zones remains difficult, without benefit of either detections of life elsewhere or an understanding of life’s biochemical origins. PMID:24912169

  5. Occurrence and core-envelope structure of 1-4× Earth-size planets around Sun-like stars.

    Science.gov (United States)

    Marcy, Geoffrey W; Weiss, Lauren M; Petigura, Erik A; Isaacson, Howard; Howard, Andrew W; Buchhave, Lars A

    2014-09-02

    Small planets, 1-4× the size of Earth, are extremely common around Sun-like stars, and surprisingly so, as they are missing in our solar system. Recent detections have yielded enough information about this class of exoplanets to begin characterizing their occurrence rates, orbits, masses, densities, and internal structures. The Kepler mission finds the smallest planets to be most common, as 26% of Sun-like stars have small, 1-2 R⊕ planets with orbital periods under 100 d, and 11% have 1-2 R⊕ planets that receive 1-4× the incident stellar flux that warms our Earth. These Earth-size planets are sprinkled uniformly with orbital distance (logarithmically) out to 0.4 the Earth-Sun distance, and probably beyond. Mass measurements for 33 transiting planets of 1-4 R⊕ show that the smallest of them, R stars that are rich in heavy elements, while rocky planets occur around stars having a range of heavy element abundances. Defining habitable zones remains difficult, without benefit of either detections of life elsewhere or an understanding of life's biochemical origins.

  6. Coupling SPH and thermochemical models of planets: Methodology and example of a Mars-sized body

    Science.gov (United States)

    Golabek, G. J.; Emsenhuber, A.; Jutzi, M.; Asphaug, E. I.; Gerya, T. V.

    2018-02-01

    Giant impacts have been suggested to explain various characteristics of terrestrial planets and their moons. However, so far in most models only the immediate effects of the collisions have been considered, while the long-term interior evolution of the impacted planets was not studied. Here we present a new approach, combining 3-D shock physics collision calculations with 3-D thermochemical interior evolution models. We apply the combined methods to a demonstration example of a giant impact on a Mars-sized body, using typical collisional parameters from previous studies. While the material parameters (equation of state, rheology model) used in the impact simulations can have some effect on the long-term evolution, we find that the impact angle is the most crucial parameter for the resulting spatial distribution of the newly formed crust. The results indicate that a dichotomous crustal pattern can form after a head-on collision, while this is not the case when considering a more likely grazing collision. Our results underline that end-to-end 3-D calculations of the entire process are required to study in the future the effects of large-scale impacts on the evolution of planetary interiors.

  7. The size, shape, density and ring of the dwarf planet Haumea from a stellar occultation

    Science.gov (United States)

    Ortiz, J. L.; Santos-Sanz, P.; Sicardy, B.; Benedetti-Rossi, G.; Bérard, D.; Morales, N.; Duffard, R.; Braga-Ribas, F.; Hopp, U.; Ries, C.; Nascimbeni, V.; Marzari, F.; Granata, V.; Pál, A.; Kiss, C.; Pribulla, T.; Komžík, R.; Hornoch, K.; Pravec, P.; Bacci, P.; Maestripieri, M.; Nerli, L.; Mazzei, L.; Bachini, M.; Martinelli, F.; Succi, G.; Ciabattari, F.; Mikuz, H.; Carbognani, A.; Gaehrken, B.; Mottola, S.; Hellmich, S.; Rommel, F. L.; Fernández-Valenzuela, E.; Bagatin, A. Campo; Cikota, S.; Cikota, A.; Lecacheux, J.; Vieira-Martins, R.; Camargo, J. I. B.; Assafin, M.; Colas, F.; Behrend, R.; Desmars, J.; Meza, E.; Alvarez-Candal, A.; Beisker, W.; Gomes-Junior, A. R.; Morgado, B. E.; Roques, F.; Vachier, F.; Berthier, J.; Mueller, T. G.; Madiedo, J. M.; Unsalan, O.; Sonbas, E.; Karaman, N.; Erece, O.; Koseoglu, D. T.; Ozisik, T.; Kalkan, S.; Guney, Y.; Niaei, M. S.; Satir, O.; Yesilyaprak, C.; Puskullu, C.; Kabas, A.; Demircan, O.; Alikakos, J.; Charmandaris, V.; Leto, G.; Ohlert, J.; Christille, J. M.; Szakáts, R.; Farkas, A. Takácsné; Varga-Verebélyi, E.; Marton, G.; Marciniak, A.; Bartczak, P.; Santana-Ros, T.; Butkiewicz-Bąk, M.; Dudziński, G.; Alí-Lagoa, V.; Gazeas, K.; Tzouganatos, L.; Paschalis, N.; Tsamis, V.; Sánchez-Lavega, A.; Pérez-Hoyos, S.; Hueso, R.; Guirado, J. C.; Peris, V.; Iglesias-Marzoa, R.

    2017-10-01

    Haumea—one of the four known trans-Neptunian dwarf planets—is a very elongated and rapidly rotating body. In contrast to other dwarf planets, its size, shape, albedo and density are not well constrained. The Centaur Chariklo was the first body other than a giant planet known to have a ring system, and the Centaur Chiron was later found to possess something similar to Chariklo’s rings. Here we report observations from multiple Earth-based observatories of Haumea passing in front of a distant star (a multi-chord stellar occultation). Secondary events observed around the main body of Haumea are consistent with the presence of a ring with an opacity of 0.5, width of 70 kilometres and radius of about 2,287 kilometres. The ring is coplanar with both Haumea’s equator and the orbit of its satellite Hi’iaka. The radius of the ring places it close to the 3:1 mean-motion resonance with Haumea’s spin period—that is, Haumea rotates three times on its axis in the time that a ring particle completes one revolution. The occultation by the main body provides an instantaneous elliptical projected shape with axes of about 1,704 kilometres and 1,138 kilometres. Combined with rotational light curves, the occultation constrains the three-dimensional orientation of Haumea and its triaxial shape, which is inconsistent with a homogeneous body in hydrostatic equilibrium. Haumea’s largest axis is at least 2,322 kilometres, larger than previously thought, implying an upper limit for its density of 1,885 kilograms per cubic metre and a geometric albedo of 0.51, both smaller than previous estimates. In addition, this estimate of the density of Haumea is closer to that of Pluto than are previous estimates, in line with expectations. No global nitrogen- or methane-dominated atmosphere was detected.

  8. Kepler-413B: A slightly misaligned, Neptune-size transiting circumbinary planet

    Energy Technology Data Exchange (ETDEWEB)

    Kostov, V. B.; McCullough, P. R.; Tsvetanov, Z. I. [Department of Physics and Astronomy, Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218 (United States); Carter, J. A. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Deleuil, M.; Díaz, R. F. [Laboratoire d' Astrophysique de Marseille, 38 rue Frédéric Joliot-Curie, F-13388 Marseille cedex 13 (France); Fabrycky, D. C. [Department of Astronomy and Astrophysics, University of Chicago, 5640 South Ellis Avenue, Chicago, IL 60637 (United States); Hébrard, G. [Institut d' Astrophysique de Paris, UMR 7095 CNRS, Université Pierre and Marie Curie, 98 bis boulevard Arago, F-75014 Paris (France); Hinse, T. C. [Korea Astronomy and Space Science Institute (KASI), Advanced Astronomy and Space Science Division, Daejeon 305-348 (Korea, Republic of); Mazeh, T. [Department of Astronomy and Astrophysics, Tel Aviv University, 69978 Tel Aviv (Israel); Orosz, J. A.; Welsh, W. F., E-mail: vkostov@pha.jhu.edu [Department of Astronomy, San Diego State University, 5500 Campanile Drive, San Diego, CA 92182 (United States)

    2014-03-20

    We report the discovery of a transiting, R{sub p} = 4.347 ± 0.099R {sub ⊕}, circumbinary planet (CBP) orbiting the Kepler K+M eclipsing binary (EB) system KIC 12351927 (Kepler-413) every ∼66 days on an eccentric orbit with a{sub p} = 0.355 ± 0.002 AU, e{sub p} = 0.118 ± 0.002. The two stars, with M{sub A} = 0.820 ± 0.015 M {sub ☉}, R{sub A} = 0.776 ± 0.009 R {sub ☉} and M{sub B} = 0.542 ± 0.008 M {sub ☉}, R{sub B} = 0.484 ± 0.024 R {sub ☉}, respectively, revolve around each other every 10.11615 ± 0.00001 days on a nearly circular (e {sub EB} = 0.037 ± 0.002) orbit. The orbital plane of the EB is slightly inclined to the line of sight (i {sub EB} = 87.°33 ± 0.°06), while that of the planet is inclined by ∼2.°5 to the binary plane at the reference epoch. Orbital precession with a period of ∼11 yr causes the inclination of the latter to the sky plane to continuously change. As a result, the planet often fails to transit the primary star at inferior conjunction, causing stretches of hundreds of days with no transits (corresponding to multiple planetary orbital periods). We predict that the next transit will not occur until 2020. The orbital configuration of the system places the planet slightly closer to its host stars than the inner edge of the extended habitable zone. Additionally, the orbital configuration of the system is such that the CBP may experience Cassini State dynamics under the influence of the EB, in which the planet's obliquity precesses with a rate comparable to its orbital precession. Depending on the angular precession frequency of the CBP, it could potentially undergo obliquity fluctuations of dozens of degrees (and complex seasonal cycles) on precession timescales.

  9. The Orbital and Planetary Phase Variations of Jupiter-sized Planets: Characterizing Present and Future Giants

    Science.gov (United States)

    Mayorga, Laura C.; Jackiewicz, Jason; Rages, Kathy; West, Robert; Knowles, Ben; Lewis, Nikole K.; Marley, Mark S.

    2018-01-01

    Knowledge of how the brightness and color of a planet varies with viewing angle is essential for the design of future direct imaging missions and deriving constraints on atmospheric properties. However, measuring the phase curves for the solar system gas giants is impossible from the ground. Using data Cassini/ISS obtained during its flyby of Jupiter, I measured Jupiter's phase curve in six bands spanning 400-1000 nm. I found that Jupiter's brightness is less than that of a Lambertian scatterer and that its color varies more with phase angle than predicted by theoretical models. For hot Jupiters, the light from the planet cannot be spatially isolated from that of the star. As a result, determining the planetary phase curve requires removing the phase-dependent contributions from the host star. I consider the effect of varying the stellar model and present a parameterization of the Doppler beaming amplitude that depends upon the planetary mass, orbital period, and the stellar temperature. I consider the detectability of Doppler beaming amplitudes with data from TESS and find that TESS will be less sensitive to this signal than Kepler. This work was supported by the National Science Foundation Graduate Research Fellowship Program and the New Mexico Higher Education Department Graduate Scholarship Program.

  10. A Spitzer five-band analysis of the Jupiter-sized planet TrES-1

    Energy Technology Data Exchange (ETDEWEB)

    Cubillos, Patricio; Harrington, Joseph; Foster, Andrew S. D.; Lust, Nate B.; Hardy, Ryan A.; Bowman, M. Oliver [Planetary Sciences Group, Department of Physics, University of Central Florida, Orlando, FL 32816-2385 (United States); Madhusudhan, Nikku, E-mail: pcubillos@fulbrightmail.org [Department of Physics and Department of Astronomy, Yale University, New Haven, CT 06511 (United States)

    2014-12-10

    With an equilibrium temperature of 1200 K, TrES-1 is one of the coolest hot Jupiters observed by Spitzer. It was also the first planet discovered by any transit survey and one of the first exoplanets from which thermal emission was directly observed. We analyzed all Spitzer eclipse and transit data for TrES-1 and obtained its eclipse depths and brightness temperatures in the 3.6 μm (0.083% ± 0.024%, 1270 ± 110 K), 4.5 μm (0.094% ± 0.024%, 1126 ± 90 K), 5.8 μm (0.162% ± 0.042%, 1205 ± 130 K), 8.0 μm (0.213% ± 0.042%, 1190 ± 130 K), and 16 μm (0.33% ± 0.12%, 1270 ± 310 K) bands. The eclipse depths can be explained, within 1σ errors, by a standard atmospheric model with solar abundance composition in chemical equilibrium, with or without a thermal inversion. The combined analysis of the transit, eclipse, and radial-velocity ephemerides gives an eccentricity of e=0.033{sub −0.031}{sup +0.015}, consistent with a circular orbit. Since TrES-1's eclipses have low signal-to-noise ratios, we implemented optimal photometry and differential-evolution Markov Chain Monte Carlo (MCMC) algorithms in our Photometry for Orbits, Eclipses, and Transits pipeline. Benefits include higher photometric precision and ∼10 times faster MCMC convergence, with better exploration of the phase space and no manual parameter tuning.

  11. Size distribution of particles in planetary rings. [applied to Saturn and terrestrial planets

    Science.gov (United States)

    Greenberg, R.; Davis, D. R.; Hartmann, W. K.; Chapman, C. R.

    1977-01-01

    Harris (1975) has suggested that the maximum size of particles in a planetary ring is controlled by collisional fragmentation rather than tidal stress. While this conclusion is probably true, estimated radius limits must be revised upward from Harris' values of a few kilometers by at least an order of magnitude. Accretion of particles within the Roche limit is also possible. These considerations affect theories concerning the evolution of Saturn's rings, of the moon, and of possible former satellites of Mercury and Venus. In the case of Saturn's rings, comparison of various theoretical scenarios with available observational evidence suggests that the rings formed from the breakup of larger particles rather than from original condensation as small particles. This process implies a distribution of particle sizes in Saturn's rings possibly ranging up to about 100 km but with most of the cross section in centimeter-scale particles.

  12. TRAPPIST-UCDTS: A prototype search for habitable planets transiting ultra-cool stars

    Directory of Open Access Journals (Sweden)

    Magain P.

    2013-04-01

    Full Text Available The ∼1000 nearest ultra-cool stars (spectral type M6 and latter represent a unique opportunity for the search for life outside solar system. Due to their small luminosity, their habitable zone is 30–100 times closer than for the Sun, the corresponding orbital periods ranging from one to a few days. Thanks to this proximity, the transits of a habitable planet are much more probable and frequent than for an Earth-Sun analog, while their tiny size (∼1 Jupiter radius leads to transits deep enough for a ground-based detection, even for sub-Earth size planets. Furthermore, a habitable planet transiting one of these nearby ultra-cool star would be amenable for a thorough atmospheric characterization, including the detection of possible biosignatures, notably with the near-to-come JWST. Motivated by these reasons, we have set up the concept of a ground-based survey optimized for detecting planets of Earth-size and below transiting the nearest Southern ultra-cool stars. To assess thoroughly the actual potential of this future survey, we are currently conducting a prototype mini-survey using the TRAPPIST robotic 60cm telescope located at La Silla ESO Observatory (Chile. We summarize here the preliminary results of this mini-survey that fully validate our concept.

  13. A Neptune-sized transiting planet closely orbiting a 5–10-million-year-old star.

    Science.gov (United States)

    David, Trevor J; Hillenbrand, Lynne A; Petigura, Erik A; Carpenter, John M; Crossfield, Ian J M; Hinkley, Sasha; Ciardi, David R; Howard, Andrew W; Isaacson, Howard T; Cody, Ann Marie; Schlieder, Joshua E; Beichman, Charles A; Barenfeld, Scott A

    2016-06-30

    Theories of the formation and early evolution of planetary systems postulate that planets are born in circumstellar disks, and undergo radial migration during and after dissipation of the dust and gas disk from which they formed. The precise ages of meteorites indicate that planetesimals—the building blocks of planets—are produced within the first million years of a star’s life. Fully formed planets are frequently detected on short orbital periods around mature stars. Some theories suggest that the in situ formation of planets close to their host stars is unlikely and that the existence of such planets is therefore evidence of large-scale migration. Other theories posit that planet assembly at small orbital separations may be common. Here we report a newly born, transiting planet orbiting its star with a period of 5.4 days. The planet is 50 per cent larger than Neptune, and its mass is less than 3.6 times that of Jupiter (at 99.7 per cent confidence), with a true mass likely to be similar to that of Neptune. The star is 5–10 million years old and has a tenuous dust disk extending outward from about twice the Earth–Sun separation, in addition to the fully formed planet located at less than one-twentieth of the Earth–Sun separation.

  14. Modeling Kepler Transit Light Curves as False Positives: Rejection of Blend Scenarios for Kepler-9, and Validation of Kepler-9 d, a Super-Earth-Size Planet in a Multiple System

    Science.gov (United States)

    2011-01-20

    in the field the rate of false positives relative to the rate of true planets (false alarm rate, FAR) can be written quite generally as FAR = NFP /( NFP ...Np), where NFP is the number of false positives and Np is the number of planets in the sample. Thus, the larger the number of planets we expect, the...product of BF and the size of the sample or NFP = BF × 156,097 = 0.016. The number of small planets expected in the sample is of course not known, and

  15. Terrestrial planet formation.

    Science.gov (United States)

    Righter, K; O'Brien, D P

    2011-11-29

    Advances in our understanding of terrestrial planet formation have come from a multidisciplinary approach. Studies of the ages and compositions of primitive meteorites with compositions similar to the Sun have helped to constrain the nature of the building blocks of planets. This information helps to guide numerical models for the three stages of planet formation from dust to planetesimals (~10(6) y), followed by planetesimals to embryos (lunar to Mars-sized objects; few 10(6) y), and finally embryos to planets (10(7)-10(8) y). Defining the role of turbulence in the early nebula is a key to understanding the growth of solids larger than meter size. The initiation of runaway growth of embryos from planetesimals ultimately leads to the growth of large terrestrial planets via large impacts. Dynamical models can produce inner Solar System configurations that closely resemble our Solar System, especially when the orbital effects of large planets (Jupiter and Saturn) and damping mechanisms, such as gas drag, are included. Experimental studies of terrestrial planet interiors provide additional constraints on the conditions of differentiation and, therefore, origin. A more complete understanding of terrestrial planet formation might be possible via a combination of chemical and physical modeling, as well as obtaining samples and new geophysical data from other planets (Venus, Mars, or Mercury) and asteroids.

  16. Observed properties of extrasolar planets.

    Science.gov (United States)

    Howard, Andrew W

    2013-05-03

    Observational surveys for extrasolar planets probe the diverse outcomes of planet formation and evolution. These surveys measure the frequency of planets with different masses, sizes, orbital characteristics, and host star properties. Small planets between the sizes of Earth and Neptune substantially outnumber Jupiter-sized planets. The survey measurements support the core accretion model, in which planets form by the accumulation of solids and then gas in protoplanetary disks. The diversity of exoplanetary characteristics demonstrates that most of the gross features of the solar system are one outcome in a continuum of possibilities. The most common class of planetary system detectable today consists of one or more planets approximately one to three times Earth's size orbiting within a fraction of the Earth-Sun distance.

  17. Kepler's first rocky planet

    DEFF Research Database (Denmark)

    Batalha, N.M.; Borucki, W.J.; Bryson, S.T.

    2011-01-01

    NASA's Kepler Mission uses transit photometry to determine the frequency of Earth-size planets in or near the habitable zone of Sun-like stars. The mission reached a milestone toward meeting that goal: the discovery of its first rocky planet, Kepler-10b. Two distinct sets of transit events were...... tests on the photometric and pixel flux time series established the viability of the planet candidates triggering ground-based follow-up observations. Forty precision Doppler measurements were used to confirm that the short-period transit event is due to a planetary companion. The parent star is bright...

  18. Magic Planet

    DEFF Research Database (Denmark)

    Jacobsen, Aase Roland

    2009-01-01

    Med den digitale globe som omdrejningspunkt bestemmer publikum, hvilken planet, der er i fokus. Vores solsystem udforskes interaktivt. Udgivelsesdato: november......Med den digitale globe som omdrejningspunkt bestemmer publikum, hvilken planet, der er i fokus. Vores solsystem udforskes interaktivt. Udgivelsesdato: november...

  19. Giant Planet Formation and Migration

    Science.gov (United States)

    Paardekooper, Sijme-Jan; Johansen, Anders

    2018-02-01

    Planets form in circumstellar discs around young stars. Starting with sub-micron sized dust particles, giant planet formation is all about growing 14 orders of magnitude in size. It has become increasingly clear over the past decades that during all stages of giant planet formation, the building blocks are extremely mobile and can change their semimajor axis by substantial amounts. In this chapter, we aim to give a basic overview of the physical processes thought to govern giant planet formation and migration, and to highlight possible links to water delivery.

  20. SPITZER OBSERVATIONS OF GJ 3470 b: A VERY LOW-DENSITY NEPTUNE-SIZE PLANET ORBITING A METAL-RICH M DWARF

    Energy Technology Data Exchange (ETDEWEB)

    Demory, Brice-Olivier; Seager, Sara [Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, 77 Massachusetts Ave., Cambridge, MA 02139 (United States); Torres, Guillermo [Harvard-Smithsonian Center for Astrophysics, 60 Garden St., Cambridge, MA 02138 (United States); Neves, Vasco; Santos, Nuno [Centro de Astrofisica, Universidade do Porto, Rua das Estrelas, 4150-762 Porto (Portugal); Rogers, Leslie [Department of Astrophysics, California Institute of Technology, MC 249-17, Pasadena, CA 91125 (United States); Gillon, Michaeel [Institut d' Astrophysique et de Geophysique, Universite de Liege, Allee du 6 Aout, 17, Bat. B5C, Liege 1 (Belgium); Horch, Elliott [Department of Physics, 501 Crescent Street, Southern Connecticut State University, New Haven, CT 06515 (United States); Sullivan, Peter [Department of Physics and Kavli Institute for Astrophysics and Space Research, MIT, 77 Massachusetts Avenue, Cambridge, MA 02138 (United States); Bonfils, Xavier; Delfosse, Xavier; Forveille, Thierry [UJF-Grenoble 1/CNRS-INSU, Institut de Planetologie et d' Astrophysique de Grenoble (IPAG) UMR 5274, Grenoble, F-38041 (France); Lovis, Christophe; Mayor, Michel; Udry, Stephane [Observatoire de Geneve, Universite de Geneve, 51 ch. des Maillettes, CH-1290 Versoix (Switzerland); Smalley, Barry, E-mail: demory@mit.edu [Astrophysics Group, Keele University, Staffordshire, ST55BG (United Kingdom)

    2013-05-10

    We present Spitzer/IRAC 4.5 {mu}m transit photometry of GJ 3470 b, a Neptune-size planet orbiting an M1.5 dwarf star with a 3.3 day period recently discovered in the course of the HARPS M-dwarf survey. We refine the stellar parameters by employing purely empirical mass-luminosity and surface brightness relations constrained by our updated value for the mean stellar density, and additional information from new near-infrared spectroscopic observations. We derive a stellar mass of M{sub *}= 0.539{sup +0.047}{sub -0.043} M{sub sun} and a radius of R{sub *}= 0.568{sup +0.037}{sub -0.031} R{sub sun}. We determine the host star of GJ 3470 b to be metal-rich, with a metallicity of [Fe/H] = +0.20 {+-} 0.10 and an effective temperature of T{sub eff} = 3600 {+-} 100 K. The revised stellar parameters yield a planetary radius R{sub p}= 4.83{sub -0.21}{sup +0.22} R{sub Circled-Plus} that is 13% larger than the value previously reported in the literature. We find a planetary mass M{sub p}= 13.9{sup +1.5}{sub -1.4} M{sub Circled-Plus} that translates to a very low planetary density, {rho}{sub p}= 0.72{sup +0.13}{sub -0.12} g cm{sup -3}, which is 33% smaller than the original value. With a mean density half of that of GJ 436 b, GJ 3470 b is an example of a very low-density low-mass planet, similar to Kepler-11 d, Kepler-11 e, and Kepler-18 c, but orbiting a much brighter nearby star that is more conducive to follow-up studies.

  1. Kepler planet-detection mission

    DEFF Research Database (Denmark)

    Borucki...[], William J.; Koch, David; Buchhave, Lars C. Astrup

    2010-01-01

    The Kepler mission was designed to determine the frequency of Earth-sized planets in and near the habitable zone of Sun-like stars. The habitable zone is the region where planetary temperatures are suitable for water to exist on a planet’s surface. During the first 6 weeks of observations, Kepler...... is one of the lowest-density planets (~0.17 gram per cubic centimeter) yet detected. Kepler-5b, -6b, and -8b confirm the existence of planets with densities lower than those predicted for gas giant planets....

  2. Taxonomy of the extrasolar planet.

    Science.gov (United States)

    Plávalová, Eva

    2012-04-01

    When a star is described as a spectral class G2V, we know that the star is similar to our Sun. We know its approximate mass, temperature, age, and size. When working with an extrasolar planet database, it is very useful to have a taxonomy scale (classification) such as, for example, the Harvard classification for stars. The taxonomy has to be easily interpreted and present the most relevant information about extrasolar planets. I propose an extrasolar planet taxonomy scale with four parameters. The first parameter concerns the mass of an extrasolar planet in the form of units of the mass of other known planets, where M represents the mass of Mercury, E that of Earth, N Neptune, and J Jupiter. The second parameter is the planet's distance from its parent star (semimajor axis) described in a logarithm with base 10. The third parameter is the mean Dyson temperature of the extrasolar planet, for which I established four main temperature classes: F represents the Freezing class, W the Water class, G the Gaseous class, and R the Roasters class. I devised one additional class, however: P, the Pulsar class, which concerns extrasolar planets orbiting pulsar stars. The fourth parameter is eccentricity. If the attributes of the surface of the extrasolar planet are known, we are able to establish this additional parameter where t represents a terrestrial planet, g a gaseous planet, and i an ice planet. According to this taxonomy scale, for example, Earth is 1E0W0t, Neptune is 1N1.5F0i, and extrasolar planet 55 Cnc e is 9E-1.8R1.

  3. Pluto: Planet or "Dwarf Planet"?

    Science.gov (United States)

    Voelzke, M. R.; de Araújo, M. S. T.

    2010-09-01

    In August 2006 during the XXVI General Assembly of the International Astronomical Union (IAU), taken place in Prague, Czech Republic, new parameters to define a planet were established. According to this new definition Pluto will be no more the ninth planet of the Solar System but it will be changed to be a "dwarf planet". This reclassification of Pluto by the academic community clearly illustrates how dynamic science is and how knowledge of different areas can be changed and evolves through the time, allowing to perceive Science as a human construction in a constant transformation, subject to political, social and historical contexts. These epistemological characteristics of Science and, in this case, of Astronomy, constitute important elements to be discussed in the lessons, so that this work contributes to enable Science and Physics teachers who perform a basic education to be always up to date on this important astronomical fact and, thereby, carry useful information to their teaching.

  4. A New Family of Planets ? "Ocean Planets"

    OpenAIRE

    Leger, A.; Selsis, F.; Sotin, C.; Guillot, T.; Despois, D.; Lammer, H.; Ollivier, M.; Brachet, F.; Labeque, A.; Valette, C.

    2003-01-01

    A new family of planets is considered which is between rochy terrestrial planets and gaseous giant ones: "Ocean-Planets". We present the possible formation, composition and internal models of these putative planets, including that of their ocean, as well as their possible Exobiology interest. These planets should be detectable by planet detection missions such as Eddington and Kepler, and possibly COROT (lauch scheduled in 2006). They would be ideal targets for spectroscopic missions such as ...

  5. Habitable zone limits for dry planets.

    Science.gov (United States)

    Abe, Yutaka; Abe-Ouchi, Ayako; Sleep, Norman H; Zahnle, Kevin J

    2011-06-01

    Most discussion of habitable planets has focused on Earth-like planets with globally abundant liquid water. For an "aqua planet" like Earth, the surface freezes if far from its sun, and the water vapor greenhouse effect runs away if too close. Here we show that "land planets" (desert worlds with limited surface water) have wider habitable zones than aqua planets. For planets at the inner edge of the habitable zone, a land planet has two advantages over an aqua planet: (i) the tropics can emit longwave radiation at rates above the traditional runaway limit because the air is unsaturated and (ii) the dry air creates a dry stratosphere that limits hydrogen escape. At the outer limits of the habitable zone, the land planet better resists global freezing because there is less water for clouds, snow, and ice. Here we describe a series of numerical experiments using a simple three-dimensional global climate model for Earth-sized planets. Other things (CO(2), rotation rate, surface pressure) unchanged, we found that liquid water remains stable at the poles of a low-obliquity land planet until net insolation exceeds 415 W/m(2) (170% that of modern Earth), compared to 330 W/m(2) (135%) for the aqua planet. At the outer limits, we found that a low-obliquity land planet freezes at 77%, while the aqua planet freezes at 90%. High-obliquity land and aqua planets freeze at 58% and 72%, respectively, with the poles offering the last refuge. We show that it is possible that, as the Sun brightens, an aqua planet like Earth can lose most of its hydrogen and become a land planet without first passing through a sterilizing runaway greenhouse. It is possible that Venus was a habitable land planet as recently as 1 billion years ago.

  6. The Planet Formation Imager

    Science.gov (United States)

    Kraus, S.; Buscher, D. F.; Monnier, J. D.; PFI Science, the; Technical Working Group

    2014-04-01

    Among the most fascinating and hotly-debated areas in contemporary astrophysics are the means by which planetary systems are assembled from the large rotating disks of gas and dust which attend a stellar birth. Although important work is being done both in theory and observation, a full understanding of the physics of planet formation can only be achieved by opening observational windows able to directly witness the process in action. The key requirement is then to probe planet-forming systems at the natural spatial scales over which material is being assembled. By definition, this is the so-called Hill Sphere which delineates the region of influence of a gravitating body within its surrounding environment. The Planet Formation Imager project has crystallized around this challenging goal: to deliver resolved images of Hill-Sphere-sized structures within candidate planet-hosting disks in the nearest star-forming regions. In this contribution we outline the primary science case of PFI and discuss how PFI could significantly advance our understanding of the architecture and potential habitability of planetary systems. We present radiation-hydrodynamics simulations from which we derive preliminary specifications that guide the design of the facility. Finally, we give an overview about the interferometric and non-interferometric technologies that we are investigating in order to meet the specifications.

  7. Planet Ocean

    Science.gov (United States)

    Afonso, Isabel

    2014-05-01

    A more adequate name for Planet Earth could be Planet Ocean, seeing that ocean water covers more than seventy percent of the planet's surface and plays a fundamental role in the survival of almost all living species. Actually, oceans are aqueous solutions of extraordinary importance due to its direct implications in the current living conditions of our planet and its potential role on the continuity of life as well, as long as we know how to respect the limits of its immense but finite capacities. We may therefore state that natural aqueous solutions are excellent contexts for the approach and further understanding of many important chemical concepts, whether they be of chemical equilibrium, acid-base reactions, solubility and oxidation-reduction reactions. The topic of the 2014 edition of GIFT ('Our Changing Planet') will explore some of the recent complex changes of our environment, subjects that have been lately included in Chemistry teaching programs. This is particularly relevant on high school programs, with themes such as 'Earth Atmosphere: radiation, matter and structure', 'From Atmosphere to the Ocean: solutions on Earth and to Earth', 'Spring Waters and Public Water Supply: Water acidity and alkalinity'. These are the subjects that I want to develop on my school project with my pupils. Geographically, our school is located near the sea in a region where a stream flows into the sea. Besides that, our school water comes from a borehole which shows that the quality of the water we use is of significant importance. This project will establish and implement several procedures that, supported by physical and chemical analysis, will monitor the quality of water - not only the water used in our school, but also the surrounding waters (stream and beach water). The samples will be collected in the borehole of the school, in the stream near the school and in the beach of Carcavelos. Several physical-chemical characteristics related to the quality of the water will

  8. Our Solar System Features Eight Planets

    Science.gov (United States)

    2009-01-01

    Our solar system features eight planets, seen in this artist's diagram. Although there is some debate within the science community as to whether Pluto should be classified as a Planet or a dwarf planet, the International Astronomical Union has decided on the term plutoid as a name for dwarf planets like Pluto. This representation is intentionally fanciful, as the planets are depicted far closer together than they really are. Similarly, the bodies' relative sizes are inaccurate. This is done for the purpose of being able to depict the solar system and still represent the bodies with some detail. (Otherwise the Sun would be a mere speck, and the planets even the majestic Jupiter would be far too small to be seen.)

  9. Astronomy: Ring detected around a dwarf planet

    Science.gov (United States)

    Sickafoose, Amanda A.

    2017-10-01

    Observations of the distant dwarf planet Haumea constrain its size, shape and density, and reveal an encircling planetary ring. The discovery suggests that rings are not as rare in the Solar System as previously thought. See Letter p.219

  10. Habitable planets with high obliquities.

    Science.gov (United States)

    Williams, D M; Kasting, J F

    1997-01-01

    Earth's obliquity would vary chaotically from 0 degrees to 85 degrees were it not for the presence of the Moon (J. Laskar, F. Joutel, and P. Robutel, 1993, Nature 361, 615-617). The Moon itself is thought to be an accident of accretion, formed by a glancing blow from a Mars-sized planetesimal. Hence, planets with similar moons and stable obliquities may be extremely rare. This has lead Laskar and colleagues to suggest that the number of Earth-like planets with high obliquities and temperate, life-supporting climates may be small. To test this proposition, we have used an energy-balance climate model to simulate Earth's climate at obliquities up to 90 degrees. We show that Earth's climate would become regionally severe in such circumstances, with large seasonal cycles and accompanying temperature extremes on middle- and high-latitude continents which might be damaging to many forms of life. The response of other, hypothetical, Earth-like planets to large obliquity fluctuations depends on their land-sea distribution and on their position within the habitable zone (HZ) around their star. Planets with several modest-sized continents or equatorial supercontinents are more climatically stable than those with polar supercontinents. Planets farther out in the HZ are less affected by high obliquities because their atmospheres should accumulate CO2 in response to the carbonate-silicate cycle. Dense, CO2-rich atmospheres transport heat very effectively and therefore limit the magnitude of both seasonal cycles and latitudinal temperature gradients. We conclude that a significant fraction of extrasolar Earth-like planets may still be habitable, even if they are subject to large obliquity fluctuations.

  11. Masses, Radii, and Orbits of Small Kepler Planets: The Transition from Gaseous to Rocky Planets

    NARCIS (Netherlands)

    Marcy, G.W.; et al., [Unknown; Hekker, S.

    2014-01-01

    We report on the masses, sizes, and orbits of the planets orbiting 22 Kepler stars. There are 49 planet candidates around these stars, including 42 detected through transits and 7 revealed by precise Doppler measurements of the host stars. Based on an analysis of the Kepler brightness measurements,

  12. White dwarf planets

    Directory of Open Access Journals (Sweden)

    Bonsor Amy

    2013-04-01

    Full Text Available The recognition that planets may survive the late stages of stellar evolution, and the prospects for finding them around White Dwarfs, are growing. We discuss two aspects governing planetary survival through stellar evolution to the White Dwarf stage. First we discuss the case of a single planet, and its survival under the effects of stellar mass loss, radius expansion, and tidal orbital decay as the star evolves along the Asymptotic Giant Branch. We show that, for stars initially of 1 − 5 M⊙, any planets within about 1 − 5 AU will be engulfed, this distance depending on the stellar and planet masses and the planet's eccentricity. Planets engulfed by the star's envelope are unlikely to survive. Hence, planets surviving the Asymptotic Giant Branch phase will probably be found beyond ∼ 2 AU for a 1  M⊙ progenitor and ∼ 10 AU for a 5 M⊙ progenitor. We then discuss the evolution of two-planet systems around evolving stars. As stars lose mass, planet–planet interactions become stronger, and many systems stable on the Main Sequence become destabilised following evolution of the primary. The outcome of such instabilities is typically the ejection of one planet, with the survivor being left on an eccentric orbit. These eccentric planets could in turn be responsible for feeding planetesimals into the neighbourhood of White Dwarfs, causing observed pollution and circumstellar discs.

  13. Direct Imaging of Warm Extrasolar Planets

    Energy Technology Data Exchange (ETDEWEB)

    Macintosh, B

    2005-04-11

    One of the most exciting scientific discoveries in the last decade of the twentieth century was the first detection of planets orbiting a star other than our own. By now more than 130 extrasolar planets have been discovered indirectly, by observing the gravitational effects of the planet on the radial velocity of its parent star. This technique has fundamental limitations: it is most sensitive to planets close to their star, and it determines only a planet's orbital period and a lower limit on the planet's mass. As a result, all the planetary systems found so far are very different from our own--they have giant Jupiter-sized planets orbiting close to their star, where the terrestrial planets are found in our solar system. Such systems have overturned the conventional paradigm of planet formation, but have no room in them for habitable Earth-like planets. A powerful complement to radial velocity detections of extrasolar planets will be direct imaging--seeing photons from the planet itself. Such a detection would allow photometric measurements to determine the temperature and radius of a planet. Also, direct detection is most sensitive to planets in wide orbits, and hence more capable of seeing solar systems resembling our own, since a giant planet in a wide orbit does not preclude the presence of an Earth-like planet closer to the star. Direct detection, however, is extremely challenging. Jupiter is roughly a billion times fainter than our sun. Two techniques allowed us to overcome this formidable contrast and attempt to see giant planets directly. The first is adaptive optics (AO) which allows giant earth-based telescopes, such as the 10 meter W.M. Keck telescope, to partially overcome the blurring effects of atmospheric turbulence. The second is looking for young planets: by searching in the infrared for companions to young stars, we can see thermal emission from planets that are still warm with the heat of their formation. Together with a UCLA team that

  14. From Pixels to Planets

    Science.gov (United States)

    Brownston, Lee; Jenkins, Jon M.

    2015-01-01

    The Kepler Mission was launched in 2009 as NASAs first mission capable of finding Earth-size planets in the habitable zone of Sun-like stars. Its telescope consists of a 1.5-m primary mirror and a 0.95-m aperture. The 42 charge-coupled devices in its focal plane are read out every half hour, compressed, and then downlinked monthly. After four years, the second of four reaction wheels failed, ending the original mission. Back on earth, the Science Operations Center developed the Science Pipeline to analyze about 200,000 target stars in Keplers field of view, looking for evidence of periodic dimming suggesting that one or more planets had crossed the face of its host star. The Pipeline comprises several steps, from pixel-level calibration, through noise and artifact removal, to detection of transit-like signals and the construction of a suite of diagnostic tests to guard against false positives. The Kepler Science Pipeline consists of a pipeline infrastructure written in the Java programming language, which marshals data input to and output from MATLAB applications that are executed as external processes. The pipeline modules, which underwent continuous development and refinement even after data started arriving, employ several analytic techniques, many developed for the Kepler Project. Because of the large number of targets, the large amount of data per target and the complexity of the pipeline algorithms, the processing demands are daunting. Some pipeline modules require days to weeks to process all of their targets, even when run on NASA's 128-node Pleiades supercomputer. The software developers are still seeking ways to increase the throughput. To date, the Kepler project has discovered more than 4000 planetary candidates, of which more than 1000 have been independently confirmed or validated to be exoplanets. Funding for this mission is provided by NASAs Science Mission Directorate.

  15. Kepler-16: A Transiting Circumbinary Planet

    OpenAIRE

    Doyle, Laurance R.; Carter, Joshua A.; Fabrycky, Daniel C.; Slawson, Robert W.; Howell, Steve B.; Winn, Joshua N.; Orosz, Jerome A.; Prsa, Andrej; Welsh, William F.; Quinn, Samuel N.; Latham, David; Torres, Guillermo; Buchhave, Lars A.; Marcy, Geoffrey W.; Fortney, Jonathan J.

    2011-01-01

    We report the detection of a planet whose orbit surrounds a pair of low-mass stars. Data from the Kepler spacecraft reveal transits of the planet across both stars, in addition to the mutual eclipses of the stars, giving precise constraints on the absolute dimensions of all three bodies. The planet is comparable to Saturn in mass and size, and is on a nearly circular 229-day orbit around its two parent stars. The eclipsing stars are 20% and 69% as massive as the sun, and have an eccentric 41-...

  16. Searching for extragalactic planets

    OpenAIRE

    Baltz, Edward A.; Gondolo, Paolo

    1999-01-01

    Are there other planetary systems in our Universe? Indirect evidence has been found for planets orbiting other stars in our galaxy: the gravity of orbiting planets makes the star wobble, and the resulting periodic Doppler shifts have been detected for about a dozen stars. But are there planets in other galaxies, millions of light years away? Here we suggest a method to search for extragalactic planetary systems: gravitational microlensing of unresolved stars. This technique may allow us to di...

  17. Exploring Disks Around Planets

    Science.gov (United States)

    Kohler, Susanna

    2017-07-01

    Giant planets are thought to form in circumstellar disks surrounding young stars, but material may also accrete into a smaller disk around the planet. Weve never detected one of these circumplanetary disks before but thanks to new simulations, we now have a better idea of what to look for.Image from previous work simulating a Jupiter-mass planet forming inside a circumstellar disk. The planet has its own circumplanetary disk of accreted material. [Frdric Masset]Elusive DisksIn the formation of giant planets, we think the final phase consists of accretion onto the planet from a disk that surrounds it. This circumplanetary disk is important to understand, since it both regulates the late gas accretion and forms the birthplace of future satellites of the planet.Weve yet to detect a circumplanetary disk thus far, because the resolution needed to spot one has been out of reach. Now, however, were entering an era where the disk and its kinematics may be observable with high-powered telescopes (like the Atacama Large Millimeter Array).To prepare for such observations, we need models that predict the basic characteristics of these disks like the mass, temperature, and kinematic properties. Now a researcher at the ETH Zrich Institute for Astronomy in Switzerland, Judit Szulgyi, has worked toward this goal.Simulating CoolingSzulgyi performs a series of 3D global radiative hydrodynamic simulations of 1, 3, 5, and 10 Jupiter-mass (MJ) giant planets and their surrounding circumplanetary disks, embedded within the larger circumstellar disk around the central star.Density (left column), temperature (center), and normalized angular momentum (right) for a 1 MJ planet over temperatures cooling from 10,000 K (top) to 1,000 K (bottom). At high temperatures, a spherical circumplanetary envelope surrounds the planet, but as the planet cools, the envelope transitions around 64,000 K to a flattened disk. [Szulgyi 2017]This work explores the effects of different planet temperatures and

  18. Theory of Giant Planets

    Science.gov (United States)

    Hubbard, W. B.; Burrows, A.; Lunine, J. I.

    Giant planet research has moved from the study of a handful of solar system objects to that of a class of bodies with dozens of known members. Since the original 1995 discovery of the first extrasolar giant planets (EGPs), the total number of known examples has increased to ~80 (circa November 2001). Current theoretical studies of giant planets emphasize predicted observable properties, such as luminosity, effective temperature, radius, external gravity field, atmospheric composition, and emergent spectra as a function of mass and age. This review focuses on the general theory of hydrogen-rich giant planets; smaller giant planets with the mass and composition of Uranus and Neptune are not covered. We discuss the status of the theory of the nonideal thermodynamics of hydrogen and hydrogen-helium mixtures under the conditions found in giant-planet interiors, and the experimental constraints on it. We provide an overview of observations of extrasolar giant planets and our own giant planets by which the theory can be validated.

  19. Feasibility and benefits of pulsar planet characterization

    Science.gov (United States)

    Nekola Novakova, J.; Petrasek, T.

    2017-09-01

    Planet orbiting neutron stars seem to be rare, but all the more interesting for science due to their origins. Characterizing the composition of pulsar planets could elucidate processes involved in supernova fallback disks, accretion of companion star material, potential survival of planetary cores in the post-MS phase of their stars, and more. However, the small size and unusual spectral distribution of neutron stars make any spectroscopic measurements very difficult if not impossible in the near future. We set to estimate the feasibility of spectroscopy of planets orbiting specifically pulsars, and to review other possible methods of characterization of the planets, such as emissions caused by aurorae. We conclude that spectroscopic characterization of pulsar planets is unlikely to be achieved in the near future, though not entirely impossible, but possible auroral emissions and thermal emissions present more feasible means of at least roughly characterizing planets in pulsar systems. Moreover, they could in theory reveal planets around young pulsars where there is too much timing noise compared to "recycled" millisecond pulsars. While researching pulsar planetary systems could hardly be further from the popular search for "Earth 2.0", it could yield extremely valuable data for planetary science, radio astronomy, astrophysics and other fields, and it could help us answer some fundamental questions about exoplanetary origins and evolutions. For these reasons, we think it worthwhile to pursue this topic.

  20. A Young Three-Planet System in the Hyades

    Science.gov (United States)

    Mann, Andrew; Newton, Elisabeth; Rizzuto, Aaron; Vanderburg, Andrew

    2017-10-01

    Planets are nor born in their final state; instead, before reaching a more mature and stable phase, young planets have their structures, orbits, and atmospheres disrupted by their environment. Early changes in planetary systems can have profound implications for the final configuration of the planets, which makes it critical to study planets during their most formative years (0-1 Gyr). However, most of the known planets have poorly constrained ages or are older than the timescales of interest. In the latest K2 data release we identified a 3-planet system in the Hyades cluster (700 Myr). The smallest of these planets is Earth-sized, creating a unique opportunity to study small, rocky planets while they are still evolving. However, the parameters of this planet are poorly constrained from the K2 light curve, and the ephemeris needs updating. The largest planet should have a large atmospheric scale-height based on similar planets, but could be flat if material in the upper atmosphere has not yet settled. Here we propose Spitzer observations of both planets to significantly improve their parameters, lock the ephemerides well into the era of JWST, take early steps to characterize their atmospheres, and search for expected transit timing variations.

  1. The metallicities of stars with and without transiting planets

    DEFF Research Database (Denmark)

    Buchhave, Lars A.; Latham, David W.

    2015-01-01

    Host star metallicities have been used to infer observational constraints on planet formation throughout the history of the exoplanet field. The giant planet metallicity correlation has now been widely accepted, but questions remain as to whether the metallicity correlation extends to the small...... terrestrial-sized planets. Here, we report metallicities for a sample of 518 stars in the Kepler field that have no detected transiting planets and compare their metallicity distribution to a sample of stars that hosts small planets (). Importantly, both samples have been analyzed in a homogeneous manner...... using the same set of tools (Stellar Parameters Classification tool). We find the average metallicity of the sample of stars without detected transiting planets to be and the sample of stars hosting small planets to be . The average metallicities of the two samples are indistinguishable within...

  2. More Planets in the Hyades Cluster

    Science.gov (United States)

    Kohler, Susanna

    2017-12-01

    A few weeks ago, Astrobites reported on a Neptune-sized planet discovered orbiting a star in the Hyades cluster. A separate study submitted at the same time, however, reveals that there may be even more planets lurking in this system.Thanks, KeplerArtists impression of the Kepler spacecraft and the mapping of the fields of the current K2 mission. [NASA]As we learn about the formation and evolution of planets outside of our own solar system, its important that we search for planets throughout different types of star clusters; observing both old and young clusters, for instance, can tell us about planets in different stages of their evolutionary histories. Luckily for us, we have a tool that has been doing exactly this: the Kepler mission.In true holiday spirit, Kepler is the gift that just keeps on giving. Though two of its reaction wheels have failed, Kepler now as its reincarnation, K2 just keeps detecting more planet transits. Whats more, detailed analysis of past Kepler/K2 data with ever more powerful techniques as well as the addition of high-precision parallaxes for stars from Gaia in the near future ensures that the Kepler data set will continue to reveal new exoplanet transits for many years to come.Image of the Hyades cluster, a star cluster that is only 800 million years old. [NASA/ESA/STScI]Hunting in the Young HyadesTwo studies using K2 data were recently submitted on exoplanet discoveries around EPIC 247589423 in the Hyades cluster, a nearby star cluster that is only 800 million years old. Astrobites reported on the first study in October and discussed details about the newly discovered mini-Neptune presented in that study.The second study, led by Andrew Mann (University of Texas at Austin and NASA Hubble Fellow at Columbia University), was published this week. This study presented a slightly different outcome: the authors detect the presence of not just the one, but three exoplanets orbiting EPIC 247589423.New DiscoveriesMann and collaborators searched

  3. Planets a very short introduction

    CERN Document Server

    Rothery, David A

    2010-01-01

    Planets: A Very Short Introduction demonstrates the excitement, uncertainties, and challenges faced by planetary scientists, and provides an overview of our Solar System and its origins, nature, and evolution. Terrestrial planets, giant planets, dwarf planets and various other objects such as satellites (moons), asteroids, trans-Neptunian objects, and exoplanets are discussed. Our knowledge about planets has advanced over the centuries, and has expanded at a rapidly growing rate in recent years. Controversial issues are outlined, such as What qualifies as a planet? What conditions are required for a planetary body to be potentially inhabited by life? Why does Pluto no longer have planet status? And Is there life on other planets?

  4. BINARY MINOR PLANETS

    Data.gov (United States)

    National Aeronautics and Space Administration — The data set lists orbital and physical properties for well-observed or suspected binary/multiple minor planets including the Pluto system, compiled from the...

  5. Students Discover Unique Planet

    Science.gov (United States)

    2008-12-01

    Three undergraduate students, from Leiden University in the Netherlands, have discovered an extrasolar planet. The extraordinary find, which turned up during their research project, is about five times as massive as Jupiter. This is also the first planet discovered orbiting a fast-rotating hot star. Omega Centauri ESO PR Photo 45a/08 A planet around a hot star The students were testing a method of investigating the light fluctuations of thousands of stars in the OGLE database in an automated way. The brightness of one of the stars was found to decrease for two hours every 2.5 days by about one percent. Follow-up observations, taken with ESO's Very Large Telescope in Chile, confirmed that this phenomenon is caused by a planet passing in front of the star, blocking part of the starlight at regular intervals. According to Ignas Snellen, supervisor of the research project, the discovery was a complete surprise. "The project was actually meant to teach the students how to develop search algorithms. But they did so well that there was time to test their algorithm on a so far unexplored database. At some point they came into my office and showed me this light curve. I was completely taken aback!" The students, Meta de Hoon, Remco van der Burg, and Francis Vuijsje, are very enthusiastic. "It is exciting not just to find a planet, but to find one as unusual as this one; it turns out to be the first planet discovered around a fast rotating star, and it's also the hottest star found with a planet," says Meta. "The computer needed more than a thousand hours to do all the calculations," continues Remco. The planet is given the prosaic name OGLE2-TR-L9b. "But amongst ourselves we call it ReMeFra-1, after Remco, Meta, and myself," says Francis. The planet was discovered by looking at the brightness variations of about 15 700 stars, which had been observed by the OGLE survey once or twice per night for about four years between 1997 and 2000. Because the data had been made public

  6. SDSS-III MARVELS Planet Candidate RV Follow-up

    Science.gov (United States)

    Ge, Jian; Thomas, Neil; Ma, Bo; Li, Rui; SIthajan, Sirinrat

    2014-02-01

    Planetary systems, discovered by the radial velocity (RV) surveys, reveal strong correlations between the planet frequency and stellar properties, such as metallicity and mass, and a greater diversity in planets than found in the solar system. However, due to the sample sizes of extant surveys (~100 to a few hundreds of stars) and their heterogeneity, many key questions remained to be addressed: Do metal poor stars obey the same trends for planet occurrence as metal rich stars? What is the distribution of giant planets around intermediate- mass stars and binaries? Is the ``planet desert'' within 0.6 AU in the planet orbital distribution of intermediate-mass stars real? The MARVELS survey has produced the largest homogeneous RV measurements of 3300 V=7.6-12 FGK stars. The latest data pipeline effort at UF has been able to remove long term systematic errors suffered in the earlier data pipeline. 18 high confident giant planet candidates have been identified among newly processed data. We propose to follow up these giant planet candidates with the KPNO EXPERT instrument to confirm the detection and also characterize their orbits. The confirmed planets will be used to measure occurrence rates, distributions and multiplicity of giants planets around F,G,K stars with a broad range of mass (~0.6-2.5 M_⊙) and metallicity ([Fe/H]~-1.5-0.5). The well defined MARVELS survey cadence allows robust determinations of completeness limits for rigorously testing giant planet formation theories and constraining models.

  7. The planet Mercury (1971)

    Science.gov (United States)

    1972-01-01

    The physical properties of the planet Mercury, its surface, and atmosphere are presented for space vehicle design criteria. The mass, dimensions, mean density, and orbital and rotational motions are described. The gravity field, magnetic field, electromagnetic radiation, and charged particles in the planet's orbit are discussed. Atmospheric pressure, temperature, and composition data are given along with the surface composition, soil mechanical properties, and topography, and the surface electromagnetic and temperature properties.

  8. Venusians: the Planet Venus in the 18th-Century Extraterrestrial Life Debate

    National Research Council Canada - National Science Library

    Dunér, David

    2013-01-01

    ..., then the assumption of life on other planets became much less far-fetched, and, in general there were no actual differences between Earth and Venus, since both planets orbited the Sun, were of similar size...

  9. MESSENGER: Exploring the Innermost Planet

    Science.gov (United States)

    Solomon, S. C.

    2011-12-01

    One of Earth's closest planetary neighbors, Mercury remained comparatively unexplored for the more than three decades that followed the three flybys of the innermost planet by the Mariner 10 spacecraft in 1974-75. Mariner 10 imaged 45% of Mercury's surface at about 1 km/pixel average resolution, confirmed Mercury's anomalously high bulk density and implied large fractional core size, discovered Mercury's internal magnetic field, documented that H and He are present in the planet's tenuous exosphere, and made the first exploration of Mercury's magnetosphere and solar wind environment. Ground-based astronomers later reported Na, K, and Ca in Mercury's exosphere; the presence of deposits in the floors of polar craters having radar characteristics best matched by water ice; and strong evidence from the planet's forced libration amplitude that Mercury has a fluid outer core. Spacecraft exploration of Mercury resumed with the selection for flight, under NASA's Discovery Program, of the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) mission. Launched in 2004, MESSENGER flew by the innermost planet three times in 2008-2009 en route to becoming the first spacecraft to orbit Mercury in March of this year. MESSENGER's first chemical remote sensing measurements of Mercury's surface indicate that the planet's bulk silicate fraction differs from those of the other inner planets, with a low-Fe surface composition intermediate between basalts and ultramafic rocks and best matched among terrestrial rocks by komatiites. Moreover, surface materials are richer in the volatile constituents S and K than predicted by most planetary formation models. Global image mosaics and targeted high-resolution images (to resolutions of 10 m/pixel) reveal that Mercury experienced globally extensive volcanism, including large expanses of plains emplaced as flood lavas and widespread examples of pyroclastic deposits likely emplaced during explosive eruptions of volatile

  10. Optimizing the TESS Planet Finding Pipeline

    Science.gov (United States)

    Chitamitara, Aerbwong; Smith, Jeffrey C.; Tenenbaum, Peter; TESS Science Processing Operations Center

    2017-10-01

    The Transiting Exoplanet Survey Satellite (TESS) is a new NASA planet finding all-sky survey that will observe stars within 200 light years and 10-100 times brighter than that of the highly successful Kepler mission. TESS is expected to detect ~1000 planets smaller than Neptune and dozens of Earth size planets. As in the Kepler mission, the Science Processing Operations Center (SPOC) processing pipeline at NASA Ames Research center is tasked with calibrating the raw pixel data, generating systematic error corrected light curves and then detecting and validating transit signals. The Transiting Planet Search (TPS) component of the pipeline must be modified and tuned for the new data characteristics in TESS. For example, due to each sector being viewed for as little as 28 days, the pipeline will be identifying transiting planets based on a minimum of two transit signals rather than three, as in the Kepler mission. This may result in a significantly higher false positive rate. The study presented here is to measure the detection efficiency of the TESS pipeline using simulated data. Transiting planets identified by TPS are compared to transiting planets from the simulated transit model using the measured epochs, periods, transit durations and the expected detection statistic of injected transit signals (expected MES). From the comparisons, the recovery and false positive rates of TPS is measured. Measurements of recovery in TPS are then used to adjust TPS configuration parameters to maximize the planet recovery rate and minimize false detections. The improvements in recovery rate between initial TPS conditions and after various adjustments will be presented and discussed.

  11. Protostars and Planets VI

    Science.gov (United States)

    Beuther, Henrik; Klessen, Ralf S.; Dullemond, Cornelis P.; Henning, Thomas

    The Protostars and Planets book and conference series has been a long-standing tradition that commenced with the first meeting led by Tom Gehrels and held in Tucson, Arizona, in 1978. The goal then, as it still is today, was to bridge the gap between the fields of star and planet formation as well as the investigation of planetary systems and planets. As Tom Gehrels stated in the preface to the first Protostars and Planets book, "Cross-fertilization of information and understanding is bound to occur when investigators who are familiar with the stellar and interstellar phases meet with those who study the early phases of solar system formation." The central goal remained the same for the subsequent editions of the books and conferences Protostars and Planets II in 1984, Protostars and Planets III in 1990, Protostars and Planets IV in 1998, and Protostars and Planets V in 2005, but has now been greatly expanded by the flood of new discoveries in the field of exoplanet science. The original concept of the Protostars and Planets series also formed the basis for the sixth conference in the series, which took place on July 15-20, 2013. It was held for the first time outside of the United States in the bustling university town of Heidelberg, Germany. The meeting attracted 852 participants from 32 countries, and was centered around 38 review talks and more than 600 posters. The review talks were expanded to form the 38 chapters of this book, written by a total of 250 contributing authors. This Protostars and Planets volume reflects the current state-of-the-art in star and planet formation, and tightly connects the fields with each other. It is structured into four sections covering key aspects of molecular cloud and star formation, disk formation and evolution, planetary systems, and astrophysical conditions for life. All poster presentations from the conference can be found at www.ppvi.org. In the eight years that have passed since the fifth conference and book in the

  12. Masses, radii, and orbits of small Kepler planets

    DEFF Research Database (Denmark)

    Marcy, Geoffrey W.; Isaacson, Howard; Howard, Andrew W.

    2014-01-01

    We report on the masses, sizes, and orbits of the planets orbiting 22 Kepler stars. There are 49 planet candidates around these stars, including 42 detected through transits and 7 revealed by precise Doppler measurements of the host stars. Based on an analysis of the Kepler brightness measurements...

  13. Planets in a Room

    Science.gov (United States)

    Giacomini, l.; Aloisi, F.; De Angelis, I.

    2017-09-01

    Teaching planetary science using a spherical projector to show the planets' surfaces is a very effective but usually very expensive idea. Whatsmore, it usually assumes the availability of a dedicated space and a trained user. "Planets in a room" is a prototypal low cost version of a small, spherical projector that teachers, museum, planetary scientists and other individuals can easily build and use on their own, to show and teach the planets The project of "Planets in a Room" was made by the italian non-profit association Speak Science with the collaboration of INAF-IAPS of Rome and the Roma Tre University (Dipartimento di Matematica e Fisica). This proposal was funded by the Europlanet Outreach Funding Scheme in 2016. "Planets in a room" will be presented during EPSC 2017 to give birth to the second phase of the project, when the outreach and research community will be involved and schools from all over Europe will be invited to participate with the aim of bringing planetary science to a larger audience.

  14. Recipes for planet formation

    Science.gov (United States)

    Meyer, Michael R.

    2009-11-01

    Anyone who has ever used baking soda instead of baking powder when trying to make a cake knows a simple truth: ingredients matter. The same is true for planet formation. Planets are made from the materials that coalesce in a rotating disk around young stars - essentially the "leftovers" from when the stars themselves formed through the gravitational collapse of rotating clouds of gas and dust. The planet-making disk should therefore initially have the same gas-to-dust ratio as the interstellar medium: about 100 to 1, by mass. Similarly, it seems logical that the elemental composition of the disk should match that of the star, reflecting the initial conditions at that particular spot in the galaxy.

  15. Future prospects for the detection and characterization of extrasolar planets

    Directory of Open Access Journals (Sweden)

    Lunine J.I.

    2010-12-01

    Full Text Available Several distinctly different techniques have detected almost 500 planets orbiting around main-sequence stars, 45 multiple planet systems, and a number of extrasolar planets have been the subject of direct study. Hundreds of other “candidate” planets detected by the Kepler spacecraft await confirmation of their existence. Planets are thus common phenomena around stars, and the prospects seem good in the next few years for establishing statistics on the occurrence of Earth-sized planets. Extension of the most successful technique of Doppler spectroscopy in sensitivity to detect Earth-mass planets around Sun-like stars will be limited by the noise generated by the stellar photospheres themselves. The James Webb Space Telescope will have the capability to measure atmospheric abundances of certain gases and of liquid water on extrasolar planets, including “superEarths” within a factor of two of the radius of the Earth. The ultimate goal of measuring the atmospheric composition of an Earth-sized planet orbiting at 1 AU around a star like the Sun remains a daunting challenge that is perhaps twenty years in the future.

  16. Location of Planet X

    Energy Technology Data Exchange (ETDEWEB)

    Harrington, R.S.

    1988-10-01

    Observed positions of Uranus and Neptune along with residuals in right ascension and declination are used to constrain the location of a postulated tenth planet. The residuals are converted into residuals in ecliptic longitude and latitude. The results are then combined into seasonal normal points, producing average geocentric residuals spaced slightly more than a year apart that are assumed to represent the equivalent heliocentric average residuals for the observed oppositions. Such a planet is found to most likely reside in the region of Scorpius, with considerably less likelihood that it is in Taurus. 8 references.

  17. GAP CLEARING BY PLANETS IN A COLLISIONAL DEBRIS DISK

    Energy Technology Data Exchange (ETDEWEB)

    Nesvold, Erika R. [Department of Physics, University of Maryland Baltimore County 1000 Hilltop Circle Baltimore, MD 21250 (United States); Kuchner, Marc J., E-mail: Erika.Nesvold@umbc.edu, E-mail: Marc.Kuchner@nasa.gov [NASA Goddard Space Flight Center Exoplanets and Stellar Astrophysics Laboratory, Code 667 Greenbelt, MD 21230 (United States)

    2015-01-10

    We apply our 3D debris disk model, SMACK, to simulate a planet on a circular orbit near a ring of planetesimals that are experiencing destructive collisions. Previous simulations of a planet opening a gap in a collisionless debris disk have found that the width of the gap scales as the planet mass to the 2/7th power (α = 2/7). We find that gap sizes in a collisional disk still obey a power law scaling with planet mass, but that the index α of the power law depends on the age of the system t relative to the collisional timescale t {sub coll} of the disk by α = 0.32(t/t {sub coll}){sup –0.04}, with inferred planet masses up to five times smaller than those predicted by the classical gap law. The increased gap sizes likely stem from the interaction between collisions and the mean motion resonances near the chaotic zone. We investigate the effects of the initial eccentricity distribution of the disk particles and find a negligible effect on the gap size at Jovian planet masses, since collisions tend to erase memory of the initial particle eccentricity distributions. Finally, we find that the presence of Trojan analogs is a potentially powerful diagnostic of planets in the mass range ∼1-10 M {sub Jup}. We apply our model to place new upper limits on planets around Fomalhaut, HR 4796 A, HD 202628, HD 181327, and β Pictoris.

  18. Planets and satellites galore

    Science.gov (United States)

    Marsden, B. G.

    1980-10-01

    The facts and controversies surrounding the discoveries of Uranus, Neptune, Pluto and their satellites are reviewed. Earth-approaching and earth-crossing minor planets are discussed with attention to the work of Helin and Giclas. The problems attending satellite discoveries are examined, and the criteria for 1978 P 1 is evaluated.

  19. The Planet Venus

    Science.gov (United States)

    1979-01-01

    Physical features of the planet Venus, including its rotational characteristics and the surface properties observed by NASA's Deep Space Network radar scanner and Soviet spacecraft are examined. Atmospheric composition and circulation and the nature of the Venus clouds are also discussed in this instructional pamphlet. A reading list and student projects are included.

  20. Planets and Pucks.

    Science.gov (United States)

    Brueningsen, Christopher; Krawiec, Wesley

    1993-01-01

    Presents a simple activity designed to allow students to experimentally verify Kepler's second law, sometimes called the law of equal areas. It states that areas swept out by a planet as it orbits the Sun are equal for equal time intervals. (PR)

  1. The formation of planets in circumbinary discs

    Science.gov (United States)

    Pelupessy, F. I.; Portegies Zwart, S.

    2013-02-01

    We examine the formation of planets around binary stars in light of the recently discovered systems Kepler 16, 34 and 35. We conduct hydrodynamical simulations of self-gravitating discs around binary systems. The selected binary and disc parameters are chosen consistent with observed systems. The discs are evolved until they settle in a quasi-equilibrium and the resulting systems are compared with the parameters of Kepler 16, 34 and 35. We find a close correspondence of the peak density at the inner disc gap and the orbit of the observed planets. We conclude, based on our simulations, that the orbits of the observed Kepler planets are determined by the size of the inner disc gap which for these systems results from the binary driving. This mediates planet formation either through the density enhancement or through planetary trapping at the density gradient inversion in the inner disc. For all three systems the current eccentricity of the planetary orbit is less than the disc eccentricity in the simulations. This, together with the long-term stability of the orbits argues against in situ formation (e.g. a direct collapse scenario of the material in the ring). Conducting additional simulations of systems with a wider range of parameters (taken from a survey of eclipsing binaries), we find that the planet semimajor axis and binary eccentricity in such a scenario should be tightly correlated providing an observational test of this formation mechanism.

  2. Trapping Dust to Form Planets

    Science.gov (United States)

    Kohler, Susanna

    2017-10-01

    Kraus (University of Exeter) in a recent publication. Kraus and collaborators show that the protoplanetary disk of V1247 Orionis contains a ring-shaped, asymmetric inner disk component, as well as a sharply confined crescent structure. These structures are consistent with the morphologies expected from theoretical models of vortex formation in disks.Kraus and collaborators propose the following picture: an early planet is orbiting at 100 AU within the disk, generating a one-armed spiral arm as material feeds the protoplanet. As the protoplanet orbits, it clears a gap between the ring and the crescent, and it simultaneously triggers two vortices, visible as the crescent and the bright asymmetry in the ring. These vortices are then able to trap millimeter-sized particles.Gas column density of the authors radiation-hydrodynamic simulation of V1247 Orioniss disk. [Kraus et al. 2017]The authors run detailed hydrodynamics simulations of this scenario and compare them (as well as alternative theories) to the ALMA observations of V1247 Orionis. The simulations support their model, producing sample scattered-light images thatmatchwell the one-armed spiral observed in previous scattered-light images of the disk.How can we confirm V1247 Orionis providesan example of dust-trapping vortices? One piece of supporting evidence would be the discovery of the protoplanet that Kraus and collaborators theorize triggered the potential vortices in this disk. Future deeper ALMA imaging may make this possible, helping to confirm our picture of how dust builds into planets.CitationStefan Kraus et al 2017 ApJL 848 L11. doi:10.3847/2041-8213/aa8edc

  3. Planets in Binary Star Systems

    CERN Document Server

    Haghighipour, Nader

    2010-01-01

    The discovery of extrasolar planets over the past decade has had major impacts on our understanding of the formation and dynamical evolution of planetary systems. There are features and characteristics unseen in our solar system and unexplainable by the current theories of planet formation and dynamics. Among these new surprises is the discovery of planets in binary and multiple-star systems. The discovery of such "binary-planetary" systems has confronted astrodynamicists with many new challenges, and has led them to re-examine the theories of planet formation and dynamics. Among these challenges are: How are planets formed in binary star systems? What would be the notion of habitability in such systems? Under what conditions can binary star systems have habitable planets? How will volatiles necessary for life appear on such planets? This volume seeks to gather the current research in the area of planets in binary and multistar systems and to familiarize readers with its associated theoretical and observation...

  4. Planet Detection: The Kepler Mission

    Science.gov (United States)

    Jenkins, Jon M.; Smith, Jeffrey C.; Tenenbaum, Peter; Twicken, Joseph D.; Van Cleve, Jeffrey

    2012-03-01

    The search for exoplanets is one of the hottest topics in astronomy and astrophysics in the twenty-first century, capturing the public's attention as well as that of the astronomical community. This nascent field was conceived in 1989 with the discovery of a candidate planetary companion to HD114762 [35] and was born in 1995 with the discovery of the first extrasolar planet 51 Peg-b [37] orbiting a main sequence star. As of March, 2011, over 500 exoplanets have been discovered* and 106 are known to transit or cross their host star, as viewed from Earth. Of these transiting planets, 15 have been announced by the Kepler Mission, which was launched into an Earth-trailing, heliocentric orbit in March, 2009 [1,4,6,15,18,20,22,31,32,34,36,43]. In addition, over 1200 candidate transiting planets have already been detected by Kepler [5], and vigorous follow-up observations are being conducted to vet these candidates. As the false-positive rate for Kepler is expected to be quite low [39], Kepler has effectively tripled the number of known exoplanets. Moreover, Kepler will provide an unprecedented data set in terms of photometric precision, duration, contiguity, and number of stars. Kepler's primary science objective is to determine the frequency of Earth-size planets transiting their Sun-like host stars in the habitable zone, that range of orbital distances for which liquid water would pool on the surface of a terrestrial planet such as Earth, Mars, or Venus. This daunting task demands an instrument capable of measuring the light output from each of over 100,000 stars simultaneously with an unprecedented photometric precision of 20 parts per million (ppm) at 6.5-h intervals. The large number of stars is required because the probability of the geometrical alignment of planetary orbits that permit observation of transits is the ratio of the size of the star to the size of the planetary orbit. For Earth-like planets in 1-astronomical unit (AU) orbits† about sun-like stars

  5. Classifying Planets: Nature vs. Nurture

    Science.gov (United States)

    Beichman, Charles A.

