A SEARCH FOR SHORT-PERIOD ROCKY PLANETS AROUND WDs WITH THE COSMIC ORIGINS SPECTROGRAPH (COS)

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Sandhaus, Phoebe H.; Debes, John H.; Ely, Justin; Hines, Dean C.; Bourque, Matthew [Space Telescope Science Institute, 3700 San Martin Dr., Baltimore, MD 21218 (United States)

2016-05-20

The search for transiting habitable exoplanets has broadened to include several types of stars that are smaller than the Sun in an attempt to increase the observed transit depth and hence the atmospheric signal of the planet. Of all spectral types, white dwarfs (WDs) are the most favorable for this type of investigation. The fraction of WDs that possess close-in rocky planets is unknown, but several large angle stellar surveys have the photometric precision and cadence to discover at least one if they are common. Ultraviolet observations of WDs may allow for detection of molecular oxygen or ozone in the atmosphere of a terrestrial planet. We use archival Hubble Space Telescope data from the Cosmic Origins Spectrograph to search for transiting rocky planets around UV-bright WDs. In the process, we discovered unusual variability in the pulsating WD GD 133, which shows slow sinusoidal variations in the UV. While we detect no planets around our small sample of targets, we do place stringent limits on the possibility of transiting planets, down to sub-lunar radii. We also point out that non-transiting small planets in thermal equilibrium are detectable around hotter WDs through infrared excesses, and identify two candidates.

Types of Information Expected from a Photometric Search for Extra-Solar Planets

Science.gov (United States)

Borucki, William; Koch, David; Bell, James, III; Cuzzi, Jeffrey N. (Technical Monitor)

1994-01-01

The current theory postulates that planets are a consequence of the formation of stars from viscous accretion disks. Condensation from the hotter, inner portion of the accretion disk favors the formation of small rocky planets in the inner portion and the formation of gas giants in the cuter, cooler part. Consequently, terrestrial-type planets in inner orbits must be commonplace (Wetheril 1991). From the geometry of the situation (Borucki and Summers 1984), it can be shown that 1% of those planetary systems that resemble our solar system should show transits for Earth-sized (or larger) planets. Thus a photometric satellite that uses a wide field of view telescope and a large CCD array to simultaneously monitor 5000 target stars should detect 50 planetary systems. To verify that regularly recurring transits are occurring rather than statistical fluctuations of the stellar flux, demands observations that extend over several orbital periods so that the constancy of the orbital period, signal amplitude, and duration can be measured. Therefore, to examine the region from Mercury's orbit to that of the Earth requires a duration of three years whereas a search out to the orbit of mars requires about six years. The results of the observations should provide estimates of the distributions of planetary size and orbital radius, and the frequency of planetary systems that have Earth-sized planets in inner orbits. Because approximately one half of the star systems observed will be binary systems, the frequency of planetary systems orbit ' ing either one or both of the stars can also be determined. Furthermore, the complexity of the photometric signature of a planet transiting a pair of stars provides enough information to estimate the eccentricities of the planetary orbits. In summary, the statistical evidence from a photometric search of solar-like stars should be able to either confirm or deny the applicability of the current theory of planet formation and provide new

The Kepler Mission: A Search for Terrestrial Planets - Development Status

Science.gov (United States)

Koch, David; Borucki, W.; Mayer, D.; Caldwell, D.; Jenkens, J.; Dunham, E.; Geary, J.; Bachtell, E.; Deininger, W.; Philbrick, R.

2003-01-01

We have embarked on a mission to detect terrestrial planets. The space mission has been optimized to search for earth-size planets (0.5 to 10 earth masses) in the habitable zone (HZ) of solar-like stars. Given this design, the mission will necessarily be capable of not only detecting Earth analogs, but a wide range of planetary types and characteristics ranging from Mercury-size objects with orbital periods of days to gas-giants in decade long orbits that have undeniable signatures even with only one transit detected. The mission is designed to survey the full range of spectral-type dwarf stars. The approach is to detect the periodic signal of transiting planets. Three or more transits of a star exceeding a combined threshold of eight sigma with a statistically consistent period, brightness change and duration provide a rigorous method of detection. From the relative brightness change the planet size can be calculated. From the period the orbital size can be calculated and its location relative to the HZ determined. Presented here are: the mission goals, the top level system design requirements derived from these goals that drive the flight system design, a number of the trades that have lead to the mission concept, expected photometric performance dependence on stellar brightness and spectral type based on the system 'noise tree' analysis. Updated estimates are presented of the numbers of detectable planets versus size, orbit, stellar spectral type and distances based on a planet frequency hypothesis. The current project schedule and organization are given.

A Planet for Goldilocks: The Search for Evidence of Life Beyond Earth

Science.gov (United States)

Batalha, Natalie M.

2018-01-01

A Planet for Goldilocks: The Search for Evidence of Life Beyond Earth "Not too hot, not too cold" begins the prescription for a world that's just right for life as we know it. Finding evidence of life beyond Earth is one of the primary goals of science agencies around the world thanks in large part to NASA's Kepler Mission which launched in 2009 with the objective of finding Goldilocks planets orbiting other stars like our Sun. Indeed, the space telescope opened our eyes to the terrestrial-sized planets that populate the galaxy as well as exotic worlds unlike anything that exists in the solar system. The mission ignited the search for life beyond earth via remote detection of atmospheric biosignatures on exoplanets. Most recently, our collective imagination was awakened by the discovery of Goldilocks worlds orbiting some of the nearest neighbors to the Sun, turning abstractions into destinations. Dr. Batalha will give an overview of the science legacy of the Kepler Mission and other key discoveries. She'll give a preview of what's to come by highlighting the missions soon to launch and those that are concepts taking shape on the drawing board.

Predictions of Planet Detections with Near-infrared Radial Velocities in the Upcoming SPIRou Legacy Survey-planet Search

Science.gov (United States)

Cloutier, Ryan; Artigau, Étienne; Delfosse, Xavier; Malo, Lison; Moutou, Claire; Doyon, René; Donati, Jean-Francois; Cumming, Andrew; Dumusque, Xavier; Hébrard, Élodie; Menou, Kristen

2018-02-01

The SPIRou near-infrared spectropolarimeter is destined to begin science operations at the Canada–France–Hawaii Telescope in mid-2018. One of the instrument’s primary science goals is to discover the closest exoplanets to the solar system by conducting a three- to five-year long radial velocity survey of nearby M dwarfs at an expected precision of ∼1 m s‑1, the SPIRou Legacy Survey-Planet Search (SLS-PS). In this study, we conduct a detailed Monte Carlo simulation of the SLS-PS using our current understanding of the occurrence rate of M dwarf planetary systems and physical models of stellar activity. From simultaneous modeling of planetary signals and activity, we predict the population of planets to be detected in the SLS-PS. With our fiducial survey strategy and expected instrument performance over a nominal survey length of ∼3 years, we expect SPIRou to detect {85.3}-12.4+29.3 planets including {20.0}-7.2+16.8 habitable-zone planets and {8.1}-3.2+7.6 Earth-like planets from a sample of 100 M1–M8.5 dwarfs out to 11 pc. By studying mid-to-late M dwarfs previously inaccessible to existing optical velocimeters, SPIRou will put meaningful constraints on the occurrence rate of planets around those stars including the value of {η }\\oplus at an expected level of precision of ≲ 45 % . We also predict that a subset of {46.7}-6.0+16.0 planets may be accessible with dedicated high-contrast imagers on the next generation of extremely large telescopes including {4.9}-2.0+4.7 potentially imagable Earth-like planets. Lastly, we compare the results of our fiducial survey strategy to other foreseeable survey versions to quantify which strategy is optimized to reach the SLS-PS science goals. The results of our simulations are made available to the community on GitHub (https://github.com/r-cloutier/SLSPS_Simulations).

Photometric Detection of Extra-Solar Planets

Science.gov (United States)

Hatzes, Artie P.; Cochran, William D.

2004-01-01

This NASA Origins Program grant supported the TEMPEST Texas McDonald Photometric Extrasolar Search for Transits) program at McDonald Observatory, which searches for transits of extrasolar planets across the disks of their parent stars. The basic approach is to use a wide-field ground-based telescope (in our case the McDonald Observatory 0.76m telescope and it s Prime Focus Corrector) to search for transits of short period (1-15 day orbits) of close-in hot-Jupiter planets in orbit around a large sample of field stars. The next task is to search these data streams for possible transit events. We collected our first set of test data for this program using the 0.76 m PFC in the summer of 1998. From those data, we developed the optimal observing procedures, including tailoring the stellar density, exposure times, and filters to best-suit the instrument and project. In the summer of 1999, we obtained the first partial season of data on a dedicated field in the constellation Cygnus. These data were used to develop and refine the reduction and analysis procedures to produce high-precision photometry and search for transits in the resulting light curves. The TeMPEST project subsequently obtained three full seasons of data on six different fields using the McDonald Observatory 0.76m PFC.

Double-blind test program for astrometric planet detection with Gaia

Science.gov (United States)

Casertano, S.; Lattanzi, M. G.; Sozzetti, A.; Spagna, A.; Jancart, S.; Morbidelli, R.; Pannunzio, R.; Pourbaix, D.; Queloz, D.

2008-05-01

planetary systems, will discover and measure several thousands of giant planets out to 3-4 AUs from stars within 200 pc, and will characterize hundreds of multiple-planet systems, including meaningful coplanarity tests. Finally, we put Gaia's planet discovery potential into context, identifying several areas of planetary-system science (statistical properties and correlations, comparisons with predictions from theoretical models of formation and evolution, interpretation of direct detections) in which Gaia can be expected, on the basis of our results, to have a relevant impact, when combined with data coming from other ongoing and future planet search programs.

Hubble 2020: Outer Planet Atmospheres Legacy (OPAL) Program

Science.gov (United States)

Simon, Amy

2017-08-01

Long time base observations of the outer planets are critical in understanding the atmospheric dynamics and evolution of the gas giants. We propose yearly monitoring of each giant planet for the remainder of Hubble's lifetime to provide a lasting legacy of increasingly valuable data for time-domain studies. The Hubble Space Telescope is a unique asset to planetary science, allowing high spatial resolution data with absolute photometric knowledge. For the outer planets, gas/ice giant planets Jupiter, Saturn, Uranus and Neptune, many phenomena happen on timescales of years to decades, and the data we propose are beyond the scope of a typical GO program. Hubble is the only platform that can provide high spatial resolution global studies of cloud coloration, activity, and motion on a consistent time basis to help constrain the underlying mechanics.

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.

Characterizing the Habitable Zone Planets of Kepler Stars

Science.gov (United States)

Fischer, Debra

than 100 days or they use extrapolation to estimate planet occurrence rates beyond 100 days. The new detections of transit candidates at wider separations and the incompleteness analysis will be used to carry out an analysis of the architecture of exoplanetary systems from 1 5 AU. We are synthesizing a statistical description with information from short-period Kepler transits, the longer period Kepler transit candidates from this proposal, a completeness analysis of radial velocity data, and statistical information from microlensing. While our architecture analysis will only sketch out the bare bones of planetary systems (massive or large planets), this is still a novel analysis that may point to the location of rocky planets if packed planetary systems prevail. Finally, we will expand our guest scientist program for serendipitous discoveries. We have already partnered with scientists who are searching for cataclysmic variables, heartbeat stars, and exomoons. Our undergrad students have already carried out summer research as guest scientists to characterize inflated jupiters, search for Trojan planets, and to search for microlensing events.

Zodiacal Exoplanets in Time (ZEIT). V. A Uniform Search for Transiting Planets in Young Clusters Observed by K2

Science.gov (United States)

Rizzuto, Aaron C.; Mann, Andrew W.; Vanderburg, Andrew; Kraus, Adam L.; Covey, Kevin R.

2017-12-01

Detection of transiting exoplanets around young stars is more difficult than for older systems owing to increased stellar variability. Nine young open cluster planets have been found in the K2 data, but no single analysis pipeline identified all planets. We have developed a transit search pipeline for young stars that uses a transit-shaped notch and quadratic continuum in a 12 or 24 hr window to fit both the stellar variability and the presence of a transit. In addition, for the most rapid rotators ({P}{rot}Pleiades, Hyades, Praesepe) and conduct a uniform search of the members. We identify all known transiting exoplanets in the clusters, 17 eclipsing binaries, one transiting planet candidate orbiting a potential Pleiades member, and three orbiting unlikely members of the young clusters. Limited injection recovery testing on the known planet hosts indicates that for the older Praesepe systems we are sensitive to additional exoplanets as small as 1-2 R ⊕, and for the larger Upper Scorpius planet host (K2-33) our pipeline is sensitive to ˜4 R ⊕ transiting planets. The lack of detected multiple systems in the young clusters is consistent with the expected frequency from the original Kepler sample, within our detection limits. With a robust pipeline that detects all known planets in the young clusters, occurrence rate testing at young ages is now possible.

The SOPHIE search for northern extrasolar planets. X. Detection and characterization of giant planets by the dozen

Science.gov (United States)

Hébrard, G.; Arnold, L.; Forveille, T.; Correia, A. C. M.; Laskar, J.; Bonfils, X.; Boisse, I.; Díaz, R. F.; Hagelberg, J.; Sahlmann, J.; Santos, N. C.; Astudillo-Defru, N.; Borgniet, S.; Bouchy, F.; Bourrier, V.; Courcol, B.; Delfosse, X.; Deleuil, M.; Demangeon, O.; Ehrenreich, D.; Gregorio, J.; Jovanovic, N.; Labrevoir, O.; Lagrange, A.-M.; Lovis, C.; Lozi, J.; Moutou, C.; Montagnier, G.; Pepe, F.; Rey, J.; Santerne, A.; Ségransan, D.; Udry, S.; Vanhuysse, M.; Vigan, A.; Wilson, P. A.

2016-04-01

We present new radial velocity measurements of eight stars that were secured with the spectrograph SOPHIE at the 193 cm telescope of the Haute-Provence Observatory. The measurements allow detecting and characterizing new giant extrasolar planets. The host stars are dwarfs of spectral types between F5 and K0 and magnitudes of between 6.7 and 9.6; the planets have minimum masses Mp sin I of between 0.4 to 3.8 MJup and orbitalperiods of several days to several months. The data allow only single planets to be discovered around the first six stars (HD 143105, HIP 109600, HD 35759, HIP 109384, HD 220842, and HD 12484), but one of them shows the signature of an additional substellar companion in the system. The seventh star, HIP 65407, allows the discovery of two giant planets that orbit just outside the 12:5 resonance in weak mutual interaction. The last star, HD 141399, was already known to host a four-planet system; our additional data and analyses allow new constraints to be set on it. We present Keplerian orbits of all systems, together with dynamical analyses of the two multi-planet systems. HD 143105 is one of the brightest stars known to host a hot Jupiter, which could allow numerous follow-up studies to be conducted even though this is not a transiting system. The giant planets HIP 109600b, HIP 109384b, and HD 141399c are located in the habitable zone of their host star. Based on observations collected with the SOPHIE spectrograph on the 1.93-m telescope at Observatoire de Haute-Provence (CNRS), France, by the SOPHIE Consortium (programs 07A.PNP.CONS to 15A.PNP.CONS).Full version of the SOPHIE measurements (Table 1) is only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/588/A145

The Earth as a Distant Planet A Rosetta Stone for the Search of Earth-Like Worlds

CERN Document Server

Vázquez, M; Montañés Rodríguez, P

2010-01-01

Is the Earth, in some way, special? Or is our planet but one of the millions of other inhabited planets within our galaxy? This is an exciting time to be asking this old question, because for the first time in history, the answer is within reach. In The Earth as a Distant Planet, the authors set themselves as external observers of our Solar System from an astronomical distance. From that perspective, the authors describe how the Earth, the third planet in distance to the central star, can be catalogued as having its own unique features and as capable of sustaining life. The knowledge gained from this original perspective is then applied to the ongoing search for planets outside the solar system, or exoplanets. Since the discovery in 1992 of the first exoplanet, the number of known planets has increased exponentially. Ambitious space missions are already being designed for the characterization of their atmospheres and to explore the possibility that they host life. The exploration of Earth and the rest of the ...

Searching for ET with Help from Three Million Volunteers: The SETI@Home, Serendip, Sevendip and Spck SETI Programs

Science.gov (United States)

Werthimer, Dan; Anderson, David; Bowyer, Stuart; Cobb, Jeff; Demorest, Paul

2002-01-01

We summarize results from two radio and two optical SETI programs based at the University of California, Berkeley. We discuss the most promising candidate signals from these searches and present plans for future SETI searches, including SERENDIP V and SETI@home II. The ongoing SERENDIP sky survey searches for radio signals at the 300 meter Arecibo Observatory. SERENDIP IV uses a 168 million channel spectrum analyser and a dedicated receiver to take data 24 hours a day, year round. The sky survey covers a 100 MHz band centered at the 21 cm line (1420 MHz) and declinations from -2 to +38 degrees. SETI@home uses desktop computers of 3.5 million volunteers to analyse 50 Terabytes of data taken at Arecibo. The SETI@home sky survey is 10 times more sensitive and searches a much wider variety of signal types than SERRENDIP IV but covers only a 2.5 MHz band. SETI@home is the planet's largest supercomputer, averaging 25 Tflops. SETI@home participants have contributed over a million years of computing time so far. The SEVENDIP optical pulse search looks for nS time scale pulses at optical wavelengths. It utilizes an automated 30 inch telescope, three ultra fast photo multiplier tubes and a coincidence detector. The target list includes F,G,K and M stars, globular cluster and galaxies. The SPOCK optical SETI program searches for narrow band continuous signals using spectra taken by Marcy and his colleagues in their planet search at Keck observatory.

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.

Characterization and Validation of Transiting Planets in the TESS SPOC Pipeline

Science.gov (United States)

Twicken, Joseph D.; Caldwell, Douglas A.; Davies, Misty; Jenkins, Jon Michael; Li, Jie; Morris, Robert L.; Rose, Mark; Smith, Jeffrey C.; Tenenbaum, Peter; Ting, Eric; Wohler, Bill

2018-06-01

Light curves for Transiting Exoplanet Survey Satellite (TESS) target stars will be extracted and searched for transiting planet signatures in the Science Processing Operations Center (SPOC) Science Pipeline at NASA Ames Research Center. Targets for which the transiting planet detection threshold is exceeded will be processed in the Data Validation (DV) component of the Pipeline. The primary functions of DV are to (1) characterize planets identified in the transiting planet search, (2) search for additional transiting planet signatures in light curves after modeled transit signatures have been removed, and (3) perform a comprehensive suite of diagnostic tests to aid in discrimination between true transiting planets and false positive detections. DV data products include extensive reports by target, one-page summaries by planet candidate, and tabulated transit model fit and diagnostic test results. DV products may be employed by humans and automated systems to vet planet candidates identified in the Pipeline. TESS will launch in 2018 and survey the full sky for transiting exoplanets over a period of two years. The SPOC pipeline was ported from the Kepler Science Operations Center (SOC) codebase and extended for TESS after the mission was selected for flight in the NASA Astrophysics Explorer program. We describe the Data Validation component of the SPOC Pipeline. The diagnostic tests exploit the flux (i.e., light curve) and pixel time series associated with each target to support the determination of the origin of each purported transiting planet signature. We also highlight the differences between the DV components for Kepler and TESS. Candidate planet detections and data products will be delivered to the Mikulski Archive for Space Telescopes (MAST); the MAST URL is archive.stsci.edu/tess. Funding for the TESS Mission has been provided by the NASA Science Mission Directorate.

PLANET HUNTERS: ASSESSING THE KEPLER INVENTORY OF SHORT-PERIOD PLANETS

International Nuclear Information System (INIS)

Schwamb, Megan E.; Lintott, Chris J.; Lynn, Stuart; Smith, Arfon M.; Simpson, Robert J.; Fischer, Debra A.; Giguere, Matthew J.; Brewer, John M.; Parrish, Michael; Schawinski, Kevin

2012-01-01

We present the results from a search of data from the first 33.5 days of the Kepler science mission (Quarter 1) for exoplanet transits by the Planet Hunters citizen science project. Planet Hunters enlists members of the general public to visually identify transits in the publicly released Kepler light curves via the World Wide Web. Over 24,000 volunteers reviewed the Kepler Quarter 1 data set. We examine the abundance of ≥2 R ⊕ planets on short-period ( ⊕ Planet Hunters ≥85% efficient at identifying transit signals for planets with periods less than 15 days for the Kepler sample of target stars. Our high efficiency rate for simulated transits along with recovery of the majority of Kepler ≥4 R ⊕ planets suggests that the Kepler inventory of ≥4 R ⊕ short-period planets is nearly complete.

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.

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.

THE PAN-PACIFIC PLANET SEARCH. II. CONFIRMATION OF A TWO-PLANET SYSTEM AROUND HD 121056

Energy Technology Data Exchange (ETDEWEB)

Wittenmyer, Robert A.; Tinney, C. G. [School of Physics, University of New South Wales, Sydney, NSW 2052 (Australia); Wang, Liang [Key Laboratory of Optical Astronomy, National Astronomical Observatories, Chinese Academy of Sciences, A20 Datun Road, Chaoyang District, Beijing 100012 (China); Liu, Fan [Research School of Astronomy and Astrophysics, Australian National University, Cotter Road, Weston Creek, ACT 2611 (Australia); Horner, Jonathan [Australian Centre for Astrobiology, University of New South Wales, Sydney, NSW 2052 (Australia); Endl, Michael [McDonald Observatory, University of Texas at Austin, 1 University Station C1400, Austin, TX 78712 (United States); Johnson, John Asher [Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138 (United States); Carter, B. D., E-mail: rob@unsw.edu.au [Computational Engineering and Science Research Centre, University of Southern Queensland, Toowoomba, Queensland 4350 (Australia)

2015-02-10

Precise radial velocities from the Anglo-Australian Telescope (AAT) confirm the presence of a rare short-period planet around the K0 giant HD 121056. An independent two-planet solution using the AAT data shows that the inner planet has P = 89.1 ± 0.1 days, and m sin i = 1.35 ± 0.17 M{sub Jup}. These data also confirm the planetary nature of the outer companion, with m sin i = 3.9 ± 0.6 M{sub Jup} and a = 2.96 ± 0.16 AU. HD 121056 is the most-evolved star to host a confirmed multiple-planet system, and is a valuable example of a giant star hosting both a short-period and a long-period planet.

THE PAN-PACIFIC PLANET SEARCH. II. CONFIRMATION OF A TWO-PLANET SYSTEM AROUND HD 121056

International Nuclear Information System (INIS)

Wittenmyer, Robert A.; Tinney, C. G.; Wang, Liang; Liu, Fan; Horner, Jonathan; Endl, Michael; Johnson, John Asher; Carter, B. D.

2015-01-01

Precise radial velocities from the Anglo-Australian Telescope (AAT) confirm the presence of a rare short-period planet around the K0 giant HD 121056. An independent two-planet solution using the AAT data shows that the inner planet has P = 89.1 ± 0.1 days, and m sin i = 1.35 ± 0.17 M Jup . These data also confirm the planetary nature of the outer companion, with m sin i = 3.9 ± 0.6 M Jup and a = 2.96 ± 0.16 AU. HD 121056 is the most-evolved star to host a confirmed multiple-planet system, and is a valuable example of a giant star hosting both a short-period and a long-period planet

The Unlikely Origins of NASA’s “Search for Origins” Program

Science.gov (United States)

Perez, Mario R.; Thronson, Harley A.

2017-01-01

NASA’s Origins Program for many years was by far one of the most important scientific initiatives in NASA’s history, linking together priority research campaigns in planetary science, astrophysics, and the biological sciences. It served also as an overarching description to the agency stakeholders of a new generation of major space missions and technology investments. Moreover, the Program, although no longer formally in existence, significantly influences multiple major science priorities for NASA even today. Remarkably, inception of NASA’s Origins Program — The Search for Our Cosmic Roots — two decades ago was initiated by the country’s political leadership, not by the scientific community, the National Academy of Sciences, or by an advisory panel of experts. Instead, it was an initiative by the White House in response to the stunning announcement of ‘evidence’ for life found on a Martian meteorite not long after the discovery of the first extrasolar planet orbiting a sun-like star. A White House memo dated in September 1996, written by John H. Gibbons, Assistant to the President for Science and Technology to Dan Goldin, NASA Administrator at that time, called for a “Space Summit” that would include experts on three broad topics: the universe, planets, and life.The summit was jointly organized by NASA and the National Research Council, and was chaired by Vice-President Al Gore in late October 1996. Three dozen biologists, planetary scientists, astronomers, and cosmologists participated. The outcome was the Origins Program, which has been a prominent part of NASA’s science program ever since, theme which is captured by the simple and profound questions: How Did We Get Here? and Are We Alone?This particular initiative and its genesis demonstrates that science discoveries, followed by political activism and then executive orders can impact and shape for decades the paths to major science priorities, practices, and implementation. In this

Habitable Planets for Man

National Research Council Canada - National Science Library

Dole, Stephen H

2007-01-01

..., and discusses how to search for habitable planets. Interestingly for our time, he also gives an appraisal of the earth as a planet and describes how its habitability would be changed if some of its basic properties were altered...

Exoplanets search and characterization with the SOPHIE spectrograph at OHP

Directory of Open Access Journals (Sweden)

Hébrard G.

2011-02-01

Full Text Available Several programs of exoplanets search and characterization have been started with SOPHIE at the 1.93-m telescope of Haute-Provence Observatory, France. SOPHIE is an environmentally stabilized echelle spectrograph dedicated to high-precision radial velocity measurements. The objectives of these programs include systematic searches for exoplanets around different types of stars, characterizations of planet-host stars, studies of transiting planets through RossiterMcLaughlin effect, follow-up observations of photometric surveys. The instrument SOPHIE and a review of its latest results are presented here.

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.

The Problem of Extraterrestrial Civilizations and Extrasolar Planets

Science.gov (United States)

Mickaelian, A. M.

2015-07-01

The problem of extraterrestrial intelligence is the best example of multidisciplinary science. Here philosophy and religion, astronomy, radiophysics, spectrography, space flights and astronautics, geology and planetology, astroecology, chemistry and biology, history and archaeology, psychology, sociology, linguistics, diplomacy, UFOs and peculiar phenomena are involved. Among these many-sided studies, astronomers have probably displayed the most progress by discovering thousands of extrasolar planets. At present, a number of search programs are being accomplished, including those with space telescopes, and planets in so-called "habitable zone" are considered as most important ones, for which various orbital and physical parameters are being calculated. As the discovery of extraterrestrial life is the final goal, a special attention is given to Earth-like planets, for the discovery of which most sensitive technical means are necessary.

SEARCHING FOR THE SIGNATURES OF TERRESTRIAL PLANETS IN SOLAR ANALOGS

International Nuclear Information System (INIS)

Gonzalez Hernandez, J. I.; Israelian, G.; Delgado-Mena, E.; Santos, N. C.; Sousa, S.; Neves, V.; Udry, S.

2010-01-01

We present a fully differential chemical abundance analysis using very high resolution (λ/δλ ∼> 85, 000) and very high signal-to-noise (S/N ∼800 on average) HARPS and UVES spectra of 7 solar twins and 95 solar analogs, of which 24 are planet hosts and 71 are stars without detected planets. The whole sample of solar analogs provides very accurate Galactic chemical evolution trends in the metallicity range -0.3 < [Fe/H] < 0.5. Solar twins with and without planets show similar mean abundance ratios. We have also analyzed a sub-sample of 28 solar analogs, 14 planet hosts, and 14 stars without known planets, with spectra at S/N ∼850 on average, in the metallicity range 0.14 < [Fe/H] < 0.36, and find the same abundance pattern for both samples of stars with and without planets. This result does not depend on either the planet mass, from 7 Earth masses to 17.4 Jupiter masses, or the orbital period of the planets, from 3 to 4300 days. In addition, we have derived the slope of the abundance ratios as a function of the condensation temperature for each star and again find similar distributions of the slopes for both stars with and without planets. In particular, the peaks of these two distributions are placed at a similar value but with the opposite sign to that expected from a possible signature of terrestrial planets. In particular, two of the planetary systems in this sample, each of them containing a super-Earth-like planet, show slope values very close to these peaks, which may suggest that these abundance patterns are not related to the presence of terrestrial planets.

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.

Systematic Search for Rings around Kepler Planet Candidates: Constraints on Ring Size and Occurrence Rate

Science.gov (United States)

Aizawa, Masataka; Masuda, Kento; Kawahara, Hajime; Suto, Yasushi

2018-05-01

We perform a systematic search for rings around 168 Kepler planet candidates with sufficient signal-to-noise ratios that are selected from all of the short-cadence data. We fit ringed and ringless models to their light curves and compare the fitting results to search for the signatures of planetary rings. First, we identify 29 tentative systems, for which the ringed models exhibit statistically significant improvement over the ringless models. The light curves of those systems are individually examined, but we are not able to identify any candidate that indicates evidence for rings. In turn, we find several mechanisms of false positives that would produce ringlike signals, and the null detection enables us to place upper limits on the size of the rings. Furthermore, assuming the tidal alignment between axes of the planetary rings and orbits, we conclude that the occurrence rate of rings larger than twice the planetary radius is less than 15%. Even though the majority of our targets are short-period planets, our null detection provides statistical and quantitative constraints on largely uncertain theoretical models of the origin, formation, and evolution of planetary rings.

The solar neighborhood. XXXIV. A search for planets orbiting nearby M dwarfs using astrometry

International Nuclear Information System (INIS)

Lurie, John C.; Henry, Todd J.; Ianna, Philip A.; Jao, Wei-Chun; Quinn, Samuel N.; Winters, Jennifer G.; Koerner, David W.; Riedel, Adric R.; Subasavage, John P.

2014-01-01

Astrometric measurements are presented for seven nearby stars with previously detected planets: six M dwarfs (GJ 317, GJ 667C, GJ 581, GJ 849, GJ 876, and GJ 1214) and one K dwarf (BD-10 -3166). Measurements are also presented for six additional nearby M dwarfs without known planets, but which are more favorable to astrometric detections of low mass companions, as well as three binary systems for which we provide astrometric orbit solutions. Observations have baselines of 3 to 13 years, and were made as part of the RECONS long-term astrometry and photometry program at the CTIO/SMARTS 0.9 m telescope. We provide trigonometric parallaxes and proper motions for all 16 systems, and perform an extensive analysis of the astrometric residuals to determine the minimum detectable companion mass for the 12 M dwarfs not having close stellar secondaries. For the six M dwarfs with known planets, we are not sensitive to planets, but can rule out the presence of all but the least massive brown dwarfs at periods of 2–12 years. For the six more astrometrically favorable M dwarfs, we conclude that none have brown dwarf companions, and are sensitive to companions with masses as low as 1 M Jup for periods longer than two years. In particular, we conclude that Proxima Centauri has no Jovian companions at orbital periods of 2–12 years. These results complement previously published M dwarf planet occurrence rates by providing astrometrically determined upper mass limits on potential super-Jupiter companions at orbits of two years and longer. As part of a continuing survey, these results are consistent with the paucity of super-Jupiter and brown dwarf companions we find among the over 250 red dwarfs within 25 pc observed longer than five years in our astrometric program.

The solar neighborhood. XXXIV. A search for planets orbiting nearby M dwarfs using astrometry

Energy Technology Data Exchange (ETDEWEB)

Lurie, John C. [Department of Astronomy, University of Washington, Seattle, WA 98195 (United States); Henry, Todd J.; Ianna, Philip A. [RECONS Institute, Chambersburg, PA 17201 (United States); Jao, Wei-Chun; Quinn, Samuel N.; Winters, Jennifer G. [Department of Physics and Astronomy, Georgia State University, Atlanta, GA 30302 (United States); Koerner, David W. [Department of Physics and Astronomy, Northern Arizona University, Flagstaff, AZ 86011 (United States); Riedel, Adric R. [Department of Astrophysics, American Museum of Natural History, New York, NY 10034 (United States); Subasavage, John P., E-mail: lurie@uw.edu [United States Naval Observatory, Flagstaff, AZ 86001 (United States)

2014-11-01

Astrometric measurements are presented for seven nearby stars with previously detected planets: six M dwarfs (GJ 317, GJ 667C, GJ 581, GJ 849, GJ 876, and GJ 1214) and one K dwarf (BD-10 -3166). Measurements are also presented for six additional nearby M dwarfs without known planets, but which are more favorable to astrometric detections of low mass companions, as well as three binary systems for which we provide astrometric orbit solutions. Observations have baselines of 3 to 13 years, and were made as part of the RECONS long-term astrometry and photometry program at the CTIO/SMARTS 0.9 m telescope. We provide trigonometric parallaxes and proper motions for all 16 systems, and perform an extensive analysis of the astrometric residuals to determine the minimum detectable companion mass for the 12 M dwarfs not having close stellar secondaries. For the six M dwarfs with known planets, we are not sensitive to planets, but can rule out the presence of all but the least massive brown dwarfs at periods of 2–12 years. For the six more astrometrically favorable M dwarfs, we conclude that none have brown dwarf companions, and are sensitive to companions with masses as low as 1 M{sub Jup} for periods longer than two years. In particular, we conclude that Proxima Centauri has no Jovian companions at orbital periods of 2–12 years. These results complement previously published M dwarf planet occurrence rates by providing astrometrically determined upper mass limits on potential super-Jupiter companions at orbits of two years and longer. As part of a continuing survey, these results are consistent with the paucity of super-Jupiter and brown dwarf companions we find among the over 250 red dwarfs within 25 pc observed longer than five years in our astrometric program.

The DARWIN mission: Search for extra-solar planets

Science.gov (United States)

Kaltenegger, L.; Fridlund, M.

The direct detection of a planet close to its parent star is challenging because the signal detected from the parent star is between 109 and 106 times brighter than the signal of a planet in the visual and IR respectively. Future space based missions like DARWIN and TPF concentrate on the region between 6μ m to 18μ m, a region that contains the CO2, H2O, O3 spectral features of the atmosphere. The presence or absence of these spectral features would indicate similarities or differences with the atmosphere of telluric planets. The Infra Red Space Interferometer DARWIN is an integral part of ESA's Cosmic Vision 2020 plan, intended for a launch towards the middle of next decade. It is constructed around the new technique of `nulling interferometry', which exploits the wave nature of light to extinguish light from an on-axis bright object (the central star in this case), while at the same time light from a nearby source (the planet) is enhanced. An overview and update of the science of the DARWIN mission is given.

Limits on the abundance of galactic planets from 5 years of planet observations

NARCIS (Netherlands)

Albrow, MD; An, J; Beaulieu, JP; Caldwell, JAR; DePoy, DL; Dominik, M; Gaudi, BS; Gould, G; Greenhill, J; Hill, K; Kane, S; Martin, R; Menzies, J; Pel, JW; Pogge, RW; Pollard, KR; Sackett, PD; Sahu, KC; Vermaak, P; Watson, R; Williams, A

2001-01-01

We search for signatures of planets in 43 intensively monitored microlensing events that were observed between 1995 and 1999. Planets would be expected to cause a short-duration (similar to1 day) deviation on the smooth, symmetric light curve produced by a single lens. We find no such anomalies and

Four new planets around giant stars and the mass-metallicity correlation of planet-hosting stars

Science.gov (United States)

Jones, M. I.; Jenkins, J. S.; Brahm, R.; Wittenmyer, R. A.; Olivares E., F.; Melo, C. H. F.; Rojo, P.; Jordán, A.; Drass, H.; Butler, R. P.; Wang, L.

2016-05-01

Context. Exoplanet searches have revealed interesting correlations between the stellar properties and the occurrence rate of planets. In particular, different independent surveys have demonstrated that giant planets are preferentially found around metal-rich stars and that their fraction increases with the stellar mass. Aims: During the past six years we have conducted a radial velocity follow-up program of 166 giant stars to detect substellar companions and to characterize their orbital properties. Using this information, we aim to study the role of the stellar evolution in the orbital parameters of the companions and to unveil possible correlations between the stellar properties and the occurrence rate of giant planets. Methods: We took multi-epoch spectra using FEROS and CHIRON for all of our targets, from which we computed precision radial velocities and derived atmospheric and physical parameters. Additionally, velocities computed from UCLES spectra are presented here. By studying the periodic radial velocity signals, we detected the presence of several substellar companions. Results: We present four new planetary systems around the giant stars HIP 8541, HIP 74890, HIP 84056, and HIP 95124. Additionally, we study the correlation between the occurrence rate of giant planets with the stellar mass and metallicity of our targets. We find that giant planets are more frequent around metal-rich stars, reaching a peak in the detection of f = 16.7+15.5-5.9% around stars with [Fe/H] ~ 0.35 dex. Similarly, we observe a positive correlation of the planet occurrence rate with the stellar mass, between M⋆ ~ 1.0 and 2.1 M⊙, with a maximum of f = 13.0+10.1-4.2% at M⋆ = 2.1 M⊙. Conclusions: We conclude that giant planets are preferentially formed around metal-rich stars. In addition, we conclude that they are more efficiently formed around more massive stars, in the stellar mass range of ~1.0-2.1 M⊙. These observational results confirm previous findings for solar

A SEARCH FOR ADDITIONAL PLANETS IN THE NASA EPOXI OBSERVATIONS OF THE EXOPLANET SYSTEM GJ 436

International Nuclear Information System (INIS)

Ballard, Sarah; Christiansen, Jessie L.; Charbonneau, David; Holman, Matthew J.; Fabrycky, Daniel; Deming, Drake; Barry, Richard K.; Kuchner, Marc J.; Livengood, Timothy A.; Hewagama, Tilak; A'Hearn, Michael F.; Wellnitz, Dennis D.; Sunshine, Jessica M.; Hampton, Don L.; Lisse, Carey M.; Seager, Sara; Veverka, Joseph F.

2010-01-01

We present time series photometry of the M dwarf transiting exoplanet system GJ 436 obtained with the Extrasolar Planet Observation and Characterization (EPOCh) component of the NASA EPOXI mission. We conduct a search of the high-precision time series for additional planets around GJ 436, which could be revealed either directly through their photometric transits or indirectly through the variations these second planets induce on the transits of the previously known planet. In the case of GJ 436, the presence of a second planet is perhaps indicated by the residual orbital eccentricity of the known hot Neptune companion. We find no candidate transits with significance higher than our detection limit. From Monte Carlo tests of the time series, we rule out transiting planets larger than 1.5 R + interior to GJ 436b with 95% confidence and larger than 1.25 R + with 80% confidence. Assuming coplanarity of additional planets with the orbit of GJ 436b, we cannot expect that putative planets with orbital periods longer than about 3.4 days will transit. However, if such a planet were to transit, we would rule out planets larger than 2.0 R + with orbital periods less than 8.5 days with 95% confidence. We also place dynamical constraints on additional bodies in the GJ 436 system, independent of radial velocity measurements. Our analysis should serve as a useful guide for similar analyses of transiting exoplanets for which radial velocity measurements are not available, such as those discovered by the Kepler mission. From the lack of observed secular perturbations, we set upper limits on the mass of a second planet as small as 10 M + in coplanar orbits and 1 M + in non-coplanar orbits close to GJ 436b. We present refined estimates of the system parameters for GJ 436. We find P = 2.64389579 ± 0.00000080 d, R * = 0.437 ± 0.016 R sun , and R p = 3.880 ± 0.147 R + . We also report a sinusoidal modulation in the GJ 436 light curve that we attribute to star spots. This signal is

Planet Hunters 2 in the K2 Era

Science.gov (United States)

Schwamb, Megan E.; Fischer, Debra; Boyajian, Tabetha S.; Giguere, Matthew J.; Ishikawa, Sascha; Lintott, Chris; Lynn, Stuart; Schmitt, Joseph; Snyder, Chris; Wang, Ji; Barclay, Thomas

2015-01-01

Planet Hunters (http://www.planethunters.org) is an online citizen science project enlisting hundreds of thousands of people to search for planet transits in the publicly released Kepler data. Volunteers mark the locations of visible transits in a web interface, with multiple independent classifiers reviewing a randomly selected ~30-day light curve segment. In September 2014, Planet Hunters entered a new phase. The project was relaunched with a brand new online classification interface and discussion tool built using the Zooniverse's (http://www.zooniverse.org) latest technology and web platform. The website has been optimized for the rapid discovery and identification of planet candidates in the light curves from K2, the two-wheeled ecliptic plane Kepler mission. We will give an overview of the new Planet Hunters classification interface and Round 2 review system in context of the K2 data. We will present the first results from the Planet Hunters 2 search of K2 Campaigns 0 and 1 including a summary of new planet candidates.