    2009-05-01

    The idea of a planet was so simple when we learned about the solar system in elementary school. Now students and professional s alike are faced with confusing array of definitions --- from "Brown Dwarfs” to "Super Jupiters", from "Super Earths” to "Terrestrial Planets", and from "Planets” to "Small, Sort-of Round Things That Aren't Really Planets". I will discuss how planets might be defined by how they formed, where they are found, or by the life they might support.

  6. Probing LSST's Ability to Detect Planets Around White Dwarfs

    Science.gov (United States)

    Cortes, Jorge; Kipping, David

    2018-01-01

    Over the last four years more than 2,000 planets outside our solar system have been discovered, motivating us to search for and characterize potentially habitable worlds. Most planets orbit Sun-like stars, but more exotic stars can also host planets. Debris disks and disintegrating planetary bodies have been detected around white dwarf stars, the inert, Earth-sized cores of once-thriving stars like our Sun. These detections are clues that planets may exist around white dwarfs. Due to the faintness of white dwarfs and the potential rarity of planets around them, a vast survey is required to have a chance at detecting these planetary systems. The Large Synoptic Survey Telescope (LSST), scheduled to commence operations in 2023, will image the entire southern sky every few nights for 10 years, providing our first real opportunity to detect planets around white dwarfs. We characterized LSST’s ability to detect planets around white dwarfs through simulations that incorporate realistic models for LSST’s observing strategy and the white dwarf distribution within the Milky Way galaxy. This was done through the use of LSST's Operations Simulator (OpSim) and Catalog Simulator (CatSim). Our preliminary results indicate that, if all white dwarfs were to possess a planet, LSST would yield a detection for every 100 observed white dwarfs. In the future, a larger set of ongoing simulations will help us quantify the number of planets LSST could potentially find.

  7. Transit visibility zones of the Solar system planets

    Science.gov (United States)

    Wells, R.; Poppenhaeger, K.; Watson, C. A.; Heller, R.

    2018-01-01

    The detection of thousands of extrasolar planets by the transit method naturally raises the question of whether potential extrasolar observers could detect the transits of the Solar system planets. We present a comprehensive analysis of the regions in the sky from where transit events of the Solar system planets can be detected. We specify how many different Solar system planets can be observed from any given point in the sky, and find the maximum number to be three. We report the probabilities of a randomly positioned external observer to be able to observe single and multiple Solar system planet transits; specifically, we find a probability of 2.518 per cent to be able to observe at least one transiting planet, 0.229 per cent for at least two transiting planets, and 0.027 per cent for three transiting planets. We identify 68 known exoplanets that have a favourable geometric perspective to allow transit detections in the Solar system and we show how the ongoing K2 mission will extend this list. We use occurrence rates of exoplanets to estimate that there are 3.2 ± 1.2 and 6.6^{+1.3}_{-0.8} temperate Earth-sized planets orbiting GK and M dwarf stars brighter than V = 13 and 16, respectively, that are located in the Earth's transit zone.

  8. "Osiris"(HD209458b), an Evaporating Planet

    Science.gov (United States)

    Vidal-Madjar, A.; Lecavelier des Etangs, A.

    2004-12-01

    Three transits of the planet orbiting the solar type star HD 209458 were observed in the far UV at the wavelength of the HI Lyα line. The planet size at this wavelength is equal to 4.3 RJup, i.e. larger than the planet Roche radius (3.6 RJup). Absorbing hydrogen atoms were found to be blueshifted by up to --130 km.s-1, exceeding the planet escape velocity. This implies that hydrogen atoms are escaping this ``hot Jupiter'' planet. An escape flux of ⪆1010 g.s-1 is needed to explain the observations. Taking into account the tidal forces and the temperature rise expected in the upper atmosphere, theoretical evaluations are in good agreement with the observed rate. Lifetime of planets closer to their star could be shorter than stellar lifetimes suggesting that this evaporating phenomenon may explain the lack of planets with very short orbital distance. This evaporating planet could be represented by the Egyptian god ``Osiris'' cut into pieces and having lost one of them. This would give us a much easier way to name that planet and replace the unpleasant ``HD209458b'' name used so far.

  9. Trojan twin planets

    Science.gov (United States)

    Dvorak, R.; Loibnegger, B.; Schwarz, R.

    2017-03-01

    The Trojan asteroids are moving in the vicinity of the stable Lagrange points L_4 and L_5 of the gas giants Jupiter, Uranus and Neptune. Their motion can be described and understood with the aid of the restricted three-body problem. As an extension of this problem we investigate how stable motion close to the Lagrange points of two massive bodies can exist. This configuration can be described as the Trojan Twin Problem when we regard the two additional bodies as having a mass significantly smaller than the the two primary bodies: a star in the center (m_1) and an additional Jupiter-like mass (m_2). Using this 4-body problem we have undertaken numerical investigations concerning possible stable "twin orbits". However, these two bodies (m_3 and m_4) in Trojan-like orbits may have quite different masses. We decided to choose 6 different scenaria for this problem: as primary body, m2, we have taken a Jupiter-like planet, a Saturn-like one, and a super-Earth with 10 Earthmasses (m_{Earth}) respectively. As quasi twin planets, we have used different mass ratios namely objects for m3 and m4 from 10m_{Earth} to Moon like ones. We found different stable configurations depending on the involved masses and the initial distances between the twins (always close to the Lagrange point). Although the formation of such a configuration seems to be not very probable we should not exclude that it exists regarding the huge number of planets even in our own galaxy. This model is of special interest when the most massive planet (m_2) is moving on an orbit in the habitable zone around a main sequence star. One can use our results of stable orbits of Trojan Twin Planets (or asteroids) for extrasolar systems having as second primary a Jupiter-like, a Saturn-like or a super-Earth like planet around a star similar to our Sun.

  10. Planet formation around millisecond pulsars

    Science.gov (United States)

    Banit, Menashe; Ruderman, Malvin; Shaham, Jacob

    1993-01-01

    We present a model for the formation of planets in circular orbits around millisecond pulsars. We propose that the planets originate from a circumbinary excretion disk around a binary millisecond pulsar and show how physical conditions in such a disk lead to the eventual formation of planets.

  11. Extrasolar Planets in the Classroom

    Science.gov (United States)

    George, Samuel J.

    2011-01-01

    The field of extrasolar planets is still, in comparison with other astrophysical topics, in its infancy. There have been about 300 or so extrasolar planets detected and their detection has been accomplished by various different techniques. Here we present a simple laboratory experiment to show how planets are detected using the transit technique.…

  12. Alpha Elements' Effects on Planet Formation and the Hunt for Extragalactic Planets

    Science.gov (United States)

    Penny, Matthew; Rodriguez, Joseph E.; Beatty, Thomas; Zhou, George

    2018-01-01

    A star's likelihood of hosting a giant planet is well known to be strongly dependent on metallicity. However, little is known about what elements cause this correlation (e.g. bulk metals, iron, or alpha elements such as silicon and oxygen). This is likely because most planet searches target stars in the Galactic disk, and due to Galactic chemical evolution, alpha element abundances are themselves correlated with metallicity within a population. We investigate the feasibility of simultaneous transiting planet search towards the alpha-poor Sagittarius dwarf galaxy and alpha-rich Galactic bulge in a single field of view of DECam, that would enable a comparative study of planet frequency over an [alpha/Fe] baseline of ~0.4 dex. We show that a modestly sized survey could detect planet candidates in both populations, but that false positive rejection in Sgr Dwarf may be prohibitively expensive. Conversely, two-filter survey observations alone would be sufficient to rule out a large fraction of bulge false positives, enabling statistical validation of candidates with a modest follow-up investment. Although over a shorter [alpha/Fe] baseline, this survey would provide a test of whether it is alpha or iron that causes the planet metallicity correlation.

  13. The Nature of Inhabited Planets and their Inhabitants

    CERN Document Server

    Simpson, Fergus

    2016-01-01

    Earth-like planets are expected to provide the greatest opportunity for the detection of life beyond the Solar System. This notion stems from an assumption that the Earth constitutes a simple random sample amongst inhabited planets. However, in the event that other intelligent species exist, our planet should not be considered a fair sample. Just as a person's country of origin is a biased sample among countries, so too their planet of origin is a biased sample among planets. The strength of this effect can be substantial: over 98% of the world's population live in a country larger than the median. Any variable which influences either the population size or birth rate is susceptible to selection bias. In the context of a simple model where the mean population density is invariant to planet size, we infer that an inhabited planet selected at random (such as our nearest neighbour) has a radius r<1.2 r_Earth (95% confidence bound). If the range of habitable radii is sufficiently broad, most inhabited planets ...

  14. The Scattering Outcomes of Kepler Circumbinary Planets: Planet Mass Ratio

    Energy Technology Data Exchange (ETDEWEB)

    Gong, Yan-Xiang; Ji, Jianghui, E-mail: yxgong@pmo.ac.cn, E-mail: jijh@pmo.ac.cn [CAS Key Laboratory of Planetary Sciences, Purple Mountain Observatory, Chinese Academy of Sciences, Nanjing 210008 (China)

    2017-11-01

    Recent studies reveal that the free eccentricities of Kepler-34b and Kepler-413b are much larger than their forced eccentricities, implying that scattering events may take place in their formation. The observed orbital configuration of Kepler-34b cannot be well reproduced in disk-driven migration models, whereas a two-planet scattering scenario can play a significant role of shaping the planetary configuration. These studies indicate that circumbinary planets discovered by Kepler may have experienced scattering process. In this work, we extensively investigate the scattering outcomes of circumbinary planets focusing on the effects of planet mass ratio . We find that the planetary mass ratio and the the initial relative locations of planets act as two important parameters that affect the eccentricity distribution of the surviving planets. As an application of our model, we discuss the observed orbital configurations of Kepler-34b and Kepler-413b. We first adopt the results from the disk-driven models as the initial conditions, then simulate the scattering process that occurs in the late evolution stage of circumbinary planets. We show that the present orbital configurations of Kepler-34b and Kepler-413b can be well reproduced when considering a two unequal-mass planet ejection model. Our work further suggests that some of the currently discovered circumbinary single-planet systems may be survivors of original multiple-planet systems. The disk-driven migration and scattering events occurring in the late stage both play an irreplaceable role in sculpting the final systems.

  15. Giant Planets Can Act as Stabilizing Agents on Debris Disks

    Energy Technology Data Exchange (ETDEWEB)

    Muñoz-Gutiérrez, M. A.; Pichardo, B.; Peimbert, A., E-mail: mmunoz.astro@gmail.com [Instituto de Astronomía, Universidad Nacional Autónoma de México, Apdo. postal 70-264 Ciudad Universitaria, México (Mexico)

    2017-07-01

    We have explored the evolution of a cold debris disk under the gravitational influence of dwarf-planet-sized objects (DPs), both in the presence and absence of an interior giant planet. Through detailed long-term numerical simulations, we demonstrate that when the giant planet is not present, DPs can stir the eccentricities and inclinations of disk particles, in linear proportion to the total mass of the DPs; on the other hand, when the giant planet is included in the simulations, the stirring is approximately proportional to the mass squared. This creates two regimes: below a disk mass threshold (defined by the total mass of DPs), the giant planet acts as a stabilizing agent of the orbits of cometary nuclei, diminishing the effect of the scatterers; above the threshold, the giant contributes to the dispersion of the particles.

  16. CoRoT’s first seven planets: An overview*

    Directory of Open Access Journals (Sweden)

    Barge P.

    2011-07-01

    Full Text Available The up to 150 day uninterrupted high-precision photometry of about 100000 stars – provided so far by the exoplanet channel of the CoRoT space telescope – gave a new perspective on the planet population of our galactic neighbourhood. The seven planets with very accurate parameters widen the range of known planet properties in almost any respect. Giant planets have been detected at low metallicity, rapidly rotating and active, spotted stars. CoRoT-3 populated the brown dwarf desert and closed the gap of measured physical properties between standard giant planets and very low mass stars. CoRoT extended the known range of planet masses down-to 5 Earth masses and up to 21 Jupiter masses, the radii to less than 2 Earth radii and up to the most inflated hot Jupiter found so far, and the periods of planets discovered by transits to 9 days. Two CoRoT planets have host stars with the lowest content of heavy elements known to show a transit hinting towards a different planet-host-star-metallicity relation then the one found by radial-velocity search programs. Finally the properties of the CoRoT-7b prove that terrestrial planets with a density close to Earth exist outside the Solar System. The detection of the secondary transit of CoRoT-1 at the 10−5-level and the very clear detection of the 1.7 Earth radii of CoRoT-7b at 3.5 10−4 relative flux are promising evidence of CoRoT being able to detect even smaller, Earth sized planets.

  17. Observing the Spectra of MEarth and TRAPPIST Planets with JWST

    Science.gov (United States)

    Morley, Caroline; Kreidberg, Laura; Rustamkulov, Zafar; Robinson, Tyler D.; Fortney, Jonathan J.

    2017-10-01

    During the past two years, nine planets close to Earth in radius have been discovered around nearby M dwarfs cooler than 3300 K. These planets include the 7 planets in the TRAPPIST-1 system and two planets discovered by the MEarth survey, GJ 1132b and LHS 1140b (Dittmann et al. 2017; Berta-Thompson et al. 2015; Gillon et al. 2017). These planets are the smallest planets discovered to date that will be amenable to atmospheric characterization with JWST. They span equilibrium temperatures from ˜130 K to >500 K, and radii from 0.7 to 1.43 Earth radii. Some of these planets orbit as distances potentially amenable to surface liquid water, though the actual surface temperatures will depend strongly on the albedo of the planet and the thickness and composition of its atmosphere. The stars they orbit also vary in activity levels, from the quiet LHS 1140b host star to the more active TRAPPIST-1 host star. This set of planets will form the testbed for our first chance to study the diversity of atmospheres around Earth-sized planets. Here, we will present model spectra of these 9 planets, varying the composition and the surface pressure of the atmosphere. We base our elemental compositions on three outcomes of planetary atmosphere evolution in our own solar system: Earth, Titan, and Venus. We calculate the molecular compositions in chemical equilibrium. We present both thermal emission spectra and transmission spectra for each of these objects, and make predictions for the observability of these spectra with different instrument modes with JWST.

  18. Formation of Outer Planets: Overview

    Science.gov (United States)

    Lissauer, Jack

    2003-01-01

    An overview of current theories of planetary formation, with emphasis on giant planets is presented. The most detailed models are based upon observation of our own Solar System and of young stars and their environments. Terrestrial planets are believe to grow via pairwise accretion until the spacing of planetary orbits becomes large enough that the configuration is stable for the age of the system. According to the prevailing core instability model, giant planets begin their growth by the accumulation of small solid bodies, as do terrestrial planets. However, unlike terrestrial planets, the growing giant cores become massive enough that they are able to accumulate substantial amounts of gas before the protoplanetary disk disspates. The primary questions regarding the core instability model is whether planets with small cores can accrete gaseous enveloples within the lifetimes of gaseous protoplanetary disks. The main alternative giant planet formation model is the disk instability model, in which gaseous planets form directly via gravitational instabilities within protoplanetary disks. Formation of giant planets via gas instability has never been demonstrated for realistic disk conditions. Moreover, this model has difficulty explaining the supersolar abundances of heavy elements in Jupiter and Saturn, and it does not explain the orgin of planets like Uranus and Neptune.

  19. Almost All of Kepler's Multiple-planet Candidates Are Planets

    OpenAIRE

    Lissauer, Jack J.; Marcy, Geoffrey W.; Rowe, Jason F.; Bryson, Stephen T.; Adams, Elisabeth; Buchhave, Lars A.; Ciardi, David R.; Cochran, William D.; Fabrycky, Daniel C.; Ford, Eric B.; Fressin, Francois; Geary, John; Gilliland, Ronald L.; Holman, Matthew J.; Howell, Steve B.

    2012-01-01

    We present a statistical analysis that demonstrates that the overwhelming majority of Kepler candidate multiple transiting systems (multis) indeed represent true, physically associated transiting planets. Binary stars provide the primary source of false positives among Kepler planet candidates, implying that false positives should be nearly randomly distributed among Kepler targets. In contrast, true transiting planets would appear clustered around a smaller number of Kepler targets if detect...

  20. Do planets remember how they formed?

    Science.gov (United States)

    Kipping, David

    2018-01-01

    One of the most directly observable features of a transiting multiplanet system is their size-ordering when ranked in orbital separation. Kepler has revealed a rich diversity of outcomes, from perfectly ordered systems, like Kepler-80, to ostensibly disordered systems, like Kepler-20. Under the hypothesis that systems are born via preferred formation pathways, one might reasonably expect non-random size-orderings reflecting these processes. However, subsequent dynamical evolution, often chaotic and turbulent in nature, may erode this information and so here we ask - do systems remember how they formed? To address this, we devise a model to define the entropy of a planetary system's size-ordering, by first comparing differences between neighbouring planets and then extending to accommodate differences across the chain. We derive closed-form solutions for many of the microstate occupancies and provide public code with look-up tables to compute entropy for up to 10-planet systems. All three proposed entropy definitions exhibit the expected property that their credible interval increases with respect to a proxy for time. We find that the observed Kepler multis display a highly significant deficit in entropy compared to a randomly generated population. Incorporating a filter for systems deemed likely to be dynamically packed, we show that this result is robust against the possibility of missing planets too. Put together, our work establishes that Kepler systems do indeed remember something of their younger years and highlights the value of information theory for exoplanetary science.

  1. A Ninth Planet in Our Solar System?

    Science.gov (United States)

    Kohler, Susanna

    2016-01-01

    The recent discovery that the orbits of some Kuiper belt objects (KBOs) share properties has proved puzzling. A pair of scientists have now proposed a bold explanation: there may be a planet-sized object yet undetected in our solar system.Mysterious ClusteringKBOs, the population of mainly small objects beyond Neptune, have proven an especially interesting subject of study in the last decade as many small, distant bodies (such as Eris, the object that led to the demotion of Pluto to dwarf planet) have been discovered.Previous studies have recently discovered that some especially distant KBOs those that orbit with semimajor axes of a 150 AU, nearly four times that of Pluto all cross the ecliptic at a similar phase in their elliptical trajectories. This is unexpected, since gravitational tugs from the giant planets should have randomized this parameter over our solar systems multi-billion-year lifespan.Physical alignment of the orbits of Kuiper belt objects with a 250 AU (and two objects with a 150 AU that are dynamically stable). [Batygin Brown 2016]Two scientists at California Institute of Technology, Konstantin Batygin and Michael Brown (you might recognize Brown as the man who killed Pluto) have now increased the mystery. In a recently published a study, they demonstrate that for KBOs that have orbits with a 250 AU, the orbits are actually physically aligned.To explain this unexpected alignment which Batygin and Brown calculate has only a 0.007% probability of having occurred by chance the authors ask an exciting question: could this be caused by the presence of an unseen, large, perturbing body further out in the solar system?Simulating a Ninth PlanetThe authors test this hypothesis by carrying out both analytical calculations and numerical N-body simulations designed to determine if the gravitational influence of a distant, planetary-mass companion can explain the behavior we observe from the large-orbit KBOs.Simulation of the effect of a distant planet (M = 10

  2. Searching for Circumprimary and Circumbinary Planets in Kepler Data

    Science.gov (United States)

    Haghighipour, Nader

    We propose to use the currently available data from the Kepler space telescope (specifically, variations in transit and eclipse timing) to detect planets in circumprimary and circumbinary orbits in binary star systems. The detection of planets in close binary stars during the past decade and the recent success of the Kepler space telescope in detecting planets in circumbinary orbits strongly suggest that planet formation in and around binary stars is robust and planets of variety of sizes may exist in dual-star systems. Given that approximately 60% of the main and pre-main sequence stars are in binaries, many of such planet-hosting dual-stars are expected to exist which naturally leads to several fundamental questions on the formation, characteristics, frequency, and habitability of their planets. However, the small number of the currently known planets in binary star systems (only 8) does not allow for arriving at statistically meaningful answers to these questions. The success of the Kepler space telescope in identifying more than 2300 planetary candidates (of which many may be in close dual-stars) and over 2100 eclipsing binaries has provided rich grounds for searching for planet-hosting binary stars and increasing the number of their planets. We propose to use the data from quarter 0 (Q0) to quarter 6 (Q6), to identify the signature(s) of planet(s) in and around binary stars by analyzing the variations in the times of planetary transit or the eclipses of the binary. We will use the transit timing variations of the +2300 planetary candidates for detecting stellar companions to their planet-hosting stars, and the eclipse timing variations of the +2100 binary star systems to detect circumbinary planets. We have developed a powerful algorithm dubbed as QATS that allows us to analyze eclipse and transit timing variations accurately and efficiently. To properly account for the frequency of planets in binary stars systems and comparing that with the frequency of

  3. Stars and Planets

    Science.gov (United States)

    Neta, Miguel

    2014-05-01

    'Estrelas e Planetas' (Stars and Planets) project was developed during the academic year 2009/2010 and was tested on three 3rd grade classes of one school in Quarteira, Portugal. The aim was to encourage the learning of science and the natural and physical phenomena through the construction and manipulation of materials that promote these themes - in this case astronomy. Throughout the project the students built a small book containing three themes of astronomy: differences between stars and planets, the solar system and the phases of the Moon. To each topic was devoted two sessions of about an hour each: the first to teach the theoretical aspects of the theme and the second session to assembly two pages of the book. All materials used (for theoretical sessions and for the construction of the book) and videos of the finished book are available for free use in www.miguelneta.pt/estrelaseplanetas. So far there is only a Portuguese version but soon will be published in English as well. This project won the Excellency Prize 2011 of Casa das Ciências, a portuguese site for teachers supported by the Calouste Gulbenkian Fundation (www.casadasciencias.org).

  4. Planet X - Fact or fiction?

    Science.gov (United States)

    Anderson, John

    1988-01-01

    The search for a possible tenth planet in our solar system is examined. The history of the discoveries of Uranus, Neptune, and Pluto are reviewed. Searches of the sky with telescopes and theoretical studies of the gravitational influences on the orbits of known objects in the solar system are discussed. Information obtained during the Pioneer 10 and 11 missions which could suggest the presence of an undiscovered planet and computer simulations of the possible orbit of a tenth planet are presented.

  5. Planet X - ract or fiction

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, J.

    1988-08-01

    The search for a possible tenth planet in our solar system is examined. The history of the discoveries of Uranus, Neptune, and Pluto are reviewed. Searches of the sky with telescopes and theoretical studies of the gravitational influences on the orbits of known objects in the solar system are discussed. Information obtained during the Pioneer 10 and 11 missions which could suggest the presence of an undiscovered planet and computer simulations of the possible orbit of a tenth planet are presented.

  6. The hunt for Planet X

    Energy Technology Data Exchange (ETDEWEB)

    Croswell, Ken

    1990-12-29

    This article examines the hypothesis that an, as yet unobserved, planet, beyond the orbit of Pluto is responsible for peculiarities in the orbits of Uranus and Neptune. A brief overview of the discovery and observation of the outer planets is offered. The evidence for and against the proposition is noted, and the work of two present day scientists, is mentioned both of whom agree with the idea, and are searching for optical proof of the planet's existence. U.K.

  7. Planet X - Fact or fiction?

    Science.gov (United States)

    Anderson, John

    1988-08-01

    The search for a possible tenth planet in our solar system is examined. The history of the discoveries of Uranus, Neptune, and Pluto are reviewed. Searches of the sky with telescopes and theoretical studies of the gravitational influences on the orbits of known objects in the solar system are discussed. Information obtained during the Pioneer 10 and 11 missions which could suggest the presence of an undiscovered planet and computer simulations of the possible orbit of a tenth planet are presented.

  8. Professor: The Animal Planet Optimization

    OpenAIRE

    Satish Gajawada

    2014-01-01

    This paper is dedicated to everyone who is interested in making this planet a better place to live. In the past, researchers have explored behavior of several animals separately. But there is scope to explore in the direction where various artificial animals together solve the optimization problem. In this paper, Satish Gajawada proposed The AnimalPlanet Optimization. The concept of this paper is to imitate all the animals on this planet. The idea is to solve the optimization problem where al...

  9. Analysis of Science Attitudes for K2 Planet Hunter Mission

    Science.gov (United States)

    2015-03-01

    stated was “designed to detect transits of Earth-size planets in the ‘habitable zone’ orbiting 9<mv᝿, F through M type dwarf stars… in the...Flaring stars • Accreting stars and interacting binaries • Galaxies and supernovae • Microlenses C. THESIS OBJECTIVE AND SCOPE This thesis focuses on...forces so that it assumes a hydrostatic equilibrium (nearly round) shape, and (c) has cleared the neighbourhood around its orbit. (2) A “ dwarf planet

  10. What is a Planet?-Categorizing Objects

    Science.gov (United States)

    Lebofsky, Larry A.

    2009-05-01

    Observing, communicating, comparing, organizing, relating, and inferring are fundamental to scientific thinking processes. Teaching this way, rather than just teaching "the facts,” is also important for developing the critical thinking skills of our future generations of a scientifically literate society. Since the IAU started its discussions on a definition of a planet in 2005, I have been presenting a hands-on activity called "What is a Planet?” at the annual meeting of the DPS. This activity has been designed for short (20 minute) to long (two hour) presentations depending on the venue and the audience. This has been presented to elementary-grade students, middle school students, K-12 teachers, and scientists and educators. Depending on the amount of time available, I show students how people, as well as scientists group or categorize things such as plants and animals, cats and dog, etc. The students are then broken up into groups. Science is usually done by teams of scientists working together, not as individuals working alone. I assess their prior knowledge (how many planets, their names, their properties, etc.). They also do a hands-on group activity where they group/categorize ten spheres by their properties (size, color, etc.). Finally we discuss the process by which the IAU came up with a definition of a planet. I then discuss with them why some scientists, including myself, do not agree with this definition: as with the spheres, there may be more than one "right” answer. There are many ways to look at the properties of objects in the Solar System and group them into planets and other designations. This is the way that science should be done, to look at all of the properties of an object and categorize them in a meaningful way. There may be more than one right answer.

  11. Microlensing Discovery of an Earth-Mass Planet

    Science.gov (United States)

    Kohler, Susanna

    2017-04-01

    What do we know about planet formation around stars that are so light that they cant fuse hydrogen in their cores? The new discovery of an Earth-mass planet orbiting what is likely a brown dwarf may help us better understand this process.Planets Around Brown Dwarfs?Comparison of the sizes of the Sun, a low-mass star, a brown dwarf, Jupiter, and Earth. [NASA/JPL-Caltech/UCB]Planets are thought to form from the material inprotoplanetary disks around their stellar hosts. But the lowest-mass end of the stellar spectrum brown dwarfs, substellar objects so light that they straddle the boundary between planet and star will have correspondingly light disks. Do brown dwarfs disks typically have enough mass to form Earth-mass planets?To answer this question, scientists have searched for planets around brown dwarfs with marginal success. Thus far, only four such planets have been found and these systems may not be typical, since they were discovered via direct imaging. To build a more representative sample, wed like to discover exoplanets around brown dwarfs via a method that doesnt rely on imaging the faint light of the system.A diagram of how planets are detected via gravitational microlensing. The detectable planet is in orbit around the foreground lens star. [NASA]Lensed Light as a GiveawayConveniently, such a method exists and its recently been used to make a major discovery! The planet OGLE-2016-BLG-1195Lb was detected as a result of a gravitational microlensing event that was observed both from the ground and from space.The discovery of a planet via microlensing occurs when the light of a distant source star is magnified by a passing foreground star hosting a planet. The light curve of the source shows a distinctive magnification signature as a result of the gravitational lensing from the foreground star, and the gravitational field of the lensing stars planet can add its own detectable blip to the curve.OGLE-2016-BLG-1195LbThe magnification curve of OGLE-2016-BLG-1195

  12. Identifying Exoplanets with Deep Learning: A Five-planet Resonant Chain around Kepler-80 and an Eighth Planet around Kepler-90

    Science.gov (United States)

    Shallue, Christopher J.; Vanderburg, Andrew

    2018-02-01

    NASA’s Kepler Space Telescope was designed to determine the frequency of Earth-sized planets orbiting Sun-like stars, but these planets are on the very edge of the mission’s detection sensitivity. Accurately determining the occurrence rate of these planets will require automatically and accurately assessing the likelihood that individual candidates are indeed planets, even at low signal-to-noise ratios. We present a method for classifying potential planet signals using deep learning, a class of machine learning algorithms that have recently become state-of-the-art in a wide variety of tasks. We train a deep convolutional neural network to predict whether a given signal is a transiting exoplanet or a false positive caused by astrophysical or instrumental phenomena. Our model is highly effective at ranking individual candidates by the likelihood that they are indeed planets: 98.8% of the time it ranks plausible planet signals higher than false-positive signals in our test set. We apply our model to a new set of candidate signals that we identified in a search of known Kepler multi-planet systems. We statistically validate two new planets that are identified with high confidence by our model. One of these planets is part of a five-planet resonant chain around Kepler-80, with an orbital period closely matching the prediction by three-body Laplace relations. The other planet orbits Kepler-90, a star that was previously known to host seven transiting planets. Our discovery of an eighth planet brings Kepler-90 into a tie with our Sun as the star known to host the most planets.

  13. Tectonic evolution of the terrestrial planets.

    Science.gov (United States)

    Head, J W; Solomon, S C

    1981-07-03

    The style and evolution of tectonics on the terrestrial planets differ substantially. The style is related to the thickness of the lithosphere and to whether the lithosphere is divided into distinct, mobile plates that can be recycled into the mantle, as on Earth, or is a single spherical shell, as on the moon, Mars, and Mercury. The evolution of a planetary lithosphere and the development of plate tectonics appear to be influenced by several factors, including planetary size, chemistry, and external and internal heat sources. Vertical tectonic movement due to lithospheric loading or uplift is similar on all of the terrestrial planets and is controlled by the local thickness and rheology of the lithosphere. The surface of Venus, although known only at low resolution, displays features both similar to those on Earth (mountain belts, high plateaus) and similar to those on the smaller planets (possible impact basins). Improved understanding of the tectonic evolution of Venus will permit an evaluation of the relative roles of planetary size and chemistry in determining evolutionary style.

  14. Search for planet X

    Science.gov (United States)

    Harrington, Robert S.

    1991-01-01

    The observation of the region of the sky in which it is believed Planet X should now be, based on perturbations observed in the motions of Uranus and Neptune, was determined, and there was no reason to update that determination. A limited area of that region was photographed, and that will be continued. A given area is photographed with the twin 20 cm astrograph in New Zealand on two successive nights near the time that area is in opposition, and these plates are blinked in Washington to identify anything that has moved. The predicted region is in the south, which requires observations from a southern station, and it is in opposition in the April to June period, which means observations have not yet started for the year. Blinking will be done as soon as the plates are received in Washington.

  15. A sub-Mercury-sized exoplanet

    OpenAIRE

    Barclay, Thomas; Ciardi, David; Howard, Andrew W.

    2013-01-01

    Since the discovery of the first exoplanets, it has been known that other planetary systems can look quite unlike our own. Until fairly recently, we have been able to probe only the upper range of the planet size distribution, and, since last year, to detect planets that are the size of Earth or somewhat smaller. Hitherto, no planets have been found that are smaller than those we see in the Solar System. Here we report a planet significantly smaller than Mercury. This tiny planet is the inner...

  16. THREE PLANETS ORBITING WOLF 1061

    Energy Technology Data Exchange (ETDEWEB)

    Wright, D. J.; Wittenmyer, R. A.; Tinney, C. G.; Bentley, J. S.; Zhao, Jinglin, E-mail: duncan.wright@unsw.edu.au [Department of Astronomy and Australian Centre for Astrobiology, School of Physics, University of New South Wales, NSW 2052 (Australia)

    2016-02-01

    We use archival HARPS spectra to detect three planets orbiting the M3 dwarf Wolf 1061 (GJ 628). We detect a 1.36 M{sub ⊕} minimum-mass planet with an orbital period P = 4.888 days (Wolf 1061b), a 4.25 M{sub ⊕} minimum-mass planet with orbital period P = 17.867 days (Wolf 1061c), and a likely 5.21 M{sub ⊕} minimum-mass planet with orbital period P = 67.274 days (Wolf 1061d). All of the planets are of sufficiently low mass that they may be rocky in nature. The 17.867 day planet falls within the habitable zone for Wolf 1061 and the 67.274 day planet falls just outside the outer boundary of the habitable zone. There are no signs of activity observed in the bisector spans, cross-correlation FWHMs, calcium H and K indices, NaD indices, or Hα indices near the planetary periods. We use custom methods to generate a cross-correlation template tailored to the star. The resulting velocities do not suffer the strong annual variation observed in the HARPS DRS velocities. This differential technique should deliver better exploitation of the archival HARPS data for the detection of planets at extremely low amplitudes.

  17. Chemical kinetics on extrasolar planets.

    Science.gov (United States)

    Moses, Julianne I

    2014-04-28

    Chemical kinetics plays an important role in controlling the atmospheric composition of all planetary atmospheres, including those of extrasolar planets. For the hottest exoplanets, the composition can closely follow thermochemical-equilibrium predictions, at least in the visible and infrared photosphere at dayside (eclipse) conditions. However, for atmospheric temperatures approximately planets.

  18. Kepler constraints on planets near hot Jupiters.

    Science.gov (United States)

    Steffen, Jason H; Ragozzine, Darin; Fabrycky, Daniel C; Carter, Joshua A; Ford, Eric B; Holman, Matthew J; Rowe, Jason F; Welsh, William F; Borucki, William J; Boss, Alan P; Ciardi, David R; Quinn, Samuel N

    2012-05-22

    We present the results of a search for planetary companions orbiting near hot Jupiter planet candidates (Jupiter-size candidates with orbital periods near 3 d) identified in the Kepler data through its sixth quarter of science operations. Special emphasis is given to companions between the 21 interior and exterior mean-motion resonances. A photometric transit search excludes companions with sizes ranging from roughly two-thirds to five times the size of the Earth, depending upon the noise properties of the target star. A search for dynamically induced deviations from a constant period (transit timing variations) also shows no significant signals. In contrast, comparison studies of warm Jupiters (with slightly larger orbits) and hot Neptune-size candidates do exhibit signatures of additional companions with these same tests. These differences between hot Jupiters and other planetary systems denote a distinctly different formation or dynamical history.

  19. Kepler constraints on planets near hot Jupiters

    Energy Technology Data Exchange (ETDEWEB)

    Steffen, Jason H.; /Fermilab; Ragozzine, Darin; /Harvard-Smithsonian Ctr. Astrophys.; Fabrycky, Daniel C.; /UC, Santa Cruz, Astron. Astrophys.; Carter, Joshua A.; /Harvard-Smithsonian Ctr. Astrophys.; Ford, Eric B.; /Florida U.; Holman, Matthew J.; /Harvard-Smithsonian Ctr. Astrophys.; Rowe, Jason F.; /NASA, Ames; Welsh, William F.; /San Diego State U., Astron. Dept.; Borucki, William J.; /NASA, Ames; Boss, Alan P.; /Carnegie Inst., Wash., D.C., DTM; Ciardi, David R.; /Caltech /Harvard-Smithsonian Ctr. Astrophys.

    2012-05-01

    We present the results of a search for planetary companions orbiting near hot Jupiter planet candidates (Jupiter-size candidates with orbital periods near 3 d) identified in the Kepler data through its sixth quarter of science operations. Special emphasis is given to companions between the 2:1 interior and exterior mean-motion resonances. A photometric transit search excludes companions with sizes ranging from roughly two-thirds to five times the size of the Earth, depending upon the noise properties of the target star. A search for dynamically induced deviations from a constant period (transit timing variations) also shows no significant signals. In contrast, comparison studies of warm Jupiters (with slightly larger orbits) and hot Neptune-size candidates do exhibit signatures of additional companions with these same tests. These differences between hot Jupiters and other planetary systems denote a distinctly different formation or dynamical history.

  20. Origins and Destinations: Tracking Planet Composition through Planet Formation Simulations

    Science.gov (United States)

    Chance, Quadry

    2017-10-01

    There are now several thousand confirmed exoplanets, a number which far exceeds our resources to study them all in detail. In particular, planets around M dwarfs provide the best opportunity for in-depth study of their atmospheres by telescopes in the near future. The question of which M dwarf planets most merit follow-up resources is a pressing one, given that NASA’s TESS mission will soon find hundreds of such planets orbiting stars bright enough for both ground and spaced-based observation.Our work aims to predict the approximate composition of planets around these stars through n-body simulations of the last stage of planet formation. With a variety of initial disk conditions, we investigate how the relative abundances of both refractory and volatile compounds in the primordial planetesimals are mapped to the final planet outcomes. These predictions will serve to provide a basis for making an educated guess about (a) which planets to observe with precious resources like JWST and (b) how to identify them based on dynamical clues.

  1. Violent Adolescent Planet Caught Infrared Handed

    Science.gov (United States)

    Trang, D.; Gaidos, E.

    2010-01-01

    The prevailing view of planet formation depicts accumulation of progressively larger objects, culminating in accretionary impacts between Moon- to Mars-sized protoplanets. Cosmochemists have found evidence in chondritic meteorites for such violent events, and the Moon is thought to have involved a huge impact between a Mars-sized object and the still-growing proto-Earth. Now we may have evidence for a large impact during planet formation around another star. Carey Lisse (Applied Physics Lab of the Johns Hopkins University, Baltimore) and colleagues from the Space Telescope Science Institute (Baltimore), the University of Cambridge (UK), the Open University (Milton Keyes, UK), the University of Georgia (Athens, GA), Jet Propulsion Lab (Pasadena, CA), and the University of Rochester (New York) analyzed infrared spectra obtained by the Spitzer Space Telescope. They found a prominent peak in the spectrum at 9.3 micrometers, and two smaller ones at slightly lower and higher wavelengths. These peaks are consistent with the presence of SiO gas, a product expected to be produced by a highly energetic impact. The spectral measurements also allowed Lisse and his colleagues to estimate the size of the dust and they found that there is an abundance of micrometer-sized dust grains. This argues for a fresh source of fine material during the past 0.1 million years. That source may have been an impact between two protoplanets surrounding this young star.

  2. Double Planet Meets Triple Star

    Science.gov (United States)

    2002-08-01

    Photos 21b-c/02 . These images were made during the final adjustments of the NACO instrument and in anticipation of the upcoming science verification observations. All frames are now publicly available from the NACO data webpage on the ESO site. The NACO image shown was obtained in infrared light (in the K-band at wavelength 2.2 µm) on July 20, 2002, some 45 min before Pluto's shadow passed north of Paranal ( Photo 21a/02) . The orientation is such that North is up, and East is left. The small sky field measures about 7 x 7 arcsec 2. The pixel size is 0.027 arcsec, and the achieved image sharpness corresponds to the theoretical limit (the diffraction limit) with a telescope of this size and at this wavelength (0.07 arcsec). The object at the centre is the star P126 A of K-magnitude 9.5 (see also Photo 21c/02 where the objects are identified), while the brighter object at the right is the companion star P126 B , 2.25 arcsec away. As P126 B is very red (of stellar type M), it appears brighter than P126 A at this infrared wavelength - the opposite is true in visible light. The intensity of the left part of the image has been multiplied by a factor of approximately 35 in order to better display Pluto and its moon Charon , located some 0.5 arcsec to the lower left (SE) of the planet. Note also the faint star "P126 C" , at this moment very close to Pluto; it is probably a (physical) member of the P126 system. A closer inspection of the original image shows that the disk of Pluto (with a diameter of 0.107 arscec and covering 16 NACO pixels) is (barely) resolved. Many images were taken by NACO prior to the occultation. They will allow to retrace the precise motion of Pluto relative to P126 A, thereby improving the mapping of the motion of Pluto's shadow on the ground, cf. Photo 21a/02 . This is important in order to apply the correct geometrical circumstances for the interpretation of the photometric observations. A first evaluation of the NACO data indicates that the Paranal

  3. Theories of the origin and evolution of the giant planets

    Science.gov (United States)

    Pollack, J. B.; Bodenheimer, P.

    1989-01-01

    Following the accretion of solids and gases in the solar nebula, the giant planets contracted to their present sizes over the age of the solar system. It is presently hypothesized that this contraction was rapid, but not hydrodynamic; at a later stage, a nebular disk out of which the regular satellites formed may have been spun out of the outer envelope of the contracting giant planets due to a combination of total angular momentum conservation and the outward transfer of specific angular momentum in the envelope. If these hypotheses are true, the composition of the irregular satellites directly reflects the composition of planetesimals from which the giant planets formed, while the composition of the regular satellites is indicative of the composition of the less volatile components of the outer envelopes of the giant planets.

  4. An Earth-mass planet orbiting α Centauri B.

    Science.gov (United States)

    Dumusque, Xavier; Pepe, Francesco; Lovis, Christophe; Ségransan, Damien; Sahlmann, Johannes; Benz, Willy; Bouchy, François; Mayor, Michel; Queloz, Didier; Santos, Nuno; Udry, Stéphane

    2012-11-08

    Exoplanets down to the size of Earth have been found, but not in the habitable zone--that is, at a distance from the parent star at which water, if present, would be liquid. There are planets in the habitable zone of stars cooler than our Sun, but for reasons such as tidal locking and strong stellar activity, they are unlikely to harbour water-carbon life as we know it. The detection of a habitable Earth-mass planet orbiting a star similar to our Sun is extremely difficult, because such a signal is overwhelmed by stellar perturbations. Here we report the detection of an Earth-mass planet orbiting our neighbour star α Centauri B, a member of the closest stellar system to the Sun. The planet has an orbital period of 3.236 days and is about 0.04 astronomical units from the star (one astronomical unit is the Earth-Sun distance).

  5. The role of disc self-gravity in circumbinary planet systems - II. Planet evolution

    Science.gov (United States)

    Mutter, Matthew M.; Pierens, Arnaud; Nelson, Richard P.

    2017-08-01

    We present the results of hydrodynamic simulations examining migration and growth of planets embedded in self-gravitating circumbinary discs. The binary star parameters are chosen to mimic those of the Kepler-16, -34 and -35 systems; the aim of this study is to examine the role of disc mass in determining the stopping locations of migrating planets at the edge of the cavity created by the central binary. Disc self-gravity can cause significant shrinkage of the cavity for disc masses in excess of 5-10 × the minimum mass solar nebula model. Planets forming early in the disc lifetime can migrate through the disc and stall at locations closer to the central star than is normally the case for lower mass discs, resulting in closer agreement between simulated and observed orbital architecture. The presence of a planet orbiting in the cavity of a massive disc can prevent the cavity size from expanding to the size of a lower mass disc. As the disc mass reduces over long time-scales, this indicates that circumbinary planet systems retain memory of their initial conditions. Our simulations produce planetary orbits in good agreement with Keper-16b without the need for self-gravity; Kepler-34 analogue systems produce wide and highly eccentric cavities, and self-gravity improves the agreement between simulations and data. Kepler-35b is more difficult to explain in detail due to its relatively low mass, which results in the simulated stopping location being at a larger radius than that observed.

  6. Planet-Planet Scattering and White Dwarf Pollution

    Science.gov (United States)

    Joasil, Arielle; Payne, Matthew John; Veras, Dimitri

    2017-01-01

    About one-quarter to one-half of white dwarfs are observed to have polluted atmospheres. White dwarfs (WD) are expected to be chemically stratified, with heavy elements rapidly sinking. The frequent observation of heavy element pollution in WD atmospheres indicates that there must be a copious and frequent supply of rocky material from remnant planetary systems acting as a pollutant. Recently, the white dwarf WD 1145+017 has been observed to have been transited by a rocky body apparently in the process of disintegrating (Vanderburg et al. 2015).Post-main sequence expansion may render the planetary system unstable (Veras 2016). Planets orbiting the white dwarf may perturb and scatter one another. If this scattering happens, any moons can be scattered about the system. As such, one possible source of the material polluting WDs is destabilized exomoons (Payne et al. 2016a, 2016b). Moons offer a plausible source of pollution due to their large total mass (in the Solar system), and their generally rocky composition that matches that found in the atmospheric pollution of WDs. During a planet-planet scattering event, the probability that a moon will be ejected from its parent planet is a function of the velocity of the perturbing planet and the distance between the perturbed moon and the perturbing planet (as well as the initial orbit of the moon). We review the results of Payne et al. (2016a, 2016b) and present new results illustrating the probability of moon ejection as a function of these key parameters. We demonstrate the utility of these results for (a) the pollution and WDs, and for (b) general planet-planet scattering scenarios around main-sequence stars.

  7. Extreme Adaptive Optics Planet Imager: XAOPI

    Energy Technology Data Exchange (ETDEWEB)

    Macintosh, B A; Graham, J; Poyneer, L; Sommargren, G; Wilhelmsen, J; Gavel, D; Jones, S; Kalas, P; Lloyd, J; Makidon, R; Olivier, S; Palmer, D; Patience, J; Perrin, M; Severson, S; Sheinis, A; Sivaramakrishnan, A; Troy, M; Wallace, K

    2003-09-17

    Ground based adaptive optics is a potentially powerful technique for direct imaging detection of extrasolar planets. Turbulence in the Earth's atmosphere imposes some fundamental limits, but the large size of ground-based telescopes compared to spacecraft can work to mitigate this. We are carrying out a design study for a dedicated ultra-high-contrast system, the eXtreme Adaptive Optics Planet Imager (XAOPI), which could be deployed on an 8-10m telescope in 2007. With a 4096-actuator MEMS deformable mirror it should achieve Strehl >0.9 in the near-IR. Using an innovative spatially filtered wavefront sensor, the system will be optimized to control scattered light over a large radius and suppress artifacts caused by static errors. We predict that it will achieve contrast levels of 10{sup 7}-10{sup 8} at angular separations of 0.2-0.8 inches around a large sample of stars (R<7-10), sufficient to detect Jupiter-like planets through their near-IR emission over a wide range of ages and masses. We are constructing a high-contrast AO testbed to verify key concepts of our system, and present preliminary results here, showing an RMS wavefront error of <1.3 nm with a flat mirror.

  8. The California-Kepler Survey. IV. Metal-rich Stars Host a Greater Diversity of Planets

    Science.gov (United States)

    Petigura, Erik A.; Marcy, Geoffrey W.; Winn, Joshua N.; Weiss, Lauren M.; Fulton, Benjamin J.; Howard, Andrew W.; Sinukoff, Evan; Isaacson, Howard; Morton, Timothy D.; Johnson, John Asher

    2018-02-01

    Probing the connection between a star’s metallicity and the presence and properties of any associated planets offers an observational link between conditions during the epoch of planet formation and mature planetary systems. We explore this connection by analyzing the metallicities of Kepler target stars and the subset of stars found to host transiting planets. After correcting for survey incompleteness, we measure planet occurrence: the number of planets per 100 stars with a given metallicity M. Planet occurrence correlates with metallicity for some, but not all, planet sizes and orbital periods. For warm super-Earths having P = 10–100 days and {R}P = 1.0–1.7 {R}\\oplus , planet occurrence is nearly constant over metallicities spanning ‑0.4 to +0.4 dex. We find 20 warm super-Earths per 100 stars, regardless of metallicity. In contrast, the occurrence of warm sub-Neptunes ({R}P = 1.7–4.0 {R}\\oplus ) doubles over that same metallicity interval, from 20 to 40 planets per 100 stars. We model the distribution of planets as {df}\\propto {10}β M{dM}, where β characterizes the strength of any metallicity correlation. This correlation steepens with decreasing orbital period and increasing planet size. For warm super-Earths β = -{0.3}-0.2+0.2, while for hot Jupiters β = +{3.4}-0.8+0.9. High metallicities in protoplanetary disks may increase the mass of the largest rocky cores or the speed at which they are assembled, enhancing the production of planets larger than 1.7 {R}\\oplus . The association between high metallicity and short-period planets may reflect disk density profiles that facilitate the inward migration of solids or higher rates of planet–planet scattering.

  9. Formation of Extrasolar Giant Planets by Core Nucleated Accretion

    Science.gov (United States)

    Bodenheimer, Peter

    Central objectives: Improving our understanding of extra-solar gas giant planet formation through the Core-Nucleated Accretion model, based on constraints derived from extrasolar planet observations. More specifically, we will determine: (1) the physical conditions in a protoplanetary disk, at various distances from the star, that may lead to the formation of gas giant planets; (2) the effects of planetary migration, due to resonant torques, on realistic planet formation models, when disk evolution is taken into account; (3) luminosities, surface temperatures, and other observable properties of giant planets formed through core-nucleated accretion, which will help in the characterization of young planet candidates detected via imaging techniques. Methods and techniques: We will pursue these objectives mainly by means of numerical modeling. A number of state-of-the-art codes will be employed to model in detail different processes at various stages of the planet's growth. (1) A multi-zone accretion code will be used to model accretion of planetesimals onto the solid core. This approach will allow us to account for the evolution of the size distribution of the planetesimals, the variations of their velocity distribution relative to the planet's core, the orbital spacing of potential competing cores, and a time variable rate of accretion of small planetesimals with a range of sizes as well as of stochastic impacts of larger bodies. All these effects will provide a more accurate determination of the time scales for the growth of a giant planet's solid core. (2) A planet formation code that includes a large number of physical effects, calculated in a detailed manner, will be used to model the planet evolution until gas accretion ends. The code computes the interaction of the planetesimals with the protoplanet's envelope and determines whether the planetesimals reach the core or are dissolved in the envelope. The calculation of the thermal structure of the envelope takes

  10. Kepler Planet-Detection Mission: Introduction and First Results

    Energy Technology Data Exchange (ETDEWEB)

    Borucki, William J.; /NASA, Ames; Koch, David; /NASA, Ames; Basri, Gibor; /UC, Berkeley; Batalha, Natalie; /San Jose State U.; Brown, Timothy; /Las Cumbres Observ.; Caldwell, Douglas; /SETI Inst., Mtn. View; Caldwell, John; /York U., Canada; Christensen-Dalsgaard, Jorgen; /Aarhus U.; Cochran, William D.; /Texas U.; DeVore, Edna; /SETI Inst., Mtn. View; Dunham, Edward W.; /Lowell Observ. /Harvard-Smithsonian Ctr. Astrophys.

    2010-01-01

    The Kepler mission was designed to determine the frequency of Earth-sized planets in and near the habitable zone of Sun-like stars. The habitable zone is the region where planetary temperatures are suitable for water to exist on a planet's surface. During the first 6 weeks of observations, Kepler monitored 156,000 stars, and five new exoplanets with sizes between 0.37 and 1.6 Jupiter radii and orbital periods from 3.2 to 4.9 days were discovered. The density of the Neptune-sized Kepler-4b is similar to that of Neptune and GJ 436b, even though the irradiation level is 800,000 times higher. Kepler-7b is one of the lowest-density planets ({approx}0.17 gram per cubic centimeter) yet detected. Kepler-5b, -6b, and -8b confirm the existence of planets with densities lower than those predicted for gas giant planets.

  11. Physical properties of the planet Mercury

    Science.gov (United States)

    Clark, Pamela E.

    1988-01-01

    The global physical properties of Mercury are summarized with attention given to its figure and orbital parameters. The combination of properties suggests that Mercury has an extensive iron-rich core, possibly with a still-functioning dynamo, which is 42 percent of the interior by volume. Mercury's three major axes are comparable in size, indicating that the planet is a triaxial ellipsoid rather than an oblate spheroid. In terms of the domination of its surface by an intermediate plains terrane, it is more Venus- or Mars-like; however, due to the presence of a large metallic magnetic core, its interior may be more earth-like.

  12. Armenian Names of the Planets

    Science.gov (United States)

    Harutyunian, Haik A.

    2007-08-01

    Striking similarities between the Armenian names of visible to the naked eye planets and their ancient Greek names used before 6 - 5 centuries BC are presented. Mercury, for instance, was called Stilbon in Greece which means “the Gleaming” and coincides with Armenian Paylatsou. One of the names of Venus was Phosphoros and in Armenia it is called Lusaber - both of these terms meaning the “Bringer of Light”. Ancient Greeks named the fourth planet Pyroeis meaning “fiery”. The Armenian name of this planet Hrat consists of the word “hur” meaning fire and a suffix “at”. Jupiter's and Saturn's ancient names are considered as well. Moreover, the term planet has its Armenian version being in the use more than 2500 years.

  13. Dictionary of Minor Planet Names

    CERN Document Server

    Schmadel, Lutz D

    2007-01-01

    Dictionary of Minor Planet Names, Fifth Edition, is the official reference for the field of the IAU, which serves as the internationally recognised authority for assigning designations to celestial bodies and any surface features on them. The accelerating rate of the discovery of minor planets has not only made a new edition of this established compendium necessary but has also significantly altered its scope: this thoroughly revised edition concentrates on the approximately 10,000 minor planets that carry a name. It provides authoritative information about the basis for all names of minor planets. In addition to being of practical value for identification purposes, this collection provides a most interesting historical insight into the work of those astronomers who over two centuries vested their affinities in a rich and colorful variety of ingenious names, from heavenly goddesses to more prosaic constructions. The fifth edition serves as the primary reference, with plans for complementary booklets with newl...

  14. Planets, stars and stellar systems

    CERN Document Server

    Bond, Howard; McLean, Ian; Barstow, Martin; Gilmore, Gerard; Keel, William; French, Linda

    2013-01-01

    This is volume 3 of Planets, Stars and Stellar Systems, a six-volume compendium of modern astronomical research covering subjects of key interest to the main fields of contemporary astronomy. This volume on “Solar and Stellar Planetary Systems” edited by Linda French and Paul Kalas presents accessible review chapters From Disks to Planets, Dynamical Evolution of Planetary Systems, The Terrestrial Planets, Gas and Ice Giant Interiors, Atmospheres of Jovian Planets, Planetary Magnetospheres, Planetary Rings, An Overview of the Asteroids and Meteorites, Dusty Planetary Systems and Exoplanet Detection Methods. All chapters of the handbook were written by practicing professionals. They include sufficient background material and references to the current literature to allow readers to learn enough about a specialty within astronomy, astrophysics and cosmology to get started on their own practical research projects. In the spirit of the series Stars and Stellar Systems published by Chicago University Press in...

  15. HD 106315 and GJ 9827: Understanding the Formation and Evolution of Small Planets

    Science.gov (United States)

    Rodriguez, Joseph; Vanderburg, Andrew; Eastman, Jason; Zhou, George

    2018-01-01

    The success of ground-based transit and RV surveys, and the Kepler/K2 mission, has shifted the exoplanet field from pure discovery to a combination of discovery, demographic analysis, and atmospheres, with the goal of understanding how planets form and evolve. The discovery of super Earth and sub-Neptune sized planets, planets with no analogue in our own solar system, span a known transition from dense rock composition to thick gaseous atmospheres. Recently, we have discovered two exoplanet systems using data from the K2 mission which provide a great opportunity to understand how small planets form and evolve. HD 106315 hosts a sub-Neptune size planet on a 9.5 day period and a Neptune on a 21 day period. The host star’s brightness and higher than typical rotation period make HD 106315c one of the best small planets known to measure its spin-orbit alignment. This measurement may provide insight into its formation history as misaligned planets suggest a dynamical migration history. GJ 9827 hosts three super Earth planets that span the known rock to gas transition. From studying the atmospheres of these planets, we may better understand the mechanisms involved in creating the observed dichotomy at 1.6 Earth radii. I will discuss our recent results on these two systems and their importance to understanding the formation and evolution of small planets.

  16. THE HABITABILITY AND DETECTION OF EARTH-LIKE PLANETS ORBITING COOL WHITE DWARFS

    Energy Technology Data Exchange (ETDEWEB)

    Fossati, L.; Haswell, C. A.; Patel, M. R.; Busuttil, R. [Department of Physical Sciences, Open University, Walton Hall, Milton Keynes MK7 6AA (United Kingdom); Bagnulo, S. [Armagh Observatory, College Hill, Armagh BT61 9DG (United Kingdom); Kowalski, P. M. [GFZ German Research Centre for Geosciences, Telegrafenberg, D-14473 Potsdam (Germany); Shulyak, D. V. [Institute of Astrophysics, Georg-August-University, Friedrich-Hund-Platz 1, D-37077 Goettingen (Germany); Sterzik, M. F., E-mail: l.fossati@open.ac.uk, E-mail: C.A.Haswell@open.ac.uk, E-mail: M.R.Patel@open.ac.uk, E-mail: r.busuttil@open.ac.uk, E-mail: sba@arm.ac.uk, E-mail: kowalski@gfz-potsdam.de, E-mail: denis.shulyak@gmail.com, E-mail: msterzik@eso.org [European Southern Observatory, Casilla 19001, Santiago 19 (Chile)

    2012-09-20

    Since there are several ways planets can survive the giant phase of the host star, we examine the habitability and detection of planets orbiting white dwarfs. As a white dwarf cools from 6000 K to 4000 K, a planet orbiting at 0.01 AU would remain in the continuous habitable zone (CHZ) for {approx}8 Gyr. We show that photosynthetic processes can be sustained on such planets. The DNA-weighted UV radiation dose for an Earth-like planet in the CHZ is less than the maxima encountered on Earth, and hence non-magnetic white dwarfs are compatible with the persistence of complex life. Polarization due to a terrestrial planet in the CHZ of a cool white dwarf (CWD) is 10{sup 2} (10{sup 4}) times larger than it would be in the habitable zone of a typical M-dwarf (Sun-like star). Polarimetry is thus a viable way to detect close-in rocky planets around white dwarfs. Multi-band polarimetry would also allow us to reveal the presence of a planet atmosphere, providing a first characterization. Planets in the CHZ of a 0.6 M{sub Sun} white dwarf will be distorted by Roche geometry, and a Kepler-11d analog would overfill its Roche lobe. With current facilities a super-Earth-sized atmosphereless planet is detectable with polarimetry around the brightest known CWD. Planned future facilities render smaller planets detectable, in particular by increasing the instrumental sensitivity in the blue.

  17. A CONTINUUM OF PLANET FORMATION BETWEEN 1 AND 4 EARTH RADII

    Energy Technology Data Exchange (ETDEWEB)

    Schlaufman, Kevin C., E-mail: kschlauf@mit.edu [Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States)

    2015-02-01

    It has long been known that stars with high metallicity are more likely to host giant planets than stars with low metallicity. Yet the connection between host star metallicity and the properties of small planets is only just beginning to be investigated. It has recently been argued that the metallicity distribution of stars with exoplanet candidates identified by Kepler provides evidence for three distinct clusters of exoplanets, distinguished by planet radius boundaries at 1.7 R{sub ⨁} and 3.9 R{sub ⨁}. This would suggest that there are three distinct planet formation pathways for super-Earths, mini-Neptunes, and giant planets. However, as I show through three independent analyses, there is actually no evidence for the proposed radius boundary at 1.7 R{sub ⨁}. On the other hand, a more rigorous calculation demonstrates that a single, continuous relationship between planet radius and metallicity is a better fit to the data. The planet radius and metallicity data therefore provides no evidence for distinct categories of small planets. This suggests that the planet formation process in a typical protoplanetary disk produces a continuum of planet sizes between 1 R{sub ⨁} and 4 R{sub ⨁}. As a result, the currently available planet radius and metallicity data for solar-metallicity F and G stars give no reason to expect that the amount of solid material in a protoplanetary disk determines whether super-Earths or mini-Neptunes are formed.

  18. Evolution of Earth Like Planets

    Science.gov (United States)

    Monroy-Rodríguez, M. A.; Vega, K. M.

    2017-07-01

    In order to study and explain the evolution of our own planet we have done a review of works related to the evolution of Earth-like planets. From the stage of proto-planet to the loss of its atmosphere. The planetary formation from the gas and dust of the proto-planetary disk, considering the accretion by the process of migration, implies that the material on the proto-planet is very mixed. The newborn planet is hot and compact, it begins its process of stratification by gravity separation forming a super dense nucleus, an intermediate layer of convective mantle and an upper mantle that is less dense, with material that emerges from zones at very high pressure The surface with low pressure, in this process the planet expands and cools. This process also releases gas to the surface, forming the atmosphere, with the gas gravitationally bounded. The most important thing for the life of the planet is the layer of convective mantle, which produces the magnetic field, when it stops the magnetic field disappears, as well as the rings of van allen and the solar wind evaporates the atmosphere, accelerating the evolution and cooling of the planet. In a natural cycle of cataclysms and mass extinctions, the solar system crosses the galactic disk every 30 million years or so, the increase in the meteorite fall triggers the volcanic activity and the increase in the release of CO2 into the atmosphere reaching critical levels (4000 billion tons) leads us to an extinction by overheating that last 100 000 years, the time it takes CO2 to sediment to the ocean floor. Human activity will lead us to reach critical levels of CO2 in approximately 300 years.

  19. Fomalhaut's Debris Disk and Planet: Constraining the Mass of Formalhaut B from Disk Morphology

    Science.gov (United States)

    Chiang, E.; Kite, E.; Kalas, P.; Graham, J. R.; Clampin, M.

    2008-01-01

    -motion resonances with Fom b; these empty resonances are akin to the Kirkwood gaps opened by Jupiter. The belt contains at least 3M(sub Earth) of solids that are grinding down to dust, their velocity dispersions stirred so strongly by Fom b that collisions are destructive. Such a large mass in solids is consistent with Fom b having formed in situ.

  20. Kepler-62: a five-planet system with planets of 1.4 and 1.6 Earth radii in the habitable zone.

    Science.gov (United States)

    Borucki, William J; Agol, Eric; Fressin, Francois; Kaltenegger, Lisa; Rowe, Jason; Isaacson, Howard; Fischer, Debra; Batalha, Natalie; Lissauer, Jack J; Marcy, Geoffrey W; Fabrycky, Daniel; Désert, Jean-Michel; Bryson, Stephen T; Barclay, Thomas; Bastien, Fabienne; Boss, Alan; Brugamyer, Erik; Buchhave, Lars A; Burke, Chris; Caldwell, Douglas A; Carter, Josh; Charbonneau, David; Crepp, Justin R; Christensen-Dalsgaard, Jørgen; Christiansen, Jessie L; Ciardi, David; Cochran, William D; DeVore, Edna; Doyle, Laurance; Dupree, Andrea K; Endl, Michael; Everett, Mark E; Ford, Eric B; Fortney, Jonathan; Gautier, Thomas N; Geary, John C; Gould, Alan; Haas, Michael; Henze, Christopher; Howard, Andrew W; Howell, Steve B; Huber, Daniel; Jenkins, Jon M; Kjeldsen, Hans; Kolbl, Rea; Kolodziejczak, Jeffery; Latham, David W; Lee, Brian L; Lopez, Eric; Mullally, Fergal; Orosz, Jerome A; Prsa, Andrej; Quintana, Elisa V; Sanchis-Ojeda, Roberto; Sasselov, Dimitar; Seader, Shawn; Shporer, Avi; Steffen, Jason H; Still, Martin; Tenenbaum, Peter; Thompson, Susan E; Torres, Guillermo; Twicken, Joseph D; Welsh, William F; Winn, Joshua N

    2013-05-03

    We present the detection of five planets--Kepler-62b, c, d, e, and f--of size 1.31, 0.54, 1.95, 1.61 and 1.41 Earth radii (R⊕), orbiting a K2V star at periods of 5.7, 12.4, 18.2, 122.4, and 267.3 days, respectively. The outermost planets, Kepler-62e and -62f, are super-Earth-size (1.25 R⊕ planet radius ≤ 2.0 R⊕) planets in the habitable zone of their host star, respectively receiving 1.2 ± 0.2 times and 0.41 ± 0.05 times the solar flux at Earth's orbit. Theoretical models of Kepler-62e and -62f for a stellar age of ~7 billion years suggest that both planets could be solid, either with a rocky composition or composed of mostly solid water in their bulk.

  1. A sub-Mercury-sized exoplanet

    NARCIS (Netherlands)

    Barclay, T.; et al., [Unknown; Hekker, S.

    2013-01-01

    Since the discovery of the first exoplanets1, 2, it has been known that other planetary systems can look quite unlike our own3. Until fairly recently, we have been able to probe only the upper range of the planet size distribution4, 5, and, since last year, to detect planets that are the size of

  2. Gemini Planet Imager: Preliminary Design Report

    Energy Technology Data Exchange (ETDEWEB)

    Macintosh, B

    2007-05-10

    For the first time in history, direct and indirect detection techniques have enabled the exploration of the environments of nearby stars on scales comparable to the size of our solar system. Precision Doppler measurements have led to the discovery of the first extrasolar planets, while high-contrast imaging has revealed new classes of objects including dusty circumstellar debris disks and brown dwarfs. The ability to recover spectrophotometry for a handful of transiting exoplanets through secondary-eclipse measurements has allowed us to begin to study exoplanets as individual entities rather than points on a mass/semi-major-axis diagram and led to new models of planetary atmospheres and interiors, even though such measurements are only available at low SNR and for a handful of planets that are automatically those most modified by their parent star. These discoveries have galvanized public interest in science and technology and have led to profound new insights into the formation and evolution of planetary systems, and they have set the stage for the next steps--direct detection and characterization of extrasolar Jovian planets with instruments such as the Gemini Planet Imager (GPI). As discussed in Volume 1, the ability to directly detect Jovian planets opens up new regions of extrasolar planet phase space that in turn will inform our understanding of the processes through which these systems form, while near-IR spectra will advance our understanding of planetary physics. Studies of circumstellar debris disks using GPI's polarimetric mode will trace the presence of otherwise-invisible low-mass planets and measure the build-up and destruction of planetesimals. To accomplish the science mission of GPI will require a dedicated instrument capable of achieving contrast of 10{sup -7} or more. This is vastly better than that delivered by existing astronomical AO systems. Currently achievable contrast, about 10{sup -5} at separations of 1 arc second or larger, is

  3. A sub-Mercury-sized exoplanet.

    Science.gov (United States)

    Barclay, Thomas; Rowe, Jason F; Lissauer, Jack J; Huber, Daniel; Fressin, François; Howell, Steve B; Bryson, Stephen T; Chaplin, William J; Désert, Jean-Michel; Lopez, Eric D; Marcy, Geoffrey W; Mullally, Fergal; Ragozzine, Darin; Torres, Guillermo; Adams, Elisabeth R; Agol, Eric; Barrado, David; Basu, Sarbani; Bedding, Timothy R; Buchhave, Lars A; Charbonneau, David; Christiansen, Jessie L; Christensen-Dalsgaard, Jørgen; Ciardi, David; Cochran, William D; Dupree, Andrea K; Elsworth, Yvonne; Everett, Mark; Fischer, Debra A; Ford, Eric B; Fortney, Jonathan J; Geary, John C; Haas, Michael R; Handberg, Rasmus; Hekker, Saskia; Henze, Christopher E; Horch, Elliott; Howard, Andrew W; Hunter, Roger C; Isaacson, Howard; Jenkins, Jon M; Karoff, Christoffer; Kawaler, Steven D; Kjeldsen, Hans; Klaus, Todd C; Latham, David W; Li, Jie; Lillo-Box, Jorge; Lund, Mikkel N; Lundkvist, Mia; Metcalfe, Travis S; Miglio, Andrea; Morris, Robert L; Quintana, Elisa V; Stello, Dennis; Smith, Jeffrey C; Still, Martin; Thompson, Susan E

    2013-02-28

    Since the discovery of the first exoplanets, it has been known that other planetary systems can look quite unlike our own. Until fairly recently, we have been able to probe only the upper range of the planet size distribution, and, since last year, to detect planets that are the size of Earth or somewhat smaller. Hitherto, no planets have been found that are smaller than those we see in the Solar System. Here we report a planet significantly smaller than Mercury. This tiny planet is the innermost of three that orbit the Sun-like host star, which we have designated Kepler-37. Owing to its extremely small size, similar to that of the Moon, and highly irradiated surface, the planet, Kepler-37b, is probably rocky with no atmosphere or water, similar to Mercury.

  4. Homes for extraterrestrial life: extrasolar planets.

    Science.gov (United States)

    Latham, D W

    2001-12-01

    Astronomers are now discovering giant planets orbiting other stars like the sun by the dozens. But none of these appears to be a small rocky planet like the earth, and thus these planets are unlikely to be capable of supporting life as we know it. The recent discovery of a system of three planets is especially significant because it supports the speculation that planetary systems, as opposed to single orbiting planets, may be common. Our ability to detect extrasolar planets will continue to improve, and space missions now in development should be able to detect earth-like planets.

  5. Mars’ Growth Stunted by an Early Giant Planet Instability

    Science.gov (United States)

    Clement, Matthew; Kaib, Nathan A.; Raymond, Sean N.; Walsh, Kevin J.

    2017-10-01

    Many dynamical aspects of the solar system can be explained by the outer planets experiencing a period of orbital instability. Though often correlated with a perceived delayed spike in the lunar cratering record known as the Late Heavy Bombardment (LHB), recent work suggests that this event may have occurred during the epoch of terrestrial planet formation. Though current simulations of terrestrial accretion can reproduce many observed qualities of the solar system, replicating the small mass of Mars requires modification to standard planet formation models. Here we use direct numerical simulations to show that an early instability in the outer solar system regularly yields properly sized Mars analogues. In 80% of simulations, we produce a Mars of the appropriate mass. Our most successful outcomes occur when the terrestrial planets evolve 10 million years (Myr), and accrete several Mars sized embryos in the Mars forming region before the instability takes place. Mars is left behind as a stranded embryo, while the remainder of these bodies are either ejected from the system or scattered towards the inner solar system where they deliver water to Earth. An early giant planet instability can thus replicate both the inner and outer solar system in a single model.

  6. Characterization of extra-solar planets with direct-imaging techniques

    NARCIS (Netherlands)

    Tinetti, G.; Cash, W.; Glassman, T.; Keller, C.U.; Oakley, P.; Snik, F.; Stam, D.; Turnbull, M.

    2009-01-01

    In order to characterize the physical properties of an extra-solar planet one needs to detect planetary radiation, either visible (VIS) to near-infrared (NIR) reflected starlight or infrared (IR) thermal radiation. Both the reflected and thermal flux depend on the size of the planet, the distance

  7. Tectonic evolution of terrestrial planets

    Science.gov (United States)

    Head, J. W.; Solomon, S. C.

    1981-01-01

    The tectonic style of each terrestrial planet, referring to the thickness and division of its lithosphere, can be inferred from surface features and compared to models of planetary thermal history. Factors governing planetary tectonic evolution are planet diameter, chemistry, and external and internal heat sources, all of which determine how a planet generates and rids itself of heat. The earth is distinguished by its distinct, mobile plates, which are recycled into the mantle and show large-scale lateral movements, whereas the moon, Mars, and Mercury are single spherical shells, showing no evidence of destruction and renewal of the lithospheric plates over the latter 80% of their history. Their smaller volume to surface area results in a more rapid cooling, formation, and thickening of the lithosphere. Vertical tectonics, due to lithospheric loading, is controlled by the local thickness and rheology of the lithosphere. Further studies of Venus, which displays both the craterlike surface features of the one-plate planets, and the rifts and plateaus of earth, may indicate which factors are most important in controlling the tectonic evolution of terrestrial planets.

  8. Dictionary of Minor Planet Names

    CERN Document Server

    Schmadel, Lutz

    2012-01-01

    The quantity of numbered minor planets has now well exceeded a quarter million. The new sixth edition of the Dictionary of Minor Planet Names, which is the IAU’s official reference work for the field, now covers more than 17,000 named minor planets. In addition to being of practical value for identification purposes, the Dictionary of Minor Planet Names provides authoritative information on the basis of the rich and colorful variety of ingenious names, from heavenly goddesses to artists, from scientists to Nobel laureates, from historical or political figures to ordinary women and men, from mountains to buildings, as well as a variety of compound terms and curiosities. This sixth edition of the Dictionary of Minor Planet Names has grown by more than 7,000 entries compared to the fifth edition and by more than 2,000 compared to the fifth edition, including its two addenda published in 2006 and 2009. In addition, there are many  corrections, revisions and updates to the entries published in earlier editions....

  9. Unstable Roche-Lobe Overflow of Gaseous Planets

    Science.gov (United States)

    Jackson, Brian

    The discoveries of more than 100 roughly Earth-sized bodies with orbital periods less than 1 day, ultra-short-period planets or candidates (USPs), have challenged planet formation theories, and evidence suggests USPs may be the remnants of gaseous planets that shed their atmospheres. Indeed, many hot Jupiters are near Roche-Lobe overflow (RLO), and tidal decay can push them the rest of the way in. Recent work has shown stable RLO (atmospheres lost via a steady outflow and thin accretion disk) probably cannot produce USPs on its own but suggested unstable RLO (atmospheres quickly shed on dynamical timescales) may. In fact, stable RLO may drive overflowing hot Jupiters into unstable RLO, and by analogy with the common-envelope binaries, the core that remains can drive off the gaseous envelope at the cost of its orbital energy. Wellestablished mass-radius relations for gaseous planets, coupled to simple energy and angular momentum considerations, provide a connection between the observed masses and periods for USPs and their putative progenitor gaseous planets, with few free parameters. We propose to investigate the hypothesis that USPs originate through tidal decay and a combination of stable and unstable Roche-lobe overflow of short-period gaseous planets through the following studies: -We will explore the planetary masses, orbital periods, etc. that produce unstable RLO using the Modules for Experiments in Stellar Astrophysics (MESA) suite. -We will relate the observed periods and masses of USPs to their putative progenitor masses and periods to see whether they are consistent with the unstable RLO hypothesis. This proposal is directly relevant to the Exoplanets Research Program since it seeks to "understand the ... physical processes of exoplanets" and "improve understanding of [their] origins" through "theoretical studies ... and modeling'". We also expect that it will have broad impacts on a variety of astrophysical topics: -Ultra-short period planets could

  10. Dictionary of minor planet names

    CERN Document Server

    Schmadel, Lutz D

    1997-01-01

    Until recently, minor planet name citations were scattered in the astronomical literature, and the origin of many names remained obscure In 1988 the IAU Commission 20 established a study group to elucidate the meanings of asteroid names Later on the author continued in collecting and indexing all new relevant data This book contains the names, and their meanings, of all - as yet 5252 - named minor planets It informs about the discoverers as well as the circumstances of the discovery of all 7041 minor planets that were numbered up to June 1996 In addition to being of practical value for identification purposes, the collection provides a most interesting historical insight into the work of those astronomers who over two centuries vested their affinities in a rich and colourful variety of ingenious names, from heavenly goddesses to more prosaic constructions This third, revised and enlarged edition comprises about 40% more information than was provided with the first one of 1992

  11. Characterizing K2 Planet Discoveries

    Science.gov (United States)

    Vanderburg, Andrew; Montet, Benjamin; Johnson, John; Buchhave, Lars A.; Zeng, Li; Bieryla, Allyson; Latham, David W.; Charbonneau, David; Harps-N Collaboration, The Robo-Ao Team

    2015-01-01

    We present an effort to confirm the first planet discovered by the two-wheeled Kepler mission. We analyzed K2 photometry, correcting for nonuniform detector response as a function of the spacecraft's pointing, and detected a transiting planet candidate. We describe our multi-telescope followup observing campaign, consisting of photometric, spectroscopic, and high resolution imaging observations, including over 40 HARPS-N radial velocity measurements. The new planet is a super-Earth orbiting a bright star amenable to followup observations. HARPS-N was funded by the Swiss Space Office, the Harvard Origin of Life Initiative, the Scottish Universities Physics Alliance, the University of Geneva, the Smithsonian Astrophysical Observatory, the Italian National Astrophysical Institute, the University of St. Andrews, Queens University Belfast, and the University of Edinburgh.

  12. Very high-density planets: a possible remnant of gas giants.

    Science.gov (United States)

    Mocquet, A; Grasset, O; Sotin, C

    2014-04-28

    Data extracted from the Extrasolar Planets Encyclopaedia (see http://exoplanet.eu) show the existence of planets that are more massive than iron cores that would have the same size. After meticulous verification of the data, we conclude that the mass of the smallest of these planets is actually not known. However, the three largest planets, Kepler-52b, Kepler-52c and Kepler-57b, which are between 30 and 100 times the mass of the Earth, have indeed density larger than an iron planet of the same size. This observation triggers this study that investigates under which conditions these planets could represent the naked cores of gas giants that would have lost their atmospheres during their migration towards the star. This study shows that for moderate viscosity values (10(25) Pa s or lower), large values of escape rate and associated unloading stress rate during the atmospheric loss process lead to the explosion of extremely massive planets. However, for moderate escape rate, the bulk viscosity and finite-strain incompressibility of the cores of giant planets can be large enough to retain a very high density during geological time scales. This would make those a new kind of planet, which would help in understanding the interior structure of the gas giants. However, this new family of exoplanets adds some degeneracy for characterizing terrestrial exoplanets.

  13. Dynamical evidence for Planet X

    Science.gov (United States)

    Anderson, John D.; Standish, E. Myles, Jr.

    1986-01-01

    The dynamical evidence for a planet beyond the orbit of Neptune is reviewed. Three years of radio tracking data from Pioneer 10 can be fit to the noise level with no evidence for unmodelled acceleration at a level higher than 5 x 10 to the -14th km/sq s. The evidence does not place severe limits on the Planet X model, but does place a firm limit of five earth masses on a hypothetical comet belt just beyond the orbit of Neptune.

  14. Exploring Mercury: The Iron Planet

    OpenAIRE

    Stevenson, David J.

    2004-01-01

    Planet Mercury is both difficult to observe and difficult to reach by spacecraft. Just one spacecraft, Mariner 10, flew by the planet 30 years ago. An upcoming NASA mission, MESSENGER, will be launched this year and will go into orbit around Mercury at the end of this decade. A European mission is planned for the following decade. It's worth going there because Mercury is a strange body and the history of planetary exploration has taught us that strangeness gives us insight into planetary ori...

  15. Guldlok og de nye planeter

    DEFF Research Database (Denmark)

    Pedersen, Jens Olaf Pepke

    2007-01-01

    De såkaldte exoplaneter, som er planeter i andre solsystemer, beskrivelse af de de betingelser, der skal være opfyldt, før man kan gøre sig håb om at finde liv på dem og de metoder astronomer bruger til at finde planeterne.......De såkaldte exoplaneter, som er planeter i andre solsystemer, beskrivelse af de de betingelser, der skal være opfyldt, før man kan gøre sig håb om at finde liv på dem og de metoder astronomer bruger til at finde planeterne....

  16. Atmospheric dynamics of tidally synchronized extrasolar planets.

    Science.gov (United States)

    Cho, James Y-K

    2008-12-13

    Tidally synchronized planets present a new opportunity for enriching our understanding of atmospheric dynamics on planets. Subject to an unusual forcing arrangement (steady irradiation on the same side of the planet throughout its orbit), the dynamics on these planets may be unlike that on any of the Solar System planets. Characterizing the flow pattern and temperature distribution on the extrasolar planets is necessary for reliable interpretation of data currently being collected, as well as for guiding future observations. In this paper, several fundamental concepts from atmospheric dynamics, likely to be central for characterization, are discussed. Theoretical issues that need to be addressed in the near future are also highlighted.

  17. True polar wander on convecting planets

    Science.gov (United States)

    Rose, Ian Robert

    Rotating planets are most stable when spinning around their maximum moment of inertia, and will tend to reorient themselves to achieve this configuration. Geological activity redistributes mass in the planet, making the moment of inertia a function of time. As the moment of inertia of the planet changes, the spin axis shifts with respect to a mantle reference frame in order to maintain rotational stability. This process is known as true polar wander (TPW). Of the processes that contribute to a planet's moment of inertia, convection in the mantle generates the largest and longest-period fluctuations, with corresponding shifts in the spin axis. True polar wander has been hypothesized to explain several physiographic features on planets and moons in our solar system. On Earth, TPW events have been invoked in some interpretations of paleomagnetic data. Large swings in the spin axis could have enormous ramifications for paleogeography, paleoclimate, and the history of life. Although the existence of TPW is well-verified, it is not known whether its rate and magnitude have been large enough for it to be an important process in Earth history. If true polar wander has been sluggish compared to plate tectonic speeds, then it would be difficult to detect and its consequences would be minor. I investigate rates of true polar wander on convecting planets using scaling, numerics, and inverse problems. I perform a scaling analysis of TPW on a convecting planet, identifying a minimal set of nondimensional parameters which describe the problem. The primary nondimensional numbers that control the rate of TPW are the ratio of centrifugal to gravitational forces m and the Rayleigh number Ra. The parameter m sets the size of a planet's rotational bulge, which determines the amount of work that needs to be done to move the spin axis. The Rayleigh number controls the size, distribution, and rate of change of moment of inertia anomalies, all of which affect the rate of TPW. I find that

  18. Hole-y Debris Disks, Batman! Where are the planets?

    Science.gov (United States)

    Bailey, V.; Meshkat, T.; Hinz, P.; Kenworthy, M.; Su, K. Y. L.

    2014-03-01

    Giant planets at wide separations are rare and direct imaging surveys are resource-intensive, so a cheaper marker for the presence of giant planets is desirable. One intriguing possibility is to use the effect of planets on their host stars' debris disks. Theoretical studies indicate giant planets can gravitationally carve sharp boundaries and gaps in their disks; this has been seen for HR 8799, β Pic, and tentatively for HD 95086 (Su et al. 2009, Lagrange et al. 2010, Moor et al. 2013). If more broadly demonstrated, this link could help guide target selection for next generation direct imaging surveys. Using Spitzer MIPS/IRS spectral energy distributions (SEDs), we identify several dozen systems with two-component and/or large inner cavity disks (aka Hole-y Debris Disks). With LBT/LBTI, VLT/NaCo, GeminiS/NICI, MMT/Clio and Magellan/Clio, we survey a subset these SEDselected targets (~20). In contrast to previous disk-selected planet surveys (e.g.: Janson et al. 2013, Wahhaj et al. 2013) we image primarily in the thermal IR (L'-band), where planet-to-star contrast is more favorable and background contaminants less numerous. Thus far, two of our survey targets host planet-mass companions, both of which were discovered in L'-band after they were unrecognized or undetectable in H-band. For each system in our sample set, we will investigate whether the known companions and/or companions below our detection threshold could be responsible for the disk architecture. Ultimately, we will increase our effective sample size by incorporating detection limits from surveys that have independently targeted some of our systems of interest. In this way we will refine the conditions under which disk SED-based target selection is likely to be useful and valid.

  19. Rainbows, polarization, and the search for habitable planets.

    Science.gov (United States)

    Bailey, Jeremy

    2007-04-01

    Current proposals for the characterization of extrasolar terrestrial planets rest primarily on the use of spectroscopic techniques. While spectroscopy is effective in detecting the gaseous components of a planet's atmosphere, it provides no way of detecting the presence of liquid water, the defining characteristic of a habitable planet. In this paper, I investigate the potential of an alternative technique for characterizing the atmosphere of a planet using polarization. By looking for a polarization peak at the "primary rainbow" scattering angle, it is possible to detect the presence of liquid droplets in a planet's atmosphere and constrain the nature of the liquid through its refractive index. Single scattering calculations are presented to show that a well-defined rainbow scattering peak is present over the full range of likely cloud droplet sizes and clearly distinguishes the presence of liquid droplets from solid particles such as ice or dust. Rainbow scattering has been used in the past to determine the nature of the cloud droplets in the Venus atmosphere and by the POLarization and Directionality of Earth Reflectances (POLDER) instrument to distinguish between liquid and ice clouds in the Earth atmosphere. While the presence of liquid water clouds does not guarantee the presence of water at the surface, this technique could complement spectroscopic techniques for characterizing the atmospheres of potential habitable planets. The disk-integrated rainbow peak for Earth is estimated to be at a degree of polarization of 12.7% or 15.5% for two different cloud cover scenarios. The observation of this rainbow peak is shown to be feasible with the proposed Terrestrial Planet Finder Coronograph mission in similar total integration times to those required for spectroscopic characterization.

  20. Challenges in Discerning Atmospheric Composition in Directly Imaged Planets

    Science.gov (United States)

    Marley, Mark S.

    2017-01-01

    One of the justifications motivating efforts to detect and characterize young extrasolar giant planets has been to measure atmospheric composition for comparison with that of the primary star. If the enhancement of heavy elements in the atmospheres of extrasolar giant planets, like it is for their solar system analogs, is inversely proportional to mass, then it is likely that these worlds formed by core accretion. However in practice it has been very difficult to constrain metallicity because of the complex effect of clouds. Cloud opacity varies both vertically and, in some cases, horizontally through the atmosphere. Particle size and composition, both of which impact opacity, are difficult challenges both for forward modeling and retrieval studies. In my presentation I will discuss systematic efforts to improve cloud studies to enable more reliable determinations of atmospheric composition. These efforts are relevant both to discerning composition of directly imaged young planets from ground based telescopes and future space based missions, such as WFIRST and LUVOIR.

  1. Finding Spring on Planet X

    Science.gov (United States)

    Simoson, Andrew J.

    2007-01-01

    For a given orbital period and eccentricity, we determine the maximum time lapse between the winter solstice and the spring equinox on a planet. In addition, given an axial precession path, we determine the effects on the seasons. This material can be used at various levels to illustrate ideas such as periodicity, eccentricity, polar coordinates,…

  2. Monster telescope hunts blue planets

    CERN Multimedia

    Leake, J

    2003-01-01

    BRITAIN is to back a project to build the world's biggest telescope - so powerful that it could see life-bearing planets in other solar systems. It will need the largest mirror ever built at about 100 metres in diameter (1/2 page).

  3. MEMS AO for Planet Finding

    Science.gov (United States)

    Rao, Shanti; Wallace, J. Kent; Shao, Mike; Schmidtlin, Edouard; Levine, B. Martin; Samuele, Rocco; Lane, Benjamin; Chakrabarti, Supriya; Cook, Timothy; Hicks, Brian; hide

    2008-01-01

    This slide presentation reviews a method for planet finding using microelectromechanical systems (MEMS) Adaptive Optics (AO). The use of a deformable mirror (DM) is described as a part of the instrument that was designed with a nulling interferometer. The strategy that is used is described in detail.

  4. Tracking Planets around the Sun

    Science.gov (United States)

    Riddle, Bob

    2008-01-01

    In earlier columns, the celestial coordinate system of hour circles of right ascension and degrees of declination was introduced along with the use of an equatorial star chart (see SFA Star Charts in Resources). This system shows the planets' motion relative to the ecliptic, the apparent path the Sun follows during the year. An alternate system,…

  5. Jupiter: Lord of the Planets.

    Science.gov (United States)

    Kaufmann, William

    1984-01-01

    Presents a chapter from an introductory college-level astronomy textbook in which full-color photographs and numerous diagrams highlight an extensive description of the planet Jupiter. Topics include Jupiter's geology, rotation, magnetic field, atmosphere (including clouds and winds), and the Great Red Spot. (DH)

  6. Venus and Mercury as Planets

    Science.gov (United States)

    1974-01-01

    A general evolutionary history of the solar planetary system is given. The previously observed characteristics of Venus and Mercury (i.e. length of day, solar orbit, temperature) are discussed. The role of the Mariner 10 space probe in gathering scientific information on the two planets is briefly described.

  7. A rocky planet transiting a nearby low-mass star.

    Science.gov (United States)

    Berta-Thompson, Zachory K; Irwin, Jonathan; Charbonneau, David; Newton, Elisabeth R; Dittmann, Jason A; Astudillo-Defru, Nicola; Bonfils, Xavier; Gillon, Michaël; Jehin, Emmanuël; Stark, Antony A; Stalder, Brian; Bouchy, Francois; Delfosse, Xavier; Forveille, Thierry; Lovis, Christophe; Mayor, Michel; Neves, Vasco; Pepe, Francesco; Santos, Nuno C; Udry, Stéphane; Wünsche, Anaël

    2015-11-12

    M-dwarf stars--hydrogen-burning stars that are smaller than 60 per cent of the size of the Sun--are the most common class of star in our Galaxy and outnumber Sun-like stars by a ratio of 12:1. Recent results have shown that M dwarfs host Earth-sized planets in great numbers: the average number of M-dwarf planets that are between 0.5 to 1.5 times the size of Earth is at least 1.4 per star. The nearest such planets known to transit their star are 39 parsecs away, too distant for detailed follow-up observations to measure the planetary masses or to study their atmospheres. Here we report observations of GJ 1132b, a planet with a size of 1.2 Earth radii that is transiting a small star 12 parsecs away. Our Doppler mass measurement of GJ 1132b yields a density consistent with an Earth-like bulk composition, similar to the compositions of the six known exoplanets with masses less than six times that of the Earth and precisely measured densities. Receiving 19 times more stellar radiation than the Earth, the planet is too hot to be habitable but is cool enough to support a substantial atmosphere, one that has probably been considerably depleted of hydrogen. Because the host star is nearby and only 21 per cent the radius of the Sun, existing and upcoming telescopes will be able to observe the composition and dynamics of the planetary atmosphere.

  8. THE ANGLO-AUSTRALIAN PLANET SEARCH. XXII. TWO NEW MULTI-PLANET SYSTEMS

    Energy Technology Data Exchange (ETDEWEB)

    Wittenmyer, Robert A.; Horner, J.; Salter, G. S.; Tinney, C. G.; Bailey, J. [Department of Astrophysics, School of Physics, University of New South Wales, Sydney, NSW 2052 (Australia); Tuomi, Mikko; Zhang, Z. [Centre for Astrophysics Research, Science and Technology Research Institute, University of Hertfordshire, College Lane, Hatfield AL10 9AB (United Kingdom); Butler, R. P. [Department of Terrestrial Magnetism, Carnegie Institution of Washington, 5241 Broad Branch Road, NW, Washington, DC 20015-1305 (United States); Jones, H. R. A. [Centre for Astrophysics Research, University of Hertfordshire, College Lane, Hatfield, AL10 9AB (United Kingdom); O' Toole, S. J. [Australian Astronomical Observatory, P.O. Box 296, Epping, NSW 1710 (Australia); Carter, B. D. [Faculty of Sciences, University of Southern Queensland, Toowoomba, Queensland 4350 (Australia); Jenkins, J. S. [Departamento de Astronomia, Universidad de Chile, Camino El Observatorio 1515, Las Condes, Santiago (Chile); Vogt, S. S.; Rivera, Eugenio J., E-mail: rob@phys.unsw.edu.au [UCO/Lick Observatory, University of California, Santa Cruz, CA 95064 (United States)

    2012-07-10

    We report the detection of two new planets from the Anglo-Australian Planet Search. These planets orbit two stars each previously known to host one planet. The new planet orbiting HD 142 has a period of 6005 {+-} 427 days, and a minimum mass of 5.3 M{sub Jup}. HD 142c is thus a new Jupiter analog: a gas-giant planet with a long period and low eccentricity (e = 0.21 {+-} 0.07). The second planet in the HD 159868 system has a period of 352.3 {+-} 1.3 days and m sin i = 0.73 {+-} 0.05 M{sub Jup}. In both of these systems, including the additional planets in the fitting process significantly reduced the eccentricity of the original planet. These systems are thus examples of how multiple-planet systems can masquerade as moderately eccentric single-planet systems.

  9. Probing Protoplanetary Disks: From Birth to Planets

    Science.gov (United States)

    Guilfoil Cox, Erin

    2018-01-01

    Disks are very important in the evolution of protostars and their subsequent planets. How early disks can form has implications for early planet formation. In the youngest protostars (i.e., Class 0 sources) magnetic fields can control disk growth. When the field is parallel to the collapsing core’s rotation axis, infalling material loses angular momentum and disks form in later stages. Sub-/millimeter polarization continuum observations of Class 0 sources at ~1000 au resolution support this idea. However, in the inner (~100 au), denser regions, it is unknown if the polarization only traces aligned dust grains. Recent theoretical studies have shown that self-scattering of thermal emission in the disk may contribute significantly to the polarization. Determining the scattering contribution in these sources is important to disentangle the magnetic field. At older times (the Class II phase), the disk structure can both act as a modulator and signpost of planet formation, if there is enough of a mass reservoir. In my dissertation talk, I will present results that bear on disk evolution at both young and late ages. I will present 8 mm polarization results of two Class 0 protostars (IRAS 4A and IC348 MMS) from the VLA at ~50 au resolution. The inferred magnetic field of IRAS 4A has a circular morphology, reminiscent of material being dragged into a rotating structure. I will show results from SOFIA polarization data of the area surrounding IRAS 4A at ~4000 au. I will also present ALMA 850 micron polarization data of ten protostars in the Perseus Molecular Cloud. Most of these sources show very ordered patterns and low (~0.5%) polarization in their inner regions, while having very disordered patterns and high polarization patterns in their extended emission that may suggest different mechanisms in the inner/outer regions. Finally, I will present results from our ALMA dust continuum survey of protoplanetary disks in Rho Ophiuchus; we measured both the sizes and fluxes of

  10. The Earth: A Changing Planet

    Science.gov (United States)

    Ribas, Núria; Màrquez, Conxita

    2013-04-01

    text: We describe a didactic unit that rises from our own living impression about our experience on the planet. Most of us feel the Earth to be a very static place. Rocks don't easily move and most landscapes always look the same over time. Anyone would say (the same way most scientists believed until the beginning of the last century) that our planet has always remained unchanged, never transformed. But then, all of a sudden, as a misfortune for so many humans, natural hazards appear on the scene: an earthquake causing so many disasters, a tsunami carrying away everything in its path, an eruption that can destroy huge surrounding areas but also bring new geographical relief. Science cannot remain oblivious to these events, we must wonder beyond. What does an earthquake mean? Why does it happen? What about an eruption? If it comes from the inside, what can we guess from it? Researching about all of these events, scientists have been able to arrive to some important knowledge of the planet itself: It has been possible to theorize about Earth's interior. It has also been confirmed that the planet has not always been the quiet and stable place we once thought. Continents, as Wegener supposed, do move about and the Tectonic Plates Theory, thanks to the information obtained through earthquakes and eruption, can provide some interesting explanations. But how do we know about our planet's past? How can we prove that the Earth has always been moving and that its surface changes? The Earth's rocks yield the answer. Rocks have been the only witnesses throughout millions of years, since the planet first came to existence. Let's learn how to read them… Shouldn't we realize that rocks are to Geology what books are to History? This discursive process has been distributed in four learning sequences: 1. Land is not as solid nor firm as it would seem, 2. The Earth planet: a puzzle, 3. The rocks also recycle , 4. Field trip to "Sant Miquel del Fai". The subjects take about 30

  11. Comparative Climatology of Terrestrial Planets

    Science.gov (United States)

    Mackwell, Stephen J.; Simon-Miller, Amy A.; Harder, Jerald W.; Bullock, Mark A.

    Public awareness of climate change on Earth is currently very high, promoting significant interest in atmospheric processes. We are fortunate to live in an era where it is possible to study the climates of many planets, including our own, using spacecraft and groundbased observations as well as advanced computational power that allows detailed modeling. Planetary atmospheric dynamics and structure are all governed by the same basic physics. Thus differences in the input variables (such as composition, internal structure, and solar radiation) among the known planets provide a broad suite of natural laboratory settings for gaining new understanding of these physical processes and their outcomes. Diverse planetary settings provide insightful comparisons to atmospheric processes and feedbacks on Earth, allowing a greater understanding of the driving forces and external influences on our own planetary climate. They also inform us in our search for habitable environments on planets orbiting distant stars, a topic that was a focus of Exoplanets, the preceding book in the University of Arizona Press Space Sciences Series. Quite naturally, and perhaps inevitably, our fascination with climate is largely driven toward investigating the interplay between the early development of life and the presence of a suitable planetary climate. Our understanding of how habitable planets come to be begins with the worlds closest to home. Venus, Earth, and Mars differ only modestly in their mass and distance from the Sun, yet their current climates could scarcely be more divergent. Our purpose for this book is to set forth the foundations for this emerging science and to bring to the forefront our current understanding of atmospheric formation and climate evolution. Although there is significant comparison to be made to atmospheric processes on nonterrestrial planets in our solar system — the gas and ice giants — here we focus on the terrestrial planets, leaving even broader comparisons

  12. Planet Detection Algorithms for the Terrestrial Planet Finder-C

    Science.gov (United States)

    Kasdin, N. J.; Braems, I.

    2005-12-01

    Critical to mission planning for the terrestrial planet finder coronagraph (TPF-C) is the ability to estimate integration times for planet detection. This detection is complicated by the presence of background noise due to local and exo-zodiacal dust, by residual speckle due optical errors, and by the dependence of the PSF shape on the specific coronagraph. In this paper we examine in detail the use of PSF fitting (matched filtering) for planet detection, derive probabilistic bounds for the signal-to-noise ratio by balancing missed detection and false alarm rates, and demonstrate that this is close to the optimal linear detection technique. We then compare to a Bayesian detection approach and show that for very low background the Bayesian method offers integration time improvements, but rapidly approaches the PSF fitting result for reasonable levels of background noise. We confirm via monte-carlo simulations. This work was supported under a grant from the Jet Propulsion Laboratory and by a fellowship from the Institut National de Recherche en Informatique et Automatique (INRIA).

  13. Born dry in the photoevaporation desert: Kepler's ultra-short-period planets formed water-poor

    Science.gov (United States)

    Lopez, Eric D.

    2017-11-01

    Recent surveys have uncovered an exciting new population of ultra-short-period (USP) planets with orbital periods less than a day. These planets typically have radii ≲1.5 R⊕, indicating that they likely have rocky compositions. This stands in contrast to the overall distribution of planets out to ˜100 d, which is dominated by low-density sub-Neptunes above 2 R⊕, which must have gaseous envelopes to explain their size. However, on the USP orbits, planets are bombarded by intense levels of photoionizing radiation and consequently gaseous sub-Neptunes are extremely vulnerable to losing their envelopes to atmospheric photoevaporation. Using models of planet evolution, I show that the rocky USP planets can easily be produced as the evaporated remnants of sub-Neptunes with H/He envelopes and that we can therefore understand the observed dearth of USP sub-Neptunes as a natural consequence of photoevaporation. Critically however, planets on USP orbits could often retain their envelopes if they are formed with very high-metallicity water-dominated envelopes. Such water-rich planets would commonly be ≳2 R⊕ today, which is inconsistent with the observed evaporation desert, indicating that most USP planets likely formed from water-poor material within the snow-line. Finally, I examine the special case of 55 Cancri e and its possible composition in the light of recent observations, and discuss the prospects for further characterizing this population with future observations.

  14. The same frequency of planets inside and outside open clusters of stars.

    Science.gov (United States)

    Meibom, Søren; Torres, Guillermo; Fressin, Francois; Latham, David W; Rowe, Jason F; Ciardi, David R; Bryson, Steven T; Rogers, Leslie A; Henze, Christopher E; Janes, Kenneth; Barnes, Sydney A; Marcy, Geoffrey W; Isaacson, Howard; Fischer, Debra A; Howell, Steve B; Horch, Elliott P; Jenkins, Jon M; Schuler, Simon C; Crepp, Justin

    2013-07-04

    Most stars and their planets form in open clusters. Over 95 per cent of such clusters have stellar densities too low (less than a hundred stars per cubic parsec) to withstand internal and external dynamical stresses and fall apart within a few hundred million years. Older open clusters have survived by virtue of being richer and denser in stars (1,000 to 10,000 per cubic parsec) when they formed. Such clusters represent a stellar environment very different from the birthplace of the Sun and other planet-hosting field stars. So far more than 800 planets have been found around Sun-like stars in the field. The field planets are usually the size of Neptune or smaller. In contrast, only four planets have been found orbiting stars in open clusters, all with masses similar to or greater than that of Jupiter. Here we report observations of the transits of two Sun-like stars by planets smaller than Neptune in the billion-year-old open cluster NGC6811. This demonstrates that small planets can form and survive in a dense cluster environment, and implies that the frequency and properties of planets in open clusters are consistent with those of planets around field stars in the Galaxy.

  15. Growing and moving planets in disks

    NARCIS (Netherlands)

    Paardekooper, Sijme-Jan

    2006-01-01

    Planets form in disks that are commonly found around young stars. The intimate relationship that exists between planet and disk can account for a lot of the exotic extrasolar planetary systems known today. In this thesis we explore disk-planet interaction using numerical hydrodynamical simulations.

  16. The Use of Planisphere to Locate Planets

    Science.gov (United States)

    Kwok, Ping-Wai

    2013-01-01

    Planisphere is a simple and useful tool in locating constellations of the night sky at a specific time, date and geographic location. However it does not show the planet positions because planets are not fixed on the celestial sphere. It is known that the planet orbital planes are nearly coplanar and close to the ecliptic plane. By making…

  17. YETI – search for young transiting planets******

    Directory of Open Access Journals (Sweden)

    Neuhäuser Ralph

    2013-04-01

    Full Text Available We present our search for young transiting planets at ages of 2 to 20 Myr. Towards this goal, we monitor a number of young open clusters with the YETI network. YETI consists of 0.4-2 m-sized telescopes at different longitudes that observe continuously over timescales much longer than a night. In our first cluster Trumpler 37 we found more than 350 variable stars. Also two transiting candidates were found so far, for which follow-up is partly done. The first candidate turned out to be an eclipsing binary with an M-type companion. We describe the research done on these two transiting candidates.

  18. Host Star Evolution for Planet Habitability.

    Science.gov (United States)

    Gallet, Florian; Charbonnel, Corinne; Amard, Louis

    2016-11-01

    With about 2000 exoplanets discovered within a large range of different configurations of distance from the star, size, mass, and atmospheric conditions, the concept of habitability cannot rely only on the stellar effective temperature anymore. In addition to the natural evolution of habitability with the intrinsic stellar parameters, tidal, magnetic, and atmospheric interactions are believed to have strong impact on the relative position of the planets inside the so-called habitable zone. Moreover, the notion of habitability itself strongly depends on the definition we give to the term "habitable". The aim of this contribution is to provide a global and up-to-date overview of the work done during the last few years about the description and the modelling of the habitability, and to present the physical processes currently includes in this description.

  19. The case against Planet X.

    Science.gov (United States)

    Goldreich, P.; Ward, W. R.

    1972-01-01

    The dynamical consequences of the hypothetical trans-Plutonian planet suggested by Brady (1972) are considered. It is concluded that the combination of large mass and unusual orbital inclination would have two serious effects on the solar system. The angle between the solar axis and the normal to the ecliptic would suffer large variations with a period of a few times ten million years, and the coplanar configuration of the outer solar system would be disrupted on a time scale of 1 m.y. The large residuals in the orbit of Halley's comet which prompted the suggestion of a trans-Plutonian planet can be explained in terms of nongravitation forces and the weak orbital binding energy of this object.

  20. Observational biases for transiting planets

    Science.gov (United States)

    Kipping, David M.; Sandford, Emily

    2016-12-01

    Observational biases distort our view of nature, such that the patterns we see within a surveyed population of interest are often unrepresentative of the truth we seek. Transiting planets currently represent the most informative data set on the ensemble properties of exoplanets within 1 au of their star. However, the transit method is inherently biased due to both geometric and detection-driven effects. In this work, we derive the overall observational biases affecting the most basic transit parameters from first principles. By assuming a trapezoidal transit and using conditional probability, we infer the expected distribution of these terms both as a joint distribution and in a marginalized form. These general analytic results provide a baseline against which to compare trends predicted by mission-tailored injection/recovery simulations and offer a simple way to correct for observational bias. Our results explain why the observed population of transiting planets displays a non-uniform impact parameter distribution, with a bias towards near-equatorial geometries. We also find that the geometric bias towards observed planets transiting near periastron is attenuated by the longer durations which occur near apoastron. Finally, we predict that the observational bias with respect to ratio-of-radii is super-quadratic, scaling as (RP/R⋆)5/2, driven by an enhanced geometric transit probability and modestly longer durations.

  1. The Giant Planet Satellite Exospheres

    Science.gov (United States)

    McGrath, M. A.

    2014-12-01

    Exospheres are relatively common in the outer solar system among the moons of the gas giant planets. They span the range from very tenuous, surface-bounded exospheres (e.g., Rhea, Dione) to quite robust exospheres with exobase above the surface (e.g., Io, Triton), and include many intermediate cases (e.g., Europa, Ganymede, Enceladus). The exospheres of these moons exhibit an interesting variety of sources, from surface sputtering, to frost sublimation, to active plumes, and also well illustrate another common characteristic of the outer planet satellite exospheres, namely, that the primary species often exists both as a gas in atmosphere, and a condensate (frost or ice) on the surface. As described by Yelle et al. (1995) for Triton, "The interchange of matter between gas and solid phases on these bodies has profound effects on the physical state of the surface and the structure of the atmosphere." A brief overview of the exospheres of the outer planet satellites will be presented, including an inter-comparison of these satellites exospheres with each other, and with the exospheres of the Moon and Mercury.

  2. Celestial mechanics of planet shells

    Science.gov (United States)

    Barkin, Yu V.; Vilke, V. G.

    2004-06-01

    The motion of a planet consisting of an external shell (mantle) and a core (rigid body), which are connected by a visco-elastic layer and mutually gravitationally interact with each other and with an external celestial body (considered as a material point), is studied (Barkin, 1999, 2002a,b; Vilke, 2004). Relative motions of the core and mantle are studied on the assumption that the centres of mass of the planet and external body move on unperturbed Keplerian orbits around the general centre of mass of the system. The core and mantle of the planet have axial symmetry and have different principal moments of inertia. The differential action of the external body on the core and mantle cause the periodic relative displacements of their centres of mass and their relative turns. An approximate solution of the problem was obtained on the basis of the linearization, averaging and small-parameter methods. The obtained analytical results are applied to the study of the possible relative displacements of the core and mantle of the Earth under the gravitational action of the Moon. For the suggested two-body Earth model and in the simple case of a circular (model) lunar orbit the new phenomenon of periodic translatory-rotary oscillations of the core with a fortnightly period the mantle was observed. The more remarkable phenomenon is the cyclic rotation with the same period (13.7 days) of the core relative to the mantle with a ‘large’ amplitude of 152 m (at the core surface).The results obtained confirm the general concept described by Barkin (1999, 2002a,b) that induced relative shell oscillations can control and dictate the cyclic and secular processes of energization of the planets and satellites in definite rhythms and on different time scales.The results obtained mean that giant moments and forces produce energy which causes in particular deformations of the viscoelastic layer between planet shells. This process is realized with different intensities on different time

  3. Planets, pluralism, and conceptual lineage

    Science.gov (United States)

    Brusse, Carl

    2016-02-01

    Conceptual change can occur for a variety of reasons; some more scientifically significant than others. The 2006 definition of 'planet', which saw Pluto reclassified as a dwarf planet, is an example toward the more mundane end of the scale. I argue however that this case serves as a useful example of a related phenomenon, whereby what appears to be a single kind term conceals two or more distinct concepts with independent scientific utility. I examine the historical background to this case, as a template for developing additional evidence for pluralist approaches to conceptual disputes within science and elsewhere. "I would like to note that the two speakers who have spoken so far have both done the same extremely insulting gaffe," he said. "They have used the expression 'a physical definition of a planet' - by implication, suggesting that a dynamical definition is not physics!" He said he felt he had to teach the panel "something you should know": that dynamics was indeed physics, and in fact was addressed before solid-state physics in every textbook ever written." (Boyle, 2010, p. 126)

  4. Atmospheric Dynamics of Irradiated Planets

    Science.gov (United States)

    Dobbs-Dixon, Ian

    2009-09-01

    Close-in gas giant planets are now familiar members of the growing family of extra-solar planets. Their short period orbits and proclivity for transiting has made them the target of numerous observational campaigns, and our knowledge of their structure and composition has increased dramatically over the past few years. However, despite their prevalence and important role in constraining a wide range of planetary models, fundamental questions about the dynamical behavior of their atmospheres remain, crucial for interpreting observations. I will discuss three-dimensional radiative hydrodynamical simulations of atmospheric flows on a wide variety of such objects, ranging from the well-known HD209458b to the more exotic rapidly rotating or highly eccentric objects. Such objects exhibit a range of unusual behavior including supersonic winds, shocks and instabilities, and time dependent behavior. I will review the results from models we have developed to study these processes with the goal of both explaining individual objects and the observed diversity among this class of planets.

  5. Towards the Rosetta Stone of planet formation

    Directory of Open Access Journals (Sweden)

    Schmidt T.O.B.

    2011-02-01

    Full Text Available Transiting exoplanets (TEPs observed just ~10 Myrs after formation of their host systems may serve as the Rosetta Stone for planet formation theories. They would give strong constraints on several aspects of planet formation, e.g. time-scales (planet formation would then be possible within 10 Myrs, the radius of the planet could indicate whether planets form by gravitational collapse (being larger when young or accretion growth (being smaller when young. We present a survey, the main goal of which is to find and then characterise TEPs in very young open clusters.

  6. Kepler Planet-Detection Mission: Introduction and First Results

    OpenAIRE

    Borucki, William J.; Koch, David; Basri, Gibor; Batalha, Natalie; Brown, Timothy; Caldwell, Douglas; Caldwell, John; Christensen-Dalsgaard, Jørgen; Cochran, William D.; Devore, Edna; Dunham, Edward W.; Dupree, Andrea K.; Gauthier, Thomas N., III; Geary, John C.; Gilliland, Ronald

    2010-01-01

    The Kepler mission was designed to determine the frequency of Earth-sized planets in and near the habitable zone of Sun-like stars. The habitable zone is the region where planetary temperatures are suitable for water to exist on a planet’s surface. During the first 6 weeks of observations, Kepler monitored 156,000 stars, and five new exoplanets with sizes between 0.37 and 1.6 Jupiter radii and orbital periods from 3.2 to 4.9 days were discovered. The density of the Neptune-sized Kepler-4b is ...

  7. Evolution of Motion of a Binary Planet

    Science.gov (United States)

    Vil'ke, V. G.; Shatina, A. V.

    2001-05-01

    A model of a binary planet, consisting of a material point of small mass and a deformable viscoelastic sphere, is suggested. The center of mass of the binary planet moves in the gravitational field of a central body in the plane, which contains planets forming the binary planet. A deformable spherical planet rotates around the axis orthogonal to the plane of planetary motion. Planet deformations are described by the linear theory of viscoelasticity. It is shown that with an appropriate approximation of the gravitational potential, there is a class of quasicircular orbits, when the eccentricities of an orbit of the center of mass of a binary planet and an orbit, describing mutual planet motion, are equal to zero. The further evolution of motion is investigated in this class of orbits with the use of the canonical Poincare-Andoyer variables. Corresponding averaged equations are found, and phase pictures are constructed; the stability of stationary solutions is investigated on the basis of equations in variations. For the Solar system planets with their satellites, forming binary planets, the application of the presented model allows us to conclude that satellites sooner or later will fall on the corresponding planets.

  8. Planetary Systems and the Formation of Habitable Planets

    Science.gov (United States)

    Dvorak, Rudolf; Maindl, Thomas I.; Burger, Christoph; Schäfer, Christoph; Speith, Roland

    2015-09-01

    As part of a national scientific network 'Pathways to Habitability' the formation of planets and the delivery of water onto these planets is a key question as water is essential for the development of life. In the first part of the paper we summarize the state of the art of planet formation - which is still under debate in the astronomical community - before we show our results on this topic. The outcome of our numerical simulations depends a lot on the choice of the initial distribution of planetesimals and planetary embryos after gas disappeared in the protoplanetary disk. We also take into account that some of these planetesimals of sizes in the order of the mass of the Moon already contained water; the quantity depends on the distance from the Sun - close-by bodies are dry, but starting from a distance of about 2 AU they can contain substantial amounts of water. We assume that the gas giants and terrestrial planets are already formed when we check the collisions of the small bodies containing water (in the order of a few percent) with the terrestrial planets. We thus are able to give an estimate of the respective contribution to the actual water content (of some Earth-oceans) in the mantle, in the crust and on the surface of Earth. In the second part we discuss in more detail how the formation of larger bodies after a collision may happen as the outcome depends on parameters like collision velocity, impact angle, and the materials involved. We present results obtained by SPH (Smooth Particle Hydrodynamics) simulations. We briefly describe this method and show different scenarios with respect to the formed bodies, possible fragmentation and the water content before and after the collision. In an appendix we discuss detection methods for extrasolar planets (close to 2000 such objects have been discovered so far).

  9. Exploring the diversity of Jupiter-class planets.

    Science.gov (United States)

    Fletcher, Leigh N; Irwin, Patrick G J; Barstow, Joanna K; de Kok, Remco J; Lee, Jae-Min; Aigrain, Suzanne

    2014-04-28

    Of the 900+ confirmed exoplanets discovered since 1995 for which we have constraints on their mass (i.e. not including Kepler candidates), 75% have masses larger than Saturn (0.3 MJ), 53% are more massive than Jupiter and 67% are within 1 AU of their host stars. When Kepler candidates are included, Neptune-sized giant planets could form the majority of the planetary population. And yet the term 'hot Jupiter' fails to account for the incredible diversity of this class of astrophysical object, which exists on a continuum of giant planets from the cool jovians of our own Solar System to the highly irradiated, tidally locked hot roasters. We review theoretical expectations for the temperatures, molecular composition and cloud properties of hydrogen-dominated Jupiter-class objects under a variety of different conditions. We discuss the classification schemes for these Jupiter-class planets proposed to date, including the implications for our own Solar System giant planets and the pitfalls associated with compositional classification at this early stage of exoplanetary spectroscopy. We discuss the range of planetary types described by previous authors, accounting for (i) thermochemical equilibrium expectations for cloud condensation and favoured chemical stability fields; (ii) the metallicity and formation mechanism for these giant planets; (iii) the importance of optical absorbers for energy partitioning and the generation of a temperature inversion; (iv) the favoured photochemical pathways and expectations for minor species (e.g. saturated hydrocarbons and nitriles); (v) the unexpected presence of molecules owing to vertical mixing of species above their quench levels; and (vi) methods for energy and material redistribution throughout the atmosphere (e.g. away from the highly irradiated daysides of close-in giants). Finally, we discuss the benefits and potential flaws of retrieval techniques for establishing a family of atmospheric solutions that reproduce the

  10. The Potential for Volcanism and Tectonics on Extrasolar Terrestrial Planets

    Science.gov (United States)

    Quick, Lynnae C.; Roberge, Aki

    2018-01-01

    JWST and other next-generation space telescopes (e.g., LUVOIR, HabEx, & OST) will usher in a new era of exoplanet characterization that may lead to the identification of habitable, Earth-like worlds. Like the planets and moons in our solar system, the surfaces and interiors of terrestrial exoplanets may be shaped by volcanism and tectonics (Fu et al., 2010; van Summeren et al., 2011; Henning and Hurford, 2014). The magnitude and rate of occurrence of these dynamic processes can either facilitate or preclude the existence of habitable environments. Likewise, it has been suggested that detections of cryovolcanism on icy exoplanets, in the form of geyser-like plumes, could indicate the presence of subsurface oceans (Quick et al., 2017).The presence of volcanic and tectonic activity on solid exoplanets will be intimately linked to planet size and heat output in the form of radiogenic and/or tidal heating. In order to place bounds on the potential for such activity, we estimated the heat output of a variety of exoplanets observed by Kepler. We considered planets whose masses and radii range from 0.067 ME (super-Ganymede) to 8 ME (super-Earth), and 0.5 to 1.8 RE, respectively. These heat output estimates were then compared to those of planets, moons, and dwarf planets in our solar system for which we have direct evidence for the presence/absence of volcanic and tectonic activity. After exoplanet heating rates were estimated, depths to putative molten layers in their interiors were also calculated. For planets such as TRAPPIST-1h, whose densities, orbital parameters, and effective temperatures are consistent with the presence of significant amounts of H2O (Luger et al., 2017), these calculations reveal the depths to internal oceans which may serve as habitable niches beneath surface ice layers.

  11. The Detection and Characterization of Extrasolar Planets

    Directory of Open Access Journals (Sweden)

    Ken Rice

    2014-09-01

    Full Text Available We have now confirmed the existence of > 1800 planets orbiting stars other thanthe Sun; known as extrasolar planets or exoplanets. The different methods for detectingsuch planets are sensitive to different regions of parameter space, and so, we are discoveringa wide diversity of exoplanets and exoplanetary systems. Characterizing such planets isdifficult, but we are starting to be able to determine something of their internal compositionand are beginning to be able to probe their atmospheres, the first step towards the detectionof bio-signatures and, hence, determining if a planet could be habitable or not. Here, Iwill review how we detect exoplanets, how we characterize exoplanetary systems and theexoplanets themselves, where we stand with respect to potentially habitable planets and howwe are progressing towards being able to actually determine if a planet could host life or not.

  12. Wandering stars. About planets and exo-planets: an introductory notebook

    Science.gov (United States)

    Cole, George H. A.

    pt. I. Observations reveal gravity. 1. Early observations. 1.1. Stars and planets. 1.2. Interpretations of the observations. 1.3. Sun, moon and earth. 1.4. The shapes of the orbits. 1.5. Kepler's laws of planetary motion. 1.6. Galileo's law of inertia: Newton's laws of motion. 1.7. Newton's law of gravitation. 1.8. A passing encounter without capture. 2. A planet and a sun: the role of gravity. 2.1. Specification of an elliptic orbit. 2.2. Equal areas in equal times. 2.3. Consequences of an elliptical path: the inverse square force law. 2.4. The semi-major axis and the period of the orbit: the 3rd law. 2.5. Two immediate consequences. 2.6. The energy in an elliptic orbit. 2.7. Specifying the orbit from observations. 2.8. The different possible orbits -- 3. Several planets: the centre of mass. 3.1. More than one planet. 3.2. Jupiter, Mars and the asteroids. 3.3. The centre of mass: two masses. 3.4. Transfer orbits. 3.5. Tidal forces. 3.6. The Roche limit. 4. The general structure of a planet. 4.1. Several energies. 4.2. Packing atoms together. 4.3. The mass-radius relation. 4.4. Maximum size and mass. 4.5. Defining a planetary body. 4.6. Cosmic bodies. 4.7. Planets and satellites: planetary bodies. 5. Fluid flows and magnetism. 5.1. The fluid state. 5.2. The importance of time scales. 5.3. Specifying fluid behaviour. 5.4. Isothermal insulating fluids. 5.5. Thermal insulating fluid flows. 5.6. Natural convection: volcanic activities. 5.7. Boundary conditions. 5.8. Electrically conducting fluids. 5.9. Application to planetary magnetic fields -- pt. II. General features of the Solar System. 6. The larger members of the Solar System. 6.1. The sun. 6.2. The planets. 6.3. Satellites. 6.4. Planetary rings. 6.5. Angular momentum. 6.6. Magnetism and rotation. 7. Smaller members: asteroids, comets and meteorites. 7.1. Asteriods. 7.2. Comets and meteor showers. 7.3. Meteorites. 7.4. The Edgeworth-Kuiper belt. 7.5. The Oort cloud. 8. The material of the Solar System. 8.1. The

  13. Lunar and terrestrial planet formation in the Grand Tack scenario

    Science.gov (United States)

    Jacobson, S. A.; Morbidelli, A.

    2014-01-01

    We present conclusions from a large number of N-body simulations of the giant impact phase of terrestrial planet formation. We focus on new results obtained from the recently proposed Grand Tack model, which couples the gas-driven migration of giant planets to the accretion of the terrestrial planets. The giant impact phase follows the oligarchic growth phase, which builds a bi-modal mass distribution within the disc of embryos and planetesimals. By varying the ratio of the total mass in the embryo population to the total mass in the planetesimal population and the mass of the individual embryos, we explore how different disc conditions control the final planets. The total mass ratio of embryos to planetesimals controls the timing of the last giant (Moon-forming) impact and its violence. The initial embryo mass sets the size of the lunar impactor and the growth rate of Mars. After comparing our simulated outcomes with the actual orbits of the terrestrial planets (angular momentum deficit, mass concentration) and taking into account independent geochemical constraints on the mass accreted by the Earth after the Moon-forming event and on the time scale for the growth of Mars, we conclude that the protoplanetary disc at the beginning of the giant impact phase must have had most of its mass in Mars-sized embryos and only a small fraction of the total disc mass in the planetesimal population. From this, we infer that the Moon-forming event occurred between approximately 60 and approximately 130 Myr after the formation of the first solids and was caused most likely by an object with a mass similar to that of Mars. PMID:25114304

  14. Late veneer and late accretion to the terrestrial planets

    Science.gov (United States)

    Brasser, R.; Mojzsis, S. J.; Werner, S. C.; Matsumura, S.; Ida, S.

    2016-12-01

    It is generally accepted that silicate-metal ('rocky') planet formation relies on coagulation from a mixture of sub-Mars sized planetary embryos and (smaller) planetesimals that dynamically emerge from the evolving circum-solar disc in the first few million years of our Solar System. Once the planets have, for the most part, assembled after a giant impact phase, they continue to be bombarded by a multitude of planetesimals left over from accretion. Here we place limits on the mass and evolution of these planetesimals based on constraints from the highly siderophile element (HSE) budget of the Moon. Outcomes from a combination of N-body and Monte Carlo simulations of planet formation lead us to four key conclusions about the nature of this early epoch. First, matching the terrestrial to lunar HSE ratio requires either that the late veneer on Earth consisted of a single lunar-size impactor striking the Earth before 4.45 Ga, or that it originated from the impact that created the Moon. An added complication is that analysis of lunar samples indicates the Moon does not preserve convincing evidence for a late veneer like Earth. Second, the expected chondritic veneer component on Mars is 0.06 weight percent. Third, the flux of terrestrial impactors must have been low (≲10-6 M⊕ Myr-1) to avoid wholesale melting of Earth's crust after 4.4 Ga, and to simultaneously match the number of observed lunar basins. This conclusion leads to an Hadean eon which is more clement than assumed previously. Last, after the terrestrial planets had fully formed, the mass in remnant planetesimals was ∼10-3 M⊕, lower by at least an order of magnitude than most previous models suggest. Our dynamically and geochemically self-consistent scenario requires that future N-body simulations of rocky planet formation either directly incorporate collisional grinding or rely on pebble accretion.

  15. Constraining the Properties of Small Stars and Small Planets Observed by K2

    Science.gov (United States)

    Dressing, Courtney D.; Newton, Elisabeth R.; Charbonneau, David; Schlieder, Josh; Hawaii/California/Arizona/Indiana K2 Follow-up Consortium, HARPS-N Consortium

    2016-01-01

    We are using the results of the NASA K2 mission (the second career of the Kepler spacecraft) to study how the frequency and architectures of planetary systems orbiting M dwarfs throughout the ecliptic plane compare to those of the early M dwarf planetary systems observed by Kepler. In a previous analysis of the Kepler data set, we found that planets orbiting early M dwarfs are common: we measured a cumulative planet occurrence rate of 2.45 +/- 0.22 planets per M dwarf with periods of 0.5-200 days and planet radii of 1-4 Earth radii. Within a conservative habitable zone based on the moist greenhouse inner limit and maximum greenhouse outer limit, we estimated an occurrence rate of 0.15 (+0.18/-0.06) Earth-size planets and 0.09 (+0.10/-0.04) super-Earths per M dwarf HZ. Applying these occurrence rates to the population of nearby stars and assuming that mid- and late-M dwarfs host planets at the same rate as early M dwarfs, we predicted that the nearest potentially habitable Earth-size planet likely orbits an M dwarf a mere 2.6 ± 0.4 pc away. We are now testing the assumption of equal planet occurrence rates for M dwarfs of all types by inspecting the population of planets detected by K2 and conducting follow-up observations of planet candidate host stars to identify false positives and better constrain system parameters. I will present the results of recent observing runs with SpeX on the IRTF to obtain near-infrared spectra of low-mass stars targeted by K2 and determine the radii, temperatures, and metallicities of our target stars using empirical relations. We gratefully acknowledge funding from the NASA XRP Program, the John Templeton Foundation, and the NASA Sagan Fellowship Program.

  16. Birth of an Earth-like Planet (Artist concept)

    Science.gov (United States)

    2007-01-01

    This artist's conception shows a binary-star, or two-star, system, called HD 113766, where astronomers suspect a rocky Earth-like planet is forming around one of the stars. At approximately 10 to 16 million years old, astronomers suspect this star is at just the right age for forming rocky planets. The system is located approximately 424 light-years away from Earth. The two yellow spots in the image represent the system's two stars. The brown ring of material circling closest to the central star depicts a huge belt of dusty material, more than 100 times as much as in our asteroid belt, or enough to build a Mars-size planet or larger. The rocky material in the belt represents the early stages of planet formation, when dust grains clump together to form rocks, and rocks collide to form even more massive rocky bodies called planetesimals. The belt is located in the middle of the system's terrestrial habitable zone, or the region around a star where liquid water could exist on any rocky planets that might form. Earth is located in the middle of our sun's terrestrial habitable zone. Using NASA's Spitzer Space Telescope, astronomers learned that the belt material in HD 113866 is more processed than the snowball-like stuff that makes up infant solar systems and comets, which contain pristine ingredients from the early solar system. However, it is not as processed as the stuff found in mature planets and asteroids. This means that the dust belt is made out of just the right mix of materials to be forming an Earth-like planet. It is composed mainly of rocky silicates and metal sulfides (like fool's gold), similar to the material found in lava flows. The white outer ring shows a concentration of icy dust also detected in the system. This material is at the equivalent position of the asteroid belt in our solar system, but only contains about one-sixth as much material as the inner ring. Astronomers say it is not clear from the Spitzer observations if anything is occurring in

  17. No planet for HD 166435

    OpenAIRE

    Queloz, D.; Henry, G. W.; Sivan, J. P.; Baliunas, S. L.; Beuzit, J. L.; Mayor, R. A. Donahue M.; Naef, D.; Perrier, C.; Udry, S.

    2001-01-01

    The G0V star HD166435 has been observed by the fiber-fed spectrograph ELODIE as one of the targets in the large extra-solar planet survey that we are conducting at the Observatory of Haute-Provence. We detected coherent, low-amplitude, radial-velocity variations with a period of 3.7987days, suggesting a possible close-in planetary companion. Subsequently, we initiated a series of high-precision photometric observations to search for possible planetary transits and an additional series of CaII...

  18. Planet earth a beginner's guide

    CERN Document Server

    Gribbin, John

    2012-01-01

    In this incredible expedition into the origins, workings, and evolution of our home planet, John Gribbin, bestselling author of In Search of Schrödinger's Cat, The Scientists, and In Search of the Multiverse, does what he does best: taking four and a half billion years of mind-boggling science and digging out the best bits. From the physics of Newton and the geology of Wegener, to the environmentalism of Lovelock, this is a must read for Earth's scientists and residents alike. Trained as an astrophysicist at Cambridge University, John Gribbin is currently Visiting Fellow in Astronomy at the University of Sussex, England.

  19. Selections from 2017: Atmosphere Around an Earth-Like Planet

    Science.gov (United States)

    Kohler, Susanna

    2017-12-01

    Editors note:In these last two weeks of 2017, well be looking at a few selections that we havent yet discussed on AAS Nova from among the most-downloaded paperspublished in AAS journals this year. The usual posting schedule will resume in January.Detection of the Atmosphere of the 1.6 M Exoplanet GJ 1132 bPublished March2017Main takeaway:An atmosphere was detected around the roughly Earth-size exoplanet GJ 1132 b using a telescope at the European Southern Observatory in Chile. A team of scientists led byJohn Southworth (Keele University) found features indicating the presence of an atmosphere in theobservationsof this 1.6-Earth-mass planet as it transits an M-dwarf host star. This is the lowest-mass planet with a detected atmosphere thus far.Why its interesting:M dwarfs are among the most common stars in our galaxy, and weve found manyEarth-sizeexoplanets in or near the habitable zones around M-dwarf hosts. But M dwarfs are also more magnetically active than stars like our Sun, suggesting that the planets in M-dwarfhabitable zones may not be able to support life due to stellar activity eroding their atmospheres. The detection of an atmosphere around GJ 1132 b suggests that some planets orbiting M dwarfsare able to retain their atmospheres which meansthat these planetsmay be an interesting place to search for life after all.How the atmosphere was detected:The measured planetary radius for GJ 1132 b as a function of the wavelength used to observe it. [Southworth et al. 2017]When measuring the radius of GJ 1132 b based on its transits, the authors noticed that the planet appeared to be largerwhen observed in some wavelengths than in others. This can beexplained if the planet has asurface radius of 1.4 Earth radii, overlaid by an atmosphere that extends out another few tenths of an Earth radius. The atmosphere, which may consist of water vapor or methane, is transparent to some wavelengths and absorbs others which is why the apparent size of the planet changes

  20. Mantles of terrestrial planets immediately following magma ocean solidification

    Science.gov (United States)

    Scheinberg, A. L.; Elkins-Tanton, L. T.; Zhong, S.; Parmentier, E.

    2010-12-01

    Energy of accretion in terrestrial planets is expected to create liquid silicate magma oceans. Their solidification processes create silicate differentiation and set the initial mantle structure for the planet. Solidification results in a compositionally unstable density profile, leading to cumulate Rayleigh-Taylor overturn in the early stages of planetary history. The pattern and timescale of overturn, in which cold, dense surface material sinks to the core mantle boundary, has implications for core dynamo production, volatile escape and fundamental differences between differently-sized bodies. Our fully spherical mantle models reaffirm previous work suggesting harmonic degree of overturn is dependent on viscosity contrast and layer thickness. We then explore the dependence of overturn morphology in the early mantles of Mars, Earth, Mercury and the Moon on these parameters and on the respective planets’ characteristics using a composition- and temperature-dependent viscosity model. Initial results indicate that fractional solidification and overturn in terrestrial planets always creates some radius range in which the mantle is azimuthally compositionally heterogeneous. After overturn, compositional stability in the mantle suppresses the onset of thermal convection; the broad conclusions of this work indicate that the earliest solid mantle of terrestrial planets is compositionally differentiated and stable.

  1. Extrasolar planets searches today and tomorrow

    CERN Multimedia

    2000-01-01

    So far the searches for extrasolar planets have found 40 planetary companions orbiting around nearby stars. In December 1999 a transit has been observed for one of them, providing the first independent confirmation of the reality of close-in planets as well as a measurement of its density. The techniques used to detect planets are limited and the detection threshold is biased but a first picture of the planet diversity and distribution emerges. Results of the search for extra-solar planets and their impacts on planetary formation will be reviewed. Future instruments are foreseen to detect Earth-like planets and possible signatures of organic activity. An overview of these future projects will be presented and more particularly the Darwin-IRSI mission studied by ESA for Horizon 2015.

  2. The naked planet Earth: Most essential pre-requisite for the origin and evolution of life

    OpenAIRE

    Maruyama, S; Ikoma, M.; Genda, H.; Hirose, K.; YOKOYAMA, T; M. Santosh

    2013-01-01

    Our blue planet Earth has long been regarded to carry full of nutrients for hosting life since the birth of the planet. Here we speculate the processes that led to the birth of early life on Earth and its aftermath, finally leading to the evolution of metazoans. We evaluate: (1) the source of nutrients, (2) the chemistry of primordial ocean, (3) the initial mass of ocean, and (4) the size of planet. Among the life-building nutrients, phosphorus and potassium play a key role. Only three types ...

  3. All for the Planet, the Planet for everyone!

    Science.gov (United States)

    Drndarski, Marina

    2014-05-01

    The Eco-Musketeers are unique voluntary group of students. They have been established in Belgrade, in Primary school 'Drinka Pavlović'. Since the founding in year 2000, Eco-Musketeers have been involved in peer and citizens education guided by motto: All for the planet, the planet for all! Main goals of this group are spreading and popularization of environmental approach as well as gaining knowledge through collaborative projects and research. A great number of students from other schools in Serbia have joined Eco-Musketeers in observations aiming to better understand the problem of global climate change. In the past several years Eco-Musketeers have also participated in many national and international projects related to the active citizenship and rising the awareness of the importance of biodiversity and environment for sustainable development of society. In this presentation we will show some of the main activities, eco-performances and actions of our organization related to the environment, biodiversity, conservation and recycling, such as: spring cleaning the streets of Belgrade, cleaning the Sava and the Danube river banks, removing insect moth pupae in the area of Lipovica forest near Belgrade. Also, Eco-Musketeers worked on education of employees of Coca-Cola HBC Serbia about energy efficiency. All the time, we have working on raising public awareness of the harmful effects of plastic bags on the environment, too. In order to draw attention on rare and endangered species in Serbia and around the globe, there were several performing street-plays about biodiversity and also the plays about the water ecological footprint. Eco-Musketeers also participated in international projects Greenwave-signs of spring (Fibonacci project), European Schools For A Living Planet (WWF Austria and Erste stiftung) and Eco Schools. The eco dream of Eco-Musketeers is to influence the Government of the Republic of Serbia to determine and declare a 'green habits week'. This should

  4. Space based microlensing planet searches

    Directory of Open Access Journals (Sweden)

    Tisserand Patrick

    2013-04-01

    Full Text Available The discovery of extra-solar planets is arguably the most exciting development in astrophysics during the past 15 years, rivalled only by the detection of dark energy. Two projects unite the communities of exoplanet scientists and cosmologists: the proposed ESA M class mission EUCLID and the large space mission WFIRST, top ranked by the Astronomy 2010 Decadal Survey report. The later states that: “Space-based microlensing is the optimal approach to providing a true statistical census of planetary systems in the Galaxy, over a range of likely semi-major axes”. They also add: “This census, combined with that made by the Kepler mission, will determine how common Earth-like planets are over a wide range of orbital parameters”. We will present a status report of the results obtained by microlensing on exoplanets and the new objectives of the next generation of ground based wide field imager networks. We will finally discuss the fantastic prospect offered by space based microlensing at the horizon 2020–2025.

  5. Characterizing Young Giant Planets with the Gemini Planet Imager: An Iterative Approach to Planet Characterization

    Science.gov (United States)

    Marley, Mark

    2015-01-01

    After discovery, the first task of exoplanet science is characterization. However experience has shown that the limited spectral range and resolution of most directly imaged exoplanet data requires an iterative approach to spectral modeling. Simple, brown dwarf-like models, must first be tested to ascertain if they are both adequate to reproduce the available data and consistent with additional constraints, including the age of the system and available limits on the planet's mass and luminosity, if any. When agreement is lacking, progressively more complex solutions must be considered, including non-solar composition, partial cloudiness, and disequilibrium chemistry. Such additional complexity must be balanced against an understanding of the limitations of the atmospheric models themselves. For example while great strides have been made in improving the opacities of important molecules, particularly NH3 and CH4, at high temperatures, much more work is needed to understand the opacity of atomic Na and K. The highly pressure broadened fundamental band of Na and K in the optical stretches into the near-infrared, strongly influencing the spectral shape of Y and J spectral bands. Discerning gravity and atmospheric composition is difficult, if not impossible, without both good atomic opacities as well as an excellent understanding of the relevant atmospheric chemistry. I will present examples of the iterative process of directly imaged exoplanet characterization as applied to both known and potentially newly discovered exoplanets with a focus on constraints provided by GPI spectra. If a new GPI planet is lacking, as a case study I will discuss HR 8799 c and d will explain why some solutions, such as spatially inhomogeneous cloudiness, introduce their own additional layers of complexity. If spectra of new planets from GPI are available I will explain the modeling process in the context of understanding these new worlds.

  6. Pathway to the galactic distribution of planets

    DEFF Research Database (Denmark)

    Novati, S. Calchi; Gould, A.; Udalski, A.

    2015-01-01

    distance estimates for each lens, with error bars that are small compared to the Sun's Galactocentric distance. The ensemble therefore yields a well-defined cumulative distribution of lens distances. In principle it is possible to compare this distribution against a set of planets detected in the same...... experiment in order to measure the Galactic distribution of planets. Since these Spitzer observations yielded only one planet, this is not yet possible in practice. However, it will become possible as larger samples are accumulated....

  7. TRANSITING PLANETS WITH LSST. II. PERIOD DETECTION OF PLANETS ORBITING 1 M{sub ⊙} HOSTS

    Energy Technology Data Exchange (ETDEWEB)

    Jacklin, Savannah [Department of Astrophysics and Planetary Science, Villanova University, Villanova, PA 19085 (United States); Lund, Michael B.; Stassun, Keivan G. [Department of Physics and Astronomy, Vanderbilt University, Nashville, TN 37235 (United States); Pepper, Joshua [Department of Physics, Lehigh University, Bethlehem, PA 18015 (United States)

    2015-07-15

    The Large Synoptic Survey Telescope (LSST) will photometrically monitor ∼10{sup 9} stars for 10 years. The resulting light curves can be used to detect transiting exoplanets. In particular, as demonstrated by Lund et al., LSST will probe stellar populations currently undersampled in most exoplanet transit surveys, including out to extragalactic distances. In this paper we test the efficiency of the box-fitting least-squares (BLS) algorithm for accurately recovering the periods of transiting exoplanets using simulated LSST data. We model planets with a range of radii orbiting a solar-mass star at a distance of 7 kpc, with orbital periods ranging from 0.5 to 20 days. We find that standard-cadence LSST observations will be able to reliably recover the periods of Hot Jupiters with periods shorter than ∼3 days; however, it will remain a challenge to confidently distinguish these transiting planets from false positives. At the same time, we find that the LSST deep-drilling cadence is extremely powerful: the BLS algorithm successfully recovers at least 30% of sub-Saturn-size exoplanets with orbital periods as long as 20 days, and a simple BLS power criterion robustly distinguishes ∼98% of these from photometric (i.e., statistical) false positives.