Direct Imaging of Warm Extrasolar Planets

International Nuclear Information System (INIS)

Macintosh, B

2005-01-01

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 leads the

The hunt for Planet X

International Nuclear Information System (INIS)

Croswell, Ken.

1990-01-01

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

ASTEP South: An Antarctic Search for Transiting ExoPlanets around the celestial South pole

OpenAIRE

Crouzet , Nicolas; Guillot , Tristan; Agabi , Karim; Rivet , Jean-Pierre; Bondoux , Erick; Challita , Zalpha; Fanteï-Caujolle , Yan; Fressin , François; Mékarnia , Djamel; Schmider , François-Xavier; Valbousquet , Franck; Blazit , Alain; Bonhomme , Serge; Abe , Lyu; Daban , Jean-Baptiste

2009-01-01

ASTEP South is the first phase of the ASTEP project (Antarctic Search for Transiting ExoPlanets). The instrument is a fixed 10 cm refractor with a 4kx4k CCD camera in a thermalized box, pointing continuously a 3.88 degree x 3.88 degree field of view centered on the celestial South pole. ASTEP South became fully functional in June 2008 and obtained 1592 hours of data during the 2008 Antarctic winter. The data are of good quality but the analysis has to account for changes in the point spread f...

Direct Imaging Search for Extrasolar Planets in the Pleiades

Science.gov (United States)

Yamamoto, Kodai; Matsuo, Taro; Shibai, Hiroshi; Itoh, Yoichi; Konishi, Mihokko; Sudo, Jun; Tanii, Ryoko; Fukagawa, Misato; Sumi, Takahiro; Kudo, Tomoyuki;

Search and imperative programming

OpenAIRE

Apt, Krzysztof; Schaerf, A.

1996-01-01

textabstractWe augment the expressive power of imperative programming in order to make it a more attractive vehicle for problems that involve search.The proposed additions are limited yet powerful and are inspired by the logic programming paradigm.We illustrate their use by presenting solutions to a number of classical problems, including the straight search problem, the knapsack problem, and the 8 queens problem. These solutions are substantially simpler than their counterparts written in th...

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.

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.

Dysonian SETI as a "Shortcut" to Detecting Habitable Planets

Science.gov (United States)

Wright, J. T.

2016-12-01

The search for habitable planets is ultimately motivated by the search for inhabited planets. On Earth, the most telling signature of life is that of humanity's technology. The Search for Extraterrestrial Intelligence (SETI) is thus the "ultimate" search for habitable planets.In 1960 two seminal papers in SETI were published, providing two visions for SETI. Giuseppe Cocconi and Philip Morrison's proposed detecting deliberate radio signals ("communication SETI"), while Freeman Dyson ("artifact SETI"), proposed detecting the inevitable effects of massive energy supplies and artifacts on their surroundings. While communication SETI has now had many career-long practitioners and major efforts, artifact SETI has, until recently, not been a vibrant field of study. The launch of the Kepler and WISE satellites have greatly renewed interest in the field, however, and the recent Breakthrough Listen Initiative has provided new motivation for finding good targets for communication SETI. I will discuss the progress of the Ĝ Search for Extraterrestrial Civilizations with Large Energy Supplies, including its justification and motivation, waste heat search strategy and first results, and the framework for a search for megastructures via transit light curves. The last of these led to the identification of KIC 8462852 (a.k.a. "Tabby's Star") as a candidate ETI host. This star, discovered by Boyajian and the Zooniverse Planet Hunters, exhibits several apparently unique and so-far unexplained photometric properties, and continues to confound natural explanation.

On the Detectability of Planet X with LSST

Science.gov (United States)

Trilling, David E.; Bellm, Eric C.; Malhotra, Renu

2018-06-01

Two planetary mass objects in the far outer solar system—collectively referred to here as Planet X— have recently been hypothesized to explain the orbital distribution of distant Kuiper Belt Objects. Neither planet is thought to be exceptionally faint, but the sky locations of these putative planets are poorly constrained. Therefore, a wide area survey is needed to detect these possible planets. The Large Synoptic Survey Telescope (LSST) will carry out an unbiased, large area (around 18000 deg2), deep (limiting magnitude of individual frames of 24.5) survey (the “wide-fast-deep (WFD)” survey) of the southern sky beginning in 2022, and it will therefore be an important tool in searching for these hypothesized planets. Here, we explore the effectiveness of LSST as a search platform for these possible planets. Assuming the current baseline cadence (which includes the WFD survey plus additional coverage), we estimate that LSST will confidently detect or rule out the existence of Planet X in 61% of the entire sky. At orbital distances up to ∼75 au, Planet X could simply be found in the normal nightly moving object processing; at larger distances, it will require custom data processing. We also discuss the implications of a nondetection of Planet X in LSST data.

Search for giant planets in M 67. IV. Survey results

Science.gov (United States)

Brucalassi, A.; Koppenhoefer, J.; Saglia, R.; Pasquini, L.; Ruiz, M. T.; Bonifacio, P.; Bedin, L. R.; Libralato, M.; Biazzo, K.; Melo, C.; Lovis, C.; Randich, S.

2017-07-01

Context. We present the results of a seven-year-long radial velocity survey of a sample of 88 main-sequence and evolved stars to reveal signatures of Jupiter-mass planets in the solar-age and solar-metallicity open cluster M 67. Aims: We aim at studying the frequency of giant planets in this cluster with respect to the field stars. In addition, our sample is also ideal to perform a long-term study to compare the chemical composition of stars with and without giant planets in detail. Methods: We analyzed precise radial velocity (RV) measurements obtained with the HARPS spectrograph at the European Southern Observatory (La Silla), the SOPHIE spectrograph at the Observatoire de Haute-Provence (France), the HRS spectrograph at the Hobby Eberly Telescope (Texas), and the HARPS-N spectrograph at the Telescopio Nazionale Galileo (La Palma). Additional RV data come from the CORALIE spectrograph at the Euler Swiss Telescope (La Silla). We conducted Monte Carlo simulations to estimate the occurrence rate of giant planets in our radial velocity survey. We considered orbital periods between 1.0 day and 1000 days and planet masses between 0.2 MJ and 10.0 MJ. We used a measure of the observational detection efficiency to determine the frequency of planets for each star. Results: All the planets previously announced in this RV campaign with their properties are summarized here: 3 hot Jupiters around the main-sequence stars YBP1194, YBP1514, and YBP401, and 1 giant planet around the evolved star S364. Two additional planet candidates around the stars YBP778 and S978 are also analyzed in the present work. We discuss stars that exhibit large RV variability or trends individually. For 2 additional stars, long-term trends are compatible with new binary candidates or substellar objects, which increases the total number of binary candidates detected in our campaign to 14. Based on the Doppler-detected planets discovered in this survey, we find an occurrence of giant planets of 18

The search for life on Earth and other planets.

Science.gov (United States)

Gross, Michael

2012-04-10

As the NASA rover Curiosity approaches Mars on its quest to look for signs of past or present life there and sophisticated instruments like the space telescopes Kepler and CoRoT keep discovering additional, more Earth-like planets orbiting distant stars, science faces the question of how to spot life on other planets. Even here on Earth biotopes remain to be discovered and explored.

FORMATION, SURVIVAL, AND DETECTABILITY OF PLANETS BEYOND 100 AU

International Nuclear Information System (INIS)

Veras, Dimitri; Crepp, Justin R.; Ford, Eric B.

2009-01-01

Direct imaging searches have begun to detect planetary and brown dwarf companions and to place constraints on the presence of giant planets at large separations from their host star. This work helps to motivate such planet searches by predicting a population of young giant planets that could be detectable by direct imaging campaigns. Both the classical core accretion and the gravitational instability model for planet formation are hard pressed to form long-period planets in situ. Here, we show that dynamical instabilities among planetary systems that originally formed multiple giant planets much closer to the host star could produce a population of giant planets at large (∼ 10 2 -10 5 AU) separations. We estimate the limits within which these planets may survive, quantify the efficiency of gravitational scattering into both stable and unstable wide orbits, and demonstrate that population analyses must take into account the age of the system. We predict that planet scattering creates detectable giant planets on wide orbits that decreases in number on timescales of ∼ 10 Myr. We demonstrate that several members of such populations should be detectable with current technology, quantify the prospects for future instruments, and suggest how they could place interesting constraints on planet formation models.

Influence of stellar multiplicity on planet formation. I. Evidence of suppressed planet formation due to stellar companions within 20 au and validation of four planets from the Kepler multiple planet candidates

International Nuclear Information System (INIS)

Wang, Ji; Fischer, Debra A.; Xie, Ji-Wei; Barclay, Thomas

2014-01-01

The planet occurrence rate for multiple stars is important in two aspects. First, almost half of stellar systems in the solar neighborhood are multiple systems. Second, the comparison of the planet occurrence rate for multiple stars to that for single stars sheds light on the influence of stellar multiplicity on planet formation and evolution. We developed a method of distinguishing planet occurrence rates for single and multiple stars. From a sample of 138 bright (K P < 13.5) Kepler multi-planet candidate systems, we compared the stellar multiplicity rate of these planet host stars to that of field stars. Using dynamical stability analyses and archival Doppler measurements, we find that the stellar multiplicity rate of planet host stars is significantly lower than field stars for semimajor axes less than 20 AU, suggesting that planet formation and evolution are suppressed by the presence of a close-in companion star at these separations. The influence of stellar multiplicity at larger separations is uncertain because of search incompleteness due to a limited Doppler observation time baseline and a lack of high-resolution imaging observation. We calculated the planet confidence for the sample of multi-planet candidates and find that the planet confidences for KOI 82.01, KOI 115.01, KOI 282.01, and KOI 1781.02 are higher than 99.7% and thus validate the planetary nature of these four planet candidates. This sample of bright Kepler multi-planet candidates with refined stellar and orbital parameters, planet confidence estimation, and nearby stellar companion identification offers a well-characterized sample for future theoretical and observational study.

Possibilities for the detection of microbial life on extrasolar planets.

Science.gov (United States)

Knacke, Roger F

2003-01-01

We consider possibilities for the remote detection of microbial life on extrasolar planets. The Darwin/Terrestrial Planet Finder (TPF) telescope concepts for observations of terrestrial planets focus on indirect searches for life through the detection of atmospheric gases related to life processes. Direct detection of extraterrestrial life may also be possible through well-designed searches for microbial life forms. Satellites in Earth orbit routinely monitor colonies of terrestrial algae in oceans and lakes by analysis of reflected ocean light in the visible region of the spectrum. These remote sensing techniques suggest strategies for extrasolar searches for signatures of chlorophylls and related photosynthetic compounds associated with life. However, identification of such life-related compounds on extrasolar planets would require observations through strong, interfering absorptions and scattering radiances from the remote atmospheres and landmasses. Techniques for removal of interfering radiances have been extensively developed for remote sensing from Earth orbit. Comparable techniques would have to be developed for extrasolar planet observations also, but doing so would be challenging for a remote planet. Darwin/TPF coronagraph concepts operating in the visible seem to be best suited for searches for extrasolar microbial life forms with instruments that can be projected for the 2010-2020 decades, although resolution and signal-to-noise ratio constraints severely limit detection possibilities on terrestrial-type planets. The generation of telescopes with large apertures and extremely high spatial resolutions that will follow Darwin/TPF could offer striking possibilities for the direct detection of extrasolar microbial life.

A Moderate Redshift Supernova Search Program

Science.gov (United States)

Adams, M. T.; Wheeler, J. C.; Ward, M.; Wren, W. R.; Schmidt, B. P.

1995-12-01

We report on a recently initiated supernova (SN) search program using the McDonald Observatory 0.76m telescope and Prime Focus Camera (PFC). This SN search program takes advantage of the PFC's 42.6 x 42.6 arcmin FOV to survey moderate redshift Abell clusters in single Kron-Cousins R-band images. Our scientific goal is to discover and provide quality BVRI photometric follow-up, to R \\ +21, for a significant SNe sample at 0.03 group (Perlmutter et al 1995, ApJ, 440, L41), and the High Redshift SN Search Team (Schmidt et al 1995, Aiguiblava NATO ASI Proceedings). The McDonald SN search program includes a sample of the Abell clusters used by Lauer and Postman (1994, ApJ, 425, 418) to analyze Local Group motion. SNe discovered in these clusters contribute to the resolution of the Local Group motion controversy. We present an overview of the McDonald Observatory supernova search program, and discuss recent results.

Pan-Planets: Searching for hot Jupiters around cool dwarfs

Science.gov (United States)

Obermeier, C.; Koppenhoefer, J.; Saglia, R. P.; Henning, Th.; Bender, R.; Kodric, M.; Deacon, N.; Riffeser, A.; Burgett, W.; Chambers, K. C.; Draper, P. W.; Flewelling, H.; Hodapp, K. W.; Kaiser, N.; Kudritzki, R.-P.; Magnier, E. A.; Metcalfe, N.; Price, P. A.; Sweeney, W.; Wainscoat, R. J.; Waters, C.

2016-03-01

The Pan-Planets survey observed an area of 42 sq deg. in the galactic disk for about 165 h. The main scientific goal of the project is the detection of transiting planets around M dwarfs. We establish an efficient procedure for determining the stellar parameters Teff and log g of all sources using a method based on SED fitting, utilizing a three-dimensional dust map and proper motion information. In this way we identify more than 60 000 M dwarfs, which is by far the largest sample of low-mass stars observed in a transit survey to date. We present several planet candidates around M dwarfs and hotter stars that are currently being followed up. Using Monte Carlo simulations we calculate the detection efficiency of the Pan-Planets survey for different stellar and planetary populations. We expect to find 3.0+3.3-1.6 hot Jupiters around F, G, and K dwarfs with periods lower than 10 days based on the planet occurrence rates derived in previous surveys. For M dwarfs, the percentage of stars with a hot Jupiter is under debate. Theoretical models expect a lower occurrence rate than for larger main sequence stars. However, radial velocity surveys find upper limits of about 1% due to their small sample, while the Kepler survey finds a occurrence rate that we estimate to be at least 0.17b(+0.67-0.04) %, making it even higher than the determined fraction from OGLE-III for F, G and K stellar types, 0.14 (+0.15-0.076) %. With the large sample size of Pan-Planets, we are able to determine an occurrence rate of 0.11 (+0.37-0.02) % in case one of our candidates turns out to be a real detection. If, however, none of our candidates turn out to be true planets, we are able to put an upper limit of 0.34% with a 95% confidence on the hot Jupiter occurrence rate of M dwarfs. This limit is a significant improvement over previous estimates where the lowest limit published so far is 1.1% found in the WFCAM Transit Survey. Therefore we cannot yet confirm the theoretical prediction of a lower

New worlds on the horizon: Earth-sized planets close to other stars.

Science.gov (United States)

Gaidos, Eric; Haghighipour, Nader; Agol, Eric; Latham, David; Raymond, Sean; Rayner, John

2007-10-12

The search for habitable planets like Earth around other stars fulfills an ancient imperative to understand our origins and place in the cosmos. The past decade has seen the discovery of hundreds of planets, but nearly all are gas giants like Jupiter and Saturn. Recent advances in instrumentation and new missions are extending searches to planets the size of Earth but closer to their host stars. There are several possible ways such planets could form, and future observations will soon test those theories. Many of these planets we discover may be quite unlike Earth in their surface temperature and composition, but their study will nonetheless inform us about the process of planet formation and the frequency of Earth-like planets around other stars.

The effect of M dwarf starspot activity on low-mass planet

NARCIS (Netherlands)

Barnes, J.R.; Jeffers, S.V.; Jones, H.R.A.

2011-01-01

In light of the growing interest in searching for low mass, rocky planets, we investigate the impact of starspots on radial velocity searches for earth-mass planets in orbit about M dwarf stars. Since new surveys targeting M dwarfs will likely be carried out at infrared wavelengths, a comparison

Deep Imaging Search for Planets Forming in the TW Hya Protoplanetary Disk with the Keck/NIRC2 Vortex Coronagraph

Science.gov (United States)

Ruane, G.; Mawet, D.; Kastner, J.; Meshkat, T.; Bottom, M.; Femenía Castellá, B.; Absil, O.; Gomez Gonzalez, C.; Huby, E.; Zhu, Z.; Jenson-Clem, R.; Choquet, É.; Serabyn, E.

2017-08-01

Distinct gap features in the nearest protoplanetary disk, TW Hya (distance of 59.5 ± 0.9 pc), may be signposts of ongoing planet formation. We performed long-exposure thermal infrared coronagraphic imaging observations to search for accreting planets, especially within dust gaps previously detected in scattered light and submillimeter-wave thermal emission. Three nights of observations with the Keck/NIRC2 vortex coronagraph in L‧ (3.4-4.1 μm) did not reveal any statistically significant point sources. We thereby set strict upper limits on the masses of non-accreting planets. In the four most prominent disk gaps at 24, 41, 47, and 88 au, we obtain upper mass limits of 1.6-2.3, 1.1-1.6, 1.1-1.5, and 1.0-1.2 Jupiter masses (M J), assuming an age range of 7-10 Myr for TW Hya. These limits correspond to the contrast at 95% completeness (true positive fraction of 0.95) with a 1% chance of a false positive within 1″ of the star. We also approximate an upper limit on the product of the planet mass and planetary accretion rate of {M}{{p}}\\dot{M}≲ {10}-8 {M}{{J}}2 {{yr}}-1 implying that any putative ˜0.1 M J planet, which could be responsible for opening the 24 au gap, is presently accreting at rates insufficient to build up a Jupiter mass within TW Hya’s pre-main-sequence lifetime.

Formation of S-type planets in close binaries: scattering induced tidal capture of circumbinary planets

Science.gov (United States)

Gong, Yan-Xiang; Ji, Jianghui

2018-05-01

Although several S-type and P-type planets in binary systems were discovered in past years, S-type planets have not yet been found in close binaries with an orbital separation not more than 5 au. Recent studies suggest that S-type planets in close binaries may be detected through high-accuracy observations. However, nowadays planet formation theories imply that it is difficult for S-type planets in close binaries systems to form in situ. In this work, we extensively perform numerical simulations to explore scenarios of planet-planet scattering among circumbinary planets and subsequent tidal capture in various binary configurations, to examine whether the mechanism can play a part in producing such kind of planets. Our results show that this mechanism is robust. The maximum capture probability is ˜10%, which can be comparable to the tidal capture probability of hot Jupiters in single star systems. The capture probability is related to binary configurations, where a smaller eccentricity or a low mass ratio of the binary will lead to a larger probability of capture, and vice versa. Furthermore, we find that S-type planets with retrograde orbits can be naturally produced via capture process. These planets on retrograde orbits can help us distinguish in situ formation and post-capture origin for S-type planet in close binaries systems. The forthcoming missions (PLATO) will provide the opportunity and feasibility to detect such planets. Our work provides several suggestions for selecting target binaries in search for S-type planets in the near future.

A Search for Giant Planet Companions to T Tauri Stars

Science.gov (United States)

2012-12-20

detection – stars: pre-main sequence – techniques: radial velocities Online-only material: color figures 1. INTRODUCTION The discovery of over 760...exoplanets8 in the past twenty years has revealed that planetary systems are common and diverse. Pulsar planets (Wolszczan 1994), hot Jupiters (Mayor... discoveries , the processes underlying planet formation remain unclear. Lacking direct observational inputs, theorists must deduce formation mechanisms from

Search and imperative programming

NARCIS (Netherlands)

K.R. Apt (Krzysztof); A. Schaerf

1996-01-01

textabstractWe augment the expressive power of imperative programming in order to make it a more attractive vehicle for problems that involve search.The proposed additions are limited yet powerful and are inspired by the logic programming paradigm.We illustrate their use by presenting solutions to a

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

Studying the Water Cycle in an Environmental Context: The "Blue Planet" Program.

Science.gov (United States)

Ben-zvi-assaraf, Orit; Orion, Nir

The Blue Planet program aims to develop an understanding of and insight into the environment among students by introducing environmental problems such as pollution. This paper presents a study investigating junior high school students' previous knowledge and understanding of environmental issues and perceptions on the nature of the water cycle.…

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.

Discovering transits of HD 209458-b type planets with Hipparcos and FAME photometry

Science.gov (United States)

Castellano, Timothy Paul

The motivation and prospects for success of a search for transits of short-period extrasolar planets of late-type main sequence stars in the Hipparcos satellite photometry archive is outlined. Recent extrasolar planet discoveries by the radial velocity (RV) method reveal that 1 in 20 spectral type F, G and K dwarfs possess short-period planets. Careful consideration of the transit detection probability as a function of stellar spectral type and planet orbit size results in the expectation that 6 to 24 transiting planets may be found among the 118,204 Hipparcos catalog stars. A search algorithm based on the known properties of the single known transiting extrasolar planet HD 209458-b was applied to carefully- selected samples of stars. The results of these searches and simulations of the detection efficiency for idealized transits are presented. Statistical and catalog-based methods for discriminating transits from intrinsic stellar variability and eclipses due to stellar companions are developed and described. Candidate lists that are the results of these searches are presented. Each candidate is placed in a color magnitude diagram based on Hipparcos derived distances and absolute magnitudes in order to clearly identify evolved stars. The effect of Lutz-Kelker bias on this main sequence membership determination is discussed in an Appendix. A Hipparcos-photometry-based intrinsic stellar variability determination is performed and compared to ground-based measurements. It is shown that intrinsic stellar variability of late-type main sequence stars is not a major concern for extrasolar jovian planet transit searches. The prospects for transit detection by the higher precision measurements of several hundred thousand main sequence stars to be made by the upcoming Full Sky Astrometric Explorer (FAME) satellite are similarly explored. A novel method for directly determining the mass of a transiting planet's parent star from timing measurements is introduced briefly in an

HIDING IN THE SHADOWS: SEARCHING FOR PLANETS IN PRE-TRANSITIONAL AND TRANSITIONAL DISKS

International Nuclear Information System (INIS)

Dobinson, Jack; Leinhardt, Zoë M.; Dodson-Robinson, Sarah E.; Teanby, Nick A.

2013-01-01

Transitional and pre-transitional disks can be explained by a number of mechanisms. This work aims to find a single observationally detectable marker that would imply a planetary origin for the gap and, therefore, indirectly indicate the presence of a young planet. N-body simulations were conducted to investigate the effect of an embedded planet of one Jupiter mass on the production of instantaneous collisional dust derived from a background planetesimal disk. Our new model allows us to predict the dust distribution and resulting observable markers with greater accuracy than previous works. Dynamical influences from a planet on a circular orbit are shown to enhance dust production in the disk interior and exterior to the planet orbit, while removing planetesimals from the orbit itself, creating a clearly defined gap. In the case of an eccentric planet, the gap opened by the planet is not as clear as the circular case, but there is a detectable asymmetry in the dust disk

Humans Need Not Apply: Robotization of Kepler Planet Candidate Vetting

Science.gov (United States)

Coughlin, Jeffrey; Mullally, Fergal; Thompson, Susan E.; Kepler Team

2015-01-01

Until now, the vast majority of Kepler planet candidate vetting has been performed by a dedicated team of humans. While human expertise has been invaluable in understanding the nuances of Kepler data, human vetting is very time-consuming and can be inconsistent. Over 20,000 threshold crossing events have been produced by the latest pipeline run on all 17 quarters of Kepler mission data, and many more artificial planet transits have been injected to estimate completeness. Given these large numbers, human vetting is no longer feasible on a reasonable time-scale, and would be difficult to characterize. We have created automated vetting programs known as "robovetters" that are specifically designed to mimic the decision-making process employed by the humans. They analyze both the light curve and pixel-level data in order to produce specific reasons for identifying false positives. We present benchmark tests on the Q1-Q16 Kepler planet catalog, which was vetted by humans, and present preliminary robovetter results based on a recent transit-search of the newly reprocessed Q1-Q17 data set.

THE QUASIPERIODIC AUTOMATED TRANSIT SEARCH ALGORITHM

International Nuclear Information System (INIS)

Carter, Joshua A.; Agol, Eric

2013-01-01

We present a new algorithm for detecting transiting extrasolar planets in time-series photometry. The Quasiperiodic Automated Transit Search (QATS) algorithm relaxes the usual assumption of strictly periodic transits by permitting a variable, but bounded, interval between successive transits. We show that this method is capable of detecting transiting planets with significant transit timing variations without any loss of significance— s mearing — as would be incurred with traditional algorithms; however, this is at the cost of a slightly increased stochastic background. The approximate times of transit are standard products of the QATS search. Despite the increased flexibility, we show that QATS has a run-time complexity that is comparable to traditional search codes and is comparably easy to implement. QATS is applicable to data having a nearly uninterrupted, uniform cadence and is therefore well suited to the modern class of space-based transit searches (e.g., Kepler, CoRoT). Applications of QATS include transiting planets in dynamically active multi-planet systems and transiting planets in stellar binary systems.

The Search for Another Earth

Indian Academy of Sciences (India)

IAS Admin

for our very existence in the universe. Although the search for ... confirmed planet orbiting around the solar-type star 51 Pegasi. ... for planets outside the solar system, termed as extraso- lar planets or ..... another Indian origin astrophysicist.

Giant Planets: Good Neighbors for Habitable Worlds?

Science.gov (United States)

Georgakarakos, Nikolaos; Eggl, Siegfried; Dobbs-Dixon, Ian

2018-04-01

The presence of giant planets influences potentially habitable worlds in numerous ways. Massive celestial neighbors can facilitate the formation of planetary cores and modify the influx of asteroids and comets toward Earth analogs later on. Furthermore, giant planets can indirectly change the climate of terrestrial worlds by gravitationally altering their orbits. Investigating 147 well-characterized exoplanetary systems known to date that host a main-sequence star and a giant planet, we show that the presence of “giant neighbors” can reduce a terrestrial planet’s chances to remain habitable, even if both planets have stable orbits. In a small fraction of systems, however, giant planets slightly increase the extent of habitable zones provided that the terrestrial world has a high climate inertia. In providing constraints on where giant planets cease to affect the habitable zone size in a detrimental fashion, we identify prime targets in the search for habitable worlds.

Possible influence of cosmic ray Cerenkov photons on infrared interferometric search for non-solar planets

International Nuclear Information System (INIS)

Lerche, I.

1980-01-01

It is shown that the pervasive cosmic-ray protons in the vicinity of the Earth would produce infrared photons by Cerenkov radiation in the material walls, and mirrors, of an orbiting infrared interferometer designed to search for non-solar planets. The flux of such photons is at least comparable to the zodiacal infrared background radiation. It is found that for the worst possible conditions a minimum time of about six weeks is indicated for planetary detection using a fourth-harmonic noise analysis. It is suggested that direct laboratory measurement of a simulated cosmic-ray-induced Cerenkov flux be undertaken to settle the question of the background contaminant produced by this effect. (Auth.)

The Dependence of Signal-To-Noise Ratio (S/N) Between Star Brightness and Background on the Filter Used in Images Taken by the Vulcan Photometric Planet Search Camera

Science.gov (United States)

Mena-Werth, Jose

1998-01-01

The Vulcan Photometric Planet Search is the ground-based counterpart of Kepler Mission Proposal. The Kepler Proposal calls for the launch of telescope to look intently at a small patch of sky for four year. The mission is designed to look for extra-solar planets that transit sun-like stars. The Kepler Mission should be able to detect Earth-size planets. This goal requires an instrument and software capable of detecting photometric changes of several parts per hundred thousand in the flux of a star. The goal also requires the continuous monitoring of about a hundred thousand stars. The Kepler Mission is a NASA Discovery Class proposal similar in cost to the Lunar Prospector. The Vulcan Search is also a NASA project but based at Lick Observatory. A small wide-field telescope monitors various star fields successively during the year. Dozens of images, each containing tens of thousands of stars, are taken any night that weather permits. The images are then monitored for photometric changes of the order of one part in a thousand. These changes would reveal the transit of an inner-orbit Jupiter-size planet similar to those discovered recently in spectroscopic searches. In order to achieve a one part in one thousand photometric precision even the choice of a filter used in taking an exposure can be critical. The ultimate purpose of an filter is to increase the signal-to-noise ratio (S/N) of one's observation. Ideally, filters reduce the sky glow cause by street lights and, thereby, make the star images more distinct. The higher the S/N, the higher is the chance to observe a transit signal that indicates the presence of a new planet. It is, therefore, important to select the filter that maximizes the S/N.

34 CFR 643.1 - What is the Talent Search program?

Science.gov (United States)

2010-07-01

... 34 Education 3 2010-07-01 2010-07-01 false What is the Talent Search program? 643.1 Section 643.1... EDUCATION, DEPARTMENT OF EDUCATION TALENT SEARCH General § 643.1 What is the Talent Search program? The Talent Search program provides grants for projects designed to— (a) Identify qualified youths with...

Friends of hot Jupiters. I. A radial velocity search for massive, long-period companions to close-in gas giant planets

Energy Technology Data Exchange (ETDEWEB)

Knutson, Heather A.; Ngo, Henry; Johnson, John Asher [Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA 91125 (United States); Fulton, Benjamin J.; Howard, Andrew W. [Institute for Astronomy, University of Hawaii at Manoa, Honolulu, HI (United States); Montet, Benjamin T.; Kao, Melodie; Hinkley, Sasha; Morton, Timothy D.; Muirhead, Philip S. [Cahill Center for Astronomy and Astrophysics, California Institute of Technology, 1200 East California Boulevard, MC 249-17, Pasadena, CA 91125 (United States); Crepp, Justin R. [Department of Physics, University of Notre Dame, Notre Dame, IN (United States); Bakos, Gaspar Á. [Department of Astrophysical Sciences, Princeton University, Princeton, NJ (United States); Batygin, Konstantin, E-mail: hknutson@caltech.edu [Harvard-Smithsonian Center for Astrophysics, Cambridge, MA (United States)

2014-04-20

In this paper we search for distant massive companions to known transiting gas giant planets that may have influenced the dynamical evolution of these systems. We present new radial velocity observations for a sample of 51 planets obtained using the Keck HIRES instrument, and find statistically significant accelerations in fifteen systems. Six of these systems have no previously reported accelerations in the published literature: HAT-P-10, HAT-P-22, HAT-P-29, HAT-P-32, WASP-10, and XO-2. We combine our radial velocity fits with Keck NIRC2 adaptive optics (AO) imaging data to place constraints on the allowed masses and orbital periods of the companions responsible for the detected accelerations. The estimated masses of the companions range between 1-500 M {sub Jup}, with orbital semi-major axes typically between 1-75 AU. A significant majority of the companions detected by our survey are constrained to have minimum masses comparable to or larger than those of the transiting planets in these systems, making them candidates for influencing the orbital evolution of the inner gas giant. We estimate a total occurrence rate of 51% ± 10% for companions with masses between 1-13 M {sub Jup} and orbital semi-major axes between 1-20 AU in our sample. We find no statistically significant difference between the frequency of companions to transiting planets with misaligned or eccentric orbits and those with well-aligned, circular orbits. We combine our expanded sample of radial velocity measurements with constraints from transit and secondary eclipse observations to provide improved measurements of the physical and orbital characteristics of all of the planets included in our survey.

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.

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).

The Gemini Planet Imager Exoplanet Survey

Science.gov (United States)

Macintosh, Bruce

accurate and calibrated recovery of exoplanet spectra. We will produce a complete archive of all reduced GPI data products (supplementing the existing Gemini archive of raw data) for use by our collaboration, and release that archive to the public on an 18-month cycle. Most importantly, we will execute the GPI observations, initially through classical telescope visits, transitioning to remote and queue modes as our techniques are refined. As the first direct-imaging planet search with statistical depth comparable to Doppler planet detection and the first to probe into the snow line, the GPI Exoplanet Survey will provide strong constraints on paradigms for planet formation, completing the picture of the giant planet distribution throughout other solar systems, and also illuminating its evolution with stellar age and mass. We will deliver a catalog of detected exoplanets— the principal legacy of this campaign—released for follow-up by the astronomical community within 18 months of observation, as well as searchable archive of fully reduced images and detection limits for all stars surveyed. For each detected planet, we will produce estimated effective temperatures, luminosities, and semi-major axes: for a subset, high-SNR fiducial spectra, orbital eccentricities, and dynamical characterization through polarimetric imaging of attendant debris disks. GPI will complete final acceptance testing this month (May 2013) and is now ready to ship to Chile for first light in September 2013. The GPI survey will provide the best-yet 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.

Optimal Target Stars in the Search for Life

Science.gov (United States)

Lingam, Manasvi; Loeb, Abraham

2018-04-01

The selection of optimal targets in the search for life represents a highly important strategic issue. In this Letter, we evaluate the benefits of searching for life around a potentially habitable planet orbiting a star of arbitrary mass relative to a similar planet around a Sun-like star. If recent physical arguments implying that the habitability of planets orbiting low-mass stars is selectively suppressed are correct, we find that planets around solar-type stars may represent the optimal targets.

Kepler Data Validation I: Architecture, Diagnostic Tests, and Data Products for Vetting Transiting Planet Candidates

Science.gov (United States)

Twicken, Joseph D.; Catanzarite, Joseph H.; Clarke, Bruce D.; Giroud, Forrest; Jenkins, Jon M.; Klaus, Todd C.; Li, Jie; McCauliff, Sean D.; Seader, Shawn E.; Tennenbaum, Peter;

Kepler Data Validation I—Architecture, Diagnostic Tests, and Data Products for Vetting Transiting Planet Candidates

Science.gov (United States)

Twicken, Joseph D.; Catanzarite, Joseph H.; Clarke, Bruce D.; Girouard, Forrest; Jenkins, Jon M.; Klaus, Todd C.; Li, Jie; McCauliff, Sean D.; Seader, Shawn E.; Tenenbaum, Peter; Wohler, Bill; Bryson, Stephen T.; Burke, Christopher J.; Caldwell, Douglas A.; Haas, Michael R.; Henze, Christopher E.; Sanderfer, Dwight T.

2018-06-01

The Kepler Mission was designed to identify and characterize transiting planets in the Kepler Field of View and to determine their occurrence rates. Emphasis was placed on identification of Earth-size planets orbiting in the Habitable Zone of their host stars. Science data were acquired for a period of four years. Long-cadence data with 29.4 min sampling were obtained for ∼200,000 individual stellar targets in at least one observing quarter in the primary Kepler Mission. Light curves for target stars are extracted in the Kepler Science Data Processing Pipeline, and are searched for transiting planet signatures. A Threshold Crossing Event is generated in the transit search for targets where the transit detection threshold is exceeded and transit consistency checks are satisfied. These targets are subjected to further scrutiny in the Data Validation (DV) component of the Pipeline. Transiting planet candidates are characterized in DV, and light curves are searched for additional planets after transit signatures are modeled and removed. A suite of diagnostic tests is performed on all candidates to aid in discrimination between genuine transiting planets and instrumental or astrophysical false positives. Data products are generated per target and planet candidate to document and display transiting planet model fit and diagnostic test results. These products are exported to the Exoplanet Archive at the NASA Exoplanet Science Institute, and are available to the community. We describe the DV architecture and diagnostic tests, and provide a brief overview of the data products. Transiting planet modeling and the search for multiple planets on individual targets are described in a companion paper. The final revision of the Kepler Pipeline code base is available to the general public through GitHub. The Kepler Pipeline has also been modified to support the Transiting Exoplanet Survey Satellite (TESS) Mission which is expected to commence in 2018.

Undergraduate Planet Hunters: Tools and Results

Science.gov (United States)

Buzasi, Derek L.; Carboneau, Lindsey; Ferrell, Laura; Green, Gilbert; Kaiser, Maya; Kreke, Kira; Lundy, Samantha; Merritt, William; Passino, Matlin; Paxton, Harrison; Podaril, Alexandria; Stansfield, Alexis

2018-06-01

One student "Honors Experience" option at Florida Gulf Coast University is a research experience, and we have developed a "Planet Hunters" course to provide an astronomical research track that satisfies that requirement. Students spend the first semester learning astronomical background and exoplanet detection techniques, while the second semester is primarily devoted to planet searches in K2 data using student-oriented software tools developed specifically for the task. In this poster, we illustrate those tools and show results obtained by class participants during this years experience.

OPUS - Outer Planets Unified Search with Enhanced Surface Geometry Parameters - Not Just for Rings

Science.gov (United States)

Gordon, Mitchell; Showalter, Mark Robert; Ballard, Lisa; Tiscareno, Matthew S.; Heather, Neil

2016-10-01

In recent years, with the massive influx of data into the PDS from a wide array of missions and instruments, finding the precise data you need has been an ongoing challenge. For remote sensing data obtained from Jupiter to Pluto, that challenge is being addressed by the Outer Planets Unified Search, more commonly known as OPUS.OPUS is a powerful search tool available at the PDS Ring-Moon Systems Node (RMS) - formerly the PDS Rings Node. While OPUS was originally designed with ring data in mind, its capabilities have been extended to include all of the targets within an instrument's field of view. OPUS provides preview images of search results, and produces a zip file for easy download of selected products, including a table of user specified metadata. For Cassini ISS and Voyager ISS we have generated and include calibrated versions of every image.Currently OPUS supports data returned by Cassini ISS, UVIS, VIMS, and CIRS (Saturn data through June 2010), New Horizons Jupiter LORRI, Galileo SSI, Voyager ISS and IRIS, and Hubble (ACS, WFC3 and WFPC2).At the RMS Node, we have developed and incorporated into OPUS detailed geometric metadata, based on the most recent SPICE kernels, for all of the bodies in the Cassini Saturn observations. This extensive set of geometric metadata is unique to the RMS Node and enables search constraints such as latitudes and longitudes (Saturn, Titan, and icy satellites), viewing and illumination geometry (phase, incidence and emission angles), and distances and resolution.Our near term plans include adding the full set of Cassini CIRS Saturn data (with enhanced geometry), New Horizons MVIC Jupiter encounter images, New Horizons LORRI and MVIC Pluto data, HST STIS observations, and Cassini and Voyager ring occultations. We also plan to develop enhanced geometric metadata for the New Horizons LORRI and MVIC instruments for both the Jupiter and the Pluto encounters.OPUS: http://pds-rings.seti.org/search/

THE ANGLO-AUSTRALIAN PLANET SEARCH. XXI. A GAS-GIANT PLANET IN A ONE YEAR ORBIT AND THE HABITABILITY OF GAS-GIANT SATELLITES

International Nuclear Information System (INIS)

Tinney, C. G.; Wittenmyer, Robert A.; Bailey, Jeremy A.; Horner, J.; Butler, R. Paul; Jones, Hugh R. A.; O'Toole, Simon J.; Carter, Brad D.