  8. Passing NASA's Planet Quest Baton from Kepler to TESS

    Science.gov (United States)

    Jenkins, J.

    Kepler vaulted into the heavens on March 7, 2009, initiating NASAs search for Earth- size planets orbiting Sun-like stars in the habitable zone, where liquid water could exist on a rocky planetary surface. In the 4 years since Kepler began science operations, a flood of photometric data on upwards of 190,000 stars of unprecedented precision and continuity has provoked a watershed of 134+ confirmed or validated planets, 3200+ planetary candidates (most sub-Neptune in size and many compara- ble to or smaller than Earth), and a resounding revolution in asteroseismology and astrophysics. The most recent discoveries include Kepler-62 with 5 planets total of which 2 are in the habitable zone with radii of 1.4 and 1.7 Re. The focus of the mission is shifting towards how to rapidly vet the 18,000+ threshold crossing events produced with each transiting planet search, and towards those studies that will allow us to understand what the data are saying about the prevalence of planets in the solar neighborhood and throughout the galaxy. This talk will provide an overview of the science results from the Kepler Mission and the work ahead to derive the frequency of Earth-size planets in the habitable zone of solar-like stars from the treasure trove of Kepler data. NASAs quest for exoplanets continues with the Transiting Exoplanet Survey Satel- lite (TESS) mission, slated for launch in May 2017 by NASAs Explorer Program. TESS will conduct an all-sky transit survey to identify the 1000 best small exoplanets in the solar neighborhood for follow up observations and characterization. TESSs targets will include all F, G, K dwarfs from +4 to +12 magnitude and all M dwarfs known within ˜200 light-years. 500,000 target stars will be observed over two years with ˜500 square degrees observed continuously for a year in each hemisphere in the James Webb Space Telescopes continuously viewable zones. Since the typical TESS target star is 5 magnitudes brighter than Kepler’s and 10 times

  9. Are Stellar Storms Bad News for M-Dwarf Planets?

    Science.gov (United States)

    Kohler, Susanna

    2016-09-01

    Coronal mass ejections (CMEs), enormous releases of energy from the Sun, can have significant space-weather implications for Earth. Do similar storms from smaller stars M dwarfs like V374 Peg, or the nearby Proxima Centauri mean bad news for the planets that these stars host?Volatile StarsDifference in habitable-zone sizes for different stellar types. [NASA]When plasma is released from the Sun in the form of a CME traveling toward Earth, these storms can be powerful enough to disrupt communications and navigational equipment, damage satellites, and cause blackouts even with our planetary magnetic field to protect us! How might planets in the habitable zone of M-dwarf stars fare against similar storms?The first danger for an M dwarfs planets is that the habitable zone lies much closer to the star: it can range from 0.03 to 0.4 AU (i.e., within Mercurys orbit). Being so close to the star definitely makes a planet in an M dwarfs habitable zone vulnerable to storms.Colors indicate the probability of CME impact, for different different stellar latitudes where the CME originated vs. orbital inclination of the planet, (a) without any deflection, and (b) taking into account the CME deflection by the stars magnetic field. Hanging out in an orbit aligned with the current sheet turns out to be a bad idea. [Adapted from Kay et al. 2016]What about the storms themselves? You might think that because M dwarfs are cooler stars, they would be quieter, releasing fewer CMEs with less energy. Surprisingly, the opposite is true: M dwarfs are significantly more active than solar-type stars, and the CMEs are typically ten times more massive than those released from the Sun. Impacts from these powerful outbursts could easily strip any existing planet atmosphere, making a planet much less likely to be habitable. To make matters worse, M dwarfs can remain magnetically active for billions of years: even a star like Proxima Centauri, which is nearly 5 billion years old, isstill relatively

  10. Numerical simulations for terrestrial planets formation

    Directory of Open Access Journals (Sweden)

    Ji J.

    2011-07-01

    Full Text Available We investigate the formation of terrestrial planets in the late stage of planetary formation using two-planet model. At that time, the protostar has formed for about 3 Myr and the gas disk has dissipated. In the model, the perturbations from Jupiter and Saturn are considered. We also consider variations of the mass of outer planet, and the initial eccentricities and inclinations of embryos and planetesimals. Our results show that, terrestrial planets are formed in 50 Myr, and the accretion rate is about 60%–80%. In each simulation, 3–4 terrestrial planets are formed inside “Jupiter” with masses of 0.15–3.6 M⊕. In the 0.5–4 AU, when the eccentricities of planetesimals are excited, planetesimals are able to accrete material from wide radial direction. The plenty of water material of the terrestrial planet in the Habitable Zone may be transferred from the farther places by this mechanism. Accretion may also happen a few times between two giant planets only if the outer planet has a moderate mass and the small terrestrial planet could survive at some resonances over time scale of 108 yr.

  11. Extrasolar planets formation, detection and dynamics

    CERN Document Server

    Dvorak, Rudolf

    2008-01-01

    This latest, up-to-date resource for research on extrasolar planets covers formation, dynamics, atmospheres and detection. After a look at the formation of giant planets, the book goes on to discuss the formation and dynamics of planets in resonances, planets in double stars, atmospheres and habitable zones, detection via spectra and transits, and the history and prospects of ESPs as well as satellite projects.Edited by a renowned expert in solar system dynamics with chapters written by the leading experts in the method described -- from the US and Europe -- this is an ideal textbook for g

  12. The interior structure of the giant planets

    Science.gov (United States)

    Zharkov, V. N.

    1991-12-01

    An overview of the principal ideas and data pertaining to the construction of models of the interior structure of Jupiter, Saturn, Uranus, and Neptune is presented. Topics discussed include: the concept of Jupiter and Saturn as planets with hydrogenic crusts; the theory of the figure of rotating planets in hydrostatic equilibrium; a gas-liquid dynamic model of the giant planets; analysis of observational data; abundances of elements and groups of cosmochemical substances; equations of state; and the role of Jupiter in the formation of the earth and the giant planets.

  13. Seven temperate terrestrial planets around the nearby ultracool dwarf star TRAPPIST-1.

    Science.gov (United States)

    Gillon, Michaël; Triaud, Amaury H M J; Demory, Brice-Olivier; Jehin, Emmanuël; Agol, Eric; Deck, Katherine M; Lederer, Susan M; de Wit, Julien; Burdanov, Artem; Ingalls, James G; Bolmont, Emeline; Leconte, Jeremy; Raymond, Sean N; Selsis, Franck; Turbet, Martin; Barkaoui, Khalid; Burgasser, Adam; Burleigh, Matthew R; Carey, Sean J; Chaushev, Aleksander; Copperwheat, Chris M; Delrez, Laetitia; Fernandes, Catarina S; Holdsworth, Daniel L; Kotze, Enrico J; Van Grootel, Valérie; Almleaky, Yaseen; Benkhaldoun, Zouhair; Magain, Pierre; Queloz, Didier

    2017-02-22

    One aim of modern astronomy is to detect temperate, Earth-like exoplanets that are well suited for atmospheric characterization. Recently, three Earth-sized planets were detected that transit (that is, pass in front of) a star with a mass just eight per cent that of the Sun, located 12 parsecs away. The transiting configuration of these planets, combined with the Jupiter-like size of their host star-named TRAPPIST-1-makes possible in-depth studies of their atmospheric properties with present-day and future astronomical facilities. Here we report the results of a photometric monitoring campaign of that star from the ground and space. Our observations reveal that at least seven planets with sizes and masses similar to those of Earth revolve around TRAPPIST-1. The six inner planets form a near-resonant chain, such that their orbital periods (1.51, 2.42, 4.04, 6.06, 9.1 and 12.35 days) are near-ratios of small integers. This architecture suggests that the planets formed farther from the star and migrated inwards. Moreover, the seven planets have equilibrium temperatures low enough to make possible the presence of liquid water on their surfaces.

  14. Seven temperate terrestrial planets around the nearby ultracool dwarf star TRAPPIST-1

    Science.gov (United States)

    Gillon, Michaël; Triaud, Amaury H. M. J.; Demory, Brice-Olivier; Jehin, Emmanuël; Agol, Eric; Deck, Katherine M.; Lederer, Susan M.; de Wit, Julien; Burdanov, Artem; Ingalls, James G.; Bolmont, Emeline; Leconte, Jeremy; Raymond, Sean N.; Selsis, Franck; Turbet, Martin; Barkaoui, Khalid; Burgasser, Adam; Burleigh, Matthew R.; Carey, Sean J.; Chaushev, Aleksander; Copperwheat, Chris M.; Delrez, Laetitia; Fernandes, Catarina S.; Holdsworth, Daniel L.; Kotze, Enrico J.; Van Grootel, Valérie; Almleaky, Yaseen; Benkhaldoun, Zouhair; Magain, Pierre; Queloz, Didier

    2017-01-01

    One focus of modern astronomy is to detect temperate terrestrial exoplanets well-suited for atmospheric characterisation. A milestone was recently achieved with the detection of three Earth-sized planets transiting (i.e. passing in front of) a star just 8% the mass of the Sun 12 parsecs away1. Indeed, the transiting configuration of these planets combined with the Jupiter-like size of their host star - named TRAPPIST-1 - makes possible in-depth studies of their atmospheric properties with current and future astronomical facilities1,2,3. Here we report the results of an intensive photometric monitoring campaign of that star from the ground and with the Spitzer Space Telescope. Our observations reveal that at least seven planets with sizes and masses similar to the Earth revolve around TRAPPIST-1. The six inner planets form a near-resonant chain such that their orbital periods (1.51, 2.42, 4.04, 6.06, 9.21, 12.35 days) are near ratios of small integers. This architecture suggests that the planets formed farther from the star and migrated inward4,5. The seven planets have equilibrium temperatures low enough to make possible liquid water on their surfaces6,7,8. PMID:28230125

  15. Atmospheric circulation modeling of super Earths and terrestrial extrasolar planets using the SPARC/MITgcm

    Science.gov (United States)

    Kataria, T.; Showman, A. P.; Haberle, R. M.; Marley, M. S.; Fortney, J. J.; Freedman, R. S.

    2013-12-01

    The field of exoplanets continues to be a booming field of research in astronomy and planetary science, with numerous ground-based (e.g., SuperWASP, HARPS-N and S) and space-based surveys (e.g., Kepler) that detect and characterize planets ranging from hot Jupiters, Jovian-sized planets orbiting less than 0.1 AU from their star, to super Earths and terrestrial exoplanets, planets that have masses equal to or less than 10 times that of Earth with a range of orbital distances. Atmospheric circulation modeling plays an important role in the characterization of these planets, helping to constrain observations that probe their atmospheres. These models have proven successful in understanding observations of transiting exoplanets (when the planet passes in front of the star along our line of sight) particularly when the planet is passing through secondary eclipse (when the planet's dayside is visible). In modeling super Earths and terrestrial exoplanets, we must consider not only planets with thick fluid envelopes, but also traditional terrestrial planets with solid surfaces and thinner atmospheres. To that end, we present results from studies investigating the atmospheric circulation of these classes of planets using the SPARC/MITgcm, a state-of-the-art model which couples the MIT General Circulation Model with a plane-parallel, two-stream, non-gray radiative transfer model. We will present results from two studies, the first focusing on the circulation of GJ 1214b, a super-Earth detected by the MEarth ground-based survey, and a second study which explores the circulation of terrestrial exoplanets orbiting M-dwarfs.

  16. Emergence of two types of terrestrial planet on solidification of magma ocean.

    Science.gov (United States)

    Hamano, Keiko; Abe, Yutaka; Genda, Hidenori

    2013-05-30

    Understanding the origins of the diversity in terrestrial planets is a fundamental goal in Earth and planetary sciences. In the Solar System, Venus has a similar size and bulk composition to those of Earth, but it lacks water. Because a richer variety of exoplanets is expected to be discovered, prediction of their atmospheres and surface environments requires a general framework for planetary evolution. Here we show that terrestrial planets can be divided into two distinct types on the basis of their evolutionary history during solidification from the initially hot molten state expected from the standard formation model. Even if, apart from their orbits, they were identical just after formation, the solidified planets can have different characteristics. A type I planet, which is formed beyond a certain critical distance from the host star, solidifies within several million years. If the planet acquires water during formation, most of this water is retained and forms the earliest oceans. In contrast, on a type II planet, which is formed inside the critical distance, a magma ocean can be sustained for longer, even with a larger initial amount of water. Its duration could be as long as 100 million years if the planet is formed together with a mass of water comparable to the total inventory of the modern Earth. Hydrodynamic escape desiccates type II planets during the slow solidification process. Although Earth is categorized as type I, it is not clear which type Venus is because its orbital distance is close to the critical distance. However, because the dryness of the surface and mantle predicted for type II planets is consistent with the characteristics of Venus, it may be representative of type II planets. Also, future observations may have a chance to detect not only terrestrial exoplanets covered with water ocean but also those covered with magma ocean around a young star.

  17. Planeta Ol'bersa: istoriya eshche ne zakonchena! %t Olbers' planet: the history continues indeed

    Science.gov (United States)

    Bagrov, A. V.

    Astronomical arguments provided by V. A. Bronshten and concerned with Olbers' hypothesis on the existence of another planet in the solar system long ago are too unsure. The usage of orbital parameter distributions among asteroids of the Main Belt implies too far extrapolation into the past. In the same manner the extrapolation of laboratory conditions to the scale of billion years can hardly be accepted as an argument against Olbers' conception. Practically all arguments against Olbers' planet are not trustworthy. So it is obvious that there is no generally accepted theory of the solar system origin and evolution. Here a new cosmogony scenario is brought forth. It is based upon the assumption that planets were formed when Sun was a cold protostar. The whole protoplanet nebula was rich with hydrogen, massive and viscous. The conditions produced low-velocity collisions between planetesimals, and reduced the characteristic times of planet growth. All planets had thick atmospheres, that provided thermal protection against internal heating of planet's core by short-living isotopes. The Phaeton planet had been almost entirely melted when it was destroyed in collision with an interstellar Moon-size body. Drops of this practically liquid planet scattered in all directions, but its inner parts remained near the initial orbit and formed the Main Asteroid Belt. Their multiple collisions caused surface craters rather than their breaking apart. Little drops that moved to the periphery of the protoplanet disk could attract frozen gases on the way and transformed into cometary cores that remain on distant orbits. About the same time the Sun became a star and its radiation heated the solar system and expelled hydrogen and other light gases from the atmospheres of Earth-like planets. This scenario should be checked by means of exact calculations yet. In any case the hypothesis of a planet destruction in the beginning of the solar system history seems to give better explanations of

  18. On the cavity of a debris disc carved by a giant planet

    Science.gov (United States)

    Regály, Zs.; Dencs, Z.; Moór, A.; Kovács, T.

    2018-01-01

    One possible explanation of the cavity in debris discs is the gravitational perturbation of an embedded giant planet. Planetesimals passing close to a massive body are dynamically stirred resulting in a cleared region known as the chaotic zone. Theory of overlapping mean-motion resonances predicts the width of this cavity. To test whether this cavity is identical to the chaotic zone, we investigate the formation of cavities by means of collisionless N-body simulations assuming a 1.25-10 Jupiter mass planet with eccentricities of 0-0.9. Synthetic images at millimetre wavelengths are calculated to determine the cavity properties by fitting an ellipse to 14 per cent contour level. Depending on the planetary eccentricity, epl, the elliptic cavity wall rotates as the planet orbits with the same (epl 0.2) period that of the planet. The cavity centre is offset from the star along the semimajor axis of the planet with a distance of d=0.1q^{-0.17}e_pl^{0.5} in units of cavity size towards the planet's orbital apocentre, where q is the planet-to-star mass ratio. Pericentre (apocentre) glow develops for epl 0.1), while both are present for 0.05 ≤ epl ≤ 0.1. Empirical formulae are derived for the sizes of the cavities: δacav = 2.35q0.36 and δ a_cav=7.87q^{0.37}e_pl^{0.38} for epl ≤ 0.05 and epl > 0.05, respectively. The cavity eccentricity, ecav, equals to that of the planet only for 0.3 ≤ epl ≤ 0.6. A new method based on Atacama Large Millimeter/submillimeter Array observations for estimating the orbital parameters and mass of the planet carving the cavity is also given.

  19. Post-main-sequence Evolution of Icy Minor Planets. III. Water Retention in Dwarf Planets and Exomoons and Implications for White Dwarf Pollution

    Science.gov (United States)

    Malamud, Uri; Perets, Hagai B.

    2017-11-01

    Studies suggest that the pollution of white dwarf (WD) atmospheres arises from the accretion of minor planets, but the exact properties of polluting material, and in particular the evidence for water in some cases are not yet understood. Several previous works studied the possibility of water surviving inside minor planets around evolving stars. However, they all focused on small, comet-sized to moonlet-sized minor planets, when the inferred mass inside the convection zones of He-dominated WDs could actually be compatible with much more massive minor planets. Here we explore for the first time, the water retention inside exoplanetary dwarf planets, or moderate-sized moons, with radii of the order of hundreds of kilometers. This paper concludes a series of papers that has now covered nearly the entire potential mass range of minor planets, in addition to the full mass range of their host stars. We find that water retention is (a) affected by the mass of the WD progenitor, and (b) it is on average at least 5%, irrespective of the assumed initial water composition, if it came from a single accretion event of an icy dwarf planet or moon. The latter prediction strengthens the possibility of habitability in WD planetary systems, and it may also be used in order to distinguish between pollution originating from multiple small accretion events and singular large accretion events. To conclude our work, we provide a code that calculates ice and water retention by interpolation and may be freely used as a service to the community.

  20. On the Unique Solution of Planet and Star Parameters from an Extrasolar Planet Transit Light Curve

    Science.gov (United States)

    Seager, S.; Mallén-Ornelas, G.

    A unique analytical solution of planet and star parameters can be derived from an extrasolar planet transit light curve under a number of assumptions. This analytical solution can be used to choose the best planet transit candidates for radial velocity follow-up measurements. In practice, high photometric precision (Ornelas (2003) for full details.

  1. Planet X - No dynamical evidence in the optical observations

    Science.gov (United States)

    Standish, E. M., Jr.

    1993-01-01

    It is shown that the alleged 'unexplained anomalies in the motion of Uranus' disappear when one properly accounts for the correct value of the mass of Neptune and properly adjusts the orbit of Uranus to the observational data. Also, it is shown that each of the 'irregularities in the measured positions of Neptune' has a complete explanation within the framework of the presently known solar system. As a check of certainty, an actual planetary ephemeris is integrated which well fits the observations of Uranus. Minor systematic errors do remain in the data, but they are very small; they are easily explained by a number of uncertainties in the observations themselves. There is now known to be a mass concentration of significant size in the outer solar system - 1992 QB1. In comparison to any of the major planets, though, this object is miniscule. For the meridian circle observations, there is still no evidence which requires or even indicates the existence of any planet-sized object; there remains no need to hypothesize the existence of a tenth planet in the solar system.

  2. Probing Terrestrial Planet Formation with Extreme Disk Variability

    Science.gov (United States)

    Su, Kate; Rieke, George; Gaspar, Andras; Jackson, Alan

    2016-08-01

    Spitzer has advanced our knowledge about the critical stages of terrestrial planet formation (and in some cases destruction) by discovering young stars orbited by 1.) silica dust emission close to their terrestrial zones indicative of the violent collisions, and 2.) variable disk emission arising from the aftermath of asteroid-size impacts. The variable emission provides a unique opportunity to learn about asteroid-sized bodies in young exoplanetary systems and to explore planetesimal collisions and their aftermaths during the era of terrestrial-planet-building. We propose continued study of debris disk variability, focused in two areas: (1) to provide continuous monitoring of systems where our existing program has discovered substantial variations indicative of major ongoing episodes of planetesimal impacts; and (2) to investigate intensively possible variations in the dust content of systems that show prominent crystalline emission features to establish a link between the two indicators of planet building. Together these objectives will prepare us for the JWST era, when we will again obtain mid-infrared spectra of these systems, and of both higher spectral resolution and signal to noise than has been possible previously. This program will extend the time-domain study of extreme debris disks as an important heritage of the Spitzer warm mission.

  3. Global stratigraphy. [of planet Mars

    Science.gov (United States)

    Tanaka, Kenneth L.; Scott, David H.; Greeley, Ronald

    1992-01-01

    Attention is given to recent major advances in the definition and documentation of Martian stratigraphy and geology. Mariner 9 provided the images for the first global geologic mapping program, resulting in the recognition of the major geologic processes that have operated on the planet, and in the definition of the three major chronostratigraphic divisions: the Noachian, Hesperian, and Amazonian Systems. Viking Orbiter images permitted the recognition of additional geologic units and the formal naming of many formations. Epochs are assigned absolute ages based on the densities of superposed craters and crater-flux models. Recommendations are made with regard to future areas of study, namely, crustal stratigraphy and structure, the highland-lowland boundary, the Tharsis Rise, Valles Marineris, channels and valley networks, and possible Martian oceans, lakes, and ponds.

  4. Chemistry of the outer planets

    Science.gov (United States)

    Scattergood, Thomas W.

    1992-05-01

    Various aspects were studied of past or present chemistry in the atmospheres of the outer planets and their satellites using lab simulations. Three areas were studied: (1) organic chemistry induced by kinetically hot hydrogen atoms in the region of Jupiter's atmosphere containing the ammonia cirrus clouds; (2) the conversion of NH3 into N2 by plasmas associated with entry of meteors and other objects into the atmosphere of early Titan; and (3) the synthesis of simple hydrocarbons and HCN by lightning in mixtures containing N2, CH4, and NH3 representing the atmospheres of Titan and the outer planets. The results showed that: (1) hot H2 atoms formed from the photodissociation of NH3 in Jupiter's atmosphere could account for some of the atmospheric chemistry in the ammonia cirrus cloud region; (2) the thermalization of hot H2 atoms in atmospheres predominated by molecular H is not as rapid as predicted by elastic collision theory; (3) the net quantum loss of NH3 in the presence of a 200 fold excess of H2 is 0.02, much higher than was expected from the amount of H2 present; (4) the conversion of NH3 into N2 in plasmas associated with infalling meteors is very efficient and rapid, and could account for most of the N2 present on Titan; (5) the yields of C2H2 and HCN from lightning induced chemistry in mixtures of CH4 and N2 is consistent with quenched thermodynamic models of the discharge core; and (6) photolysis induced by the UV light emitted by the gases in the hot plasmas may account for some, if not most, of the excess production of C2H6 and the more complex hydrocarbons.

  5. Kepler Planet Detection Mission: Introduction and First Results

    Science.gov (United States)

    Borucki, William; Koch, David; Basri, Gibor; Batalha, Natalie; Brown, Timothy; Lissauer, Jack J.; Morrison, David; Rowe, Jason; Bryson, Stephen T.; Dotson, Jessie; hide

    2010-01-01

    The Kepler Mission is designed to determine the frequency of Earth-size and rocky planets in and near the habitable zone (HZ) of solar-like stars. The HZ is defined to be the region of space where a rocky planet could maintain liquid water on its surface. Kepler is the 10th competitively-selected Discovery Mission and was launched on March 6, 2009. Since completing its commissioning, Kepler has observed over 156,000 stars simultaneously and near continuously to search for planets that periodically pass in front of their host star (transit). The photometric precision is approximately 23 ppm for 50% of the 12th magnitude dwarf stars for an integration period of 6.5 hours. During the first 3 months of operation the photometer detected transit-like signatures from more than 200 stars. Careful examination shows that many of these events are false-positives such as small stars orbiting large stars or blends of target stars with eclipsing binary stars. Ground-based follow-up observations confirm the discovery of five new exoplanets with sizes between 0.37 andl.6 Jupiter radii (R(sub J)) and orbital periods ranging from 3.2 to 4.9 days. Ground-based observations with the Keck 1, Hobby-Ebberly, Hale, WIYN, MMT, Tillinghast, Shane, and Nordic Optical Telescopes are used to vet the planetary candidates and measure the masses of the putative planets. Observations of occultations and phase variations of hot, short-period planets such as HT-P-7b provide a probe of atmospheric properties. Asteroseismic analysis already shows the presence of p-mode oscillations in several stars. Such observations will be used to measure the mean stellar density and infer the stellar size and age. For stars too dim to permit asteroseismology, observations of the centroid motion of target stars will be used to measure the parallax and be combined with photometric measurements to estimate stellar sizes. Four open clusters are being observed to determine stellar rotation rates as a function of age and

  6. Just how much do the planets affect the tides?

    Science.gov (United States)

    Cregg, P. J.

    2017-09-01

    The influence of the planets, and planetary alignment on the Earth’s tides is addressed. Starting from Newton’s law of gravitation, the tidal influence of any celestial body is expressed in terms of its apparent size and its density. From this, planetary alignment can be seen to contribute at most tenths of a millimetre to a tide and so is unlikely to be a significant contributor to exceptional tidal events. The likely causes of extreme tidal events are outlined: when the Sun and Moon are each closest to Earth, equinox, and weather—in particular extreme air pressure, rainfall, and wind. We conclude with the long-term influence of the planets on the Earth’s orbit and thus on the Sun’s tidal effect (with timescales of the order of 100 000 years), and planetary influence on the Moon’s orbit.

  7. Planet map generation by tetrahedral subdivision

    DEFF Research Database (Denmark)

    Mogensen, Torben Ægidius

    2010-01-01

    We present a method for generating pseudo-random, zoomable planet maps for games and art.  The method is based on spatial subdivision using tetrahedrons.  This ensures planet maps without discontinuities caused by mapping a flat map onto a sphere. We compare the method to other map...

  8. Detecting planets around stars in nearby galaxies

    NARCIS (Netherlands)

    Covone, G; de Ritis, R; Dominik, M; Marino, AA

    The only way to detect planets around stars at distances greater than or similar to several kpc is by (photometric or astrometric) microlensing (mu L) observations. In this paper, we show that the capability of photometric mu L extends to the detection of signals caused by planets around stars in

  9. Gravitational Microlensing of Earth-mass Planets

    DEFF Research Database (Denmark)

    Harpsøe, Kennet Bomann West

    It was only 17 years ago that the first planet outside of our own solar system was detected in the form of 51 Pegasi b. This planet is unlike anything in our own solar system. In fact, this planet was the first representative of a class of planets later known as “hot Jupiters”– gas giants......, i.e. it is much easier to detect high mass planets in close orbits. With these two methods it is hard to detect planets in an exo-solar system with a structure similar to our own solar system; specifically, it is hard to detect Earth-like planets in Earth-like orbits. It is presently unknown how...... common such planets are in our galaxy. There are a few other known methods for detecting exoplanets which have very different bias patterns. This thesis has been divided into two parts, treating two of these other methods. Part I is dedicated to the method of gravitational microlensing, a method...

  10. Journey to a Star Rich with Planets

    Science.gov (United States)

    2007-01-01

    [figure removed for brevity, see original site] Click on the image for movie of Journey to a Star Rich with Planets This artist's animation takes us on a journey to 55 Cancri, a star with a family of five known planets - the most planets discovered so far around a star besides our own. The animation begins on Earth, with a view of the night sky and 55 Cancri (flashing dot), located 41 light-years away in the constellation Cancer. It then zooms through our solar system, passing our asteroids and planets, until finally arriving at the outskirts of 55 Cancri. The first planet to appear is the farthest out from the star -- a giant planet, probably made of gas, with a mass four times that of Jupiter. This planet orbits its star every 14 years, similar to Jupiter's 11.9-year orbit. As the movie continues, the three inner planets are shown, the closest of which is about 10 to 13 times the mass of Earth with an orbital period of less than three days. Zooming out, the animation highlights the newest member of the 55 Cancri family - a massive planet, likely made of gas, water and rock, about 45 times the mass of Earth and orbiting the star every 260 days. This planet is the fourth out from the star, and lies in the system's habitable zone (green). A habitable zone is the place around a star where liquid water would persist. Though the newest planet probably has a thick gaseous envelope, astronomers speculate that it could have one or more moons. In our own solar system, moons are common, so it seems likely that they also orbit planets in other solar systems. If such moons do exist, and if they are as large as Mars or Earth, astronomers speculate that they would retain atmospheres and surface liquid water that might make interesting environments for the development of life. The animation ends with a comparison between 55 Cancri and our solar system. The colors of the illustrated planets were chosen to resemble those of our own solar system. Astronomers do not know what the

  11. Geophysical and atmospheric evolution of habitable planets.

    Science.gov (United States)

    Lammer, Helmut; Selsis, Frank; Chassefière, Eric; Breuer, Doris; Griessmeier, Jean-Mathias; Kulikov, Yuri N; Erkaev, Nikolai V; Khodachenko, Maxim L; Biernat, Helfried K; Leblanc, Francois; Kallio, Esa; Lundin, Richard; Westall, Frances; Bauer, Siegfried J; Beichman, Charles; Danchi, William; Eiroa, Carlos; Fridlund, Malcolm; Gröller, Hannes; Hanslmeier, Arnold; Hausleitner, Walter; Henning, Thomas; Herbst, Tom; Kaltenegger, Lisa; Léger, Alain; Leitzinger, Martin; Lichtenegger, Herbert I M; Liseau, René; Lunine, Jonathan; Motschmann, Uwe; Odert, Petra; Paresce, Francesco; Parnell, John; Penny, Alan; Quirrenbach, Andreas; Rauer, Heike; Röttgering, Huub; Schneider, Jean; Spohn, Tilman; Stadelmann, Anja; Stangl, Günter; Stam, Daphne; Tinetti, Giovanna; White, Glenn J

    2010-01-01

    The evolution of Earth-like habitable planets is a complex process that depends on the geodynamical and geophysical environments. In particular, it is necessary that plate tectonics remain active over billions of years. These geophysically active environments are strongly coupled to a planet's host star parameters, such as mass, luminosity and activity, orbit location of the habitable zone, and the planet's initial water inventory. Depending on the host star's radiation and particle flux evolution, the composition in the thermosphere, and the availability of an active magnetic dynamo, the atmospheres of Earth-like planets within their habitable zones are differently affected due to thermal and nonthermal escape processes. For some planets, strong atmospheric escape could even effect the stability of the atmosphere.

  12. Reflected eclipses on circumbinary planets

    Directory of Open Access Journals (Sweden)

    Deeg H.J.

    2011-02-01

    Full Text Available A photometric method to detect planets orbiting around shortperiodic binary stars is presented. It is based on the detection of eclipse-signatures in the reflected light of circumbinary planets. Amplitudes of such ’reflected eclipses’ will depend on the orbital configurations of binary and planet relative to the observer. Reflected eclipses will occur with a period that is distinct from the binary eclipses, and their timing will also be modified by variations in the light-travel time of the eclipse signal. For the sample of eclipsing binaries found by the Kepler mission, reflected eclipses from close circumbinary planets may be detectable around at least several dozen binaries. A thorough detection effort of such reflected eclipses may then detect the inner planets present, or give solid limits to their abundance.

  13. Long-Term Stability of Planets in the Alpha Centauri System

    Science.gov (United States)

    Lissauer, Jack; Quarles, Billy

    2015-01-01

    The alpha Centauri system is billions of years old, so planets are only expected to be found in regions where their orbits are long-lived. We evaluate the extent of the regions within the alpha Centauri AB star system where small planets are able to orbit for billion-year timescales, and we map the positions in the sky plane where planets on stable orbits about either stellar component may appear. We confirm the qualitative results of Wiegert & Holman (Astron. J. 113, 1445, 1997) regarding the approximate size of the regions of stable orbits of a single planet, which are larger for retrograde orbits relative to the binary than for pro-grade orbits. Additionally, we find that mean motion resonances with the binary orbit leave an imprint on the limits of orbital stability, and the effects of the Lidov-Kozai mechanism are also readily apparent. Overall, orbits of a single planet in the habitable zones near the plane of the binary are stable, whereas high-inclination orbits are short-lived. However, even well within regions where single planets are stable, multiple planet systems must be significantly more widely-spaced than they need to be around an isolated star in order to be long-lived.

  14. The Kepler Mission: A Mission to Determine the Frequency of Inner Planets Neat the Habitable Zone of a Wide Range of Stars

    Science.gov (United States)

    Borucki, W. J.; Koch, D. G.; Dunham, E. W.; Jenkins, J. M.; Young, Richard E. (Technical Monitor)

    1997-01-01

    The surprising discovery of giant planets in inner orbits around solar-like stars has brought into question our understanding of the development and evolution of planetary systems, including our solar system. To make further progress, it is critical to detect and obtain data on the frequency and characteristics of Earth-class planets. The Kepler Mission is designed to be a quick, low-cost approach to accomplish that objective. Transits by Earth-class planets produce a fractional change in stellar brightness of 5 x 10(exp -5) to 40 x 10(exp -5) lasting for 4 to 16 hours, From the period and depth of the transits, the orbit and size of the planets can be calculated. The proposed instrument is a one-meter aperture photometer with a 12 deg field-of-view (FOV). To obtain the required precision and to avoid interruptions caused by day-night and seasonal cycles, the photometer will be launched into a heliocentric orbit. It will continuously and simultaneously monitor the flux from 80,000 dwarf stars brighter than 14th magnitude in the Cygnus constellation. The mission tests the hypothesis that the formation of most stars produces Earth-class planets in inner orbits. Based on this assumption and the recent observations that 2% of the stars have giant planets in inner orbits, several types of results are expected from the mission: 1. From transits of Earth-class planets, about 480 planet detections and 60 cases where two or more planets are found in the same system. 2. From transits of giant planets, about 160 detections of inner-orbit planets and 24 detections of outer-orbit planets. 3. From the phase modulation of the reflected light from giant planets, about 1400 planet detections with periods less than a week, albedos for 160 of these giant planets, and densities for seven planets.

  15. The Kepler Mission: A Mission to Determine the Frequency of Inner Planets Near the Habitable Zone of a Wide Range of Stars

    Science.gov (United States)

    Borucki, W. J.; Koch, D. G.; Dunham, E. W.; Jenkins, J. M.

    1997-01-01

    The surprising discovery of giant planets in inner orbits around solar-like stars has brought into question our understanding of the development and evolution of planetary systems, including our solar system. To make further progress, it is critical to detect and obtain data on the frequency and characteristics of Earth-class planets. The Kepler Mission is designed to be a quick, low-cost approach to accomplish that objective. Transits by Earth-class planets produce a fractional change. in stellar brightness of 5 x 10(exp -5) to 40 x 10(exp -5) lasting for 4 to 16 hours. From the period and depth of the transits, the orbit and size of the planets can be calculated. The proposed instrument is a one-meter aperture photometer with a 12 deg. field-of-view (FOV). To obtain the required precision and to avoid interruptions caused by day-night and seasonal cycles, the photometer will be launched into a heliocentric orbit. It will continuously and simultaneously monitor the flux from 80,000 dwarf stars brighter than 14th magnitude in the Cygnus constellation. The mission tests the hypothesis that the formation of most stars produces Earth-class planets in inner orbits. Based on this assumption and the recent observations that 2% of the stars have giant planets in inner orbits, several types of results are expected from the mission: 1. From transits of Earth-class planets, about 480 planet detections and 60 cases where two or more planets are found in the same system. 2. From transits of giant planets, about 160 detections of inner-orbit planets and 24 detections of outer-orbit planets. 3. From the phase modulation of the reflected light from giant planets, about 1400 planet detections with periods less than a week, albedos for 160 of these giant planets, and densities for seven planets.

  16. Comprehensive wide-band magnitudes and albedos for the planets, with applications to exo-planets and Planet Nine

    Science.gov (United States)

    Mallama, Anthony; Krobusek, Bruce; Pavlov, Hristo

    2017-01-01

    Complete sets of reference magnitudes in all 7 Johnson-Cousins bands (U, B, V, R, I, RC and IC) and the 5 principal Sloan bands (u', g', r', i', and z') are presented for the 8 planets. These data are accompanied by illumination phase functions and other formulas which characterize the instantaneous brightness of the planets. The main source of Johnson-Cousins magnitudes is a series of individualized photometric studies reported in recent years. Gaps in that dataset were filled with magnitudes synthesized in this study from published spectrophotometry. The planetary Sloan magnitudes, which are established here for the first time, are an average of newly recorded Sloan filter photometry, synthetic magnitudes and values transformed from the Johnson-Cousins system. Geometric albedos derived from these two sets of magnitudes are consistent within each photometric system and between the systems for all planets and in all bands. This consistency validates the albedos themselves as well as the magnitudes from which they were derived. In addition, a quantity termed the delta stellar magnitude is introduced to indicate the difference between the magnitude of a planet and that of its parent star. A table of these delta values for exo-planets possessing a range of physical characteristics is presented. The delta magnitudes are for phase angle 90° where a planet is near the greatest apparent separation from its star. This quantity may be useful in exo-planet detection and observation strategies when an estimate of the signal-to-noise ratio is needed. Likewise, the phase curves presented in this paper can be used for characterizing exo-planets. Finally, magnitudes for the proposed Planet Nine are estimated, and we note that P9 may be especially faint at red and near-IR wavelengths.

  17. Is There a Temperature Limit in Planet Formation at 1000 K?

    Science.gov (United States)

    Demirci, Tunahan; Teiser, Jens; Steinpilz, Tobias; Landers, Joachim; Salamon, Soma; Wende, Heiko; Wurm, Gerhard

    2017-09-01

    Dust drifting inward in protoplanetary disks is subject to increasing temperatures. In laboratory experiments, we tempered basaltic dust between 873 K and 1273 K and find that the dust grains change in size and composition. These modifications influence the outcome of self-consistent low speed aggregation experiments showing a transition temperature of 1000 K. Dust tempered at lower temperatures grows to a maximum aggregate size of 2.02 ± 0.06 mm, which is 1.49 ± 0.08 times the value for dust tempered at higher temperatures. A similar size ratio of 1.75 ± 0.16 results for a different set of collision velocities. This transition temperature is in agreement with orbit temperatures deduced for observed extrasolar planets. Most terrestrial planets are observed at positions equivalent to less than 1000 K. Dust aggregation on the millimeter-scale at elevated temperatures might therefore be a key factor for terrestrial planet formation.

  18. Eating on an interconnected planet

    Science.gov (United States)

    MacDonald, Graham K.

    2013-06-01

    (Carr et al 2012). A central finding of Fader et al 's study is that domestic crop production could theoretically replace imports and allow food self-sufficiency in many countries. Embracing this potential could lessen the need to increase imports as populations grow. Yet, in their extreme scenario—assuming no yield improvements, no agricultural expansion and high population growth rates—roughly 51% of the global population would be import dependent by 2050. While improbable, this case raises the question of how such a spike in crop demands might ricochet across producing countries. Exporters could alter their production and export rates in response to various internal or external drivers, such as land-use policies, concerns over grain stocks, or climate change impacts (Hertel et al 2010, Lambin and Meyfroidt 2011, Headey 2011). Suweis et al (2013) suggest that water-rich nations are unlikely to maintain their current crop export rates amidst global change, questioning the persistence of global food trade relationships in the absence of mitigative actions. The uneven role of a relatively small number of nations to the food security of many is apparent when considering the origins of key crops imported by countries that Fader et al estimate have already crossed a resource boundary limiting food self-sufficiency (figure 1). Figure 1. Figure 1. The origins of key crops (maize, milled/paddy rice, soybean, and wheat) imported by 49 countries that have exceeded a land or water constraint boundary currently limiting food self-sufficiency. The map of countries exceeding at least one boundary circa 2000, shaded in black, is based on figure 1(B) in Fader et al (2013). The size of the lines indicate the relative quantity of kilocalories imported, calculated using FAO (2013) import matrices and crop kilocalorie contents (FAO 2001) averaged for the period 2000-2010. Internal trade among countries that had exceeded a land or water boundary totaled ~6%. Small island nations and 11

  19. Does the Galactic Bulge Have Fewer Planets?

    Science.gov (United States)

    Kohler, Susanna

    2016-12-01

    The Milky Ways dense central bulge is a very different environment than the surrounding galactic disk in which we live. Do the differences affect the ability of planets to form in the bulge?Exploring Galactic PlanetsSchematic illustrating how gravitational microlensing by an extrasolar planet works. [NASA]Planet formation is a complex process with many aspects that we dont yet understand. Do environmental properties like host star metallicity, the density of nearby stars, or the intensity of the ambient radiation field affect the ability of planets to form? To answer these questions, we will ultimately need to search for planets around stars in a large variety of different environments in our galaxy.One way to detect recently formed, distant planets is by gravitational microlensing. In this process, light from a distant source star is bent by a lens star that is briefly located between us and the source. As the Earth moves, this momentary alignment causes a blip in the sources light curve that we can detect and planets hosted by the lens star can cause an additional observable bump.Artists impression of the Milky Way galaxy. The central bulge is much denserthan the surroundingdisk. [ESO/NASA/JPL-Caltech/M. Kornmesser/R. Hurt]Relative AbundancesMost source stars reside in the galactic bulge, so microlensing events can probe planetary systems at any distance between the Earth and the galactic bulge. This means that planet detections from microlensing could potentially be used to measure the relative abundances of exoplanets in different parts of our galaxy.A team of scientists led by Matthew Penny, a Sagan postdoctoral fellow at Ohio State University, set out to do just that. The group considered a sample of 31 exoplanetary systems detected by microlensing and asked the following question: are the planet abundances in the galactic bulge and the galactic disk the same?A Paucity of PlanetsTo answer this question, Penny and collaborators derived the expected

  20. No Snowball on Habitable Tidally Locked Planets

    Science.gov (United States)

    Checlair, Jade; Menou, Kristen; Abbot, Dorian S.

    2017-08-01

    The TRAPPIST-1, Proxima Centauri, and LHS 1140 systems are the most exciting prospects for future follow-up observations of potentially inhabited planets. All of the planets orbit nearby M-stars and are likely tidally locked in 1:1 spin-orbit states, which motivates the consideration of the effects that tidal locking might have on planetary habitability. On Earth, periods of global glaciation (snowballs) may have been essential for habitability and remote signs of life (biosignatures) because they are correlated with increases in the complexity of life and in the atmospheric oxygen concentration. In this paper, we investigate the snowball bifurcation (sudden onset of global glaciation) on tidally locked planets using both an energy balance model and an intermediate-complexity global climate model. We show that tidally locked planets are unlikely to exhibit a snowball bifurcation as a direct result of the spatial pattern of insolation they receive. Instead, they will smoothly transition from partial to complete ice coverage and back. A major implication of this work is that tidally locked planets with an active carbon cycle should not be found in a snowball state. Moreover, this work implies that tidally locked planets near the outer edge of the habitable zone with low CO2 outgassing fluxes will equilibrate with a small unglaciated substellar region rather than cycling between warm and snowball states. More work is needed to determine how the lack of a snowball bifurcation might affect the development of life on a tidally locked planet.

  1. Exploring the planets a memoir

    CERN Document Server

    Taylor, Fred

    2016-01-01

    This book is an informal, semi-autobiographical history, from the particular viewpoint of someone who was involved, of the exploration of the Solar System using spacecraft. The author is a Northumbrian, a Liverpudlian, a Californian, and an Oxford Don with half a century of experience of devising and deploying experiments to study the Earth and the planets, moons, and small bodies of the Solar System. Along with memories and anecdotes about his experiences as a participant in the space programme from its earliest days to the present, he describes in non-technical terms the science goals that drove the projects as well as the politics, pressures, and problems that had to be addressed and overcome on the way. The theme is the scientific intent of these ambitious voyages of discovery, and the joys and hardships of working to see them achieved. The narrative gives a first-hand account of things like how Earth satellites came to revolutionize weather forecasting, starting in the 1960s; how observations from space ...

  2. Used planet: a global history.

    Science.gov (United States)

    Ellis, Erle C; Kaplan, Jed O; Fuller, Dorian Q; Vavrus, Steve; Klein Goldewijk, Kees; Verburg, Peter H

    2013-05-14

    Human use of land has transformed ecosystem pattern and process across most of the terrestrial biosphere, a global change often described as historically recent and potentially catastrophic for both humanity and the biosphere. Interdisciplinary paleoecological, archaeological, and historical studies challenge this view, indicating that land use has been extensive and sustained for millennia in some regions and that recent trends may represent as much a recovery as an acceleration. Here we synthesize recent scientific evidence and theory on the emergence, history, and future of land use as a process transforming the Earth System and use this to explain why relatively small human populations likely caused widespread and profound ecological changes more than 3,000 y ago, whereas the largest and wealthiest human populations in history are using less arable land per person every decade. Contrasting two spatially explicit global reconstructions of land-use history shows that reconstructions incorporating adaptive changes in land-use systems over time, including land-use intensification, offer a more spatially detailed and plausible assessment of our planet's history, with a biosphere and perhaps even climate long ago affected by humans. Although land-use processes are now shifting rapidly from historical patterns in both type and scale, integrative global land-use models that incorporate dynamic adaptations in human-environment relationships help to advance our understanding of both past and future land-use changes, including their sustainability and potential global effects.

  3. The Evaporation Valley in the Kepler Planets

    Science.gov (United States)

    Owen, James E.; Wu, Yanqin

    2017-09-01

    A new piece of evidence supporting the photoevaporation-driven evolution model for low-mass, close-in exoplanets was recently presented by the California-Kepler Survey. The radius distribution of the Kepler planets is shown to be bimodal, with a “valley” separating two peaks at 1.3 and 2.6 R ⊕. Such an “evaporation valley” had been predicted by numerical models previously. Here, we develop a minimal model to demonstrate that this valley results from the following fact: the timescale for envelope erosion is the longest for those planets with hydrogen/helium-rich envelopes that, while only a few percent in weight, double its radius. The timescale falls for envelopes lighter than this because the planet’s radius remains largely constant for tenuous envelopes. The timescale also drops for heavier envelopes because the planet swells up faster than the addition of envelope mass. Photoevaporation therefore herds planets into either bare cores (˜1.3 R ⊕), or those with double the core’s radius (˜2.6 R ⊕). This process mostly occurs during the first 100 Myr when the stars’ high-energy fluxes are high and nearly constant. The observed radius distribution further requires the Kepler planets to be clustered around 3 M ⊕ in mass, born with H/He envelopes more than a few percent in mass, and that their cores are similar to the Earth in composition. Such envelopes must have been accreted before the dispersal of the gas disks, while the core composition indicates formation inside the ice line. Lastly, the photoevaporation model fails to account for bare planets beyond ˜30-60 days; if these planets are abundant, they may point to a significant second channel for planet formation, resembling the solar system terrestrial planets.

  4. Discovery of a warm, dusty giant planet around HIP 65426

    Science.gov (United States)

    Chauvin, G.; Desidera, S.; Lagrange, A.-M.; Vigan, A.; Gratton, R.; Langlois, M.; Bonnefoy, M.; Beuzit, J.-L.; Feldt, M.; Mouillet, D.; Meyer, M.; Cheetham, A.; Biller, B.; Boccaletti, A.; D'Orazi, V.; Galicher, R.; Hagelberg, J.; Maire, A.-L.; Mesa, D.; Olofsson, J.; Samland, M.; Schmidt, T. O. B.; Sissa, E.; Bonavita, M.; Charnay, B.; Cudel, M.; Daemgen, S.; Delorme, P.; Janin-Potiron, P.; Janson, M.; Keppler, M.; Le Coroller, H.; Ligi, R.; Marleau, G. D.; Messina, S.; Mollière, P.; Mordasini, C.; Müller, A.; Peretti, S.; Perrot, C.; Rodet, L.; Rouan, D.; Zurlo, A.; Dominik, C.; Henning, T.; Menard, F.; Schmid, H.-M.; Turatto, M.; Udry, S.; Vakili, F.; Abe, L.; Antichi, J.; Baruffolo, A.; Baudoz, P.; Baudrand, J.; Blanchard, P.; Bazzon, A.; Buey, T.; Carbillet, M.; Carle, M.; Charton, J.; Cascone, E.; Claudi, R.; Costille, A.; Deboulbe, A.; De Caprio, V.; Dohlen, K.; Fantinel, D.; Feautrier, P.; Fusco, T.; Gigan, P.; Giro, E.; Gisler, D.; Gluck, L.; Hubin, N.; Hugot, E.; Jaquet, M.; Kasper, M.; Madec, F.; Magnard, Y.; Martinez, P.; Maurel, D.; Le Mignant, D.; Möller-Nilsson, O.; Llored, M.; Moulin, T.; Origné, A.; Pavlov, A.; Perret, D.; Petit, C.; Pragt, J.; Puget, P.; Rabou, P.; Ramos, J.; Rigal, R.; Rochat, S.; Roelfsema, R.; Rousset, G.; Roux, A.; Salasnich, B.; Sauvage, J.-F.; Sevin, A.; Soenke, C.; Stadler, E.; Suarez, M.; Weber, L.; Wildi, F.; Antoniucci, S.; Augereau, J.-C.; Baudino, J.-L.; Brandner, W.; Engler, N.; Girard, J.; Gry, C.; Kral, Q.; Kopytova, T.; Lagadec, E.; Milli, J.; Moutou, C.; Schlieder, J.; Szulágyi, J.; Thalmann, C.; Wahhaj, Z.

    2017-09-01

    Aims: The SHINE program is a high-contrast near-infrared survey of 600 young, nearby stars aimed at searching for and characterizing new planetary systems using VLT/SPHERE's unprecedented high-contrast and high-angular-resolution imaging capabilities. It is also intended to place statistical constraints on the rate, mass and orbital distributions of the giant planet population at large orbits as a function of the stellar host mass and age to test planet-formation theories. Methods: We used the IRDIS dual-band imager and the IFS integral field spectrograph of SPHERE to acquire high-contrast coronagraphic differential near-infrared images and spectra of the young A2 star HIP 65426. It is a member of the 17 Myr old Lower Centaurus-Crux association. Results: At a separation of 830 mas (92 au projected) from the star, we detect a faint red companion. Multi-epoch observations confirm that it shares common proper motion with HIP 65426. Spectro-photometric measurements extracted with IFS and IRDIS between 0.95 and 2.2 μm indicate a warm, dusty atmosphere characteristic of young low-surface-gravity L5-L7 dwarfs. Hot-start evolutionary models predict a luminosity consistent with a 6-12 MJup, Teff = 1300-1600 K and R = 1.5 ± 0.1 RJup giant planet. Finally, the comparison with Exo-REM and PHOENIX BT-Settl synthetic atmosphere models gives consistent effective temperatures but with slightly higher surface gravity solutions of log (g) = 4.0-5.0 with smaller radii (1.0-1.3 RJup). Conclusions: Given its physical and spectral properties, HIP 65426 b occupies a rather unique placement in terms of age, mass, and spectral-type among the currently known imaged planets. It represents a particularly interesting case to study the presence of clouds as a function of particle size, composition, and location in the atmosphere, to search for signatures of non-equilibrium chemistry, and finally to test the theory of planet formation and evolution. Based on observations collected at La Silla

  5. Extrasolar planets : - From gaseous giant planets to rocky planets. - Steps towards the detection of life biomarkers.

    CERN Multimedia

    CERN. Geneva

    2017-01-01

    Today, great efforts are made to detect Earth-mass rocky planets in the so-called habitable zone of their host stars. What are the difficulties, the instrumental projects  and the already detected interesting systems ?

  6. Limits On Undetected Planets in the Six Transiting Planets Kepler-11 System

    Science.gov (United States)

    Lissauer, Jack

    2017-01-01

    The Kepler-11 has five inner planets ranging from approx. 2 - 1 times as massive Earth in a tightly-packed configuration, with orbital periods between 10 and 47 days. A sixth planet, Kepler-11 g, with a period of118 days, is also observed. The spacing between planets Kepler-11 f and Kepler-11 g is wide enough to allow room for a planet to orbit stably between them. We compare six and seven planet fits to measured transit timing variations (TTVs) of the six known planets. We find that in most cases an additional planet between Kepler-11 f and Kepler-11 g degrades rather than enhances the fit to the TTV data, and where the fit is improved, the improvement provides no significant evidence of a planet between Kepler-11 f and Kepler-11 g. This implies that any planet in this region must be low in mass. We also provide constraints on undiscovered planets orbiting exterior to Kepler-11 g. representations will be described.

  7. Radio emission of the sun and planets

    CERN Document Server

    Zheleznyakov, V V

    1970-01-01

    International Series of Monographs in Natural Philosophy, Volume 25: Radio Emission of the Sun and Planets presents the origin of the radio emission of the planets. This book examines the outstanding triumphs achieved by radio astronomy of the solar system. Comprised of 10 chapters, this volume begins with an overview of the physical conditions in the upper layers of the Sun, the Moon, and the planets. This text then examines the three characteristics of radio emission, namely, the frequency spectrum, the polarization, and the angular spectrum. Other chapters consider the measurements of the i

  8. The Planets Approach to Migration Tools

    DEFF Research Database (Denmark)

    Zierau, Eld; van Wijk, Caroline

    2008-01-01

    This paper discusses the Planets approach to migration tool development. The approach consists of enhancing existing migration tools rather than developing tools from scratch. This pragmatic approach is based on the Planets view of the current situation for migration tools and two claims. The first...... claim is that the market will cover the required tools for commonly used formats. The second claim is that in the long term less tools will be required due to growing use of archiving standard formats. The Planets view on the current situation, the scope of tool development and the claims stated are...

  9. On the Formation of Rings around Giant Planets

    Science.gov (United States)

    Hyodo, Ryuki; Charnoz, Sebastien; Genda, Hidenori; Ohtsuki, Keiji

    2017-10-01

    The origin and age of the rings around giant planets are intensively debated. It has been proposed that Saturn's rings may form by tidal disruption of a Titan-sized primordial satellite that migrates inward due to the gas drag [1]. On the other hand, rings around giant planets may form by tidal disruption of a passing large Kuiper belt object during the late heavy bombardment [2].Recently, it is suggested that a proto-Rhea and a proto-Dione might have experienced a catastrophic collision (only 100 Myr ago) [3]. Following their arguments, we performed SPH simulations of impacts between such objects and found that the impact is indeed catastrophic [4]. Then, we investigated the long-term evolution of the debris by using N-body simulations and analytical arguments. We found that the debris quickly re-accrete into new generation of Rhea- or Dione-like satellite(s) as proposed by the previous work [3], but we didn't see any significant spreading of the debris to form Saturn's rings [4].In this work, we will discuss the current understanding of the origin of rings around giant planets by referring our recent papers [2,4].[1] Canup, R. 2010, Nature, 468, 943[2] Hyodo, R., Charnoz, S., Ohtsuki, K. & Genda, H. 2017, Icarus, 282, 195[3] Cuk, M., Dones, L., & Nesvorny, D. 2016, ApJ, 820, 97[4] Hyodo, R., & Charnoz, S. 2017, AJ, 154, 34

  10. High-reliability computing for the smarter planet

    Energy Technology Data Exchange (ETDEWEB)

    Quinn, Heather M [Los Alamos National Laboratory; Graham, Paul [Los Alamos National Laboratory; Manuzzato, Andrea [UNIV OF PADOVA; Dehon, Andre [UNIV OF PENN; Carter, Nicholas [INTEL CORPORATION

    2010-01-01

    The geometric rate of improvement of transistor size and integrated circuit performance, known as Moore's Law, has been an engine of growth for our economy, enabling new products and services, creating new value and wealth, increasing safety, and removing menial tasks from our daily lives. Affordable, highly integrated components have enabled both life-saving technologies and rich entertainment applications. Anti-lock brakes, insulin monitors, and GPS-enabled emergency response systems save lives. Cell phones, internet appliances, virtual worlds, realistic video games, and mp3 players enrich our lives and connect us together. Over the past 40 years of silicon scaling, the increasing capabilities of inexpensive computation have transformed our society through automation and ubiquitous communications. In this paper, we will present the concept of the smarter planet, how reliability failures affect current systems, and methods that can be used to increase the reliable adoption of new automation in the future. We will illustrate these issues using a number of different electronic devices in a couple of different scenarios. Recently IBM has been presenting the idea of a 'smarter planet.' In smarter planet documents, IBM discusses increased computer automation of roadways, banking, healthcare, and infrastructure, as automation could create more efficient systems. A necessary component of the smarter planet concept is to ensure that these new systems have very high reliability. Even extremely rare reliability problems can easily escalate to problematic scenarios when implemented at very large scales. For life-critical systems, such as automobiles, infrastructure, medical implantables, and avionic systems, unmitigated failures could be dangerous. As more automation moves into these types of critical systems, reliability failures will need to be managed. As computer automation continues to increase in our society, the need for greater radiation reliability is

  11. [Extrasolar terrestrial planets and possibility of extraterrestrial life].

    Science.gov (United States)

    Ida, Shigeru

    2003-12-01

    Recent development of research on extrasolar planets are reviewed. About 120 extrasolar Jupiter-mass planets have been discovered through the observation of Doppler shift in the light of their host stars that is caused by acceleration due to planet orbital motions. Although the extrasolar planets so far observed may be limited to gas giant planets and their orbits differ from those of giant planets in our Solar system (Jupiter and Saturn), the theoretically predicted probability of existence of extrasolar terrestrial planets that can have liquid water ocean on their surface is comparable to that of detectable gas giant planets. Based on the number of extrasolar gas giants detected so far, about 100 life-sustainable planets may exist within a range of 200 light years. Indirect observation of extrasolar terrestrial planets would be done with space telescopes within several years and direct one may be done within 20 years. The latter can detect biomarkers on these planets as well.

  12. Hydrodynamics of embedded planets' first atmospheres - III. The role of radiation transport for super-Earth planets

    Science.gov (United States)

    Cimerman, Nicolas P.; Kuiper, Rolf; Ormel, Chris W.

    2017-11-01

    The population of close-in super-Earths, with gas mass fractions of up to 10 per cent represents a challenge for planet formation theory: how did they avoid runaway gas accretion and collapsing to hot Jupiters despite their core masses being in the critical range of Mc ≃ 10 M⊕? Previous three-dimensional (3D) hydrodynamical simulations indicate that atmospheres of low-mass planets cannot be considered isolated from the protoplanetary disc, contrary to what is assumed in 1D-evolutionary calculations. This finding is referred to as the recycling hypothesis. In this paper, we investigate the recycling hypothesis for super-Earth planets, accounting for realistic 3D radiation hydrodynamics. Also, we conduct a direct comparison in terms of the evolution of the entropy between 1D and 3D geometries. We clearly see that 3D atmospheres maintain higher entropy: although gas in the atmosphere loses entropy through radiative cooling, the advection of high-entropy gas from the disc into the Bondi/Hill sphere slows down Kelvin-Helmholtz contraction, potentially arresting envelope growth at a sub-critical gas mass fraction. Recycling, therefore, operates vigorously, in line with results by previous studies. However, we also identify an `inner core' - in size ≈25 per cent of the Bondi radius - where streamlines are more circular and entropies are much lower than in the outer atmosphere. Future studies at higher resolutions are needed to assess whether this region can become hydrodynamically isolated on long time-scales.

  13. BINARY MINOR PLANETS V4.0

    Data.gov (United States)

    National Aeronautics and Space Administration — The data set lists orbital and physical properties for well-observed or suspected binary/multiple minor planets including the Pluto system, as inspired by Richardson...

  14. Planet Earth”is ours

    Science.gov (United States)

    Hartung, Jack

    Planet Earth” belongs to us. In this case, I'm not referring to the planet, earth, on which we live and which we consider our home in space. Instead, I'm saying that the upcoming television series, “Planet Earth,” belongs to us, the earth and space science community.Several years ago the AGU Council voted to provide $10,000 as “seed money” to initiate what was to become “Planet Earth.” To be sure, the series would not have happened without support from the Annenberg Foundation ($3,000,000) and the IBM Corporation ($1,000,000), but we were there, up front, where a little bit meant a lot.

  15. Symbiotic planet: a new look at evolution

    National Research Council Canada - National Science Library

    Margulis, Lynn

    1998-01-01

    ...." "In Symbiotic Planet, renowned scientist Lynn Margulis shows that symbiosis, which simply means members of different species living in physical contact with each other, is crucial to the origins...

  16. The origin of planets orbiting millisecond pulsars

    Science.gov (United States)

    Tavani, Marco; Brookshaw, Leigh

    1992-01-01

    A model for the formation of planets around millisecond pulsar which no longer have stellar companions is suggested. Detailed hydrodynamical models are presented which suggest that planet formation can occur either in a low-mass X-ray binary progenitor to a progenitor of a star-vaporizing millisecond pulsar when the neutron star is accreting material driven off its companion by X-ray irradiation or after a pulsar has formed and is vaporizing its companion. In both cases a circumbinary disk is created in which planets can form on a timescale of 10 exp 5 to 10 exp 6 yrs and the planets can survive a second phase in which the companion star moves toward the pulsar and is completely vaporized.

  17. Probing Extragalactic Planets Using Quasar Microlensing

    Science.gov (United States)

    Dai, Xinyu; Guerras, Eduardo

    2018-02-01

    Previously, planets have been detected only in the Milky Way galaxy. Here, we show that quasar microlensing provides a means to probe extragalactic planets in the lens galaxy, by studying the microlensing properties of emission close to the event horizon of the supermassive black hole of the background quasar, using the current generation telescopes. We show that a population of unbound planets between stars with masses ranging from Moon to Jupiter masses is needed to explain the frequent Fe Kα line energy shifts observed in the gravitationally lensed quasar RXJ 1131–1231 at a lens redshift of z = 0.295 or 3.8 billion lt-yr away. We constrain the planet mass-fraction to be larger than 0.0001 of the halo mass, which is equivalent to 2000 objects ranging from Moon to Jupiter mass per main-sequence star.

  18. BINARY MINOR PLANETS V6.0

    Data.gov (United States)

    National Aeronautics and Space Administration — The data set lists orbital and physical properties for well-observed or suspected binary/multiple minor planets including the Pluto system, as inspired by Richardson...

  19. BINARY MINOR PLANETS V5.0

    Data.gov (United States)

    National Aeronautics and Space Administration — The data set lists orbital and physical properties for well-observed or suspected binary/multiple minor planets including the Pluto system, as inspired by Richardson...

  20. BINARY MINOR PLANETS V1.0

    Data.gov (United States)

    National Aeronautics and Space Administration — We present a data table giving basic physical and orbital parameters for known binary minor planets in the Solar System (and Pluto/Charon) based on published...

  1. Thermal escape from extrasolar giant planets.

    Science.gov (United States)

    Koskinen, Tommi T; Lavvas, Panayotis; Harris, Matthew J; Yelle, Roger V

    2014-04-28

    The detection of hot atomic hydrogen and heavy atoms and ions at high altitudes around close-in extrasolar giant planets (EGPs) such as HD209458b implies that these planets have hot and rapidly escaping atmospheres that extend to several planetary radii. These characteristics, however, cannot be generalized to all close-in EGPs. The thermal escape mechanism and mass loss rate from EGPs depend on a complex interplay between photochemistry and radiative transfer driven by the stellar UV radiation. In this study, we explore how these processes change under different levels of irradiation on giant planets with different characteristics. We confirm that there are two distinct regimes of thermal escape from EGPs, and that the transition between these regimes is relatively sharp. Our results have implications for thermal mass loss rates from different EGPs that we discuss in the context of currently known planets and the detectability of their upper atmospheres.

  2. Characterizing Cool Giant Planets in Reflected Light

    Science.gov (United States)

    Marley, Mark

    2016-01-01

    While the James Webb Space Telescope will detect and characterize extrasolar planets by transit and direct imaging, a new generation of telescopes will be required to detect and characterize extrasolar planets by reflected light imaging. NASA's WFIRST space telescope, now in development, will image dozens of cool giant planets at optical wavelengths and will obtain spectra for several of the best and brightest targets. This mission will pave the way for the detection and characterization of terrestrial planets by the planned LUVOIR or HabEx space telescopes. In my presentation I will discuss the challenges that arise in the interpretation of direct imaging data and present the results of our group's effort to develop methods for maximizing the science yield from these planned missions.

  3. Astronomers find distant planet like Jupiter

    CERN Multimedia

    2003-01-01

    Astronomers searching for planetary systems like our solar system have found a planet similar to Jupiter orbiting a nearby star similar to our Sun, about 90 light-years from Earth, according to researchers (1/2 page).

  4. BINARY MINOR PLANETS V8.0

    Data.gov (United States)

    National Aeronautics and Space Administration — The data set lists orbital and physical properties for well-observed or suspected binary/multiple minor planets including the Pluto system, compiled from the...

  5. BINARY MINOR PLANETS V2.0

    Data.gov (United States)

    National Aeronautics and Space Administration — We present data tables giving basic orbital and physical parameters for well-observed or suspected binary/multiple minor planets and the Pluto system, based on a...

  6. BINARY MINOR PLANETS V9.0

    Data.gov (United States)

    National Aeronautics and Space Administration — The data set lists orbital and physical properties for well-observed or suspected binary/multiple minor planets including the Pluto system, compiled from the...

  7. BINARY MINOR PLANETS V3.0

    Data.gov (United States)

    National Aeronautics and Space Administration — We present data tables giving basic orbital and physical parameters for well-observed or suspected binary/multiple minor planets and the Pluto system, based on a...

  8. BINARY MINOR PLANETS V7.0

    Data.gov (United States)

    National Aeronautics and Space Administration — The data set lists orbital and physical properties for well-observed or suspected binary/multiple minor planets including the Pluto system, compiled from the...

  9. Thermal elastic deformations of the planet Mercury.

    Science.gov (United States)

    Liu, H.-S.

    1972-01-01

    The variation in solar heating due to the resonance rotation of Mercury produces periodic elastic deformations on the surface of the planet. The thermal stress and strain fields under Mercury's surface are calculated after certain simplifications. It is found that deformations penetrate to a greater depth than the variation of solar heating, and that the thermal strain on the surface of the planet pulsates with an amplitude of .004 and a period of 176 days.

  10. UNIVERSAL GRAVITATION AND MAGNETISM OF THE PLANETS

    Directory of Open Access Journals (Sweden)

    E.V. Savich

    2013-10-01

    Full Text Available The cores of the Solar System planets and the Sun are magnetized bodies, with the field of S-intensity, molten by the temperature of over million degrees. As similarly charged bodies, they interact with each other via repulsive forces that are considered, in the mechanism of gravitational attraction action, as resultant forces retaining the planets on the orbits at their inertial motion about the Sun.

  11. The SEEDs of Planet Formation: Indirect Signatures of Giant Planets in Transitional Disks

    Science.gov (United States)

    Grady, Carol; Currie, T.

    2012-01-01

    We live in a planetary system with 2 gas giant planets, and as a resu lt of RV, transit, microlensing, and transit timing studies have ide ntified hundreds of giant planet candidates in the past 15 years. Su ch studies have preferentially concentrated on older, low activity So lar analogs, and thus tell us little about .when, where, and how gian t planets form in their disks, or how frequently they form in disks associated with intermediate-mass stars.

  12. ECCENTRIC JUPITERS VIA DISK–PLANET INTERACTIONS

    Energy Technology Data Exchange (ETDEWEB)

    Duffell, Paul C.; Chiang, Eugene, E-mail: duffell@berkeley.edu, E-mail: echiang@astro.berkeley.edu [Department of Astronomy and Theoretical Astrophysics Center, University of California, Berkeley (United States)

    2015-10-20

    Numerical hydrodynamics calculations are performed to determine the conditions under which giant planet eccentricities can be excited by parent gas disks. Unlike in other studies, Jupiter-mass planets are found to have their eccentricities amplified—provided their orbits start off as eccentric. We disentangle the web of co-rotation, co-orbital, and external resonances to show that this finite-amplitude instability is consistent with that predicted analytically. Ellipticities can grow until they reach of order of the disk's aspect ratio, beyond which the external Lindblad resonances that excite eccentricity are weakened by the planet's increasingly supersonic epicyclic motion. Forcing the planet to still larger eccentricities causes catastrophic eccentricity damping as the planet collides into gap walls. For standard parameters, the range of eccentricities for instability is modest; the threshold eccentricity for growth (∼0.04) is not much smaller than the final eccentricity to which orbits grow (∼0.07). If this threshold eccentricity can be lowered (perhaps by non-barotropic effects), and if the eccentricity driving documented here survives in 3D, it may robustly explain the low-to-moderate eccentricities ≲0.1 exhibited by many giant planets (including Jupiter and Saturn), especially those without planetary or stellar companions.

  13. The HARPS-N Rocky Planet Search

    DEFF Research Database (Denmark)

    Motalebi, F.; Udry, S.; Gillon, M.

    2015-01-01

    We know now from radial velocity surveys and transit space missions that planets only a few times more massive than our Earth are frequent around solar-type stars. Fundamental questions about their formation history, physical properties, internal structure, and atmosphere composition are, however......, still to be solved. We present here the detection of a system of four low-mass planets around the bright (V = 5.5) and close-by (6.5 pc) star HD 219134. This is the first result of the Rocky Planet Search programme with HARPS-N on the Telescopio Nazionale Galileo in La Palma. The inner planet orbits...... the star in 3.0935 ± 0.0003 days, on a quasi-circular orbit with a semi-major axis of 0.0382 ± 0.0003 AU. Spitzer observations allowed us to detect the transit of the planet in front of the star making HD 219134 b the nearest known transiting planet to date. From the amplitude of the radial velocity...

  14. Survival of planets around shrinking stellar binaries.

    Science.gov (United States)

    Muñoz, Diego J; Lai, Dong

    2015-07-28

    The discovery of transiting circumbinary planets by the Kepler mission suggests that planets can form efficiently around binary stars. None of the stellar binaries currently known to host planets has a period shorter than 7 d, despite the large number of eclipsing binaries found in the Kepler target list with periods shorter than a few days. These compact binaries are believed to have evolved from wider orbits into their current configurations via the so-called Lidov-Kozai migration mechanism, in which gravitational perturbations from a distant tertiary companion induce large-amplitude eccentricity oscillations in the binary, followed by orbital decay and circularization due to tidal dissipation in the stars. Here we explore the orbital evolution of planets around binaries undergoing orbital decay by this mechanism. We show that planets may survive and become misaligned from their host binary, or may develop erratic behavior in eccentricity, resulting in their consumption by the stars or ejection from the system as the binary decays. Our results suggest that circumbinary planets around compact binaries could still exist, and we offer predictions as to what their orbital configurations should be like.

  15. Building Better Planet Populations for EXOSIMS

    Science.gov (United States)

    Garrett, Daniel; Savransky, Dmitry

    2018-01-01

    The Exoplanet Open-Source Imaging Mission Simulator (EXOSIMS) software package simulates ensembles of space-based direct imaging surveys to provide a variety of science and engineering yield distributions for proposed mission designs. These mission simulations rely heavily on assumed distributions of planetary population parameters including semi-major axis, planetary radius, eccentricity, albedo, and orbital orientation to provide heuristics for target selection and to simulate planetary systems for detection and characterization. The distributions are encoded in PlanetPopulation modules within EXOSIMS which are selected by the user in the input JSON script when a simulation is run. The earliest written PlanetPopulation modules available in EXOSIMS are based on planet population models where the planetary parameters are considered to be independent from one another. While independent parameters allow for quick computation of heuristics and sampling for simulated planetary systems, results from planet-finding surveys have shown that many parameters (e.g., semi-major axis/orbital period and planetary radius) are not independent. We present new PlanetPopulation modules for EXOSIMS which are built on models based on planet-finding survey results where semi-major axis and planetary radius are not independent and provide methods for sampling their joint distribution. These new modules enhance the ability of EXOSIMS to simulate realistic planetary systems and give more realistic science yield distributions.

  16. Protein production: planet, profit, plus people?

    Science.gov (United States)

    Aiking, Harry

    2014-07-01

    Food sustainability and food security are increasingly in the spotlight and increasingly intertwined. According to some projections we will need to nearly double food production in the next 4 decades. This article argues that protein production and consumption are pivotal to sustainability, because anthropogenic contributions to the nitrogen cycle are 100-200% compared with a contribution of 1-2% to the carbon cycle by mineral fuel combustion, with biodiversity as the main casualty. Because 1 kg animal protein requires ∼ 6 kg plant protein, its large-scale production by means of factory farming is a major driver of biodiversity loss, climate change, and freshwater depletion. Furthermore, intensive livestock production is associated with antibiotics resistance and increasing incidence of emerging diseases. Therefore, a "reversed" diet transition back to less animal protein could make a difference. Some European countries, such as the United Kingdom, Sweden, and The Netherlands, have published integrated policy reports addressing food security, sustainability, and health combined. The food industry is focusing on food safety and increasingly on sustainability. An important issue is consumer communication, because consumer "framing" is radically different from that of governmental and industrial policy makers. There is no "one size fits all." A huge range of differences exists between countries and between distinct groups of consumers within countries; getting consumers to change their diets in a more sustainable direction is likely to require much more than gentle nudging. National governments and the United Nations should assume their responsibilities and initiate a global strategy integrating sustainability, food security, nutrition, and equity. To date, the profit pillar of sustainability has taken precedence over planet and people. It is time to redress the balance. © 2014 American Society for Nutrition.

  17. Global models of planet formation and evolution

    Science.gov (United States)

    Mordasini, C.; Mollière, P.; Dittkrist, K.-M.; Jin, S.; Alibert, Y.

    2015-04-01

    Despite the strong increase in observational data on extrasolar planets, the processes that led to the formation of these planets are still not well understood. However, thanks to the high number of extrasolar planets that have been discovered, it is now possible to look at the planets as a population that puts statistical constraints on theoretical formation models. A method that uses these constraints is planetary population synthesis where synthetic planetary populations are generated and compared to the actual population. The key element of the population synthesis method is a global model of planet formation and evolution. These models directly predict observable planetary properties based on properties of the natal protoplanetary disc, linking two important classes of astrophysical objects. To do so, global models build on the simplified results of many specialized models that address one specific physical mechanism. We thoroughly review the physics of the sub-models included in global formation models. The sub-models can be classified as models describing the protoplanetary disc (of gas and solids), those that describe one (proto)planet (its solid core, gaseous envelope and atmosphere), and finally those that describe the interactions (orbital migration and N-body interaction). We compare the approaches taken in different global models, discuss the links between specialized and global models, and identify physical processes that require improved descriptions in future work. We then shortly address important results of planetary population synthesis like the planetary mass function or the mass-radius relationship. With these statistical results, the global effects of physical mechanisms occurring during planet formation and evolution become apparent, and specialized models describing them can be put to the observational test. Owing to their nature as meta models, global models depend on the results of specialized models, and therefore on the development of

  18. Spectro-Polarimetry of Self-Luminous Extrasolar Planets

    Indian Academy of Sciences (India)

    ... planets because their intrinsic temperature is extremely low but they are heated strongly by the impinging stellar radiation and hence radiation of such planets are the reflected star light that is governed by the stellar radiation, orbital distance and albedo of the planet. These planets cannot be resolved from the host stars.

  19. The mass of the Mars-sized exoplanet Kepler-138 b from transit timing.

    Science.gov (United States)

    Jontof-Hutter, Daniel; Rowe, Jason F; Lissauer, Jack J; Fabrycky, Daniel C; Ford, Eric B

    2015-06-18

    Extrasolar planets that pass in front of their host star (transit) cause a temporary decrease in the apparent brightness of the star, providing a direct measure of the planet's size and orbital period. In some systems with multiple transiting planets, the times of the transits are measurably affected by the gravitational interactions between neighbouring planets. In favourable cases, the departures from Keplerian orbits (that is, unaffected by gravitational effects) implied by the observed transit times permit the planetary masses to be measured, which is key to determining their bulk densities. Characterizing rocky planets is particularly difficult, because they are generally smaller and less massive than gaseous planets. Therefore, few exoplanets near the size of Earth have had their masses measured. Here we report the sizes and masses of three planets orbiting Kepler-138, a star much fainter and cooler than the Sun. We determine that the mass of the Mars-sized inner planet, Kepler-138 b, is 0.066(+0.059)(-0.037) Earth masses. Its density is 2.6(+2.4)(-1.5) grams per cubic centimetre. The middle and outer planets are both slightly larger than Earth. The middle planet's density (6.2(+5.8)(-3.4) grams per cubic centimetre) is similar to that of Earth, and the outer planet is less than half as dense at 2.1(+2.2)(-1.2) grams per cubic centimetre, implying that it contains a greater portion of low-density components such as water and hydrogen.

  20. TERRESTRIAL PLANET FORMATION DURING THE MIGRATION AND RESONANCE CROSSINGS OF THE GIANT PLANETS

    Energy Technology Data Exchange (ETDEWEB)

    Lykawka, Patryk Sofia [Astronomy Group, Faculty of Social and Natural Sciences, Kinki University, Shinkamikosaka 228-3, Higashiosaka-shi, Osaka 577-0813 (Japan); Ito, Takashi, E-mail: patryksan@gmail.com [National Astronomical Observatory of Japan, Osawa 2-21-1, Mitaka, Tokyo 181-8588 (Japan)

    2013-08-10

    The newly formed giant planets may have migrated and crossed a number of mutual mean motion resonances (MMRs) when smaller objects (embryos) were accreting to form the terrestrial planets in the planetesimal disk. We investigated the effects of the planetesimal-driven migration of Jupiter and Saturn, and the influence of their mutual 1:2 MMR crossing on terrestrial planet formation for the first time, by performing N-body simulations. These simulations considered distinct timescales of MMR crossing and planet migration. In total, 68 high-resolution simulation runs using 2000 disk planetesimals were performed, which was a significant improvement on previously published results. Even when the effects of the 1:2 MMR crossing and planet migration were included in the system, Venus and Earth analogs (considering both orbits and masses) successfully formed in several runs. In addition, we found that the orbits of planetesimals beyond a {approx} 1.5-2 AU were dynamically depleted by the strengthened sweeping secular resonances associated with Jupiter's and Saturn's more eccentric orbits (relative to the present day) during planet migration. However, this depletion did not prevent the formation of massive Mars analogs (planets with more than 1.5 times Mars's mass). Although late MMR crossings (at t > 30 Myr) could remove such planets, Mars-like small mass planets survived on overly excited orbits (high e and/or i), or were completely lost in these systems. We conclude that the orbital migration and crossing of the mutual 1:2 MMR of Jupiter and Saturn are unlikely to provide suitable orbital conditions for the formation of solar system terrestrial planets. This suggests that to explain Mars's small mass and the absence of other planets between Mars and Jupiter, the outer asteroid belt must have suffered a severe depletion due to interactions with Jupiter/Saturn, or by an alternative mechanism (e.g., rogue super-Earths)

  1. The effect of lunarlike satellites on the orbital infrared light curves of Earth-analog planets.

    Science.gov (United States)

    Moskovitz, Nicholas A; Gaidos, Eric; Williams, Darren M

    2009-04-01

    We have investigated the influence of lunarlike satellites on the infrared orbital light curves of Earth-analog extrasolar planets. Such light curves will be obtained by NASA's Terrestrial Planet Finder (TPF) and ESA's Darwin missions as a consequence of repeat observations to confirm the companion status of a putative planet and determine its orbit. We used an energy balance model to calculate disk-averaged infrared (bolometric) fluxes from planet-satellite systems over a full orbital period (one year). The satellites are assumed to lack an atmosphere, have a low thermal inertia like that of the Moon, and span a range of plausible radii. The planets are assumed to have thermal and orbital properties that mimic those of Earth, while their obliquities and orbital longitudes of inferior conjunction remain free parameters. Even if the gross thermal properties of the planet can be independently constrained (e.g., via spectroscopy or visible-wavelength detection of specular glint from a surface ocean), only the largest (approximately Mars-sized) lunarlike satellites can be detected by light curve data from a TPF-like instrument (i.e., one that achieves a photometric signal-to-noise ratio of 10 to 20 at infrared wavelengths). Nondetection of a lunarlike satellite can obfuscate the interpretation of a given system's infrared light curve so that it may resemble a single planet with high obliquity, different orbital longitude of vernal equinox relative to inferior conjunction, and in some cases drastically different thermal characteristics. If the thermal properties of the planet are not independently established, then the presence of a lunarlike satellite cannot be inferred from infrared data, which would thus demonstrate that photometric light curves alone can only be used for preliminary study, and the addition of spectroscopic data will be necessary.

  2. A giant planet around HD95086 ?

    Science.gov (United States)

    Rameau, Julien; Chauvin, Gaël; Lagrange, Anne-Marie; Meshkat, Tiffany; Boccaletti, Anthony; Quanz, Sascha P.; Bonnefoy, Mickaël; Bailey, Vanessa; Kenworthy, Matthew; Currie, Thayne; Girard, Julien H.; Delorme, Philippe; Desidera, Silvano; Dumas, Christophe; Mordasini, Christoph; Klahr, Hubert; Bonavita, Mariangela

    2013-07-01

    Understanding planetary systems formation and evolution has become one of the challenges in as- tronomy, since the discovery of the first exoplanet around the solar-type star 51 Peg in the 90's. While more than 800 planets (mostly giants) closer than a few AU have been identified with radial velocity and transit techniques, very few have been imaged and definitely confirmed around stars, at separations below a hundred of astronomical units. Direct imaging detection of exoplanet is indeed a major frontier in planetary astrophysics. It surveys a region of semi-major axes (> 5 AU) that is almost inaccessible to other methods. Moreover, the planets imaged so far orbit young stars; indeed the young planets are still hot and the planet-star contrasts are compatible with the detection limits currently achievable, in contrast with similar planets in older systems. Noticeably, the stars are of early-types, and surrounded by debris disks, i.e. disks populated at least by small grains with lifetimes so short that they must be permanently produced, probably by destruction (evaporation, collisions) of larger solid bodies. Consequently, every single discovery has a tremendous impact on the understanding of the formation, the dynamical evolution, and the physics of giant planets. In this context, I will present our recent discovery of one faint companion to a nearby, dusty, and young A-type star (at 56 AU projected separation). Background contaminants are rejected with high confidence level based on both astrometry and photometry with three dataset at more than a year-time-laps and two different wavelength regimes. From the system age (10 to 17 Myr) and from model-dependent luminosity estimates, we derive mass of 4 to 5 Jupiter mass. This planet is therefore the one with the lowest mass ever imaged around a star. Given its orbital and physical properties, I will discuss the implication on its atmosphere with respect to other imaged companions but also on its formation.

  3. FUNDAMENTAL PROPERTIES OF KEPLER PLANET-CANDIDATE HOST STARS USING ASTEROSEISMOLOGY

    Energy Technology Data Exchange (ETDEWEB)

    Huber, Daniel; Lissauer, Jack J.; Rowe, Jason F. [NASA Ames Research Center, Moffett Field, CA 94035 (United States); Chaplin, William J. [School of Physics and Astronomy, University of Birmingham, Birmingham B15 2TT (United Kingdom); Christensen-Dalsgaard, Jorgen; Kjeldsen, Hans; Handberg, Rasmus; Karoff, Christoffer; Lund, Mikkel N.; Lundkvist, Mia [Stellar Astrophysics Centre, Department of Physics and Astronomy, Aarhus University, Ny Munkegade 120, DK-8000 Aarhus C (Denmark); Gilliland, Ronald L. [Center for Exoplanets and Habitable Worlds, The Pennsylvania State University, 525 Davey Lab, University Park, PA 16802 (United States); Buchhave, Lars A. [Niels Bohr Institute, University of Copenhagen, DK-2100 Copenhagen (Denmark); Fischer, Debra A.; Basu, Sarbani [Department of Astronomy, Yale University, New Haven, CT 06511 (United States); Sanchis-Ojeda, Roberto [Department of Physics, Massachusetts Institute of Technology, 77 Massachusetts Ave., Cambridge, MA 02139 (United States); Hekker, Saskia [Astronomical Institute ' ' Anton Pannekoek' ' , University of Amsterdam, Science Park 904, 1098 XH Amsterdam (Netherlands); Howard, Andrew W. [Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI 96822 (United States); Isaacson, Howard; Marcy, Geoffrey W. [Department of Astronomy, University of California, Berkeley, CA 94720 (United States); Latham, David W., E-mail: daniel.huber@nasa.gov [Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138 (United States); and others

    2013-04-20

    We have used asteroseismology to determine fundamental properties for 66 Kepler planet-candidate host stars, with typical uncertainties of 3% and 7% in radius and mass, respectively. The results include new asteroseismic solutions for four host stars with confirmed planets (Kepler-4, Kepler-14, Kepler-23 and Kepler-25) and increase the total number of Kepler host stars with asteroseismic solutions to 77. A comparison with stellar properties in the planet-candidate catalog by Batalha et al. shows that radii for subgiants and giants obtained from spectroscopic follow-up are systematically too low by up to a factor of 1.5, while the properties for unevolved stars are in good agreement. We furthermore apply asteroseismology to confirm that a large majority of cool main-sequence hosts are indeed dwarfs and not misclassified giants. Using the revised stellar properties, we recalculate the radii for 107 planet candidates in our sample, and comment on candidates for which the radii change from a previously giant-planet/brown-dwarf/stellar regime to a sub-Jupiter size or vice versa. A comparison of stellar densities from asteroseismology with densities derived from transit models in Batalha et al. assuming circular orbits shows significant disagreement for more than half of the sample due to systematics in the modeled impact parameters or due to planet candidates that may be in eccentric orbits. Finally, we investigate tentative correlations between host-star masses and planet-candidate radii, orbital periods, and multiplicity, but caution that these results may be influenced by the small sample size and detection biases.

  4. Value of Hipparcos Catalogue shown by planet assessments

    Science.gov (United States)

    1996-08-01

    , or deuterium. Even the "worst-case" mass quoted here for the companion of 47 Ursae Majoris, 22 Jupiter masses, is only a maximum, not a measurement. So the companion is almost certainly a true planet with less than 17 times the mass of Jupiter. For the star 70 Virginis, the distance newly established by Hipparcos is 59 light-years. Even on the least favourable assumptions about its orbit, the companion cannot have more than 65 Jupiter masses. It could be brown dwarf rather than a planet, but not a true star. Much more ambiguous is the result for 51 Pegasi. Its distance is 50 light-years and theoretically the companion could have more than 500 Jupiter masses, or half the mass of the Sun. This is a peculiar case anyway, because the companion is very close to 51 Pegasi. Small planets of the size of the Earth might be more promising as abodes of life than the large planets detectable by present astronomical methods. Space scientists are now reviewing methods of detecting the presence of life on alien planets by detecting the infrared signature of ozone in a planet's atmosphere. Ozone is a by-product of oxygen gas, which in turn is supposed to be generated only by life similar to that on the Earth. Meanwhile the detection of planets of whatever size is a tour de force for astronomers, and by analogy with the Solar System one may suppose that large planets are often likely to be accompanied by smaller ones. "Hipparcos was not conceived to look for planets," comments Michael Perryman, ESA's project scientist for Hipparcos, "and this example of assistance to our fellow-astronomers involves a very small sample of our measurements. But it is a timely result when we are considering planet-hunting missions for the 21st Century. The possibilities include a super-Hipparcos that could detect directly the wobbles in nearby stars due to the presence of planets." Hipparcos Catalogue ready for use The result from Hipparcos on alien planets coincides with the completion of the Hipparcos

  5. Mapping the Region in the Nearest Star System to Search for Habitable Planets

    Science.gov (United States)

    Lissauer, Jack J.; Quarles, B.

    2015-01-01

    Circumstellar planets within the alpha Centauri AB star system have been suggested through formation models and recent observations, and ACESat (Belikov et al. AAS Meeting #225, #311.01, 2015) is a proposed space mission designed to directly image Earth-sized planets in the habitable zones of both of these stars. The alpha Centauri system is billions of years old, so planets are only expected to be found in regions where their orbits are long-lived. We evaluate the extent of the regions within the alpha Centauri AB star system where small planets are able to orbit for billion-year timescales and we map the positions in the sky plane where planets on stable orbits about either stellar component may appear. We confirm the qualitative results of Wiegert & Holman (Astron. J. 113, 1445, 1997) regarding the approximate size of the regions of stable orbits, which are larger for retrograde orbits relative to the binary than for prograde orbits. Additionally, we find that mean motion resonances with the binary orbit leave an imprint on the limits of orbital stability, and the effects of the Lidov-Kozai mechanism are also readily apparent. Overall, orbits in the habitable zones near the plane of the binary are stable, whereas high-inclination orbits are short-lived.

  6. PLANET TOPERS: Planets, Tracing the Transfer, Origin, Preservation, and Evolution of their ReservoirS.

    Science.gov (United States)

    Dehant, V; Asael, D; Baland, R M; Baludikay, B K; Beghin, J; Belza, J; Beuthe, M; Breuer, D; Chernonozhkin, S; Claeys, Ph; Cornet, Y; Cornet, L; Coyette, A; Debaille, V; Delvigne, C; Deproost, M H; De WInter, N; Duchemin, C; El Atrassi, F; François, C; De Keyser, J; Gillmann, C; Gloesener, E; Goderis, S; Hidaka, Y; Höning, D; Huber, M; Hublet, G; Javaux, E J; Karatekin, Ö; Kodolanyi, J; Revilla, L Lobo; Maes, L; Maggiolo, R; Mattielli, N; Maurice, M; McKibbin, S; Morschhauser, A; Neumann, W; Noack, L; Pham, L B S; Pittarello, L; Plesa, A C; Rivoldini, A; Robert, S; Rosenblatt, P; Spohn, T; Storme, J -Y; Tosi, N; Trinh, A; Valdes, M; Vandaele, A C; Vanhaecke, F; Van Hoolst, T; Van Roosbroek, N; Wilquet, V; Yseboodt, M

    2016-11-01

    The Interuniversity Attraction Pole (IAP) 'PLANET TOPERS' (Planets: Tracing the Transfer, Origin, Preservation, and Evolution of their Reservoirs) addresses the fundamental understanding of the thermal and compositional evolution of the different reservoirs of planetary bodies (core, mantle, crust, atmosphere, hydrosphere, cryosphere, and space) considering interactions and feedback mechanisms. Here we present the first results after 2 years of project work.

  7. The Gemini Planet Imager Exoplanet Survey

    Science.gov (United States)

    Macintosh, Bruce

    The Gemini Planet Imager (GPI) is a next-generation coronagraph constructed for the Gemini Observatory. GPI will see first light this fall. It will be the most advanced planet-imaging system in operation - an order of magnitude more sensitive than any current instrument, capable of detecting and spectroscopically characterizing young Jovian planets 107 times fainter than their parent star at separations of 0.2 arcseconds. GPI was built from the beginning as a facility-class survey instrument, and the observatory will employ it that way. Our team has been selected by Gemini Observatory to carry out an 890-hour program - the GPI Exoplanet Survey (GPIES) campaign from 2014-2017. We will observe 600 stars spanning spectral types A-M. We will use published young association catalogs and a proprietary list in preparation that adds several hundred new young (adolescent (view of the nature of wide-orbit planetary companions, informing our knowledge of solar system formation to guide future NASA planet hunting missions, while simultaneously offering a real- world program using the techniques - from integral field spectroscopy to advanced coronagraphy - that will someday be used to directly image Earthlike planets from space.

  8. Search for extra-solar planets

    Science.gov (United States)

    Skuljan, J.

    2003-10-01

    A number of different observational techniques are used today for the detection of planets beyond our solar system. Most of them are indirect methods, based on dynamical or photometric effects induced by the planet and measured on the parent star. The most successful technique so far has been the Doppler (radial-velocity) method, based on precise measurements of small variations in the radial velocity of the parent star. About one hundred extra-solar planets have been discovered by this technique. Other methods are based on astrometric measurements, direct imaging, photometry, interferometry and gravitational microlensing. Some of these techniques are already able to produce positive results, but many of them are future projects needing more advanced instrumentation. In this paper the most important techniques for extra-solar planet detection will be reviewed and their results summarized. In the second part, two different projects carried out at Mt John University Observatory, Lake Tekapo, New Zealand will be presented, both involved in planet hunting. One is the HERCULES radial-velocity programme and the other is the MOA microlensing project.

  9. GEMINI PLANET IMAGER SPECTROSCOPY OF THE HR 8799 PLANETS c AND d

    Energy Technology Data Exchange (ETDEWEB)

    Ingraham, Patrick; Macintosh, Bruce [Kavli Institute for Particle Astrophysics and Cosmology, Stanford University, Stanford, CA 94305 (United States); Marley, Mark S. [NASA Ames Research Center, Moffett Field, CA 94035 (United States); Saumon, Didier [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Marois, Christian; Dunn, Jennifer; Erikson, Darren [NRC Herzberg Astronomy and Astrophysics, 5071 West Saanich Road, Victoria, BC V9E 2E7 (Canada); Barman, Travis [Lunar and Planetary Laboratory, University of Arizona, Tucson, Arizona 85721-0092 (United States); Bauman, Brian [Lawrence Livermore National Lab, 7000 East Avenue, Livermore, CA 94551 (United States); Burrows, Adam [Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544 (United States); Chilcote, Jeffrey K.; Fitzgerald, Michael P. [Department of Physics and Astronomy, UCLA, Los Angeles, CA 90095 (United States); De Rosa, Robert J. [School of Earth and Space Exploration, Arizona State University, PO Box 871404, Tempe, AZ 85287 (United States); Dillon, Daren; Gavel, Donald [Department of Astronomy, UC Santa Cruz, 1156 High Street, Santa Cruz, CA 95064 (United States); Doyon, René [Department de Physique, Université de Montréal, Montréal QC H3C 3J7 (Canada); Goodsell, Stephen J.; Hartung, Markus; Hibon, Pascale [Gemini Observatory, Casilla 603, La Serena (Chile); Graham, James R. [Department of Astronomy, UC Berkeley, Berkeley CA, 94720 (United States); and others

    2014-10-10

    During the first-light run of the Gemini Planet Imager we obtained K-band spectra of exoplanets HR 8799 c and d. Analysis of the spectra indicates that planet d may be warmer than planet c. Comparisons to recent patchy cloud models and previously obtained observations over multiple wavelengths confirm that thick clouds combined with horizontal variation in the cloud cover generally reproduce the planets' spectral energy distributions. When combined with the 3 to 4 μm photometric data points, the observations provide strong constraints on the atmospheric methane content for both planets. The data also provide further evidence that future modeling efforts must include cloud opacity, possibly including cloud holes, disequilibrium chemistry, and super-solar metallicity.

  10. Dynamics of the Outer Planets

    Science.gov (United States)

    1992-01-01

    vorticty consrvatio directly from the shallow water equations: dv .+ fk x v=-gVh. and sad da•+hV~v=O where h := h, - h, is the layer thidmess, h. is the...Jovian vortices, su(ch as the Great Red Spot ( GIRS ) of Jupiter and White Ovals. In particular we argue that the GIRS shows both finite L,. effects. On...located just south of the flow’s stagnation point. The southern part of the GIRS has grown ill size until it lies in a. region of large prograde shear

  11. The origin of high eccentricity planets: The dispersed planet formation regime for weakly magnetized disks

    Directory of Open Access Journals (Sweden)

    Yusuke Imaeda

    2017-03-01

    Full Text Available In the tandem planet formation regime, planets form at two distinct sites where solid particles are densely accumulated due to the on/off state of the magnetorotational instability (MRI. We found that tandem planet formation can reproduce the solid component distribution of the Solar System and tends to produce a smaller number of large planets through continuous pebble flow into the planet formation sites. In the present paper, we investigate the dependence of tandem planet formation on the vertical magnetic field of the protoplanetary disk. We calculated two cases of Bz=3.4×10−3 G and Bz=3.4×10−5 G at 100 AU as well as the canonical case of Bz=3.4×10−4 G. We found that tandem planet formation holds up well in the case of the strong magnetic field (Bz=3.4×10−3 G. On the other hand, in the case of a weak magnetic field (Bz=3.4×10−5 G at 100 AU, a new regime of planetary growth is realized: the planets grow independently at different places in the dispersed area of the MRI-suppressed region of r=8−30 AU at a lower accretion rate of M˙<10−7.4 M⊙yr−1. We call this the “dispersed planet formation” regime. This may lead to a system with a larger number of smaller planets that gain high eccentricity through mutual collisions.

  12. Venus Express en route to probe the planet's hidden mysteries

    Science.gov (United States)

    2005-11-01

    reduced to once daily. If needed, trajectory correction manoeuvres can go ahead at the half-way stage in January. When making its closest approach, Venus Express will face far tougher conditions than those encountered by Mars Express on nearing the Red Planet. For while Venus's size is indeed similar to that of the Earth, its mass is 7.6 times that of Mars, with gravitational attraction to match. To resist this greater gravitational pull, the spacecraft will have to ignite its main engine for 53 minutes in order to achieve 1.3 km/second deceleration and place itself into a highly elliptical orbit around the planet. Most of its 570 kg of propellant will be used for this manoeuvre. A second engine firing will be necessary in order to reach final operational orbit: a polar elliptical orbit with 12-hour crossings. This will enable the probe to make approaches to within 250 km of the planet's surface and withdraw to distances of up to 66 000 km, so as to carry out close-up observations and also get an overall perspective. Exploring other planets to better understand planet Earth "The launch of Venus Express is a further illustration of Europe's determination to study the various bodies in our solar system", stressed Professor David Southwood, the Director of ESA's science programmes. "We started in 2003 with the launch of Mars Express to the Red Planet and Smart-1 to the Moon and both these missions have amply exceeded our expectations. Venus Express marks a further step forward, with a view to eventually rounding off our initial overview of our immediate planetary neighbours with the BepiColombo mission to Mercury to be launched in 2013." "With Venus Express, we fully intend to demonstrate yet again that studying the planets is of vital importance for life here on Earth", said Jean Jacques Dordain, ESA Director General. "To understand climate change on Earth and all the contributing factors, we cannot make do with solely observing our own planet. We need to decipher the

  13. Planetesimals early differentiation and consequences for planets

    CERN Document Server

    Weiss, Benjamin P

    2017-01-01

    Processes governing the evolution of planetesimals are critical to understanding how rocky planets are formed, how water is delivered to them, the origin of planetary atmospheres, how cores and magnetic dynamos develop, and ultimately, which planets have the potential to be habitable. Theoretical advances and new data from asteroid and meteorite observations, coupled with spacecraft missions such as Rosetta and Dawn, have led to major advances in this field over the last decade. This transdisciplinary volume presents an authoritative overview of the latest in our understanding of the processes of planet formation. Combining meteorite, asteroid and icy body observations with theory and modelling of accretion and orbital dynamics, this text also provides insights into the exoplanetary system and the search for habitable worlds. This is an essential reference for those interested in planetary formation, solar system dynamics, exoplanets and planetary habitability.

  14. Eating a planet and spinning up

    Science.gov (United States)

    Qureshi, Ahmed; Naoz, Smadar; Shkolnik, Evgenya L.

    2018-01-01

    One of the predictions of high eccentricity planetary migration is that many planets will end up plunging into their host stars. We investigate the consequence of planetary mergers on their stellar hosts’ spin-period. Energy and angular momentum conservation yield that a planet consumption by a star will spin-up of the star. We find that our calculations align with the observed bifurcation in the stellar spin-period in young clusters. After a Sun-like star has eaten a planet, it will then, spin down due to magnetic braking, consistent with the observed lack of fast rotators in old clusters. The agreement between the calculations presented here and the observed spin-period of stars in young clusters provides circumstantial evidence that planetary accretion onto their host stars is a generic feature in planetary-system evolution.

  15. Dark matter and the habitability of planets

    Energy Technology Data Exchange (ETDEWEB)

    Hooper, Dan; Steffen, Jason H., E-mail: dhooper@fnal.gov, E-mail: jsteffen@fnal.gov [Center for Particle Astrophysics, Fermi National Accelerator Laboratory, Batavia, IL 60510 (United States)

    2012-07-01

    In many models, dark matter particles can elastically scatter with nuclei in planets, causing those particles to become gravitationally bound. While the energy expected to be released through the subsequent annihilations of dark matter particles in the interior of the Earth is negligibly small (a few megawatts in the most optimistic models), larger planets that reside in regions with higher densities of slow moving dark matter could plausibly capture and annihilate dark matter at a rate high enough to maintain liquid water on their surfaces, even in the absence of additional energy from starlight or other sources. On these rare planets, it may be dark matter rather than light from a host star that makes it possible for life to emerge, evolve, and survive.

  16. Planck intermediate results - LII. Planet flux densities

    DEFF Research Database (Denmark)

    Akrami, Y.; Ashdown, M.; Aumont, J.

    2017-01-01

    Measurements of flux density are described for five planets, Mars, Jupiter, Saturn, Uranus, and Neptune, across the six Planck High Frequency Instrument frequency bands (100–857 GHz) and these are then compared with models and existing data. In our analysis, we have also included estimates...... of the brightness of Jupiter and Saturn at the three frequencies of the Planck Low Frequency Instrument (30, 44, and 70 GHz). The results provide constraints on the intrinsic brightness and the brightness time-variability of these planets. The majority of the planet flux density estimates are limited by systematic...... errors, but still yield better than 1% measurements in many cases. Applying data from Planck HFI, the Wilkinson Microwave Anisotropy Probe (WMAP), and the Atacama Cosmology Telescope (ACT) to a model that incorporates contributions from Saturn’s rings to the planet’s total flux density suggests a best...

  17. Spectroscopic follow up of Kepler planet candidates

    DEFF Research Database (Denmark)

    Latham..[], D. W.; Cochran, W. D.; Marcy, G.W.

    2010-01-01

    Spectroscopic follow-up observations play a crucial role in the confirmation and characterization of transiting planet candidates identified by Kepler. The most challenging part of this work is the determination of radial velocities with a precision approaching 1 m/s in order to derive masses from...... spectroscopic orbits. The most precious resource for this work is HIRES on Keck I, to be joined by HARPS-North on the William Herschel Telescope when that new spectrometer comes on line in two years. Because a large fraction of the planet candidates are in fact stellar systems involving eclipsing stars...... and not planets, our strategy is to start with reconnaissance spectroscopy using smaller telescopes, to sort out and reject as many of the false positives as possible before going to Keck. During the first Kepler observing season in 2009, more than 100 nights of telescope time were allocated for this work, using...

  18. International Conference and Advanced School Planet Earth

    CERN Document Server

    Jeltsch, Rolf; Pinto, Alberto; Viana, Marcelo

    2015-01-01

    The focus of this volume is research carried out as part of the program Mathematics of Planet Earth, which provides a platform to showcase the essential role of mathematics in addressing planetary problems and creating a context for mathematicians and applied scientists to foster mathematical and interdisciplinary developments that will be necessary to tackle a myriad of issues and meet future global challenges. Earth is a planet with dynamic processes in its mantle, oceans and atmosphere creating climate, causing natural disasters, and influencing fundamental aspects of life and life-supporting systems. In addition to these natural processes, human activity has increased to the point where it influences the global climate, impacts the ability of the planet to feed itself and threatens the stability of these systems. Issues such as climate change, sustainability, man-made disasters, control of diseases and epidemics, management of resources, risk analysis, and global integration have come to the fore. Written...

  19. Neutron star planets: Atmospheric processes and irradiation

    Science.gov (United States)

    Patruno, A.; Kama, M.

    2017-12-01

    Of the roughly 3000 neutron stars known, only a handful have sub-stellar companions. The most famous of these are the low-mass planets around the millisecond pulsar B1257+12. New evidence indicates that observational biases could still hide a wide variety of planetary systems around most neutron stars. We consider the environment and physical processes relevant to neutron star planets, in particular the effect of X-ray irradiation and the relativistic pulsar wind on the planetary atmosphere. We discuss the survival time of planet atmospheres and the planetary surface conditions around different classes of neutron stars, and define a neutron star habitable zone based on the presence of liquid water and retention of an atmosphere. Depending on as-yet poorly constrained aspects of the pulsar wind, both Super-Earths around B1257+12 could lie within its habitable zone.

  20. Why 400 Years to Discover Countless Planets?

    Science.gov (United States)

    Carr, Paul H.

    2011-04-01

    In 1584, Dominican monk Giordano Bruno envisioned the stars as "countless suns with countless earths, all rotating around their suns." Searching for intellectual freedom, he fled his native Italy to Protestant Switzerland and Germany, but in 1600 the Roman Inquisition condemned him for heresy. He was burned at the stake. Fast-forwarding to 1995, the Swiss astronomers Michel Mayor and Didier Queloz announced the discovery of a planet orbiting a star similar to our sun (51 Pegasi). In 2010, 500 planets had been found orbiting 421 stars. On Feb 2, 2011, NASA announced 1200 planet candidates. It took 400 years for telescope technology to advance and for Copernicus, Galileo, Newton, Bradley, and Foucault to make major contributions, culminating in today's astrophysics with digital imaging and processing. Contrasting with Bruno, in 2010 Dominican Francisco Ayala, who had been president of the Sigma Xi and AAAS, won the 1.6M Templeton Prize for affirming life's spiritual dimension.

  1. A Maximum Radius for Habitable Planets.

    Science.gov (United States)

    Alibert, Yann

    2015-09-01

    We compute the maximum radius a planet can have in order to fulfill two constraints that are likely necessary conditions for habitability: 1- surface temperature and pressure compatible with the existence of liquid water, and 2- no ice layer at the bottom of a putative global ocean, that would prevent the operation of the geologic carbon cycle to operate. We demonstrate that, above a given radius, these two constraints cannot be met: in the Super-Earth mass range (1-12 Mearth), the overall maximum that a planet can have varies between 1.8 and 2.3 Rearth. This radius is reduced when considering planets with higher Fe/Si ratios, and taking into account irradiation effects on the structure of the gas envelope.

  2. The formation of planets by disc fragmentation

    Directory of Open Access Journals (Sweden)

    Stamatellos Dimitris

    2013-04-01

    Full Text Available I discuss the role that disc fragmentation plays in the formation of gas giant and terrestrial planets, and how this relates to the formation of brown dwarfs and low-mass stars, and ultimately to the process of star formation. Protostellar discs may fragment, if they are massive enough and can cool fast enough, but most of the objects that form by fragmentation are brown dwarfs. It may be possible that planets also form, if the mass growth of a proto-fragment is stopped (e.g. if this fragment is ejected from the disc, or suppressed and even reversed (e.g by tidal stripping. I will discuss if it is possible to distinguish whether a planet has formed by disc fragmentation or core accretion, and mention of a few examples of observed exoplanets that are suggestive of formation by disc fragmentation.

  3. Stochasticity and predictability in terrestrial planet formation

    Science.gov (United States)

    Hoffmann, Volker; Grimm, Simon L.; Moore, Ben; Stadel, Joachim

    2017-02-01

    Terrestrial planets are thought to be the result of a vast number of gravitational interactions and collisions between smaller bodies. We use numerical simulations to show that practically identical initial conditions result in a wide array of final planetary configurations. This is a result of the chaotic evolution of trajectories which are highly sensitive to minuscule displacements. We determine that differences between systems evolved from virtually identical initial conditions can be larger than the differences between systems evolved from very different initial conditions. This implies that individual simulations lack predictive power. For example, there is not a reproducible mapping between the initial and final surface density profiles. However, some key global properties can still be extracted if the statistical spread across many simulations is considered. Based on these spreads, we explore the collisional growth and orbital properties of terrestrial planets, which assemble from different initial conditions (we vary the initial planetesimal distribution, planetesimal masses, and giant planet orbits.). Confirming past work, we find that the resulting planetary systems are sculpted by sweeping secular resonances. Configurations with giant planets on eccentric orbits produce fewer and more massive terrestrial planets on tighter orbits than those with giants on circular orbits. This is further enhanced if the initial mass distribution is biased to the inner regions. In all cases, the outer edge of the system is set by the final location of the ν6 resonance and we find that the mass distribution peaks at the ν5 resonance. Using existing observations, we find that extrasolar systems follow similar trends. Although differences between our numerical modelling and exoplanetary systems remain, we suggest that CoRoT-7, HD 20003 and HD 20781 may host undetected giant planets.

  4. Planet Earth week featured at Fall Meeting

    Science.gov (United States)

    The Fall Meeting has been dubbed “Planet Earth Week,” in part to salute the upcoming 7-week PBS television series and university course that will be previewed at the meeting. At least four of the seven 1-hour segments of “Planet Earth” will be shown daily at the the Fall Meeting. AGU provided some of the seed money for the new series, which will have its television premiere on Wednesday, January 22, 1986, on PBS at 9 P.M. EST.

  5. The Magnetic Field of Planet Earth

    DEFF Research Database (Denmark)

    Hulot, G.; Finlay, Chris; Constable, C. G.

    2010-01-01

    The magnetic field of the Earth is by far the best documented magnetic field of all known planets. Considerable progress has been made in our understanding of its characteristics and properties, thanks to the convergence of many different approaches and to the remarkable fact that surface rocks...... yr) to the longest (virtually the age of the Earth) time scales are finally reviewed, underlining the respective roles of the magnetohydodynamics at work in the core, and of the slow dynamic evolution of the planet as a whole....

  6. Guide to the universe inner planets

    CERN Document Server

    Grier, Jennifer

    2009-01-01

    This volume in the Greenwood Guides to the Universe series covers the inner planets-Mercury, Venus, Earth, and Mars. Thematic chapters discuss all of the many areas of astronomical research surrounding each subject, providing readers with the most up-to-date understanding of current knowledge and the ways in which it has been obtained. Like all of the books in this series, Inner Planets is scientifically sound, but written with the student in mind. It is an excellent first step for researching the exciting scientific discoveries of the Earth and its closest neighbors.

  7. Selection effects in Doppler velocity planet searches

    Science.gov (United States)

    O'Toole, Simon; Tinney, Chris; Jones, Hugh

    2008-05-01

    The majority of extra-solar planets have been discovered by measuring the Doppler velocities of the host star. Like all exoplanet detection methods, the Doppler method is rife with observational biases. Before any robust comparison of mass, orbital period and eccentricity distributions can be made with theory, a detailed understanding of these selection effects is required, something which up to now is lacking. We present here a progress report on our analysis of the selection effects present in Anglo-Australian Planet Search data, including the methodology used and some preliminary results.

  8. Direct imaging of extra-solar planets

    Energy Technology Data Exchange (ETDEWEB)

    Olivier, S.S.; Max, V.E.; Brase, J.M.; Caffano, C.J.; Gavel, D.T.; Macintosh, B.A.

    1997-03-01

    Direct imaging of extra-solar planets may be possible with the new generation of large ground-based telescopes equipped with state- of- the-art adaptive optics (AO) systems to compensate for the blurring effect of the Earth`s atmosphere. The first of these systems is scheduled to begin operation in 1998 on the 10 in Keck II telescope. In this paper, general formulas for high-contrast imaging with AO systems are presented and used to calculate the sensitivity of the Keck AO system. The results of these calculations show that the Keck AO system should achieve the sensitivity necessary to detect giant planets around several nearby bright stars.

  9. The HARPS search for southern extra-solar planets. XL. Searching for Neptunes around metal-poor stars

    Science.gov (United States)

    Faria, J. P.; Santos, N. C.; Figueira, P.; Mortier, A.; Dumusque, X.; Boisse, I.; Lo Curto, G.; Lovis, C.; Mayor, M.; Melo, C.; Pepe, F.; Queloz, D.; Santerne, A.; Ségransan, D.; Sousa, S. G.; Sozzetti, A.; Udry, S.

    2016-05-01

    Context. As a probe of the metallicity of proto-planetary disks, stellar metallicity is an important ingredient for giant planet formation, most likely through its effect on the timescales in which rocky or icy planet cores can form. Giant planets have been found to be more frequent around metal-rich stars, in agreement with predictions based on the core-accretion theory. In the metal-poor regime, however, the frequency of planets, especially low-mass planets, and the way it depends on metallicity are still largely unknown. Aims: As part of a planet search programme focused on metal-poor stars, we study the targets from this survey that were observed with HARPS on more than 75 nights. The main goals are to assess the presence of low-mass planets and provide a first estimate of the frequency of Neptunes and super-Earths around metal-poor stars. Methods: We performed a systematic search for planetary companions, both by analysing the periodograms of the radial-velocities and by comparing, in a statistically meaningful way, models with an increasing number of Keplerians. Results: A first constraint on the frequency of planets in our metal-poor sample is calculated considering the previous detection (in our sample) of a Neptune-sized planet around HD 175607 and one candidate planet (with an orbital period of 68.42 d and minimum mass Mpsini = 11.14 ± 2.47 M⊕) for HD 87838, announced in the present study. This frequency is determined to be close to 13% and is compared with results for solar-metallicity stars. Based on observations collected at ESO facilities under programs 082.C-0212, 085.C-0063, 086.C-0284, and 190.C-0027 (with the HARPS spectrograph at the ESO 3.6-m telescope, La Silla-Paranal Observatory).

  10. Empirical study of simulated two-planet microlensing events

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Wei; Gould, Andrew; Penny, Matthew [Department of Astronomy, The Ohio State University, 140 West 18th Avenue, Columbus, OH 43210 (United States); Mao, Shude [National Astronomical Observatories, Chinese Academy of Sciences, 20A Datun Road, Chaoyang District, Beijing 100012 (China); Gendron, Rieul, E-mail: weizhu@astronomy.ohio-state.edu [Jodrell Bank Centre for Astrophysics, University of Manchester, Alan Turing Building, Manchester M13 9PL (United Kingdom)

    2014-10-10

    We undertake the first study of two-planet microlensing models recovered from simulations of microlensing events generated by realistic multiplanet systems in which 292 planetary events, including 16 two-planet events, were detected from 6690 simulated light curves. We find that when two planets are recovered, their parameters are usually close to those of the two planets in the system most responsible for the perturbations. However, in 1 of the 16 examples, the apparent mass of both detected planets was more than doubled by the unmodeled influence of a third, massive planet. This fraction is larger than but statistically consistent with the roughly 1.5% rate of serious mass errors due to unmodeled planetary companions for the 274 cases from the same simulation in which a single planet is recovered. We conjecture that an analogous effect due to unmodeled stellar companions may occur more frequently. For 7 out of 23 cases in which two planets in the system would have been detected separately, only one planet was recovered because the perturbations due to the two planets had similar forms. This is a small fraction (7/274) of all recovered single-planet models, but almost a third of all events that might plausibly have led to two-planet models. Still, in these cases, the recovered planet tends to have parameters similar to one of the two real planets most responsible for the anomaly.

  11. Precisely measuring the density of small transiting exoplanets with particular emphasis on longer period planet using the HARPS-N spectrograph

    Science.gov (United States)

    Buchhave, Lars A.

    2015-08-01

    The majority of exoplanets discovered by the Kepler Mission have sizes that range between 1-4 Earth radii, populating a regime of planets with no Solar System analogues. This regime is critical for understanding the frequency of potentially habitable worlds and to help inform planet formation theories, because it contains the transition from lower-density planets with extended H/He envelopes to higher-density rocky planets with compact atmospheres. HARPS-N is an ultra-stable high-resolution spectrograph optimized for the measurement of precise radial velocities, yielding precise planetary masses and thus densities of small transiting exoplanets. In this talk, I will review the progress to populate the mass-radius parameter space with precisely measured densities of small planets. I will in particular focus on the latest HARPS-N results and their implication for our understanding of these super-Earth and small Neptune type planets.Additionally, I will discuss our progress to measure the masses of longer period sub-Neptune sized planets. In Buchhave el al. 2014, we found suggestive observational evidence that the transition from rocky to gaseous planets might depend on the orbital period, such that larger planets further away from their host star could be massive planets without a large gaseous envelope. To test this hypothesis, we have used HARPS-N to observe longer period planet candidates to determine whether they are in fact massive rocky planets or if they have extended H/He envelopes and thus lower bulk densities.HARPS-N at the Telescopio Nazionale Galileo, La Palma is an international collaboration and was funded by the Swiss Space Office, the Harvard Origin of Life Initiative, the Scottish Universities Physics Alliance, the University of Geneva, the Smithsonian Astrophysical Observatory, and the Italian National Astrophysical Institute, University of St. Andrews, Queens University Belfast, and University of Edinburgh.

  12. THE LAST STAGES OF TERRESTRIAL PLANET FORMATION: DYNAMICAL FRICTION AND THE LATE VENEER

    Energy Technology Data Exchange (ETDEWEB)

    Schlichting, Hilke E.; Warren, Paul H. [UCLA, Department of Earth and Space Science, 595 Charles E. Young Drive East, Los Angeles, CA 90095 (United States); Yin Qingzhu, E-mail: hilke@ucla.edu [UCD, Department of Geology, One Shields Avenue, Davis, CA 95616 (United States)

    2012-06-10

    The final stage of terrestrial planet formation consists of the clean-up of residual planetesimals after the giant impact phase. Dynamically, a residual planetesimal population is needed to damp the high eccentricities and inclinations of the terrestrial planets to circular and coplanar orbits after the giant impact stage. Geochemically, highly siderophile element (HSE) abundance patterns inferred for the terrestrial planets and the Moon suggest that a total of about 0.01 M{sub Circled-Plus} of chondritic material was delivered as 'late veneer' by planetesimals to the terrestrial planets after the end of giant impacts. Here, we combine these two independent lines of evidence for a leftover population of planetesimals and show that: (1) a residual population of small planetesimals containing 0.01 M{sub Circled-Plus} is able to damp the high eccentricities and inclinations of the terrestrial planets after giant impacts to their observed values. (2) At the same time, this planetesimal population can account for the observed relative amounts of late veneer added to the Earth, Moon, and Mars provided that the majority of the accreted late veneer was delivered by small planetesimals with radii {approx}< 10 m. These small planetesimal sizes are required to ensure efficient damping of the planetesimal's velocity dispersion by mutual collisions, which in turn ensures sufficiently low relative velocities between the terrestrial planets and the planetesimals such that the planets' accretion cross sections are significantly enhanced by gravitational focusing above their geometric values. Specifically, we find that, in the limit that the relative velocity between the terrestrial planets and the planetesimals is significantly less than the terrestrial planets' escape velocities, gravitational focusing yields a mass accretion ratio of Earth/Mars {approx}({rho}{sub Circled-Plus }/{rho}{sub mars})(R{sub Circled-Plus }/R{sub mars}){sup 4} {approx} 17, which

  13. Speckle Imaging and Spectroscopy of Kepler Exo-planet Transit Candidate Stars

    Science.gov (United States)

    Howell, Steve B.; Sherry, William; Horch, Elliott; Doyle, Laurance

    2010-02-01

    The NASA Kepler mission was successfully launched on 6 March 2009 and has begun science operations. Commissioning tests done early on in the mission have shown that for the bright sources, 10-15 ppm relative photometry can be achieved. This level assures we will detect Earth- like transits if they are present. ``Hot Jupiter" and similar large planet candidates have already been discovered and will be discussed at the Jan. AAS meeting as well as in a special issue of Science magazine to appear near years end. The plethora of variability observed is astounding and includes a number of eclipsing binaries which appear to have Jupiter and smaller size objects as an orbiting their body. Our proposal consists of three highly related objectives: 1) To continue our highly successful speckle imaging program which is a major component of defense to weed out false positive candidate transiting planets found by Kepler and move the rest to probable or certain exo-planet detections; 2) To obtain low resolution ``discovery" type spectra for planet candidate stars in order to provide spectral type and luminosity class indicators as well as a first look triage to eliminate binaries and rapid rotators; and 3) to obtain ~1Aresolution time ordered spectra of eclipsing binaries that are exo-planet candidates in order to obtain the velocity solution for the binary star, allowing its signal to be modeled and removed from the Keck or HET exo-planet velocity search. As of this writing, Kepler has produced a list of 227 exo-planet candidates which require false positive decision tree observations. Our proposed effort performs much of the first line of defense for the mission.

  14. Validation of small Kepler transiting planet candidates in or near the habitable zone

    DEFF Research Database (Denmark)

    Torres, Guillermo; Kane, Stephen R.; Rowe, Jason F.

    2017-01-01

    A main goal of NASA's Kepler Mission is to establish the frequency of potentially habitable Earth-size planets (). Relatively few such candidates identified by the mission can be confirmed to be rocky via dynamical measurement of their mass. Here we report an effort to validate 18 of them...... statistically using the BLENDER technique, by showing that the likelihood they are true planets is far greater than that of a false positive. Our analysis incorporates follow-up observations including high-resolution optical and near-infrared spectroscopy, high-resolution imaging, and information from...... the analysis of the flux centroids of the Kepler observations themselves. Although many of these candidates have been previously validated by others, the confidence levels reported typically ignore the possibility that the planet may transit a star different from the target along the same line of sight...

  15. Observations at the planet Mercury by the plasma electron experiment, Mariner 10

    Science.gov (United States)

    Ogilvie, K. W.; Scudder, J. D.; Vasyliunas, V. M.; Hartle, R. E.; Siscoe, G. L.

    1976-01-01

    Plasma electron observations made onboard Mariner 10 are reported. Three encounters with the planet Mercury show that the planet interacts with the solar wind to form a bow shock and a permanent magnetosphere. The observations provide a determination of the dimensions and properties of the magnetosphere, independently of and in general agreement with magnetometer observations. The magnetosphere of Mercury appears to be similar in shape to that of the Earth but much smaller in relation to the size of the planet. Electron populations similar to those found in the Earth's magnetotail, within the plasma sheet and adjacent regions, were observed at Mercury; both their spatial location and the electron energy spectra within them bear qualitative and quantitative resemblance to corresponding observations at the Earth. The magnetosphere of Mercury resembles to a marked degree a reduced version of that of the Earth, with no significant differences of structure.

  16. Atmospheric escape from the TRAPPIST-1 planets and implications for habitability.

    Science.gov (United States)

    Dong, Chuanfei; Jin, Meng; Lingam, Manasvi; Airapetian, Vladimir S; Ma, Yingjuan; van der Holst, Bart

    2018-01-09

    The presence of an atmosphere over sufficiently long timescales is widely perceived as one of the most prominent criteria associated with planetary surface habitability. We address the crucial question of whether the seven Earth-sized planets transiting the recently discovered ultracool dwarf star TRAPPIST-1 are capable of retaining their atmospheres. To this effect, we carry out numerical simulations to characterize the stellar wind of TRAPPIST-1 and the atmospheric ion escape rates for all of the seven planets. We also estimate the escape rates analytically and demonstrate that they are in good agreement with the numerical results. We conclude that the outer planets of the TRAPPIST-1 system are capable of retaining their atmospheres over billion-year timescales. The consequences arising from our results are also explored in the context of abiogenesis, biodiversity, and searches for future exoplanets. In light of the many unknowns and assumptions involved, we recommend that these conclusions must be interpreted with due caution.

  17. Post main sequence evolution of icy minor planets: water retention and white dwarf pollution

    Science.gov (United States)

    Malamud, Uri; Perets, Hagai

    2017-06-01

    We investigate the evolution of icy minor planets from the moment of their birth and through the all evolutionary stages of their host stars, including the main sequence, red giant branch and asymptotic giant branch phases. We then asses the degree of water retention in planetary systems around white dwarf, as a function of various parameters. We consider progenitor stars of different masses and metallicities. We also consider minor planets of various sizes, initial orbital distances, compositions and formation times. Our results indicate that water can survive to the white dwarf stage in a variety of circumstances, especially around G, F, A and even some B type stars. We discuss the significance of water retention with respect to white dwarf pollution and also for planet habitability.

  18. Positioning and applications for planet earth

    NARCIS (Netherlands)

    Verhagen, S.; Retscher, G.; Santos, M.C.; Ding, X.L.; Gao, Y.; Jin, S.G.

    2009-01-01

    GNSS, InSAR and LIDAR are identified as important techniques when it comes to monitoring and remote sensing of our planet Earth and its atmosphere. In fact, these techniques can be considered as key elements of the Global Geodetic Observing System. Examples of applications are: environmental

  19. Polarization Spectra of Extrasolar Giant Planets

    NARCIS (Netherlands)

    Stam, D.M.

    2004-01-01

    We present simulated spectra of the flux and degree of polarization of starlight that is reflected by extrasolar giant planets (EGPs). In particular the polarization depends strongly on the structure of the planetary atmosphere, and appears to be a valuable tool for the characterization of EGPs.

  20. How photos of planets reach the earth

    Directory of Open Access Journals (Sweden)

    C. Roos

    1983-03-01

    Full Text Available The way in which photos of planets are transmitted to the earth is discussed. Problems that may arise during transmission are mentioned and a method to detect and correct errors is discussed. This is a survey article and the aim was not to give a rigorous mathematical explanation.

  1. Abiotic production of methane in terrestrial planets.

    Science.gov (United States)

    Guzmán-Marmolejo, Andrés; Segura, Antígona; Escobar-Briones, Elva

    2013-06-01

    On Earth, methane is produced mainly by life, and it has been proposed that, under certain conditions, methane detected in an exoplanetary spectrum may be considered a biosignature. Here, we estimate how much methane may be produced in hydrothermal vent systems by serpentinization, its main geological source, using the kinetic properties of the main reactions involved in methane production by serpentinization. Hydrogen production by serpentinization was calculated as a function of the available FeO in the crust, given the current spreading rates. Carbon dioxide is the limiting reactant for methane formation because it is highly depleted in aqueous form in hydrothermal vent systems. We estimated maximum CH4 surface fluxes of 6.8×10(8) and 1.3×10(9) molecules cm(-2) s(-1) for rocky planets with 1 and 5 M⊕, respectively. Using a 1-D photochemical model, we simulated atmospheres with volume mixing ratios of 0.03 and 0.1 CO2 to calculate atmospheric methane concentrations for the maximum production of this compound by serpentinization. The resulting abundances were 2.5 and 2.1 ppmv for 1 M⊕ planets and 4.1 and 3.7 ppmv for 5 M⊕ planets. Therefore, low atmospheric concentrations of methane may be produced by serpentinization. For habitable planets around Sun-like stars with N2-CO2 atmospheres, methane concentrations larger than 10 ppmv may indicate the presence of life.

  2. Detection and characterization of extrasolar planets

    Directory of Open Access Journals (Sweden)

    Ferlet R.

    2009-02-01

    Full Text Available The main methods to detect planets orbiting stars other than our Sun are briefly described, together with their present results. Some characteristics of the known systems are emphasized. Particularly interesting are the transiting exoplanets which allow to reveal their atmospheres and ultimately identify biosignatures.

  3. The magnetospheres of the outer planets

    Energy Technology Data Exchange (ETDEWEB)

    Mcnutt, R.L., Jr. (USAF, Geophysics Laboratory, Hanscom AFB, MA (United States))

    1991-01-01

    Research on the magnetospheres of all of the outer planets including Jupiter, Uranus, Neptune, and Pluto is reviewed for the 1987-1990 time period. Particular attention is given to magnetospheric structure, plasma transport, Jovian aurora, Io and the plasma torus, Titan and its magnetospheric interactions, rings and dusty plasmas, magnetospheric convection, and satellite interactions.

  4. Finding Terrestrial Planets Using External Occulters

    Science.gov (United States)

    Heap, Sara

    2007-01-01

    In order to identify a detected exoplanet as an Earth-like (habitable) planet, we must obtain its spectrum to verify that its atmosphere shows evidence of water vapor. We argue that a regular, optical telescope combined with a large occulter to block light from the star offers the most promising, cost-effective way to detect and characterize exoplanets.

  5. Climate model studies of synchronously rotating planets.

    Science.gov (United States)

    Joshi, Manoj

    2003-01-01

    M stars constitute 75% of main sequence stars though, until recently, their star systems have not been considered suitable places for habitable planets to exist. In this study the climate of a synchronously rotating planet around an M dwarf star is evaluated using a three-dimensional global atmospheric circulation model. The presence of clouds and evaporative cooling at the surface of the planet result in a cooler surface temperature at the subsolar point. Water ice forms at the polar regions and on the dark side, where the minimum temperature lies between -30 degrees C and 0 degrees C. As expected, rainfall is extremely high on the starlit side and extremely low on the dark side. The presence of a dry continent causes higher temperatures on the dayside, and allows accumulation of snow on the nightside. The absence of any oceans leads to higher day-night temperature differences, consistent with previous work. The present study reinforces recent conclusions that synchronously rotating planets within the circumstellar habitable zones of M dwarf stars should be habitable, and therefore M dwarf systems should not be excluded in future searches for exoplanets.

  6. THE CALIFORNIA PLANET SURVEY IV: A PLANET ORBITING THE GIANT STAR HD 145934 AND UPDATES TO SEVEN SYSTEMS WITH LONG-PERIOD PLANETS

    Energy Technology Data Exchange (ETDEWEB)

    Katherina Feng, Y.; Wright, Jason T.; Nelson, Benjamin; Wang, Sharon X.; Ford, Eric B. [Center for Exoplanets and Habitable Worlds, Department of Astronomy and Astrophysics, 525 Davey Lab, The Pennsylvania State University, University Park, PA 16802 (United States); Marcy, Geoffrey W.; Isaacson, Howard [Department of Astronomy, University of California, Berkeley, CA 94720-3411 (United States); Howard, Andrew W., E-mail: astrowright@gmail.com [Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI 96822 (United States)

    2015-02-10

    We present an update to seven stars with long-period planets or planetary candidates using new and archival radial velocities from Keck-HIRES and literature velocities from other telescopes. Our updated analysis better constrains orbital parameters for these planets, four of which are known multi-planet systems. HD 24040 b and HD 183263 c are super-Jupiters with circular orbits and periods longer than 8 yr. We present a previously unseen linear trend in the residuals of HD 66428 indicative of an additional planetary companion. We confirm that GJ 849 is a multi-planet system and find a good orbital solution for the c component: it is a 1 M {sub Jup} planet in a 15 yr orbit (the longest known for a planet orbiting an M dwarf). We update the HD 74156 double-planet system. We also announce the detection of HD 145934 b, a 2 M {sub Jup} planet in a 7.5 yr orbit around a giant star. Two of our stars, HD 187123 and HD 217107, at present host the only known examples of systems comprising a hot Jupiter and a planet with a well constrained period greater than 5 yr, and with no evidence of giant planets in between. Our enlargement and improvement of long-period planet parameters will aid future analysis of origins, diversity, and evolution of planetary systems.

  7. Planck intermediate results. LII. Planet flux densities

    Science.gov (United States)

    Planck Collaboration; Akrami, Y.; Ashdown, M.; Aumont, J.; Baccigalupi, C.; Ballardini, M.; Banday, A. J.; Barreiro, R. B.; Bartolo, N.; Basak, S.; Benabed, K.; Bernard, J.-P.; Bersanelli, M.; Bielewicz, P.; Bonavera, L.; Bond, J. R.; Borrill, J.; Bouchet, F. R.; Boulanger, F.; Bucher, M.; Burigana, C.; Butler, R. C.; Calabrese, E.; Cardoso, J.-F.; Carron, J.; Chiang, H. C.; Colombo, L. P. L.; Comis, B.; Couchot, F.; Coulais, A.; Crill, B. P.; Curto, A.; Cuttaia, F.; de Bernardis, P.; de Rosa, A.; de Zotti, G.; Delabrouille, J.; Di Valentino, E.; Dickinson, C.; Diego, J. M.; Doré, O.; Ducout, A.; Dupac, X.; Elsner, F.; Enßlin, T. A.; Eriksen, H. K.; Falgarone, E.; Fantaye, Y.; Finelli, F.; Frailis, M.; Fraisse, A. A.; Franceschi, E.; Frolov, A.; Galeotta, S.; Galli, S.; Ganga, K.; Génova-Santos, R. T.; Gerbino, M.; González-Nuevo, J.; Górski, K. M.; Gruppuso, A.; Gudmundsson, J. E.; Hansen, F. K.; Helou, G.; Henrot-Versillé, S.; Herranz, D.; Hivon, E.; Jaffe, A. H.; Jones, W. C.; Keihänen, E.; Keskitalo, R.; Kiiveri, K.; Kim, J.; Kisner, T. S.; Krachmalnicoff, N.; Kunz, M.; Kurki-Suonio, H.; Lagache, G.; Lamarre, J.-M.; Lasenby, A.; Lattanzi, M.; Lawrence, C. R.; Le Jeune, M.; Lellouch, E.; Levrier, F.; Liguori, M.; Lilje, P. B.; Lindholm, V.; López-Caniego, M.; Ma, Y.-Z.; Macías-Pérez, J. F.; Maggio, G.; Maino, D.; Mandolesi, N.; Maris, M.; Martin, P. G.; Martínez-González, E.; Matarrese, S.; Mauri, N.; McEwen, J. D.; Melchiorri, A.; Mennella, A.; Migliaccio, M.; Miville-Deschênes, M.-A.; Molinari, D.; Moneti, A.; Montier, L.; Moreno, R.; Morgante, G.; Natoli, P.; Oxborrow, C. A.; Paoletti, D.; Partridge, B.; Patanchon, G.; Patrizii, L.; Perdereau, O.; Piacentini, F.; Plaszczynski, S.; Polenta, G.; Rachen, J. P.; Racine, B.; Reinecke, M.; Remazeilles, M.; Renzi, A.; Rocha, G.; Romelli, E.; Rosset, C.; Roudier, G.; Rubiño-Martín, J. A.; Ruiz-Granados, B.; Salvati, L.; Sandri, M.; Savelainen, M.; Scott, D.; Sirri, G.; Spencer, L. D.; Suur-Uski, A.-S.; Tauber, J. A.; Tavagnacco, D.; Tenti, M.; Toffolatti, L.; Tomasi, M.; Tristram, M.; Trombetti, T.; Valiviita, J.; Van Tent, F.; Vielva, P.; Villa, F.; Wehus, I. K.; Zacchei, A.

    2017-11-01

    Measurements of flux density are described for five planets, Mars, Jupiter, Saturn, Uranus, and Neptune, across the six Planck High Frequency Instrument frequency bands (100-857 GHz) and these are then compared with models and existing data. In our analysis, we have also included estimates of the brightness of Jupiter and Saturn at the three frequencies of the Planck Low Frequency Instrument (30, 44, and 70 GHz). The results provide constraints on the intrinsic brightness and the brightness time-variability of these planets. The majority of the planet flux density estimates are limited by systematic errors, but still yield better than 1% measurements in many cases. Applying data from Planck HFI, the Wilkinson Microwave Anisotropy Probe (WMAP), and the Atacama Cosmology Telescope (ACT) to a model that incorporates contributions from Saturn's rings to the planet's total flux density suggests a best fit value for the spectral index of Saturn's ring system of βring = 2.30 ± 0.03 over the 30-1000 GHz frequency range. Estimates of the polarization amplitude of the planets have also been made in the four bands that have polarization-sensitive detectors (100-353 GHz); this analysis provides a 95% confidence level upper limit on Mars's polarization of 1.8, 1.7, 1.2, and 1.7% at 100, 143, 217, and 353 GHz, respectively. The average ratio between the Planck-HFI measurements and the adopted model predictions for all five planets (excluding Jupiter observations for 353 GHz) is 1.004, 1.002, 1.021, and 1.033 for 100, 143, 217, and 353 GHz, respectively. Model predictions for planet thermodynamic temperatures are therefore consistent with the absolute calibration of Planck-HFI detectors at about the three-percent level. We compare our measurements with published results from recent cosmic microwave background experiments. In particular, we observe that the flux densities measured by Planck HFI and WMAP agree to within 2%. These results allow experiments operating in the mm

  8. Planet Detectability in the Alpha Centauri System

    Science.gov (United States)

    Zhao, Lily; Fischer, Debra A.; Brewer, John; Giguere, Matt; Rojas-Ayala, Bárbara

    2018-01-01

    We use more than a decade of radial-velocity measurements for α {Cen} A, B, and Proxima Centauri from the High Accuracy Radial Velocity Planet Searcher, CTIO High Resolution Spectrograph, and the Ultraviolet and Visual Echelle Spectrograph to identify the M\\sin i and orbital periods of planets that could have been detected if they existed. At each point in a mass–period grid, we sample a simulated, Keplerian signal with the precision and cadence of existing data and assess the probability that the signal could have been produced by noise alone. Existing data places detection thresholds in the classically defined habitable zones at about M\\sin i of 53 {M}\\oplus for α {Cen} A, 8.4 {M}\\oplus for α {Cen} B, and 0.47 {M}\\oplus for Proxima Centauri. Additionally, we examine the impact of systematic errors, or “red noise” in the data. A comparison of white- and red-noise simulations highlights quasi-periodic variability in the radial velocities that may be caused by systematic errors, photospheric velocity signals, or planetary signals. For example, the red-noise simulations show a peak above white-noise simulations at the period of Proxima Centauri b. We also carry out a spectroscopic analysis of the chemical composition of the α {Centauri} stars. The stars have super-solar metallicity with ratios of C/O and Mg/Si that are similar to the Sun, suggesting that any small planets in the α {Cen} system may be compositionally similar to our terrestrial planets. Although the small projected separation of α {Cen} A and B currently hampers extreme-precision radial-velocity measurements, the angular separation is now increasing. By 2019, α {Cen} A and B will be ideal targets for renewed Doppler planet surveys.

  9. Dynamical Evolution Induced by Planet Nine

    Science.gov (United States)

    Batygin, Konstantin; Morbidelli, Alessandro

    2017-12-01

    The observational census of trans-Neptunian objects with semimajor axes greater than ˜ 250 {au} exhibits unexpected orbital structure that is most readily attributed to gravitational perturbations induced by a yet-undetected, massive planet. Although the capacity of this planet to (I) reproduce the observed clustering of distant orbits in physical space, (II) facilitate the dynamical detachment of their perihelia from Neptune, and (III) excite a population of long-period centaurs to extreme inclinations is well-established through numerical experiments, a coherent theoretical description of the dynamical mechanisms responsible for these effects remains elusive. In this work, we characterize the dynamical processes at play from semi-analytic grounds. We begin by considering a purely secular model of orbital evolution induced by Planet Nine and show that it is at odds with the ensuing stability of distant objects. Instead, the long-term survival of the clustered population of long-period Kuiper Belt objects (KBOs) is enabled by a web of mean-motion resonances driven by Planet Nine. Then, by taking a compact-form approach to perturbation theory, we show that it is the secular dynamics embedded within these resonances that regulate the orbital confinement and perihelion detachment of distant KBOs. Finally, we demonstrate that the onset of large-amplitude oscillations of the orbital inclinations is accomplished through the capture of low-inclination objects into a high-order secular resonance, and we identify the specific harmonic that drives the evolution. In light of the developed qualitative understanding of the governing dynamics, we offer an updated interpretation of the current observational data set within the broader theoretical framework of the Planet Nine hypothesis.