2011-01-01

We have detected the Doppler signature of a gas-giant exoplanet orbiting the star HD 38283, in an eccentric orbit with a period of almost exactly one year (P = 363.2 ± 1.6 d, m sin i = 0.34 ± 0.02 M Jup , e = 0.41 ± 0.16). The detection of a planet with period very close to one year critically relied on year-round observation of this circumpolar star. Discovering a planet in a 1 AU orbit around a G dwarf star has prompted us to look more closely at the question of the habitability of the satellites of such planets. Regular satellites orbit all the giant planets in our solar system, suggesting that their formation is a natural by-product of the planet formation process. There is no reason for exomoon formation not to be similarly likely in exoplanetary systems. Moreover, our current understanding of that formation process does not preclude satellite formation in systems where gas giants undergo migration from their formation locations into the terrestrial planet habitable zone. Indeed, regular satellite formation and Type II migration are both linked to the clearing of a gap in the protoplanetary disk by a planet, and so may be inextricably linked. Migration would also multiply the chances of capturing both irregular satellites and Trojan companions sufficiently massive to be habitable. The habitability of such exomoons and exo-Trojans will critically depend on their mass, whether or not they host a magnetosphere, and (for the exomoon case) their orbital radius around the host exoplanet.

Prevalence of Earth-size planets orbiting Sun-like stars

OpenAIRE

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 (1-2 Earth-radii) and receive comparable levels of stellar energy to that of Earth (within a factor of four). We account...

Full exploration of the giant planet population around β Pictoris

Science.gov (United States)

Lagrange, A.-M.; Keppler, M.; Meunier, N.; Lannier, J.; Beust, H.; Milli, J.; Bonnavita, M.; Bonnefoy, M.; Borgniet, S.; Chauvin, G.; Delorme, P.; Galland, F.; Iglesias, D.; Kiefer, F.; Messina, S.; Vidal-Madjar, A.; Wilson, P. A.

2018-05-01

Context. The search for extrasolar planets has been limited so far to close orbit (typ. ≤5 au) planets around mature solar-type stars on the one hand, and to planets on wide orbits (≥10 au) around young stars on the other hand. To get a better view of the full giant planet population, we have started a survey to search for giant planets around a sample of carefully selected young stars. Aims: This paper aims at exploring the giant planet population around one of our targets, β Pictoris, over a wide range of separations. With a disk and a planet already known, the β Pictoris system is indeed a very precious system for studies of planetary formation and evolution, as well as of planet-disk interactions. Methods: We analyse more than 2000 HARPS high-resolution spectra taken over 13 years as well as NaCo images recorded between 2003 and 2016. We combine these data to compute the detection probabilities of planets throughout the disk, from a fraction of au to a few dozen au. Results: We exclude the presence of planets more massive than 3 MJup closer than 1 au and further than 10 au, with a 90% probability. 15+ MJup companions are excluded throughout the disk except between 3 and 5 au with a 90% probability. In this region, we exclude companions with masses larger than 18 (resp. 30) MJup with probabilities of 60 (resp. 90) %. Based on data obtained with the ESO3.6 m/HARPS spectrograph at La Silla, and with NaCO on the VLT.The RV data are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/612/A108

Extrasolar binary planets. I. Formation by tidal capture during planet-planet scattering

International Nuclear Information System (INIS)

Ochiai, H.; Nagasawa, M.; Ida, S.

2014-01-01

We have investigated (1) the formation of gravitationally bounded pairs of gas-giant planets (which we call 'binary planets') from capturing each other through planet-planet dynamical tide during their close encounters and (2) the subsequent long-term orbital evolution due to planet-planet and planet-star quasi-static tides. For the initial evolution in phase 1, we carried out N-body simulations of the systems consisting of three Jupiter-mass planets taking into account the dynamical tide. The formation rate of the binary planets is as much as 10% of the systems that undergo orbital crossing, and this fraction is almost independent of the initial stellarcentric semimajor axes of the planets, while ejection and merging rates sensitively depend on the semimajor axes. As a result of circularization by the planet-planet dynamical tide, typical binary separations are a few times the sum of the physical radii of the planets. After the orbital circularization, the evolution of the binary system is governed by long-term quasi-static tide. We analytically calculated the quasi-static tidal evolution in phase 2. The binary planets first enter the spin-orbit synchronous state by the planet-planet tide. The planet-star tide removes angular momentum of the binary motion, eventually resulting in a collision between the planets. However, we found that the binary planets survive the tidal decay for the main-sequence lifetime of solar-type stars (∼10 Gyr), if the binary planets are beyond ∼0.3 AU from the central stars. These results suggest that the binary planets can be detected by transit observations at ≳ 0.3 AU.

Imaging Planet Formation Inside the Diffraction Limit

Science.gov (United States)

Sallum, Stephanie Elise

For decades, astronomers have used observations of mature planetary systems to constrain planet formation theories, beginning with our own solar system and now the thousands of known exoplanets. Recent advances in instrumentation have given us a direct view of some steps in the planet formation process, such as large-scale protostar and protoplanetary disk features and evolution. However, understanding the details of how planets accrete and interact with their environment requires direct observations of protoplanets themselves. Transition disks, protoplanetary disks with inner clearings that may be caused by forming planets, are the best targets for these studies. Their large distances, compared to the stars normally targeted for direct imaging of exoplanets, make protoplanet detection difficult and necessitate novel imaging techniques. In this dissertation, I describe the results of using non-redundant masking (NRM) to search for forming planets in transition disk clearings. I first present a data reduction pipeline that I wrote to this end, using example datasets and simulations to demonstrate reduction and imaging optimizations. I discuss two transition disk NRM case studies: T Cha and LkCa 15. In the case of T Cha, while we detect significant asymmetries, the data cannot be explained by orbiting companions. The fluxes and orbital motion of the LkCa 15 companion signals, however, can be naturally explained by protoplanets in the disk clearing. I use these datasets and simulated observations to illustrate the effects of scattered light from transition disk material on NRM protoplanet searches. I then demonstrate the utility of the dual-aperture Large Binocular Telescope Interferometer's NRM mode on the bright B[e] star MWC 349A. I discuss the implications of this work for planet formation studies as well as future prospects for NRM and related techniques on next generation instruments.

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.

Stars and Planets: A New Set of Middle School Activities

Science.gov (United States)

Urquhart, M. L.

2002-01-01

A set of lesson plans for grades 6-8 which deal with the sizes and distances of stars and planets using a scale factor of 1 to 10 billion, the life cycle of stars, and the search for planets beyond the solar system. Additional information is contained in the original extended abstract.

Deep Space Detectives: Searching for Planets Suitable for Life

Science.gov (United States)

Pallant, Amy; Damelin, Daniel; Pryputniewicz, Sarah

2013-01-01

This article describes the High-Adventure Science curriculum unit "Is There Life in Space?" This free online investigation, developed by The Concord Consortium, helps students see how scientists use modern tools to locate planets around distant stars and explore the probability of finding extraterrestrial life. This innovative curriculum…

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.

The HARPS search for southern extra-solar planets . XXXII. New multi-planet systems in the HARPS volume limited sample: a super-Earth and a Neptune in the habitable zone

Science.gov (United States)

Lo Curto, G.; Mayor, M.; Benz, W.; Bouchy, F.; Hébrard, G.; Lovis, C.; Moutou, C.; Naef, D.; Pepe, F.; Queloz, D.; Santos, N. C.; Segransan, D.; Udry, S.

2013-03-01

The vast diversity of planetary systems detected to date is defying our capability of understanding their formation and evolution. Well-defined volume-limited surveys are the best tool at our disposal to tackle the problem, via the acquisition of robust statistics of the orbital elements. We are using the HARPS spectrograph to conduct our survey of ≈850 nearby solar-type stars, and in the course of the past nine years we have monitored the radial velocity of HD 103774, HD 109271, and BD-061339. In this work we present the detection of five planets orbiting these stars, with msin (i) between 0.6 and 7 Neptune masses, four of which are in two multiple systems, comprising one super-Earth and one planet within the habitable zone of a late-type dwarf. Although for strategic reasons we chose efficiency over precision in this survey, we have the capability to detect planets down to the Neptune and super-Earth mass range as well as multiple systems, provided that enough data points are made available. Based on observations made with the HARPS instrument on the ESO 3.6 m telescope at La Silla (Chile), under the GTO program ID 072.C-0488 and the regular programs: 085.C-0019, 087.C-0831 and 089.C-0732. RV data 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/A59

The occurrence of planets and other substellar bodies around white dwarfs using K2

Science.gov (United States)

van Sluijs, L.; Van Eylen, V.

2018-03-01

The majority of stars both host planetary systems and evolve into a white dwarf (WD). To understand their post-main-sequence planetary system evolution, we present a search for transiting/eclipsing planets and other substellar bodies (SBs) around WDs using a sample of 1148 WDs observed by K2. Using transit injections, we estimate the completeness of our search. We place constraints on the occurrence of planets and SBs around WDs as a function of planet radius and orbital period. For short-period (P sized to 1.5 R⊕, these are the strongest constraints known to date. We further constrain the occurrence of hot Jupiters ( Earth-sized planets ( < 28 per cent), and disintegrating short-period planets ( ˜ 12 per cent). We blindly recovered all previously known eclipsing objects, providing confidence in our analysis, and make all light curves publicly available.

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.

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

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.

Validation and Initial Characterization of the Long-period Planet Kepler-1654 b

Science.gov (United States)

Beichman, C. A.; Giles, H. A. C.; Akeson, R.; Ciardi, D.; Christiansen, J.; Isaacson, H.; Marcy, G. M.; Sinukoff, E.; Greene, T.; Fortney, J. J.; Crossfield, I.; Hu, R.; Howard, A. W.; Petigura, E. A.; Knutson, H. A.

2018-04-01

Fewer than 20 transiting Kepler planets have periods longer than one year. Our early search of the Kepler light curves revealed one such system, Kepler-1654b (originally KIC 8410697b), which shows exactly two transit events and whose second transit occurred only five days before the failure of the second of two reaction wheels brought the primary Kepler mission to an end. A number of authors have also examined light curves from the Kepler mission searching for long-period planets and identified this candidate. Starting in 2014 September, we began an observational program of imaging, reconnaissance spectroscopy, and precision radial velocity (RV) measurements that confirm with a high degree of confidence that Kepler-1654b is a bona fide transiting planet orbiting a mature G5V star (T eff = 5580 K, [Fe/H] = ‑0.08) with a semimajor axis of 2.03 au, a period of 1047.84 days, and a radius of 0.82 ± 0.02 R Jup. RV measurements using Keck’s HIRES spectrometer obtained over 2.5 years set a limit to the planet’s mass of <0.5 (3σ) M Jup. The bulk density of the planet is similar to that of Saturn or possibly lower. We assess the suitability of temperate gas giants like Kepler-1654b for transit spectroscopy with the James Webb Space Telescope, as their relatively cold equilibrium temperatures (T pl ∼ 200 K) make them interesting from the standpoint of exoplanet atmospheric physics. Unfortunately, these low temperatures also make the atmospheric scale heights small and thus transmission spectroscopy challenging. Finally, the long time between transits can make scheduling JWST observations difficult—as is the case with Kepler-1654b.

PLANET-PLANET SCATTERING IN PLANETESIMAL DISKS

International Nuclear Information System (INIS)

Raymond, Sean N.; Armitage, Philip J.; Gorelick, Noel

2009-01-01

We study the final architecture of planetary systems that evolve under the combined effects of planet-planet and planetesimal scattering. Using N-body simulations we investigate the dynamics of marginally unstable systems of gas and ice giants both in isolation and when the planets form interior to a planetesimal belt. The unstable isolated systems evolve under planet-planet scattering to yield an eccentricity distribution that matches that observed for extrasolar planets. When planetesimals are included the outcome depends upon the total mass of the planets. For M tot ∼> 1 M J the final eccentricity distribution remains broad, whereas for M tot ∼ J a combination of divergent orbital evolution and recircularization of scattered planets results in a preponderance of nearly circular final orbits. We also study the fate of marginally stable multiple planet systems in the presence of planetesimal disks, and find that for high planet masses the majority of such systems evolve into resonance. A significant fraction leads to resonant chains that are planetary analogs of Jupiter's Galilean satellites. We predict that a transition from eccentric to near-circular orbits will be observed once extrasolar planet surveys detect sub-Jovian mass planets at orbital radii of a ≅ 5-10 AU.

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

Survival of extrasolar giant planet moons in planet-planet scattering

Science.gov (United States)

CIAN HONG, YU; Lunine, Jonathan; Nicholson, Phillip; Raymond, Sean

2015-12-01

Planet-planet scattering is the best candidate mechanism for explaining the eccentricity distribution of exoplanets. Here we study the survival and dynamics of exomoons under strong perturbations during giant planet scattering. During close encounters, planets and moons exchange orbital angular momentum and energy. The most common outcomes are the destruction of moons by ejection from the system, collision with the planets and the star, and scattering of moons onto perturbed but still planet-bound orbits. A small percentage of interesting moons can remain bound to ejected (free-floating) planets or be captured by a different planet. Moons' survival rate is correlated with planet observables such as mass, semi-major axis, eccentricity and inclination, as well as the close encounter distance and the number of close encounters. In addition, moons' survival rate and dynamical outcomes are predetermined by the moons' initial semi-major axes. The survival rate drops quickly as moons' distances increase, but simulations predict a good chance of survival for the Galilean moons. Moons with different dynamical outcomes occupy different regions of orbital parameter space, which may enable the study of moons' past evolution. Potential effects of planet obliquity evolution caused by close encounters on the satellites’ stability and dynamics will be reported, as well as detailed and systematic studies of individual close encounter events.

An extrasolar planetary system with three Neptune-mass planets.

Science.gov (United States)

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

2006-05-18

Over the past two years, the search for low-mass extrasolar planets has led to the detection of seven so-called 'hot Neptunes' or 'super-Earths' around Sun-like stars. These planets have masses 5-20 times larger than the Earth and are mainly found on close-in orbits with periods of 2-15 days. Here we report a system of three Neptune-mass planets with periods of 8.67, 31.6 and 197 days, orbiting the nearby star HD 69830. This star was already known to show an infrared excess possibly caused by an asteroid belt within 1 au (the Sun-Earth distance). Simulations show that the system is in a dynamically stable configuration. Theoretical calculations favour a mainly rocky composition for both inner planets, while the outer planet probably has a significant gaseous envelope surrounding its rocky/icy core; the outer planet orbits within the habitable zone of this star.

Direct Imaging Search for Extrasolar Planets in the Pleiades

NARCIS (Netherlands)

Yamamoto, K.; et al., [Unknown; Thalmann, C.

2013-01-01

We carried out an imaging survey for extrasolar planets around stars in the Pleiades (125 Myr, 135 pc) in the H and KS bands using HiCIAO combined with adaptive optics, AO188, on the Subaru telescope. We found 13 companion candidates fainter than 14.5 mag in the H band around 9 stars. Five of these

Exploring Disks Around Planets

Science.gov (United States)

Kohler, Susanna

2017-07-01

masses on the properties of the disks. Szulgyi specifically examines a range of planetary temperatures between 10,000 K and 1,000 K for the 1 MJ planet. Since the planet cools as it radiates away its formation heat, the different temperatures represent an evolutionary sequence over time.Predicted CharacteristicsSzulgyis work produced a number of intriguing observations, including the following:For the 1 MJ planet, a spherical circumplanetary envelope forms at high temperatures, flattening into a disk as the planet cools. Higher-mass planets form disks even at high temperatures.The disk has a steep temperature profile from inside to outside, and the whole disk is too hot for water to remain frozen. This suggests that satellites couldnt form in the disk earlier than 1 Myr after the planet birth. The outskirts of the disk cool first as the planet cools, indicating that satellites may eventually form in these outer parts and then migrate inward.The planets open gaps in the circumstellar disk as they orbit. As a planet radiates away its formation heat, the gap it opens becomes deeper and wider (though this is a small effect). For high-mass planets (5 MJ), the gap eccentricity increases, which creates a hostile environment for satellite formation.Szulgyi discusses a number of features of these disks that we can plan to search for in the future with our increasing telescope power including signatures in direct imaging and observations of their kinematics. The results from these simulations will help us both to detect these circumplanetary disks and to understand our observations when we do. These future observations will then allow us to learn about late-stage giant-planet formation as well as the formation of their satellites.CitationJ. Szulgyi 2017 ApJ 842 103. doi:10.3847/1538-4357/aa7515

Improving health aid for a better planet: The planning, monitoring and evaluation tool (PLANET).

Science.gov (United States)

Sridhar, Devi; Car, Josip; Chopra, Mickey; Campbell, Harry; Woods, Ngaire; Rudan, Igor

2015-12-01

International development assistance for health (DAH) quadrupled between 1990 and 2012, from US$ 5.6 billion to US$ 28.1 billion. This generates an increasing need for transparent and replicable tools that could be used to set investment priorities, monitor the distribution of funding in real time, and evaluate the impact of those investments. In this paper we present a methodology that addresses these three challenges. We call this approach PLANET, which stands for planning, monitoring and evaluation tool. Fundamentally, PLANET is based on crowdsourcing approach to obtaining information relevant to deployment of large-scale programs. Information is contributed in real time by a diverse group of participants involved in the program delivery. PLANET relies on real-time information from three levels of participants in large-scale programs: funders, managers and recipients. At each level, information is solicited to assess five key risks that are most relevant to each level of operations. The risks at the level of funders involve systematic neglect of certain areas, focus on donor's interests over that of program recipients, ineffective co-ordination between donors, questionable mechanisms of delivery and excessive loss of funding to "middle men". At the level of managers, the risks are corruption, lack of capacity and/or competence, lack of information and /or communication, undue avoidance of governmental structures / preference to non-governmental organizations and exclusion of local expertise. At the level of primary recipients, the risks are corruption, parallel operations / "verticalization", misalignment with local priorities and lack of community involvement, issues with ethics, equity and/or acceptability, and low likelihood of sustainability beyond the end of the program's implementation. PLANET is intended as an additional tool available to policy-makers to prioritize, monitor and evaluate large-scale development programs. In this, it should complement

The Search for Habitable Environments in the Solar System

Science.gov (United States)

McCleese, Daniel

2005-07-01

All space faring nations devote a portion of their resources to exploring thesolar system. NASA has a forty-year history of robotic missions reaching into deep spacefor a better understanding of our origins, the evolution of our planet, and our destiny.For the past decade, NASA has placed considerable emphasis on the search for life beyondEarth. Missions to the rocky terrestrial planets and the moons of the gas giants seekanswers to the question: Are other worlds in the solar system habitable by simpleorganisms? By framing its search objective in this way, NASA motivates investigations ofthe fundamentals of what makes a planet an abode for life, and what ingredients arerequired for the origin and evolution of life. In this lecture, we focus on thestrategies and results of the search thus far. We will discuss recent scientific missionsto Mars, Europa, and Titan.Dr. Dan McCleese is the Chief Scientist for NASA's Mars ExplorationProgram at JPL. In this role he has worked with NASA and the international sciencecommunity to establish the current science strategy for exploring Mars. Dan's personalscience interests are focused on acquiring and interpreting climatological data sets forthe terrestrial planets. Specific research topics include development of the firstclimatology of cloud height for Earth, upper atmospheric cloud and thermal structure ofVenus, and, at present, the modern climate of Mars. He is the Principal Investigator forthe Mars Climate Sounder on the Mars Reconnaissance Orbiter to be launched in 2005. Inthis investigation, measurements of atmospheric water vapor, temperature and condensates,and the energy balance of the polar caps are emphasized. Dr. McCleese was a FulbrightScholar at Oxford University receiving a D.Phil. degree in Atmospheric Physics.

The Blue Dot Workshop: Spectroscopic Search for Life on Extrasolar Planets

Science.gov (United States)

Des Marais, David J. (Editor)

1997-01-01

This workshop explored the key questions and challenges associated with detecting life on an extrasolar planet. The final product will be a NASA Conference Publication which includes the abstracts from 21 talks, summaries of key findings, and recommendations for future research. The workshop included sessions on three related topics: the biogeochemistry of biogenic gases in the atmosphere, the chemistry and spectroscopy of planetary atmospheres, and the remote sensing of planetary atmospheres and surfaces. With the observation that planetary formation is probably a common phenomenon, together with the advent of the technical capability to locate and describe extrasolar planets, this research area indeed has an exciting future.

Stellar oscillations in planet-hosting giant stars

Energy Technology Data Exchange (ETDEWEB)

Hatzes, Artie P; Zechmeister, Mathias [Thueringer Landessternwarte, Sternwarte 5, D-07778 (Germany)], E-mail: artie@tls-tautenburg.de

2008-10-15

Recently a number of giant extrasolar planets have been discovered around giant stars. These discoveries are important because many of these giant stars have intermediate masses in the range 1.2-3 Msun. Early-type main sequence stars of this mass range have been avoided by radial velocity planet search surveys due the difficulty of getting the requisite radial velocity precision needed for planet discoveries. Thus, giant stars can tell us about planet formation for stars more massive than the sun. However, the determination of stellar masses for giant stars is difficult due to the fact that evolutionary tracks for stars covering a wide range of masses converge to the same region of the H-R diagram. We report here on stellar oscillations in three planet-hosting giant stars: HD 13189, {beta} Gem, and {iota} Dra. Precise stellar radial velocity measurements for these stars show variations whose periods and amplitudes are consistent with solar-like p-mode oscillations. The implied stellar masses for these objects based on the characteristics of the stellar oscillations are consistent with the predictions of stellar isochrones. An investigation of stellar oscillations in planet hosting giant stars offers us the possibility of getting an independent determination of the stellar mass for these objects which is of crucial importance for extrasolar planet studies.

PLANETS AROUND THE K-GIANTS BD+20 274 AND HD 219415

International Nuclear Information System (INIS)

Gettel, S.; Wolszczan, A.; Niedzielski, A.; Nowak, G.; Adamów, M.; Zieliński, P.; Maciejewski, G.

2012-01-01

We present the discovery of planet-mass companions to two giant stars by the ongoing Penn State-Toruń Planet Search conducted with the 9.2 m Hobby-Eberly Telescope. The less massive of these stars, K5-giant BD+20 274, has a 4.2 M J minimum mass planet orbiting the star at a 578 day period and a more distant, likely stellar-mass companion. The best currently available model of the planet orbiting the K0-giant HD 219415 points to a ∼> Jupiter-mass companion in a 5.7 year, eccentric orbit around the star, making it the longest period planet yet detected by our survey. This planet has an amplitude of ∼18 m s –1 , comparable to the median radial velocity 'jitter', typical of giant stars.

From Extrasolar Planets to Exo-Earths

Science.gov (United States)

Fischer, Debra

2018-06-01

The ancient Greeks debated whether the Earth was unique, or innumerable worlds existed around other Suns. Twenty five years ago, technology and human ingenuity enabled the discovery of the first extrasolar planet candidates. The architectures of these first systems, with gas giant planets in star-skirting orbits, were unexpected and again raised an echo of that ancient question: is the Earth typical or unique? We are interested in this seemingly anthropocentric question because with all of our searching and discoveries, Earth is the only place where life has been found. It is the question of whether life exists elsewhere that energizes the search for exoplanets. The trajectory of this field has been stunning. After a steady stream of detections with the radial velocity method, a burst of discovery was made possible with the NASA Kepler mission. While thousands of smaller planets have now been found, true Earth analogs have eluded robust detection. However, we are sharpening the knives of our technology and without a doubt we now stand at the threshold of detecting hundreds of Earth analogs. Using Gaia, TESS, WFIRST, JWST and new ground-based spectrographs, we will learn the names and addresses of the worlds that orbit nearby stars and we will be ready to probe their atmospheres. We will finally resolve the ancient question of whether life is unique or common.

Developing a Systematic Patent Search Training Program

Science.gov (United States)

Zhang, Li

2009-01-01

This study aims to develop a systematic patent training program using patent analysis and citation analysis techniques applied to patents held by the University of Saskatchewan. The results indicate that the target audience will be researchers in life sciences, and aggregated patent database searching and advanced search techniques should be…

Outward Migration of Giant Planets in Orbital Resonance

Science.gov (United States)

D'Angelo, G.; Marzari, F.

2013-05-01

A pair of giant planets interacting with a gaseous disk may be subject to convergent orbital migration and become locked into a mean motion resonance. If the orbits are close enough, the tidal gaps produced by the planets in the disk may overlap. This represents a necessary condition to activate the outward migration of the pair. However, a number of other conditions must also be realized in order for this mechanism to operate. We have studied how disk properties, such as turbulence viscosity, temperature, surface density gradient, mass, and age, may affect the outcome of the outward migration process. We have also investigated the implications on this mechanism of the planets' gas accretion. If the pair resembles Jupiter and Saturn, the 3:2 orbital resonance may drive them outward until they reach stalling radii for migration, which are within ~10 AU of the star for disks representative of the early proto-solar nebula. However, planet post-formation conditions in the disk indicate that such planets become typically locked in the 1:2 orbital resonance, which does not lead to outward migration. Planet growth via gas accretion tends to alter the planets' mass-ratio and/or the disk accretion rate toward the star, reducing or inhibiting outward migration. Support from NASA Outer Planets Research Program and NASA Origins of Solar Systems Program is gratefully acknowledged.

A scientometric prediction of the discovery of the first potentially habitable planet with a mass similar to Earth.

Science.gov (United States)

Arbesman, Samuel; Laughlin, Gregory

2010-10-04

The search for a habitable extrasolar planet has long interested scientists, but only recently have the tools become available to search for such planets. In the past decades, the number of known extrasolar planets has ballooned into the hundreds, and with it, the expectation that the discovery of the first Earth-like extrasolar planet is not far off. Here, we develop a novel metric of habitability for discovered planets and use this to arrive at a prediction for when the first habitable planet will be discovered. Using a bootstrap analysis of currently discovered exoplanets, we predict the discovery of the first Earth-like planet to be announced in the first half of 2011, with the likeliest date being early May 2011. Our predictions, using only the properties of previously discovered exoplanets, accord well with external estimates for the discovery of the first potentially habitable extrasolar planet and highlight the the usefulness of predictive scientometric techniques to understand the pace of scientific discovery in many fields.

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.

Mathematical programming solver based on local search

CERN Document Server

Gardi, Frédéric; Darlay, Julien; Estellon, Bertrand; Megel, Romain

2014-01-01

This book covers local search for combinatorial optimization and its extension to mixed-variable optimization. Although not yet understood from the theoretical point of view, local search is the paradigm of choice for tackling large-scale real-life optimization problems. Today's end-users demand interactivity with decision support systems. For optimization software, this means obtaining good-quality solutions quickly. Fast iterative improvement methods, like local search, are suited to satisfying such needs. Here the authors show local search in a new light, in particular presenting a new kind of mathematical programming solver, namely LocalSolver, based on neighborhood search. First, an iconoclast methodology is presented to design and engineer local search algorithms. The authors' concern about industrializing local search approaches is of particular interest for practitioners. This methodology is applied to solve two industrial problems with high economic stakes. Software based on local search induces ex...

GLOBAL CHANGE RESEARCH NEWS #37: PUBLICATION OF "OUR CHANGING PLANET: THE FY 2002 U.S. GLOBAL CHANGE RESEARCH PROGRAM"

Science.gov (United States)

The EPA Global Change Research Program is pleased to inform you of the publication of the new Our Changing Planet: The FY 2002 U.S. Global Change Research Program. This annual report to the Congress was prepared under the auspices of the Committee on Environment and Natural Reso...

McDonald Observatory Planetary Search - A high precision stellar radial velocity survey for other planetary systems

Science.gov (United States)

Cochran, William D.; Hatzes, Artie P.

1993-01-01

The McDonald Observatory Planetary Search program surveyed a sample of 33 nearby F, G, and K stars since September 1987 to search for substellar companion objects. Measurements of stellar radial velocity variations to a precision of better than 10 m/s were performed as routine observations to detect Jovian planets in orbit around solar type stars. Results confirm the detection of a companion object to HD114762.

Are Job Search Programs a Promising Tool? : A Microeconometric Evaluation for Austria

OpenAIRE

Weber, Andrea Maria; Hofer, Helmut

2004-01-01

In Austria job search programs were introduced on a large scale in 1999. These programs aim at activating unemployed at an early stage and bringing them back to work by training job search related skills. We evaluate the impact of active labour market programs in Austria on individual unemployment durations, and allow program effects to vary between job search programs and formal training programs. We use the timing-of-events method which estimates the program effect as a shift in the transit...

Searching for transits in the Wide Field Camera Transit Survey with difference-imaging light curves

NARCIS (Netherlands)

Zendejas, Dominguez J.; Koppenhoefer, J.; Saglia, R.; Birkby, J.L.; Hodgkin, S.; Kovács, G.; Pinfield, D.; Sipocz, B.; Barrado, D.; Bender, R.; Burgo, del C.; Cappetta, M.; Martín, E.; Nefs, B.; Riffeser, A.; Steele, P.

2013-01-01

The Wide Field Camera Transit Survey is a pioneer program aiming at for searching extra-solar planets in the near-infrared. The images from the survey are processed by a data reduction pipeline, which uses aperture photometry to construct the light curves. We produce an alternative set of light

Automated Literature Searches for Longitudinal Tracking of Cancer Research Training Program Graduates.

Science.gov (United States)

Padilla, Luz A; Desmond, Renee A; Brooks, C Michael; Waterbor, John W

2018-06-01

A key outcome measure of cancer research training programs is the number of cancer-related peer-reviewed publications after training. Because program graduates do not routinely report their publications, staff must periodically conduct electronic literature searches on each graduate. The purpose of this study is to compare findings of an innovative computer-based automated search program versus repeated manual literature searches to identify post-training peer-reviewed publications. In late 2014, manual searches for publications by former R25 students identified 232 cancer-related articles published by 112 of 543 program graduates. In 2016, a research assistant was instructed in performing Scopus literature searches for comparison with individual PubMed searches on our 543 program graduates. Through 2014, Scopus found 304 cancer publications, 220 of that had been retrieved manually plus an additional 84 papers. However, Scopus missed 12 publications found manually. Together, both methods found 316 publications. The automated method found 96.2 % of the 316 publications while individual searches found only 73.4 %. An automated search method such as using the Scopus database is a key tool for conducting comprehensive literature searches, but it must be supplemented with periodic manual searches to find the initial publications of program graduates. A time-saving feature of Scopus is the periodic automatic alerts of new publications. Although a training period is needed and initial costs can be high, an automated search method is worthwhile due to its high sensitivity and efficiency in the long term.

Planets and Life

Science.gov (United States)

Sullivan, Woodruff T., III; Baross, John

2007-09-01

Foreword; Preface; Contributors; Prologue; Part I. History: 1. History of astrobiological ideas W. T. Sullivan and D. Carney; 2. From exobiology to astrobiology S. J. Dick; Part II. The Physical Stage: 3. Formation of Earth-like habitable planets D. E. Brownlee and M. Kress; 4. Planetary atmospheres and life D. Catling and J. F. Kasting; Part III. The Origin of Life on Earth: 5. Does 'life' have a definition? C.E. Cleland and C. F. Chyba; 6. Origin of life: crucial issues R. Shapiro; 7. Origin of proteins and nucleic acids A. Ricardo and S. A. Benner; 8. The roots of metabolism G.D. Cody and J. H. Scott; 9. Origin of cellular life D. W. Deamer; Part IV. Life on Earth: 10. Evolution: a defining feature of life J. A. Baross; 11. Evolution of metabolism and early microbial communities J. A. Leigh, D. A. Stahl and J. T. Staley; 12. The earliest records of life on Earth R. Buick; 13. The origin and diversification of eukaryotes M. L. Sogin, D. J. Patterson and A. McArthur; 14. Limits of carbon life on Earth and elsewhere J. A. Baross, J. Huber and M. Schrenk; 15. Life in ice J. W. Deming and H. Eicken; 16. The evolution and diversification of life S. Awramik and K. J. McNamara; 17. Mass extinctions P. D. Ward; Part V. Potentially Habitable Worlds: 18. Mars B. M. Jakosky, F. Westall and A. Brack; 19. Europa C. F. Chyba and C. B. Phillips; 20. Titan J. I. Lunine and B. Rizk; 21. Extrasolar planets P. Butler; Part VI. Searching for Extraterrestrial Life: 22. How to search for life on other worlds C. P. McKay; 23. Instruments and strategies for detecting extraterrestrial life P. G. Conrad; 24. Societial and ethical concerns M. S. Race; 25. Planetary protection J. D. Rummel; 26. Searching for extraterrestrial intelligence J. C. Tarter; 27. Alien biochemistries P. D. Ward and S. A. Benner; Part VII. Future of the Field: 28. Disciplinary and educational opportunities L. Wells, J. Armstrong and J. Huber; Epilogue C. F. Chyba; Appendixes: A. Units and usages; B. Planetary

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.

GLOBAL CHANGE RESEARCH NEWS #8: OUR CHANGING PLANET: THE FY2000 U.S. GLOBAL CHANGE RESEARCH PROGRAM

Science.gov (United States)

This edition of Global Change Research News focuses on the publication of the new OurChanging Planet: The FY2000 U.S. Global Change Research Program. This annual report to the Congress was prepared under the auspices ofthe President's National Science and Technology Council. It...

ENHANCED INTERFEROMETRIC IDENTIFICATION OF SPECTRA IN HABITABLE EXTRASOLAR PLANETS

International Nuclear Information System (INIS)

Schwartz, Eyal; Lipson, Stephen G.; Ribak, Erez N.

2012-01-01

An Earth-like extrasolar planet emits light that is many orders of magnitude fainter than that of the parent star. We propose a method of identifying bio-signature spectral lines in light of known extrasolar planets based on Fourier spectroscopy in the infrared, using an off-center part of a Fourier interferogram only. This results in superior sensitivity to narrower molecular-type spectral bands, which are expected in the planet spectrum but are absent in the parent star. We support this idea by numerical simulations that include photon and thermal noise, and show it to be feasible at a luminosity ratio of 10 –6 for a Sun-like parent star in the infrared. We also carried out a laboratory experiment to illustrate the method. The results suggest that this method should be applicable to real planet searches.

Stabilizing Cloud Feedback Dramatically Expands the Habitable Zone of Tidally Locked Planets

OpenAIRE

Yang, Jun; Cowan, Nicolas B.; Abbot, Dorian S.

2013-01-01

The habitable zone (HZ) is the circumstellar region where a planet can sustain surface liquid water. Searching for terrestrial planets in the HZ of nearby stars is the stated goal of ongoing and planned extrasolar planet surveys. Previous estimates of the inner edge of the HZ were based on one-dimensional radiative-convective models. The most serious limitation of these models is the inability to predict cloud behavior. Here we use global climate models with sophisticated cloud schemes to sho...

Predictions for shepherding planets in scattered light images of debris disks

International Nuclear Information System (INIS)

Rodigas, Timothy J.; Hinz, Philip M.; Malhotra, Renu

2014-01-01

Planets can affect debris disk structure by creating gaps, sharp edges, warps, and other potentially observable signatures. However, there is currently no simple way for observers to deduce a disk-shepherding planet's properties from the observed features of the disk. Here we present a single equation that relates a shepherding planet's maximum mass to the debris ring's observed width in scattered light, along with a procedure to estimate the planet's eccentricity and minimum semimajor axis. We accomplish this by performing dynamical N-body simulations of model systems containing a star, a single planet, and an exterior disk of parent bodies and dust grains to determine the resulting debris disk properties over a wide range of input parameters. We find that the relationship between planet mass and debris disk width is linear, with increasing planet mass producing broader debris rings. We apply our methods to five imaged debris rings to constrain the putative planet masses and orbits in each system. Observers can use our empirically derived equation as a guide for future direct imaging searches for planets in debris disk systems. In the fortuitous case of an imaged planet orbiting interior to an imaged disk, the planet's maximum mass can be estimated independent of atmospheric models.

On the Possibility of Habitable Trojan Planets in Binary Star Systems.

Science.gov (United States)

Schwarz, Richard; Funk, Barbara; Bazsó, Ákos

2015-12-01

Approximately 60% of all stars in the solar neighbourhood (up to 80% in our Milky Way) are members of binary or multiple star systems. This fact led to the speculations that many more planets may exist in binary systems than are currently known. To estimate the habitability of exoplanetary systems, we have to define the so-called habitable zone (HZ). The HZ is defined as a region around a star where a planet would receive enough radiation to maintain liquid water on its surface and to be able to build a stable atmosphere. We search for new dynamical configurations-where planets may stay in stable orbits-to increase the probability to find a planet like the Earth.

A scientometric prediction of the discovery of the first potentially habitable planet with a mass similar to Earth.

Directory of Open Access Journals (Sweden)

Samuel Arbesman

Full Text Available BACKGROUND: The search for a habitable extrasolar planet has long interested scientists, but only recently have the tools become available to search for such planets. In the past decades, the number of known extrasolar planets has ballooned into the hundreds, and with it, the expectation that the discovery of the first Earth-like extrasolar planet is not far off. METHODOLOGY/PRINCIPAL FINDINGS: Here, we develop a novel metric of habitability for discovered planets and use this to arrive at a prediction for when the first habitable planet will be discovered. Using a bootstrap analysis of currently discovered exoplanets, we predict the discovery of the first Earth-like planet to be announced in the first half of 2011, with the likeliest date being early May 2011. CONCLUSIONS/SIGNIFICANCE: Our predictions, using only the properties of previously discovered exoplanets, accord well with external estimates for the discovery of the first potentially habitable extrasolar planet and highlight the the usefulness of predictive scientometric techniques to understand the pace of scientific discovery in many fields.

HABITABLE PLANETS ECLIPSING BROWN DWARFS: STRATEGIES FOR DETECTION AND CHARACTERIZATION

International Nuclear Information System (INIS)

Belu, Adrian R.; Selsis, Franck; Raymond, Sean N.; Bolmont, Emeline; Pallé, Enric; Street, Rachel; Sahu, D. K.; Anupama, G. C.; Von Braun, Kaspar; Figueira, Pedro; Ribas, Ignasi

2013-01-01

Given the very close proximity of their habitable zones, brown dwarfs (BDs) represent high-value targets in the search for nearby transiting habitable planets that may be suitable for follow-up occultation spectroscopy. In this paper, we develop search strategies to find habitable planets transiting BDs depending on their maximum habitable orbital period (P HZ o ut ). Habitable planets with P HZ o ut shorter than the useful duration of a night (e.g., 8-10 hr) can be screened with 100% completeness from a single location and in a single night (near-IR). More luminous BDs require continuous monitoring for longer duration, e.g., from space or from a longitude-distributed network (one test scheduling achieved three telescopes, 13.5 contiguous hours). Using a simulated survey of the 21 closest known BDs (within 7 pc) we find that the probability of detecting at least one transiting habitable planet is between 4.5 +5.6 -1.4 % and 56 +31 -13 %, depending on our assumptions. We calculate that BDs within 5-10 pc are characterizable for potential biosignatures with a 6.5 m space telescope using ∼1% of a five-year mission's lifetime spread over a contiguous segment only one-fifth to one-tenth of this duration.

Detection of planet candidates around K giants. HD 40956, HD 111591, and HD 113996

Science.gov (United States)

Jeong, G.; Lee, B.-C.; Han, I.; Omiya, M.; Izumiura, H.; Sato, B.; Harakawa, H.; Kambe, E.; Mkrtichian, D.

2018-02-01

Aims: The purpose of this paper is to detect and investigate the nature of long-term radial velocity (RV) variations of K-type giants and to confirm planetary companions around the stars. Methods: We have conducted two planet search programs by precise RV measurement using the 1.8 m telescope at Bohyunsan Optical Astronomy Observatory (BOAO) and the 1.88 m telescope at Okayama Astrophysical Observatory (OAO). The BOAO program searches for planets around 55 early K giants. The OAO program is looking for 190 G-K type giants. Results: In this paper, we report the detection of long-period RV variations of three K giant stars, HD 40956, HD 111591, and HD 113996. We investigated the cause of the observed RV variations and conclude the substellar companions are most likely the cause of the RV variations. The orbital analyses yield P = 578.6 ± 3.3 d, m sin i = 2.7 ± 0.6 MJ, a = 1.4 ± 0.1 AU for HD 40956; P = 1056.4 ± 14.3 d, m sin i = 4.4 ± 0.4 MJ, a = 2.5 ± 0.1 AU for HD 111591; P = 610.2 ± 3.8 d, m sin i = 6.3 ± 1.0 MJ, a = 1.6 ± 0.1 AU for HD 113996. Based on observations made with the BOES at BOAO in Korea and HIDES at OAO in Japan.Tables 3-5 are 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/610/A3

Hybrid Differential Dynamic Programming with Stochastic Search

Science.gov (United States)

Aziz, Jonathan; Parker, Jeffrey; Englander, Jacob

2016-01-01

Differential dynamic programming (DDP) has been demonstrated as a viable approach to low-thrust trajectory optimization, namely with the recent success of NASAs Dawn mission. The Dawn trajectory was designed with the DDP-based Static Dynamic Optimal Control algorithm used in the Mystic software. Another recently developed method, Hybrid Differential Dynamic Programming (HDDP) is a variant of the standard DDP formulation that leverages both first-order and second-order state transition matrices in addition to nonlinear programming (NLP) techniques. Areas of improvement over standard DDP include constraint handling, convergence properties, continuous dynamics, and multi-phase capability. DDP is a gradient based method and will converge to a solution nearby an initial guess. In this study, monotonic basin hopping (MBH) is employed as a stochastic search method to overcome this limitation, by augmenting the HDDP algorithm for a wider search of the solution space.

Planet hunters. VI. An independent characterization of KOI-351 and several long period planet candidates from the Kepler archival data

International Nuclear Information System (INIS)

Schmitt, Joseph R.; Wang, Ji; Fischer, Debra A.; Moriarty, John C.; Boyajian, Tabetha S.; Jek, Kian J.; LaCourse, Daryll; Omohundro, Mark R.; Winarski, Troy; Goodman, Samuel Jon; Jebson, Tony; Schwengeler, Hans Martin; Paterson, David A.; Schwamb, Megan E.; Lintott, Chris; Simpson, Robert; Lynn, Stuart; Smith, Arfon M.; Parrish, Michael; Schawinski, Kevin

2014-01-01

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.

Mission to Planet Earth

International Nuclear Information System (INIS)

Wilson, G.S.; Backlund, P.W.

1992-01-01

Mission to Planet Earth (MTPE) is NASA's concept for an international science program to produce the understanding needed to predict changes in the earth's environment. NASA and its interagency and international partners will place satellites carrying advanced sensors in strategic earth orbits to gather multidisciplinary data. A sophisticated data system will process and archive an unprecedented amount of information about the earth and how it works as a system. Increased understanding of the earth system is a basic human responsibility, a prerequisite to informed management of the planet's resources and to the preservation of the global environment. 8 refs

Mission to Planet Earth

Science.gov (United States)

Tilford, Shelby G.; Asrar, Ghassem; Backlund, Peter W.

1994-01-01

Mission to Planet Earth (MTPE) is NASA's concept for an international science program to produce the understanding needed to predict changes in the Earth's environment. NASA and its interagency and international partners will place satellites carrying advanced sensors in strategic Earth orbits to gather multidisciplinary data. A sophisticated data system will process and archive an unprecedented amount of information about the Earth and how it works as a system. Increased understanding of the Earth system is a basic human responsibility, a prerequisite to informed management of the planet's resources and to the preservation of the global environment.

ASTROMETRY AND RADIAL VELOCITIES OF THE PLANET HOST M DWARF GJ 317: NEW TRIGONOMETRIC DISTANCE, METALLICITY, AND UPPER LIMIT TO THE MASS OF GJ 317b

International Nuclear Information System (INIS)

Anglada-Escudé, Guillem; Boss, Alan P.; Weinberger, Alycia J.; Butler, R. Paul; Thompson, Ian B.; Vogt, Steven S.; Rivera, Eugenio J.

2012-01-01

We have obtained precision astrometry of the planet host M dwarf GJ 317 in the framework of the Carnegie Astrometric Planet Search project. The new astrometric measurements give a distance determination of 15.3 pc, 65% further than previous estimates. The resulting absolute magnitudes suggest that it is metal-rich and more massive than previously assumed. This result strengthens the correlation between high metallicity and the presence of gas giants around low-mass stars. At 15.3 pc, the minimal astrometric amplitude for planet candidate GJ 317b is 0.3 mas (edge-on orbit), just below our astrometric sensitivity. However, given the relatively large number of observations and good astrometric precision, a Bayesian Monte Carlo Markov Chain analysis indicates that the mass of planet b has to be smaller than twice the minimum mass with a 99% confidence level, with a most likely value of 2.5 M Jup . Additional radial velocity (RV) measurements obtained with Keck by the Lick-Carnegie Planet search program confirm the presence of an additional very long period planet candidate, with a period of 20 years or more. Even though such an object will imprint a large astrometric wobble on the star, its curvature is yet not evident in the astrometry. Given high metallicity, and the trend indicating that multiple systems are rich in low-mass companions, this system is likely to host additional low-mass planets in its habitable zone that can be readily detected with state-of-the-art optical and near-infrared RV measurements.

ASTROMETRY AND RADIAL VELOCITIES OF THE PLANET HOST M DWARF GJ 317: NEW TRIGONOMETRIC DISTANCE, METALLICITY, AND UPPER LIMIT TO THE MASS OF GJ 317b

Energy Technology Data Exchange (ETDEWEB)

Anglada-Escude, Guillem; Boss, Alan P.; Weinberger, Alycia J.; Butler, R. Paul [Department of Terrestrial Magnetism, Carnegie Institution for Science, 5241 Broad Branch Road NW, Washington, DC 20015 (United States); Thompson, Ian B. [Carnegie Observatories, 813 Santa Barbara Street, Pasadena, CA 91101 (United States); Vogt, Steven S.; Rivera, Eugenio J., E-mail: anglada@dtm.ciw.edu [UCO/Lick Observatory, University of California, Santa Cruz, CA 95064 (United States)

2012-02-10

We have obtained precision astrometry of the planet host M dwarf GJ 317 in the framework of the Carnegie Astrometric Planet Search project. The new astrometric measurements give a distance determination of 15.3 pc, 65% further than previous estimates. The resulting absolute magnitudes suggest that it is metal-rich and more massive than previously assumed. This result strengthens the correlation between high metallicity and the presence of gas giants around low-mass stars. At 15.3 pc, the minimal astrometric amplitude for planet candidate GJ 317b is 0.3 mas (edge-on orbit), just below our astrometric sensitivity. However, given the relatively large number of observations and good astrometric precision, a Bayesian Monte Carlo Markov Chain analysis indicates that the mass of planet b has to be smaller than twice the minimum mass with a 99% confidence level, with a most likely value of 2.5 M{sub Jup}. Additional radial velocity (RV) measurements obtained with Keck by the Lick-Carnegie Planet search program confirm the presence of an additional very long period planet candidate, with a period of 20 years or more. Even though such an object will imprint a large astrometric wobble on the star, its curvature is yet not evident in the astrometry. Given high metallicity, and the trend indicating that multiple systems are rich in low-mass companions, this system is likely to host additional low-mass planets in its habitable zone that can be readily detected with state-of-the-art optical and near-infrared RV measurements.

A "feasible direction" search for Lineal Programming problem solving

Directory of Open Access Journals (Sweden)

Jaime U Malpica Angarita

2003-07-01

Full Text Available The study presents an approach to solve linear programming problems with no artificial variables. A primal linear minimization problem is standard form and its associated dual linear maximization problem are used. Initially, the dual (or a partial dual program is solved by a "feasible direction" search, where the Karush-Kuhn-Tucker conditions help to verify its optimality and then its feasibility. The "feasible direction" search exploits the characteristics of the convex polyhedron (or prototype formed by the dual program constraints to find a starting point and then follows line segments, whose directions are found in afine subspaces defined by boundary hyperplanes of polyhedral faces, to find next points up to the (an optimal one. Them, the remaining dual constraints not satisfaced at that optimal dual point, if there are any, are handled as nonbasic variables of the primal program, which is to be solved by such "feasible direction" search.

Arc-Search Infeasible Interior-Point Algorithm for Linear Programming

OpenAIRE

Yang, Yaguang

2014-01-01

Mehrotra's algorithm has been the most successful infeasible interior-point algorithm for linear programming since 1990. Most popular interior-point software packages for linear programming are based on Mehrotra's algorithm. This paper proposes an alternative algorithm, arc-search infeasible interior-point algorithm. We will demonstrate, by testing Netlib problems and comparing the test results obtained by arc-search infeasible interior-point algorithm and Mehrotra's algorithm, that the propo...

On the Biohabitability of M-dwarf Planets

Science.gov (United States)

Wandel, A.

2018-04-01

The recent detection of Earth-sized planets in the habitable zone of Proxima Centauri, Trappist-1, and many other nearby M-type stars has led to speculations whether liquid water and life actually exist on these planets. To a large extent, the answer depends on their yet unknown atmospheres, which may, however, be within observational reach in the near future by JWST, ELT, and other planned telescopes. We consider the habitability of planets of M-type stars in the context of their atmospheric properties, heat transport, and irradiation. Instead of the traditional definition of the habitable zone, we define the biohabitable zone, where liquid water and complex organic molecules can survive on at least part of the planetary surface. The atmospheric impact on the temperature is quantified in terms of the heating factor (a combination of greenhouse heating, stellar irradiation, albedo, etc.) and heat redistribution (horizontal energy transport). We investigate the biohabitable domain (where planets can support surface liquid water and organics) in terms of these two factors. Our results suggest that planets orbiting M-type stars may have life-supporting temperatures, at least on part of their surface, for a wide range of atmospheric properties. We apply this analyses to Proxima Cen b and the Trappist-1 system. Finally, we discuss the implications for the search of biosignatures and demonstrate how they may be used to estimate the abundance of photosynthesis and biotic planets.

HABITABLE PLANETS ECLIPSING BROWN DWARFS: STRATEGIES FOR DETECTION AND CHARACTERIZATION

Energy Technology Data Exchange (ETDEWEB)

Belu, Adrian R.; Selsis, Franck; Raymond, Sean N.; Bolmont, Emeline [Universite de Bordeaux, LAB, UMR 5804, F-33270, Floirac (France); Palle, Enric [Instituto de Astrofisica de Canarias, E-38205 La Laguna (Spain); Street, Rachel [Las Cumbres Observatory Global Telescope Network, 6740 Cortona Drive, Suite 102, Goleta, CA 93117 (United States); Sahu, D. K.; Anupama, G. C. [Indian Institute of Astrophysics, Koramangala, Bangalore 560034 (India); Von Braun, Kaspar [NASA Exoplanet Science Institute, California Institute of Technology, MC 100-22, Pasadena, CA 91125 (United States); Figueira, Pedro [Centro de Astrofisica, Universidade do Porto, Rua das Estrelas, 4150-762 Porto (Portugal); Ribas, Ignasi, E-mail: belu@obs.u-bordeaux1.fr [Institut de Ciencies de l' Espai (CSIC-IEEC), Campus UAB, Facultat de Ciencies, Torre C5, parell, 2a pl., E-08193 Bellaterra (Spain)

2013-05-10

Given the very close proximity of their habitable zones, brown dwarfs (BDs) represent high-value targets in the search for nearby transiting habitable planets that may be suitable for follow-up occultation spectroscopy. In this paper, we develop search strategies to find habitable planets transiting BDs depending on their maximum habitable orbital period (P{sub HZ{sub out}}). Habitable planets with P{sub HZ{sub out}} shorter than the useful duration of a night (e.g., 8-10 hr) can be screened with 100% completeness from a single location and in a single night (near-IR). More luminous BDs require continuous monitoring for longer duration, e.g., from space or from a longitude-distributed network (one test scheduling achieved three telescopes, 13.5 contiguous hours). Using a simulated survey of the 21 closest known BDs (within 7 pc) we find that the probability of detecting at least one transiting habitable planet is between 4.5{sup +5.6}{sub -1.4}% and 56{sup +31}{sub -13}%, depending on our assumptions. We calculate that BDs within 5-10 pc are characterizable for potential biosignatures with a 6.5 m space telescope using {approx}1% of a five-year mission's lifetime spread over a contiguous segment only one-fifth to one-tenth of this duration.

The Gemini Planet Imager Exoplanet Survey

Science.gov (United States)

Nielsen, Eric L.; Macintosh, Bruce; Graham, James R.; Barman, Travis S.; Doyon, Rene; Fabrycky, Daniel; Fitzgerald, Michael P.; Kalas, Paul; Konopacky, Quinn M.; Marchis, Franck; Marley, Mark S.; Marois, Christian; Patience, Jenny; Perrin, Marshall D.; Oppenheimer, Rebecca; Song, Inseok; GPIES Team

2017-01-01

The Gemini Planet Imager Exoplanet Survey (GPIES) is one of the largest most sensitive direct imaging searches for exoplanets conducted to date, and having observed more than 300 stars the survey is halfway complete. We present highlights from the first half of the survey, including the discovery and characterization of the young exoplanet 51 Eri b and the brown dwarf HR 2562 B, new imaging of multiple disks, and resolving the young stellar binary V343 Nor for the first time. GPI has also provided new spectra and orbits of previous known planets and brown dwarfs and polarization measurements of a wide range of disks. Finally, we discuss the constraints placed by the first half of the GPIES campaign on the population of giant planets at orbital separations beyond that of Jupiter. Supported by NSF grants AST-0909188 and AST-1313718, AST-1411868, AST 141378, NNX11AF74G, and DGE-1232825, and by NASA grants NNX15AD95G/NEXSS and NNX11AD21G.

Factors Affecting the Habitability of Earth-like Planets

Science.gov (United States)

Meadows, Victoria; NAI-Virtual Planetary Laboratory Team

2014-03-01

Habitability is a measure of an environment's potential to support life. For exoplanets, the concept of habitability can be used broadly - to inform our calculations of the possibility and distribution of life elsewhere - or as a practical tool to inform mission designs and to prioritize specific targets in the search for extrasolar life. Although a planet's habitability does depend critically on the effect of stellar type and planetary semi-major axis on climate balance, work in the interdisciplinary field of astrobiology has identified many additional factors that can affect a planet's environment and its potential ability to support life. Life requires material for metabolism and structures, a liquid medium for chemical transport, and an energy source to drive metabolism and other life processes. Whether a planet's surface or sub-surface can provide these requirements is the result of numerous planetary and astrophysical processes that affect the planet's formation and evolution. Many of these factors are interdependent, and fall into three main categories: stellar effects, planetary effects and planetary system effects. Key abiotic processes affecting the resultant planetary environment include photochemistry (e.g. Segura et al., 2003; 2005), stellar effects on climate balance (e.g. Joshii et al., 2012; Shields et al., 2013), atmospheric loss (e.g. Lopez and Fortney, 2013), and gravitational interactions with the star (e.g. Barnes et al., 2013). In many cases, the effect of these processes is strongly dependent on a specific planet's existing environmental properties. Examples include the resultant UV flux at a planetary surface as a product of stellar activity and the strength of a planet's atmospheric UV shield (Segura et al., 2010); and the amount of tidal energy available to a planet to drive plate tectonics and heat the surface (Barnes et al., 2009), which is in turn due to a combination of stellar mass, planetary mass and composition, planetary orbital

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

Strategies for the search of life in the universe

OpenAIRE

Schneider, Jean

1996-01-01

The discovery of an increasing number of Jupiter-like planets in orbit around other stars (or extra-solar planets) is a promising first step toward the search for Life in the Universe. We review all aspects of the question: - definition of Life - definition and characterization of the `habitable zone' around a star - overview of detection methods of planets, with special attention to habitable planets - present fingings - future projects.

Beyond the principle of plentitude: a review of terrestrial planet habitability.

Science.gov (United States)

Gaidos, E; Deschenes, B; Dundon, L; Fagan, K; Menviel-Hessler, L; Moskovitz, N; Workman, M

2005-04-01

We review recent work that directly or indirectly addresses the habitability of terrestrial (rocky) planets like the Earth. Habitability has been traditionally defined in terms of an orbital semimajor axis within a range known as the habitable zone, but it is also well known that the habitability of Earth is due to many other astrophysical, geological, and geochemical factors. We focus this review on (1) recent refinements to habitable zone calculations; (2) the formation and orbital stability of terrestrial planets; (3) the tempo and mode of geologic activity (e.g., plate tectonics) on terrestrial planets; (4) the delivery of water to terrestrial planets in the habitable zone; and (5) the acquisition and loss of terrestrial planet carbon and nitrogen, elements that constitute important atmospheric gases responsible for habitable conditions on Earth's surface as well as being the building blocks of the biosphere itself. Finally, we consider recent work on evidence for the earliest habitable environments and the appearance of life itself on our planet. Such evidence provides us with an important, if nominal, calibration point for our search for other habitable worlds.

Tc Trends and Terrestrial Planet Formation: The Case of Zeta Reticuli

Science.gov (United States)

Adibekyan, Vardan; Delgado-Mena, Elisa; Figueira, Pedro; Sousa, Sergio; Santos, Nuno; Faria, Joao; González Hernández, Jonay; Israelian, Garik; Harutyunyan, Gohar; Suárez-Andrés, Lucia; Hakobyan, Artur

2016-11-01

During the last decade astronomers have been trying to search for chemical signatures of terrestrial planet formation in the atmospheres of the hosting stars. Several studies suggested that the chemical abundance trend with the condensation temperature, Tc, is a signature of rocky planet formation. In particular, it was suggested that the Sun shows 'peculiar' chemical abundances due to the presence of the terrestrial planets in our solar-system. However, the rocky material accretion or the trap of rocky materials in terrestrial planets is not the only explanation for the chemical 'peculiarity' of the Sun, or other Sun-like stars with planets. In this talk I madea very brief review of this topic, and presented our last results for the particular case of Zeta Reticuli binary system: A very interesting and well-known system (known in science fiction and ufology as the world of Grey Aliens, or Reticulans) where one of the components hosts an exo-Kuiper belt, and the other component is a 'single', 'lonely' star.

Geologic Exploration of the Planets: A Personal Retrospective of the First 50 years

Science.gov (United States)

Carr, M. H.

2013-12-01

The modern era of exploration of planets and satellites beyond the Earth-Moon system began on 14 December 1962 when the Mariner 2 spacecraft flew by Venus. Since that time roughly 80 spacecraft have successfully visited other planets and their satellites. In 1962 we knew nothing of the geology of the non-terrestrial planets and satellites; they were just variously shaded discs and dots. Most of us entering the new field of planetary geology at the time did so in anticipation of the Apollo lunar landings. I was hired by Gene Shoemaker to work on lunar issues and to participate in the lunar geologic mapping program that he had initiated at the USGS. Lunar studies led naturally to planetary studies but none of us could have anticipated the geologic variety that exists within the Solar System as exemplified by the coronae of Venus, the canyons of Mars, the volcanoes of Io, the ice tectonics of Europa and Ganymede, the geysers of Enceladus and the methane-carved valleys of Titan. Although Mars appeared lunar-like in the first close-up images from the Mariner 4 (1965) and Mariners 6 and 7 (1969) fly-bys, the Mariner 9 (1971) orbiter soon revealed Mars' geologic variety. Planning imaging for Mariner 9 was challenging; aids were primitive and we essentially had a blank sheet to fill. By 1971, the Viking Project with its main objective to land on Mars and search for signs of life was well underway. In 1969 I was appointed leader of the Viking Orbiter imaging team. The main function of the cameras was to ensure that the landing sites were safe before landing. In 1976 when we acquired the first close-up images of the pre-chosen landing sites they were greeted with elation and horror, elation because of their quality, horror because of the roughness of the terrain that had seemed so smooth in the Mariner 9 images. There followed an intense period of searching for safer sites and ultimately the two landers did land safely. The search for life then followed with hopes soaring as

ALMOST ALL OF KEPLER'S MULTIPLE-PLANET CANDIDATES ARE PLANETS

International Nuclear Information System (INIS)

Lissauer, Jack J.; Rowe, Jason F.; Bryson, Stephen T.; Howell, Steve B.; Jenkins, Jon M.; Kinemuchi, Karen; Koch, David G.; Marcy, Geoffrey W.; Adams, Elisabeth; Fressin, Francois; Geary, John; Holman, Matthew J.; Ragozzine, Darin; Buchhave, Lars A.; Ciardi, David R.; Cochran, William D.; Fabrycky, Daniel C.; Ford, Eric B.; Morehead, Robert C.; Gilliland, Ronald L.

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 detectable planets tend to come in systems and/or if the orbital planes of planets encircling the same star are correlated. There are more than one hundred times as many Kepler planet candidates in multi-candidate systems as would be predicted from a random distribution of candidates, implying that the vast majority are true planets. Most of these multis are multiple-planet systems orbiting the Kepler target star, but there are likely cases where (1) the planetary system orbits a fainter star, and the planets are thus significantly larger than has been estimated, or (2) the planets orbit different stars within a binary/multiple star system. We use the low overall false-positive rate among Kepler multis, together with analysis of Kepler spacecraft and ground-based data, to validate the closely packed Kepler-33 planetary system, which orbits a star that has evolved somewhat off of the main sequence. Kepler-33 hosts five transiting planets, with periods ranging from 5.67 to 41 days.

Kepler: NASA's First Mission Capable of Finding Earth-Size Planets

Science.gov (United States)

Borucki, William J.

2009-01-01

Kepler, a NASA Discovery mission, is a spaceborne telescope designed to search a nearby region of our galaxy for Earth-size planets orbiting in the habitable zone of stars like our sun. The habitable zone is that region around a start where the temperature permits water to be liquid on the surface of a planet. Liquid water is considered essential forth existence of life. Mission Phases: Six mission phases have been defined to describe the different periods of activity during Kepler's mission. These are: launch; commissioning; early science operations, science operations: and decommissioning

Constraints on planet formation from Kepler’s multiple planet systems

Science.gov (United States)

Quintana, Elisa V.

2015-01-01

The recent haul of hundreds of multiple planet systems discovered by Kepler provides a treasure trove of new clues for planet formation theories. The substantial amount of protoplanetary disk mass needed to form the most commonly observed multi-planet systems - small (Earth-sized to mini-Neptune-sized) planets close to their stars - argues against pure in situ formation and suggests that the planets in these systems must have undergone some form of migration. I will present results from numerical simulations of terrestrial planet formation that aim to reproduce the sizes and architecture of Kepler's multi-planet systems, and will discuss the observed resonances and giant planets (or the lack thereof) associated with these systems.

Spectral differential imaging detection of planets about nearby stars

International Nuclear Information System (INIS)

Smith, W.H.

1987-01-01

Direct ground-based optical imaging of planets in orbit about nearby stars may be accomplished by spectral differential imaging using multiple passband acoustooptic filters with a CCD. This technique provides two essential results. First, it provides a means to modulate the stellar flux reflected from a planet while leaving the flux from the star and other sources in the same field of view unmodulated. Second, spectral differential imaging enables the CCD detector to achieve a sufficiently high dynamic range to locate planets near a star in spite of an integrated brightness differential of 5 x 10 8 . Spectral differential imaging at nearby diffraction limited imaging conditions with telescope apodization can reduce the time to conduct a sensitive planetary search to a few hours in some cases. The feasibility of this idea is discussed here and shown to provide, in principle, the discrimination and sensitivity to detect a Jovian-class planet about stars at distances of about 10 parsecs. The detection of brown dwarfs is shown to be feasible as well. 31 references

TRIGONOMETRIC PARALLAXES AND PROPER MOTIONS OF 134 SOUTHERN LATE M, L, AND T DWARFS FROM THE CARNEGIE ASTROMETRIC PLANET SEARCH PROGRAM

Energy Technology Data Exchange (ETDEWEB)

Weinberger, Alycia J.; Boss, Alan P.; Keiser, Sandra A. [Department of Terrestrial Magnetism, Carnegie Institution for Science, 5241 Broad Branch Road, NW, Washington, DC 20015-1305 (United States); Anglada-Escudé, Guillem [School of Physics and Astronomy, Queen Mary University of London, 327 Mile End Road, London, E1 4NS (United Kingdom); Thompson, Ian B. [Carnegie Observatories, Carnegie Institution for Science, 813 Santa Barbara Street, Pasadena, CA 91101-1292 (United States); Burley, Gregory [National Research Council of Canada, 5071 West Saanich Road, Victoria, BC V9E 2E7 (Canada)

2016-07-01

We report trigonometric parallaxes for 134 low-mass stars and brown dwarfs, of which 38 have no previously published measurement and 79 more have improved uncertainties. Our survey focused on nearby targets, so 119 are closer than 30 pc. Of the 38 stars with new parallaxes, 14 are within 20 pc and seven are likely brown dwarfs (spectral types later than L0). These parallaxes are useful for studies of kinematics, multiplicity, and spectrophotometric calibration. Two objects with new parallaxes are confirmed as young stars with membership in nearby young moving groups: LP 870-65 in AB Doradus and G 161-71 in Argus. We also report the first parallax for the planet-hosting star GJ 3470; this allows us to refine the density of its Neptune-mass planet. T-dwarf 2MASS J12590470-4336243, previously thought to lie within 4 pc, is found to be at 7.8 pc, and the M-type star 2MASS J01392170-3936088 joins the ranks of nearby stars as it is found to be within 10 pc. Five stars that are overluminous and/or too red for their spectral types are identified and deserve further study as possible young stars.

TRIGONOMETRIC PARALLAXES AND PROPER MOTIONS OF 134 SOUTHERN LATE M, L, AND T DWARFS FROM THE CARNEGIE ASTROMETRIC PLANET SEARCH PROGRAM

International Nuclear Information System (INIS)

Weinberger, Alycia J.; Boss, Alan P.; Keiser, Sandra A.; Anglada-Escudé, Guillem; Thompson, Ian B.; Burley, Gregory

2016-01-01

We report trigonometric parallaxes for 134 low-mass stars and brown dwarfs, of which 38 have no previously published measurement and 79 more have improved uncertainties. Our survey focused on nearby targets, so 119 are closer than 30 pc. Of the 38 stars with new parallaxes, 14 are within 20 pc and seven are likely brown dwarfs (spectral types later than L0). These parallaxes are useful for studies of kinematics, multiplicity, and spectrophotometric calibration. Two objects with new parallaxes are confirmed as young stars with membership in nearby young moving groups: LP 870-65 in AB Doradus and G 161-71 in Argus. We also report the first parallax for the planet-hosting star GJ 3470; this allows us to refine the density of its Neptune-mass planet. T-dwarf 2MASS J12590470-4336243, previously thought to lie within 4 pc, is found to be at 7.8 pc, and the M-type star 2MASS J01392170-3936088 joins the ranks of nearby stars as it is found to be within 10 pc. Five stars that are overluminous and/or too red for their spectral types are identified and deserve further study as possible young stars.

ARSTEC, Nonlinear Optimization Program Using Random Search Method

International Nuclear Information System (INIS)

Rasmuson, D. M.; Marshall, N. H.

1979-01-01

1 - Description of problem or function: The ARSTEC program was written to solve nonlinear, mixed integer, optimization problems. An example of such a problem in the nuclear industry is the allocation of redundant parts in the design of a nuclear power plant to minimize plant unavailability. 2 - Method of solution: The technique used in ARSTEC is the adaptive random search method. The search is started from an arbitrary point in the search region and every time a point that improves the objective function is found, the search region is centered at that new point. 3 - Restrictions on the complexity of the problem: Presently, the maximum number of independent variables allowed is 10. This can be changed by increasing the dimension of the arrays

Mercury - Introduction to an end-member planet

International Nuclear Information System (INIS)

Chapman, C.R.

1988-01-01

This chapter introduces the major themes of this book. In many ways, Mercury is an extreme planet, and thus it provides a unique benchmark for testing our theories about the origin and evolution of other (particularly terrestrial) planets. Emphasis is given to synthesizing and critiquing the book's chapters on the planet's origin, its metal-rich composition, its thermal and geophysical evolution, and its cratering history; these topics are complex and controversial, and this book contains a variety of new perspectives on them. Mercury's geology, atmosphere and magnetosphere are discussed more briefly. The study of Mercury is placed in its historical context and in the context of the spacecraft exploration program, both past and future

Three new massive companions in the planet-brown dwarf boundary detected with SOPHIE

Directory of Open Access Journals (Sweden)

Santerne A.

2011-02-01

Full Text Available We report the detection of three new massive companions to mainsequence stars based on precise radial velocities obtained with the SOPHIE spectrograph, as part of an ongoing programme to search for extrasolar planets. The minimum masses of the detected companions range from around 16 Mjup to around 60 Mjup, and therefore lie at both sides of the boundary between massive extrasolar planets and brown dwarves.

THE PECULIAR SOLAR COMPOSITION AND ITS POSSIBLE RELATION TO PLANET FORMATION

International Nuclear Information System (INIS)

Melendez, J.; Asplund, M.; Gustafsson, B.; Yong, D.

2009-01-01

We have conducted a differential elemental abundance analysis of unprecedented accuracy (∼0.01 dex) of the Sun relative to 11 solar twins from the Hipparcos catalog and 10 solar analogs from planet searches. We find that the Sun shows a characteristic signature with a ∼20% depletion of refractory elements relative to the volatile elements in comparison with the solar twins. The abundance differences correlate strongly with the condensation temperatures of the elements. This peculiarity also holds in comparisons with solar analogs known to have close-in giant planets while the majority of solar analogs found not to have such giant planets in radial velocity monitoring show the solar abundance pattern. We discuss various explanations for this peculiarity, including the possibility that the differences in abundance patterns are related to the formation of planetary systems like our own, in particular to the existence of terrestrial planets.

Habitability in the Solar System and on Extrasolar Planets and Moons

Science.gov (United States)

McKay, Christopher P.

2015-01-01

The criteria for a habitable world initially was based on Earth and centered around liquid water on the surface, warmed by a Sun-like star. The moons of the outer Solar System, principally Europa and Enceladus, have demonstrated that liquid water can exist below the surface warmed by tidal forces from a giant planet. Titan demonstrates that surface liquids other than water - liquid methane/ethane - may be common on other worlds. Considering the numerous extrasolar planets so far discovered and the prospect of discovering extrasolar moons it is timely to reconsider the possibilities for habitability in the Solar System and on extrasolar planets and moons and enumerate the attributes and search methods for detecting habitable worlds and evidence of life.

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

The MAO NASU Plate Archive: ``observations in the past'' of minor planets

Science.gov (United States)

Sergeeva, T. P.; Golovnya, V. V.; Sergeev, A. V.

2005-06-01

The Plate Archive of the Main Astronomical Observatory of the National Academy of Sciences of Ukraine (MAO NASU) includes 20 thousands of direct sky area plates, which have been taken for various astronomical projects during the period of about 50 years. Those plates contain more then hundred thousand images of minor planets with magnitude up to 16.7m. About 10% of minor planets, which may be found on our archive plates were firstly discovered after the time when plates have been taken. So, we can rediscovery them due to the so-called ``observations in the past''. In the paper the criteria for choose of objects and methods of their search, identification, and determination of their position are discussed. First results of the search for potentially hazardous asteroids in the MAO plate archive are presented.

Searching for Strange Quark Matter Objects in Exoplanets

Energy Technology Data Exchange (ETDEWEB)

Huang, Y. F.; Yu, Y. B., E-mail: hyf@nju.edu.cn [Department of Astronomy, School of Astronomy and Space Science, Nanjing University, Nanjing 210023 (China)

2017-10-20

The true ground state of hadronic matter may be strange quark matter (SQM). Consequently, observed pulsars may actually be strange quark stars, but not neutron stars. However, proving or disproving the SQM hypothesis still remains a difficult problem to solve due to the similarity between the macroscopical characteristics of strange quark stars and neutron stars. Here, we propose a hopeful method to probe the existence of SQM. In the framework of the SQM hypothesis, strange quark dwarfs and even strange quark planets can also stably exist. Noting that SQM planets will not be tidally disrupted even when they get very close to their host stars due to their extreme compactness, we argue that we could identify SQM planets by searching for very close-in planets among extrasolar planetary systems. Especially, we should keep our eyes on possible pulsar planets with orbital radius less than ∼5.6 × 10{sup 10} cm and period less than ∼6100 s. A thorough search in the currently detected ∼2950 exoplanets around normal main-sequence stars has failed to identify any stable close-in objects that meet the SQM criteria, i.e., lying in the tidal disruption region for normal matter planets. However, the pulsar planet PSR J1719-1438B, with an orbital radius of ∼6 × 10{sup 10} cm and orbital period of 7837 s, is, encouragingly, found to be a good candidate.

A survey for very short-period planets in the Kepler data

Energy Technology Data Exchange (ETDEWEB)

Jackson, Brian; Stark, Christopher C.; Chambers, John [Carnegie Institution for Science, 5241 Broad Branch Road NW, Washington, DC 20015 (United States); Adams, Elisabeth R. [Planetary Science Institute, 1700 East Fort Lowell, Suite 106, Tucson, AZ 85719 (United States); Deming, Drake, E-mail: bjackson@dtm.ciw.edu [Department of Astronomy, University of Maryland at College Park, College Park, MD 20742 (United States)

2013-12-20

We conducted a search for very short-period transiting objects in the publicly available Kepler data set. Our preliminary survey has revealed four planetary candidates, all with orbital periods less than 12 hr. We have analyzed the data for these candidates using photometric models that include transit light curves, ellipsoidal variations, and secondary eclipses to constrain the candidates' radii, masses, and effective temperatures. Even with masses of only a few Earth masses, the candidates' short periods mean that they may induce stellar radial velocity signals (a few m s{sup –1}) detectable by currently operating facilities. The origins of such short-period planets are unclear, but we discuss the possibility that they may be the remnants of disrupted hot Jupiters. Whatever their origins, if confirmed as planets, these candidates would be among the shortest-period planets ever discovered. Such planets would be particularly amenable to discovery by the planned TESS mission.

A survey for very short-period planets in the Kepler data

International Nuclear Information System (INIS)

Jackson, Brian; Stark, Christopher C.; Chambers, John; Adams, Elisabeth R.; Deming, Drake

2013-01-01

We conducted a search for very short-period transiting objects in the publicly available Kepler data set. Our preliminary survey has revealed four planetary candidates, all with orbital periods less than 12 hr. We have analyzed the data for these candidates using photometric models that include transit light curves, ellipsoidal variations, and secondary eclipses to constrain the candidates' radii, masses, and effective temperatures. Even with masses of only a few Earth masses, the candidates' short periods mean that they may induce stellar radial velocity signals (a few m s –1 ) detectable by currently operating facilities. The origins of such short-period planets are unclear, but we discuss the possibility that they may be the remnants of disrupted hot Jupiters. Whatever their origins, if confirmed as planets, these candidates would be among the shortest-period planets ever discovered. Such planets would be particularly amenable to discovery by the planned TESS mission.

EFFECTS OF DYNAMICAL EVOLUTION OF GIANT PLANETS ON SURVIVAL OF TERRESTRIAL PLANETS

International Nuclear Information System (INIS)

Matsumura, Soko; Ida, Shigeru; Nagasawa, Makiko

2013-01-01

The orbital distributions of currently observed extrasolar giant planets allow marginally stable orbits for hypothetical, terrestrial planets. In this paper, we propose that many of these systems may not have additional planets on these ''stable'' orbits, since past dynamical instability among giant planets could have removed them. We numerically investigate the effects of early evolution of multiple giant planets on the orbital stability of the inner, sub-Neptune-like planets which are modeled as test particles, and determine their dynamically unstable region. Previous studies have shown that the majority of such test particles are ejected out of the system as a result of close encounters with giant planets. Here, we show that secular perturbations from giant planets can remove test particles at least down to 10 times smaller than their minimum pericenter distance. Our results indicate that, unless the dynamical instability among giant planets is either absent or quiet like planet-planet collisions, most test particles down to ∼0.1 AU within the orbits of giant planets at a few AU may be gone. In fact, out of ∼30% of survived test particles, about three quarters belong to the planet-planet collision cases. We find a good agreement between our numerical results and the secular theory, and present a semi-analytical formula which estimates the dynamically unstable region of the test particles just from the evolution of giant planets. Finally, our numerical results agree well with the observations, and also predict the existence of hot rocky planets in eccentric giant planet systems.

Finding A Planet Through the Dust

Science.gov (United States)

Kohler, Susanna

2018-05-01

Finding planets in the crowded galactic center is a difficult task, but infrared microlensing surveys give us a fighting chance! Preliminary results from such a study have already revealed a new exoplanet lurking in the dust of the galactic bulge.Detection BiasesUKIRT-2017 microlensing survey fields (blue), plotted over a map showing the galactic-plane dust extinction. The location of the newly discovered giant planet is marked with blue crosshairs. [Shvartzvald et al. 2018]Most exoplanets weve uncovered thus far were found either via transits dips in a stars light as the planet passes in front of its host star or via radial velocity wobbles of the star as the orbiting planet tugs on it. These techniques, while highly effective, introduce a selection bias in the types of exoplanets we detect: both methods tend to favor discovery of close-in, large planets orbiting small stars; these systems produce the most easily measurable signals on short timescales.For this reason, microlensing surveys for exoplanets have something new to add to the field.Search for a LensIn gravitational microlensing, we observe a background star as it is briefly magnified by a passing foreground star acting as a lens. If that foreground star hosts a planet, we observe a characteristic shape in the observed brightening of the background star, and the properties of that shape can reveal information about the foreground planet.A diagram of how planets are detected via gravitational microlensing. The detectable planet is in orbit around the foreground lens star. [NASA]This technique for planet detection is unique in its ability to explore untapped regions of exoplanet parameter space with microlensing, we can survey for planets around all different types of stars (rather than primarily small, dim ones), planets of all masses near the further-out snowlines where gas and ice giants are likely to form, and even free-floating planets.In a new study led by a Yossi Shvartzvald, a NASA postdoctoral

Automatic programming via iterated local search for dynamic job shop scheduling.