  10. Noble gases in meteorites and terrestrial planets

    Science.gov (United States)

    Wacker, J. F.

    1985-01-01

    Terrestrial planets and chondrites have noble gas platforms that are sufficiently alike, especially Ne/Ar, that they may have acquired their noble gases by similar processes. Meteorites presumably obtained their noble gases during formation in the solar nebula. Adsorption onto C - the major gas carrier in chondrites - is the likely mechanism for trapping noble gases; recent laboratory simulations support this hypothesis. The story is more complex for planets. An attractive possibility is that the planets acquired their noble gases in a late accreting veneer of chondritic material. In chondrites, noble gases correlate with C, N, H, and volatile metals; by Occam's Razor, we would expect a similar coupling in planets. Indeed, the Earth's crust and mantle contain chondritic like trace volatiles and PL group metals, respectively and the Earth's oceans resemble C chondrites in their enrichment of D (8X vs 8-10X of the galactic D/H ratio). Models have been proposed to explain some of the specific noble gas patterns in planets. These include: (1) noble gases may have been directly trapped by preplanetary material instead of arriving in a veneer; (2) for Venus, irradiation of preplanetary material, followed by diffusive loss of Ne, could explain the high concentration of AR-36; (3) the Earth and Venus may have initially had similar abundances of noble gases, but the Earth lost its share during the Moon forming event; (4) noble gases could have been captured by planetestimals, possibly leading to gravitational fractionation, particularly of Xe isotopes and (5) noble gases may have been dissolved in the hot outer portion of the Earth during contact with a primordial atmosphere.

  11. Red Optical Planet Survey: A radial velocity search for low mass M dwarf planets

    Directory of Open Access Journals (Sweden)

    Minniti D.

    2013-04-01

    Full Text Available We present radial velocity results from our Red Optical Planet Survey (ROPS, aimed at detecting low-mass planets orbiting mid-late M dwarfs. The ∼10 ms−1 precision achieved over 2 consecutive nights with the MIKE spectrograph at Magellan Clay is also found on week long timescales with UVES at VLT. Since we find that UVES is expected to attain photon limited precision of order 2 ms−1 using our novel deconvolution technique, we are limited only by the (≤10 ms−1 stability of atmospheric lines. Rocky planet frequencies of η⊕ = 0.3−0.7 lead us to expect high planet yields, enabling determination of η⊕ for the uncharted mid-late M dwarfs with modest surveys.

  12. Detecting Extrasolar Planets With Millimeter-Wave Observatories

    Science.gov (United States)

    1996-01-01

    Do nearby stars have planetary systems like our own? How do such systems evolve? How common are such systems? Proposed radio observatories operating at millimeter wavelengths could start answering these questions within the next 6-10 years, according to scientists at the National Radio Astronomy Observatory (NRAO). Bryan Butler, Robert Brown, Richard Simon, Al Wootten and Darrel Emerson, all of NRAO, presented their findings today to the American Astronomical Society meeting in San Antonio, TX. Detecting planets circling other stars is a particularly difficult task, and only a few such planets have been discovered so far. In order to answer fundamental questions about planetary systems and their origin, scientists need to find and study many more extrasolar planets. According to the NRAO scientists, millimeter-wavelength observatories could provide valuable information about extrasolar planetary systems at all stages of their evolution. "With instruments planned by 2005, we could detect planets the size of Jupiter around a solar-type star out to a distance of 100 light-years," said Robert Brown, Associate Director of NRAO. "That means," he added, "that we could survey approximately 2,000 stars of different types to learn if they have planets this size." Millimeter waves occupy the portion of the electromagnetic spectrum between radio microwaves and infrared waves. Telescopes for observing at millimeter wavelengths utilize advanced electronic equipment similar to that used in radio telescopes observing at longer wavelengths. Millimeter-wave observatories offer a number of advantages in the search for extrasolar planets. Planned multi-antenna millimeter-wave telescopes can provide much higher resolving power, or ability to see fine detail, than current optical or infrared telescopes. Millimeter-wave observations would not be degraded by interference from the "zodiacal light" reflected by interplanetary dust, either in the extrasolar system or our own solar system

  13. Early Giant Planet Candidates from the SDSS-III MARVELS Planet Survey

    Science.gov (United States)

    Thomas, Neil; Ge, J.; Li, R.; Sithajan, S.; Chen, Y.; Shi, J.; Ma, B.; Liu, J.

    2014-01-01

    We report the first discoveries of giant planet candidates from the SDSS-III MARVELS survey. These candidates are found using the new MARVELS data pipeline developed at UF from scratch over the past two years. Unlike the old data pipeline, this pipeline carefully corrects most of the instrument effects (such as trace, slant, distortion, drifts and dispersion) and observation condition effects (such as illumination profile). The result is long-term RV precisions that approach the photon limits in many cases and has yielded four giant planet candidates of ~1-6 Jupiter mass from only the initial fraction of data processed with the new techniques. More survey data is being processed which will likely lead to discoveries of additional giant planet candidates that will be verified and characterized with follow-up observations by the MARVELS team. The MARVELS survey has produced the largest homogeneous RV measurements of 3300 V=7.6-12 FGK stars with well defined cadence 27 RV measurements over 2 years). The MARVELS RV data and other follow-up data (photometry, high contrast imaging, high resolution spectroscopy and RV measurements) will explore the diversity of giant planet companion formation and evolution around stars with a broad range in metallicity ([Fe/H -1.5-0.5), mass ( 0.6-2.5M(sun)), and environment (thin disk and thick disk), and will help to address the key scientific questions identified for the MARVELS survey including, but not limited to: Do metal poor stars obey the same trends for planet occurrence as metal rich stars? What is the distribution of giant planets around intermediate-mass stars and binaries? Is the “planet desert” within 0.6 AU in the planet orbital distribution of intermediate-mass stars real?

  14. Terrestrial Planet Finder Coronagraph High Accuracy Optical Propagation Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The Terrestrial Planet Finder (TPF) project is considering several approaches to discovering planets orbiting stars far from earth and assessing their suitability to...

  15. Stars rich in heavy metals tend to harbor planets

    CERN Multimedia

    2003-01-01

    "A comparison of 754 nearby stars like our Sun - some with planets and some without - shows definitively that the more iron and other metals there are in a star, the greater the chance it has a companion planet" (1 page).

  16. Probing Planet Formation with APOGEE: A Dichotomy in Planet Orbital-Periods and Stellar Metallicities

    Science.gov (United States)

    Wilson, Robert Forrest; Teske, Johanna; Majewski, Steven R.; Cunha, Katia; Smith, Verne; Souto, Diogo; Bender, Chad; Mahadevan, Suvrath; Troup, Nicholas; ALLENDE PRIETO, CARLOS; Stassun, Keivan G.; Skrutskie, Michael; ALMEIDA, ANDRES; Brinkmann, Jonathan; APOGEE

    2018-01-01

    The Apache Point Observatory Galactic Evolution Experiment (APOGEE) is a near-infrared (1.5-1.7 microns), high resolution (R~22,500), high S/N (>100), spectroscopic survey as part of the Sloan Digital Sky Survey (SDSS). Among the goals of this survey is multi-epoch monitoring of exoplanetary systems discovered by the Kepler mission, resulting in very high S/N (typically a few hundred) observations of Planet-hosting stars. The combined visits and sensitivity of the Sloan 2.5-meter telescope yield stellar parameters for a large number of planet-hosting systems with higher precision (e.g., $\\sigma_{[Fe/H]} earth) exoplanetary systems. In particular, we find that planets with orbital periods P ≤ 8.5 days have statistically more metal-enriched hosts than planets with P > 8.5 days. This dichotomy implies that there may be different formation histories between these two populations. For example, there may be a protoplanetary disk inner-radius (such as the gas co-rotation radius or the dust-sublimation radius) with a metallicity-dependence at the time of planet formation that allows small, rocky planets to either form or migrate closer in to their host star in metal-rich conditions. In addition, based on previous work about the "Evaporation Valley", there is theoretical support that this critical period of 8.5 days may be tied to the bulk composition of the two exoplanet populations.

  17. Terrestrial planet formation in a protoplanetary disk with a local mass depletion: A successful scenario for the formation of Mars

    Energy Technology Data Exchange (ETDEWEB)

    Izidoro, A.; Winter, O. C. [UNESP, Univ. Estadual Paulista - Grupo de Dinâmica Orbital and Planetologia, Guaratinguetá, CEP 12.516-410, São Paulo (Brazil); Haghighipour, N. [Institute for Astronomy and NASA Astrobiology Institute, University of Hawaii-Manoa, Honolulu, HI 96822 (United States); Tsuchida, M., E-mail: izidoro@feg.unesp.br, E-mail: nader@ifa.hawaii.edu [UNESP, Univ. Estadual Paulista, DCCE-IBILCE, São José do Rio Preto, CEP 15.054-000, São Paulo (Brazil)

    2014-02-10

    Models of terrestrial planet formation for our solar system have been successful in producing planets with masses and orbits similar to those of Venus and Earth. However, these models have generally failed to produce Mars-sized objects around 1.5 AU. The body that is usually formed around Mars' semimajor axis is, in general, much more massive than Mars. Only when Jupiter and Saturn are assumed to have initially very eccentric orbits (e ∼ 0.1), which seems fairly unlikely for the solar system, or alternately, if the protoplanetary disk is truncated at 1.0 AU, simulations have been able to produce Mars-like bodies in the correct location. In this paper, we examine an alternative scenario for the formation of Mars in which a local depletion in the density of the protosolar nebula results in a non-uniform formation of planetary embryos and ultimately the formation of Mars-sized planets around 1.5 AU. We have carried out extensive numerical simulations of the formation of terrestrial planets in such a disk for different scales of the local density depletion, and for different orbital configurations of the giant planets. Our simulations point to the possibility of the formation of Mars-sized bodies around 1.5 AU, specifically when the scale of the disk local mass-depletion is moderately high (50%-75%) and Jupiter and Saturn are initially in their current orbits. In these systems, Mars-analogs are formed from the protoplanetary materials that originate in the regions of disk interior or exterior to the local mass-depletion. Results also indicate that Earth-sized planets can form around 1 AU with a substantial amount of water accreted via primitive water-rich planetesimals and planetary embryos. We present the results of our study and discuss their implications for the formation of terrestrial planets in our solar system.

  18. The interplay between X-ray photoevaporation and planet formation

    OpenAIRE

    Rosotti, Giovanni P.; Ercolano, Barbara; Owen, James. E.; Armitage, Philip J.

    2013-01-01

    We assess the potential of planet formation instigating the early formation of a photoevaporation driven gap, up to radii larger than typical for photoevaporation alone. For our investigation we make use of hydrodynamics models of photoevaporating discs with a giant planet embedded. We find that, by reducing the mass accretion flow onto the star, discs that form giant planets will be dispersed at earlier times than discs without planets by X-ray photoevaporation. By clearing the portion of th...

  19. Implications of the TTV-detection of close-in terrestrial planets around M stars for their origin and dynamical evolution

    Directory of Open Access Journals (Sweden)

    Rastegar S.

    2011-02-01

    Full Text Available It has been shown that an Earth-size planet or a super-Earth, in resonance with a transiting Jupiter-like body around an M star, can create detectable TTV signals (Kirste & Haghighipour, 2011. Given the low masses of M stars and their circumstellar disks, it is expected that the transiting giant planet to have formed at large distances and migrated to its close-in orbit. That implies, the terrestrial planet has to form during the migration of the giant planet, be captured in resonances, and migrate with the giant body to short-period orbits. To determine the possibility of this scenario, we have studied the dynamics of a disk of protoplanetary embryos and the formation of terrestrial planets during the migration of a Jupiter-like planet around an M star. Results suggest that unless the terrestrial planet was also formed at large distances and carried to its close-in resonant orbit by the giant planet, it is unlikely for this object to form in small orbits. We present the details of our simulations and discuss the implication of the results for the origin of the terrestrial planet.

  20. The Gemini Deep Planet Survey - GDPS

    Energy Technology Data Exchange (ETDEWEB)

    Lafreniere, D; Doyon, R; Marois, C; Nadeau, D; Oppenheimer, B R; Roche, P F; Rigaut, F; Graham, J R; Jayawardhana, R; Johnstone, D; Kalas, P G; Macintosh, B; Racine, R

    2007-06-01

    We present the results of the Gemini Deep Planet Survey, a near-infrared adaptive optics search for giant planets and brown dwarfs around nearby young stars. The observations were obtained with the Altair adaptive optics system at the Gemini North telescope and angular differential imaging was used to suppress the speckle noise of the central star. Detection limits for the 85 stars observed are presented, along with a list of all faint point sources detected around them. Typically, the observations are sensitive to angular separations beyond 0.5-inch with 5{sigma} contrast sensitivities in magnitude difference at 1.6 {micro}m of 9.6 at 0.5-inch, 12.9 at 1-inch, 15 at 2-inch, and 16.6 at 5-inch. For the typical target of the survey, a 100 Myr old K0 star located 22 pc from the Sun, the observations are sensitive enough to detect planets more massive than 2 M{sub Jup} with a projected separation in the range 40-200 AU. Depending on the age, spectral type, and distance of the target stars, the minimum mass that could be detected with our observations can be {approx}1 M{sub Jup}. Second epoch observations of 48 stars with candidates (out of 54) have confirmed that all candidates are unrelated background stars. A detailed statistical analysis of the survey results, which provide upper limits on the fractions of stars with giant planet or low mass brown dwarf companions, is presented. Assuming a planet mass distribution dn/dm {proportional_to} m{sup -1.2} and a semi-major axis distribution dn/da {proportional_to} a{sup -1}, the upper limits on the fraction of stars with at least one planet of mass 0.5-13 M{sub Jup} are 0.29 for the range 10-25 AU, 0.13 for 25-50 AU, and 0.09 for 50-250 AU, with a 95% confidence level; this result is weakly dependent on the semi-major axis distribution power-law index. Without making any assumption on the mass and semi-major axis distributions, the fraction of stars with at least one brown dwarf companion having a semi-major axis in the

  1. Pioneering the red planet; adventures on Martian soil

    NARCIS (Netherlands)

    Van der Peijl, I.; Veraart, M.

    2013-01-01

    Mars has always obsessed humankind - the Red planet, the ‘New Earth’. And with the recent successful landing of NASA’s Curiosity rover, Mars is closer than ever. Ever since 1960, we have actively been sending probes and rovers to observe the planet, but not without defeat. The road to the red planet

  2. The science case of the CHEOPS planet finder for VLT

    NARCIS (Netherlands)

    Gratton, R.; Feldt, M.; Schmid, H.M.; Brandner, W.; Hippler, S.; Neuhauser, R.; Quirrenbach, A.; Desidera, S.; Turatto, M.; Stam, D.M.; Hasinger, G.; Turner, M.J.L.

    2004-01-01

    The CHEOPS Planet Finder is one of the proposed second generation instruments for the VLT. Its purpose is to image and characterize giant extrasolar planets in different phases of their evolution: young, warm planets as well as old, cold ones. Imaging the last ones is the most challenging task

  3. Comparative geology of the satellites of the giant planets

    Science.gov (United States)

    Masson, P.

    1984-08-01

    The geologic evolution of the Jovian and Saturnian satellites is reviewed with regard to the major discoveries of the Voyager 1 and 2 encounters with Jupiter and Saturn. Nearly 40 satellites are now identified in the Jovian and Saturnian systems. Three of these satellites (Ganymede, Titan, and Callisto) are larger than Mercury, two (Io and Europa) have sizes similar to the moon, and four others (Rhea, Iapetus, Dione, and Tethys) are larger than the largest asteroids. They all have experienced different geologic evolutions related to their composition and to their location in the two systems. The present emphasis is upon the cratering record of their surfaces, and on their thermal evolution, with regard to the tidal effects produced by the giant planets. The small satellites are presented with no attempt to review their geologic record, since they are only known from their orbital properties.

  4. CoRoT: a first space mission to find terrestrial planets

    Science.gov (United States)

    Barge, P.; Baglin, A.; Auvergne, M.; Buey, J.-T.; Catala, C.; Michel, E.; Weiss, W. W.; Deleuil, M.; Jorda, L.; Moutou, C.; COROT Team

    2005-12-01

    CoRoT is a space mission devoted to broadband star photometry in visible light during long observing runs. Developed by CNES with a wide european cooperation, it will be launched in 2006 with two pionneering scientific programs: star seismology and detection of terrestrial planets. CoRoT will use the transit method looking for terrestrial planets slightly larger than the Earth. It will check the existence (or absence) of big ``hot-terrestrials" and will discover, quite certainly, a large number of close-in giants. Our understanding on the origin and evolution of these ``hot" planets will certainly be greatly improved thanks to the strong sample enlargement and to the possibility to measure the planet mass from Doppler follow-up. We give in this paper a brief overview of the instrument, the satellite and the expected detection capabilities. Planetary radii will be measured down to Uranus size around solar type stars and down to Earth size around M type stars. Orbital periods will be determined up to 75 days.

  5. Compositional constraints on giant planet formation

    Science.gov (United States)

    Owen, Tobias; Encrenaz, Therese

    2006-10-01

    Using Ockham's razor as a guide, we have tried to find the simplest model for the formation of giant planets that can explain current observations of atmospheric composition. While this "top-down" approach is far from sufficient to define such models, it establishes a set of boundary conditions whose satisfaction is necessary. Using Jupiter as the prototype, we find that a simple model for giant planet formation that begins with a solar nebula of uniform composition and relies on accretion of low temperature icy planetesimals plus collapse of surrounding solar nebula gas supplies that satisfaction. We compare the resulting predictions of elemental abundances and isotope ratios in the atmospheres of the other giants with those from contrasting models and suggest some key measurements to make further progress.

  6. Gravitational Microlensing of Earth-mass Planets

    DEFF Research Database (Denmark)

    Harpsøe, Kennet Bomann West

    common such planets are in our galaxy. There are a few other known methods for detecting exoplanets which have very different bias patterns. This thesis has been divided into two parts, treating two of these other methods. Part I is dedicated to the method of gravitational microlensing, a method...... that utilises the lensing effect of light bend in the gravitational of stars to detect perturbations in said gravitational field, which can be caused by bound planets. So far the discovery of 16 exoplanets detected with gravitational microlensing have been published. The discovery rate with this method is low...... because of the lack of dedicated resources for this method, but this will change in the near future with the completion of several global telescope networks like SONG, Korean Microlensing Telescope Network (KMTNet) and the Las Cumbres Global Telescope network. The gravitational microlensing method is also...

  7. Mathematical models and methods for planet Earth

    CERN Document Server

    Locatelli, Ugo; Ruggeri, Tommaso; Strickland, Elisabetta

    2014-01-01

    In 2013 several scientific activities have been devoted to mathematical researches for the study of planet Earth. The current volume presents a selection of the highly topical issues presented at the workshop “Mathematical Models and Methods for Planet Earth”, held in Roma (Italy), in May 2013. The fields of interest span from impacts of dangerous asteroids to the safeguard from space debris, from climatic changes to monitoring geological events, from the study of tumor growth to sociological problems. In all these fields the mathematical studies play a relevant role as a tool for the analysis of specific topics and as an ingredient of multidisciplinary problems. To investigate these problems we will see many different mathematical tools at work: just to mention some, stochastic processes, PDE, normal forms, chaos theory.

  8. Radioactivity of the moon, planets, and meteorites

    Science.gov (United States)

    Surkou, Y. A.; Fedoseyev, G. A.

    1977-01-01

    Analytical data is summarized for the content of natural radioactive elements in meteorites, eruptive terrestrial rocks, and also in lunar samples returned by Apollo missions and the Luna series of automatic stations. The K-U systematics of samples analyzed in the laboratory are combined with data for orbital gamma-ray measurements for Mars (Mars 5) and with the results of direct gamma-ray measurements of the surface of Venus by the Venera 8 lander. Using information about the radioactivity of solar system bodies and evaluations of the content of K, U, and Th in the terrestrial planets, we examine certain aspects of the evolution of material in the protoplanetary gas-dust cloud and then in the planets of the solar system.

  9. International Conference and Advanced School Planet Earth

    CERN Document Server

    Jeltsch, Rolf; Pinto, Alberto; Viana, Marcelo

    2015-01-01

    The focus of this volume is research carried out as part of the program Mathematics of Planet Earth, which provides a platform to showcase the essential role of mathematics in addressing problems of an economic and social nature and creating a context for mathematicians and applied scientists to foster mathematical and interdisciplinary developments that will be necessary to tackle a myriad of issues and meet future global economic and social challenges. Earth is a planet with dynamic processes in its mantle, oceans and atmosphere creating climate, causing natural disasters, and influencing fundamental aspects of life and life-supporting systems. In addition to these natural processes, human activity has developed highly complex systems, including economic and financial systems; the World Wide Web; frameworks for resource management, transportation, energy production and utilization; health care delivery, and social organizations. This development has increased to the point where it impacts the stability and ...

  10. Planet traps and planetary cores: origins of the planet-metallicity correlation

    Energy Technology Data Exchange (ETDEWEB)

    Hasegawa, Yasuhiro [Institute of Astronomy and Astrophysics, Academia Sinica (ASIAA), P.O. Box 23-141, Taipei 10641, Taiwan (China); Pudritz, Ralph E., E-mail: yasu@asiaa.sinica.edu.tw, E-mail: pudritz@physics.mcmaster.ca [Department of Physics and Astronomy, McMaster University, Hamilton, ON L8S 4M1 (Canada)

    2014-10-10

    Massive exoplanets are observed preferentially around high metallicity ([Fe/H]) stars while low-mass exoplanets do not show such an effect. This so-called planet-metallicity correlation generally favors the idea that most observed gas giants at r < 10 AU are formed via a core accretion process. We investigate the origin of this phenomenon using a semi-analytical model, wherein the standard core accretion takes place at planet traps in protostellar disks where rapid type I migrators are halted. We focus on the three major exoplanetary populations—hot Jupiters, exo-Jupiters located at r ≅ 1 AU, and the low-mass planets. We show using a statistical approach that the planet-metallicity correlations are well reproduced in these models. We find that there are specific transition metallicities with values [Fe/H] = –0.2 to –0.4, below which the low-mass population dominates, and above which the Jovian populations take over. The exo-Jupiters significantly exceed the hot Jupiter population at all observed metallicities. The low-mass planets formed via the core accretion are insensitive to metallicity, which may account for a large fraction of the observed super-Earths and hot-Neptunes. Finally, a controlling factor in building massive planets is the critical mass of planetary cores (M {sub c,} {sub crit}) that regulates the onset of rapid gas accretion. Assuming the current data is roughly complete at [Fe/H] > –0.6, our models predict that the most likely value of the 'mean' critical core mass of Jovian planets is (M {sub c,} {sub crit}) ≅ 5 M {sub ⊕} rather than 10 M {sub ⊕}. This implies that grain opacities in accreting envelopes should be reduced in order to lower M {sub c,} {sub crit}.

  11. Planet Earth” wins Emmy

    Science.gov (United States)

    Planet Earth,” the seven-part public television series that explores the strides made in the earth sciences since the International Geophysical Year (IGY) in 1957-1958, won a 1986 Emmy award last month from the Academy of Television Arts and Sciences in the category of Outstanding Informational Series. The series was produced by WQED/Pittsburgh in association with the National Academy of Sciences.

  12. Archaeology of Extrasolar Rocky Minor Planets

    Science.gov (United States)

    Farihi, Jay

    2011-09-01

    Recent and ongoing work has demonstrated that empirical constraints on the frequency and chemistry of rocky planet formation around other stars, and signatures of water therein, can be found via the asteroidal debris orbiting and polluting white dwarf stars. These stellar remnants yield observable information that can be acquired no other way: the frequency, bulk chemical composition, and minimum mass of rocky minor planets around other stars. Asteroids are ancient planetesimals, the building blocks of the terrestrial planets. In the Solar System, we indirectly measure the composition of asteroids by studying meteorites. Analogously, we can obtain a picture of terrestrial planet formation at A- and F-type stars by studying the composition of extant asteroids as they fall onto and chemically pollute their white dwarf remnants. Critically, it is possible to identify significant amounts of water in these asteroidal systems, providing an indication of (current or prior) habitable environments as well as extrasolar testing grounds for models of water delivery to the Earth. I will present the latest and new developments in this area of research. I hope to include some results of an ongoing HST COS effort to study asteroidal debris as a function of post-main sequence age and main-sequence progenitor mass. Other highlights are two stars polluted by the debris of rocky planetary bodies sufficiently large to have been differentiated, and thus at least as large as Vesta or Ceres, the two largest asteroids in the Solar System. Currently, there is at least one compelling case for the accretion of water-rich, asteroidal debris, while the totality of known polluted white dwarfs hints at a significant population of water-rich asteroid analogs orbiting other stars.

  13. Biases in Cometary Catalogues and Planet X

    OpenAIRE

    Horner, J.; Evans, N. W.

    2002-01-01

    Two sets of investigators -- Murray (1999) and Matese, Whitman & Whitmire (1999) -- have recently claimed evidence for an undiscovered Solar System planet from possible great circle alignments in the aphelia directions of the long period comets. However, comet discoveries are bedevilled by selection effects. These include anomalies caused by the excess of observers in the northern as against the southern hemisphere, seasonal and diurnal biases, directional effects which make it harder to disc...

  14. Dust to Dust: Evidence for Planet Formation?

    OpenAIRE

    Schneider, G.; Hines, D. C.; Silverstone, M. D.; Weinberger, A J; Becklin, E. E.; Smith, B. A.

    2001-01-01

    We discuss the properties of several circumstellar debris disk systems imaged with the Hubble Space Telescope's Near Infrared Camera and Multi-Object Spectrometer in a survey of young stars with known far-IR excesses. These dusty disks around young ($\\sim$ 5--8 Myr) unembedded stars exhibit morphological anisotropies and other characteristics which are suggestive of recent or on-going planet formation. We consider evidence for the evolution of populations of collisionally produced disk grains...

  15. Photopolarimetry team outer planets mission definition phase

    Science.gov (United States)

    1972-01-01

    The work is reported of the Photopolarimetry Team in identifying scientific objectives for photometer/polarimeter experiments for outer planet flyby missions. A discussion of the scientific objectives which can be attained with a photometer/polarimeter experiment, and summaries of the special studies which were performed for the Photopolarimetry Team are presented along with a description of the photometer/polarimeter design which was developed for the Meteoroid Detection Team.

  16. The planets of the Solar System

    Science.gov (United States)

    Marov, M. Y.

    1986-01-01

    This book is intended both for the lay person and the would-be scientist. The planets are discussed with a comparision of their basic natural features: mechanical characteristics and parameters of movement, surfaces, inner structure, physical properties of the atmosphere and meteorology. Also general problems of planetary cosmogony, thermal history and climatic evolution are considered briefly. The book is based on Soviet and foreign material, data from spacecraft, Earth optical and radio astronomical measurements and also data obtained from theoretical models.

  17. Evolution of ore deposits on terrestrial planets

    Science.gov (United States)

    Burns, R. G.

    1991-01-01

    Ore deposits on terrestrial planets materialized after core formation, mantle evolution, crustal development, interactions of surface rocks with the hydrosphere and atmosphere, and, where life exists on a planet, the involvement of biological activity. Core formation removed most of the siderophilic and chalcophilic elements, leaving mantles depleted in many of the strategic and noble metals relative to their chondritic abundances. Basaltic magma derived from partial melting of the mantle transported to the surface several metals contained in immiscible silicate and sulfide melts. Magmatic ore deposits were formed during cooling, fractional crystallization and density stratification from the basaltic melts. Such ore deposits found in earth's Archean rocks were probably generated during early histories of all terrestrial planets and may be the only types of igneous ores on Mars. Where plate tectonic activity was prevalent on a terrestrial planet, temporal evolution of ore deposits took place. Repetitive episodes of subduction modified the chemical compositions of the crust and upper mantles, leading to porphyry copper and molybdenum ores in calc-alkaline igneous rocks and granite-hosted tin and tungsten deposits. Such plate tectonic-induced mineralization in relatively young igneous rocks on earth may also have produced hydrothermal ore deposits on Venus in addition to the massive sulfide and cumulate chromite ores associated with Venusian mafic igneous rock. Sedimentary ore deposits resulting from mechanical and chemical weathering in reducing atmospheres in Archean earth included placer deposits (e.g., uraninite, gold, pyrite ores). Chromite, ilmenite, and other dense unreactive minerals could also be present on channel floors and in valley networks on Mars, while banded iron formations might underlie the Martian northern plains regions. As oxygen evolved in earth's atmosphere, so too did oxide ores. By analogy, gossans above sulfide ores probably occur on Mars

  18. SIM's Search for Planets Orbiting White Dwarfs

    Science.gov (United States)

    Subasavage, John P., Jr.

    2009-01-01

    Once launched, The Space Interferometry Mission (SIM) will be the most precise astrometric instrument ever developed. These capabilities are vital to exoplanetary studies, in particular, for low-mass, Earthlike planets. I propose to use SIM to observe a sample ( 25-50) of nearby white dwarfs in hopes of detecting planetary companions with masses in the 10 Earth mass range on average. Because of the nature of white dwarfs' spectral signatures (a few broad, if any, absorption lines), current radial velocity planet hunting techniques are not viable. Astrometry is currently the only technique capable of detecting low mass planets around white dwarfs and SIM would be the best suited astrometric instrument to do so. Planetary detections around white dwarfs would better enable us to probe planetary formation theory as well as planetary evolution theory in conjunction with stellar evolution. Because astrometric signatures are inversely related to distance, the closer the system, the larger the signature (all else being equal). Because most stars will eventually end their lives as white dwarfs, these objects are plentiful and on average, closer to the Sun than more rare objects. Thus, a number of white dwarfs are close enough to the Sun to permit low mass planetary signature detections. Given that white dwarfs are the remnants of main-sequence dwarfs with spectral classes from B to K (thus far), we could better understand planetary formation over a broader range of objects than those currently investigated using radial velocity techniques (F, G, and K stars primarily).

  19. Bayesian Hypothesis Testing for Planet Finding

    Science.gov (United States)

    Braems, I.; Kasdin, N. J.

    2003-12-01

    One of the most important performance metrics of any space planet finding system is integration time. The time needed to make a positive detection of an extrasolar planet determines the number of systems we can observe for the life of the mission and the stability requirements of the spacecraft and optical control systems. Most astronomical detection approaches rely on fairly simple signal-to-noise calculations and a threshold determined by the ability of the human eye to extract the planet image from the background (usually a signal-to-noise ratio of five). In this paper we present an alternative approach to detection using Bayesian hypothesis testing. This optimal approach provides a quantitative measure of the probability of detection under various conditions and integration times (such as known or unknown background levels) and under different prior assumptions. We also show how the technique allows for a much higher probability of detection for shorter integration times than the previous photometric approaches. We gratefully acknowledge the support of the Jet Propulsion Laboratory of the National Aeronautics and Space Administration for this work and Institut National de Recherche en Informatique et Automatique (INRIA) for its support of Ms. Braems.

  20. A Three-Planet Extrasolar System

    Science.gov (United States)

    Lovis, Christophe; Mayor, Michel; Pepe, Francesco; Queloz, Didier; Udry, Stéphane; Santos, Nuno C.; Alibert, Yann; Benz, Willy; Mordasini, Christoph; Bouchy, François; Correia, Alexandre C. M.; Laskar, Jacques; Bertaux, Jean-Loup; Sivan, Jean-Pierre

    2006-06-01

    Using the ultra-precise HARPS spectro-graph on ESO’s 3.6-m telescope at La Silla, a team of astronomers1 has discovered that a nearby star is host to three Neptune-mass planets. The in-nermost planet is most probably rocky, while the outermost is the first known Neptune-mass planet to reside in the habitable zone. This unique system is likely further enriched by an asteroid belt. Z% Lovis et al. 2006, Nature 441, 305. The team is composed of Christophe Lovis, Michel Mayor, Francesco Pepe, Didier Queloz, and Stéphane Udry (Observatoire de l’Université de Genève, Switzerland), Nuno C. Santos (Observatoire de l’Uni-versité de Genève, Switzerland, Centro de Astro-nomia e Astrofisica da Universidade de Lisboa and Centro de Geofisica de Evora, Portugal), Yann Alibert, Willy Benz, Christoph Mordasini (Physikalisches Institut der Universität Bern, Switzerland), François Bouchy (Observatoire de Haute-Provence and IAP, France), Alexandre C. M. Correia (Uni-versidade de Aveiro, Portugal), Jacques Laskar (IMCCE-CNRS, Paris, France), Jean-Loup Bertaux (Service d’Aéronomie du CNRS, France), and Jean-Pierre Sivan (Laboratoire d’Astrophysique de Marseille, France).

  1. The Calan-Hertfordshire extrasolar planet search

    Directory of Open Access Journals (Sweden)

    Pinfield D.J.

    2011-07-01

    Full Text Available The detailed study of the exoplanetary systems HD189733 and HD209458 has given rise to a wealth of exciting information on the physics of exoplanetary atmospheres. To further our understanding of the make-up and processes within these atmospheres we require a larger sample of bright transiting planets. We have began a project to detect more bright transiting planets in the southern hemisphere by utilising precision radial-velocity measurements. We have observed a constrained sample of bright, inactive and metal-rich stars using the HARPS instrument and here we present the current status of this project, along with our first discoveries which include a brown dwarf/extreme-Jovian exoplanet found in the brown dwarf desert region around the star HD191760 and improved orbits for three other exoplanetary systems HD48265, HD143361 and HD154672. Finally, we briefly discuss the future of this project and the current prospects we have for discovering more bright transiting planets.

  2. ON THE LIKELIHOOD OF PLANET FORMATION IN CLOSE BINARIES

    Energy Technology Data Exchange (ETDEWEB)

    Jang-Condell, Hannah, E-mail: hjangcon@uwyo.edu [Department of Physics and Astronomy, University of Wyoming, 1000 East University, Department 3905, Laramie, WY 82071 (United States)

    2015-02-01

    To date, several exoplanets have been discovered orbiting stars with close binary companions (a ≲ 30 AU). The fact that planets can form in these dynamically challenging environments implies that planet formation must be a robust process. The initial protoplanetary disks in these systems from which planets must form should be tidally truncated to radii of a few AU, which indicates that the efficiency of planet formation must be high. Here, we examine the truncation of circumstellar protoplanetary disks in close binary systems, studying how the likelihood of planet formation is affected over a range of disk parameters. If the semimajor axis of the binary is too small or its eccentricity is too high, the disk will have too little mass for planet formation to occur. However, we find that the stars in the binary systems known to have planets should have once hosted circumstellar disks that were capable of supporting planet formation despite their truncation. We present a way to characterize the feasibility of planet formation based on binary orbital parameters such as stellar mass, companion mass, eccentricity, and semimajor axis. Using this measure, we can quantify the robustness of planet formation in close binaries and better understand the overall efficiency of planet formation in general.

  3. Discovering Extrasolar Planets with Microlensing Surveys

    Science.gov (United States)

    Wambsganss, J.

    2016-06-01

    An astronomical survey is commonly understood as a mapping of a large region of the sky, either photometrically (possibly in various filters/wavelength ranges) or spectroscopically. Often, catalogs of objects are produced/provided as the main product or a by-product. However, with the advent of large CCD cameras and dedicated telescopes with wide-field imaging capabilities, it became possible in the early 1990s, to map the same region of the sky over and over again. In principle, such data sets could be combined to get very deep stacked images of the regions of interest. However, I will report on a completely different use of such repeated maps: Exploring the time domain for particular kinds of stellar variability, namely microlens-induced magnifications in search of exoplanets. Such a time-domain microlensing survey was originally proposed by Bohdan Paczynski in 1986 in order to search for dark matter objects in the Galactic halo. Only a few years later three teams started this endeavour. I will report on the history and current state of gravitational microlensing surveys. By now, routinely 100 million stars in the Galactic Bulge are monitored a few times per week by so-called survey teams. All stars with constant apparent brightness and those following known variability patterns are filtered out in order to detect the roughly 2000 microlensing events per year which are produced by stellar lenses. These microlensing events are identified "online" while still in their early phases and then monitored with much higher cadence by so-called follow-up teams. The most interesting of such events are those produced by a star-plus-planet lens. By now of order 30 exoplanets have been discovered by these combined microlensing surveys. Microlensing searches for extrasolar planets are complementary to other exoplanet search techniques. There are two particular advantages: The microlensing method is sensitive down to Earth-mass planets even with ground-based telecopes, and it

  4. Effect of Giant Planet Formation on the Compositional Mixture of the Asteroid Belt

    Science.gov (United States)

    Kretke, Katherine A.; Bottke, William; Kring, David A.; Levison, Harold F.

    2017-06-01

    The asteroid belt is observed to be a mixture of objects with different compositions, with volatile-poor asteroids (mostly S-complex) dominant in the inner asteroid belt while volatile-rich (mostly C-complex) asteroids dominate the outer asteroid belt. While this general compositional stratification was originally thought to be an indicator of the primordial temperature gradient in the protoplanetary disk, the very distinct properties of these populations suggest that they must represent two completely decoupled reservoirs, not a simple gradient (e.g., Warren 2011). It is possible to create this general stratification (as well as the observed mixing) as the implantation of outer Solar System material into the asteroid belt by the early migration of the giant planets (e.g. the Grand Tack, Walsh et al. 2011). However, this presupposes that the inner and outer Solar System materials were still sorted in their primordial locations prior to any migration of the planets. The lack of a fully dynamically self-consistent model of giant planet core formation has prevented the study of how the core formation process itself may result in dynamical mixing in the early Solar System's history. Recently, pebble accretion, the process by which planetesimals can grow to giant planet cores via the accretion of small, rapidly drifting sub-meter-sized bodies known as ``pebbles,'' (Lambrechts & Johansen 2012, Levison, Kretke & Duncan 2015) finally offers such a model. Here we show how the process of giant planet formation will impact the surrounding planetesimal population, possibly resulting in the observed compositional mixture of the asteroid belt, without requiring a dramatic migration of the giant planets. For example, preliminary runs suggest planetesimals from the Jupiter-formation zone can be implanted in the outer main belt via interactions with scattered Jupiter-zone protoplanets. This could potentially provide an alternative non-Grand Tack solution to the origin of many C

  5. Planet Hunters, Undergraduate Research, and Detection of Extrasolar Planet Kepler-818 b

    Science.gov (United States)

    Baker, David; Crannell, Graham; Duncan, James; Hays, Aryn; Hendrix, Landon

    2017-01-01

    Detection of extrasolar planets provides an excellent research opportunity for undergraduate students. In Spring 2012, we searched for transiting extrasolar planets using Kepler spacecraft data in our Research Experience in Physics course at Austin College. Offered during the regular academic year, these Research Experience courses engage students in the scientific process, including proposal writing, paper submission, peer review, and oral presentations. Since 2004, over 190 undergraduate students have conducted authentic scientific research through Research Experience courses at Austin College.Zooniverse’s citizen science Planet Hunters web site offered an efficient method for rapid analysis of Kepler data. Light curves from over 5000 stars were analyzed, of which 2.3% showed planetary candidates already tagged by the Kepler team. Another 1.5% of the light curves suggested eclipsing binary stars, and 1.6% of the light curves had simulated planets for training purposes.One of the stars with possible planetary transits had not yet been listed as a planetary candidate. We reported possible transits for Kepler ID 4282872, which later was promoted to planetary candidate KOI-1325 in 2012 and confirmed to host extrasolar planet Kepler-818 b in 2016 (Morton et al. 2016). Kepler-818 b is a “hot Neptune” with period 10.04 days, flux decrease during transit ~0.4%, planetary radius 4.69 Earth radii, and semi-major axis 0.089 au.

  6. The effect of host star spectral energy distribution and ice-albedo feedback on the climate of extrasolar planets.

    Science.gov (United States)

    Shields, Aomawa L; Meadows, Victoria S; Bitz, Cecilia M; Pierrehumbert, Raymond T; Joshi, Manoj M; Robinson, Tyler D

    2013-08-01

    Planetary climate can be affected by the interaction of the host star spectral energy distribution with the wavelength-dependent reflectivity of ice and snow. In this study, we explored this effect with a one-dimensional (1-D), line-by-line, radiative transfer model to calculate broadband planetary albedos as input to a seasonally varying, 1-D energy balance climate model. A three-dimensional (3-D) general circulation model was also used to explore the atmosphere's response to changes in incoming stellar radiation, or instellation, and surface albedo. Using this hierarchy of models, we simulated planets covered by ocean, land, and water-ice of varying grain size, with incident radiation from stars of different spectral types. Terrestrial planets orbiting stars with higher near-UV radiation exhibited a stronger ice-albedo feedback. We found that ice extent was much greater on a planet orbiting an F-dwarf star than on a planet orbiting a G-dwarf star at an equivalent flux distance, and that ice-covered conditions occurred on an F-dwarf planet with only a 2% reduction in instellation relative to the present instellation on Earth, assuming fixed CO(2) (present atmospheric level on Earth). A similar planet orbiting the Sun at an equivalent flux distance required an 8% reduction in instellation, while a planet orbiting an M-dwarf star required an additional 19% reduction in instellation to become ice-covered, equivalent to 73% of the modern solar constant. The reduction in instellation must be larger for planets orbiting cooler stars due in large part to the stronger absorption of longer-wavelength radiation by icy surfaces on these planets in addition to stronger absorption by water vapor and CO(2) in their atmospheres, which provides increased downwelling longwave radiation. Lowering the IR and visible-band surface ice and snow albedos for an M-dwarf planet increased the planet's climate stability against changes in instellation and slowed the descent into global ice

  7. The Delivery of Water During Terrestrial Planet Formation

    Science.gov (United States)

    O'Brien, David P.; Izidoro, Andre; Jacobson, Seth A.; Raymond, Sean N.; Rubie, David C.

    2018-02-01

    The planetary building blocks that formed in the terrestrial planet region were likely very dry, yet water is comparatively abundant on Earth. Here we review the various mechanisms proposed for the origin of water on the terrestrial planets. Various in-situ mechanisms have been suggested, which allow for the incorporation of water into the local planetesimals in the terrestrial planet region or into the planets themselves from local sources, although all of those mechanisms have difficulties. Comets have also been proposed as a source, although there may be problems fitting isotopic constraints, and the delivery efficiency is very low, such that it may be difficult to deliver even a single Earth ocean of water this way. The most promising route for water delivery is the accretion of material from beyond the snow line, similar to carbonaceous chondrites, that is scattered into the terrestrial planet region as the planets are growing. Two main scenarios are discussed in detail. First is the classical scenario in which the giant planets begin roughly in their final locations and the disk of planetesimals and embryos in the terrestrial planet region extends all the way into the outer asteroid belt region. Second is the Grand Tack scenario, where early inward and outward migration of the giant planets implants material from beyond the snow line into the asteroid belt and terrestrial planet region, where it can be accreted by the growing planets. Sufficient water is delivered to the terrestrial planets in both scenarios. While the Grand Tack scenario provides a better fit to most constraints, namely the small mass of Mars, planets may form too fast in the nominal case discussed here. This discrepancy may be reduced as a wider range of initial conditions is explored. Finally, we discuss several more recent models that may have important implications for water delivery to the terrestrial planets.

  8. The Pan-Pacific Planet Search. VII. The Most Eccentric Planet Orbiting a Giant Star

    Science.gov (United States)

    Wittenmyer, Robert A.; Jones, M. I.; Horner, Jonathan; Kane, Stephen R.; Marshall, J. P.; Mustill, A. J.; Jenkins, J. S.; Pena Rojas, P. A.; Zhao, Jinglin; Villaver, Eva; Butler, R. P.; Clark, Jake

    2017-12-01

    Radial velocity observations from three instruments reveal the presence of a 4 M Jup planet candidate orbiting the K giant HD 76920. HD 76920b has an orbital eccentricity of 0.856 ± 0.009, making it the most eccentric planet known to orbit an evolved star. There is no indication that HD 76920 has an unseen binary companion, suggesting a scattering event rather than Kozai oscillations as a probable culprit for the observed eccentricity. The candidate planet currently approaches to about four stellar radii from its host star, and is predicted to be engulfed on a ∼100 Myr timescale due to the combined effects of stellar evolution and tidal interactions.

  9. The impact of red noise in radial velocity planet searches: only three planets orbiting GJ 581?

    Science.gov (United States)

    Baluev, Roman V.

    2013-03-01

    We perform a detailed analysis of the latest HARPS and Keck radial velocity data for the planet-hosting red dwarf GJ 581, which attracted a lot of attention in recent time. We show that these data contain important correlated noise component (`red noise') with the correlation time-scale of the order of 10 d. This red noise imposes a lot of misleading effects while we work in the traditional white-noise model. To eliminate these misleading effects, we propose a maximum-likelihood algorithm equipped by an extended model of the noise structure. We treat the red noise as a Gaussian random process with an exponentially decaying correlation function. Using this method we prove that (i) planets b and c do exist in this system, since they can be independently detected in the HARPS and Keck data, and regardless of the assumed noise models; (ii) planet e can also be confirmed independently by both the data sets, although to reveal it in the Keck data it is mandatory to take the red noise into account; (iii) the recently announced putative planets f and g are likely just illusions of the red noise; (iv) the reality of the planet candidate GJ 581 d is questionable, because it cannot be detected from the Keck data, and its statistical significance in the HARPS data (as well as in the combined data set) drops to a marginal level of ˜2σ, when the red noise is taken into account. Therefore, the current data for GJ 581 really support the existence of no more than four (or maybe even only three) orbiting exoplanets. The planet candidate GJ 581 d requests serious observational verification.

  10. The Longevity of Water Ice on Ganymedes and Europas around Migrated Giant Planets

    Science.gov (United States)

    Lehmer, Owen R.; Catling, David C.; Zahnle, Kevin J.

    2017-04-01

    The gas giant planets in the Solar System have a retinue of icy moons, and we expect giant exoplanets to have similar satellite systems. If a Jupiter-like planet were to migrate toward its parent star the icy moons orbiting it would evaporate, creating atmospheres and possible habitable surface oceans. Here, we examine how long the surface ice and possible oceans would last before being hydrodynamically lost to space. The hydrodynamic loss rate from the moons is determined, in large part, by the stellar flux available for absorption, which increases as the giant planet and icy moons migrate closer to the star. At some planet-star distance the stellar flux incident on the icy moons becomes so great that they enter a runaway greenhouse state. This runaway greenhouse state rapidly transfers all available surface water to the atmosphere as vapor, where it is easily lost from the small moons. However, for icy moons of Ganymede’s size around a Sun-like star we found that surface water (either ice or liquid) can persist indefinitely outside the runaway greenhouse orbital distance. In contrast, the surface water on smaller moons of Europa’s size will only persist on timescales greater than 1 Gyr at distances ranging 1.49-0.74 au around a Sun-like star for Bond albedos of 0.2 and 0.8, where the lower albedo becomes relevant if ice melts. Consequently, small moons can lose their icy shells, which would create a torus of H atoms around their host planet that might be detectable in future observations.

  11. Wandering stars about planets and exo-planets : an introductory notebook

    CERN Document Server

    Cole, George H A

    2006-01-01

    The space vehicle spectaculars of recent years have been revealing the full scope and beauty of our own solar system but have also shown that a growing number of other stars too have planetary bodies orbiting around them. The study of these systems is just beginning. It seems that our galaxy contains untold numbers of planets, and presumably other galaxies will be similar to our own. Our solar system contains life, on Earth: do others as well? Such questions excite modern planetary scientists and astro-biologists. This situation is a far cry from ancient times when the five planets that can be

  12. Giant Planet Candidates, Brown Dwarfs, and Binaries from the SDSS-III MARVELS Planet Survey.

    Science.gov (United States)

    Thomas, Neil; Ge, Jian; Li, Rui; de Lee, Nathan M.; Heslar, Michael; Ma, Bo; SDSS-Iii Marvels Team

    2015-01-01

    We report the discoveries of giant planet candidates, brown dwarfs, and binaries from the SDSS-III MARVELS survey. The finalized 1D pipeline has provided 18 giant planet candidates, 16 brown dwarfs, and over 500 binaries. An additional 96 targets having RV variability indicative of a giant planet companion are also reported for future investigation. These candidates are found using the advanced MARVELS 1D data pipeline developed at UF from scratch over the past three years. This pipeline carefully corrects most of the instrument effects (such as trace, slant, distortion, drifts and dispersion) and observation condition effects (such as illumination profile, fiber degradation, and tracking variations). The result is long-term RV precisions that approach the photon limits in many cases for the ~89,000 individual stellar observations. A 2D version of the pipeline that uses interferometric information is nearing completion and is demonstrating a reduction of errors to half the current levels. The 2D processing will be used to increase the robustness of the detections presented here and to find new candidates in RV regions not confidently detectable with the 1D pipeline. The MARVELS survey has produced the largest homogeneous RV measurements of 3300 V=7.6-12 FGK stars with a well defined cadence of 27 RV measurements over 2 years. The MARVELS RV data and other follow-up data (photometry, high contrast imaging, high resolution spectroscopy and RV measurements) will explore the diversity of giant planet companion formation and evolution around stars with a broad range in metallicity (Fe/H -1.5-0.5), mass ( 0.6-2.5M(sun)), and environment (thin disk and thick disk), and will help to address the key scientific questions identified for the MARVELS survey including, but not limited to: Do metal poor stars obey the same trends for planet occurrence as metal rich stars? What is the distribution of giant planets around intermediate-mass stars and binaries? Is the 'planet desert

  13. The effect of planets beyond the ice line on the accretion of volatiles by habitable-zone rocky planets

    Energy Technology Data Exchange (ETDEWEB)

    Quintana, Elisa V. [SETI Institute, 189 Bernardo Avenue, Suite 100, Mountain View, CA 94043 (United States); Lissauer, Jack J., E-mail: elisa.quintana@nasa.gov [Space Science and Astrobiology Division 245-3, NASA Ames Research Center, Moffett Field, CA 94035 (United States)

    2014-05-01

    Models of planet formation have shown that giant planets have a large impact on the number, masses, and orbits of terrestrial planets that form. In addition, they play an important role in delivering volatiles from material that formed exterior to the snow line (the region in the disk beyond which water ice can condense) to the inner region of the disk where terrestrial planets can maintain liquid water on their surfaces. We present simulations of the late stages of terrestrial planet formation from a disk of protoplanets around a solar-type star and we include a massive planet (from 1 M {sub ⊕} to 1 M {sub J}) in Jupiter's orbit at ∼5.2 AU in all but one set of simulations. Two initial disk models are examined with the same mass distribution and total initial water content, but with different distributions of water content. We compare the accretion rates and final water mass fraction of the planets that form. Remarkably, all of the planets that formed in our simulations without giant planets were water-rich, showing that giant planet companions are not required to deliver volatiles to terrestrial planets in the habitable zone. In contrast, an outer planet at least several times the mass of Earth may be needed to clear distant regions of debris truncating the epoch of frequent large impacts. Observations of exoplanets from radial velocity surveys suggest that outer Jupiter-like planets may be scarce, therefore, the results presented here suggest that there may be more habitable planets residing in our galaxy than previously thought.

  14. Combining high-dispersion spectroscopy with high contrast imaging: Probing rocky planets around our nearest neighbors

    Science.gov (United States)

    Snellen, I.; de Kok, R.; Birkby, J. L.; Brandl, B.; Brogi, M.; Keller, C.; Kenworthy, M.; Schwarz, H.; Stuik, R.

    2015-04-01

    baseline parameters of the E-ELT and METIS instrument, with the latter combining extreme adaptive optics with an R = 100 000 IFS. We include realistic models of the adaptive optics performance and atmospheric transmission and emission. For the optical simulation we also assume R = 100 000 IFS with adaptive optics capabilities at the E-ELT. Results: One night of HDS+HCI observations with the E-ELT at 4.8 μm (Δλ = 0.07 μm) can detect a planet orbiting α Cen A with a radius of R = 1.5 Rearth and a twin-Earth thermal spectrum of Teq = 300 K at a signal-to-noise (S/N) of 5. In the optical, with a Strehl ratio performance of 0.3, reflected light from an Earth-size planet in the habitable zone of Proxima Centauri can be detected at a S/N of 10 in the same time frame. Recently, first HDS+HCI observations have shown the potential of this technique by determining the spin-rotation of the young massive exoplanet β Pictoris b. Conclusions: The exploration of the planetary systems of our neighbor stars is of great scientific and philosophical value. The HDS+HCI technique has the potential to detect and characterize temperate rocky planets in their habitable zones. Exoplanet scientists should not shy away from claiming a significant fraction of the future ELTs to make such observations possible.

  15. Stable habitable zones of single Jovian planet systems

    Science.gov (United States)

    Agnew, Matthew T.; Maddison, Sarah T.; Thilliez, Elodie; Horner, Jonathan

    2017-11-01

    With continued improvement in telescope sensitivity and observational techniques, the search for rocky planets in stellar habitable zones is entering an exciting era. With so many exoplanetary systems available for follow-up observations to find potentially habitable planets, one needs to prioritize the ever-growing list of candidates. We aim to determine which of the known planetary systems are dynamically capable of hosting rocky planets in their habitable zones, with the goal of helping to focus future planet search programmes. We perform an extensive suite of numerical simulations to identify regions in the habitable zones of single Jovian planet systems where Earth-mass planets could maintain stable orbits, specifically focusing on the systems in the Catalog of Earth-like Exoplanet Survey Targets (CELESTA). We find that small, Earth-mass planets can maintain stable orbits in cases where the habitable zone is largely, or partially, unperturbed by a nearby Jovian, and that mutual gravitational interactions and resonant mechanisms are capable of producing stable orbits even in habitable zones that are significantly or completely disrupted by a Jovian. Our results yield a list of 13 single Jovian planet systems in CELESTA that are not only capable of supporting an Earth-mass planet on stable orbits in their habitable zone, but for which we are also able to constrain the orbits of the Earth-mass planet such that the induced radial velocity signals would be detectable with next generation instruments.

  16. The Freezing Conditions of Planets: Effect of Obliquity

    Science.gov (United States)

    Abe, Y.; Abe-Ouchi, A.

    2002-12-01

    Condition for the occurrence of the completely frozen state (a "snow-ball" state) might be a critical measure related to the habitability of the planet. It is investigated with a particular reference to the obliquity for both a land planet case and an aqua planet case. Obliquity change may cause freezing and unfreezing of planet if the freezing condition depends on the obliquity. Effect of obliquity on the freezing is also an important issue for the investigation of the paleo-Mars. Here we investigated the freezing condition by a general circulation model, CCSR/NIES AGCM 5.4g. We applied the Earth condition, but assumed no topography and applied a bucket model with the saturation depth of 10 cm for ground water calculation for the land planet case and 50m slab ocean for the aqua planet case. The results are summarized as follows: 1. A land planet shows stronger resistance to the complete freezing than an aqua planet. 2. A land planet in an oblique regime falls in the completely frozen state at a smaller solar constant than an upright regime. 3. On a land planet in an oblique regime, low latitude area is more susceptible to freezing than the mid latitude area. Implication for the paleo-Mars will be discussed in the presentation.

  17. PREDICTING A THIRD PLANET IN THE KEPLER-47 CIRCUMBINARY SYSTEM

    Energy Technology Data Exchange (ETDEWEB)

    Hinse, Tobias C. [Korea Astronomy and Space Science Institute (Korea, Republic of); Haghighipour, Nader [Institute for Astronomy, University of Hawaii-Manoa, Honolulu, HI (United States); Kostov, Veselin B. [Johns Hopkins University, Baltimore, MD (United States); Goździewski, Krzysztof, E-mail: tchinse@gmail.com [Toruń Centre for Astronomy of the Nicolai Copernicus University, Grudziadzka 5 (Poland)

    2015-01-20

    We have studied the possibility that a third circumbinary planet in the Kepler-47 planetary system is the source of the single unexplained transiting event reported during the discovery of these planets. We applied the MEGNO technique to identify regions in the phase space where a third planet can maintain quasi-periodic orbits, and assessed the long-term stability of the three-planet system by integrating the entire five bodies (binary + planets) for 10 Myr. We identified several stable regions between the two known planets as well as a region beyond the orbit of Kepler-47c where the orbit of the third planet could be stable. To constrain the orbit of this planet, we used the measured duration of the unexplained transit event (∼4.15 hr) and compared that with the transit duration of the third planet in an ensemble of stable orbits. To remove the degeneracy among the orbits with similar transit durations, we considered the planet to be in a circular orbit and calculated its period analytically. The latter places an upper limit of 424 days on the orbital period of the third planet. Our analysis suggests that if the unexplained transit event detected during the discovery of the Kepler-47 circumbinary system is due to a planetary object, this planet will be in a low eccentricity orbit with a semi-major axis smaller than 1.24 AU. Further constraining of the mass and orbital elements of this planet requires a re-analysis of the entire currently available data, including those obtained post-announcement of the discovery of this system. We present details of our methodology and discuss the implication of the results.

  18. Planet Formation Instrument for the Thirty Meter Telescope

    Energy Technology Data Exchange (ETDEWEB)

    Macintosh, B; Troy, M; Graham, J; Doyon, R

    2006-02-22

    In the closing years of the 20th Century humankind began its exploration of the planetary systems in the solar neighborhood. Precision radial velocity measurements have now yielded the discovery of over 160 planets. Direct imaging of these planets, as opposed to detection of the effects of orbital motion on their parent star, is now feasible, and the first young planet in a wide orbit may have been detected using adaptive optics systems. Gemini and the VLT are building the first generation of high contrast adaptive optics systems, which deliver planet-imaging performance within few Airy rings of the host star. These systems will make the first surveys of the outer regions of solar systems by detecting the self-luminous radiation of young planets. These instruments will establish whether Jovian planets form predominantly through 'top-down' (global gravitational instability) or 'bottom-up' (core accretion) processes. The 8-m 'extreme' AO systems cannot see close enough to the host stars to image Doppler planets, and they cannot reach the relatively distant, young clusters and associations where planets are forming. The Planet Formation Instrument will use the nearly four-fold improved angular resolution of TMT to peer into the inner solar systems of Doppler-planet bearing stars to yield a unified sample of planets with known Keplerian orbital elements and atmospheric properties. In star formation regions, where T Tauri stars (young solar type stars) are found in abundance, PFI can see into the snow line, where the icy cores of planets like Jupiter must have formed. Thus, TMT will be the first facility to witness the formation of new planets.

  19. The stellar occultation by the dwarf planet Haumea

    Science.gov (United States)

    Santos-Sanz, Pablo; Ortiz, Jose Luis; Sicardy, Bruno; Rossi, Gustavo; Berard, Diane; Morales, Nicolas; Duffard, Rene; Braga-Ribas, Felipe; Hopp, Ulrich; Ries, Christoph; Nascimbeni, Valerio; Marzari, Francesco; Granata, Valentina; Pál, András; Kiss, Csaba; Pribulla, Theodor; Milan Komzík, Richard; Hornoch, Kamil; Pravec, Petr; Bacci, Paolo; Maestripieri, Martina; Nerli, Luca; Mazzei, Leonardo; Bachini, Mauro; Martinelli, Fabio; Succi, Giacomo; Ciabattari, Fabrizio; Mikuz, Herman; Carbognani, Albino; Gaehrken, Bernd; Mottola, Stefano; Hellmich, Stephan; Rommel, Flavia; Fernández-Valenzuela, Estela; Campo Bagatin, Adriano; Haumea occultation international Collaboration: https://cloud.iaa.csic.es/public.php?service=files&t=d9276f8ab1a316cef13bee28bef75add

    2017-10-01

    The dwarf planet Haumea is a very peculiar Trans-Neptunian Object (TNO) with unique and exotic characteristics. It is currently classified as one of the five dwarf planets of the solar system, and it is the only one for which size, shape, albedo, density and other basic properties were not accurately known. To solve that we predicted an occultation of the star GaiaDR1 1233009038221203584 by Haumea and organized observations within the expected shadow path. Medium/large telescopes were needed to record the occultation with enough signal to noise ratio because the occulted star is of similar brightness as Haumea (R~17.7 mag). We will report results derived from this successful stellar occultation by Haumea on 2017 January 21st. The occultation was positive from 12 telescopes at 10 observing stations in Europe: the Asiago Observatory 1.8m telescope (Italy), the Mount Agliale Observatory 0.5m telescope (Italy), the Lajatico Astronomical Centre 0.5m telescope (Italy), the S.Marcello Pistoiese Observatory 0.6m telescope (Italy), the Crni Vrh Observatory 0.6m telescope (Slovenia), the Ondrejov Observatory 0.65m telescope (Czech Republic), the Bavarian Public Observatory 0.81m telescope (Germany), the Konkoly Observatory 1m and 0.6m telescopes (Hungary), the Skalnate Pleso Observatory 1.3m telescope (Slovakia), and the Wendelstein Observatory 2m and 0.4m telescopes (Germany). This is the occultation by a TNO with the largest number of chords ever recorded.Part of this work has received funding from the European Union’s Horizon 2020 Research and Innovation Programme under Grant Agreement No. 687378.

  20. Characterizing Debris Disks in the Late Stages of Planet Formation

    Science.gov (United States)

    White, Jacob

    2018-01-01

    The planet formation process shapes the morphology and grain size distribution of circumstellar disks, encoding the formation history of a given system. Remnants of planet formation, such as comets and asteroids, collisionally evolve and can replenish the dust and small solids that would otherwise be cleared on short timescales. These grains are observed through reprocessed starlight at submm to cm wavelengths.The spectrum of the mm/cm emission reveals details of the grain population. However, one confounding parameter in studying these grains around stars is the stars themselves. The emission from stars in the mm/cm is nontrivial and generally not well-constrained. I will present examples of debris systems (HD 141569 and Fomalhaut) studied by ALMA and the VLA, in which unconstrained stellar emission may be contributing to the observed flux densities. Such contamination in turn biases the inferred emission from the disk and the corresponding dust properties. In some cases, the behavior of the observed A/B stars can exhibit an emission profile that has similarities to that of the Sun's mm/cm emission, although the same processes are not thought to necessarily occur in the atmospheres of massive stars.To address the uncertainty in stellar emission at mm/cm wavelengths, we present ongoing radio observations (JCMT, SMA, VLA) of Sirius A, which is a bright, nearby star with no known debris. We seek to use this system to set an observationally determined standard for stellar atmosphere modeling and debris disk studies around A stars, as well as to take the first step toward characterizing potential intrinsic uncertainty in stellar emission at these wavelengths. This talk will highlight the effort to characterize stellar atmospheres through a project known as MESAS (Measuring the Emission of Stellar Atmospheres at Submillimeter/millimeter wavelengths) which is imperative to the success of current and future debris disk studies.

  1. Characterizing Debris Disks and the Late Stages of Planet Formation

    Science.gov (United States)

    White, Jacob

    2017-10-01

    The planet formation process shapes the morphology and grain size distribution of circumstellar disks, encoding the formation history of a given system. Remnants of planet formation, such as comets and asteroids, collisionally evolve and can replenish the dust and small solids that would otherwise be cleared on short timescales. These grains are observed through reprocessed starlight at submm to cm wavelengths.The spectrum of the mm/cm emission reveals details of the grain population. However, one confounding parameter in studying these grains around stars is the stars themselves. The emission from stars in the mm/cm is nontrivial and generally not well-constrained. I will present examples of debris systems (HD 141569 and Fomalhaut) studied by ALMA and the VLA, in which unconstrained stellar emission may be contributing to the observed flux densities. Such contamination in turn biases the inferred emission from the disk and the corresponding dust properties. In some cases, the behavior of the observed A/B stars can exhibit an emission profile that has similarities to that of the Sun's mm/cm emission, although the same processes are not thought to necessarily occur in the atmospheres of massive stars.To address the uncertainty in stellar emission at mm/cm wavelengths, we present ongoing radio observations (JCMT, SMA, VLA) of Sirius A, which is a bright, nearby star with no known debris. We seek to use this system to set an observationally determined standard for stellar atmosphere modeling and debris disk studies around A stars, as well as to take the first step toward characterizing potential intrinsic uncertainty in stellar emission at these wavelengths. This talk will highlight the effort to characterize stellar atmospheres through a project known as MESAS (Measuring the Emission of Stellar Atmospheres at Submillimeter/millimeter wavelengths) which is imperative to the success of current and future debris disk studies.

  2. Atmospheric tides in Earth-like planets

    Science.gov (United States)

    Auclair-Desrotour, P.; Laskar, J.; Mathis, S.

    2017-07-01

    Context. Atmospheric tides can strongly affect the rotational dynamics of planets. In the family of Earth-like planets, which includes Venus, this physical mechanism coupled with solid tides makes the angular velocity evolve over long timescales and determines the equilibrium configurations of their spin. Aims: Unlike the solid core, the atmosphere of a planet is subject to both tidal gravitational potential and insolation flux coming from the star. The complex response of the gas is intrinsically linked to its physical properties. This dependence has to be characterized and quantified for application to the wide variety of extrasolar planetary systems. Methods: We develop a theoretical global model where radiative losses, which are predominant in slowly rotating atmospheres, are taken into account. We analytically compute the perturbation of pressure, density, temperature, and velocity field caused by a thermogravitational tidal perturbation. From these quantities, we deduce the expressions of atmospheric Love numbers and tidal torque exerted on the fluid shell by the star. The equations are written for the general case of a thick envelope and the simplified one of a thin isothermal atmosphere. Results: The dynamics of atmospheric tides depends on the frequency regime of the tidal perturbation: the thermal regime near synchronization and the dynamical regime characterizing fast-rotating planets. Gravitational and thermal perturbations imply different responses of the fluid, I.e. gravitational tides and thermal tides, which are clearly identified. The dependence of the torque on the tidal frequency is quantified using the analytic expressions of the model for Earth-like and Venus-like exoplanets and is in good agreement with the results given by global climate models (GCM) simulations.Introducing dissipative processes such as radiation regularizes the tidal response of the atmosphere, otherwise it is singular at synchronization. Conclusions: We demonstrate the

  3. The Spherical Bolometric Albedo of Planet Mercury

    OpenAIRE

    Mallama, Anthony

    2017-01-01

    Published reflectance data covering several different wavelength intervals has been combined and analyzed in order to determine the spherical bolometric albedo of Mercury. The resulting value of 0.088 +/- 0.003 spans wavelengths from 0 to 4 {\\mu}m which includes over 99% of the solar flux. This bolometric result is greater than the value determined between 0.43 and 1.01 {\\mu}m by Domingue et al. (2011, Planet. Space Sci., 59, 1853-1872). The difference is due to higher reflectivity at wavelen...

  4. Mars: A water-rich planet

    Science.gov (United States)

    Carr, Michael H.

    1987-01-01

    Good geomorphic evidence is presented for a planet that was once water rich, and that a lower limit on the amount of water available for a given Martian watershed may be estimated by assuming that the volume of material eroded was equal to the volume of water available. This estimate, coupled with high latitude water estimates of 50 to 100 m gives a global inventory of about 500 m total water in the subsurface. It was emphasized that this is a lower limit as considerable water may be bound in weathered debris and in primary minerals.

  5. Extrasolar planet observational studies: the Italian contribution.

    Science.gov (United States)

    Gratton, R.; Desidera, S.; Claudi, R.

    We review the Italian contribution to observationals studies of extrasolar planets. Various techniques are used, including high precision radial velocities, transits, time delays, and direct imaging. Italian groups participate to some of the most interesting projects of the next decade, including imaging, photometry and astrometry. We will focus our attention on a few of these projects, including results obtained with SARG at TNG, those expected from OmegaTrans at VST, SPHERE at VLT and EPICS at E-ELT, with the PLATO satellite, and with GAIA.

  6. Planetesimal-driven planet migration in the presence of a gas disk

    Science.gov (United States)

    Capobianco, Christopher C.; Duncan, Martin; Levison, Harold F.