Science.gov (United States)

Nguyen, Su; Zhang, Mengjie; Johnston, Mark; Tan, Kay Chen

2015-01-01

Dispatching rules have been commonly used in practice for making sequencing and scheduling decisions. Due to specific characteristics of each manufacturing system, there is no universal dispatching rule that can dominate in all situations. Therefore, it is important to design specialized dispatching rules to enhance the scheduling performance for each manufacturing environment. Evolutionary computation approaches such as tree-based genetic programming (TGP) and gene expression programming (GEP) have been proposed to facilitate the design task through automatic design of dispatching rules. However, these methods are still limited by their high computational cost and low exploitation ability. To overcome this problem, we develop a new approach to automatic programming via iterated local search (APRILS) for dynamic job shop scheduling. The key idea of APRILS is to perform multiple local searches started with programs modified from the best obtained programs so far. The experiments show that APRILS outperforms TGP and GEP in most simulation scenarios in terms of effectiveness and efficiency. The analysis also shows that programs generated by APRILS are more compact than those obtained by genetic programming. An investigation of the behavior of APRILS suggests that the good performance of APRILS comes from the balance between exploration and exploitation in its search mechanism.

High-resolution spectroscopic search for the thermal emission of the extrasolar planet HD 217107 b

OpenAIRE

Cubillos, Patricio E.; Rojo, Patricio; Fortney, Jonathan J.

2011-01-01

We analyzed the combined near-infrared spectrum of a star-planet system with thermal emission atmospheric models, based on the composition and physical parameters of the system. The main objective of this work is to obtain the inclination of the orbit, the mass of the exoplanet, and the planet-to-star flux ratio. We present the results of our routines on the planetary system HD 217107, which was observed with the high-resolution spectrograph Phoenix at 2.14 microns. We revisited and tuned a c...

Kepler Planet Detection Metrics: Window and One-Sigma Depth Functions for Data Release 25

Science.gov (United States)

Burke, Christopher J.; Catanzarite, Joseph

2017-01-01

This document describes the window and one-sigma depth functions relevant to the Transiting Planet Search (TPS) algorithm in the Kepler pipeline (Jenkins 2002; Jenkins et al. 2017). The window function specifies the fraction of unique orbital ephemeris epochs over which three transits are observable as a function of orbital period. In this context, the epoch and orbital period, together, comprise the ephemeris of an orbiting companion, and ephemerides with the same period are considered equivalent if their epochs differ by an integer multiple of the period. The one-sigma depth function specifies the depth of a signal (in ppm) for a given light curve that results in a one-sigma detection of a transit signature as a function of orbital period when averaged over all unique orbital ephemerides. These planet detection metrics quantify the ability of TPS to detect a transiting planet signature on a star-by-star basis. They are uniquely applicable to a specific Kepler data release, since they are dependent on the details of the light curves searched and the functionality of the TPS algorithm used to perform the search. This document describes the window and one-sigma depth functions relevant to Kepler Data Release 25 (DR25), where the data were processed (Thompson et al. 2016) and searched (Twicken et al. 2016) with the SOC 9.3 pipeline. In Section 4, we describe significant differences from those reported in Kepler Data Release 24 (Burke Seader 2016) and document our verification method.

Monte Carlo Methods to Establish Confidence in Planets Discovered by Transit Photometry

Science.gov (United States)

Jenkins, J. M.; Caldwell, D. A.

2000-12-01

With the astonishing discovery of about a dozen super giant short-period (attention on the problem of assessing the significance of a candidate transit signature. There are two fundamental quantities of interest required to establish the confidence in a planetary candidate. These are: 1) the equivalent number of independent statistical tests conducted in searching the light curve of one star for transiting planets over a given range of periods, and 2) the characteristics of the observation noise for the light curve in question. The latter quantity determines the false alarm rate for a single test for that particular star as a function of the detection threshold. The former quantity, together with the total number of target stars in the observing program, dictate the requisite single-test false alarm rate based on the acceptable total number of false alarms. The methods described do not make any presumptions about the distribution of the observational noise. In addition they either provide conservative results for non-white noise or take the correlation structure of the noise into account. The results of this paper show that transit photometry is a promising method for detecting planets even in the presence of colored, non-Gaussian noise and with the required large number of target stars (>100,000 stars in the case of the Kepler Mission) for the small geometric probability of transit alignment. Support for this work was received from NASA's Discovery Program.

Magnetometer instrument team studies for the definition phase of the outer planets grand tour

Science.gov (United States)

Coleman, P. J., Jr.

1972-01-01

The objectives of magnetic field investigations on missions to the outer planets were defined as well as an instrumentation system, a program of studies and instrument development tasks was proposed for the mission definition phase of the Outer Planets Grand Tour project. A report on the status of this program is given. Requirements were also established for the spacecraft and the mission which would insure their compatibility with the magnetic field investigation proposed for the outer planets missions and developed figures of merit for encounter trajectories. The spacecraft-instrumentation interface and the on-board data handling system were defined in various reports by the Project Team and in the reports by the Science Steering Group. The defining program for exploring the outer planets within the more restrictive constraints of the Mariner Jupiter-Saturn project included defining a limited magnetic field investigation.

Planet Candidate Validation in K2 Crowded Fields

Science.gov (United States)

Rampalli, Rayna; Vanderburg, Andrew; Latham, David; Quinn, Samuel

2018-01-01

In just three years, the K2 mission has yielded some remarkable outcomes with the discovery of over 100 confirmed planets and 500 reported planet candidates to be validated. One challenge with this mission is the search for planets located in star-crowded regions. Campaign 13 is one such example, located towards the galactic plane in the constellation of Taurus. We subject the potential planetary candidates to a validation process involving spectroscopy to derive certain stellar parameters. Seeing-limited on/off imaging follow-up is also utilized in order to rule out false positives due to nearby eclipsing binaries. Using Markov chain Monte Carlo analysis, the best-fit parameters for each candidate are generated. These will be suitable for finding a candidate’s false positive probability through methods including feeding such parameters into the Validation of Exoplanet Signals using a Probabilistic Algorithm (VESPA). These techniques and results serve as important tools for conducting candidate validation and follow-up observations for space-based missions such as the upcoming TESS mission since TESS’s large camera pixels resemble K2’s star-crowded fields.

The Fate of Exomoons when Planets Scatter

Science.gov (United States)

Kohler, Susanna

2018-03-01

orbits similar to Jupiters Galilean satellites (i.e., orbiting at a distance of less than 4% of their host planets Hill radius) have a 2040% chance of survival.Moon initial semimajor axis vs. moon survival rate. Three of Jupiters Galilean moons are shown for reference. [Hong et al. 2018]Free-Floating MoonsAn intriguing consequence of Hong and collaborators results is the prediction of a population of free-floating exomoons that were ejected from solar systems during planetplanet scattering and now wander through the universe alone. According to the authors models, there may be as many of these free-floating exomoons as there are stars in the universe!Future surveys that search for objects using gravitational microlensing like that planned with the Wide-Field Infrared Survey Telescope (WFIRST) may be able to detect such objects down to masses of a tenth of an Earth mass. In the meantime, were a little closer to understanding the complex dynamics of early solar systems.CitationYu-Cian Hong et al 2018 ApJ 852 85. doi:10.3847/1538-4357/aaa0db

High-resolution multi-band imaging for validation and characterization of small Kepler planets

International Nuclear Information System (INIS)

Everett, Mark E.; Silva, David R.; Barclay, Thomas; Howell, Steve B.; Ciardi, David R.; Horch, Elliott P.; Crepp, Justin R.

2015-01-01

High-resolution ground-based optical speckle and near-infrared adaptive optics images are taken to search for stars in close angular proximity to host stars of candidate planets identified by the NASA Kepler Mission. Neighboring stars are a potential source of false positive signals. These stars also blend into Kepler light curves, affecting estimated planet properties, and are important for an understanding of planets in multiple star systems. Deep images with high angular resolution help to validate candidate planets by excluding potential background eclipsing binaries as the source of the transit signals. A study of 18 Kepler Object of Interest stars hosting a total of 28 candidate and validated planets is presented. Validation levels are determined for 18 planets against the likelihood of a false positive from a background eclipsing binary. Most of these are validated at the 99% level or higher, including five newly validated planets in two systems: Kepler-430 and Kepler-431. The stellar properties of the candidate host stars are determined by supplementing existing literature values with new spectroscopic characterizations. Close neighbors of seven of these stars are examined using multi-wavelength photometry to determine their nature and influence on the candidate planet properties. Most of the close neighbors appear to be gravitationally bound secondaries, while a few are best explained as closely co-aligned field stars. Revised planet properties are derived for each candidate and validated planet, including cases where the close neighbors are the potential host stars.

ALMOST ALL OF KEPLER'S MULTIPLE-PLANET CANDIDATES ARE PLANETS

Energy Technology Data Exchange (ETDEWEB)

Lissauer, Jack J.; Rowe, Jason F.; Bryson, Stephen T.; Howell, Steve B.; Jenkins, Jon M.; Kinemuchi, Karen; Koch, David G. [NASA Ames Research Center, Moffett Field, CA 94035 (United States); Marcy, Geoffrey W. [Astronomy Department, University of California, Berkeley, CA 94720 (United States); Adams, Elisabeth; Fressin, Francois; Geary, John; Holman, Matthew J.; Ragozzine, Darin [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Buchhave, Lars A. [Niels Bohr Institute, University of Copenhagen, DK-2100, Copenhagen (Denmark); Ciardi, David R. [Exoplanet Science Institute/Caltech, Pasadena, CA 91125 (United States); Cochran, William D. [Department of Astronomy, University of Texas, Austin, TX 78712 (United States); Fabrycky, Daniel C. [Department of Astronomy and Astrophysics, University of California, Santa Cruz, CA 95064 (United States); Ford, Eric B.; Morehead, Robert C. [University of Florida, 211 Bryant Space Science Center, Gainesville, FL 32611 (United States); Gilliland, Ronald L., E-mail: Jack.Lissauer@nasa.gov [Space Telescope Science Institute, Baltimore, MD 21218 (United States); and others

2012-05-10

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 detectable planets tend to come in systems and/or if the orbital planes of planets encircling the same star are correlated. There are more than one hundred times as many Kepler planet candidates in multi-candidate systems as would be predicted from a random distribution of candidates, implying that the vast majority are true planets. Most of these multis are multiple-planet systems orbiting the Kepler target star, but there are likely cases where (1) the planetary system orbits a fainter star, and the planets are thus significantly larger than has been estimated, or (2) the planets orbit different stars within a binary/multiple star system. We use the low overall false-positive rate among Kepler multis, together with analysis of Kepler spacecraft and ground-based data, to validate the closely packed Kepler-33 planetary system, which orbits a star that has evolved somewhat off of the main sequence. Kepler-33 hosts five transiting planets, with periods ranging from 5.67 to 41 days.

Observsational Planet Formation

Science.gov (United States)

Dong, Ruobing; Zhu, Zhaohuan; Fung, Jeffrey

2017-06-01

Planets form in gaseous protoplanetary disks surrounding newborn stars. As such, the most direct way to learn how they form from observations, is to directly watch them forming in disks. In the past, this was very difficult due to a lack of observational capabilities; as such, planet formation was largely a subject of pure theoretical astrophysics. Now, thanks to a fleet of new instruments with unprecedented resolving power that have come online recently, we have just started to unveil features in resolve images of protoplanetary disks, such as gaps and spiral arms, that are most likely associated with embedded (unseen) planets. By comparing observations with theoretical models of planet-disk interactions, the masses and orbits of these still forming planets may be constrained. Such planets may help us to directly test various planet formation models. This marks the onset of a new field — observational planet formation. I will introduce the current status of this field.

Kuiper belt analogues in nearby M-type planet-host systems

Science.gov (United States)

Kennedy, G. M.; Bryden, G.; Ardila, D.; Eiroa, C.; Lestrade, J.-F.; Marshall, J. P.; Matthews, B. C.; Moro-Martin, A.; Wyatt, M. C.

2018-06-01

We present the results of a Herschel survey of 21 late-type stars that host planets discovered by the radial velocity technique. The aims were to discover new discs in these systems and to search for any correlation between planet presence and disc properties. In addition to the known disc around GJ 581, we report the discovery of two new discs, in the GJ 433 and GJ 649 systems. Our sample therefore yields a disc detection rate of 14 per cent, higher than the detection rate of 1.2 per cent among our control sample of DEBRIS M-type stars with 98 per cent confidence. Further analysis however shows that the disc sensitivity in the control sample is about a factor of two lower in fractional luminosity than for our survey, lowering the significance of any correlation between planet presence and disc brightness below 98 per cent. In terms of their specific architectures, the disc around GJ 433 lies at a radius somewhere between 1 and 30 au. The disc around GJ 649 lies somewhere between 6 and 30 au, but is marginally resolved and appears more consistent with an edge-on inclination. In both cases the discs probably lie well beyond where the known planets reside (0.06-1.1 au), but the lack of radial velocity sensitivity at larger separations allows for unseen Saturn-mass planets to orbit out to ˜5 au, and more massive planets beyond 5 au. The layout of these M-type systems appears similar to Sun-like star + disc systems with low-mass planets.

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.

Maximizing the TESS Mission’s Yield of Long-Period Planets

Science.gov (United States)

Dragomir, Diana; Gaudi, B. Scott; Villanueva, Steven; Crossfield, Ian; Huang, Xu; Ribas, Ignasi; Quinn, Samuel

2018-01-01

The upcoming TESS mission will discover thousands of transiting planets around bright stars. However, during its primary mission the satellite will observe most of the sky for just 27 days (and for at most one year even in its continuous viewing zones near the ecliptic poles), thus limiting the mission’s yield of long-period planets that show three or more transits in the TESS light curves. By also pursuing single- and double-transit events, we can increase by several hundred the number of planets with periods longer than 10 days that TESS will discover. I will show how strategic planning and the judicious use of follow-up observations can confirm these planets and refine their ephemerides. Through this program, we will generate a sample of long-period planets transiting bright stars that are ripe for detailed characterization studies such as mass measurements and atmospheric observations. In turn, these studies will provide important constraints on the composition and formation of long-period planets.

THE FIRST PLANETS: THE CRITICAL METALLICITY FOR PLANET FORMATION

International Nuclear Information System (INIS)

Johnson, Jarrett L.; Li Hui

2012-01-01

A rapidly growing body of observational results suggests that planet formation takes place preferentially at high metallicity. In the core accretion model of planet formation this is expected because heavy elements are needed to form the dust grains which settle into the midplane of the protoplanetary disk and coagulate to form the planetesimals from which planetary cores are assembled. As well, there is observational evidence that the lifetimes of circumstellar disks are shorter at lower metallicities, likely due to greater susceptibility to photoevaporation. Here we estimate the minimum metallicity for planet formation, by comparing the timescale for dust grain growth and settling to that for disk photoevaporation. For a wide range of circumstellar disk models and dust grain properties, we find that the critical metallicity above which planets can form is a function of the distance r at which the planet orbits its host star. With the iron abundance relative to that of the Sun [Fe/H] as a proxy for the metallicity, we estimate a lower limit for the critical abundance for planet formation of [Fe/H] crit ≅ –1.5 + log (r/1 AU), where an astronomical unit (AU) is the distance between the Earth and the Sun. This prediction is in agreement with the available observational data, and carries implications for the properties of the first planets and for the emergence of life in the early universe. In particular, it implies that the first Earth-like planets likely formed from circumstellar disks with metallicities Z ∼> 0.1 Z ☉ . If planets are found to orbit stars with metallicities below the critical metallicity, this may be a strong challenge to the core accretion model.

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.

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.

Extrasolar planets: constraints for planet formation models.

Science.gov (United States)

Santos, Nuno C; Benz, Willy; Mayor, Michel

2005-10-14

Since 1995, more than 150 extrasolar planets have been discovered, most of them in orbits quite different from those of the giant planets in our own solar system. The number of discovered extrasolar planets demonstrates that planetary systems are common but also that they may possess a large variety of properties. As the number of detections grows, statistical studies of the properties of exoplanets and their host stars can be conducted to unravel some of the key physical and chemical processes leading to the formation of planetary systems.

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

CANDIDATE PLANETS IN THE HABITABLE ZONES OF KEPLER STARS

International Nuclear Information System (INIS)

Gaidos, Eric

2013-01-01

A key goal of the Kepler mission is the discovery of Earth-size transiting planets in ''habitable zones'' where stellar irradiance maintains a temperate climate on an Earth-like planet. Robust estimates of planet radius and irradiance require accurate stellar parameters, but most Kepler systems are faint, making spectroscopy difficult and prioritization of targets desirable. The parameters of 2035 host stars were estimated by Bayesian analysis and the probabilities p HZ that 2738 candidate or confirmed planets orbit in the habitable zone were calculated. Dartmouth Stellar Evolution Program models were compared to photometry from the Kepler Input Catalog, priors for stellar mass, age, metallicity and distance, and planet transit duration. The analysis yielded probability density functions for calculating confidence intervals of planet radius and stellar irradiance, as well as p HZ . Sixty-two planets have p HZ > 0.5 and a most probable stellar irradiance within habitable zone limits. Fourteen of these have radii less than twice the Earth; the objects most resembling Earth in terms of radius and irradiance are KOIs 2626.01 and 3010.01, which orbit late K/M-type dwarf stars. The fraction of Kepler dwarf stars with Earth-size planets in the habitable zone (η ⊕ ) is 0.46, with a 95% confidence interval of 0.31-0.64. Parallaxes from the Gaia mission will reduce uncertainties by more than a factor of five and permit definitive assignments of transiting planets to the habitable zones of Kepler stars.

Removing Activity-Related Radial Velocity Noise to Improve Extrasolar Planet Searches

Science.gov (United States)

Saar, Steven; Lindstrom, David M. (Technical Monitor)

2004-01-01

We have made significant progress towards the proposal goals of understanding the causes and effects of magnetic activity-induced radial velocity (v_r) jitter and developing methods for correcting it. In the process, we have also made some significant discoveries in the fields of planet-induced stellar activity, planet detection methods, M dwarf convection, starspot properties, and magnetic dynamo cycles. We have obtained super high resolution (R approximately 200,000), high S / N (greater than 300) echelle study of joint line bisector and radial velocity variations using the McDonald 2-D coude. A long observing run in October 2002 in particular was quite successful (8 clear nights). We now have close to three years of data, which begins to sample a good fraction of the magnetic cycle timescales for some of our targets (e.g., kappa Ceti; P_cyc = 5.6 yrs). This will be very helpful in unraveling the complex relationships between plage and radial velocity (v-r) changes which we have uncovered. Preliminary analysis (Saar et al. 2003) of the data in hand, reveals correlations between median line bisector displacement and v_r. The correlation appears to be specific the the particular star being considered, probably since it is a function of both spectral type and rotation rate. Further analysis and interpretation will be in the context of evolving plage models and is in progress.

Pathways Towards Habitable Planets: Capabilities of the James Webb Space Telescope

Science.gov (United States)

Clampin, Mark

2009-01-01

The James Webb Space Telescope (JWST) is a large aperture (6.5 meter), cryogenic space telescope with a suite of near and mid-infrared instruments covering the wavelength range of 0.6 m to 28 m. JWST s primary science goal is to detect and characterize the first galaxies. It will also study the assembly of galaxies, star formation, and the formation of evolution of planetary systems. We also review the expected scientific performance of the observatory for observations of exosolar planets by means of transit photometry and spectroscopy, and direct coronagraphic imaging and address its role in the search for habitable planets.

The Hunt for Planet X New Worlds and the Fate of Pluto

CERN Document Server

Schilling, Govert

2009-01-01

"The Hunt for Planet X is a fascinating tale by one of the world's premier astronomy writers. Govert Schilling is not only scrupulously accurate, he writes beautifully as well." Stephen P. Maran, Author of "Astronomy for Dummies" and Press Officer, American Astronomical Society "The Hunt for Planet X is an adventure story or, more accurately, a series of adventure stories. Schilling tells them well, capturing both the science and the people involved. It starts with the classics: Uranus, Neptune and Pluto; and moves all over the solar system as ground-based astronomers and space scientists pour over measurements and observations to try to understand the worlds around us. Current debates about the Pioneer Anomaly and the definition of what is a planet make the book current as well as a good history." Dr. Louis Friedman, Executive Director, The Planetary Society "This exciting tale of the centuries-old search for new planets in the solar system reads like a thriller. It is an adventure packed with fierce competi...

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.

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.

2012-01-01

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. PMID:22566651

Origins and Destinations: Tracking Planet Composition through Planet Formation Simulations

Science.gov (United States)

Chance, Quadry; Ballard, Sarah

2018-01-01

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 follow-up.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 can 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.

Planet logy : Towards Comparative Planet logy beyond the Solar Earth System

Science.gov (United States)

Khan, A. H.

2011-10-01

Today Scenario planet logy is a very important concept because now days the scientific research finding new and new planets and our work's range becoming too long. In the previous study shows about 10-12 years the research of planet logy now has changed . Few years ago we was talking about Sun planet, Earth planet , Moon ,Mars Jupiter & Venus etc. included but now the time has totally changed the recent studies showed that mono lakes California find the arsenic food use by micro organism that show that our study is very tiny as compare to planet long areas .We have very well known that arsenic is the toxic agent's and the toxic agent's present in the lakes and micro organism developing and life going on it's a unbelievable point for us but nature always play a magical games. In few years ago Aliens was the story no one believe the Aliens origin but now the aliens showed catch by our space craft and shuttle and every one believe that Aliens origin but at the moment's I would like to mention one point's that we have too more work required because our planet logy has a vast field. Most of the time our scientific mission shows that this planet found liquid oxygen ,this planet found hydrogen .I would like to clear that point's that all planet logy depend in to the chemical and these chemical gave the indication of the life but we are not abele to developed the adaptation according to the micro organism . Planet logy compare before study shows that Sun it's a combination of the various gases combination surrounded in a round form and now the central Sun Planets ,moons ,comets and asteroids In other word we can say that Or Sun has a wide range of the physical and Chemical properties in the after the development we can say that all chemical and physical property engaged with a certain environment and form a various contains like asteroids, moon, Comets etc. Few studies shows that other planet life affected to the out living planet .We can assure with the example the life

HUNTING FOR PLANETS IN THE HL TAU DISK

Energy Technology Data Exchange (ETDEWEB)

Testi, L. [ESO, Karl Schwarzschild str. 2, D-85748 Garching bei Muenchen (Germany); Skemer, A.; Bailey, V.; Defrère, D.; Hinz, Ph.; Leisenring, J.; Vaz, A. [Steward Observatory, University of Arizona, 933 N. Cherry Ave., Tucson, AZ 85721 (United States); Henning, Th. [Max Planck Institute for Astronomie, Königstuhl 17, D-69117 Heidelberg (Germany); Esposito, S. [INAF-Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, I-50125 Firenze (Italy); Fontana, A. [INAF-Osservatorio Astronomico di Roma, Monte Porzio (Italy); Marconi, A. [Universitá degli Studi di Firenze, Dipartimento di Fisica e Astronomia, Firenze (Italy); Skrutskie, M. [University of Virginia, 530 McCormick Road, Charlottesville, VA 22904 (United States); Veillet, C., E-mail: ltesti@eso.org [LBT Observatory, University of Arizona, 933 N. Cherry Ave., Tucson, AZ 85721 (United States)

2015-10-20

Recent ALMA images of HL Tau show gaps in the dusty disk that may be caused by planetary bodies. Given the young age of this system, if confirmed, this finding would imply very short timescales for planet formation, probably in a gravitationally unstable disk. To test this scenario, we searched for young planets by means of direct imaging in the L′ band using the Large Binocular Telescope Interferometer mid-infrared camera. At the location of two prominent dips in the dust distribution at ∼70 AU (∼0.″5) from the central star, we reach a contrast level of ∼7.5 mag. We did not detect any point sources at the location of the rings. Using evolutionary models we derive upper limits of ∼10–15 M{sub Jup} at ≤0.5–1 Ma for the possible planets. With these sensitivity limits we should have been able to detect companions sufficiently massive to open full gaps in the disk. The structures detected at millimeter wavelengths could be gaps in the distributions of large grains on the disk midplane caused by planets not massive enough to fully open the gaps. Future ALMA observations of the molecular gas density profile and kinematics as well as higher contrast infrared observations may be able to provide a definitive answer.

HUNTING FOR PLANETS IN THE HL TAU DISK

International Nuclear Information System (INIS)

Testi, L.; Skemer, A.; Bailey, V.; Defrère, D.; Hinz, Ph.; Leisenring, J.; Vaz, A.; Henning, Th.; Esposito, S.; Fontana, A.; Marconi, A.; Skrutskie, M.; Veillet, C.

2015-01-01

Recent ALMA images of HL Tau show gaps in the dusty disk that may be caused by planetary bodies. Given the young age of this system, if confirmed, this finding would imply very short timescales for planet formation, probably in a gravitationally unstable disk. To test this scenario, we searched for young planets by means of direct imaging in the L′ band using the Large Binocular Telescope Interferometer mid-infrared camera. At the location of two prominent dips in the dust distribution at ∼70 AU (∼0.″5) from the central star, we reach a contrast level of ∼7.5 mag. We did not detect any point sources at the location of the rings. Using evolutionary models we derive upper limits of ∼10–15 M Jup at ≤0.5–1 Ma for the possible planets. With these sensitivity limits we should have been able to detect companions sufficiently massive to open full gaps in the disk. The structures detected at millimeter wavelengths could be gaps in the distributions of large grains on the disk midplane caused by planets not massive enough to fully open the gaps. Future ALMA observations of the molecular gas density profile and kinematics as well as higher contrast infrared observations may be able to provide a definitive answer

Source Security Program in the Philippines: a lost source search experience

International Nuclear Information System (INIS)

Romallosa, Kristine M.; Salabit, Maria T.; Caseria, Estrella; Valdezco, Eulinia

2008-01-01

The Philippine Nuclear Research Institute (PNRI), the national agency in the licensing and regulations of radioactive materials in the country, is strengthening its capabilities in the security of radioactive sources. Part of this program is the PNRI's participation in the Regional Security of Radioactive Sources (RSRS) Project of the Australian Nuclear Science and Technology Organization (ANSTO). The project has provided equipment and methods training, assistance in the development of PNRI's own training program and support for actual orphan source search activities. On May 2007, a source search for the two lost Cs-137 level gauges of a steel manufacturing company was conducted by the PNRI and ANSTO. The source search are the: a) Development of instrument and source search training for the team, the National Training Workshop on Orphan Source Searches which was organized and conducted as a result of train-the-trainors fellowship under the RSRS project; and b) Planning and implementation of the lost source search activity. The conduct of the actual search on warehouses, product yard, canals, dust storage, steel making building, scrap yards and nearby junk shops of the steel plant took one week. The week-long search did not find the lost sources. However, naturally occurring radioactive materials identified to be Thorium, were found on sands, bricks and sack piles that are stored and/or generally present in the warehouses, yard and steel making building. The search activity had therefore cleared the facility of the lost source and its corresponding hazards. The NORM found present in the plant's premises on the other hand brought the attention of the management of the needed measures to ensure safety of the staff from possible hazards of these materials. Currently, the course syllabus that was developed is continuously enhanced to accommodate the training needs of the PNRI staff particularly for the emergency response and preparedness. This component of the source

Mars Atmosphere and Volatile EvolutioN (MAVEN) mission's Red Planet program: Bridging the gap in elementary school science through climate studies of Mars

Science.gov (United States)

Wood, E. L.

2012-12-01

Although reading, writing, and math examinations are often conducted early in elementary school, science is not typically tested until 4th or 5th grade. The result is a refocus on the tested topics at the expense of the untested ones, despite that standards exist for each topic at all grades. On a national level, science instruction is relegated to a matter of a few hours per week. A 2007 Education Policy study states that elementary school students spend an average of 178 minutes a week on science while spending 500 minutes on literacy. A recent NSTA report in July of 2011 of elementary and middle school teachers confirms that teachers feel pressured to teach math and literacy at the expense of other programs. In our interaction with elementary teachers, it is also apparent that many are uncomfortable with science concepts. In order for us to successfully address the Next Generation Science Standards, teachers must be able to reconcile all of the different requirements placed on them in a given school day and in a given school environment. A unique way to combat the lack of science instruction at elementary grades is to combine literacy into an integrated science program, thereby increasing the number of science contact hours. The Red Planet: Read, Write, Explore program, developed for the MAVEN mission, is a science, art, and literacy program designed to easily fit into a typical 3rd-5th grade instructional day. Red Planet tackles climate change through Mars' geologic history and makes Mars-Earth comparisons, while encouraging students to reflect on the environmental requirements needed to keep a biological organisms (including humans) happy, healthy, and alive. The Red Planet program is currently being pilot tested at Acres Green Elementary School in Colorado.

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.

THE OCCURRENCE RATE OF EARTH ANALOG PLANETS ORBITING SUN-LIKE STARS

International Nuclear Information System (INIS)

Catanzarite, Joseph; Shao, Michael

2011-01-01

Kepler is a space telescope that searches Sun-like stars for planets. Its major goal is to determine η Earth , the fraction of Sun-like stars that have planets like Earth. When a planet 'transits' or moves in front of a star, Kepler can measure the concomitant dimming of the starlight. From analysis of the first four months of those measurements for over 150,000 stars, Kepler's Science Team has determined sizes, surface temperatures, orbit sizes, and periods for over a thousand new planet candidates. In this paper, we characterize the period probability distribution function of the super-Earth and Neptune planet candidates with periods up to 132 days, and find three distinct period regimes. For candidates with periods below 3 days, the density increases sharply with increasing period; for periods between 3 and 30 days, the density rises more gradually with increasing period, and for periods longer than 30 days, the density drops gradually with increasing period. We estimate that 1%-3% of stars like the Sun are expected to have Earth analog planets, based on the Kepler data release of 2011 February. This estimate of η Earth is based on extrapolation from a fiducial subsample of the Kepler planet candidates that we chose to be nominally 'complete' (i.e., no missed detections) to the realm of the Earth-like planets, by means of simple power-law models. The accuracy of the extrapolation will improve as more data from the Kepler mission are folded in. Accurate knowledge of η Earth is essential for the planning of future missions that will image and take spectra of Earth-like planets. Our result that Earths are relatively scarce means that a substantial effort will be needed to identify suitable target stars prior to these future missions.

PLANET-PLANET SCATTERING IN PLANETESIMAL DISKS. II. PREDICTIONS FOR OUTER EXTRASOLAR PLANETARY SYSTEMS

International Nuclear Information System (INIS)

Raymond, Sean N.; Armitage, Philip J.; Gorelick, Noel

2010-01-01

We develop an idealized dynamical model to predict the typical properties of outer extrasolar planetary systems, at radii comparable to the Jupiter-to-Neptune region of the solar system. The model is based upon the hypothesis that dynamical evolution in outer planetary systems is controlled by a combination of planet-planet scattering and planetary interactions with an exterior disk of small bodies ('planetesimals'). Our results are based on 5000 long duration N-body simulations that follow the evolution of three planets from a few to 10 AU, together with a planetesimal disk containing 50 M + from 10 to 20 AU. For large planet masses (M ∼> M Sat ), the model recovers the observed eccentricity distribution of extrasolar planets. For lower-mass planets, the range of outcomes in models with disks is far greater than that which is seen in isolated planet-planet scattering. Common outcomes include strong scattering among massive planets, sudden jumps in eccentricity due to resonance crossings driven by divergent migration, and re-circularization of scattered low-mass planets in the outer disk. We present the distributions of the eccentricity and inclination that result, and discuss how they vary with planet mass and initial system architecture. In agreement with other studies, we find that the currently observed eccentricity distribution (derived primarily from planets at a ∼ -1 and periods in excess of 10 years will provide constraints on this regime. Finally, we present an analysis of the predicted separation of planets in two-planet systems, and of the population of planets in mean-motion resonances (MMRs). We show that, if there are systems with ∼ Jupiter-mass planets that avoid close encounters, the planetesimal disk acts as a damping mechanism and populates MMRs at a very high rate (50%-80%). In many cases, resonant chains (in particular the 4:2:1 Laplace resonance) are set up among all three planets. We expect such resonant chains to be common among massive

K2-106, a system containing a metal-rich planet and a planet of lower density

Science.gov (United States)

Guenther, E. W.; Barragán, O.; Dai, F.; Gandolfi, D.; Hirano, T.; Fridlund, M.; Fossati, L.; Chau, A.; Helled, R.; Korth, J.; Prieto-Arranz, J.; Nespral, D.; Antoniciello, G.; Deeg, H.; Hjorth, M.; Grziwa, S.; Albrecht, S.; Hatzes, A. P.; Rauer, H.; Csizmadia, Sz.; Smith, A. M. S.; Cabrera, J.; Narita, N.; Arriagada, P.; Burt, J.; Butler, R. P.; Cochran, W. D.; Crane, J. D.; Eigmüller, Ph.; Erikson, A.; Johnson, J. A.; Kiilerich, A.; Kubyshkina, D.; Palle, E.; Persson, C. M.; Pätzold, M.; Sabotta, S.; Sato, B.; Shectman, St. A.; Teske, J. K.; Thompson, I. B.; Van Eylen, V.; Nowak, G.; Vanderburg, A.; Winn, J. N.; Wittenmyer, R. A.

2017-12-01

Aims: Planets in the mass range from 2 to 15 M⊕ are very diverse. Some of them have low densities, while others are very dense. By measuring the masses and radii, the mean densities, structure, and composition of the planets are constrained. These parameters also give us important information about their formation and evolution, and about possible processes for atmospheric loss. Methods: We determined the masses, radii, and mean densities for the two transiting planets orbiting K2-106. The inner planet has an ultra-short period of 0.57 days. The period of the outer planet is 13.3 days. Results: Although the two planets have similar masses, their densities are very different. For K2-106b we derive Mb=8.36-0.94+0.96 M⊕, Rb = 1.52 ± 0.16 R⊕, and a high density of 13.1-3.6+5.4 g cm-3. For K2-106c, we find Mc=5.8-3.0+3.3 M⊕, Rc=2.50-0.26+0.27 R⊕ and a relatively low density of 2.0-1.1+1.6 g cm-3. Conclusions: Since the system contains two planets of almost the same mass, but different distances from the host star, it is an excellent laboratory to study atmospheric escape. In agreement with the theory of atmospheric-loss processes, it is likely that the outer planet has a hydrogen-dominated atmosphere. The mass and radius of the inner planet is in agreement with theoretical models predicting an iron core containing 80-30+20% of its mass. Such a high metal content is surprising, particularly given that the star has an ordinary (solar) metal abundance. We discuss various possible formation scenarios for this unusual planet. The results are partly based on observations obtained at the European Southern Observatory at Paranal, Chile in program 098.C-0860(A). This paper includes data gathered with the 6.5 m Magellan Telescopes located at Las Campanas Observatory, Chile. The article is also partly based on observations with the TNG, NOT. This work has also made use of data from the European Space Agency (ESA) mission Gaia (http

Visual Fashion-Product Search at SK Planet

OpenAIRE

Kim, Taewan; Kim, Seyeong; Na, Sangil; Kim, Hayoon; Kim, Moonki; Jeon, Byoung-Ki

2016-01-01

We build a large-scale visual search system which finds similar product images given a fashion item. Defining similarity among arbitrary fashion-products is still remains a challenging problem, even there is no exact ground-truth. To resolve this problem, we define more than 90 fashion-related attributes, and combination of these attributes can represent thousands of unique fashion-styles. The fashion-attributes are one of the ingredients to define semantic similarity among fashion-product im...

THE GEMINI/NICI PLANET-FINDING CAMPAIGN: THE FREQUENCY OF PLANETS AROUND YOUNG MOVING GROUP STARS

Energy Technology Data Exchange (ETDEWEB)

Biller, Beth A.; Ftaclas, Christ [Max-Planck-Institut für Astronomie, Königstuhl 17, D-69115 Heidelberg (Germany); Liu, Michael C.; Wahhaj, Zahed; Nielsen, Eric L. [Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI 96822 (United States); Hayward, Thomas L.; Hartung, Markus [Gemini Observatory, Southern Operations Center, c/o AURA, Casilla 603, La Serena (Chile); Males, Jared R.; Skemer, Andrew; Close, Laird M. [Steward Observatory, University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721 (United States); Chun, Mark [Institute for Astronomy, 640 North Aohoku Place, 209, Hilo, HI 96720-2700 (United States); Clarke, Fraser; Thatte, Niranjan [Department of Astronomy, University of Oxford, DWB, Keble Road, Oxford OX1 3RH (United Kingdom); Shkolnik, Evgenya L. [Lowell Observatory, 1400 West Mars Hill Road Flagstaff, AZ 86001 (United States); Reid, I. Neill [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Boss, Alan [Department of Terrestrial Magnetism, Carnegie Institution of Washington, 5241 Broad Branch Road, NW, Washington, DC 20015 (United States); Lin, Douglas [Department of Astronomy and Astrophysics, University of California, Santa Cruz, CA 95064 (United States); Alencar, Silvia H. P. [Departamento de Fisica-ICEx-Universidade Federal de Minas Gerais, Av. Antonio Carlos 6627, 30270-901 Belo Horizonte, MG (Brazil); De Gouveia Dal Pino, Elisabete; Gregorio-Hetem, Jane [Universidade de Sao Paulo, IAG/USP, Departamento de Astronomia, Rua do Matao 1226, 05508-900 Sao Paulo, SP (Brazil); and others

2013-11-10

We report results of a direct imaging survey for giant planets around 80 members of the β Pic, TW Hya, Tucana-Horologium, AB Dor, and Hercules-Lyra moving groups, observed as part of the Gemini/NICI Planet-Finding Campaign. For this sample, we obtained median contrasts of ΔH = 13.9 mag at 1'' in combined CH{sub 4} narrowband ADI+SDI mode and median contrasts of ΔH = 15.1 mag at 2'' in H-band ADI mode. We found numerous (>70) candidate companions in our survey images. Some of these candidates were rejected as common-proper motion companions using archival data; we reobserved with Near-Infrared Coronagraphic Imager (NICI) all other candidates that lay within 400 AU of the star and were not in dense stellar fields. The vast majority of candidate companions were confirmed as background objects from archival observations and/or dedicated NICI Campaign followup. Four co-moving companions of brown dwarf or stellar mass were discovered in this moving group sample: PZ Tel B (36 ± 6 M{sub Jup}, 16.4 ± 1.0 AU), CD–35 2722B (31 ± 8 M{sub Jup}, 67 ± 4 AU), HD 12894B (0.46 ± 0.08 M{sub ☉}, 15.7 ± 1.0 AU), and BD+07 1919C (0.20 ± 0.03 M{sub ☉}, 12.5 ± 1.4 AU). From a Bayesian analysis of the achieved H band ADI and ASDI contrasts, using power-law models of planet distributions and hot-start evolutionary models, we restrict the frequency of 1-20 M{sub Jup} companions at semi-major axes from 10-150 AU to <18% at a 95.4% confidence level using DUSTY models and to <6% at a 95.4% using COND models. Our results strongly constrain the frequency of planets within semi-major axes of 50 AU as well. We restrict the frequency of 1-20 M{sub Jup} companions at semi-major axes from 10-50 AU to <21% at a 95.4% confidence level using DUSTY models and to <7% at a 95.4% using COND models. This survey is the deepest search to date for giant planets around young moving group stars.

The Breakthrough Listen Initiative and the Future of the Search for Intelligent Life

Science.gov (United States)

Enriquez, J. Emilio; Siemion, Andrew; Croft, Steve; Hellbourg, Greg; Lebofsky, Matt; MacMahon, David; Price, Danny; DeBoer, David; Werthimer, Dan

2017-05-01

Unprecedented recent results in the fields of exoplanets and astrobiology have dramatically increased the interest in the potential existence of intelligent life elsewhere in the galaxy. Additionally, the capabilities of modern Searches for Extraterrestrial Intelligence (SETI) have increased tremendously. Much of this improvement is due to the ongoing development of wide bandwidth radio instruments and the Moore's Law increase in computing power over the previous decades. Together, these instrumentation improvements allow for narrow band signal searches of billions of frequency channels at once.The Breakthrough Listen Initiative (BL) was launched on July 20, 2015 at the Royal Society in London, UK with the goal to conduct the most comprehensive and sensitive search for advanced life in humanity's history. Here we detail important milestones achieved during the first year and a half of the program. We describe the key BL SETI surveys and briefly describe current facilities, including the Green Bank Telescope, the Automated Planet Finder and the Parkes Observatory. We also mention the ongoing and potential collaborations focused on complementary sciences, these include pulse searches of pulsars and FRBs, as well as astrophysically powered radio emission from stars targeted by our program.We conclude with a brief view towards future SETI searches with upcoming next-generation radio facilities such as SKA and ngVLA.

Planet traps and first planets: The critical metallicity for gas giant formation

Energy Technology Data Exchange (ETDEWEB)

Hasegawa, Yasuhiro; Hirashita, Hiroyuki, E-mail: yasu@asiaa.sinica.edu.tw, E-mail: hirashita@asiaa.sinica.edu.tw [Institute of Astronomy and Astrophysics, Academia Sinica (ASIAA), P.O. Box 23-141, Taipei 10617, Taiwan (China)

2014-06-10

The ubiquity of planets poses an interesting question: when are first planets formed in galaxies? We investigate this by adopting a theoretical model where planet traps are combined with the standard core accretion scenario in which the efficiency of forming planetary cores directly relates to the metallicity ([Fe/H]) in disks. Three characteristic exoplanetary populations are examined: hot Jupiters, exo-Jupiters around 1 AU, and low-mass planets in tight orbits, such as super-Earths. We statistically compute planet formation frequencies (PFFs), as well as the orbital radius (〈R{sub rapid}〉) within which gas accretion becomes efficient enough to form Jovian planets, as a function of metallicity (–2 ≤ [Fe/H] ≤–0.6). We show that the total PFFs for these three populations increase steadily with metallicity. This is the direct outcome of the core accretion picture. For the metallicity range considered here, the population of low-mass planets dominates Jovian planets. The Jovian planets contribute to the PFFs above [Fe/H] ≅ –1. We find that the hot Jupiters form more efficiently than the exo-Jupiters at [Fe/H] ≲ –0.7. This arises from the slower growth of planetary cores and their more efficient radial inward transport by the host traps in lower metallicity disks. We show that the critical metallicity for forming Jovian planets is [Fe/H] ≅ –1.2 by comparing 〈R{sub rapid}〉 of hot Jupiters and low-mass planets. The comparison intrinsically links to the different gas accretion efficiency between these two types of planets. Therefore, this study implies that important physical processes in planet formation may be tested by exoplanet observations around metal-poor stars.

Planet traps and first planets: The critical metallicity for gas giant formation

International Nuclear Information System (INIS)

Hasegawa, Yasuhiro; Hirashita, Hiroyuki

2014-01-01

The ubiquity of planets poses an interesting question: when are first planets formed in galaxies? We investigate this by adopting a theoretical model where planet traps are combined with the standard core accretion scenario in which the efficiency of forming planetary cores directly relates to the metallicity ([Fe/H]) in disks. Three characteristic exoplanetary populations are examined: hot Jupiters, exo-Jupiters around 1 AU, and low-mass planets in tight orbits, such as super-Earths. We statistically compute planet formation frequencies (PFFs), as well as the orbital radius (〈R rapid 〉) within which gas accretion becomes efficient enough to form Jovian planets, as a function of metallicity (–2 ≤ [Fe/H] ≤–0.6). We show that the total PFFs for these three populations increase steadily with metallicity. This is the direct outcome of the core accretion picture. For the metallicity range considered here, the population of low-mass planets dominates Jovian planets. The Jovian planets contribute to the PFFs above [Fe/H] ≅ –1. We find that the hot Jupiters form more efficiently than the exo-Jupiters at [Fe/H] ≲ –0.7. This arises from the slower growth of planetary cores and their more efficient radial inward transport by the host traps in lower metallicity disks. We show that the critical metallicity for forming Jovian planets is [Fe/H] ≅ –1.2 by comparing 〈R rapid 〉 of hot Jupiters and low-mass planets. The comparison intrinsically links to the different gas accretion efficiency between these two types of planets. Therefore, this study implies that important physical processes in planet formation may be tested by exoplanet observations around metal-poor stars.

PLANET-PLANET SCATTERING LEADS TO TIGHTLY PACKED PLANETARY SYSTEMS

International Nuclear Information System (INIS)

Raymond, Sean N.; Barnes, Rory; Veras, Dimitri; Armitage, Philip J.; Gorelick, Noel; Greenberg, Richard

2009-01-01

The known extrasolar multiple-planet systems share a surprising dynamical attribute: they cluster just beyond the Hill stability boundary. Here we show that the planet-planet scattering model, which naturally explains the observed exoplanet eccentricity distribution, can reproduce the observed distribution of dynamical configurations. We calculated how each of our scattered systems would appear over an appropriate range of viewing geometries; as Hill stability is weakly dependent on the masses, the mass-inclination degeneracy does not significantly affect our results. We consider a wide range of initial planetary mass distributions and find that some are poor fits to the observed systems. In fact, many of our scattering experiments overproduce systems very close to the stability boundary. The distribution of dynamical configurations of two-planet systems may provide better discrimination between scattering models than the distribution of eccentricity. Our results imply that, at least in their inner regions which are weakly affected by gas or planetesimal disks, planetary systems should be 'packed', with no large gaps between planets.

TESTING IN SITU ASSEMBLY WITH THE KEPLER PLANET CANDIDATE SAMPLE

Energy Technology Data Exchange (ETDEWEB)

Hansen, Brad M. S. [Department of Physics and Astronomy and Institute of Geophysics and Planetary Physics, University of California Los Angeles, Los Angeles, CA 90095 (United States); Murray, Norm, E-mail: hansen@astro.ucla.edu, E-mail: murray@cita.utoronto.ca [Canadian Institute for Theoretical Astrophysics, 60 St. George Street, University of Toronto, Toronto, ON M5S 3H8 (Canada)

2013-09-20

We present a Monte Carlo model for the structure of low-mass (total mass <25 M{sub ⊕}) planetary systems that form by the in situ gravitational assembly of planetary embryos into final planets. Our model includes distributions of mass, eccentricity, inclination, and period spacing that are based on the simulation of a disk of 20 M{sub ⊕}, forming planets around a solar-mass star, and assuming a power-law surface density distribution that drops with distance a as ∝ a {sup –1.5}. The output of the Monte Carlo model is then subjected to the selection effects that mimic the observations of a transiting planet search such as that performed by the Kepler satellite. The resulting comparison of the output to the properties of the observed sample yields an encouraging agreement in terms of the relative frequencies of multiple-planet systems and the distribution of the mutual inclinations when moderate tidal circularization is taken into account. The broad features of the period distribution and radius distribution can also be matched within this framework, although the model underpredicts the distribution of small period ratios. This likely indicates that some dissipation is still required in the formation process. The most striking deviation between the model and observations is in the ratio of single to multiple systems in that there are roughly 50% more single-planet candidates observed than are produced in any model population. This suggests that some systems must suffer additional attrition to reduce the number of planets or increase the range of inclinations.

Planet-planet scattering leads to tightly packed planetary systems

OpenAIRE

Raymond, Sean N.; Barnes, Rory; Veras, Dimitri; Armitage, Philip J.; Gorelick, Noel; Greenberg, Richard

2009-01-01

The known extrasolar multiple-planet systems share a surprising dynamical attribute: they cluster just beyond the Hill stability boundary. Here we show that the planet-planet scattering model, which naturally explains the observed exoplanet eccentricity distribution, can reproduce the observed distribution of dynamical configurations. We calculated how each of our scattered systems would appear over an appropriate range of viewing geometries; as Hill stability is weakly dependent on the masse...

Moon Search Algorithms for NASA's Dawn Mission to Asteroid Vesta

Science.gov (United States)

Memarsadeghi, Nargess; Mcfadden, Lucy A.; Skillman, David R.; McLean, Brian; Mutchler, Max; Carsenty, Uri; Palmer, Eric E.

2012-01-01

A moon or natural satellite is a celestial body that orbits a planetary body such as a planet, dwarf planet, or an asteroid. Scientists seek understanding the origin and evolution of our solar system by studying moons of these bodies. Additionally, searches for satellites of planetary bodies can be important to protect the safety of a spacecraft as it approaches or orbits a planetary body. If a satellite of a celestial body is found, the mass of that body can also be calculated once its orbit is determined. Ensuring the Dawn spacecraft's safety on its mission to the asteroid Vesta primarily motivated the work of Dawn's Satellite Working Group (SWG) in summer of 2011. Dawn mission scientists and engineers utilized various computational tools and techniques for Vesta's satellite search. The objectives of this paper are to 1) introduce the natural satellite search problem, 2) present the computational challenges, approaches, and tools used when addressing this problem, and 3) describe applications of various image processing and computational algorithms for performing satellite searches to the electronic imaging and computer science community. Furthermore, we hope that this communication would enable Dawn mission scientists to improve their satellite search algorithms and tools and be better prepared for performing the same investigation in 2015, when the spacecraft is scheduled to approach and orbit the dwarf planet Ceres.

The Galactic Distribution of Planets via Spitzer Microlensing Parallax

Science.gov (United States)

Gould, Andrew; Yee, Jennifer; Carey, Sean; Shvartzvald, Yossi

2018-05-01

We will measure the Galactic distribution of planets by obtaining 'microlens parallaxes' of about 200 events, including 3 planetary events, from the comparison of microlens lightcurves observed from Spitzer and Earth, which are separated by >1.5 AU in projection. The proposed observations are part of a campaign that we have conducted with Spitzer since 2014. The planets expected to be identified in this campaign when combined with previous work will yield a first statistically significant measurement of the frequency of planets in the Galactic bulge versus the Galactic disk. As we have demonstrated in three previous programs, the difference in these lightcurves yields both the 'microlens parallax' (ratio of the lens-source relative parallax) to the Einstein radius, and the direction of lens-source relative motion. For planetary events, this measurement directly yields the mass and distance of the planet. This proposal is significantly more sensitive to planets than previous work because it takes advantage of the KMTNet observing strategy that covers >85 sq.deg t >0.4/hr cadence, 24/7 from 3 southern observatories and a alert system KMTNet is implementing for 2019. This same observing program also provides a unique probe of dark objects. It will yield an improved measurement of the isolated-brown-dwarf mass function. Thirteen percent of the observations will specifically target binaries, which will probe systems with dark components (brown dwarfs, neutron stars, black holes) that are difficult or impossible to investigate by other methods. The observations and methods from this work are a test bed for WFIRST microlensing.

Searching for Exoplanets around X-Ray Binaries with Accreting White Dwarfs, Neutron Stars, and Black Holes

Science.gov (United States)

Imara, Nia; Di Stefano, Rosanne

2018-05-01

We recommend that the search for exoplanets around binary stars be extended to include X-ray binaries (XRBs) in which the accretor is a white dwarf, neutron star, or black hole. We present a novel idea for detecting planets bound to such mass transfer binaries, proposing that the X-ray light curves of these binaries be inspected for signatures of transiting planets. X-ray transits may be the only way to detect planets around some systems, while providing a complementary approach to optical and/or radio observations in others. Any planets associated with XRBs must be in stable orbits. We consider the range of allowable separations and find that orbital periods can be hours or longer, while transit durations extend upward from about a minute for Earth-radius planets, to hours for Jupiter-radius planets. The search for planets around XRBs could begin at once with existing X-ray observations of these systems. If and when a planet is detected around an X-ray binary, the size and mass of the planet may be readily measured, and it may also be possible to study the transmission and absorption of X-rays through its atmosphere. Finally, a noteworthy application of our proposal is that the same technique could be used to search for signals from extraterrestrial intelligence. If an advanced exocivilization placed a Dyson sphere or similar structure in orbit around the accretor of an XRB in order to capture energy, such an artificial structure might cause detectable transits in the X-ray light curve.

Over 100 Validated and Candidate Planets Orbiting Bright Stars in K2 Campaigns 0-10

Science.gov (United States)

Mayo, Andrew; Vanderburg, Andrew; Latham, David; Bieryla, Allyson; Morton, Timothy

2018-01-01

Since 2014, NASA's K2 mission has observed large portions of the ecliptic plane in search of transiting planets and has detected hundreds of planet candidates. With observations planned until at least early 2018, K2 will continue to identify more planet candidates. We present here over 250 planet candidates observed during Campaigns 0-10 of the K2 mission that are orbiting stars brighter than 13th magnitude and for which we have obtained high-resolution spectra. We analyze these candidates using the VESPA package in order to calculate the false positive probability (FPP), and find that more than half are validated with a FPP less than 0.1%. We show that like the population of planets found during the original Kepler mission, large planets discovered by K2 tend to orbit metal-rich stars. We also show tentative evidence of a gap in the planet radius distribution. We compare our sample to the Kepler candidate sample investigated by Fulton and collaborators and conclude that more planets are required to confirm the gap. This work, in addition to increasing the population of validated K2 planets and providing new targets for follow-up observations, will also serve as a framework for validating candidates from upcoming K2 campaigns and the Transiting Exoplanet Survey Satellite (TESS), expected to launch in 2018.

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

International Nuclear Information System (INIS)

Shoji, D.; Kurita, K.

2014-01-01

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.

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.

High Ph, Ammonia Toxicity, and the Search for Life on the Jovian Planets

Science.gov (United States)

Deal, P. H.; Souza, K. A.; Mack, H. M.

1975-01-01

The effects of pH and ammonia concentration were studied separately, where possible, on a variety of organisms, including some isolated from natural environments of high pH and/or ammonia concentration. Escherichia coli and Bacillus subtilis are both extremely sensitive to ammonia. An aerobic organism (growth up to pH 11.4) from an alkaline spring is more resistant, but exhibits a toxic response to ammonia at a pH much lower than its maximum for growth. The greatest ammonia resistance has been found in an unidentified organism growing at near neutral pH. Even in this case, however, urvival at ammonia concentrations reasonably expected on the Jovian planets is measured in hours. This is two to three orders of magnitude longer than for E. coli. Results support the tentative conclusion that contamination of the Jovian planets with terrestrial organisms that can grow is unlikely. However, the range of toxic response noted, coupled with the observation that terrestrial life has not been exposed to high ammonia concentrations for millions of years, suggests that adaptation to greater ammonia tolerance may be possible.

Kepler Stellar Properties Catalog Update for Q1-Q17 DR25 Transit Search

Science.gov (United States)

Mathur, Savita; Huber, Daniel

2016-01-01

Huber et al. (2014) presented revised stellar properties for 196,468 Kepler targets, which were used for the Q1-Q16 TPSDV planet search (Tenenbaum et al. 2014). The catalog was based on atmospheric properties (i.e., temperature (Teff), surface gravity (log(g)), and metallicity ([FeH])) published in the literature using a variety of methods (e.g., asteroseismology, spectroscopy, exoplanet transits, photometry), which were then homogeneously fitted to a grid of Dartmouth (DSEP) isochrones (Dotter et al. 2008). The catalog was updated in early 2015 for the Q1-Q17 Data Release (DR) 24 transit search (Seader et al. 2015) based on the latest classifications of Kepler targets in the literature at that time. The methodology followed Huber et al. (2014). Here we provide updated stellar properties of 197,096 Kepler targets. Like the previous catalog, this update is based on atmospheric properties that were either published in the literature or provided by the Kepler community follow-up program (CFOP). The input values again come from different methods: asteroseismology, spectroscopy, flicker, and photometry. This catalog update was developed to support the SOC 9.3 TPSDV planet search (Twicken et al. 2016), which is expected to be the final search and data release by the Kepler project.In this document, we describe the method and the inputs that were used to build the catalog. The methodology follows Huber et al. (2014) with a few improvements as described in Section 2.

Follow-Up Photometry of Kelt Transiting Planet Candidates

Science.gov (United States)

Stephens, Denise C.; Joner, Michael D.; Hintz, Eric G.; Martin, Trevor; Spencer, Alex; Kelt Follow-Up Network (FUN) Team

2017-10-01

We have three telescopes at BYU that we use to follow-up possible transiting planet canidates for the KELT team. These telescopes were used to collect data on Kelt-16b and Kelt-9b, which is the hottest known exoplanet. More recently we used the newest of these telescopes, a robotic 8-inch telescope on the roof of our building, to confirm the most recent Kelt planet that will be published soon. This research has been ideal for the teaching and training of undergraduate students in the art of photometric observing and data reduction. In this presentation I will highlight how we are using our membership in the Kelt team to further the educational objective of our undergraduate astronomy program, while contributing meaningful science to the ever growing field of exoplanet discovery. I will also highlight a few of the more interesting Kelt planets and the minimum telescope requirements for detecting these planets. I will then discuss the sensitivities required to follow-up future TESS candidates, which may be of interest to others interested in joining the TESS follow-up teams.

Local beam angle optimization with linear programming and gradient search

International Nuclear Information System (INIS)

Craft, David

2007-01-01

The optimization of beam angles in IMRT planning is still an open problem, with literature focusing on heuristic strategies and exhaustive searches on discrete angle grids. We show how a beam angle set can be locally refined in a continuous manner using gradient-based optimization in the beam angle space. The gradient is derived using linear programming duality theory. Applying this local search to 100 random initial angle sets of a phantom pancreatic case demonstrates the method, and highlights the many-local-minima aspect of the BAO problem. Due to this function structure, we recommend a search strategy of a thorough global search followed by local refinement at promising beam angle sets. Extensions to nonlinear IMRT formulations are discussed. (note)

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...

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.

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

2018-01-01

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.

The hottest planet.

Science.gov (United States)

Harrington, Joseph; Luszcz, Statia; Seager, Sara; Deming, Drake; Richardson, L Jeremy

2007-06-07

Of the over 200 known extrasolar planets, just 14 pass in front of and behind their parent stars as seen from Earth. This fortuitous geometry allows direct determination of many planetary properties. Previous reports of planetary thermal emission give fluxes that are roughly consistent with predictions based on thermal equilibrium with the planets' received radiation, assuming a Bond albedo of approximately 0.3. Here we report direct detection of thermal emission from the smallest known transiting planet, HD 149026b, that indicates a brightness temperature (an expression of flux) of 2,300 +/- 200 K at 8 microm. The planet's predicted temperature for uniform, spherical, blackbody emission and zero albedo (unprecedented for planets) is 1,741 K. As models with non-zero albedo are cooler, this essentially eliminates uniform blackbody models, and may also require an albedo lower than any measured for a planet, very strong 8 microm emission, strong temporal variability, or a heat source other than stellar radiation. On the other hand, an instantaneous re-emission blackbody model, in which each patch of surface area instantly re-emits all received light, matches the data. This planet is known to be enriched in heavy elements, which may give rise to novel atmospheric properties yet to be investigated.

STABILIZING CLOUD FEEDBACK DRAMATICALLY EXPANDS THE HABITABLE ZONE OF TIDALLY LOCKED PLANETS

International Nuclear Information System (INIS)

Yang Jun; Abbot, Dorian S.; Cowan, Nicolas B.

2013-01-01

The habitable zone (HZ) is the circumstellar region where a planet can sustain surface liquid water. Searching for terrestrial planets in the HZ of nearby stars is the stated goal of ongoing and planned extrasolar planet surveys. Previous estimates of the inner edge of the HZ were based on one-dimensional radiative-convective models. The most serious limitation of these models is the inability to predict cloud behavior. Here we use global climate models with sophisticated cloud schemes to show that due to a stabilizing cloud feedback, tidally locked planets can be habitable at twice the stellar flux found by previous studies. This dramatically expands the HZ and roughly doubles the frequency of habitable planets orbiting red dwarf stars. At high stellar flux, strong convection produces thick water clouds near the substellar location that greatly increase the planetary albedo and reduce surface temperatures. Higher insolation produces stronger substellar convection and therefore higher albedo, making this phenomenon a stabilizing climate feedback. Substellar clouds also effectively block outgoing radiation from the surface, reducing or even completely reversing the thermal emission contrast between dayside and nightside. The presence of substellar water clouds and the resulting clement surface conditions will therefore be detectable with the James Webb Space Telescope.

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...

Dance of the Planets

Science.gov (United States)

Riddle, Bob

2005-01-01

As students continue their monthly plotting of the planets along the ecliptic they should start to notice differences between inner and outer planet orbital motions, and their relative position or separation from the Sun. Both inner and outer planets have direct eastward motion, as well as retrograde motion. Inner planets Mercury and Venus,…

Stellar aspects of habitability--characterizing target stars for terrestrial planet-finding missions.

Science.gov (United States)

Kaltenegger, Lisa; Eiroa, Carlos; Ribas, Ignasi; Paresce, Francesco; Leitzinger, Martin; Odert, Petra; Hanslmeier, Arnold; Fridlund, Malcolm; Lammer, Helmut; Beichman, Charles; Danchi, William; Henning, Thomas; Herbst, Tom; Léger, Alain; Liseau, René; Lunine, Jonathan; Penny, Alan; Quirrenbach, Andreas; Röttgering, Huub; Selsis, Frank; Schneider, Jean; Stam, Daphne; Tinetti, Giovanna; White, Glenn J

2010-01-01

We present and discuss the criteria for selecting potential target stars suitable for the search for Earth-like planets, with a special emphasis on the stellar aspects of habitability. Missions that search for terrestrial exoplanets will explore the presence and habitability of Earth-like exoplanets around several hundred nearby stars, mainly F, G, K, and M stars. The evaluation of the list of potential target systems is essential in order to develop mission concepts for a search for terrestrial exoplanets. Using the Darwin All Sky Star Catalogue (DASSC), we discuss the selection criteria, configuration-dependent subcatalogues, and the implication of stellar activity for habitability.

The Search for Life on Mars

Science.gov (United States)

Mumma, Michael J.

2012-01-01

For centuries, the planet Mars has been regarded as a possible abode for life. Serious searches for the signatures of life began in the 19th century, and continue via telescopic investigations and landed missions. While early work focused on phenomenology and bordered on fantasy, modern scientific inquiry has emphasized the search for chemical signatures of life in the soil and rocks at the planet's surface, and the search for biomarker gases in the atmosphere. Living systems produce more than 90% of Earth's atmospheric methane; the balance is of geochemical origin. The discovery of methane on Mars will be described, along with the ongoing extended search for clues to its origins. The possible origins of Mars methane will be discussed in the context of terrestrial analogue sites where geologic and biologic methane production now occurs - ranging from sub-permafrost zones in the arctic to hydrothermal vents in the deep ocean. Terrestrial organisms that could prosper on Mars today will be mentioned. I will briefly touch upon experiments conducted by landed spacecraft, ranging from the Viking Life Science Experiments in 1976 to the impending Mars Science laboratory, and the Trace Gas Orbiter and ExoMars missions now being developed for flight in the coming decade.

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?

PLANET HUNTERS. VIII. CHARACTERIZATION OF 41 LONG-PERIOD EXOPLANET CANDIDATES FROM KEPLER ARCHIVAL DATA

International Nuclear Information System (INIS)

Wang, Ji; Fischer, Debra A.; Picard, Alyssa; Schmitt, Joseph R.; Boyajian, Tabetha S.; Barclay, Thomas; Ma, Bo; Bowler, Brendan P.; Riddle, Reed; Jek, Kian J.; LaCourse, Daryll; Simister, Dean Joseph; Grégoire, Boscher; Babin, Sean P.; Poile, Trevor; Jacobs, Thomas Lee; Baranec, Christoph; Law, Nicholas M.; Lintott, Chris; Schawinski, Kevin

2015-01-01

The census of exoplanets is incomplete for orbital distances larger than 1 AU. Here, we present 41 long-period planet candidates in 38 systems identified by Planet Hunters based on Kepler archival data (Q0–Q17). Among them, 17 exhibit only one transit, 14 have two visible transits, and 10 have more than three visible transits. For planet candidates with only one visible transit, we estimate their orbital periods based on transit duration and host star properties. The majority of the planet candidates in this work (75%) have orbital periods that correspond to distances of 1–3 AU from their host stars. We conduct follow-up imaging and spectroscopic observations to validate and characterize planet host stars. In total, we obtain adaptive optics images for 33 stars to search for possible blending sources. Six stars have stellar companions within 4″. We obtain high-resolution spectra for 6 stars to determine their physical properties. Stellar properties for other stars are obtained from the NASA Exoplanet Archive and the Kepler Stellar Catalog by Huber et al. We validate 7 planet candidates that have planet confidence over 0.997 (3σ level). These validated planets include 3 single-transit planets (KIC-3558849b, KIC-5951458b, and KIC-8540376c), 3 planets with double transits (KIC-8540376b, KIC-9663113b, and KIC-10525077b), and 1 planet with four transits (KIC-5437945b). This work provides assessment regarding the existence of planets at wide separations and the associated false positive rate for transiting observation (17%–33%). More than half of the long-period planets with at least three transits in this paper exhibit transit timing variations up to 41 hr, which suggest additional components that dynamically interact with the transiting planet candidates. The nature of these components can be determined by follow-up radial velocity and transit observations

PLANET HUNTERS. VIII. CHARACTERIZATION OF 41 LONG-PERIOD EXOPLANET CANDIDATES FROM KEPLER ARCHIVAL DATA

Energy Technology Data Exchange (ETDEWEB)

Wang, Ji; Fischer, Debra A.; Picard, Alyssa; Schmitt, Joseph R.; Boyajian, Tabetha S. [Department of Astronomy, Yale University, New Haven, CT 06511 (United States); Barclay, Thomas [NASA Ames Research Center, M/S 244-30, Moffett Field, CA 94035 (United States); Ma, Bo [Department of Astronomy, University of Florida, 211 Bryant Space Science Center, Gainesville, FL 32611-2055 (United States); Bowler, Brendan P.; Riddle, Reed [California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91101 (United States); Jek, Kian J.; LaCourse, Daryll; Simister, Dean Joseph; Grégoire, Boscher; Babin, Sean P.; Poile, Trevor; Jacobs, Thomas Lee; Baranec, Christoph [Institute for Astronomy, University of Hawai‘i at Mānoa, Hilo, HI 96720-2700 (United States); Law, Nicholas M. [Department of Physics and Astronomy, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-3255 (United States); Lintott, Chris [Oxford Astrophysics, Denys Wilkinson Building, Keble Road, Oxford OX1 3RH (United Kingdom); Schawinski, Kevin [Institute for Astronomy, Department of Physics, ETH Zurich, Wolfgang-Pauli-Strasse 27, CH-8093 Zurich (Switzerland); and others

2015-12-20

The census of exoplanets is incomplete for orbital distances larger than 1 AU. Here, we present 41 long-period planet candidates in 38 systems identified by Planet Hunters based on Kepler archival data (Q0–Q17). Among them, 17 exhibit only one transit, 14 have two visible transits, and 10 have more than three visible transits. For planet candidates with only one visible transit, we estimate their orbital periods based on transit duration and host star properties. The majority of the planet candidates in this work (75%) have orbital periods that correspond to distances of 1–3 AU from their host stars. We conduct follow-up imaging and spectroscopic observations to validate and characterize planet host stars. In total, we obtain adaptive optics images for 33 stars to search for possible blending sources. Six stars have stellar companions within 4″. We obtain high-resolution spectra for 6 stars to determine their physical properties. Stellar properties for other stars are obtained from the NASA Exoplanet Archive and the Kepler Stellar Catalog by Huber et al. We validate 7 planet candidates that have planet confidence over 0.997 (3σ level). These validated planets include 3 single-transit planets (KIC-3558849b, KIC-5951458b, and KIC-8540376c), 3 planets with double transits (KIC-8540376b, KIC-9663113b, and KIC-10525077b), and 1 planet with four transits (KIC-5437945b). This work provides assessment regarding the existence of planets at wide separations and the associated false positive rate for transiting observation (17%–33%). More than half of the long-period planets with at least three transits in this paper exhibit transit timing variations up to 41 hr, which suggest additional components that dynamically interact with the transiting planet candidates. The nature of these components can be determined by follow-up radial velocity and transit observations.

The First Brown Dwarf Discovered by the Backyard Worlds: Planet 9 Citizen Science Project

Science.gov (United States)

Kuchner, Marc J.; Faherty, Jacqueline K.; Schneider, Adam C.; Meisner, Aaron M.; Filippazzo, Joseph C.; Gagne, Jonathan; Trouille, Laura; Silverberg, Steven M.; Castro, Rosa; Fletcher, Bob;

BioSearch Marinelife Observer Program for the Northern Mariana Islands

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — BioSearch is a volunteer monitoring program targeting recreational divers and boaters and designed to gather information about occurrences of large or rare...

The Trojan minor planets

Science.gov (United States)

Spratt, Christopher E.

1988-08-01

There are (March, 1988) 3774 minor planets which have received a permanent number. Of these, there are some whose mean distance to the sun is very nearly equal to that of Jupiter, and whose heliocentric longitudes from that planet are about 60°, so that the three bodies concerned (sun, Jupiter, minor planet) make an approximate equilateral triangle. These minor planets, which occur in two distinct groups, one preceding Jupiter and one following, have received the names of the heroes of the Trojan war. This paper concerns the 49 numbered minor planets of this group.

Searching for transits in the WTS with the difference imaging light curves

Science.gov (United States)

Zendejas Dominguez, Jesus

2013-12-01

The search for exo-planets is currently one of the most exiting and active topics in astronomy. Small and rocky planets are particularly the subject of intense research, since if they are suitably located from their host star, they may be warm and potentially habitable worlds. On the other hand, the discovery of giant planets in short-period orbits provides important constraints on models that describe planet formation and orbital migration theories. Several projects are dedicated to discover and characterize planets outside of our solar system. Among them, the Wide-Field Camera Transit Survey (WTS) is a pioneer program aimed to search for extra-solar planets, that stands out for its particular aims and methodology. The WTS has been in operation since August 2007 with observations from the United Kingdom Infrared Telescope, and represents the first survey that searches for transiting planets in the near-infrared wavelengths; hence the WTS is designed to discover planets around M-dwarfs. The survey was originally assigned about 200 nights, observing four fields that were selected seasonally (RA = 03, 07, 17 and 19h) during a year. The images from the survey are processed by a data reduction pipeline, which uses aperture photometry to construct the light curves. For the most complete field (19h-1145 epochs) in the survey, we produce an alternative set of light curves by using the method of difference imaging, which is a photometric technique that has shown important advantages when used in crowded fields. A quantitative comparison between the photometric precision achieved with both methods is carried out in this work. We remove systematic effects using the sysrem algorithm, scale the error bars on the light curves, and perform a comparison of the corrected light curves. The results show that the aperture photometry light curves provide slightly better precision for objects with J detect transits in the WTS light curves, we use a modified version of the box

Inside-out Planet Formation. IV. Pebble Evolution and Planet Formation Timescales

Science.gov (United States)

Hu, Xiao; Tan, Jonathan C.; Zhu, Zhaohuan; Chatterjee, Sourav; Birnstiel, Tilman; Youdin, Andrew N.; Mohanty, Subhanjoy

2018-04-01

Systems with tightly packed inner planets (STIPs) are very common. Chatterjee & Tan proposed Inside-out Planet Formation (IOPF), an in situ formation theory, to explain these planets. IOPF involves sequential planet formation from pebble-rich rings that are fed from the outer disk and trapped at the pressure maximum associated with the dead zone inner boundary (DZIB). Planet masses are set by their ability to open a gap and cause the DZIB to retreat outwards. We present models for the disk density and temperature structures that are relevant to the conditions of IOPF. For a wide range of DZIB conditions, we evaluate the gap-opening masses of planets in these disks that are expected to lead to the truncation of pebble accretion onto the forming planet. We then consider the evolution of dust and pebbles in the disk, estimating that pebbles typically grow to sizes of a few centimeters during their radial drift from several tens of astronomical units to the inner, ≲1 au scale disk. A large fraction of the accretion flux of solids is expected to be in such pebbles. This allows us to estimate the timescales for individual planet formation and the entire planetary system formation in the IOPF scenario. We find that to produce realistic STIPs within reasonable timescales similar to disk lifetimes requires disk accretion rates of ∼10‑9 M ⊙ yr‑1 and relatively low viscosity conditions in the DZIB region, i.e., a Shakura–Sunyaev parameter of α ∼ 10‑4.

Design-considerations For A Ground-based Transit Survey To Find Habitable Planets Around L And T Dwarfs

Science.gov (United States)

Tata, Ramarao; Martin, E.

2011-09-01

Detection of planets in the habitable zone is one of the key drivers of the exoplanet science community. We present a detailed strategy for such detection around L and T dwarfs. We plan to implement the outcome of the analysis as a transit survey to search for planets around known L and T dwarfs. Understanding of the variability of these cool objects will be a worth-while byproduct of such a survey.

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

Science.gov (United States)

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

2018-04-01

The CHaracterizing ExOPlanets Satellite (CHEOPS) mission is planned for launch next year with a major objective being to search for transits of known radial velocity (RV) planets, particularly those orbiting bright stars. Since the RV 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, we address this by predicting a catalogue of homogeneous credible intervals for these three keys terms for 468 planets discovered via RVs. 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 per cent of these will have apparent magnitude of V 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.

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

International Nuclear Information System (INIS)

Ingraham, Patrick; Macintosh, Bruce; Marley, Mark S.; Saumon, Didier; Marois, Christian; Dunn, Jennifer; Erikson, Darren; Barman, Travis; Bauman, Brian; Burrows, Adam; Chilcote, Jeffrey K.; Fitzgerald, Michael P.; De Rosa, Robert J.; Dillon, Daren; Gavel, Donald; Doyon, René; Goodsell, Stephen J.; Hartung, Markus; Hibon, Pascale; Graham, James R.

2014-01-01

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

Inside-out planet formation

International Nuclear Information System (INIS)

Chatterjee, Sourav; Tan, Jonathan C.

2014-01-01

The compact multi-transiting planet systems discovered by Kepler challenge planet formation theories. Formation in situ from disks with radial mass surface density, Σ, profiles similar to the minimum mass solar nebula but boosted in normalization by factors ≳ 10 has been suggested. We propose that a more natural way to create these planets in the inner disk is formation sequentially from the inside-out via creation of successive gravitationally unstable rings fed from a continuous stream of small (∼cm-m size) 'pebbles', drifting inward via gas drag. Pebbles collect at the pressure maximum associated with the transition from a magnetorotational instability (MRI)-inactive ('dead zone') region to an inner MRI-active zone. A pebble ring builds up until it either becomes gravitationally unstable to form an ∼1 M ⊕ planet directly or induces gradual planet formation via core accretion. The planet may undergo Type I migration into the active region, allowing a new pebble ring and planet to form behind it. Alternatively, if migration is inefficient, the planet may continue to accrete from the disk until it becomes massive enough to isolate itself from the accretion flow. A variety of densities may result depending on the relative importance of residual gas accretion as the planet approaches its isolation mass. The process can repeat with a new pebble ring gathering at the new pressure maximum associated with the retreating dead-zone boundary. Our simple analytical model for this scenario of inside-out planet formation yields planetary masses, relative mass scalings with orbital radius, and minimum orbital separations consistent with those seen by Kepler. It provides an explanation of how massive planets can form with tightly packed and well-aligned system architectures, starting from typical protoplanetary disk properties.

ON THE SURVIVABILITY AND METAMORPHISM OF TIDALLY DISRUPTED GIANT PLANETS: THE ROLE OF DENSE CORES

Energy Technology Data Exchange (ETDEWEB)

Liu, Shang-Fei; Lin, Douglas N. C. [Kavli Institute for Astronomy and Astrophysics and Department of Astronomy, Peking University, Beijing 100871 (China); Guillochon, James; Ramirez-Ruiz, Enrico, E-mail: liushangfei@pku.edu.cn [Department of Astronomy and Astrophysics, University of California, Santa Cruz, CA 95064 (United States)

2013-01-01

A large population of planetary candidates in short-period orbits have been found recently through transit searches, mostly with the Kepler mission. Radial velocity surveys have also revealed several Jupiter-mass planets with highly eccentric orbits. Measurements of the Rossiter-McLaughlin effect indicate that the orbital angular momentum vector of some planets is inclined relative to the spin axis of their host stars. This diversity could be induced by post-formation dynamical processes such as planet-planet scattering, the Kozai effect, or secular chaos which brings planets to the vicinity of their host stars. In this work, we propose a novel mechanism to form close-in super-Earths and Neptune-like planets through the tidal disruption of gas giant planets as a consequence of these dynamical processes. We model the core-envelope structure of gas giant planets with composite polytropes which characterize the distinct chemical composition of the core and envelope. Using three-dimensional hydrodynamical simulations of close encounters between Jupiter-like planets and their host stars, we find that the presence of a core with a mass more than 10 times that of the Earth can significantly increase the fraction of envelope which remains bound to it. After the encounter, planets with cores are more likely to be retained by their host stars in contrast with previous studies which suggested that coreless planets are often ejected. As a substantial fraction of their gaseous envelopes is preferentially lost while the dense incompressible cores retain most of their original mass, the resulting metallicity of the surviving planets is increased. Our results suggest that some gas giant planets can be effectively transformed into either super-Earths or Neptune-like planets after multiple close stellar passages. Finally, we analyze the orbits and structure of known planets and Kepler candidates and find that our model is capable of producing some of the shortest-period objects.

A cloaking device for transiting planets

Science.gov (United States)

Kipping, David M.; Teachey, Alex

2016-06-01

The transit method is presently the most successful planet discovery and characterization tool at our disposal. Other advanced civilizations would surely be aware of this technique and appreciate that their home planet's existence and habitability is essentially broadcast to all stars lying along their ecliptic plane. We suggest that advanced civilizations could cloak their presence, or deliberately broadcast it, through controlled laser emission. Such emission could distort the apparent shape of their transit light curves with relatively little energy, due to the collimated beam and relatively infrequent nature of transits. We estimate that humanity could cloak the Earth from Kepler-like broad-band surveys using an optical monochromatic laser array emitting a peak power of ˜30 MW for ˜10 hours per year. A chromatic cloak, effective at all wavelengths, is more challenging requiring a large array of tunable lasers with a total power of ˜250 MW. Alternatively, a civilization could cloak only the atmospheric signatures associated with biological activity on their world, such as oxygen, which is achievable with a peak laser power of just ˜160 kW per transit. Finally, we suggest that the time of transit for optical Search for Extraterrestrial Intelligence (SETI) is analogous to the water-hole in radio SETI, providing a clear window in which observers may expect to communicate. Accordingly, we propose that a civilization may deliberately broadcast their technological capabilities by distorting their transit to an artificial shape, which serves as both a SETI beacon and a medium for data transmission. Such signatures could be readily searched in the archival data of transit surveys.