    2011-01-01

    We report here on an extension of a previous study by Kirsh et al. (Kirsh, D.R., Duncan, M., Brasser, R., Levison, H.F. [2009]. Icarus 199, 197-209) of planetesimal-driven migration using our N-body code SyMBA (Duncan, M.J., Levison, H.F., Lee, M.H. [1998]. Astron. J. 116, 2067-2077). The previous work focused on the case of a single planet of mass Mem, immersed in a planetesimal disk with a power-law surface density distribution and Rayleigh distributed eccentricities and inclinations. Typically 10 4-10 5 equal-mass planetesimals were used, where the gravitational force (and the back-reaction) on each planetesimal by the Sun and planet were included, while planetesimal-planetesimal interactions were neglected. The runs reported on here incorporate the dynamical effects of a gas disk, where the Adachi et al. (Adachi, I., Hayashi, C., Nakazawa, K. [1976]. Prog. Theor. Phys. 56, 1756-1771) prescription of aerodynamic gas drag is implemented for all bodies. In some cases the Papaloizou and Larwood (Papaloizou, J.C.B., Larwood, J.D. [2000]. Mon. Not. R. Astron. Soc. 315, 823-833) prescription of Type-I migration for the planet are implemented, as well as a mass distribution. In the gas-free cases, rapid planet migration was observed - at a rate independent of the planet's mass - provided the planet's mass was not large compared to the mass in planetesimals capable of entering its Hill sphere. In such cases, both inward and outward migrations can be self-sustaining, but there is a strong propensity for inward migration. When a gas disk is present, aerodynamic drag can substantially modify the dynamics of scattered planetesimals. For sufficiently large or small mono-dispersed planetesimals, the planet typically migrates inward. However, for a range of plausible planetesimal sizes (i.e. 0.5-5.0 km at 5.0 AU in a minimum mass Hayashi disk) outward migration is usually triggered, often accompanied by substantial planetary mass accretion. The origins of this behaviour are

  7. Coordinated X-Ray and Optical Observations of Star-Planet Interaction in HD 17156

    Science.gov (United States)

    Maggio, A.; Pillitteri, I.; Scandariato, G.; Lanza, A. F.; Sciortino, S.; Borsa, F.; Bonomo, A. S.; Claudi, R.; Covino, E.; Desidera, S.; Gratton, R.; Micela, G.; Pagano, I.; Piotto, G.; Sozzetti, A.; Cosentino, R.; Maldonado, J.

    2015-09-01

    The large number of close-in Jupiter-size exoplanets prompts the question whether star-planet interaction (SPI) effects can be detected. We focused our attention on the system HD 17156, having a Jupiter-mass planet in a very eccentric orbit. Here we present results of the XMM-Newton observations and of a five month coordinated optical campaign with the HARPS-N spectrograph.10 We observed HD 17156 with XMM-Newton when the planet was approaching the apoastron and then at the following periastron passage, quasi-simultaneously with HARPS-N. We obtained a clear (≈ 5.5σ ) X-ray detection only at the periastron visit, accompanied by a significant increase of the {R}{HK}\\prime chromospheric index. We discuss two possible scenarios for the activity enhancement: magnetic reconnection and flaring or accretion onto the star of material tidally stripped from the planet. In any case, this is possibly the first evidence of a magnetic SPI effect caught in action.

  8. UV SURFACE ENVIRONMENT OF EARTH-LIKE PLANETS ORBITING FGKM STARS THROUGH GEOLOGICAL EVOLUTION

    Energy Technology Data Exchange (ETDEWEB)

    Rugheimer, S.; Sasselov, D. [Harvard Smithsonian Center for Astrophysics, 60 Garden st., 02138 MA Cambridge (United States); Segura, A. [Instituto de Ciencias Nucleares, Universidad Nacional Autónoma de México, México (Mexico); Kaltenegger, L., E-mail: srugheimer@cfa.harvard.edu [Carl Sagan Institute, Cornell University, Ithaca, NY 14853 (United States)

    2015-06-10

    The UV environment of a host star affects the photochemistry in the atmosphere, and ultimately the surface UV environment for terrestrial planets and therefore the conditions for the origin and evolution of life. We model the surface UV radiation environment for Earth-sized planets orbiting FGKM stars in the circumstellar Habitable Zone for Earth through its geological evolution. We explore four different types of atmospheres corresponding to an early-Earth atmosphere at 3.9 Gyr ago and three atmospheres covering the rise of oxygen to present-day levels at 2.0 Gyr ago, 0.8 Gyr ago, and modern Earth. In addition to calculating the UV flux on the surface of the planet, we model the biologically effective irradiance, using DNA damage as a proxy for biological damage. We find that a pre-biotic Earth (3.9 Gyr ago) orbiting an F0V star receives 6 times the biologically effective radiation as around the early Sun and 3520 times the modern Earth–Sun levels. A pre-biotic Earth orbiting GJ 581 (M3.5 V) receives 300 times less biologically effective radiation, about 2 times modern Earth–Sun levels. The UV fluxes calculated here provide a grid of model UV environments during the evolution of an Earth-like planet orbiting a range of stars. These models can be used as inputs into photo-biological experiments and for pre-biotic chemistry and early life evolution experiments.

  9. Forecasting the detectability of known radial velocity planets with the upcoming CHEOPS mission

    Science.gov (United States)

    Yi, Joo Sung; Chen, Jingjing; Kipping, David

    2018-01-01

    The Characterizing Exoplanets Satellite (CHEOPS) mission is planned for launch next year with a major objective being to search for transits of known RV planets, particularly those orbiting bright stars. Since the radial velocity method is only sensitive to planetary mass, the radii, transit depths and transit signal-to-noise values of each RV planet are, a-priori, unknown. Using an empirically calibrated probabilistic mass-radius relation, forecaster (Chen & Kipping 2017a), we address this by predicting a catalog of homogeneous credible intervals for these three keys terms for 468 planets discovered via radial velocities. Of these, we find that the vast majority should be detectable with CHEOPS, including terrestrial bodies, if they have the correct geometric alignment. In particular, we predict that 22 mini-Neptunes and 82 Neptune-sized planets would be suitable for detection and that more than 80% of these will have apparent magnitude of V < 10, making them highly suitable for follow-up characterization work. Our work aims to assist the CHEOPS team in scheduling efforts and highlights the great value of quantifiable, statistically robust estimates for upcoming exoplanetary missions.

  10. A giant planet beyond the snow line in microlensing event OGLE-2011-BLG-0251

    DEFF Research Database (Denmark)

    Kains, N.; Street, R.A.; Choi, J.-Y.

    2013-01-01

    curve, we find that the lens is composed of two masses with a mass ratio q = 1.9 × 10-3. Thanks to our detection of higher-order effects on the light curve due to the Earth's orbital motion and the finite size of source, we are able to measure the mass and distance to the lens unambiguously. Results. We...... find that the lens is made up of a planet of mass 0.53 ± 0.21 M J orbiting an M dwarf host star with a mass of 0.26 ± 0.11 M⊙. The planetary system is located at a distance of 2.57 ± 0.61 kpc towards the Galactic centre. The projected separation of the planet from its host star is d = 1.408 ± 0.......019, in units of the Einstein radius, which corresponds to 2.72 ± 0.75 AU in physical units. We also identified a competitive model with similar planet and host star masses, but with a smaller orbital radius of 1.50 ± 0.50 AU. The planet is therefore located beyond the snow line of its host star, which we...

  11. Correlations between Compositions and Orbits Established by the Giant Impact Era of Planet Formation

    Science.gov (United States)

    Dawson, Rebekah I.; Lee, Eve J.; Chiang, Eugene

    2016-05-01

    The giant impact phase of terrestrial planet formation establishes connections between super-Earths’ orbital properties (semimajor axis spacings, eccentricities, mutual inclinations) and interior compositions (the presence or absence of gaseous envelopes). Using N-body simulations and analytic arguments, we show that spacings derive not only from eccentricities, but also from inclinations. Flatter systems attain tighter spacings, a consequence of an eccentricity equilibrium between gravitational scatterings, which increase eccentricities, and mergers, which damp them. Dynamical friction by residual disk gas plays a critical role in regulating mergers and in damping inclinations and eccentricities. Systems with moderate gas damping and high solid surface density spawn gas-enveloped super-Earths with tight spacings, small eccentricities, and small inclinations. Systems in which super-Earths coagulate without as much ambient gas, in disks with low solid surface density, produce rocky planets with wider spacings, larger eccentricities, and larger mutual inclinations. A combination of both populations can reproduce the observed distributions of spacings, period ratios, transiting planet multiplicities, and transit duration ratios exhibited by Kepler super-Earths. The two populations, both formed in situ, also help to explain observed trends of eccentricity versus planet size, and bulk density versus method of mass measurement (radial velocities versus transit timing variations). Simplifications made in this study—including the limited time span of the simulations, and the approximate treatments of gas dynamical friction and gas depletion history—should be improved on in future work to enable a detailed quantitative comparison to the observations.

  12. Disk-Planet Torques from Radiation-Hydrodynamics Calculations with Spatially-Resolved Planetary Envelopes Undergoing Solids' Accretion

    Science.gov (United States)

    D'Angelo, G.

    2016-12-01

    D'Angelo & Bodenheimer (2013, ApJ, 778, 77) performed global 3D radiation-hydrodynamics disk-planet simulations aimed at studying envelope formation around planetary cores, during the phase of sustained planetesimal accretion. The calculations modeled cores of 5, 10, and 15 Earth masses orbiting a sun-like star in a protoplanetary disk extending from ap/2 to 2ap in radius, ap=5 or 10 AU being the core's orbital radius. The gas equation of state - for a solar mixture of H2, H, He - accounted for translational, rotational, and vibrational states, for molecular dissociation and atomic ionization, and for radiation energy. Dust opacity calculations applied the Mie theory to multiple grain species whose size distributions ranged from 5e-6 to 1 mm. Mesh refinement via grid nesting allowed the planets' envelopes to be resolved at the core-radius length scale. Passive tracers were used to determine the volume of gas bound to a core, defining the envelope, and resulting in planet radii comparable to the Bondi radius. The energy budjet included contributions from the accretion of solids on the cores, whose rates were self-consistently computed with a 1D planet formation code. At this stage of the planet's growth, gravitational energy released in the envelope by solids' accretion far exceeds that released by gas accretion. These models are used to determine the gravitational torques exerted by the disk's gas on the planet and the resulting orbital migration rates. Since the envelope radius is a direct product of the models, they allow for a non-ambiguous assessment of the torques exerted by gas not bound to the planet. Additionally, since planets' envelopes are fully resolved, thermal and dynamical effects on the surrounding disk's gas are accurately taken into account. The computed migration rates are compared to those obtained from existing semi-analytical formulations for planets orbiting in isothermal and adiabatic disks. Because these formulations do not account for

  13. Toward a Galactic Distribution of Planets. I. Methodology and Planet Sensitivities of the 2015 High-cadence Spitzer Microlens Sample

    Science.gov (United States)

    Zhu, Wei; Udalski, A.; Calchi Novati, S.; Chung, S.-J.; Jung, Y. K.; Ryu, Y.-H.; Shin, I.-G.; Gould, A.; Lee, C.-U.; Albrow, M. D.; Yee, J. C.; Han, C.; Hwang, K.-H.; Cha, S.-M.; Kim, D.-J.; Kim, H.-W.; Kim, S.-L.; Kim, Y.-H.; Lee, Y.; Park, B.-G.; Pogge, R. W.; KMTNet Collaboration; Poleski, R.; Mróz, P.; Pietrukowicz, P.; Skowron, J.; Szymański, M. K.; Kozłowski, S.; Ulaczyk, K.; Pawlak, M.; OGLE Collaboration; Beichman, C.; Bryden, G.; Carey, S.; Fausnaugh, M.; Gaudi, B. S.; Henderson, C. B.; Shvartzvald, Y.; Wibking, B.; Spitzer Team

    2017-11-01

    We analyze an ensemble of microlensing events from the 2015 Spitzer microlensing campaign, all of which were densely monitored by ground-based high-cadence survey teams. The simultaneous observations from Spitzer and the ground yield measurements of the microlensing parallax vector {{\\boldsymbol{π }}}{{E}}, from which compact constraints on the microlens properties are derived, including ≲25% uncertainties on the lens mass and distance. With the current sample, we demonstrate that the majority of microlenses are indeed in the mass range of M dwarfs. The planet sensitivities of all 41 events in the sample are calculated, from which we provide constraints on the planet distribution function. In particular, assuming a planet distribution function that is uniform in {log}q, where q is the planet-to-star mass ratio, we find a 95% upper limit on the fraction of stars that host typical microlensing planets of 49%, which is consistent with previous studies. Based on this planet-free sample, we develop the methodology to statistically study the Galactic distribution of planets using microlensing parallax measurements. Under the assumption that the planet distributions are the same in the bulge as in the disk, we predict that ∼1/3 of all planet detections from the microlensing campaigns with Spitzer should be in the bulge. This prediction will be tested with a much larger sample, and deviations from it can be used to constrain the abundance of planets in the bulge relative to the disk.

  14. Multiple equilibria on planet Dune: Climate-vegetation dynamics on a sandy planet

    NARCIS (Netherlands)

    Cresto Aleina, F.; Baudena, M.; D' Andrea, F.; Provenzale, A

    2013-01-01

    We study the interaction between climate and vegetation on an ideal water-limited planet, focussing on the influence of vegetation on the global water cycle. We introduce a simple mechanistic box model consisting in a two-layer representation of the atmosphere and a two-layer soil scheme. The model

  15. Habitable Planets with Dynamic System of Global Air-Liquid-Solid Planet and Life

    Science.gov (United States)

    Miura, Y.; Kato, T.

    2017-11-01

    Habitable zone is dynamic three phase states (air-liquid-solid), which will be obtained in water-planet with volatile exchanges. Water and carbon-bearing grains at older extraterrestrial stones suggest that there are no global ocean water system.

  16. What makes a planet habitable, and how to search for habitable planets in other solar systems.

    Science.gov (United States)

    Papagiannis, M D

    1992-06-01

    The availability of liquid water is the most important factor that makes a planet habitable, because water is a very effective polar molecule and hence an excellent solvent and facilitator for the complex chemistry of life. Its presence presupposes a planet with a significant mass that guarantees the presence of a substantial atmosphere, and a reasonable spinning rate to avoid overheating. It also implies that the planet is at moderate distances from its central star, a range that is called the Ecosphere or the Habitable Zone. Since the evolution of life to high intelligence seems to take billions of years, it requires also that the central star must be neither too massive, that will produce a lot of lethal UV radiation and will have too short a life-span to allow life to evolve, nor of very small mass which will be producing too feeble a radiation to sustain life. The detection of free Oxygen in the atmosphere of a planet is a very strong evidence for the presence of life, because Oxygen is highly reactive and would rapidly disappear by combining with other elements, unless it is continuously replenished by life as the by-product of the process of photosynthesis that builds food for life (sugars) from CO2 and H2O.

  17. A young massive planet in a star-disk system.

    Science.gov (United States)

    Setiawan, J; Henning, Th; Launhardt, R; Müller, A; Weise, P; Kürster, M

    2008-01-03

    There is a general consensus that planets form within disks of dust and gas around newly born stars. Details of their formation process, however, are still a matter of ongoing debate. The timescale of planet formation remains unclear, so the detection of planets around young stars with protoplanetary disks is potentially of great interest. Hitherto, no such planet has been found. Here we report the detection of a planet of mass (9.8+/-3.3)M(Jupiter) around TW Hydrae (TW Hya), a nearby young star with an age of only 8-10 Myr that is surrounded by a well-studied circumstellar disk. It orbits the star with a period of 3.56 days at 0.04 au, inside the inner rim of the disk. This demonstrates that planets can form within 10 Myr, before the disk has been dissipated by stellar winds and radiation.

  18. Constraints on a second planet in the WASP-3 system

    Energy Technology Data Exchange (ETDEWEB)

    Maciejewski, G.; Niedzielski, A.; Nowak, G.; Deka, B.; Adamów, M.; Górecka, M. [Centre for Astronomy, Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University, Grudziadzka 5, 87-100 Torun (Poland); Wolszczan, A. [Department of Astronomy and Astrophysics, The Pennsylvania State University, 525 Davey Laboratory, University Park, PA 16802 (United States); Neuhäuser, R.; Errmann, R.; Seeliger, M. [Astrophysikalisches Institut und Universitäts-Sternwarte, Schillergässchen 2-3, D-07745 Jena (Germany); Winn, J. N.; McKnight, L. [Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States); Fernández, M.; Aceituno, F. J. [Instituto de Astrofísica de Andalucía (IAA-CSIC), Glorieta de la Astronomía 3, E-18008 Granada (Spain); Ohlert, J. [Michael Adrian Observatorium, Astronomie Stiftung Trebur, D-65468 Trebur (Germany); Dimitrov, D. [Institute of Astronomy, Bulgarian Academy of Sciences, 72 Tsarigradsko Chausse Blvd., 1784 Sofia (Bulgaria); Latham, D. W.; Esquerdo, G. A.; Holman, M. J. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Jensen, E. L. N. [Department of Physics and Astronomy, Swarthmore College, Swarthmore, PA 19081 (United States); and others

    2013-12-01

    There have been previous hints that the transiting planet WASP-3b is accompanied by a second planet in a nearby orbit, based on small deviations from strict periodicity of the observed transits. Here we present 17 precise radial velocity (RV) measurements and 32 transit light curves that were acquired between 2009 and 2011. These data were used to refine the parameters of the host star and transiting planet. This has resulted in reduced uncertainties for the radii and masses of the star and planet. The RV data and the transit times show no evidence for an additional planet in the system. Therefore, we have determined the upper limit on the mass of any hypothetical second planet, as a function of its orbital period.

  19. Autonomous Observing and Planet Discovery with the Automated Planet Finder (APF)

    Science.gov (United States)

    Burt, Jennifer; Hanson, Russell; Holden, Bradford; Butler, R. Paul; Vogt, Steven S.; Laughlin, Greg

    2015-01-01

    The Automated Planet Finder (APF) is a dedicated, ground-based precision radial velocity facility located at Lick Observatory, operated by University of California Observatories (UCO). The 2.4-m telescope and accompanying high-resolution echelle spectrograph were specifically designed for the purpose of detecting planets in the habitable zone of low-mass stars. The telescope is operated every night (weather permitting) to achieve meaningful signal-to-noise gains from high cadence observing and to avoid the aliasing problems inherent to planets whose periods are close to the lunar month.The APF has been taking science quality data for over a year and has contributed to two planet discovery papers with data at a 1 m/s level of precision. The detection of these planets, especially the Uranus mass planet around GL687, indicates that the APF telescope is well suited to the discovery of low-mass planets orbiting low-mass stars in the as-yet relatively un-surveyed region of the sky near the north celestial pole.To take full advantage of the consistent influx of data it is necessary to analyze each night's results before deciding the next evening's targets. We are in the process of developing a fully automated reduction pipeline that will take data from raw FITS files to final radial velocity values and integrate those values into a master database. The database is then run through the publicly available Systemic console, a publically available software package for the analysis and combined multiparameter fitting of Doppler radial velocity observations. Systemic will re-calculate the possibility of planetary signals in the data and use this value, along with other considerations such as the star's brightness and chromospheric activity level, to assign it a priority rating for future observations.When the telescope is again on sky it uses a suite of stellar and atmospheric calibrations derived from the part year's observations to calculate the expected exposure time for

  20. PLANET TOPERS: Planets, Tracing the Transfer, Origin, Preservation, and Evolution of their ReservoirS

    Science.gov (United States)

    Dehant, Veronique; Breuer, Doris; Claeys, Philippe; Debaille, Vinciane; De Keyser, Johan; Javaux, Emmanuelle; Goderis, Steven; Karatekin, Ozgur; Mattielli, Nadine; Noack, Lena; Spohn, Tilman; Carine Vandaele, Ann; Vanhaecke, Frank; Van Hoolst, Tim; Wilquet, Valerie

    2013-04-01

    The PLANET TOPERS (Planets, Tracing the Transfer, Origin, Preservation, and Evolution of their ReservoirS) group is an Inter-university attraction pole (IAP) addressing the question of habitability in our Solar System. Habitability is commonly understood as "the potential of an environment (past or present) to support life of any kind" (Steele et al., 2005, http://mepag.jpl.nasa.gov/reports/archive.html). Based on the only known example of Earth, the concept refers to whether environmental conditions are available that could eventually support life, even if life does not currently exist (Javaux and Dehant, 2010, Astron. Astrophys. Rev., 18, 383-416, DOI: 10.1007/s00159-010-0030-4). Life includes properties such as consuming nutrients and producing waste, the ability to reproduce and grow, pass on genetic information, evolve, and adapt to the varying conditions on a planet (Sagan, 1970, Encyclopedia Britannica, 22, 964-981). Terrestrial life requires liquid water. The stability of liquid water at the surface of a planet defines a habitable zone (HZ) around a star. In the Solar System, it stretches between Venus and Mars, but excludes these two planets. If the greenhouse effect is taken into account, the habitable zone may have included early Mars while the case for Venus is still debated. Important geodynamic processes affect the habitability conditions of a planet. As envisaged by the group, this IAP develops and closely integrates the geophysical, geological, and biological aspects of habitability with a particular focus on Earth neighboring planets, Mars and Venus. It works in an interdisciplinary approach to understand habitability and in close collaboration with another group, the Helmholtz Alliance "Life and Planet Evolution", which has similar objectives. The dynamic processes, e.g. internal dynamo, magnetic field, atmosphere, plate tectonics, mantle convection, volcanism, thermo-tectonic evolution, meteorite impacts, and erosion, modify the planetary surface

  1. Urey Prize Lecture: Binary Minor Planets

    Science.gov (United States)

    Margot, J. L.

    2004-11-01

    The discovery of binary systems in the near-Earth, main belt, and Kuiper belt populations provides an abundance of new data that expand our knowledge of the physics and chemistry of the solar system. Binary minor planets form as a result of collisional, tidal, and capture processes that are important to study as they play major roles in the formation and evolution of planetary systems. The frequency of occurrence of such processes directly reflects the dynamical environment in the various populations. Observations of binaries provide a powerful way to measure the bulk properties of small bodies, which in turn lead to inferences about their composition and internal structure. These data may offer a rare glimpse of what physical and chemical conditions prevailed when protoplanets formed, and what subsequent evolution took place. In the case of the Kuiper Belt, the study of a handful of binaries forces us to rethink how dense and how bright these bodies are, and to significantly revise our current mass estimates for the entire population. The number of known binary minor planets has increased dramatically over the past few years, with roughly ten new discoveries each year. I will attempt to summarize recent developments, with examples drawn from my observations with the Hubble, Palomar, Keck, Arecibo and Goldstone telescopes.

  2. A Distant Planet: Finding Superman's Krypton

    Science.gov (United States)

    Ricca, B.

    2016-01-01

    In 2012, Neil deGrasse Tyson made headlines when he appeared in a Superman comic book and pinpointed a real planet (located in Corvus) that matched the description of Superman's homeworld, the fictional planet of Krypton. This story tracked all over the world. Why? I will look at the figure of Superman, whose backstory—orphan from an exploding planet—is somehow known by everyone from the age of eight on. I will look at how specific astronomical phenomena (in the sky and in the news) may have inspired Superman's young teenaged creators in the 1930s to create this iconic modern myth—a myth, like many, grounded in astronomy. My goal is to show that comics—which we normally think of as juvenile, throwaway entertainment— actually tried to base themselves (and certainly were inspired by) actual astronomical events in the thirties and forties, made more accessible to the public by new scientific explanations, including a real supernova that may have inspired the destruction of Krypton.

  3. Photometric Defocus Observations of Transiting Extrasolar Planets

    Directory of Open Access Journals (Sweden)

    Tobias C. Hinse

    2015-03-01

    Full Text Available We have carried out photometric follow-up observations of bright transiting extrasolar planets using the CbNUOJ 0.6 m telescope. We have tested the possibility of obtaining high photometric precision by applying the telescope defocus technique, allowing the use of several hundred seconds in exposure time for a single measurement. We demonstrate that this technique is capable of obtaining a root-mean-square scatter of sub-millimagnitude order over several hours for a V ~10 host star, typical for transiting planets detected from ground-based survey facilities. We compared our results with transit observations from a telescope operated in in-focus mode. High photometric precision was obtained due to the collection of a larger amount of photons, resulting in a higher signal compared to other random and systematic noise sources. Accurate telescope tracking is likely to further contribute to lowering systematic noise by exposing the same pixels on the CCD. Furthermore, a longer exposure time helps reduce the effect of scintillation noise which otherwise has a significant effect for small-aperture telescopes operated in in-focus mode. Finally we present the results of modelling four light-curves in which a root-mean-square scatter of 0.70 to 2.3 milli-magnitudes was achieved.

  4. Nicolaus Copernicus - Making the Earth a Planet

    Science.gov (United States)

    Gingerich, Owen; MacLachlan, James

    2005-06-01

    Born in Poland in 1473, Nicolaus Copernicus launched a quiet revolution. No scientist so radically transformed our understanding of our place in the universe as this curious bishop's doctor and church official. In his quest to discover a beautiful and coherent system to describe the motions of the planets, Copernicus placed the sun in the center of the system and made the earth a planet traveling around the sun. Today it is hard to imagine our solar system any other way, but for his time Copernicus's idea was earthshaking. In 1616 the church banned his book Revolutions because it contradicted the accepted notion that God placed Earth in the center of the universe. Even though those who knew of his work considered his idea dangerous, Revolutions remained of interest only to other scientists for many years. It took almost two hundred years for his concept of a sun-centered system to reach the general public. None the less, what Copernicus set out in his remarkable text truly revolutionized science. For this, Copernicus, a quiet doctor who made a tremendous leap of imagination, is considered the father of the Scientific Revolution.

  5. Probing Planets in Extragalactic Galaxies Using Quasar Microlensing

    OpenAIRE

    Dai, Xinyu; Guerras, Eduardo

    2018-01-01

    Previously, planets have been detected only in the Milky Way galaxy. Here, we show that quasar microlensing provides a means to probe extragalactic planets in the lens galaxy, by studying the microlensing properties of emission close to the event horizon of the supermassive black hole of the background quasar, using the current generation telescopes. We show that a population of unbound planets between stars with masses ranging from Moon to Jupiter masses is needed to explain the frequent Fek...

  6. ESPRI: Astrometric planet search with PRIMA at the VLTI

    Directory of Open Access Journals (Sweden)

    Ségransan D.

    2011-07-01

    Full Text Available The ESPRI consortium will conduct an astrometric survey for extrasolar planets, using the PRIMA facility at the Very Large Telescope Interferometer. Our scientific goals include determining orbital inclinations and masses for planets already known from radial-velocity surveys, searches for planets around nearby stars of all masses, and around young stars. The consortium has built the PRIMA differential delay lines, developed an astrometric operation and calibration plan, and will deliver astrometric data reduction software.

  7. White dwarf pollution by planets in stellar binaries

    OpenAIRE

    Hamers, S.; Portegies, F, Zwart S.

    2016-01-01

    Approximately $0.2 \\pm 0.2$ of white dwarfs (WDs) show signs of pollution by metals, which is likely due to the accretion of tidally disrupted planetary material. Models invoking planet-planet interactions after WD formation generally cannot explain pollution at cooling times of several Gyr. We consider a scenario in which a planet is perturbed by Lidov-Kozai oscillations induced by a binary companion and exacerbated by stellar mass loss, explaining pollution at long cooling times. Our comput...

  8. A 1.9 Earth Radius Rocky Planet and the Discovery of a Non-transiting Planet in the Kepler-20 System

    Science.gov (United States)

    Buchhave, Lars A.; Dressing, Courtney D.; Dumusque, Xavier; Rice, Ken; Vanderburg, Andrew; Mortier, Annelies; Lopez-Morales, Mercedes; Lopez, Eric; Lundkvist, Mia S.; Kjeldsen, Hans; Affer, Laura; Bonomo, Aldo S.; Charbonneau, David; Collier Cameron, Andrew; Cosentino, Rosario; Figueira, Pedro; Fiorenzano, Aldo F. M.; Harutyunyan, Avet; Haywood, Raphaëlle D.; Johnson, John Asher; Latham, David W.; Lovis, Christophe; Malavolta, Luca; Mayor, Michel; Micela, Giusi; Molinari, Emilio; Motalebi, Fatemeh; Nascimbeni, Valerio; Pepe, Francesco; Phillips, David F.; Piotto, Giampaolo; Pollacco, Don; Queloz, Didier; Sasselov, Dimitar; Ségransan, Damien; Sozzetti, Alessandro; Udry, Stéphane; Watson, Chris

    2016-12-01

    Kepler-20 is a solar-type star (V = 12.5) hosting a compact system of five transiting planets, all packed within the orbital distance of Mercury in our own solar system. A transition from rocky to gaseous planets with a planetary transition radius of ˜1.6 {R}\\oplus has recently been proposed by several articles in the literature. Kepler-20b ({R}p ˜ 1.9 {R}\\oplus ) has a size beyond this transition radius; however, previous mass measurements were not sufficiently precise to allow definite conclusions to be drawn regarding its composition. We present new mass measurements of three of the planets in the Kepler-20 system that are facilitated by 104 radial velocity measurements from the HARPS-N spectrograph and 30 archival Keck/HIRES observations, as well as an updated photometric analysis of the Kepler data and an asteroseismic analysis of the host star ({M}\\star = 0.948+/- 0.051 {M}⊙ and {R}\\star = 0.964+/- 0.018 {R}⊙ ). Kepler-20b is a {1.868}-0.034+0.066 {R}\\oplus planet in a 3.7 day period with a mass of {9.70}-1.44+1.41 {M}\\oplus , resulting in a mean density of {8.2}-1.3+1.5 {{g}} {{cm}}-3, indicating a rocky composition with an iron-to-silicate ratio consistent with that of the Earth. This makes Kepler-20b the most massive planet with a rocky composition found to date. Furthermore, we report the discovery of an additional non-transiting planet with a minimum mass of {19.96}-3.61+3.08 {M}\\oplus and an orbital period of ˜34 days in the gap between Kepler-20f (P ˜ 11 days) and Kepler-20d (P ˜ 78 days). Based on observations made with the Italian Telescopio Nazionale Galileo (TNG) operated on the island of La Palma by the Fundación Galileo Galilei of the INAF (Istituto Nazionale di Astrofísica) at the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofísica de Canarias.

  9. Star-Planet Interactions in X-rays

    OpenAIRE

    Poppenhaeger, K.

    2010-01-01

    We investigated the coronal activity of planet-hosting stars by means of statistical analysis for a complete sample of stars in the solar neighborhood. We find no observational evidence that Star-Planet Interactions are at work in this sample, at least not at the sensitivity levels of our observations. We additionally test the upsilon Andromedae system, an F8V star with a Hot Jupiter and two other known planets, for signatures of Star-Planet Interactions in the chromosphere, but only detect v...

  10. Reading the Signatures of Extrasolar Planets in Debris Disks

    Science.gov (United States)

    Kuchner, Marc J.

    2009-01-01

    An extrasolar planet sculpts the famous debris dish around Fomalhaut; probably ma ny other debris disks contain planets that we could locate if only we could better recognize their signatures in the dust that surrounds them. But the interaction between planets and debris disks involves both orbital resonances and collisions among grains and rocks in the disks --- difficult processes to model simultanemus]y. I will describe new 3-D models of debris disk dynamics that incorporate both collisions and resonant trapping of dust for the first time, allowing us to decode debris disk images and read the signatures of the planets they contain.

  11. On the dynamical habitability of Trojan planets in exoplanetary systems

    Science.gov (United States)

    Schwarz, R.; Funk, B.; Bazsó, Á.; Eggl, S.

    2017-03-01

    Besides the hierarchical configurations exoplanets have been observed in so far, Earth-analogs can theoretically exist in co-orbital motion with giant planets. Those so-called Trojan planets share the same orbit as their Jovian hosts, trailing or leading by approximately 60 degrees in mean anomaly. If a giant planet was situated in the habitable zone (HZ) of an exoplanetary system coorbital terrestrial worlds could in principle also be habitable provided their orbits are "tame enough". In this paper, we study the dynamical properties of Earth-like Trojan planets in their host stars' respective HZs. We investigate the orbital stability of possible Trojan planets near the Lagrangian equilibrium points L_4 and L_5 for several candidate systems. Our numerical simulations have been carried out using the planar three-body problem, in case the extrasolar system contains only one known planet and the n-body problem with more than one planet in the system. We study the stability region around the equilibrium points and counted the number of stable orbits concentrating on the dependencies between the semimajor axis, the eccentricity and the argument of perihelion of the Trojan planet. We found that of the investigated 14 systems 6 support stable Trojan planets in the system's HZ, namely HD 5891, HD 28185, WASP-41, HD 11755, HD 221287 and HD 13908.

  12. A resonant chain of four transiting, sub-Neptune planets.

    Science.gov (United States)

    Mills, Sean M; Fabrycky, Daniel C; Migaszewski, Cezary; Ford, Eric B; Petigura, Erik; Isaacson, Howard

    2016-05-26

    Surveys have revealed many multi-planet systems containing super-Earths and Neptunes in orbits of a few days to a few months. There is debate whether in situ assembly or inward migration is the dominant mechanism of the formation of such planetary systems. Simulations suggest that migration creates tightly packed systems with planets whose orbital periods may be expressed as ratios of small integers (resonances), often in a many-planet series (chain). In the hundreds of multi-planet systems of sub-Neptunes, more planet pairs are observed near resonances than would generally be expected, but no individual system has hitherto been identified that must have been formed by migration. Proximity to resonance enables the detection of planets perturbing each other. Here we report transit timing variations of the four planets in the Kepler-223 system, model these variations as resonant-angle librations, and compute the long-term stability of the resonant chain. The architecture of Kepler-223 is too finely tuned to have been formed by scattering, and our numerical simulations demonstrate that its properties are natural outcomes of the migration hypothesis. Similar systems could be destabilized by any of several mechanisms, contributing to the observed orbital-period distribution, where many planets are not in resonances. Planetesimal interactions in particular are thought to be responsible for establishing the current orbits of the four giant planets in the Solar System by disrupting a theoretical initial resonant chain similar to that observed in Kepler-223.

  13. Transiting exoplanets: From planet statistics to their physical nature

    Directory of Open Access Journals (Sweden)

    Rauer H.

    2011-02-01

    Full Text Available The colloquium "Detection and Dynamics of Transiting Exoplanets" was held at the Observatoire de Haute-Provence and discussed the status of transiting exoplanet investigations in a 4.5 day meeting. Topics addressed ranged from planet detection, a discussion on planet composition and interior structure, atmospheres of hot-Jupiter planets, up to the effect of tides and the dynamical evolution of planetary systems. Here, I give a summary of the recent developments of transiting planet detections and investigations discussed at this meeting.

  14. Planet signatures in collisionally active debris discs: scattered light images

    Science.gov (United States)

    Thebault, P.; Kral, Q.; Ertel, S.

    2012-11-01

    Context. Planet perturbations have been often invoked as a potential explanation for many spatial structures that have been imaged in debris discs. So far this issue has been mostly investigated with pure N-body numerical models, which neglect the crucial effect collisions within the disc can have on the disc's response to dynamical perturbations. Aims: We numerically investigate how the coupled effect of collisions and radiation pressure can affect the formation and survival of radial and azimutal structures in a disc perturbed by a planet. We consider two different set-ups: a planet embedded within an extended disc and a planet exterior to an inner debris ring. One important issue we want to address is under which conditions a planet's signature can be observable in a collisionally active disc. Methods: We use our DyCoSS code, which is designed to investigate the structure of perturbed debris discs at dynamical and collisional steady-state, and derive synthetic images of the system in scattered light. The planet's mass and orbit, as well as the disc's collisional activity (parameterized by its average vertical optical depth τ0) are explored as free parameters. Results: We find that collisions always significantly damp planet-induced spatial structures. For the case of an embedded planet, the planet's signature, mostly a density gap around its radial position, should remain detectable in head-on images if Mplanet ≥ MSaturn. If the system is seen edge-on, however, inferring the presence of the planet is much more difficult, as only weak asymmetries remain in a collisionally active disc, although some planet-induced signatures might be observable under very favourable conditions. For the case of an inner ring and an external planet, planetary perturbations cannot prevent collision-produced small fragments from populating the regions beyond the ring. The radial luminosity profile exterior to the ring is in most cases close to the one it should have in the absence

  15. Workshop on Oxygen in the Terrestrial Planets

    Science.gov (United States)

    2004-01-01

    This volume contains abstracts that have been accepted for presentation at the Workshop on Oxygen in the Terrestrial Planets, July 20-23,2004, Santa Fe, New Mexico. The contents include: 1) Experimental Constraints on Oxygen and Other Light Element Partitioning During Planetary Core Formation; 2) In Situ Determination of Fe(3+)/SigmaFe of Spinels by Electron Microprobe: An Evaluation of the Flank Method; 3) The Effect of Oxygen Fugacity on Large-Strain Deformation and Recrystallization of Olivine; 4) Plagioclase-Liquid Trace Element Oxygen Barometry and Oxygen Behaviour in Closed and Open System Magmatic Processes; 5) Core Formation in the Earth: Constraints from Ni and Co; 6) Oxygen Isotopic Compositions of the Terrestrial Planets; 7) The Effect of Oxygen Fugacity on Electrical Conduction of Olivine and Implications for Earth s Mantle; 8) Redox Chemical Diffusion in Silicate Melts: The Impact of the Semiconductor Condition; 9) Ultra-High Temperature Effects in Earth s Magma Ocean: Pt and W Partitioning; 10) Terrestrial Oxygen and Hydrogen Isotope Variations: Primordial Values, Systematics, Subsolidus Effects, Planetary Comparisons, and the Role of Water; 11) Redox State of the Moon s Interior; 12) How did the Terrestrial Planets Acquire Their Water?; 13) Molecular Oxygen Mixing Ratio and Its Seasonal Variability in the Martian Atmosphere; 14) Exchange Between the Atmosphere and the Regolith of Mars: Discussion of Oxygen and Sulfur Isotope Evidence; 15) Oxygen and Hydrogen Isotope Systematics of Atmospheric Water Vapor and Meteoric Waters: Evidence from North Texas; 16) Implications of Isotopic and Redox Heterogeneities in Silicate Reservoirs on Mars; 17) Oxygen Isotopic Variation of the Terrestrial Planets; 18) Redox Exchanges in Hydrous Magma; 19) Hydrothermal Systems on Terrestrial Planets: Lessons from Earth; 20) Oxygen in Martian Meteorites: A Review of Results from Mineral Equilibria Oxybarometers; 21) Non-Linear Fractionation of Oxygen Isotopes Implanted in

  16. A Planet Soon to Meet Its Demise

    Science.gov (United States)

    Kohler, Susanna

    2017-02-01

    A tiny telescope has discovered a scalding hot world orbiting its star 1,300 light-years from us. KELT-16b may only be around for a few more hundreds of thousands of years, however.Dont Underestimate Tiny TelescopesThe KELT-North telescope in Arizona. This tiny telescope was responsible for the discovery of KELT-16b. [Vanderbilt University]In an era of ever larger observatories, you might think that theres no longer a place for small-aperture ground-based telescopes. But small ground-based telescopes have been responsible for the discovery and characterization of around 250 exoplanets so far and these are the targets that are especially useful for exoplanet science, as they aremore easily followed up than the faint discoveries made by telescopes like Kepler.The Kilogree Extremely Little Telescope (KELT) consists of two telescopes one in Arizona and one in South Africa that each have a 4.2-centimeter aperture. In total, KELT observes roughly 70% of the entire sky searching for planets transiting bright hosts. And its recently found quite an interesting one: KELT-16b. In a publication led by Thomas Oberst (Westminster College in Pennsylvania), a team of scientists presents their find.Combined follow-up light curves obtained for KELT-16b from 19 transits. The best-fit period is just under a day. [Oberst et al. 2017]A Hot WorldKELT-16b is whats known as a hot Jupiter. Using the KELT data and follow-up observations of 19 transits, Oberst and collaborators estimate KELT-16bs radius at roughly 1.4 times that of Jupiter and its mass at 2.75 times Jupiters. Its equilibrium temperature is a scalding 2453 K caused by the fact that it orbits so close to its host star that it completes each orbit in a mere 0.97 days!This short period is extremely unusual: there are only five other known transiting exoplanets with periods shorter than a day. KELT-16b is orbiting very close to its host, making it subject to extreme irradiation and strong tidal forces.Based on KELT-16bs orbit

  17. CONSTRAINING THE RADIATION AND PLASMA ENVIRONMENT OF THE KEPLER CIRCUMBINARY HABITABLE-ZONE PLANETS

    Energy Technology Data Exchange (ETDEWEB)

    Zuluaga, Jorge I. [Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138 (United States); Mason, Paul A. [New Mexico State University—DACC, Las Cruces, NM 88003 (United States); Cuartas-Restrepo, Pablo A. [FACom—Instituto de Física—FCEN, Universidad de Antioquia, Calle 70 No. 52-21, Medellín (Colombia)

    2016-02-20

    The discovery of many planets using the Kepler telescope includes 10 planets orbiting eight binary stars. Three binaries, Kepler-16, Kepler-47, and Kepler-453, have at least one planet in the circumbinary habitable zone (BHZ). We constrain the level of high-energy radiation and the plasma environment in the BHZ of these systems. With this aim, BHZ limits in these Kepler binaries are calculated as a function of time, and the habitability lifetimes are estimated for hypothetical terrestrial planets and/or moons within the BHZ. With the time-dependent BHZ limits established, a self-consistent model is developed describing the evolution of stellar activity and radiation properties as proxies for stellar aggression toward planetary atmospheres. Modeling binary stellar rotation evolution, including the effect of tidal interaction between stars in binaries, is key to establishing the environment around these systems. We find that Kepler-16 and its binary analogs provide a plasma environment favorable for the survival of atmospheres of putative Mars-sized planets and exomoons. Tides have modified the rotation of the stars in Kepler-47, making its radiation environment less harsh in comparison to the solar system. This is a good example of the mechanism first proposed by Mason et al. Kepler-453 has an environment similar to that of the solar system with slightly better than Earth radiation conditions at the inner edge of the BHZ. These results can be reproduced and even reparameterized as stellar evolution and binary tidal models progress, using our online tool http://bhmcalc.net.

  18. The Direct Detection and Characterization of M-dwarf Planets Using Light Echoes

    Science.gov (United States)

    Sparks, William B.; White, Richard L.; Lupu, Roxana E.; Ford, Holland C.

    2018-02-01

    Exoplanets orbiting M-dwarf stars are a prime target in the search for life in the universe. M-dwarf stars are active, with powerful flares that could adversely impact prospects for life, though there are counter-arguments. Here, we turn flaring to advantage and describe ways in which it can be used to enhance the detectability of planets, in the absence of transits or a coronagraph, significantly expanding the accessible discovery and characterization space. Flares produce brief bursts of intense luminosity, after which the star dims. Due to the light travel time between the star and planet, the planet receives the high-intensity pulse, which it re-emits through scattering (a light echo) or intrinsic emission when the star is much fainter, thereby increasing the planet’s detectability. The planet’s light-echo emission can potentially be discriminated from that of the host star by means of a time delay, Doppler shift, spatial shift, and polarization, each of which can improve the contrast of the planet to the star. Scattered light can reveal the albedo spectrum of the planet to within a size scale factor, and is likely to be polarized. Intrinsic emission mechanisms include fluorescent pumping of multiple molecular hydrogen and neutral oxygen lines by intense Lyα and Lyβ flare emission, recombination radiation of ionized and photodissociated species, and atmospheric processes such as terrestrial upper atmosphere airglow and near-infrared hydroxyl emission. We discuss the feasibility of detecting light echoes and find that light echo detection is possible under favorable circumstances.

  19. Two massive rocky planets transiting a K-dwarf 6.5 parsecs away

    Science.gov (United States)

    Gillon, Michaël; Demory, Brice-Olivier; Van Grootel, Valérie; Motalebi, Fatemeh; Lovis, Christophe; Cameron, Andrew Collier; Charbonneau, David; Latham, David; Molinari, Emilio; Pepe, Francesco A.; Ségransan, Damien; Sasselov, Dimitar; Udry, Stéphane; Mayor, Michel; Micela, Giuseppina; Piotto, Giampaolo; Sozzetti, Alessandro

    2017-03-01

    HD 219134 is a K-dwarf star at a distance of 6.5 parsecs around which several low-mass planets were recently discovered1,2. The Spitzer Space Telescope detected a transit of the innermost of these planets, HD 219134 b, whose mass and radius (4.5 M⊕ and 1.6 R⊕ respectively) are consistent with a rocky composition1. Here, we report new high-precision time-series photometry of the star acquired with Spitzer revealing that the second innermost planet of the system, HD 219134c, is also transiting. A global analysis of the Spitzer transit light curves and the most up-to-date HARPS-N velocity data set yields mass and radius estimations of 4.74 ± 0.19 M⊕ and 1.602 ± 0.055 R⊕ for HD 219134 b, and of 4.36 ± 0.22 M⊕ and 1.511 ± 0.047 R⊕ for HD 219134 c. These values suggest rocky compositions for both planets. Thanks to the proximity and the small size of their host star (0.778 ± 0.005 R⊙)3, these two transiting exoplanets — the nearest to the Earth yet found — are well suited for a detailed characterization (for example, precision of a few per cent on mass and radius, and constraints on the atmospheric properties) that could give important constraints on the nature and formation mechanism of the ubiquitous short-period planets of a few Earth masses.

  20. Minor Planet Center Data Processing Challenges

    Science.gov (United States)

    Rudenko, Michael

    2015-08-01

    The Minor Planet Center (MPC) is the single worldwide location for receipt and distribution of positional measurements of minor planets, comets and outer irregular natural satellites of the major planets. The MPC is responsible for the identification, designation and orbit computation for all of these objects.Over 2 million observations are received each month via the internet, and are validated and processed in near real time. The observations come in batches whose formats are checked and whose observations are run through a number of other routine checks such as departure from great circle motion, prior publication, single observations, near duplicates, etc. Some or all of a batch of observations may be returned to its sender if they fail one or more of the checks. After the observations have been validated, they are processed to produce orbits of newly discovered objects or used to update the orbits of known objects.Given the volume of observations, the sheer number of known objects against which to possibly match, the shortness of the time interval over which each object was likely observed, and the uncertainties in the positions, and occasionally possible errors in times, reported, a number of data processing challenges face the MPC. These include the following: Identifying observations of objects reported as new with already known objects; linking together sets of observations from different nights (possibly at different apparitions) which may belong to the same object; determining if a set of observations has been assigned to the wrong object; determining if an object with a very short arc is possibly a Near-Earth object; determining and examining the range of possible variant orbits of newly discovered Near-Earth objects with very short observation arcs for cases which indicate an object is potentially on a collision course with Earth; linking observations to known artificial satellites and/or booster stages and other space "junk"; prioritizing newly

  1. PLATO: a multiple telescope spacecraft for exo-planets hunting

    Science.gov (United States)

    Ragazzoni, Roberto; Magrin, Demetrio; Rauer, Heike; Pagano, Isabella; Nascimbeni, Valerio; Piotto, Giampaolo; Piazza, Daniele; Levacher, Patrick; Schweitzer, Mario; Basso, Stefano; Bandy, Timothy; Benz, Willy; Bergomi, Maria; Biondi, Federico; Boerner, Anko; Borsa, Francesco; Brandeker, Alexis; Brändli, Mathias; Bruno, Giordano; Cabrera, Juan; Chinellato, Simonetta; De Roche, Thierry; Dima, Marco; Erikson, Anders; Farinato, Jacopo; Munari, Matteo; Ghigo, Mauro; Greggio, Davide; Gullieuszik, Marco; Klebor, Maximilian; Marafatto, Luca; Mogulsky, Valery; Peter, Gisbert; Rieder, Martin; Sicilia, Daniela; Spiga, Daniele; Viotto, Valentina; Wieser, Matthias; Heras, Ana Maria; Gondoin, Philippe; Bodin, Pierre; Catala, Claude

    2016-07-01

    PLATO stands for PLAnetary Transits and Oscillation of stars and is a Medium sized mission selected as M3 by the European Space Agency as part of the Cosmic Vision program. The strategy behind is to scrutinize a large fraction of the sky collecting lightcurves of a large number of stars and detecting transits of exo-planets whose apparent orbit allow for the transit to be visible from the Earth. Furthermore, as the transit is basically able to provide the ratio of the size of the transiting planet to the host star, the latter is being characterized by asteroseismology, allowing to provide accurate masses, radii and hence density of a large sample of extra solar bodies. In order to be able to then follow up from the ground via spectroscopy radial velocity measurements these candidates the search must be confined to rather bright stars. To comply with the statistical rate of the occurrence of such transits around these kind of stars one needs a telescope with a moderate aperture of the order of one meter but with a Field of View that is of the order of 50 degrees in diameter. This is achieved by splitting the optical aperture into a few dozens identical telescopes with partially overlapping Field of View to build up a mixed ensemble of differently covered area of the sky to comply with various classes of magnitude stars. The single telescopes are refractive optical systems with an internally located pupil defined by a CaF2 lens, and comprising an aspheric front lens and a strong field flattener optical element close to the detectors mosaic. In order to continuously monitor for a few years with the aim to detect planetary transits similar to an hypothetical twin of the Earth, with the same revolution period, the spacecraft is going to be operated while orbiting around the L2 Lagrangian point of the Earth-Sun system so that the Earth disk is no longer a constraints potentially interfering with such a wide field continuous uninterrupted survey.

  2. Scenarios of giant planet formation and evolution and their impact on the formation of habitable terrestrial planets.

    Science.gov (United States)

    Morbidelli, Alessandro

    2014-04-28

    In our Solar System, there is a clear divide between the terrestrial and giant planets. These two categories of planets formed and evolved separately, almost in isolation from each other. This was possible because Jupiter avoided migrating into the inner Solar System, most probably due to the presence of Saturn, and never acquired a large-eccentricity orbit, even during the phase of orbital instability that the giant planets most likely experienced. Thus, the Earth formed on a time scale of several tens of millions of years, by collision of Moon- to Mars-mass planetary embryos, in a gas-free and volatile-depleted environment. We do not expect, however, that this clear cleavage between the giant and terrestrial planets is generic. In many extrasolar planetary systems discovered to date, the giant planets migrated into the vicinity of the parent star and/or acquired eccentric orbits. In this way, the evolution and destiny of the giant and terrestrial planets become intimately linked. This paper discusses several evolutionary patterns for the giant planets, with an emphasis on the consequences for the formation and survival of habitable terrestrial planets. The conclusion is that we should not expect Earth-like planets to be typical in terms of physical and orbital properties and accretion history. Most habitable worlds are probably different, exotic worlds.

  3. The CORALIE survey for southern extrasolar planets. XVII. New and updated long period and massive planets

    Science.gov (United States)

    Marmier, M.; Ségransan, D.; Udry, S.; Mayor, M.; Pepe, F.; Queloz, D.; Lovis, C.; Naef, D.; Santos, N. C.; Alonso, R.; Alves, S.; Berthet, S.; Chazelas, B.; Demory, B.-O.; Dumusque, X.; Eggenberger, A.; Figueira, P.; Gillon, M.; Hagelberg, J.; Lendl, M.; Mardling, R. A.; Mégevand, D.; Neveu, M.; Sahlmann, J.; Sosnowska, D.; Tewes, M.; Triaud, A. H. M. J.

    2013-03-01

    Context. Since 1998, a planet-search program around main sequence stars within 50 pc in the southern hemisphere has been carried out with the CORALIE echelle spectrograph at La Silla Observatory. Aims: With an observing time span of more than 14 years, the CORALIE survey is now able to unveil Jovian planets on Jupiter's period domain. This growing period-interval coverage is important for building formation and migration models since observational constraints are still weak for periods beyond the ice line. Methods: Long-term precise Doppler measurements with the CORALIE echelle spectrograph, together with a few additional observations made with the HARPS spectrograph on the ESO 3.6 m telescope, reveal radial velocity signatures of massive planetary companions on long-period orbits. Results: In this paper we present seven new planets orbiting HD 27631, HD 98649, HD 106515A, HD 166724, HD 196067, HD 219077, and HD 220689, together with the CORALIE orbital parameters for three already known planets around HD 10647, HD 30562, and HD 86226. The period range of the new planetary companions goes from 2200 to 5500 days and covers a mass domain between 1 and 10.5 MJup. Surprisingly, five of them present very high eccentricities above e > 0.57. A pumping scenario by Kozai mechanism may be invoked for HD 106515Ab and HD 196067b, which are both orbiting stars in multiple systems. Since the presence of a third massive body cannot be inferred from the data of HD 98649b, HD 166724b, and HD 219077b, the origin of the eccentricity of these systems remains unknown. Except for HD 10647b, no constraint on the upper mass of the planets is provided by Hipparcos astrometric data. Finally, the hosts of these long period planets show no metallicity excess. The CORALIE radial velocity measurements discussed in this paper are only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/551/A90Based on observations

  4. Observational evidence for two distinct giant planet populations

    Science.gov (United States)

    Santos, N. C.; Adibekyan, V.; Figueira, P.; Andreasen, D. T.; Barros, S. C. C.; Delgado-Mena, E.; Demangeon, O.; Faria, J. P.; Oshagh, M.; Sousa, S. G.; Viana, P. T. P.; Ferreira, A. C. S.

    2017-07-01

    Context. Analysis of the statistical properties of exoplanets, together with those of their host stars, are providing a unique view into the process of planet formation and evolution. Aims: In this paper we explore the properties of the mass distribution of giant planet companions to solar-type stars, in a quest for clues about their formation process. Methods: With this goal in mind we studied, with the help of standard statistical tests, the mass distribution of giant planets using data from the exoplanet.eu catalog and the SWEET-Cat database of stellar parameters for stars with planets. Results: We show that the mass distribution of giant planet companions is likely to present more than one population with a change in regime around 4 MJup. Above this value host stars tend to be more metal poor and more massive and have [Fe/H] distributions that are statistically similar to those observed in field stars of similar mass. On the other hand, stars that host planets below this limit show the well-known metallicity-giant planet frequency correlation. Conclusions: We discuss these results in light of various planet formation models and explore the implications they may have on our understanding of the formation of giant planets. In particular, we discuss the possibility that the existence of two separate populations of giant planets indicates that two different processes of formation are at play. A table with the planet and stellar parameters is only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/603/A30

  5. Planet-disc interaction in laminar and turbulent discs

    Science.gov (United States)

    Stoll, Moritz H. R.; Picogna, Giovanni; Kley, Wilhelm

    2017-07-01

    In weakly ionised discs turbulence can be generated through the vertical shear instability (VSI). Embedded planets are affected by a stochastic component in the torques acting on them, which can impact their migration. In this work we study the interplay between a growing planet embedded in a protoplanetary disc and the VSI turbulence. We performed a series of 3D hydrodynamical simulations for locally isothermal discs with embedded planets in the mass range from 5 to 100 Earth masses. We study planets embedded in an inviscid disc that is VSI unstable, becomes turbulent, and generates angular momentum transport with an effective α = 5 × 10-4. This is compared to the corresponding viscous disc using exactly this α-value. In general we find that the planets have only a weak impact on the disc turbulence. Only for the largest planet (100 M⊕) does the turbulent activity become enhanced inside of the planet. The depth and width of a gap created by the more massive planets (30,100 M⊕) in the turbulent disc equal exactly that of the corresponding viscous case, leading to very similar torque strengths acting on the planet, with small stochastic fluctuations for the VSI disc. At the gap edges vortices are generated that are stronger and longer-lived in the VSI disc. Low mass planets (with Mp ≤ 10 M⊕) do not open gaps in the disc in either case, but generate for the turbulent disc an overdensity behind the planet that exerts a significant negative torque. This can boost the inward migration in VSI turbulent discs well above the Type I rate. Owing to the finite turbulence level in realistic 3D discs the gap depth will always be limited and migration will not stall in inviscid discs.

  6. Limits to the presence of transiting circumbinary planets in CoRoT Data

    Science.gov (United States)

    Klagyivik, P.; Deeg, H. J.; Cabrera, J.; Csizmadia, Sz.; Almenara, J. M.

    2017-06-01

    Aims: During its flight phase, from 2007-2012, the CoRoT mission delivered light curves for over 2000 eclipsing binaries. Data from the Kepler mission have proven the existence of several transiting circumbinary planets. While light curves from CoRoT typically have lower precision and shorter coverage, the number of CoRoT targets is similar to that of Kepler and some of the known circumbinary planets could potentially be detected in CoRoT data as well. The aim of this work was to reanalyse the entire CoRoT Data set to search for the presence of circumbinary planets and to derive limits on the abundances of such planets. Methods: We developed a code that removes the signatures of eclipsing binaries from the light curves, and searches for quasi-periodic, transit-like features in the light curves after removal of binary eclipses and instrumental features. The code requires little information on sample systems and can also be used for other space missions, such as Kepler, K2, TESS, and PLATO. The code is broad in the requirements leading to detections, but was tuned to deliver an amount of detections that are manageable in a subsequent, mainly visual, assessment of their origin. Results: We identified three planet candidates in the CoRoT sample whose transits would have arisen from a single pass across the central binary; however, no candidates with transit events from multiple planetary orbits remained. We calculated the upper limits for the number of Jupiter, Saturn-, and Neptune-sized planets in co-planar orbits for different orbital period ranges. We found that there are much fewer giant planets in short periodic orbits around close binary systems than around single stars. Full Table 1 is only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/602/A117

  7. Planet-wide sand motion on mars

    Science.gov (United States)

    Bridges, N.T.; Bourke, M.C.; Geissler, P.E.; Banks, M.E.; Colon, C.; Diniega, S.; Golombek, M.P.; Hansen, C.J.; Mattson, S.; McEwen, A.S.; Mellon, M.T.; Stantzos, N.; Thomson, B.J.

    2012-01-01

    Prior to Mars Reconnaissance Orbiter data, images of Mars showed no direct evidence for dune and ripple motion. This was consistent with climate models and lander measurements indicating that winds of sufficient intensity to mobilize sand were rare in the low-density atmosphere. We show that many sand ripples and dunes across Mars exhibit movement of as much as a few meters per year, demonstrating that Martian sand migrates under current conditions in diverse areas of the planet. Most motion is probably driven by wind gusts that are not resolved in global circulation models. A past climate with a thicker atmosphere is only required to move large ripples that contain coarse grains. ?? 2012 Geological Society of America.

  8. Geology and Habitability of Terrestrial Planets

    CERN Document Server

    Fishbaugh, Kathryn E; Raulin, François; Marais, David J; Korablev, Oleg

    2007-01-01

    Given the fundamental importance of and universal interest in whether extraterrestrial life has developed or could eventually develop in our solar system and beyond, it is vital that an examination of planetary habitability goes beyond simple assumptions such as, "Where there is water, there is life." This book has resulted from a workshop at the International Space Science Institute (ISSI) in Bern, Switzerland (5-9 September 2005) that brought together planetary geologists, geophysicists, atmospheric scientists, and biologists to discuss the multi-faceted problem of how the habitability of a planet co-evolves with the geology of the surface and interior, the atmosphere, and the magnetosphere. Each of the six chapters has been written by authors with a range of expertise so that each chapter is itself multi-disciplinary, comprehensive, and accessible to scientists in all disciplines. These chapters delve into what life needs to exist and ultimately to thrive, the early environments of the young terrestrial pl...

  9. Spectral Astrometry Mission for Planets Detection

    Energy Technology Data Exchange (ETDEWEB)

    Erskine, D J; Edelstein, J

    2002-08-09

    The Spectral Astrometry Mission is a space-mission concept that uses simultaneous, multiple-star differential astrometry to measure exo-solar planet masses. The goal of SAM is to measure the reflex motions of hundreds of nearby ({approx}50 pc) F, G and K stars, relative to adjacent stars, with a resolution of 2.5 {micro}-arcsec. SAM is a new application of Spectral Interferometry (SI), also called Externally Dispersed Interferometry (EDI), that can simultaneously measure the angular difference between the target and multiple reference stars. SI has demonstrated the ability to measure a {lambda}/20,000 white-light fringe shift with only {lambda}/3 baseline control. SAM's structural stability and compensation requirements are therefore dramatically reduced compared to existing long-arm balanced-arm interferometric astrometry methods. We describe the SAM's mission concept, long-baseline SI astrometry method, and technical challenges to achieving the mission.

  10. The magnetodiscs and aurorae of giant planets

    CERN Document Server

    Achilleos, Nicholas; Arridge, Chris; Badman, Sarah; Delamere, Peter; Grodent, Denis; Kivelson, Margaret; Louarn, Philippe

    2016-01-01

    Readers will find grouped together here the most recent observations, current theoretical models and present understanding of the coupled atmosphere, magnetosphere and solar wind system. The book begins with a general discussion of mass, energy and momentum transport in magnetodiscs. The physics of partially ionized plasmas of the giant planet magnetodiscs is of general interest throughout the field of space physics, heliophysics and astrophysical plasmas; therefore, understanding the basic physical processes associated with magnetodiscs has universal applications. The second chapter characterizes the solar wind interaction and auroral responses to solar wind driven dynamics. The third chapter describes the role of magnetic reconnection and the effects on plasma transport. Finally, the last chapter characterizes the spectral and spatial properties of auroral emissions, distinguishing between solar wind drivers and internal driving mechanisms. The in-depth reviews provide an excellent reference for future re...

  11. Uranus - The planet, rings and satellites

    Science.gov (United States)

    Miner, Ellis D.

    The present overview of available data regarding Uranus and its planetary structures encompasses ground- and space-based observations of the planet with specific attention given to the interpretation of Voyager 2 data. A brief examination of historical observations is given which includes its discovery, position determination, and the related discoveries of Uranus' five large satellites and rings. The observational data preceding the Voyager 2 mission are reviewed in terms of the planetary interior, atmosphere, and magnetosphere. The Voyager 2 mission is given detailed treatment with descriptions of NASA's development and deployment of the spacecraft as well as detailed data from the Uranus encounter. Reference is given to structure and composition of Uranus' atmosphere, valid models of the interior, and wave-particle interactions in the magnetosphere. The structures of the rings and satellites are examined with reference to specific observational requirements from future missions.

  12. Energy conversion processes in the outer planets

    Science.gov (United States)

    Gierasch, P. J.; Conrath, B. J.

    1985-01-01

    Energy conversion processes which are potentially important in the outer planets at pressures greater than obut 0.1 bar are reviewed. Generation of buoyancy contrasts by condensation of various constituents is discussed with emphasis on the possible significance of phase changes in substances such as Si and Mg compounds at deep levels. It is demonstrated that, in the absence of nonequilibrium thermodynamic processes, strong kinetic energy generation must accompany the transport of heat out of the high temperature planetary interiors. The possibly dominant role of lagged parahydrogen conversion in the convective transport of heat at levels where T is less than 300 K is discussed. Measurements which may ultimately contribute to a better understanding of energy conversion processes are summarized.

  13. Setting the Stage for Habitable Planets

    Science.gov (United States)

    Gonzalez, Guillermo

    2014-01-01

    Our understanding of the processes that are relevant to the formation and maintenance of habitable planetary systems is advancing at a rapid pace, both from observation and theory. The present review focuses on recent research that bears on this topic and includes discussions of processes occurring in astrophysical, geophysical and climatic contexts, as well as the temporal evolution of planetary habitability. Special attention is given to recent observations of exoplanets and their host stars and the theories proposed to explain the observed trends. Recent theories about the early evolution of the Solar System and how they relate to its habitability are also summarized. Unresolved issues requiring additional research are pointed out, and a framework is provided for estimating the number of habitable planets in the Universe. PMID:25370028

  14. The Planets Testbed: Science for Digital Preservation

    Directory of Open Access Journals (Sweden)

    Seamus Ross

    2008-06-01

    Full Text Available The preservation of digital objects requires specific software tools or services. These can be characterisation tools that abstract the essential characteristics of a digital object from a file, migration tools that convert digital objects to different formats, or emulation tools that render digital objects in their original context on a new infrastructure. Until recently digital preservation has been characterised by practices and processes that could best be described as more art and craft than science. The Planets Testbed provides a controlled environment where preservation tools can be tested and evaluated, and where experiment results can be empirically compared. This paper presents an overview of the Testbed application, an analysis of the experiment methodology and a description of the Testbed's web service approach.

  15. Exploring the veiled planet. [Venus observations

    Science.gov (United States)

    1980-01-01

    An overview of data obtained from various experiments which characterize geological features and atmospheric properties of Venus is presented. Data from the two Pioneer sounder probes (one located at Venus's equator and the other near the north pole) exhibit a reversal in the equator-to-pole temperature patterns at 60 km altitude which suggests that two circulation cells exist within the atmospheric region. However, the atmospheric temperature and pressure beneath the clouds are found to be nearly identical everywhere on Venus and both temperature and pressure conditions at the surface are lower than first expected. The identification of sulphur dioxide clouds which appear to coincide with Venus's characteristic global patterns of C- and Y-shaped dark markings support the hypothesis of a regular pattern of planet spanning breaks in the upper cloud layer. Explanations of a Venus sulphur cycle and of observed magnetic field structures are suggested

  16. Extrasolar planets and their host stars

    CERN Document Server

    von Braun, Kaspar

    2017-01-01

    This book explores the relations between physical parameters of extrasolar planets and their respective parent stars. Planetary parameters are often directly dependent upon their stellar counterparts. In addition, the star is almost always the only visible component of the system and contains most of the system mass. Consequently, the parent star heavily influences every aspect of planetary physics and astrophysics. Drs. Kaspar von Braun and Tabetha Boyajian use direct methods to characterize exoplanet host starts that minimize the number of assumptions needed to be made in the process. The book provides a background on interferometric techniques for stellar diameter measurements, illustrates the authors' approach on using additional data to fully characterize the stars, provides a comprehensive update on the current state of the field, and examines in detail a number of historically significant and well-studied exoplanetary systems.

  17. Setting the Stage for Habitable Planets

    Directory of Open Access Journals (Sweden)

    Guillermo Gonzalez

    2014-02-01

    Full Text Available Our understanding of the processes that are relevant to the formation and maintenance of habitable planetary systems is advancing at a rapid pace, both from observation and theory. The present review focuses on recent research that bears on this topic and includes discussions of processes occurring in astrophysical, geophysical and climatic contexts, as well as the temporal evolution of planetary habitability. Special attention is given to recent observations of exoplanets and their host stars and the theories proposed to explain the observed trends. Recent theories about the early evolution of the Solar System and how they relate to its habitability are also summarized. Unresolved issues requiring additional research are pointed out, and a framework is provided for estimating the number of habitable planets in the Universe.

  18. CO2 condensation can seriously limit the deglaciation of Earth-like planets

    Science.gov (United States)

    Turbet, M.; Forget, F.; Leconte, J.; Charnay, B.; Tobie, G.

    2017-09-01

    It is widely believed that the carbonate-silicate cycle is the main agent to trigger deglaciations by CO2 greenhouse warming on Earth and by extension on Earth-like planets when they get in frozen state. Using a 3D Global Climate Model, we show that planets with Earth-like characteristics (size, mass, obliquity, rotation rate, ...) orbiting a Sun-like star may never be able to escape from a glaciation era if their orbital distance is greater than ˜1.27 Astronomical Units because CO2 would condense at the poles (here the cold traps) forming permanent CO2 ice caps. This limits the amount of CO2 in the atmosphere and thus its greenhouse effect.

  19. Constraints on Neutral Hydrogen Outflow from the Warm Rocky Planet GJ1132b using Lyman-alpha Transit Observations

    Science.gov (United States)

    Waalkes, William; Berta-Thompson, Zachory; Charbonneau, David; Irwin, Jonathan; Newton, Elisabeth; Dittmann, Jason; Bourrier, Vincent; Ehrenreich, David; Kempton, Eliza

    2018-01-01

    GJ1132b is one of the few known Earth-sized planets, and at 12 pc away it is also one of the closest known transiting planets. With an equilibrium temperature of 500 K, this planet is too hot to be habitable but we can use it to learn about the presence and volatile content of rocky planet atmospheres around M dwarf stars. Using Hubble STIS spectra during primary transit, we explore the potential for UV transit detections of GJ1132b. If we were to observe a deep Lyman-α transit, that would indicate the presence of a neutral hydrogen envelope flowing from GJ1132b. On the other hand, ruling out deep absorption from neutral hydrogen may indicate that this planet has either retained its volatiles or lost them very early in the star’s life. We carry out this analysis by extracting 1D spectra from the STIS pipeline, splitting the time-tagged spectra into higher resolution samples, and producing light curves of the red and blue wings of the Lyman-α line. We fit for the baseline stellar flux and transit depths in order to constrain the characteristics of the cloud of neutral hydrogen gas that may surround the planet. Our work extends beyond the transit study into an analysis of the stellar variability and Lyman-α spectrum of GJ1132, a slowly-rotating 0.18 MSun M dwarf with previously uncharacterized UV activity. Understanding the role that UV variability plays in planetary atmospheres and volatile retention is crucial to assess atmospheric evolution and the habitability of cooler rocky planets.