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

International Nuclear Information System (INIS)

Lykawka, Patryk Sofia; Ito, Takashi

2013-01-01

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 ∼ 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)

The Search for Extraterrestrial Intelligence (SETI)

Science.gov (United States)

Tarter, Jill

The search for evidence of extraterrestrial intelligence is placed in the broader astronomical context of the search for extrasolar planets and biomarkers of primitive life elsewhere in the universe. A decision tree of possible search strategies is presented as well as a brief history of the search for extraterrestrial intelligence (SETI) projects since 1960. The characteristics of 14 SETI projects currently operating on telescopes are discussed and compared using one of many possible figures of merit. Plans for SETI searches in the immediate and more distant future are outlined. Plans for success, the significance of null results, and some opinions on deliberate transmission of signals (as well as listening) are also included. SETI results to date are negative, but in reality, not much searching has yet been done.

The Search for Another Earth

Indian Academy of Sciences (India)

Home; Journals; Resonance – Journal of Science Education; Volume 21; Issue 7. The Search for ... https://www.ias.ac.in/article/fulltext/reso/021/07/0641-0652 ... In the first part of this article, we shall describethe different astronomical methods through whichthe extrasolar planets of various kinds are discovered.In the second ...

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

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.

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

275 Candidates and 149 Validated Planets Orbiting Bright Stars in K2 Campaigns 0–10

DEFF Research Database (Denmark)

Mayo, Andrew W.; Vanderburg, Andrew; Latham, David W.

2018-01-01

Since 2014, NASA’s K2 mission has observed large portions of the ecliptic plane in search of transiting planets and has detected hundreds of planet candidates. With observations planned until at least early 2018, K2 will continue to identify more planet candidates. We present here 275 planet...... candidates observed during Campaigns 0–10 of the K2 mission that are orbiting stars brighter than 13 mag (in Kepler band) and for which we have obtained high-resolution spectra ( R = 44,000). These candidates are analyzed using the vespa package in order to calculate their false-positive probabilities (FPP......). We find that 149 candidates are validated with an FPP lower than 0.1%, 39 of which were previously only candidates and 56 of which were previously undetected. The processes of data reduction, candidate identification, and statistical validation are described, and the demographics of the candidates...

ROTATIONAL SYNCHRONIZATION MAY ENHANCE HABITABILITY FOR CIRCUMBINARY PLANETS: KEPLER BINARY CASE STUDIES

International Nuclear Information System (INIS)

Mason, Paul A.; Zuluaga, Jorge I.; Cuartas-Restrepo, Pablo A.; Clark, Joni M.

2013-01-01

We report a mechanism capable of reducing (or increasing) stellar activity in binary stars, thereby potentially enhancing (or destroying) circumbinary habitability. In single stars, stellar aggression toward planetary atmospheres causes mass-loss, which is especially detrimental for late-type stars, because habitable zones are very close and activity is long lasting. In binaries, tidal rotational breaking reduces magnetic activity, thus reducing harmful levels of X-ray and ultraviolet (XUV) radiation and stellar mass-loss that are able to erode planetary atmospheres. We study this mechanism for all confirmed circumbinary (p-type) planets. We find that main sequence twins provide minimal flux variation and in some cases improved environments if the stars rotationally synchronize within the first Gyr. Solar-like twins, like Kepler 34 and Kepler 35, provide low habitable zone XUV fluxes and stellar wind pressures. These wide, moist, habitable zones may potentially support multiple habitable planets. Solar-type stars with lower mass companions, like Kepler 47, allow for protected planets over a wide range of secondary masses and binary periods. Kepler 38 and related binaries are marginal cases. Kepler 64 and analogs have dramatically reduced stellar aggression due to synchronization of the primary, but are limited by the short lifetime. Kepler 16 appears to be inhospitable to planets due to extreme XUV flux. These results have important implications for estimates of the number of stellar systems containing habitable planets in the Galaxy and allow for the selection of binaries suitable for follow-up searches for habitable planets

ROTATIONAL SYNCHRONIZATION MAY ENHANCE HABITABILITY FOR CIRCUMBINARY PLANETS: KEPLER BINARY CASE STUDIES

Energy Technology Data Exchange (ETDEWEB)

Mason, Paul A. [Department of Physics, University of Texas at El Paso, El Paso, TX 79968 (United States); Zuluaga, Jorge I.; Cuartas-Restrepo, Pablo A. [FACom-Instituto de Fisica-FCEN, Universidad de Antioquia, Calle 70 No. 52-21, Medellin (Colombia); Clark, Joni M. [Department of Mathematics and Physical Sciences, New Mexico State University-DACC, Las Cruces, NM 88003 (United States)

2013-09-10

We report a mechanism capable of reducing (or increasing) stellar activity in binary stars, thereby potentially enhancing (or destroying) circumbinary habitability. In single stars, stellar aggression toward planetary atmospheres causes mass-loss, which is especially detrimental for late-type stars, because habitable zones are very close and activity is long lasting. In binaries, tidal rotational breaking reduces magnetic activity, thus reducing harmful levels of X-ray and ultraviolet (XUV) radiation and stellar mass-loss that are able to erode planetary atmospheres. We study this mechanism for all confirmed circumbinary (p-type) planets. We find that main sequence twins provide minimal flux variation and in some cases improved environments if the stars rotationally synchronize within the first Gyr. Solar-like twins, like Kepler 34 and Kepler 35, provide low habitable zone XUV fluxes and stellar wind pressures. These wide, moist, habitable zones may potentially support multiple habitable planets. Solar-type stars with lower mass companions, like Kepler 47, allow for protected planets over a wide range of secondary masses and binary periods. Kepler 38 and related binaries are marginal cases. Kepler 64 and analogs have dramatically reduced stellar aggression due to synchronization of the primary, but are limited by the short lifetime. Kepler 16 appears to be inhospitable to planets due to extreme XUV flux. These results have important implications for estimates of the number of stellar systems containing habitable planets in the Galaxy and allow for the selection of binaries suitable for follow-up searches for habitable planets.

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.

The Backyard Worlds: Planet 9 Citizen Science Project

Science.gov (United States)

Faherty, Jacqueline K.; Kuchner, Marc; Schneider, Adam; Meisner, Aaron; Gagné, Jonathan; Filippazzo, Joeseph; Trouille, Laura; Backyard Worlds: Planet 9 Collaboration; Jacqueline Faherty

2018-01-01

In February of 2017 our team launched a new citizen science project entitled Backyard Worlds: Planet 9 to scan the cosmos for fast moving stars, brown dwarfs, and even planets. This Zooniverse website, BackyardWorlds.org, invites anyone with a computer or smartphone to flip through WISE images taken over a several year baseline and mark any point source that appears to move. This “blinking technique” is the same that Clyde Tombaugh discovered Pluto with over 80 years ago. In the first few days of our program we recruited over 30,000 volunteers. After 3/4 of a year with the program we have completed 30% of the sky and our participants have identified several hundred candidate movers. These include (1) over 20 candidate Y-type brown dwarfs, (2) a handful of new co-moving systems containing a previously unidentified low mass object and a known nearby star, (3) over 100 previously missed M dwarfs, (4) and more than 200 candidate L and T brown dwarfs, many of which occupy outlier positions on reduced proper motion diagrams. Our first publication credited four citizen scientists as co-authors. The Backyard Worlds: Planet 9 project is both scientifically fruitful and empowering for any mind across the globe that has ever wanted to participate in a discovery-driven astronomy research project.

Histories of terrestrial planets

International Nuclear Information System (INIS)

Benes, K.

1981-01-01

The uneven historical development of terrestrial planets - Mercury, Venus, Earth, Moon and Mars - is probably due to the differences in their size, weight and rotational dynamics in association with the internal planet structure, their distance from the Sun, etc. A systematic study of extraterrestrial planets showed that the time span of internal activity was not the same for all bodies. It is assumed that the initial history of all terrestrial planets was marked with catastrophic events connected with the overall dynamic development of the solar system. In view of the fact that the cores of small terrestrial bodies cooled quicker, their geological development almost stagnated after two or three thousand million years. This is what probably happened to the Mercury and the Moon as well as the Mars. Therefore, traces of previous catastrophic events were preserved on the surface of the planets. On the other hand, the Earth is the most metamorphosed terrestrial planet and compared to the other planets appears to be atypical. Its biosphere is significantly developed as well as the other shell components, its hydrosphere and atmosphere, and its crust is considerably differentiated. (J.P.)

SECULAR BEHAVIOR OF EXOPLANETS: SELF-CONSISTENCY AND COMPARISONS WITH THE PLANET-PLANET SCATTERING HYPOTHESIS

Energy Technology Data Exchange (ETDEWEB)

Timpe, Miles; Barnes, Rory [Astronomy Department, University of Washington, Box 351580, Seattle, WA 98195 (United States); Kopparapu, Ravikumar; Raymond, Sean N. [Virtual Planetary Laboratory, Seattle, WA 98195 (United States); Greenberg, Richard [Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ 85721 (United States); Gorelick, Noel, E-mail: apskier@astro.washington.edu [Google, Inc., 1600 Amphitheater Parkway, Mountain View, CA 94043 (United States)

2013-09-15

If mutual gravitational scattering among exoplanets occurs, then it may produce unique orbital properties. For example, two-planet systems that lie near the boundary between circulation and libration of their periapses could result if planet-planet scattering ejected a former third planet quickly, leaving one planet on an eccentric orbit and the other on a circular orbit. We first improve upon previous work that examined the apsidal behavior of known multiplanet systems by doubling the sample size and including observational uncertainties. This analysis recovers previous results that demonstrated that many systems lay on the apsidal boundary between libration and circulation. We then performed over 12,000 three-dimensional N-body simulations of hypothetical three-body systems that are unstable, but stabilize to two-body systems after an ejection. Using these synthetic two-planet systems, we test the planet-planet scattering hypothesis by comparing their apsidal behavior, over a range of viewing angles, to that of the observed systems and find that they are statistically consistent regardless of the multiplicity of the observed systems. Finally, we combine our results with previous studies to show that, from the sampled cases, the most likely planetary mass function prior to planet-planet scattering follows a power law with index -1.1. We find that this pre-scattering mass function predicts a mutual inclination frequency distribution that follows an exponential function with an index between -0.06 and -0.1.

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...

Discovery of abundant cellulose microfibers encased in 250 Ma Permian halite: a macromolecular target in the search for life on other planets.

Science.gov (United States)

Griffith, Jack D; Willcox, Smaranda; Powers, Dennis W; Nelson, Roger; Baxter, Bonnie K

2008-04-01

In this study, we utilized transmission electron microscopy to examine the contents of fluid inclusions in halite (NaCl) and solid halite crystals collected 650 m below the surface from the Late Permian Salado Formation in southeastern New Mexico (USA). The halite has been isolated from contaminating groundwater since deposition approximately 250 Ma ago. We show that abundant cellulose microfibers are present in the halite and appear remarkably intact. The cellulose is in the form of 5 nm microfibers as well as composite ropes and mats, and was identified by resistance to 0.5 N NaOH treatment and susceptibility to cellulase enzyme treatment. These cellulose microfibers represent the oldest native biological macromolecules to have been directly isolated, examined biochemically, and visualized (without growth or replication) to date. This discovery points to cellulose as an ideal macromolecular target in the search for life on other planets in our Solar System.

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.

Monopole abundance in the Solar System and the intrinsic heat in the Jovian planets

International Nuclear Information System (INIS)

Arafune, J.; Fukugita, M.; Yanagita, S.

1985-01-01

The intrinsic-heat generation has long been known in the Jovian planets. The current view ascribes its origin to the gradual release of primordial heat produced at the birth of these planets. This scenario, however, fails to explain coherently the magnitude of the excess heat in each planet, other than Jupiter, and must invoke some additional sources. We point out the possibility that this heat, or at least a part of it, could be attributed to proton decay which is catalyzed by grand-unified magnetic monopoles (Rubakov effect) captured in the planets. The monopole flux required for this is of order approx.1 x 10 -23 cm -2 sr -1 sec -1 , which is smaller than the limit on the cosmic monopole flux so far obtained. We also show that if the monopole flux is of this order the monopole captured in the Sun gives rise to the neutrino flux ( approx. =35 MeV) which should be detectable in the underground experiment searching for nucleon decays currently in progress

Ground-based search for the brightest transiting planets with the Multi-site All-Sky CAmeRA: MASCARA

Science.gov (United States)

Snellen, Ignas A. G.; Stuik, Remko; Navarro, Ramon; Bettonvil, Felix; Kenworthy, Matthew; de Mooij, Ernst; Otten, Gilles; ter Horst, Rik; le Poole, Rudolf

2012-09-01

The Multi-site All-sky CAmeRA MASCARA is an instrument concept consisting of several stations across the globe, with each station containing a battery of low-cost cameras to monitor the near-entire sky at each location. Once all stations have been installed, MASCARA will be able to provide a nearly 24-hr coverage of the complete dark sky, down to magnitude 8, at sub-minute cadence. Its purpose is to find the brightest transiting exoplanet systems, expected in the V=4-8 magnitude range - currently not probed by space- or ground-based surveys. The bright/nearby transiting planet systems, which MASCARA will discover, will be the key targets for detailed planet atmosphere observations. We present studies on the initial design of a MASCARA station, including the camera housing, domes, and computer equipment, and on the photometric stability of low-cost cameras showing that a precision of 0.3-1% per hour can be readily achieved. We plan to roll out the first MASCARA station before the end of 2013. A 5-station MASCARA can within two years discover up to a dozen of the brightest transiting planet systems in the sky.

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....

Quantum algorithms for the ordered search problem via semidefinite programming

International Nuclear Information System (INIS)

Childs, Andrew M.; Landahl, Andrew J.; Parrilo, Pablo A.

2007-01-01

One of the most basic computational problems is the task of finding a desired item in an ordered list of N items. While the best classical algorithm for this problem uses log 2 N queries to the list, a quantum computer can solve the problem using a constant factor fewer queries. However, the precise value of this constant is unknown. By characterizing a class of quantum query algorithms for the ordered search problem in terms of a semidefinite program, we find quantum algorithms for small instances of the ordered search problem. Extending these algorithms to arbitrarily large instances using recursion, we show that there is an exact quantum ordered search algorithm using 4 log 605 N≅0.433 log 2 N queries, which improves upon the previously best known exact algorithm

The Automation and Exoplanet Orbital Characterization from the Gemini Planet Imager Exoplanet Survey

Science.gov (United States)

Jinfei Wang, Jason; Graham, James; Perrin, Marshall; Pueyo, Laurent; Savransky, Dmitry; Kalas, Paul; arriaga, Pauline; Chilcote, Jeffrey K.; De Rosa, Robert J.; Ruffio, Jean-Baptiste; Sivaramakrishnan, Anand; Gemini Planet Imager Exoplanet Survey Collaboration

2018-01-01

The Gemini Planet Imager (GPI) Exoplanet Survey (GPIES) is a multi-year 600-star survey to discover and characterize young Jovian exoplanets and their planet forming environments. For large surveys like GPIES, it is critical to have a uniform dataset processed with the latest techniques and calibrations. I will describe the GPI Data Cruncher, an automated data processing framework that is able to generate fully reduced data minutes after the data are taken and can also reprocess the entire campaign in a single day on a supercomputer. The Data Cruncher integrates into a larger automated data processing infrastructure which syncs, logs, and displays the data. I will discuss the benefits of the GPIES data infrastructure, including optimizing observing strategies, finding planets, characterizing instrument performance, and constraining giant planet occurrence. I will also discuss my work in characterizing the exoplanets we have imaged in GPIES through monitoring their orbits. Using advanced data processing algorithms and GPI's precise astrometric calibration, I will show that GPI can achieve one milliarcsecond astrometry on the extensively-studied planet Beta Pic b. With GPI, we can confidently rule out a possible transit of Beta Pic b, but have precise timings on a Hill sphere transit, and I will discuss efforts to search for transiting circumplanetary material this year. I will also discuss the orbital monitoring of other exoplanets as part of GPIES.

STELLAR ACTIVITY AND EXCLUSION OF THE OUTER PLANET IN THE HD 99492 SYSTEM

Energy Technology Data Exchange (ETDEWEB)

Kane, Stephen R.; Thirumalachari, Badrinath; Hinkel, Natalie R. [Department of Physics and Astronomy, San Francisco State University, 1600 Holloway Avenue, San Francisco, CA 94132 (United States); Henry, Gregory W. [Center of Excellence in Information Systems, Tennessee State University, 3500 John A. Merritt Blvd., Box 9501, Nashville, TN 37209 (United States); Jensen, Eric L. N. [Dept of Physics and Astronomy, Swarthmore College, Swarthmore, PA 19081 (United States); Boyajian, Tabetha S.; Fischer, Debra A. [Department of Astronomy, Yale University, New Haven, CT 06511 (United States); Howard, Andrew W. [Institute for Astronomy, University of Hawaii, Honolulu, HI 96822 (United States); Isaacson, Howard T. [Astronomy Department, University of California, Berkeley, CA 94720 (United States); Wright, Jason T., E-mail: skane@sfsu.edu [Department of Astronomy and Astrophysics, Pennsylvania State University, 525 Davey Laboratory, University Park, PA 16802 (United States)

2016-03-20

A historical problem for indirect exoplanet detection has been contending with the intrinsic variability of the host star. If the variability is periodic, it can easily mimic various exoplanet signatures, such as radial velocity (RV) variations that originate with the stellar surface rather than the presence of a planet. Here we present an update for the HD 99492 planetary system, using new RV and photometric measurements from the Transit Ephemeris Refinement and Monitoring Survey. Our extended time series and subsequent analyses of the Ca ii H and K emission lines show that the host star has an activity cycle of ∼13 years. The activity cycle correlates with the purported orbital period of the outer planet, the signature of which is thus likely due to the host star activity. We further include a revised Keplerian orbital solution for the remaining planet, along with a new transit ephemeris. Our transit-search observations were inconclusive.

Open System Architecture design for planet surface systems

Science.gov (United States)

Petri, D. A.; Pieniazek, L. A.; Toups, L. D.

1992-01-01

The Open System Architecture is an approach to meeting the needs for flexibility and evolution of the U.S. Space Exploration Initiative program of the manned exploration of the solar system and its permanent settlement. This paper investigates the issues that future activities of the planet exploration program must confront, defines the basic concepts that provide the basis for establishing an Open System Architecture, identifies the appropriate features of such an architecture, and discusses examples of Open System Architectures.

VVV Survey Search for Habitable Planets around M Dwarfs

Science.gov (United States)

Minniti, Dante

2015-08-01

VISTA Variables in the Vía Láctea (VVV) is a public ESO near- infrared (near-IR) variability survey aimed at scanning the Milky Way Bulge and an adjacent section of the mid-plane. The survey covers an area of 562 sqdeg in the Galactic bulge and the southern disk, containing a billion point sources. In this work we discuss the selection of nearby M-type dwarf stars using multicolor cuts. The ZYJHKs photometry allows an accurate estimation of the spectral types of the M-dwarf candidates. Our procedure is applied for fields located far from the Galactic center where the photometric quality is best. The results of this search covering 15 sqdeg allow us to estimate the total number of M-dwarfs that can be photometrically monitored in the VVV database. In addition, we analyze the light curves of the ~10000 best candidate M-dwarf stars searching for extrasolar planetary transits. In this poster we present the light curves of a hundred good transit candidates, and select those that lie in the HZ around their parent stars.

Extreme orbital evolution from hierarchical secular coupling of two giant planets

International Nuclear Information System (INIS)

Teyssandier, Jean; Naoz, Smadar; Lizarraga, Ian; Rasio, Frederic A.

2013-01-01

Observations of exoplanets over the last two decades have revealed a new class of Jupiter-size planets with orbital periods of a few days, the so-called 'hot Jupiters'. Recent measurements using the Rossiter-McLaughlin effect have shown that many (∼50%) of these planets are misaligned; furthermore, some (∼15%) are even retrograde with respect to the stellar spin axis. Motivated by these observations, we explore the possibility of forming retrograde orbits in hierarchical triple configurations consisting of a star-planet inner pair with another giant planet, or brown dwarf, in a much wider orbit. Recently, it was shown that in such a system, the inner planet's orbit can flip back and forth from prograde to retrograde and can also reach extremely high eccentricities. Here we map a significant part of the parameter space of dynamical outcomes for these systems. We derive strong constraints on the orbital configurations for the outer perturber (the tertiary) that could lead to the formation of hot Jupiters with misaligned or retrograde orbits. We focus only on the secular evolution, neglecting other dynamical effects such as mean-motion resonances, as well as all dissipative forces. For example, with an inner Jupiter-like planet initially on a nearly circular orbit at 5 AU, we show that a misaligned hot Jupiter is likely to be formed in the presence of a more massive planetary companion (>2 M J ) within ∼140 AU of the inner system, with mutual inclination >50° and eccentricity above ∼0.25. This is in striking contrast to the test particle approximation, where an almost perpendicular configuration can still cause large-eccentricity excitations, but flips of an inner Jupiter-like planet are much less likely to occur. The constraints we derive can be used to guide future observations and, in particular, searches for more distant companions in systems containing a hot Jupiter.

Did A Planet Survive A Post-Main Sequence Evolutionary Event?

Science.gov (United States)

Sorber, Rebecca; Jang-Condell, Hannah; Zimmerman, Mara

2018-06-01

The GL86 is star system approximately 10 pc away with a main sequence K- type ~ 0.77 M⊙ star (GL 86A) with a white dwarf ~0.49 M⊙ companion (GL86 B). The system has a ~ 18.4 AU semi-major axis, an orbital period of ~353 yrs, and an eccentricity of ~ 0.39. A 4.5 MJ planet orbits the main sequence star with a semi-major axis of 0.113 AU, an orbital period of 15.76 days, in a near circular orbit with an eccentricity of 0.046. If we assume that this planet was formed during the time when the white dwarf was a main sequence star, it would be difficult for the planet to have remained in a stable orbit during the post-main sequence evolution of GL86 B. The post-main sequence evolution with planet survival will be examined by modeling using the program Mercury (Chambers 1999). Using the model, we examine the origins of the planet: whether it formed before or after the post-main sequence evolution of GL86B. The modeling will give us insight into the dynamical evolution of, not only, the binary star system, but also the planet’s life cycle.

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.

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}.

The fate of scattered planets

Energy Technology Data Exchange (ETDEWEB)

Bromley, Benjamin C. [Department of Physics and Astronomy, University of Utah, 115 S 1400 E, Rm 201, Salt Lake City, UT 84112 (United States); Kenyon, Scott J., E-mail: bromley@physics.utah.edu, E-mail: skenyon@cfa.harvard.edu [Smithsonian Astrophysical Observatory, 60 Garden Street, Cambridge, MA 02138 (United States)

2014-12-01

As gas giant planets evolve, they may scatter other planets far from their original orbits to produce hot Jupiters or rogue planets that are not gravitationally bound to any star. Here, we consider planets cast out to large orbital distances on eccentric, bound orbits through a gaseous disk. With simple numerical models, we show that super-Earths can interact with the gas through dynamical friction to settle in the remote outer regions of a planetary system. Outcomes depend on planet mass, the initial scattered orbit, and the evolution of the time-dependent disk. Efficient orbital damping by dynamical friction requires planets at least as massive as the Earth. More massive, longer-lived disks damp eccentricities more efficiently than less massive, short-lived ones. Transition disks with an expanding inner cavity can circularize orbits at larger distances than disks that experience a global (homologous) decay in surface density. Thus, orbits of remote planets may reveal the evolutionary history of their primordial gas disks. A remote planet with an orbital distance ∼100 AU from the Sun is plausible and might explain correlations in the orbital parameters of several distant trans-Neptunian objects.

2013 - Life is a Cosmic Phenomenon : The "Search for Water" evolves into the "Search for Life"

Science.gov (United States)

Smith, William E.

2013-03-01

We propose that the 2013 data from the Kepler Mission (giving a current estimate of the number of earth-like planets in the habitable zone of sun-like stars as 144 billion), has caused a consciousness change in human belief in the probability of life off earth. This seems to have affected NASA's public statements which are now leaning to the more visionary mission goal of the "Search for Life" rather than the 1975-2012 focus of the "Search for Water". We propose that the first confirmed earth-like planet, expected to be announced later this year, be called "BORUCKI" in honour of the visionary USA scientist Bill Borucki, the father of the Kepler Mission. We explore the 2013 status of the Hoyle-Wickramasinghe Model of Panspermia, its hypothesis, propositions, experiments and evidence. We use the Karl Popper model for scientific hypotheses (1). Finally we explore Sir Fred Hoyle's vision of a planetary microbe defense system we call the Hoyle Shield. We explore the subsystem components of the shield and assess some options for these components using break-though technologies already available.

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

Long Term Evolution of Planetary Systems with a Terrestrial Planet and a Giant Planet

Science.gov (United States)

Georgakarakos, Nikolaos; Dobbs-Dixon, Ian; Way, Michael J.

2016-01-01

We study the long term orbital evolution of a terrestrial planet under the gravitational perturbations of a giant planet. In particular, we are interested in situations where the two planets are in the same plane and are relatively close. We examine both possible configurations: the giant planet orbit being either outside or inside the orbit of the smaller planet. The perturbing potential is expanded to high orders and an analytical solution of the terrestrial planetary orbit is derived. The analytical estimates are then compared against results from the numerical integration of the full equations of motion and we find that the analytical solution works reasonably well. An interesting finding is that the new analytical estimates improve greatly the predictions for the timescales of the orbital evolution of the terrestrial planet compared to an octupole order expansion. Finally, we briefly discuss possible applications of the analytical estimates in astrophysical problems.

The Fate of Unstable Circumbinary Planets

Science.gov (United States)

Kohler, Susanna

2016-03-01

What happens to Tattooine-like planets that are instead in unstable orbits around their binary star system? A new study examines whether such planets will crash into a host star, get ejected from the system, or become captured into orbit around one of their hosts.Orbit Around a DuoAt this point we have unambiguously detected multiple circumbinary planets, raising questions about these planets formation and evolution. Current models suggest that it is unlikely that circumbinary planets would be able to form in the perturbed environment close their host stars. Instead, its thought that the planets formed at a distance and then migrated inwards.One danger such planets face when migrating is encountering ranges of radii where their orbits become unstable. Two scientists at the University of Chicago, Adam Sutherland and Daniel Fabrycky, have studied what happens when circumbinary planets migrate into such a region and develop unstable orbits.Producing Rogue PlanetsTime for planets to either be ejected or collide with one of the two stars, as a function of the planets starting distance (in AU) from the binary barycenter. Colors represent different planetary eccentricities. [Sutherland Fabrycky 2016]Sutherland and Fabrycky used N-body simulations to determine the fates of planets orbiting around a star system consisting of two stars a primary like our Sun and a secondary roughly a tenth of its size that are separated by 1 AU.The authors find that the most common fate for a circumbinary planet with an unstable orbit is ejection from the system; over 80% of unstable planets were ejected. This has interesting implications: if the formation of circumbinary planets is common, this mechanism could be filling the Milky Way with a population of free-floating, rogue planets that no longer are associated with their host star.The next most common outcome for unstable planets is collision with one of their host stars (most often the secondary), resulting inaccretion of the planet

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.

Fundmental Parameters of Low-Mass Stars, Brown Dwarfs, and Planets

Science.gov (United States)

Montet, Benjamin; Johnson, John A.; Bowler, Brendan; Shkolnik, Evgenya

2016-01-01

Despite advances in evolutionary models of low-mass stars and brown dwarfs, these models remain poorly constrained by observations. In order to test these predictions directly, masses of individual stars must be measured and combined with broadband photometry and medium-resolution spectroscopy to probe stellar atmospheres. I will present results from an astrometric and spectroscopic survey of low-mass pre-main sequence binary stars to measure individual dynamical masses and compare to model predictions. This is the first systematic test of a large number of stellar systems of intermediate age between young star-forming regions and old field stars. Stars in our sample are members of the Tuc-Hor, AB Doradus, and beta Pictoris moving groups, the last of which includes GJ 3305 AB, the wide binary companion to the imaged exoplanet host 51 Eri. I will also present results of Spitzer observations of secondary eclipses of LHS 6343 C, a T dwarf transiting one member of an M+M binary in the Kepler field. By combining these data with Kepler photometry and radial velocity observations, we can measure the luminosity, mass, and radius of the brown dwarf. This is the first non-inflated brown dwarf for which all three of these parameters have been measured, providing the first benchmark to test model predictions of the masses and radii of field T dwarfs. I will discuss these results in the context of K2 and TESS, which will find additional benchmark transiting brown dwarfs over the course of their missions, including a description of the first planet catalog developed from K2 data and a program to search for transiting planets around mid-M dwarfs.

Stellar variability and its implications for photometric planet detection with Kepler

Science.gov (United States)

Batalha, N. M.; Jenkins, J.; Basri, G. S.; Borucki, W. J.; Koch, D. G.

2002-01-01

Kepler is one of three candidates for the next NASA Discovery Mission and will survey the extended solar neighborhood to detect and characterize hundreds of terrestrial (and larger) planets in or near the habitable zone. Its strength lies in its ability to detect large numbers of Earth-sized planets - planets which produced a 10-4 change in relative stellar brightness during a transit across the disk of a sun-like parent star. Such a detection requires high instrumental relative precision and is facilitated by observing stars which are photometrically quiet on hourly timescales. Probing stellar variability across the HR diagram, one finds that many of the photometrically quietest stars are the F and G dwarfs. The Hipparcos photometric database shows the lowest photometric variances among stars of this spectral class. Our own Sun is a prime example with RMS variations over a few rotational cycles of typically (3 - 4)×10-4 (computed from VIRGO/DIARAD data taken Jan-Mar 2001). And variability on the hourly time scales crucial for planet detection is significantly smaller: just (2 - 5)×10-5. This bodes well for planet detection programs such as Kepler and Eddington. With significant numbers of photometrically quiet solar-type stars, Earth-sized planets should be readily identified provided they are abundant in the solar neighborhood. In support of the Kepler science objectives, we have initiated a study of stellar variability and its implications for planet detection. Herein, we summarize existing observational and theoretrical work with the objective of determining the percentage of stars in the Kepler field of view expected to be photometrically stable at a level which allows for Earth-sized planet detection.

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.

Migration of accreting giant planets

Science.gov (United States)

Crida, A.; Bitsch, B.; Raibaldi, A.

2016-12-01

We present the results of 2D hydro simulations of giant planets in proto-planetary discs, which accrete gas at a more or less high rate. First, starting from a solid core of 20 Earth masses, we show that as soon as the runaway accretion of gas turns on, the planet is saved from type I migration : the gap opening mass is reached before the planet is lost into its host star. Furthermore, gas accretion helps opening the gap in low mass discs. Consequently, if the accretion rate is limited to the disc supply, then the planet is already inside a gap and in type II migration. We further show that the type II migration of a Jupiter mass planet actually depends on its accretion rate. Only when the accretion is high do we retrieve the classical picture where no gas crosses the gap and the planet follows the disc spreading. These results impact our understanding of planet migration and planet population synthesis models. The e-poster presenting these results in French can be found here: L'e-poster présentant ces résultats en français est disponible à cette adresse: http://sf2a.eu/semaine-sf2a/2016/posterpdfs/156_179_49.pdf.

International Deep Planet Survey, 317 stars to determine the wide-separated planet frequency

Science.gov (United States)

Galicher, R.; Marois, C.; Macintosh, B.; Zuckerman, B.; Song, I.; Barman, T.; Patience, J.

2013-09-01

Since 2000, more than 300 nearby young stars were observed for the International Deep Planet Survey with adaptive optics systems at Gemini (NIRI/NICI), Keck (Nirc2), and VLT (Naco). Massive young AF stars were included in our sample whereas they have generally been neglected in first generation surveys because the contrast and target distances are less favorable to image substellar companions. The most significant discovery of the campaign is the now well-known HR 8799 multi-planet system. This remarkable finding allows, for the first time, an estimate of the Jovians planet population at large separations (further than a few AUs) instead of deriving upper limits. During my presentation, I will present the survey showing images of multiple stars and planets. I will then propose a statistic study of the observed stars deriving constraints on the Jupiter-like planet frequency at large separations.

BD+15 2940 AND HD 233604: TWO GIANTS WITH PLANETS CLOSE TO THE ENGULFMENT ZONE

International Nuclear Information System (INIS)

Nowak, G.; Niedzielski, A.; Adamów, M.; Maciejewski, G.; Wolszczan, A.

2013-01-01

We report the discovery of planetary-mass companions to two red giants by the ongoing Penn State-Toruń Planet Search (PTPS) conducted with the 9.2 m Hobby-Eberly Telescope. The 1.1 M ☉ K0-giant, BD+15 2940, has a 1.1 M J minimum mass companion orbiting the star at a 137.5 day period in a 0.54 AU orbit what makes it the closest—in planet around a giant and possible subject of engulfment as the consequence of stellar evolution. HD 233604, a 1.5 M ☉ K5-giant, is orbited by a 6.6 M J minimum mass planet which has a period of 192 days and a semi-major axis of only 0.75 AU making it one of the least distant planets to a giant star. The chemical composition analysis of HD 233604 reveals a relatively high 7 Li abundance which may be a sign of its early evolutionary stage or recent engulfment of another planet in the system. We also present independent detections of planetary-mass companions to HD 209458 and HD 88133, and stellar activity-induced radial velocity variations in HD 166435, as part of the discussion of the observing and data analysis methods used in the PTPS project.

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.

A search for radio emission from exoplanets around evolved stars

Science.gov (United States)

O'Gorman, E.; Coughlan, C. P.; Vlemmings, W.; Varenius, E.; Sirothia, S.; Ray, T. P.; Olofsson, H.

2018-04-01

The majority of searches for radio emission from exoplanets have to date focused on short period planets, i.e., the so-called hot Jupiter type planets. However, these planets are likely to be tidally locked to their host stars and may not generate sufficiently strong magnetic fields to emit electron cyclotron maser emission at the low frequencies used in observations (typically ≥150 MHz). In comparison, the large mass-loss rates of evolved stars could enable exoplanets at larger orbital distances to emit detectable radio emission. Here, we first show that the large ionized mass-loss rates of certain evolved stars relative to the solar value could make them detectable with the LOw Frequency ARray (LOFAR) at 150 MHz (λ = 2 m), provided they have surface magnetic field strengths >50 G. We then report radio observations of three long period (>1 au) planets that orbit the evolved stars β Gem, ι Dra, and β UMi using LOFAR at 150 MHz. We do not detect radio emission from any system but place tight 3σ upper limits of 0.98, 0.87, and 0.57 mJy on the flux density at 150 MHz for β Gem, ι Dra, and β UMi, respectively. Despite our non-detections these stringent upper limits highlight the potential of LOFAR as a tool to search for exoplanetary radio emission at meter wavelengths.

Nearby Red Dwarfs are Sexy for Planets and Life

Science.gov (United States)

Henry, T. J.; Jao, W.-C.; Subasavage, J. P.; RECONS Team

2005-12-01

The RECONS group continues to discover many nearby red dwarfs in the southern sky through a combination of proper motion surveys, literature review, and ultimately, our parallax program CTIOPI. Already, we have measured the first accurate parallaxes for 11 of the nearest 100 stellar systems, including four within 5 parsecs of the Sun. These nearby red dwarfs are prime candidates for NASA's Space Interferometry Mission (SIM) because the astrometric perturbations are largest for planets orbiting stars of low mass that are nearby. In addition, new multiple red dwarf systems can be targeted for mass determinations, thereby providing points on a comprehensive mass-luminosity relation for the most populous members of the Galaxy. Recent atmospheric modeling of planets orbiting red dwarfs indicates that even if the planets are tidally locked, heat distribution is highly effective in keeping the worlds balmy over the entire surface. Red dwarfs are therefore "back on the table" as viable hosts of life-bearing planets. Given their ubiquity, red dwarfs are being seriously considered as prime SETI targets, and will allow us to answer not only the question "Are We Alone?" but "Just How Alone Are We?" This work has been supported by the National Science Foundation, NASA's Space Interferometry Mission, and Georgia State University.

Find - a computer program for peak search in gamma-ray spectra measured with Ge (Li) detectors

International Nuclear Information System (INIS)

Venturini, L.

1988-01-01

The program FIND is a FORTRAN IV computer code for peak search in spectra measured with Ge(Li) detectors. The program gives the position and estimates energy and relative significance for every peak found in the spectrum. The search in done by calculating a negative smoothed second difference of the experimental spectrum, as suggested by Phillips and Marlow (1). (author) [pt

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...

Rocky Planet Formation: Quick and Neat

Science.gov (United States)

Kenyon, Scott J.; Najita, Joan R.; Bromley, Benjamin C.

2016-11-01

We reconsider the commonly held assumption that warm debris disks are tracers of terrestrial planet formation. The high occurrence rate inferred for Earth-mass planets around mature solar-type stars based on exoplanet surveys (˜20%) stands in stark contrast to the low incidence rate (≤2%-3%) of warm dusty debris around solar-type stars during the expected epoch of terrestrial planet assembly (˜10 Myr). If Earth-mass planets at au distances are a common outcome of the planet formation process, this discrepancy suggests that rocky planet formation occurs more quickly and/or is much neater than traditionally believed, leaving behind little in the way of a dust signature. Alternatively, the incidence rate of terrestrial planets has been overestimated, or some previously unrecognized physical mechanism removes warm dust efficiently from the terrestrial planet region. A promising removal mechanism is gas drag in a residual gaseous disk with a surface density ≳10-5 of the minimum-mass solar nebula.

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

International Nuclear Information System (INIS)

Quintana, Elisa V.; Lissauer, Jack J.

2014-01-01

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 ⊕ to 1 M 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.

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.