  20. Planet formation in binary systems: simulating coagulation using analytically determined collision velocities.

    Science.gov (United States)

    Silsbee, Kedron; Rafikov, Roman

    2017-06-01

    The existence of planets in tight binary systems presents an interesting puzzle. It is thought that cores of giant planets form via agglomeration of planetesimals in mutual collisions. However, in tight binary systems, one would naïvely expect the collision velocities between planetesimals to be so high that even 100 km bodies would be destroyed, rather than growing in mutual collisions. In these systems, planetesimals are perturbed by gravity from the companion star, and gravity and gas drag from a massive eccentric gas disk. There is a damaging secular resonance that occurs due to the combination of disk gravity and gravity from the binary companion, however the disk gravity can also create locations of low relative eccentricity between planetesimals of different sizes that would not exist if the disk gravity were ignored. Because the gas drag acts more strongly on smaller planetesimals, orbital eccentricity and apsidal angle depend on planetesimal size. Consequently, planetesimal collision velocities depend on the sizes of the collision partners. Same-size bodies collide at low velocity because their orbits are apsidally aligned. Therefore, often in a given environment some collisions will lead to planetesimal growth, and some to erosion or destruction. This variety of collisional outcomes makes it difficult to determine whether any planetesimals can grow to large sizes. We run a multi-annulus coagulation/fragmentation simulation that also includes the effect of size-dependent radial drift of planetesimals to determine the minimum size of initial planetesimal necessary for growth to large sizes in collisions. The minimum initial size of planetesimal necessary for growth depends greatly on the disk mass, eccentricity and the degree of apsidal alignment with the binary. We find that in a wide variety of situations, it is a reasonable approximation that growth occurs as long as there are no collisions capable of completely destroying a planetesimal, but erosion by

  1. DISCOVERY OF A TRANSITING PLANET NEAR THE SNOW-LINE

    DEFF Research Database (Denmark)

    Kipping, D. M.; Torres, G.; Buchhave, L. A.

    2014-01-01

    In most theories of planet formation, the snow-line represents a boundary between the emergence of the interior rocky planets and the exterior ice giants. The wide separation of the snow-line makes the discovery of transiting worlds challenging, yet transits would allow for detailed subsequent...

  2. Developments in Planet Detection using Transit Timing Variations

    Energy Technology Data Exchange (ETDEWEB)

    Steffen, Jason H.; /Fermilab; Agol, Eric; /Washington U., Seattle, Astron. Dept.

    2006-12-01

    In a transiting planetary system, the presence of a second planet will cause the time interval between transits to vary. These transit timing variations (TTV) are particularly large near mean-motion resonances and can be used to infer the orbital elements of planets with masses that are too small to detect by any other means. The author presents the results of a study of simulated data where they show the potential that this planet detection technique has to detect and characterize secondary planets in transiting systems. These results have important ramifications for planetary transit searches since each transiting system presents an opportunity for additional discoveries through a TTV analysis. They present such an analysis for 13 transits of the HD 209458 system that were observed with the Hubble Space Telescope. This analysis indicates that a putative companion in a low-order, mean-motion resonance can be no larger than the mass of the Earth and constitutes, to date, the most sensitive probe for extrasolar planets that orbit main sequence stars. The presence or absence of small planets in low-order, mean-motion resonances has implications for theories of the formation and evolution of planetary systems. Since TTV is most sensitive in these regimes, it should prove a valuable tool not only for the detection of additional planets in transiting systems, but also as a way to determine the dominant mechanisms of planet formation and the evolution of planetary systems.

  3. Transiting circumbinary planets Kepler-34 b and Kepler-35 b.

    Science.gov (United States)

    Welsh, William F; Orosz, Jerome A; Carter, Joshua A; Fabrycky, Daniel C; Ford, Eric B; Lissauer, Jack J; Prša, Andrej; Quinn, Samuel N; Ragozzine, Darin; Short, Donald R; Torres, Guillermo; Winn, Joshua N; Doyle, Laurance R; Barclay, Thomas; Batalha, Natalie; Bloemen, Steven; Brugamyer, Erik; Buchhave, Lars A; Caldwell, Caroline; Caldwell, Douglas A; Christiansen, Jessie L; Ciardi, David R; Cochran, William D; Endl, Michael; Fortney, Jonathan J; Gautier, Thomas N; Gilliland, Ronald L; Haas, Michael R; Hall, Jennifer R; Holman, Matthew J; Howard, Andrew W; Howell, Steve B; Isaacson, Howard; Jenkins, Jon M; Klaus, Todd C; Latham, David W; Li, Jie; Marcy, Geoffrey W; Mazeh, Tsevi; Quintana, Elisa V; Robertson, Paul; Shporer, Avi; Steffen, Jason H; Windmiller, Gur; Koch, David G; Borucki, William J

    2012-01-11

    Most Sun-like stars in the Galaxy reside in gravitationally bound pairs of stars (binaries). Although long anticipated, the existence of a 'circumbinary planet' orbiting such a pair of normal stars was not definitively established until the discovery of the planet transiting (that is, passing in front of) Kepler-16. Questions remained, however, about the prevalence of circumbinary planets and their range of orbital and physical properties. Here we report two additional transiting circumbinary planets: Kepler-34 (AB)b and Kepler-35 (AB)b, referred to here as Kepler-34 b and Kepler-35 b, respectively. Each is a low-density gas-giant planet on an orbit closely aligned with that of its parent stars. Kepler-34 b orbits two Sun-like stars every 289 days, whereas Kepler-35 b orbits a pair of smaller stars (89% and 81% of the Sun's mass) every 131 days. The planets experience large multi-periodic variations in incident stellar radiation arising from the orbital motion of the stars. The observed rate of circumbinary planets in our sample implies that more than ∼1% of close binary stars have giant planets in nearly coplanar orbits, yielding a Galactic population of at least several million.

  4. SPHERE: A Planet Finder Instrument for the VLT

    NARCIS (Netherlands)

    Beuzit, J.L.; Feldt, M.; Dohlen, K.; Mouillet, D.; Puget, P.; Antichi, J.; Baudoz, P.; Boccaletti, A.; Carbillet, M.; Charton, J.; Claudi, R.; Fusco, T.; Gratton, R.; Henning, T.; Hubin, N.; Joos, F.; Kasper, M.; Langlois, M.; Moutou, C.; Pragt, J.; Rabou, P.; Saisse, M.; Schmid, H.M.; Turatto, M.; Udry, S.; Vakili, F.; Waters, R.; Wildi, F.

    2007-01-01

    Direct detection and spectral characterization of extra-solar planets is one of the most exciting but also one of the most challenging areas in modern astronomy. For its second generation instrumentation on the VLT, ESO has supported two phase A studies for a so-called Planet Finder dedicated

  5. SPHERE: A planet finder instrument for the VLT

    NARCIS (Netherlands)

    Beuzit, J.-L.; Feldt, M.; Dohlen, K.; Mouillet, D.; Puget, P.; Wildi, F.; Abe, L.; Antichi, J.; Baruffolo, A.; Baudoz, P.; Boccaletti, A.; Carbillet, M.; Charton, J.; Claudi, R.; Downing, M.; Fabron, C.; Feautrier, P.; Fedrigo, E.; Fusco, T.; Gach, J.-L.; Gratton, R.; Henning, T.; Hubin, N.; Joos, F.; Kasper, M.; Langlois, M.; Lenzen, R.; Moutou, C.; Pavlov, A.; Petit, C.; Pragt, J.; Rabou, P.; Rigal, F.; Roelfsema, R.; Rousset, G.; Saisse, M.; Schmid, H.-M.; Stadler, E.; Thalmann, C.; Turatto, M.; Udry, S.; Vakili, F.; Waters, R.

    2008-01-01

    Direct detection and spectral characterization of extra-solar planets is one of the most exciting but also one of the most challenging areas in modern astronomy. The challenge consists in the very large contrast between the host star and the planet, larger than 12.5 magnitudes at very small angular

  6. The Solar Twin Planet Search. V. Close-in, low-mass planet candidates and evidence of planet accretion in the solar twin HIP 68468

    Science.gov (United States)

    Meléndez, Jorge; Bedell, Megan; Bean, Jacob L.; Ramírez, Iván; Asplund, Martin; Dreizler, Stefan; Yan, Hong-Liang; Shi, Jian-Rong; Lind, Karin; Ferraz-Mello, Sylvio; Galarza, Jhon Yana; dos Santos, Leonardo; Spina, Lorenzo; Maia, Marcelo Tucci; Alves-Brito, Alan; Monroe, TalaWanda; Casagrande, Luca

    2017-01-01

    Context. More than two thousand exoplanets have been discovered to date. Of these, only a small fraction have been detected around solar twins, which are key stars because we can obtain accurate elemental abundances especially for them, which is crucial for studying the planet-star chemical connection with the highest precision. Aims: We aim to use solar twins to characterise the relationship between planet architecture and stellar chemical composition. Methods: We obtained high-precision (1 m s-1) radial velocities with the HARPS spectrograph on the ESO 3.6 m telescope at La Silla Observatory and determined precise stellar elemental abundances ( 0.01 dex) using spectra obtained with the MIKE spectrograph on the Magellan 6.5 m telescope. Results: Our data indicate the presence of a planet with a minimum mass of 26 ± 4 Earth masses around the solar twin HIP 68468. The planet is more massive than Neptune (17 Earth masses), but unlike the distant Neptune in our solar system (30 AU), HIP 68468c is close-in, with a semi-major axis of 0.66 AU, similar to that of Venus. The data also suggest the presence of a super-Earth with a minimum mass of 2.9 ± 0.8 Earth masses at 0.03 AU; if the planet is confirmed, it will be the fifth least massive radial velocity planet candidate discovery to date and the first super-Earth around a solar twin. Both isochrones (5.9 ± 0.4 Gyr) and the abundance ratio [Y/Mg] (6.4 ± 0.8 Gyr) indicate an age of about 6 billion years. The star is enhanced in refractory elements when compared to the Sun, and the refractory enrichment is even stronger after corrections for Galactic chemical evolution. We determined a nonlocal thermodynamic equilibrium Li abundance of 1.52 ± 0.03 dex, which is four times higher than what would be expected for the age of HIP 68468. The older age is also supported by the low log () (-5.05) and low jitter (lithium and the refractory elements. Conclusions: The super-Neptune planet candidate is too massive for in situ

  7. How to Pluck a Spectrum from a Planet

    Science.gov (United States)

    2007-01-01

    This diagram illustrates how astronomers using NASA's Spitzer Space Telescope can capture the elusive spectra of hot-Jupiter planets. Spectra are an object's light spread apart into its basic components, or wavelengths. By dissecting light in this way, scientists can sort through it and uncover clues about the composition of the object giving off the light. To obtain a spectrum for an object, one first needs to capture its light. Hot-Jupiter planets are so close to their stars that even the most powerful telescopes can't distinguish their light from the light of their much brighter stars. But, there are a few planetary systems that allow astronomers to measure the light from just the planet by using a clever technique. Such 'transiting' systems are oriented in such a way that, from our vantage point, the planets' orbits are seen edge-on and cross directly in front of and behind their stars. In this technique, known as the secondary eclipse method, changes in the total infrared light from a star system are measured as its planet transits behind the star, vanishing from our Earthly point of view. The dip in observed light can then be attributed to the planet alone. To capture a spectrum of the planet, Spitzer must observe the system twice. It takes a spectrum of the star together with the planet (first panel), then, as the planet disappears from view, a spectrum of just the star (second panel). By subtracting the star's spectrum from the combined spectrum of the star plus the planet, it is able to get the spectrum for just the planet (third panel). This ground-breaking technique was used by Spitzer to obtain the first-ever spectra of two planets beyond our solar system, HD 209458b and HD 189733b. The results suggest that the hot planets are socked in with dry clouds high up in the planet's stratospheres. In addition, HD 209458b showed hints of silicates, indicating those high clouds might be made of very fine sand-like particles.

  8. Remote sensing of planetary properties and biosignatures on extrasolar terrestrial planets.

    Science.gov (United States)

    Des Marais, David J; Harwit, Martin O; Jucks, Kenneth W; Kasting, James F; Lin, Douglas N C; Lunine, Jonathan I; Schneider, Jean; Seager, Sara; Traub, Wesley A; Woolf, Neville J

    2002-01-01

    The major goals of NASA's Terrestrial Planet Finder (TPF) and the European Space Agency's Darwin missions are to detect terrestrial-sized extrasolar planets directly and to seek spectroscopic evidence of habitable conditions and life. Here we recommend wavelength ranges and spectral features for these missions. We assess known spectroscopic molecular band features of Earth, Venus, and Mars in the context of putative extrasolar analogs. The preferred wavelength ranges are 7-25 microns in the mid-IR and 0.5 to approximately 1.1 microns in the visible to near-IR. Detection of O2 or its photolytic product O3 merits highest priority. Liquid H2O is not a bioindicator, but it is considered essential to life. Substantial CO2 indicates an atmosphere and oxidation state typical of a terrestrial planet. Abundant CH4 might require a biological source, yet abundant CH4 also can arise from a crust and upper mantle more reduced than that of Earth. The range of characteristics of extrasolar rocky planets might far exceed that of the Solar System. Planetary size and mass are very important indicators of habitability and can be estimated in the mid-IR and potentially also in the visible to near-IR. Additional spectroscopic features merit study, for example, features created by other biosignature compounds in the atmosphere or on the surface and features due to Rayleigh scattering. In summary, we find that both the mid-IR and the visible to near-IR wavelength ranges offer valuable information regarding biosignatures and planetary properties; therefore both merit serious scientific consideration for TPF and Darwin.

  9. The Longevity of Water Ice on Ganymedes and Europas around Migrated Giant Planets

    Energy Technology Data Exchange (ETDEWEB)

    Lehmer, Owen R.; Catling, David C. [Dept. of Earth and Space Sciences/Astrobiology Program, University of Washington, Seattle, WA (United States); Zahnle, Kevin J., E-mail: olehmer@gmail.com [NASA Ames Research Center, Moffett Field, CA (United States)

    2017-04-10

    The gas giant planets in the Solar System have a retinue of icy moons, and we expect giant exoplanets to have similar satellite systems. If a Jupiter-like planet were to migrate toward its parent star the icy moons orbiting it would evaporate, creating atmospheres and possible habitable surface oceans. Here, we examine how long the surface ice and possible oceans would last before being hydrodynamically lost to space. The hydrodynamic loss rate from the moons is determined, in large part, by the stellar flux available for absorption, which increases as the giant planet and icy moons migrate closer to the star. At some planet–star distance the stellar flux incident on the icy moons becomes so great that they enter a runaway greenhouse state. This runaway greenhouse state rapidly transfers all available surface water to the atmosphere as vapor, where it is easily lost from the small moons. However, for icy moons of Ganymede’s size around a Sun-like star we found that surface water (either ice or liquid) can persist indefinitely outside the runaway greenhouse orbital distance. In contrast, the surface water on smaller moons of Europa’s size will only persist on timescales greater than 1 Gyr at distances ranging 1.49–0.74 au around a Sun-like star for Bond albedos of 0.2 and 0.8, where the lower albedo becomes relevant if ice melts. Consequently, small moons can lose their icy shells, which would create a torus of H atoms around their host planet that might be detectable in future observations.

  10. Directly Imaged Giant Planets: What Do We Hope to Learn?

    Science.gov (United States)

    Marley, Mark

    2015-01-01

    As we move into an era when GPI and SPHERE are (hopefully) discovering and characterizing new young giant planets, it is worthwhile to step back and review our science goals for young giant planets. Of course for individual planets we ideally would hope to measure mass, radius, atmospheric composition, temperature, and cloud properties, but how do these characteristics fit into our broader understanding of planetary system origin and evolution theories? In my presentation I will review both the specifics of what we hope to learn from newly discovered young worlds as well as how these characteristics inform our broader understanding of giant planets and planetary systems. Finally I will consider the limitations realistic datasets will place on our ability to understand newly discovered planets, illustrating with data from any new such worlds that are available by the conference date.

  11. A Direct Path to Finding Earth-Like Planets

    Science.gov (United States)

    Heap, Sara R.; Linder, Don J.

    2009-01-01

    As envisaged by the 2000 astrophysics decadal survey panel: The main goal of Terrestrial Planet Finder (TPF) is nothing less than to search for evidence of life on terrestrial planets around nearby stars . Here, we consider how an optical telescope paired with a free-flying occulter blocking light from the star can reach this goal directly, without knowledge of results from prior astrometric, doppler, or transit exoplanet observations. Using design reference missions and other simulations, we explore the potential of TPF-O to find planets in the habitable zone around their central stars, to spectrally characterize the atmospheres of detected planets, and to obtain rudimentary information about their orbits. We emphasize the importance of ozone absorption in the UV spectrum of a planet as a marker of photosynthesis by plants, algae, and cyanobacteria.

  12. Planet destruction and the shaping of planetary nebulae

    Science.gov (United States)

    Boyle, L. A.; Redman, M. P.

    2017-10-01

    The shaping of PNe as a result of an interaction with a planet is a hypothesis that has been suggested for nearly two decades. However, exploring the idea observationally is challenging due to the lack of capabilities needed to detect any evidence of such a scenario. Nonetheless, we propose that the hypothesis can be indirectly tested via a combination of exoplanet formation and evolution theories, the star and planet formation histories of the galaxy and the tidal evolution of star-planet systems. We present a calculation of the fraction of planetary nebulae in the galaxy today which have undergone an interaction with a planet, concluding that a significant number of visible planetary nebulae may have been shaped by a planet.

  13. Direct imaging of multiple planets orbiting the star HR 8799

    Energy Technology Data Exchange (ETDEWEB)

    Marois, C; Macintosh, B; Barman, T; Zuckerman, B; Song, I; Patience, J; Lafreniere, D; Doyon, R

    2008-10-14

    Direct imaging of exoplanetary systems is a powerful technique that can reveal Jupiter-like planets in wide orbits, can enable detailed characterization of planetary atmospheres, and is a key step towards imaging Earth-like planets. Imaging detections are challenging due to the combined effect of small angular separation and large luminosity contrast between a planet and its host star. High-contrast observations with the Keck and Gemini telescopes have revealed three planets orbiting the star HR 8799, with projected separations of 24, 38, and 68 astronomical units. Multi-epoch data show counter-clockwise orbital motion for all three imaged planets. The low luminosity of the companions and the estimated age of the system imply planetary masses between 5 and 13 times that of Jupiter. This system resembles a scaled-up version of the outer portion of our Solar System.

  14. Planet population synthesis driven by pebble accretion in cluster environments

    Science.gov (United States)

    Ndugu, N.; Bitsch, B.; Jurua, E.

    2018-02-01

    The evolution of protoplanetary discs embedded in stellar clusters depends on the age and the stellar density in which they are embedded. Stellar clusters of young age and high stellar surface density destroy protoplanetary discs by external photoevaporation and stellar encounters. Here, we consider the effect of background heating from newly formed stellar clusters on the structure of protoplanetary discs and how it affects the formation of planets in these discs. Our planet formation model is built on the core accretion scenario, where we take the reduction of the core growth time-scale due to pebble accretion into account. We synthesize planet populations that we compare to observations obtained by radial velocity measurements. The giant planets in our simulations migrate over large distances due to the fast type-II migration regime induced by a high disc viscosity (α = 5.4 × 10-3). Cold Jupiters (rp > 1 au) originate preferably from the outer disc, due to the large-scale planetary migration, while hot Jupiters (rp population of isolated stars host a significant amount of giant planets even at low metallicity, in contradiction to observations where giant planets are preferably found around high metallicity stars, indicating that pebble accretion is very efficient in the standard pebble accretion framework. On the other hand, discs around stars embedded in cluster environments hardly form any giant planets at low metallicity in agreement with observations, where these changes originate from the increased temperature in the outer parts of the disc, which prolongs the core accretion time-scale of the planet. We therefore conclude that the outer disc structure and the planet's formation location determines the giant planet occurrence rate and the formation efficiency of cold and hot Jupiters.

  15. Electromagnetic heating of minor planets in the early solar system

    Science.gov (United States)

    Herbert, F.; Sonett, C. P.

    1979-01-01

    Electromagnetic processes occurring in the primordial solar system are likely to have significantly affected planetary evolution. In particular, electrical coupling of the kinetic energy of a dense T-Tauri-like solar wind into the interior of the smaller planets could have been a major driver of thermal metamorphism. Accordingly a grid of asteroid models of various sizes and solar distances was constructed using dc transverse magnetic induction theory. Plausible parameterizations with no requirement for a high environmental temperature led to complete melting for Vesta with no melting for Pallas and Ceres. High temperatures were reached in the Pallas model, perhaps implying nonmelting thermal metamorphosis as a cause of its anomalous spectrum. A reversal of this temperature sequence seems implausible, suggesting that the Ceres-Pallas-Vesta dichotomy is a natural outcome of the induction mechanism. Highly localized heating is expected to arise due to an instability in the temperature-controlled current distribution. Localized metamorphosis resulting from this effect may be relevant to the production and evolution of pallasites, the large presumed metal component of S object spectra, and the formation of the lunar magma ocean.

  16. Terraforming planet Dune: Climate-vegetation interactions on a sandy planet

    Science.gov (United States)

    Cresto Aleina, F.; Baudena, M.; D'Andrea, F.; Provenzale, A.

    2012-04-01

    The climate and the biosphere of planet Earth interact in multiple, complicated ways and on many spatial and temporal scales. Some of these processes can be studied with the help of simple mathematical models, as done for the effects of vegetation on albedo in desert areas and for the mechanisms by which terrestrial vegetation affects water fluxes in arid environments. Conceptual models of this kind do not attempt at providing quantitative descriptions of the climate-biosphere interaction, but rather to explore avenues and mechanisms which can play a role in the real system, providing inspiration for further research. In this work, we develop a simple conceptual box model in the spirit illustrated above, to explore whether and how vegetation affects the planetary hydrologic cycle. We imagine a planet with no oceans and whose surface is entirely covered with sand, quite similar to planet Dune of the science-fiction series by Frank Herbert (1965). We suppose that water is entirely in the sand, below the surface. Without vegetation, only evaporation takes place, affecting the upper sand layer for a maximum depth of a few cm. The amount of water that is evaporated in the atmosphere is relatively small, and not sufficient to trigger a full hydrologic cycle. The question is what happens to this planet when vegetation is introduced: the root depth can reach a meter or more, and plant transpiration can then transfer a much larger amount of water to the atmosphere. One may wonder whether the presence of vegetation is sufficient to trigger a hydrologic cycle with enough precipitation to sustain the vegetation itself and, if the answer is positive, what is the minimum vegetation cover that is required to maintain the cycle active. In more precise terms, we want to know whether the introduction of vegetation and of the evapotranspiration feedback allows for the existence of multiple equilibria (or solutions) in the soil-vegetation-atmosphere system. Although the box model

  17. ADONIS Discovers Dust Disk around a Star with a Planet

    Science.gov (United States)

    2000-10-01

    from the Voyager spacecraft have shown that this dust extends quite far out, well beyond the orbit of planet Pluto. Observations of stellar disks with ADONIS The team used the ADONIS instrument with the SHARP II camera to search for dust disks around the iota Horologii planetary system. ADONIS corrects the atmospheric turbulence in real-time by means of a computer-controlled flexible mirror, allowing the sharpest possible images to be recorded with this special camera. In order to detect circumstellar material, it is an absolute condition that the light that is recorded from the star itself is reduced to a minimum. The circumstellar dust reflects only a small fraction of the stellar light and would otherwise be completely outshone by the intense light from the star in the middle. This is achieved by inserting in front of the detector a so-called coronographic mask that blocks the light of the star. The chosen diameter is a compromise between the desire to detect features as close as possible to the star and the rapidly increasing amount of stellar light as the size of the mask is decreased. For the the present observations of iota Horologii , a mask with a diameter of 1.0 arcsec was used (about 17 AU, or 2550 million km at the distance of the star). A series of short exposures were made through a near-infrared filter (in the H-band that is centred at wavelength 1.64 µm), a spectral region where the disk/star light intensity ratio and the instrument efficiency are optimal. In the course of the extensive data analysis the exposures are combined to produce the resulting image of the star. Moreover, to correct for stray light in the instrument, it is necessary to "subtract" the image of a reference star which is known to be free of any circumstellar material. This procedure effectively reduces the unavoidable halo of instrumentally introduced stray light from the star that - despite the mask - is still significantly brighter than the light coming from the disk. The dust

  18. Planet hunters. VI. An independent characterization of KOI-351 and several long period planet candidates from the Kepler archival data

    Energy Technology Data Exchange (ETDEWEB)

    Schmitt, Joseph R.; Wang, Ji; Fischer, Debra A.; Moriarty, John C.; Boyajian, Tabetha S. [Department of Astronomy, Yale University, New Haven, CT 06511 (United States); Jek, Kian J.; LaCourse, Daryll; Omohundro, Mark R.; Winarski, Troy; Goodman, Samuel Jon; Jebson, Tony; Schwengeler, Hans Martin; Paterson, David A.; Schwamb, Megan E. [Institute of Astronomy and Astrophysics, Academia Sinica, 11F of Astronomy-Mathematics Building, National Taiwan University. No.1, Sec. 4, Roosevelt Rd, Taipei 10617, Taiwan (China); Lintott, Chris; Simpson, Robert [Oxford Astrophysics, Denys Wilkinson Building, Keble Road, Oxford OX1 3RH (United Kingdom); Lynn, Stuart; Smith, Arfon M.; Parrish, Michael [Adler Planetarium, 1300 S. Lake Shore Drive, Chicago, IL 60605 (United States); Schawinski, Kevin, E-mail: joseph.schmitt@yale.edu [Institute for Astronomy, Department of Physics, ETH Zurich, Wolfgang-Pauli-Strasse 16, CH-8093 Zurich (Switzerland); and others

    2014-08-01

    We report the discovery of 14 new transiting planet candidates in the Kepler field from the Planet Hunters citizen science program. None of these candidates overlapped with Kepler Objects of Interest (KOIs) at the time of submission. We report the discovery of one more addition to the six planet candidate system around KOI-351, making it the only seven planet candidate system from Kepler. Additionally, KOI-351 bears some resemblance to our own solar system, with the inner five planets ranging from Earth to mini-Neptune radii and the outer planets being gas giants; however, this system is very compact, with all seven planet candidates orbiting ≲ 1 AU from their host star. A Hill stability test and an orbital integration of the system shows that the system is stable. Furthermore, we significantly add to the population of long period transiting planets; periods range from 124 to 904 days, eight of them more than one Earth year long. Seven of these 14 candidates reside in their host star's habitable zone.

  19. Mars: A water-rich planet?

    Science.gov (United States)

    Carr, M.H.

    1986-01-01

    Mars had outgassed at least 0.5 to 1 km of water, 10 to 20 bar of CO2, and 0.1 to 0.3 bar of N2. The volatiles that have been retained are mostly in the cratered uplands. Terrain softening, fretted channels, debris flows, and closed depressions indicate that at least the upper 2 km of the cratered uplands at high latitudes (>30??) contain ice in amounts that exceed the porosity, estimated to be 10-20%. Theoretical studies, and lack of these features in the cratered uplands at low latitudes, suggest that the upper 1 km of the uplands at low latitudes is ice poor. However, valley networks indicate that water was present near the surface early in the planet's history, although in amounts smaller than at high latitudes. The entire upper 1 km, planetwide is estimated to have contained 75-125 m of water at the end of heavy bombardment. The largest sink for water is the megaregolith below 1 km. Episodic eruption of water from the deep megaregolith cut many of the large outflow channels. From the volume of water needed to cut the circum-Chryse channels, and assuming uniform planetwide distribution of water, the deep megaregolith is estimated to have contained at least 350 m of water at the end of heavy bombardment, thereby giving a total minimum inventory of 424-475 m planetwide. Most of the water lost from the low-latitude uplands by diffusion and in cutting the valley networks is now believed to be in the polar layered terrains. Most of the water involved in cutting the outflow channels is in the low-lying northern plains where a variety of features that have been attributed to ground ice is present. A large fraction of the planet's surface has been overplated with water-poor volcanics, of which we have samples in the SNC meteorites. The younger volcanics have reacted extensively with the old volatile-rich basement. Some of the CO2 and N2 outgassed was lost during heavy bombardment by impact erosion of the atmosphere and other processes. The remaining was fixed

  20. Students learn how to cool the planet

    Science.gov (United States)

    Santos, Anabela

    2013-04-01

    I teach students aged 13/14 years in the eighth grade. In the natural sciences we study aspects of the greenhouse effect and global warming. At the time I was reading the book "Como Arrefecer o Planeta" (How to cool the planet) by Professor João Lin Yun, a scientist and researcher at the University of Lisbon. I thought the book explicitly clarified this issue and would be very accessible to my students. I had an idea of teaching this academic content differently than usual. Therefore I suggested that the students read this book, which they did without exception. As I noticed that the students had a great interest in the book, I thought to invite the author to visit our school and spend a day with us. Professor Lin Yun readily accepted the invitation. In the classroom, the students prepared the contents of the book in order to discuss the subjects with the book's author and question the author about their doubts and the clarifications they needed. They also created a PowerPoint where they conveyed their interpretation of the book. Professor Lin Yun spent a day with students, where there were moments of debate and didactic-ludic work. It was a very fascinating and enriching experience because students learn differently, outside the classroom and in the presence of the author of the book they have read. They were also prepared for the assessment test and were more sensitive to the issue of climate change and other environmental changes. In response to some questions - It was humans, each of us with our carbon footprint, we have created this problem. So if we had the ability to create the problem, we also have the ability to solve it? - Our individual contribution is important and meaningful? They concluded that in view of the current changes, we must change attitudes, to overcome these new challenges. The models of behavior and thoughts inherited from our ancestors must be replaced by modern solutions and decision-making regarding the future. Albert Einstein said

  1. Evaluation of Preservation Planning within OAIS, based on the Planets Functional Model

    OpenAIRE

    Sierman, Barbara; Wheatley, Paul

    2010-01-01

    This report gives an overview of the Planets Functional Model and relates it to the Planets deliverables. It also gives a set of recommendations for the OAIS model. The Report was part of the European FP6 Project Planets

  2. Worlds beyond our own the search for habitable planets

    CERN Document Server

    Sengupta, Sujan

    2015-01-01

    This is a book on planets: Solar system planets and dwarf planets. And planets outside our solar system – exoplanets. How did they form? What types of planets are there and what do they have in common? How do they differ? What do we know about their atmospheres – if they have one? What are the conditions for life and on which planets may they be met? And what’s the origin of life on Earth and how did it form? You will understand how rare the solar system, the Earth and hence life is. This is also a book on stars. The first and second generation of stars in the Universe. But in particular also on the link between planets and stars – brown dwarfs. Their atmospheric properties and similarities with giant exoplanets. All these fascinating questions will be answered in a non-technical manner. But those of you who want to know a bit more may look up the relevant mathematical relationships in appendices.

  3. Literature in Focus : Playing with Planets

    CERN Multimedia

    2009-01-01

    If you think the future is a mystery, think again. With a solid foothold in realism, an extraordinary insight into scientific and technological developments, and a dry sense of humor, Nobel laureate Professor Gerardus ’t Hoof confidently dissects fact from fiction and shows us what our future might really hold. Professor ’t Hooft takes the reader firmly by the hand and, within the boundaries of solid physics and proven laws of nature, takes us on a ride into the world of the future, which holds remarkable surprises for us all. "Do you dream of intergalaxy space travel, time warps and mini-mes? t’Hooft asks. "Then please get yourself some more science fiction books, for fiction that is. But for those who are interested in the real world, let me tell you what we CAN expect for the future." Gerardus t’Hooft Playing with Planets World Scientific Publishing, 17 March 2008, 3pm In the Library, Bldg 52-1-052 Tea and coffee will be served

  4. We too may find new planets

    Science.gov (United States)

    Diaz-Merced, Wanda Liz Liz

    2017-05-01

    Significant Scintillation of Radio Waves is caused by Plasma Instabilities. Radio Frequency radiation is emitted by a large amount extra-terrestrial sources. These radio waves contains information about these objects through the large portion of the electromagnetic spectra. Propagation of electromagnetic waves, like optical or radio waves, through a medium with random fluctuations in Refractive Index results in amplitude and phase fluctuations. In this poster we will present an amateur project exploring the possible different mechanisms of the influence of a central star or solar activity on a possible planet (e.g magnetospheric, atmospheric etc) parameters( Perez-Peraza et.al 2007). Examples of sonified spectral analysis techniques , (using earth and our sun as a probe) for the amateur astronomer are demonstrated following strict accessibility guidelines. Sunspot and magnetometer data (interplanetary magnetic field (ACE satellite) and geomagnetic field (GOES satellite)) as well as decametric antenna signals are analyzed in context of the Sun-Earth connection. Those are compared with the predictions of theoretical models of the influence of Solar activity on a possible atmosphere (Perez-Peraza et.al 2007): our amateur results and methodologies confirm the relationship between the variations of geomagnetic/atmospheric parameters and variations of galactic and solar cosmic rays modelled by Perez-Peraza et.al 2007.

  5. Surviving Armageddon - Solutions for a Threatened Planet

    Science.gov (United States)

    McGuire, Bill

    2005-07-01

    What do earthquakes, magma, asteroid 1950DA, and global warming have in common? All are very real natural disasters, already under way; all are also the focus of intensive work by scientists, aimed at preventing, predicting, or at least limiting their impact on civilization. Using the latest chilling data and taking care to draw a clear line between scientific fact and fiction, McGuire discusses the various ways that scientists have already started to prepare for survival. Solutions on earth range from 'space reflectors' to prevent global warming, to pressure-relieving 'robot excavators' to stop volcanic eruptions. In space, NASA is developing rocket motors to gently nudge asteroids out of Earth's path, and plans to have all threatening asteroids larger than 1km detected by 2008, thereby enabling us to predict possible collisions up to 2880. The book provides the strategies to the problems we face, and concludes optimistically with ways in which we can use technology to protect our society and planet from global catastrophe.

  6. The Earth is a Planet Too!

    Science.gov (United States)

    Cairns, Brian

    2014-01-01

    When the solar system formed, the sun was 30 dimmer than today and Venus had an ocean. As the sun brightened, a runaway greenhouse effect caused the Venus ocean to boil away. At times when Earth was younger, the sun less bright, and atmospheric CO2 less, Earth froze over (snowball Earth). Earth is in the sweet spot today. Venus is closer to sun than Earth is, but cloud-covered Venus absorbs only 25 of incident sunlight, while Earth absorbs 70. Venus is warmer because it has a thick carbon dioxide atmosphere causing a greenhouse effect of several hundred degrees. Earth is Goldilocks choice among the planets, the one that is just right for life to exist. Not too hot. Not too cold. How does the Earth manage to stay in this habitable range? Is there a Gaia phenomenon keeping the climate in bounds? A nice idea, but it doesnt work. Today, greenhouse gas levels are unprecedented compared to the last 450,000 years.

  7. Accounting for planet-shaped planetary nebulae

    Science.gov (United States)

    Sabach, Efrat; Soker, Noam

    2018-01-01

    By following the evolution of several observed exoplanetary systems, we show that by lowering the mass-loss rate of single solar-like stars during their two giant branches, these stars will swallow their planets at the tip of their asymptotic giant branch (AGB) phase. This will most likely lead the stars to form elliptical planetary nebulae (PNe). Under the traditional mass-loss rate these stars will hardly form observable PNe. Stars with a lower mass-loss rate as we propose, about 15 per cent of the traditional mass-loss rate of single stars, leave the AGB with much higher luminosities than what traditional evolution produces. Hence, the assumed lower mass-loss rate might also account for the presence of bright PNe in old stellar populations. We present the evolution of four exoplanetary systems that represent stellar masses in the range of 0.9-1.3 M⊙. The justification for this low mass-loss rate is our assumption that the stellar samples that were used to derive the traditional average single-star mass-loss rate were contaminated by stars that suffer binary interaction.

  8. A brand new science for the planet

    CERN Multimedia

    CERN Bulletin

    2010-01-01

    “When the problem gets complicated, networking is the solution”. This is nothing new in principle but what Bob Bishop has in mind is one of those novelties that have the potential to change the course of history. He proposes to start networking sciences to create new knowledge. All this for the benefit – and the survival – of the planet.   At the end of the fifteenth and the start of the sixteenth centuries, Leonardo da Vinci was not only an engineer but also a painter, a mathematician and an architect. But in more recent years the sciences have evolved more towards specialization. “We have been treating the sciences as separate stovepipes and silos for over 200 years”, says Bob Bishop, former CEO at Silicon Graphics and a physicist with more than 40 years’ experience in scientific, technical and engineering computing. On 29 January, Bob Bishop visited CERN and gave a seminar on the role of computing in climate science. He is ...

  9. Tandem planet formation for solar system-like planetary systems

    Directory of Open Access Journals (Sweden)

    Yusuke Imaeda

    2017-03-01

    Full Text Available We present a new united theory of planet formation, which includes magneto-rotational instability (MRI and porous aggregation of solid particles in a consistent way. We show that the “tandem planet formation” regime is likely to result in solar system-like planetary systems. In the tandem planet formation regime, planetesimals form at two distinct sites: the outer and inner edges of the MRI suppressed region. The former is likely to be the source of the outer gas giants, and the latter is the source for the inner volatile-free rocky planets. Our study spans disks with a various range of accretion rates, and we find that tandem planet formation can occur for M˙=10−7.3-10−6.9M⊙yr−1. The rocky planets form between 0.4–2 AU, while the icy planets form between 6–30 AU; no planets form in 2–6 AU region for any accretion rate. This is consistent with the gap in the solid component distribution in the solar system, which has only a relatively small Mars and a very small amount of material in the main asteroid belt from 2–6 AU. The tandem regime is consistent with the idea that the Earth was initially formed as a completely volatile-free planet. Water and other volatile elements came later through the accretion of icy material by occasional inward scattering from the outer regions. Reactions between reductive minerals, such as schreibersite (Fe3P, and water are essential to supply energy and nutrients for primitive life on Earth.

  10. Detecting tree-like multicellular life on extrasolar planets.

    Science.gov (United States)

    Doughty, Christopher E; Wolf, Adam

    2010-11-01

    Over the next two decades, NASA and ESA are planning a series of space-based observatories to find Earth-like planets and determine whether life exists on these planets. Previous studies have assessed the likelihood of detecting life through signs of biogenic gases in the atmosphere or a red edge. Biogenic gases and the red edge could be signs of either single-celled or multicellular life. In this study, we propose a technique with which to determine whether tree-like multicellular life exists on extrasolar planets. For multicellular photosynthetic organisms on Earth, competition for light and the need to transport water and nutrients has led to a tree-like body plan characterized by hierarchical branching networks. This design results in a distinct bidirectional reflectance distribution function (BRDF) that causes differing reflectance at different sun/view geometries. BRDF arises from the changing visibility of the shadows cast by objects, and the presence of tree-like structures is clearly distinguishable from flat ground with the same reflectance spectrum. We examined whether the BRDF could detect the existence of tree-like structures on an extrasolar planet by using changes in planetary albedo as a planet orbits its star. We used a semi-empirical BRDF model to simulate vegetation reflectance at different planetary phase angles and both simulated and real cloud cover to calculate disk and rotation-averaged planetary albedo for a vegetated and non-vegetated planet with abundant liquid water. We found that even if the entire planetary albedo were rendered to a single pixel, the rate of increase of albedo as a planet approaches full illumination would be comparatively greater on a vegetated planet than on a non-vegetated planet. Depending on how accurately planetary cloud cover can be resolved and the capabilities of the coronagraph to resolve exoplanets, this technique could theoretically detect tree-like multicellular life on exoplanets in 50 stellar systems.

  11. Size matter!

    DEFF Research Database (Denmark)

    Hansen, Pelle Guldborg; Jespersen, Andreas Maaløe; Skov, Laurits Rhoden

    2015-01-01

    trash bags according to size of plates and weighed in bulk. Results Those eating from smaller plates (n=145) left significantly less food to waste (aver. 14,8g) than participants eating from standard plates (n=75) (aver. 20g) amounting to a reduction of 25,8%. Conclusions Our field experiment tests...

  12. Young Stars Poised for Production of Rocky Planets

    Science.gov (United States)

    2004-11-01

    "signatures" of crystalline pyroxene and olivine, i.e. peaks at wavelength 9.2 and 11.3 µm, respectively, are clearly visible in the spectrum of the inner stellar disc, demonstrating the presence of these species in that region of the disc. The Sun was born about 4,500 million years ago from a cold and massive cloud of interstellar gas and dust that collapsed under its own gravitational pull. A dusty disc was present around the young star, in which the Earth and other planets, as well as comets and asteroids were later formed. This epoch is long gone, but we may still witness that same process by observing the infrared emission from very young stars and the dusty protoplanetary discs around them. So far, however, the available instrumentation did not allow a study of the distribution of the different components of the dust in such discs; even the closest known are too far away for the best single telescopes to resolve them. But now, as Francesco Paresce, Project Scientist for the VLT Interferometer and a member of the team from ESO explains, "With the VLTI we can combine the light from two well-separated large telescopes to obtain unprecedented angular resolution. This has allowed us, for the first time, to peer directly into the innermost region of the discs around some nearby young stars, right in the place where we expect planets like our Earth are forming or will soon form". Specifically, new interferometric observations of three young stars by an international team [2], using the combined power of two 8.2-m VLT telescopes a hundred metres apart, has achieved sufficient image sharpness (about 0.02 arcsec) to measure the infrared emission from the inner region of the discs around three stars (corresponding approximately to the size of the Earth's orbit around the Sun) and the emission from the outer part of those discs. The corresponding infrared spectra have provided crucial information about the chemical composition of the dust in the discs and also about the average

  13. The Gemini Planet Imager: From Science to Design to Construction

    Energy Technology Data Exchange (ETDEWEB)

    Macintosh, B; Graham, J R; Palmer, D; Doyon, R; Dunn, J; Gavel, D; Larkin, J; Oppenheimer, B; Saddlemyer, L; Sivaramakrishnan, A; Wallace, J K; Bauman, B; Erickson, D; Marois, C; Poyneer, L; Soummer, R

    2008-07-01

    The Gemini Planet Imager (GPI) is a facility instrument under construction for the 8-m Gemini South telescope. It combines a 1500 subaperture AO system using a MEMS deformable mirror, an apodized-pupil Lyot coronagraph, a high-accuracy IR interferometer calibration system, and a near-infrared integral field spectrograph to allow detection and characterization of self-luminous extrasolar planets at planet/star contrast ratios of 10{sup -7}. I will discuss the evolution from science requirements through modeling to the final detailed design, provide an overview of the subsystems and show models of the instrument's predicted performance.

  14. Water in Extrasolar Planets and Implications for Habitability

    Science.gov (United States)

    Noack, Lena; Snellen, Ignas; Rauer, Heike

    2017-10-01

    Exoplanet detection missions have found thousands of planets or planet candidates outside of the Solar System—some of which are in the habitable zone, where liquid water is possible at the surface. We give an overview of the recent progress in observations of water-rich exoplanets, detection of water in the atmosphere of gas giants and less-massive targets, and modelling of the interior and evolution of water layers in exoplanets. We summarise the possible habitability of water-rich planets and discuss the potential of future missions and telescopes towards the detection of water in the atmosphere of low-mass exoplanets or on their surface.

  15. Design and Performance of the Terrestrial Planet Finder Coronagraph

    Science.gov (United States)

    White, Mary L.; Shaklan, Stuart; Lisman, P. Doulas; Ho, Timothy; Mouroulis, Pantazis; Basinger, Scott; Ledeboer, Bill; Kwack, Eug; Kissil, Andy; Mosier, Gary; hide

    2004-01-01

    Terrestrial Planet Finder Coronagraph, one of two potential architectures, is described. The telescope is designed to make a visible wavelength survey of the habitable zones of at least thirty stars in search of earth-like planets. The preliminary system requirements, optical parameters, mechanical and thermal design, operations scenario and predicted performance is presented. The 6-meter aperture telescope has a monolithic primary mirror, which along with the secondary tower, are being designed to meet the stringent optical tolerances of the planet-finding mission. Performance predictions include dynamic and thermal finite element analysis of the telescope optics and structure, which are used to make predictions of the optical performance of the system.

  16. IAU Planet Definition: Some Confusions and Their Modifications

    OpenAIRE

    Sarma, R.; Baruah, K.; Sarma, J. K.

    2008-01-01

    International Astronomical Union (IAU) has passed the must needed definition of planet in its general assembly held in Prague during August 2006. The definition had to be passed by means of voting. A group of scientists who raised the banner of revolt against the IAU definition has pointed out that the IAU has failed to give an acceptable definition regarding a planet. A brief description of the serious objections found in the definition of planet has been discussed here. In this paper an att...

  17. Directly Imaging Planets with SCExAO: First Results

    Science.gov (United States)

    Currie, Thayne M.; Guyon, Olivier; Jovanovic, Nemanja; Lozi, Julien; Tamura, Motohide; Kudo, Tomoyuki; Uyama, Taichi; Garcia, Eugenio

    2017-01-01

    We present the first science results from the newly commissioned Subaru Coronagraphic Extreme Adaptive Optics project, an experimental system dedicated to image faint jovian planets around nearby stars. SCExAO is now achieving true extreme AO capability. We describe the typical performance of SCExAO, the first images of benchmark exoplanets and planet-forming disks, and SCExAO’s first science results. Finally, we briefly chart the path forward for SCExAO to achieve its full scientific capability, including imaging mature planets in reflected light.

  18. High-resolution imaging of Kepler planet host candidates. A comprehensive comparison of different techniques

    Science.gov (United States)

    Lillo-Box, J.; Barrado, D.; Bouy, H.

    2014-06-01

    Context. The Kepler mission has discovered thousands of planet candidates. Currently, some of them have already been discarded; more than 200 have been confirmed by follow-up observations (most by radial velocity and few by other methods), and several hundreds have been validated. However, the large majority of the candidates are still awaiting for confirmation. Thus, priorities (in terms of the probability of the candidate being a real planet) must be established for subsequent radial velocity observations. Aims: The motivation of this work is to provide a set of isolated (good) host candidates to be further tested by other techniques that allow confirmation of the planet. As a complementary goal, we aim to identify close companions of the candidates that could have contaminated the light curve of the planet host due to the large pixel size of the Kepler CCD and its typical PSF of around 6 arcsec. Both goals can also provide robust statistics about the multiplicity of the Kepler hosts. Methods: We used the AstraLux North instrument located at the 2.2 m telescope in the Calar Alto Observatory (Almería, Spain) to obtain diffraction-limited images of 174 Kepler objects of interest. A sample of demoted Kepler objects of interest (with rejected planet candidates) is used as a control for comparison of multiplicity statistics. The lucky-imaging technique used in this work is compared to other adaptive optics and speckle imaging observations of Kepler planet host candidates. To that end, we define a new parameter, the blended source confidence level (BSC), to assess the probability of an object to have blended non-detected eclipsing binaries capable of producing the detected transit. Results: We find that 67.2% of the observed Kepler hosts are isolated within our detectability limits, and 32.8% have at least one visual companion at angular separations below 6 arcsec. Indeed, we find close companions (below 3 arcsec) for the 17.2% of the sample. The planet properties of

  19. Planet X revamped after the discovery of the Sedna-like object 2012 VP113?

    Science.gov (United States)

    Iorio, L.

    2014-10-01

    The recent discovery of the Sedna-like dwarf planet 2012 VP113 by Trujillo and Sheppard has revamped the old-fashioned hypothesis that a still unseen trans-Plutonian object of planetary size, variously dubbed over the years as Planet X, Tyche and Telisto, might lurk in the distant peripheries of the Solar system. This time, the presence of a super-Earth with mass mX =2-15 m⊕ at a distance dX ≈ 200-300 astronomical units (au) has been proposed to explain the observed clustering of the arguments of perihelion ω near ω ≈ 0° but not ω ≈ 180° for Sedna, 2012 VP113 and other minor bodies of the Solar system with perihelion distances q > 30 au and semimajor axes a > 150 au. Actually, such a scenario is strongly disfavoured by the latest constraints Δ dot{\\varpi } on the anomalous perihelion precessions of some Solar system planets obtained with the INPOP and EPM ephemerides. Indeed, they yield dX ≳ 496-570 au (mX = 2 m⊕) and dX ≳ 970-1111 au (mX = 15 m⊕). Much tighter constraints could be obtained in the near future from the New Horizons mission to Pluto.

  20. THE VLA VIEW OF THE HL TAU DISK: DISK MASS, GRAIN EVOLUTION, AND EARLY PLANET FORMATION

    Energy Technology Data Exchange (ETDEWEB)

    Carrasco-González, Carlos; Rodríguez, Luis F.; Galván-Madrid, Roberto [Instituto de Radioastronomía y Astrofísica UNAM, Apartado Postal 3-72 (Xangari), 58089 Morelia, Michoacán, México (Mexico); Henning, Thomas; Linz, Hendrik; Birnstiel, Til; Boekel, Roy van; Klahr, Hubert [Max-Planck-Institut für Astronomie Heidelberg, Königstuhl 17, D-69117 Heidelberg (Germany); Chandler, Claire J.; Pérez, Laura [National Radio Astronomy Observatory, P.O. Box O, 1003 Lopezville Road, Socorro, NM 87801-0387 (United States); Anglada, Guillem; Macias, Enrique; Osorio, Mayra [Instituto de Astrofísica de Andalucía (CSIC), Apartado 3004, E-18080 Granada (Spain); Flock, Mario [Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109 (United States); Menten, Karl [Jansky Fellow of the National Radio Astronomy Observatory (United States); Testi, Leonardo [European Southern Observatory, Karl-Schwarzschild-Str. 2, D-85748 Garching bei München (Germany); Torrelles, José M. [Institut de Ciències de l’Espai (CSIC-IEEC) and Institut de Ciències del Cosmos (UB-IEEC), Martí i Franquès 1, E-08028 Barcelona (Spain); Zhu, Zhaohuan, E-mail: c.carrasco@crya.unam.mx, E-mail: l.rodriguez@crya.unam.mx, E-mail: r.galvan@crya.unam.mx, E-mail: henning@mpia.de, E-mail: linz@mpia.de [Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544 (United States)

    2016-04-10

    The first long-baseline ALMA campaign resolved the disk around the young star HL Tau into a number of axisymmetric bright and dark rings. Despite the very young age of HL Tau, these structures have been interpreted as signatures for the presence of (proto)planets. The ALMA images triggered numerous theoretical studies based on disk–planet interactions, magnetically driven disk structures, and grain evolution. Of special interest are the inner parts of disks, where terrestrial planets are expected to form. However, the emission from these regions in HL Tau turned out to be optically thick at all ALMA wavelengths, preventing the derivation of surface density profiles and grain-size distributions. Here, we present the most sensitive images of HL Tau obtained to date with the Karl G. Jansky Very Large Array at 7.0 mm wavelength with a spatial resolution comparable to the ALMA images. At this long wavelength, the dust emission from HL Tau is optically thin, allowing a comprehensive study of the inner disk. We obtain a total disk dust mass of (1–3) × 10{sup −3} M {sub ⊙}, depending on the assumed opacity and disk temperature. Our optically thin data also indicate fast grain growth, fragmentation, and formation of dense clumps in the inner densest parts of the disk. Our results suggest that the HL Tau disk may be actually in a very early stage of planetary formation, with planets not already formed in the gaps but in the process of future formation in the bright rings.

  1. The archaeal diversity in a cave system and its implications for life on other planets

    Science.gov (United States)

    Leuko, Stefan; Rettberg, Petra; De Waele, Jo; Bessone, Loredana; Sauro, Francesco; Sanna, Laura

    The quest of exploring and looking for life in new places is a human desire since centuries. Nowadays, we are not only looking on planet Earth any more, but our endeavours focus on nearby planets in our solar system. At this point in time, we are not able to send manned missions to other planets, but to be ready and prepared for the day, training today is pivotal. Developed by the European Space Agency (ESA) since 2008, these CAVES missions (Cooperative Adventure for Valuing and Exercising human behaviour and performance Skills), prepare astronauts to work safely and effectively and solve problems as a multicultural team while exploring uncharted underground natural areas (i.e. caves) using space procedures. The hypogean environment is also of great interest for astrobiological research as cave conditions may resemble those in extra-terrestrial environments. Besides the main focus of exploration and skill training, future astronauts are also trained in taking microbiological samples for analysis during the exploration and for further analysis in the lab. During the 2013 mission, astronauts collected soil samples and employed flocked swaps to sample areas with little or no visible soil. Microscopic analysis back in the lab revealed a diverse spectrum of different cell shapes and sizes. Samples were further analysed employing molecular tools such as RFLP analysis, 16s rRNA clone libraries and sequence analysis. RFLP pattern analysis revealed that the community can be divided in 9 main groups and several single patterns. The largest group (40% of all analysed clones) belong to the clade of ammonia oxidizing archaea Nitrosopumilus spp.. Dividing the results by sampling point, it showed that the highest diversity of organisms was located on the flocked swaps, which is interesting as the sample was taken from a rock surface with no visible organic matter. By analysis low energy systems like a cave, we may be able to find clues for what could be necessary to survive on a

  2. THE PHOTOECCENTRIC EFFECT AND PROTO-HOT JUPITERS. I. MEASURING PHOTOMETRIC ECCENTRICITIES OF INDIVIDUAL TRANSITING PLANETS

    Energy Technology Data Exchange (ETDEWEB)

    Dawson, Rebekah I. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, MS-10, Cambridge, MA 02138 (United States); Johnson, John Asher, E-mail: rdawson@cfa.harvard.edu [Department of Astronomy, California Institute of Technology, 1200 East California Boulevard, MC 249-17, Pasadena, CA 91125 (United States)

    2012-09-10

    Exoplanet orbital eccentricities offer valuable clues about the history of planetary systems. Eccentric, Jupiter-sized planets are particularly interesting: they may link the 'cold' Jupiters beyond the ice line to close-in hot Jupiters, which are unlikely to have formed in situ. To date, eccentricities of individual transiting planets primarily come from radial-velocity measurements. Kepler has discovered hundreds of transiting Jupiters spanning a range of periods, but the faintness of the host stars precludes radial-velocity follow-up of most. Here, we demonstrate a Bayesian method of measuring an individual planet's eccentricity solely from its transit light curve using prior knowledge of its host star's density. We show that eccentric Jupiters are readily identified by their short ingress/egress/total transit durations-part of the 'photoeccentric' light curve signature of a planet's eccentricity-even with long-cadence Kepler photometry and loosely constrained stellar parameters. A Markov Chain Monte Carlo exploration of parameter posteriors naturally marginalizes over the periapse angle and automatically accounts for the transit probability. To demonstrate, we use three published transit light curves of HD 17156 b to measure an eccentricity of e = 0.71{sup +0.16}{sub -0.09}, in good agreement with the discovery value e = 0.67 {+-} 0.08 based on 33 radial-velocity measurements. We present two additional tests using Kepler data. In each case, the technique proves to be a viable method of measuring exoplanet eccentricities and their confidence intervals. Finally, we argue that this method is the most efficient, effective means of identifying the extremely eccentric, proto-hot Jupiters predicted by Socrates et al.

  3. On the problem of the search for Planet X based on its perturbation of the outer planets

    Energy Technology Data Exchange (ETDEWEB)

    Gomes, R.S. (Observatorio Nacional, Rio de Janeiro (Brazil))

    1989-08-01

    The present consideration of the systematic residuals which emerge when Uranus and Neptune observations are compared to their theories will proceed from the supposition that these discrepancies are due to an unknown 'planet X'. An effort is accordingly made to ascertain the ideal region, rather than a specific position or positions, in which the existence of such a planet will account for the systematic residuals. The problematic relationship of the probable albedo of a planet X to the mass it must possess, in view of the present calculations, is assessed. 5 refs.

  4. Star-planet interactions. IV. Possibility of detecting the orbit-shrinking of a planet around a red giant

    Science.gov (United States)

    Meynet, Georges; Eggenberger, Patrick; Privitera, Giovanni; Georgy, Cyril; Ekström, Sylvia; Alibert, Yann; Lovis, Christophe

    2017-06-01

    The surface rotations of some red giants are so fast that they must have been spun up by tidal interaction with a close companion, either another star, a brown dwarf, or a planet. We focus here on the case of red giants that are spun up by tidal interaction with a planet. When the distance between the planet and the star decreases, the spin period of the star decreases, the orbital period of the planet decreases, and the reflex motion of the star increases. We study the change rate of these three quantities when the circular orbit of a planet of 15 MJ that initially orbits a 2 M⊙ star at 1 au shrinks under the action of tidal forces during the red giant phase. We use stellar evolution models coupled with computations of the orbital evolution of the planet, which allows us to follow the exchanges of angular momentum between the star and the orbit in a consistent way. We obtain that the reflex motion of the red giant star increases by more than 1 m s-1 per year in the last 40 yr before the planet engulfment. During this phase, the reflex motion of the star is between 660 and 710 m s-1. The spin period of the star increases by more than about 10 min per year in the last 3000 yr before engulfment. During this period, the spin period of the star is shorter than 0.7 yr. During this same period, the variation in orbital period, which is shorter than 0.18 yr, is on the same order of magnitude. Changes in reflex-motion and spin velocities are very small and thus most likely out of reach of being observed. The most promising way of detecting this effect is through observations of transiting planets, that is, through changes of the beginning or end of the transit. For the relatively long orbital periods expected around red giants, long observing runs of typically a few years are needed. Interesting star-planet systems that currently are in this stage of orbit-shrinking would be red giants with fast rotation (above typically 4-5 km s-1), a low surface gravity (log g lower

  5. Planetesimal-driven Migration of Giant Planet Cores in the Presence of a Gas Disk

    Science.gov (United States)

    Capobianco, Christopher; Duncan, M. J.; Levison, H. F.

    2009-05-01

    Planetesimal-driven migration has been shown to be an important dynamical mechanism for the formation of giant planet cores (Levison, Thommes & Duncan, in preparation); indeed this migration rate (Kirsh et al., 2009) is faster than nominal tidally-induced migration rates in gas disks (e.g., Type - I migration) for cores less than a few Earth masses. Our earlier work (Capobianco, Duncan and Levison, in preparation) neglected Type - I tidal torquing but included a prescription for aerodynamic gas drag (Adachi et al., 1976) on a population of equal-sized planetesimals. We demonstrated that the migration of cores in minimum mass solar nebulae can be self-sustaining in either the inward or outward direction. Outward migration is easily triggered and favoured only for a plausible (albeit narrow) range of planetesimal radii 1.0 km. This outward migration can be accompanied by substantial mass accretion. We have now included a prescription for Type - I orbital migration (Papaloizou & Larwood, 2000) for the giant planet cores, as well as a planetesimal size spectrum to mimic a collisional cascade. Our results indicate that the dynamics of the cores will be dominated by the planetesimals in the size range containing most of the mass of the planetesimal population. The inclusion of Type - I migration modifies our results for the tendency for outward versus inward migration, but surprisingly we find that, once initiated, outward migration of the cores can be maintained despite the presence of inward Type - I torquing.

  6. Climate variations on Earth-like circumbinary planets.

    Science.gov (United States)

    Popp, Max; Eggl, Siegfried

    2017-04-06

    The discovery of planets orbiting double stars at close distances has sparked increasing scientific interest in determining whether Earth-analogues can remain habitable in such environments and how their atmospheric dynamics is influenced by the rapidly changing insolation. In this work we present results of the first three-dimensional numerical experiments of a water-rich planet orbiting a double star. We find that the periodic forcing of the atmosphere has a noticeable impact on the planet's climate. Signatures of the forcing frequencies related to the planet's as well as to the binary's orbital periods are present in a variety of climate indicators such as temperature and precipitation, making the interpretation of potential observables challenging. However, for Earth-like greenhouse gas concentrations, the variable forcing does not change the range of insolation values allowing for habitable climates substantially.

  7. Climate variations on Earth-like circumbinary planets

    Science.gov (United States)

    Popp, Max; Eggl, Siegfried

    2017-04-01

    The discovery of planets orbiting double stars at close distances has sparked increasing scientific interest in determining whether Earth-analogues can remain habitable in such environments and how their atmospheric dynamics is influenced by the rapidly changing insolation. In this work we present results of the first three-dimensional numerical experiments of a water-rich planet orbiting a double star. We find that the periodic forcing of the atmosphere has a noticeable impact on the planet's climate. Signatures of the forcing frequencies related to the planet's as well as to the binary's orbital periods are present in a variety of climate indicators such as temperature and precipitation, making the interpretation of potential observables challenging. However, for Earth-like greenhouse gas concentrations, the variable forcing does not change the range of insolation values allowing for habitable climates substantially.

  8. MSX INFRARED MINOR PLANET SURVEY V1.0

    Data.gov (United States)

    National Aeronautics and Space Administration — The Midcourse Space Experiment Infrared Minor Planet Survey (MIMPS) includes infrared data for 168 main-belt asteroids serendipitously observed by the Midcourse...

  9. The early evolution of the atmospheres of terrestrial planets

    CERN Document Server

    Raulin, François; Muller, Christian; Nixon, Conor; Astrophysics and Space Science Proceedings : Volume 35

    2013-01-01

    “The Early Evolution of the Atmospheres of Terrestrial Planets” presents the main processes participating in the atmospheric evolution of terrestrial planets. A group of experts in the different fields provide an update of our current knowledge on this topic. Several papers in this book discuss the key role of nitrogen in the atmospheric evolution of terrestrial planets. The earliest setting and evolution of planetary atmospheres of terrestrial planets is directly associated with accretion, chemical differentiation, outgassing, stochastic impacts, and extremely high energy fluxes from their host stars. This book provides an overview of the present knowledge of the initial atmospheric composition of the terrestrial planets. Additionally it includes some papers about the current exoplanet discoveries and provides additional clues to our understanding of Earth’s transition from a hot accretionary phase into a habitable world. All papers included were reviewed by experts in their respective fields. We are ...

  10. The sun,the planets and life on Earth

    Science.gov (United States)

    Claudia, Tacu Cristina

    2017-04-01

    We all knowthat Earth,our planet,it's not alone in the Universe.We will discover together a few of its secrets: 0 The influence of the sun on our planet is very important.It provides us thelight ,the warnith and the enery without whice life on Earth wouldn't be possible. 0 Thank to the Sun and the endless spinning of our planet around its own axe and, at the same time around this star,we receive as a gift the day,the night,the seasons. 0In our Solar System there are other spheres appart from the Sun and planets -the asteroids ,wandering pieces of stone.It is said that many milions of years ago it they made a lot of plants and animals disappear. If I have arisen your curiosity,let's go!

  11. Junkyard planet: travels in the billion-dollar trash trade

    National Research Council Canada - National Science Library

    Minter, Adam

    2013-01-01

    .... In Junkyard Planet, Adam Minter-- veteran journalist and son of an American junkyard owner-- travels deeply into a vast, often hidden, multibillion-dollar industry that's transforming our economy and environment...

  12. The quest for very low-mass planets

    Energy Technology Data Exchange (ETDEWEB)

    Mayor, M; Udry, S [Geneva Observatory, Geneva University, 51 ch des Maillettes, CH-1290 Versoix (Switzerland)], E-mail: michel.mayor@obs.unige.ch

    2008-08-15

    The statistical results gathered on exoplanet properties over the past decade provide strong constraints for planet-formation models. They now prove to be especially important for the new category of very low-mass solid planets recently revealed by improved radial velocities, obtained mainly with the HARPS spectrograph. We review here the emerging properties of this newly discovered population, in the light of results from state-of-the-art planet-formation models. We also discuss the limitations of the radial-velocity method and the associated optimistic perspectives for the future detection of Earth-like planets in the Habitable Zone of solar-type stars, with radial velocities alone or in complement to space photometry.

  13. Earth-type planets (Mercury, Venus, and Mars)

    Science.gov (United States)

    Marov, M. Y.; Davydov, V. D.

    1975-01-01

    Spacecraft- and Earth-based studies on the physical nature of the planets Mercury, Venus, and Mars are reported. Charts and graphs are presented on planetary surface properties, rotational parameters, atmospheric compositions, and astronomical characteristics.

  14. Earthlike planets: Surfaces of Mercury, Venus, earth, moon, Mars

    Science.gov (United States)

    Murray, B.; Malin, M. C.; Greeley, R.

    1981-01-01

    The surfaces of the earth and the other terrestrial planets of the inner solar system are reviewed in light of the results of recent planetary explorations. Past and current views of the origin of the earth, moon, Mercury, Venus and Mars are discussed, and the surface features characteristic of the moon, Mercury, Mars and Venus are outlined. Mechanisms for the modification of planetary surfaces by external factors and from within the planet are examined, including surface cycles, meteoritic impact, gravity, wind, plate tectonics, volcanism and crustal deformation. The origin and evolution of the moon are discussed on the basis of the Apollo results, and current knowledge of Mercury and Mars is examined in detail. Finally, the middle periods in the history of the terrestrial planets are compared, and future prospects for the exploration of the inner planets as well as other rocky bodies in the solar system are discussed.

  15. ERA-PLANET THE EUROPEAN NETWORK FOR OBSERVING OUR CHANGING PLANET

    Directory of Open Access Journals (Sweden)

    N. Pirrone

    2016-06-01

    Full Text Available In the last decade a significant number of projects and programmes in different domains of Earth Observation and environmental monitoring have generated a substantial amount of data and knowledge on different aspects related to environmental quality and sustainability. Big data generated by in-situ or satellite platforms are being collected and archived with a plethora of systems and instruments making difficult the sharing of data and transfer of knowledge to stakeholders and policy makers to support key economic and societal sectors. The overarching goal of ERAPLANET is to strengthen the European Research Area in the domain of Earth Observation in coherence with the European participation in the Group on Earth Observation (GEO and Copernicus. The expected impact is to strengthen European leadership within the forthcoming GEO 2015-2025 Work Plan. ERA-PLANET is designed to reinforce the interface with user communities, whose needs the Global Earth Observation System of Systems (GEOSS intends to address. It will provide more accurate, comprehensive and authoritative information to policy and decision-makers in key societal benefit areas, such as Smart Cities and Resilient Societies; Resource efficiency and Environmental management; Global changes and Environmental treaties; Polar areas and Natural resources. ERA-PLANET will provide advanced decision-support tools and technologies aimed to better monitor our global environment and share the information and knowledge available in the different domains of Earth Observation.

  16. Masses, Radii, and Cloud Properties of the HR 8799 Planets

    Science.gov (United States)

    Marley, Mark S.; Saumon, Didier; Cushing, Michael; Ackerman, Andrew S.; Fortney, Jonathan J.; Freedman, Richard

    2012-01-01

    The near-infrared colors of the planets directly imaged around the A star HR 8799 are much redder than most field brown dwarfs of the same effective temperature. Previous theoretical studies of these objects have compared the photometric and limited spectral data of the planets to the predictions of various atmosphere and evolution models and concluded that the atmospheres of planets b, c, and d are unusually cloudy or have unusual cloud properties. Most studies have also found that the inferred radii of some or all of the planets disagree with expectations of standard giant planet evolution models. Here we compare the available data to the predictions of our own set of atmospheric and evolution models that have been extensively tested against field L and T dwarfs, including the reddest L dwarfs. Unlike almost all previous studies we specify mutually self-consistent choices for effective temperature, gravity, cloud properties, and planetary radius. This procedure yields plausible and self-consistent values for the masses, effective temperatures, and cloud properties of all three planets. We find that the cloud properties of the HR 8799 planets are in fact not unusual but rather follow previously recognized trends including a gravity dependence on the temperature of the L to T spectral transition, some reasons for which we discuss. We find that the inferred mass of planet b is highly sensitive to the H and K band spectrum. Solutions for planets c and particularly d are less certain but are consistent with the generally accepted constraints on the age of the primary star and orbital dynamics. We also confirm that as for L and T dwarfs and solar system giant planets, non-equilibrium chemistry driven by atmospheric mixing is also important for these objects. Given the preponderance of data suggesting that the L to T spectral type transition is gravity dependent, we present a new evolution calculation that predicts cooling tracks on the near-infrared color

  17. The interplay between X-ray photoevaporation and planet formation

    Science.gov (United States)

    Rosotti, Giovanni; Ercolano, Barbara; Owen, James; Armitage, Phil

    2013-07-01

    Planets form from gas and dust discs that orbit young stars. The evolution and final dispersal of protoplanetary discs holds therefore a particular importance, especially in terms of timescales. In particular, observations reveal that most (if not all) discs go through the "transitional disc" phase, which is currently interpreted as the last stage before the disc dispersal. Photoevaporation and planet formation have been studied as possible physical mechanisms responsible for the formation of these discs. While it is likely that more than one mechanism is at play, the interplay between them has until now not been studied in detail. I will show results from 2d simulations of protoplanetary discs undergoing X-ray photoevaporation with an embedded giant planet. By reducing the mass accretion flow onto the star, discs thatw form giant planets will be dispersed at earlier times than discs without planets by X-ray photoevaporation. This process, planet formation induced photoevaporation (PIPE), is able to produce transition disc that for a given mass accretion rate have larger holes when compared to standard X-ray photoevaporation. This constitutes a possible route for the formation of the observed class of accreting transition discs with large holes, which are otherwise difficult to explain by planet formation or photoevaporation alone. Moreover, assuming that a planet is able to filter dust completely, PIPE produces a transition disc with a large hole and may provide a mechanism to quickly shut down accretion. This process appears to be too slow however to explain the observed desert in the population of transition disc with large holes and low mass accretion rates.

  18. X-ray insights into star and