KEPLER PLANETS: A TALE OF EVAPORATION

International Nuclear Information System (INIS)

Owen, James E.; Wu, Yanqin

2013-01-01

Inspired by the Kepler mission's planet discoveries, we consider the thermal contraction of planets close to their parent star, under the influence of evaporation. The mass-loss rates are based on hydrodynamic models of evaporation that include both X-ray and EUV irradiation. We find that only low mass planets with hydrogen envelopes are significantly affected by evaporation, with evaporation being able to remove massive hydrogen envelopes inward of ∼0.1 AU for Neptune-mass objects, while evaporation is negligible for Jupiter-mass objects. Moreover, most of the evaporation occurs in the first 100 Myr of stars' lives when they are more chromospherically active. We construct a theoretical population of planets with varying core masses, envelope masses, orbital separations, and stellar spectral types, and compare this population with the sizes and densities measured for low-mass planets, both in the Kepler mission and from radial velocity surveys. This exercise leads us to conclude that evaporation is the driving force of evolution for close-in Kepler planets. In fact, some 50% of the Kepler planet candidates may have been significantly eroded. Evaporation explains two striking correlations observed in these objects: a lack of large radius/low density planets close to the stars and a possible bimodal distribution in planet sizes with a deficit of planets around 2 R ⊕ . Planets that have experienced high X-ray exposures are generally smaller than this size, and those with lower X-ray exposures are typically larger. A bimodal planet size distribution is naturally predicted by the evaporation model, where, depending on their X-ray exposure, close-in planets can either hold on to hydrogen envelopes ∼0.5%-1% in mass or be stripped entirely. To quantitatively reproduce the observed features, we argue that not only do low-mass Kepler planets need to be made of rocky cores surrounded with hydrogen envelopes, but few of them should have initial masses above 20 M ⊕ and

KEPLER PLANETS: A TALE OF EVAPORATION

Energy Technology Data Exchange (ETDEWEB)

Owen, James E. [Canadian Institute for Theoretical Astrophysics, 60 St. George Street, Toronto, ON M5S 3H8 (Canada); Wu, Yanqin, E-mail: jowen@cita.utoronto.ca, E-mail: wu@astro.utoronto.ca [Department of Astronomy and Astrophysics, University of Toronto, Toronto, ON M5S 3H4 (Canada)

2013-10-01

Inspired by the Kepler mission's planet discoveries, we consider the thermal contraction of planets close to their parent star, under the influence of evaporation. The mass-loss rates are based on hydrodynamic models of evaporation that include both X-ray and EUV irradiation. We find that only low mass planets with hydrogen envelopes are significantly affected by evaporation, with evaporation being able to remove massive hydrogen envelopes inward of ∼0.1 AU for Neptune-mass objects, while evaporation is negligible for Jupiter-mass objects. Moreover, most of the evaporation occurs in the first 100 Myr of stars' lives when they are more chromospherically active. We construct a theoretical population of planets with varying core masses, envelope masses, orbital separations, and stellar spectral types, and compare this population with the sizes and densities measured for low-mass planets, both in the Kepler mission and from radial velocity surveys. This exercise leads us to conclude that evaporation is the driving force of evolution for close-in Kepler planets. In fact, some 50% of the Kepler planet candidates may have been significantly eroded. Evaporation explains two striking correlations observed in these objects: a lack of large radius/low density planets close to the stars and a possible bimodal distribution in planet sizes with a deficit of planets around 2 R{sub ⊕}. Planets that have experienced high X-ray exposures are generally smaller than this size, and those with lower X-ray exposures are typically larger. A bimodal planet size distribution is naturally predicted by the evaporation model, where, depending on their X-ray exposure, close-in planets can either hold on to hydrogen envelopes ∼0.5%-1% in mass or be stripped entirely. To quantitatively reproduce the observed features, we argue that not only do low-mass Kepler planets need to be made of rocky cores surrounded with hydrogen envelopes, but few of them should have initial masses above

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.

SearchResultFinder: federated search made easy

NARCIS (Netherlands)

Trieschnigg, Rudolf Berend; Tjin-Kam-Jet, Kien; Hiemstra, Djoerd

Building a federated search engine based on a large number existing web search engines is a challenge: implementing the programming interface (API) for each search engine is an exacting and time-consuming job. In this demonstration we present SearchResultFinder, a browser plugin which speeds up

Planet formation in Binaries

OpenAIRE

Thebault, Ph.; Haghighipour, N.

2014-01-01

Spurred by the discovery of numerous exoplanets in multiple systems, binaries have become in recent years one of the main topics in planet formation research. Numerous studies have investigated to what extent the presence of a stellar companion can affect the planet formation process. Such studies have implications that can reach beyond the sole context of binaries, as they allow to test certain aspects of the planet formation scenario by submitting them to extreme environments. We review her...

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.

The CARMENES Search for Exoplanets around M Dwarfs: A Low-mass Planet in the Temperate Zone of the Nearby K2-18

Science.gov (United States)

Sarkis, Paula; Henning, Thomas; Kürster, Martin; Trifonov, Trifon; Zechmeister, Mathias; Tal-Or, Lev; Anglada-Escudé, Guillem; Hatzes, Artie P.; Lafarga, Marina; Dreizler, Stefan; Ribas, Ignasi; Caballero, José A.; Reiners, Ansgar; Mallonn, Matthias; Morales, Juan C.; Kaminski, Adrian; Aceituno, Jesús; Amado, Pedro J.; Béjar, Victor J. S.; Hagen, Hans-Jürgen; Jeffers, Sandra; Quirrenbach, Andreas; Launhardt, Ralf; Marvin, Christopher; Montes, David

2018-06-01

K2-18 is a nearby M2.5 dwarf, located at 34 pc and hosting a transiting planet that was first discovered by the K2 mission and later confirmed with Spitzer Space Telescope observations. With a radius of ∼2 R ⊕ and an orbital period of ∼33 days, the planet lies in the temperate zone of its host star and receives stellar irradiation similar to that of Earth. Here we perform radial velocity follow-up observations with the visual channel of CARMENES with the goal of determining the mass and density of the planet. We measure a planetary semi-amplitude of K b ∼ 3.5 {{m}} {{{s}}}-1 and a mass of M b ∼ 9 M ⊕, yielding a bulk density around {ρ }b∼ 4 {{g}} {cm}}-3. This indicates a low-mass planet with a composition consistent with a solid core and a volatile-rich envelope. A signal at 9 days was recently reported using radial velocity measurements taken with the HARPS spectrograph. This was interpreted as being due to a second planet. We see a weaker, time- and wavelength-dependent signal in the CARMENES data set and thus favor stellar activity for its origin. K2-18 b joins the growing group of low-mass planets detected in the temperate zone of M dwarfs. The brightness of the host star in the near-infrared makes the system a good target for detailed atmospheric studies with the James Webb Space Telescope.

The geologic evolution of the planet Mars

International Nuclear Information System (INIS)

Masson, P.

1982-01-01

A brief summary of our knowledge on the Martian geology is presented here based on the results published by the members of Mariner 9 and Viking Orbiter Imaging Teams, the NASA Planetary Geology Principal Investigators and the scientists involved in the Mars Data Analysis Program. A special emphasis is given to the geologic evolution (volcanism and tectonism) related to our knowledge on the internal structure of the planet

PLANETS AROUND LOW-MASS STARS (PALMS). IV. THE OUTER ARCHITECTURE OF M DWARF PLANETARY SYSTEMS

Energy Technology Data Exchange (ETDEWEB)

Bowler, Brendan P. [California Institute of Technology, Division of Geological and Planetary Sciences, 1200 East California Boulevard, Pasadena, CA 91101 (United States); Liu, Michael C. [Institute for Astronomy, University of Hawai' i, 2680 Woodlawn Drive, Honolulu, HI 96822 (United States); Shkolnik, Evgenya L. [Lowell Observatory, 1400 West Mars Hill Road, Flagstaff, AZ 86001 (United States); Tamura, Motohide, E-mail: bpbowler@caltech.edu [National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan)

2015-01-01

We present results from a high-contrast adaptive optics imaging search for giant planets and brown dwarfs (≳1 M {sub Jup}) around 122 newly identified nearby (≲40 pc) young M dwarfs. Half of our targets are younger than 135 Myr and 90% are younger than the Hyades (620 Myr). After removing 44 close stellar binaries (implying a stellar companion fraction of >35.4% ± 4.3% within 100 AU), 27 of which are new or spatially resolved for the first time, our remaining sample of 78 single M dwarfs makes this the largest imaging search for planets around young low-mass stars (0.1-0.6 M {sub ☉}) to date. Our H- and K-band coronagraphic observations with Keck/NIRC2 and Subaru/HiCIAO achieve typical contrasts of 12-14 mag and 9-13 mag at 1'', respectively, which correspond to limiting planet masses of 0.5-10 M {sub Jup} at 5-33 AU for 85% of our sample. We discovered four young brown dwarf companions: 1RXS J235133.3+312720 B (32 ± 6 M {sub Jup}; L0{sub −1}{sup +2}; 120 ± 20 AU), GJ 3629 B (64{sub −23}{sup +30} M {sub Jup}; M7.5 ± 0.5; 6.5 ± 0.5 AU), 1RXS J034231.8+121622 B (35 ± 8 M {sub Jup}; L0 ± 1; 19.8 ± 0.9 AU), and 2MASS J15594729+4403595 B (43 ± 9 M {sub Jup}; M8.0 ± 0.5; 190 ± 20 AU). Over 150 candidate planets were identified; we obtained follow-up imaging for 56% of these but all are consistent with background stars. Our null detection of planets enables strong statistical constraints on the occurrence rate of long-period giant planets around single M dwarfs. We infer an upper limit (at the 95% confidence level) of 10.3% and 16.0% for 1-13 M {sub Jup} planets between 10-100 AU for hot-start and cold-start (Fortney) evolutionary models, respectively. Fewer than 6.0% (9.9%) of M dwarfs harbor massive gas giants in the 5-13 M {sub Jup} range like those orbiting HR 8799 and β Pictoris between 10-100 AU for a hot-start (cold-start) formation scenario. The frequency of brown dwarf (13-75 M {sub Jup}) companions

THE NASA-UC ETA-EARTH PROGRAM. II. A PLANET ORBITING HD 156668 WITH A MINIMUM MASS OF FOUR EARTH MASSES

International Nuclear Information System (INIS)

Howard, Andrew W.; Marcy, Geoffrey W.; Isaacson, Howard; Johnson, John Asher; Fischer, Debra A.; Wright, Jason T.; Henry, Gregory W.; Valenti, Jeff A.; Anderson, Jay; Piskunov, Nikolai E.

2011-01-01

We report the discovery of HD 156668 b, an extrasolar planet with a minimum mass of M P sin i = 4.15 M + . This planet was discovered through Keplerian modeling of precise radial velocities from Keck-HIRES and is the second super-Earth to emerge from the NASA-UC Eta-Earth Survey. The best-fit orbit is consistent with circular and has a period of P = 4.6455 days. The Doppler semi-amplitude of this planet, K = 1.89 m s -1 , is among the lowest ever detected, on par with the detection of GJ 581 e using HARPS. A longer period (P ∼ 2.3 years), low-amplitude signal of unknown origin was also detected in the radial velocities and was filtered out of the data while fitting the short-period planet. Additional data are required to determine if the long-period signal is due to a second planet, stellar activity, or another source. Photometric observations using the Automated Photometric Telescopes at Fairborn Observatory show that HD 156668 (an old, quiet K3 dwarf) is photometrically constant over the radial velocity period to 0.1 mmag, supporting the existence of the planet. No transits were detected down to a photometric limit of ∼3 mmag, ruling out transiting planets dominated by extremely bloated atmospheres, but not precluding a transiting solid/liquid planet with a modest atmosphere.

The economic effect of Planet Health on preventing bulimia nervosa.

Science.gov (United States)

Wang, Li Yan; Nichols, Lauren P; Austin, S Bryn

2011-08-01

To assess the economic effect of the school-based obesity prevention program Planet Health on preventing disordered weight control behaviors and to determine the cost-effectiveness of the intervention in terms of its combined effect on prevention of obesity and disordered weight control behaviors. On the basis of the intervention's short-term effect on disordered weight control behaviors prevention, we projected the number of girls who were prevented from developing bulimia nervosa by age 17 years. We further estimated medical costs saved and quality-adjusted life years gained by the intervention over 10 years. As a final step, we compared the intervention costs with the combined intervention benefits from both obesity prevention (reported previously) and prevention of disordered weight control behaviors to determine the overall cost-effectiveness of the intervention. Middle schools. A sample of 254 intervention girls aged 10 to 14 years. The Planet Health program was implemented during the school years from 1995 to 1997 and was designed to promote healthful nutrition and physical activity among youth. Intervention costs, medical costs saved, quality-adjusted life years gained, and cost-effectiveness ratio. An estimated 1 case of bulimia nervosa would have been prevented. As a result, an estimated $33 999 in medical costs and 0.7 quality-adjusted life years would be saved. At an intervention cost of $46 803, the combined prevention of obesity and disordered weight control behaviors would yield a net savings of $14 238 and a gain of 4.8 quality-adjusted life years. Primary prevention programs, such as Planet Health, warrant careful consideration by policy makers and program planners. The findings of this study provide additional argument for integrated prevention of obesity and eating disorders.

Trapping planets in an evolving protoplanetary disk: preferred time, locations and planet mass

OpenAIRE

Baillié, Kévin; Charnoz, Sébastien; Pantin, Éric

2016-01-01

Planet traps are necessary to prevent forming planets from falling onto their host star by type I migration. Surface mass density and temperature gradient irregularities favor the apparition of traps and deserts. Such features are found at the dust sublimation lines and heat transition barriers. We study how planets may remain trapped or escape as they grow and as the disk evolves. We model the temporal viscous evolution of a protoplanetary disk by coupling its dynamics, thermodynamics, geome...

High pH ammonia toxicity, and the search for life on the Jovian planets.

Science.gov (United States)

Deal, P H; Souza, K A; Mack, H M

1975-10-01

Jovian plants have enviroments apparently suitable for the evolution of life, but nevertheless, present severe challenges to organisms. One such challenge arises from the presence of ammonia. Ammonia is an efficient biocide, its effect being dependent on pH as well as on concentration. The effects of pH and ammonia concentration were studied separately, where possible, on a variety of organisms, including some isolated from natural enviornments of high pH and/or ammonia concentration. Escherichia coli and Bacillus subtilis are both extremely sensitive to ammonia. An aerobic organism (growth up to pH 11.4) from an alkaline spring is more resistant, but exhibits a toxic response to ammonia at a pH much lower than its maximum for growth. The greatest ammonia resistance has been found in an unidentified organism growing at near neutral pH. Even in this case, however, survival at ammonia concentrations reasonably expected on the Jovian planets is measured in hours. This is, nevertheless, two to three orders of magnitude longer than for E. coli. Our data support the tentative conclusion that contamination of the Jovian planets with terrestrial organisms that can grow is unlikely. However, the range of toxic response noted, coupled with the observation that terrestrial life has not been exposed to high ammonia concentrations for millions of years, suggests that adaptation to greater ammonia tolerance may be possible.

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 ...

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.…

2013; life is a cosmic phenomenon: the search for water evolves into the search for life

Science.gov (United States)

Smith, William E.

2013-09-01

The 2013 data from the Kepler Mission gives a current estimate of the number of Earth-like planets in the habitable zone of sun-like stars in the Milky Way Galaxy, as 144 billion. We propose that this estimate has caused a consciousness change in human belief in the probability of life off Earth. This seems to have affected NASA's public statements which are now leaning to the more visionary mission goal of the "Search for Life" rather than the 1975-2012 focus of the "Search for Water". We propose that the first confirmed Earth-like planet, expected to be announced later this year, be called "BORUCKI" in honour of the visionary USA scientist Bill Borucki, the father of the Kepler Mission. We explore the 2013 status of the Hoyle-Wickramasinghe Model of Panspermia, its hypothesis, propositions, experiments and evidence. We use the Karl Popper model for scientific hypotheses (1). Finally we explore Sir Fred Hoyle's vision of a planetary microbe defense system we call the Hoyle Shield. We explore the subsystem components of the shield and assess some options for these components using break-though technologies already available.

Variable Neighbourhood Search and Mathematical Programming for Just-in-Time Job-Shop Scheduling Problem

Directory of Open Access Journals (Sweden)

Sunxin Wang

2014-01-01

Full Text Available This paper presents a combination of variable neighbourhood search and mathematical programming to minimize the sum of earliness and tardiness penalty costs of all operations for just-in-time job-shop scheduling problem (JITJSSP. Unlike classical E/T scheduling problem with each job having its earliness or tardiness penalty cost, each operation in this paper has its earliness and tardiness penalties, which are paid if the operation is completed before or after its due date. Our hybrid algorithm combines (i a variable neighbourhood search procedure to explore the huge feasible solution spaces efficiently by alternating the swap and insertion neighbourhood structures and (ii a mathematical programming model to optimize the completion times of the operations for a given solution in each iteration procedure. Additionally, a threshold accepting mechanism is proposed to diversify the local search of variable neighbourhood search. Computational results on the 72 benchmark instances show that our algorithm can obtain the best known solution for 40 problems, and the best known solutions for 33 problems are updated.

Life Beyond the Planet of Origin and Implications for the Search for Life on Mars

Science.gov (United States)

Mancinelli, Rocco L.

2015-01-01

Outer space is vast, cold, devoid of matter, radiation filled with essentially no gravity. These factors present an environmental challenge for any form of life. Earth's biosphere has evolved for more than 3 billion years shielded from the hostile environment of outer space by the protective blanket of the atmosphere and magnetosphere. Space is a nutritional wasteland with no liquid water and readily available organic carbon. Moving beyond a life's planet of origin requires a means for transport, the ability to withstand transport, and the ability to colonize, thrive and ultimately evolve in the new environment. Can life survive beyond its home planet? The key to answering this question is to identify organisms that first have the ability to withstand space radiation, space vacuum desiccation and time in transit, and second the ability to grow in an alien environment. Within the last 60 years space technology allowed us to transport life beyond Earth's protective shield so we may study, in situ, their responses to selected conditions of space. To date a variety of microbes ranging from viruses, to Bacteria, to Archaea, to Eukarya have been tested in the space environment. Most died instantly, but not all. These studies revealed that ultraviolet radiation is the near-term lethal agent, while hard radiation is the long-term lethal agent when the organism is shielded from ultraviolet radiation. In fact, bacterial spores, halophilic cyanobacteria and Archaea as well as some lichens survive very well if protected from ultraviolet radiation [1]. Some microbes, then, may be able to survive the trip in outer space to Mars on a spacecraft or in a meteorite. Once on Mars can a terrestrial microbe survive? Although the conditions on Mars are not as harsh as those in space, they are not hospitable for a terrestrial microbe. Studies, however, have shown that certain microbes that can survive in space for several years may also be able to survive on Mars if protected from

YOUNG SOLAR SYSTEM's FIFTH GIANT PLANET?

International Nuclear Information System (INIS)

Nesvorný, David

2011-01-01

Studies of solar system formation suggest that the solar system's giant planets formed and migrated in the protoplanetary disk to reach the resonant orbits with all planets inside ∼15 AU from the Sun. After the gas disk's dispersal, Uranus and Neptune were likely scattered by the gas giants, and approached their current orbits while dispersing the transplanetary disk of planetesimals, whose remains survived to this time in the region known as the Kuiper Belt. Here we performed N-body integrations of the scattering phase between giant planets in an attempt to determine which initial states are plausible. We found that the dynamical simulations starting with a resonant system of four giant planets have a low success rate in matching the present orbits of giant planets and various other constraints (e.g., survival of the terrestrial planets). The dynamical evolution is typically too violent, if Jupiter and Saturn start in the 3:2 resonance, and leads to final systems with fewer than four planets. Several initial states stand out in that they show a relatively large likelihood of success in matching the constraints. Some of the statistically best results were obtained when assuming that the solar system initially had five giant planets and one ice giant, with the mass comparable to that of Uranus and Neptune, and which was ejected to interstellar space by Jupiter. This possibility appears to be conceivable in view of the recent discovery of a large number of free-floating planets in interstellar space, which indicates that planet ejection should be common.

Young Solar System's Fifth Giant Planet?

Science.gov (United States)

Nesvorný, David

2011-12-01

Studies of solar system formation suggest that the solar system's giant planets formed and migrated in the protoplanetary disk to reach the resonant orbits with all planets inside ~15 AU from the Sun. After the gas disk's dispersal, Uranus and Neptune were likely scattered by the gas giants, and approached their current orbits while dispersing the transplanetary disk of planetesimals, whose remains survived to this time in the region known as the Kuiper Belt. Here we performed N-body integrations of the scattering phase between giant planets in an attempt to determine which initial states are plausible. We found that the dynamical simulations starting with a resonant system of four giant planets have a low success rate in matching the present orbits of giant planets and various other constraints (e.g., survival of the terrestrial planets). The dynamical evolution is typically too violent, if Jupiter and Saturn start in the 3:2 resonance, and leads to final systems with fewer than four planets. Several initial states stand out in that they show a relatively large likelihood of success in matching the constraints. Some of the statistically best results were obtained when assuming that the solar system initially had five giant planets and one ice giant, with the mass comparable to that of Uranus and Neptune, and which was ejected to interstellar space by Jupiter. This possibility appears to be conceivable in view of the recent discovery of a large number of free-floating planets in interstellar space, which indicates that planet ejection should be common.

The circumstances of minor planet discovery

International Nuclear Information System (INIS)

Pilcher, F.

1989-01-01

The circumstances of discoveries of minor planets are presented in tabular form. Complete data are given for planets 2125-4044, together with notes pertaining to these planets. Information in the table includes the permanent number; the official name; for planets 330 and forward, the table includes the provisional designation attached to the discovery apparition and the year, month, the day of discovery, and the discovery place

The accretion of migrating giant planets

Science.gov (United States)

Dürmann, Christoph; Kley, Wilhelm

2017-02-01

Aims: Most studies concerning the growth and evolution of massive planets focus either on their accretion or their migration only. In this work we study both processes concurrently to investigate how they might mutually affect one another. Methods: We modeled a two-dimensional disk with a steady accretion flow onto the central star and embedded a Jupiter mass planet at 5.2 au. The disk is locally isothermal and viscosity is modeled using a constant α. The planet is held on a fixed orbit for a few hundred orbits to allow the disk to adapt and carve a gap. After this period, the planet is released and free to move according to the gravitational interaction with the gas disk. The mass accretion onto the planet is modeled by removing a fraction of gas from the inner Hill sphere, and the removed mass and momentum can be added to the planet. Results: Our results show that a fast migrating planet is able to accrete more gas than a slower migrating planet. Utilizing a tracer fluid we analyzed the origin of the accreted gas originating predominantly from the inner disk for a fast migrating planet. In the case of slower migration, the fraction of gas from the outer disk increases. We also found that even for very high accretion rates, in some cases gas crosses the planetary gap from the inner to the outer disk. Our simulations show that the crossing of gas changes during the migration process as the migration rate slows down. Therefore, classical type II migration where the planet migrates with the viscous drift rate and no gas crosses the gap is no general process but may only occur for special parameters and at a certain time during the orbital evolution of the planet.

Sequence Coding and Search System Backfit Quality Assurance Program Plan

International Nuclear Information System (INIS)

Lovell, C.J.; Stepina, P.L.

1985-03-01

The Sequence Coding and Search System is a computer-based encoding system for events described in Licensee Event Reports. This data system contains LERs from 1981 to present. Backfit of the data system to include LERs prior to 1981 is required. This report documents the Quality Assurance Program Plan that EG and G Idaho, Inc. will follow while encoding 1980 LERs

Detecting Close-In Extrasolar Giant Planets with the Kepler Photometer via Scattered Light

Science.gov (United States)

Jenkins, J. M.; Doyle, L. R.; Kepler Discovery Mission Team

2003-05-01

NASA's Kepler Mission will be launched in 2007 primarily to search for transiting Earth-sized planets in the habitable zones of solar-like stars. In addition, it will be poised to detect the reflected light component from close-in extrasolar giant planets (CEGPs) similar to 51 Peg b. Here we use the DIARAD/SOHO time series along with models for the reflected light signatures of CEGPs to evaluate Kepler's ability to detect such planets. We examine the detectability as a function of stellar brightness, stellar rotation period, planetary orbital inclination angle, and planetary orbital period, and then estimate the total number of CEGPs that Kepler will detect over its four year mission. The analysis shows that intrinsic stellar variability of solar-like stars is a major obstacle to detecting the reflected light from CEGPs. Monte Carlo trials are used to estimate the detection threshold required to limit the total number of expected false alarms to no more than one for a survey of 100,000 stellar light curves. Kepler will likely detect 100-760 51 Peg b-like planets by reflected light with orbital periods up to 7 days. LRD was supported by the Carl Sagan Chair at the Center for the Study of Life in the Universe, a division of the SETI Institute. JMJ received support from the Kepler Mission Photometer and Science Office at NASA Ames Research Center.

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.

Planet Hunters: Kepler by Eye

Science.gov (United States)

Schwamb, Megan E.; Lintott, C.; Fischer, D.; Smith, A. M.; Boyajian, T. S.; Brewer, J. M.; Giguere, M. J.; Lynn, S.; Parrish, M.; Schawinski, K.; Schmitt, J.; Simpson, R.; Wang, J.

2014-01-01

Planet Hunters (http://www.planethunters.org), part of the Zooniverse's (http://www.zooniverse.org) collection of online citizen science projects, uses the World Wide Web to enlist the general public to identify transits in the pubic Kepler light curves. Planet Hunters utilizes human pattern recognition to identify planet transits that may be missed by automated detection algorithms looking for periodic events. Referred to as ‘crowdsourcing’ or ‘citizen science’, the combined assessment of many non-expert human classifiers with minimal training can often equal or best that of a trained expert and in many cases outperform the best machine-learning algorithm. Visitors to the Planet Hunters' website are presented with a randomly selected ~30-day light curve segment from one of Kepler’s ~160,000 target stars and are asked to draw boxes to mark the locations of visible transits in the web interface. 5-10 classifiers review each 30-day light curve segment. Since December 2010, more than 260,000 volunteers world wide have participated, contributing over 20 million classifications. We have demonstrated the success of a citizen science approach with the project’s more than 20 planet candidates, the discovery of PH1b, a transiting circumbinary planet in a quadruple star system, and the discovery of PH2-b, a confirmed Jupiter-sized planet in the habitable zone of a Sun-like star. I will provide an overview of Planet Hunters, highlighting several of project's most recent exoplanet and astrophysical discoveries. Acknowledgements: MES was supported in part by a NSF AAPF under award AST-1003258 and a American Philosophical Society Franklin Grant. We acknowledge support from NASA ADAP12-0172 grant to PI Fischer.

WHY ARE PULSAR PLANETS RARE?

Energy Technology Data Exchange (ETDEWEB)

Martin, Rebecca G.; Livio, Mario; Palaniswamy, Divya [Department of Physics and Astronomy, University of Nevada, Las Vegas, 4505 South Maryland Parkway, Las Vegas, NV 89154 (United States)

2016-12-01

Pulsar timing observations have revealed planets around only a few pulsars. We suggest that the rarity of these planets is due mainly to two effects. First, we show that the most likely formation mechanism requires the destruction of a companion star. Only pulsars with a suitable companion (with an extreme mass ratio) are able to form planets. Second, while a dead zone (a region of low turbulence) in the disk is generally thought to be essential for planet formation, it is most probably rare in disks around pulsars, because of the irradiation from the pulsar. The irradiation strongly heats the inner parts of the disk, thus pushing the inner boundary of the dead zone out. We suggest that the rarity of pulsar planets can be explained by the low probability for these two requirements to be satisfied: a very low-mass companion and a dead zone.

Infrared radiation from an extrasolar planet.

Science.gov (United States)

Deming, Drake; Seager, Sara; Richardson, L Jeremy; Harrington, Joseph

2005-04-07

A class of extrasolar giant planets--the so-called 'hot Jupiters' (ref. 1)--orbit within 0.05 au of their primary stars (1 au is the Sun-Earth distance). These planets should be hot and so emit detectable infrared radiation. The planet HD 209458b (refs 3, 4) is an ideal candidate for the detection and characterization of this infrared light because it is eclipsed by the star. This planet has an anomalously large radius (1.35 times that of Jupiter), which may be the result of ongoing tidal dissipation, but this explanation requires a non-zero orbital eccentricity (approximately 0.03; refs 6, 7), maintained by interaction with a hypothetical second planet. Here we report detection of infrared (24 microm) radiation from HD 209458b, by observing the decrement in flux during secondary eclipse, when the planet passes behind the star. The planet's 24-microm flux is 55 +/- 10 microJy (1sigma), with a brightness temperature of 1,130 +/- 150 K, confirming the predicted heating by stellar irradiation. The secondary eclipse occurs at the midpoint between transits of the planet in front of the star (to within +/- 7 min, 1sigma), which means that a dynamically significant orbital eccentricity is unlikely.

Starting a Planet Protectors Club

Science.gov (United States)

US Environmental Protection Agency, 2007

2007-01-01

If your mission is to teach children how to reduce, reuse, and recycle waste and create the next generation of Planet Protectors, perhaps leading a Planet Protectors Club is part of your future challenges. You don't have to be an expert in waste reduction and recycling to lead a a Planet Protectors Club. You don't even have to be a teacher. You do…

Energy Consumption Forecasting Using Semantic-Based Genetic Programming with Local Search Optimizer

Directory of Open Access Journals (Sweden)

Mauro Castelli

2015-01-01

Full Text Available Energy consumption forecasting (ECF is an important policy issue in today’s economies. An accurate ECF has great benefits for electric utilities and both negative and positive errors lead to increased operating costs. The paper proposes a semantic based genetic programming framework to address the ECF problem. In particular, we propose a system that finds (quasi-perfect solutions with high probability and that generates models able to produce near optimal predictions also on unseen data. The framework blends a recently developed version of genetic programming that integrates semantic genetic operators with a local search method. The main idea in combining semantic genetic programming and a local searcher is to couple the exploration ability of the former with the exploitation ability of the latter. Experimental results confirm the suitability of the proposed method in predicting the energy consumption. In particular, the system produces a lower error with respect to the existing state-of-the art techniques used on the same dataset. More importantly, this case study has shown that including a local searcher in the geometric semantic genetic programming system can speed up the search process and can result in fitter models that are able to produce an accurate forecasting also on unseen data.

SEARCH: Study of Environmental Arctic Change—A System-scale, Cross-disciplinary Arctic Research Program

Science.gov (United States)

Wiggins, H. V.; Eicken, H.; Fox, S. E.

2012-12-01

SEARCH is an interdisciplinary and interagency program that works with academic and government agency scientists to plan, conduct, and synthesize studies of arctic change. The vision of SEARCH is to provide scientific understanding of arctic environmental change to help society understand and respond to a rapidly changing Arctic. Towards this end, SEARCH: 1. Generates and synthesizes research findings and promotes arctic science and scientific discovery across disciplines and among agencies. 2. Identifies emerging issues in arctic environmental change. 3. Provides information resources to arctic stakeholders, policy-makers, and the public to help them respond to arctic environmental change. 4. Coordinates with national arctic science programs integral to SEARCH goals. 5. Facilitates research activities across local-to-global scales with stakeholder concerns incorporated from the start of the planning process. 6. Represents the U.S. arctic environmental change science community in international and global change research initiatives. Specific current activities include: Arctic Observing Network (AON) - coordinating a system of atmospheric, land- and ocean-based environmental monitoring capabilities that will significantly advance our observations of arctic environmental conditions. Arctic Sea Ice Outlook ¬- an international effort that provides monthly summer reports synthesizing community estimates of the expected sea ice minimum. Sea Ice for Walrus Outlook - a resource for Alaska Native subsistence hunters, coastal communities, and others that provides weekly reports with information on sea ice conditions relevant to walrus in Alaska waters. In April, the SEARCH Science Steering Committee (SSC) released a set of draft 5-year goals and objectives for review by the broader arctic science community. The goals and objectives will direct the SEARCH program in the next five years. The draft SEARCH goals focus on four areas: ice-diminished Arctic Ocean, warming

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...

[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.

Evidence of an Upper Bound on the Masses of Planets and Its Implications for Giant Planet Formation

Science.gov (United States)

Schlaufman, Kevin C.

2018-01-01

Celestial bodies with a mass of M≈ 10 {M}{Jup} have been found orbiting nearby stars. It is unknown whether these objects formed like gas-giant planets through core accretion or like stars through gravitational instability. I show that objects with M≲ 4 {M}{Jup} orbit metal-rich solar-type dwarf stars, a property associated with core accretion. Objects with M≳ 10 {M}{Jup} do not share this property. This transition is coincident with a minimum in the occurrence rate of such objects, suggesting that the maximum mass of a celestial body formed through core accretion like a planet is less than 10 {M}{Jup}. Consequently, objects with M≳ 10 {M}{Jup} orbiting solar-type dwarf stars likely formed through gravitational instability and should not be thought of as planets. Theoretical models of giant planet formation in scaled minimum-mass solar nebula Shakura–Sunyaev disks with standard parameters tuned to produce giant planets predict a maximum mass nearly an order of magnitude larger. To prevent newly formed giant planets from growing larger than 10 {M}{Jup}, protoplanetary disks must therefore be significantly less viscous or of lower mass than typically assumed during the runaway gas accretion stage of giant planet formation. Either effect would act to slow the Type I/II migration of planetary embryos/giant planets and promote their survival. These inferences are insensitive to the host star mass, planet formation location, or characteristic disk dissipation time.

GLOBAL CHANGE RESEARCH NEWS #24: PUBLICATION OF FY2001 EDITION OF "OUR CHANGING PLANET"

Science.gov (United States)

The EPA Global Change Research Program is pleased to inform you of the publication of the new Our Changing Planet: The FY2001 U.S. Global Change Research Program. This annual report to the Congress was prepared under the auspices of the President's National Science and Technolog...

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

NIRCam Coronagraphic Observations of Disks and Planetary Systems

Science.gov (United States)

Beichman, Charles A.; Ygouf, Marie; Gaspar, Andras; NIRCam Science Team

2017-06-01

The NIRCam coronagraph offers a dramatic increase in sensitivity at wavelengths of 3-5 um where young planets are brightest. While large ground-based telescopes with Extreme Adaptive Optics have an advantage in inner working angle, NIRCam's sensitivity will allow high precision photometry for known planets and searches for planets with masses below that of Saturn. For debris disk science NIRCam observations will address the scattering properties of dust, look for evidence of ices and tholins, and search for planets which affect the structure of the disk itself.The NIRCam team's GTO program includes medium-band filter observations of known young planets having 1-5 Jupiter masses. A collaborative program with the MIRI team will provide coronagraphic observations at longer wavelengths. The combined dataset will yield the exoplanet’s total luminosity and effective temperature, an estimate of the initial entropy of the newly-formed planet, and the retrieval of atmospheric properties.The program will also make deep searches for lower mass planets toward known planetary systems, nearby young M stars and debris disk systems. Achievable mass limits range from ~1 Jupiter mass beyond 20 AU for the brightest A stars to perhaps a Uranus mass within 10 AU for the closest M stars.We will discuss details of the coronagraphic program for both the exoplanet and debris disk cases with an emphasis on using APT to optimize the observations of target and reference stars.

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.

Properties of the single Jovian planet population and the pursuit of Solar system analogues

Science.gov (United States)

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

2018-04-01

While the number of exoplanets discovered continues to increase at a rapid rate, we are still to discover any system that truly resembles the Solar system. Existing and near future surveys will likely continue this trend of rapid discovery. To see if these systems are Solar system analogues, we will need to efficiently allocate resources to carry out intensive follow-up observations. We seek to uncover the properties and trends across systems that indicate how much of the habitable zone is stable in each system to provide focus for planet hunters. We study the dynamics of all known single Jovian planetary systems, to assess the dynamical stability of the habitable zone around their host stars. We perform a suite of simulations of all systems where the Jovian planet will interact gravitationally with the habitable zone, and broadly classify these systems. Besides the system's mass ratio (Mpl/Mstar), and the Jovian planet's semi-major axis (apl) and eccentricity (epl), we find that there are no underlying system properties which are observable that indicate the potential for planets to survive within the system's habitable zone. We use Mpl/Mstar, apl and epl to generate a parameter space over which the unstable systems cluster, thus allowing us to predict which systems to exclude from future observational or numerical searches for habitable exoplanets. We also provide a candidate list of 20 systems that have completely stable habitable zones and Jovian planets orbiting beyond the habitable zone as potential first order Solar system analogues.

SMART-1 highlights and relevant studies on early bombardment and geological processes on rocky planets

International Nuclear Information System (INIS)

Foing, B H; Koschny, D; Frew, D; Almeida, M; Zender, J; Heather, D; Peters, S; Racca, G D; Marini, A; Stagnaro, L; Josset, J L; Beauvivre, S; Grande, M; Kellett, B; Huovelin, J; Nathues, A; Mall, U; Ehrenfreund, P; McCannon, P

2008-01-01

We present results from SMART-1 science and technology payload, in the context of the Nobel symposium on 'Physics of Planetary Systems'. SMART-1 is Europe' first lunar mission (Foing et al 2000 LPSC XXXI Abstract 1677 (CDROM); Foing et al 2001 Earth, Moon Planets 85-86 523-31; Marini et al 2002 Adv. Space Res. 30 1895-900; Racca et al 2001 Earth Moon Planets 85-86 379-95, Racca et al 2002 Planet Space Sci. 50 1323-37) demonstrating technologies for future science and exploration missions, and providing advances in our understanding of lunar origin and evolution, and general planetary questions. The mission also contributes a step in developing an international program of lunar exploration. The spacecraft, launched on 27 September 2003 as an Ariane 5 Auxiliary passenger to geostationary transfer orbit (GTO), performed a 14-month long cruise using a tiny thrust of electric propulsion alone, reached lunar capture in November 2004, and lunar science orbit in March 2005. SMART-1 carried 7 hardware experiments (Foing et al 2003 Adv. Space Res. 31 2323, Foing et al 2005 LPI/LPSC XXXVI 2404 (CDROM)) performing 10 investigations, including 3 remote-sensing instruments, used during the cruise, the mission' nominal six-months and one-year extension in lunar science orbit. Three remote sensing instruments, D-CIXS, SIR and AMIE, have returned data that are relevant to a broad range of lunar studies. The mission provided regional and global x-ray measurements of the Moon, global high-spectral resolution NIR spectrometry, high spatial resolution colour imaging of selected regions. The South Pole-Aitken Basin (SPA) and other impact basins have been prime targets for studies using the SMART-1 suite of instruments. Combined, these should aid a large number of science studies, from bulk crustal composition and theories of lunar origin/evolution, the global and local crustal composition, to the search for cold traps at the lunar poles and the mapping of potential lunar resources. We

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.

Scattering of exocomets by a planet chain: exozodi levels and the delivery of cometary material to inner planets

Science.gov (United States)

Marino, Sebastian; Bonsor, Amy; Wyatt, Mark C.; Kral, Quentin

2018-06-01

Exocomets scattered by planets have been invoked to explain observations in multiple contexts, including the frequently found near- and mid-infrared excess around nearby stars arising from exozodiacal dust. Here we investigate how the process of inward scattering of comets originating in an outer belt, is affected by the architecture of a planetary system, to determine whether this could lead to observable exozodi levels or deliver volatiles to inner planets. Using N-body simulations, we model systems with different planet mass and orbital spacing distributions in the 1-50 AU region. We find that tightly packed (Δap planets are the most efficient at delivering material to exozodi regions (5-7% of scattered exocomets end up within 0.5 AU at some point), although the exozodi levels do not vary by more than a factor of ˜7 for the architectures studied here. We suggest that emission from scattered dusty material in between the planets could provide a potential test for this delivery mechanism. We show that the surface density of scattered material can vary by two orders of magnitude (being highest for systems of low mass planets with medium spacing), whilst the exozodi delivery rate stays roughly constant, and that future instruments such as JWST could detect it. In fact for η Corvi, the current Herschel upper limit rules our the scattering scenario by a chain of ≲30 M⊕ planets. Finally, we show that exocomets could be efficient at delivering cometary material to inner planets (0.1-1% of scattered comets are accreted per inner planet). Overall, the best systems at delivering comets to inner planets are the ones that have low mass outer planets and medium spacing (˜20RH, m).

Evolutionary tracks of the terrestrial planets

International Nuclear Information System (INIS)

Matsui, Takafumi; Abe, Yutaka

1987-01-01

On the basis of the model proposed by Matsui and Abe, the authors show that two major factors - distance from the Sun and the efficiency of retention of accretional energy - control the early evolution of the terrestrial planets. A diagram of accretional energy versus the optical depth of a proto-atmosphere provides a means to follow the evolutionary track of surface temperature of the terrestrial planets and an explanation for why the third planet in our solar system is an 'aqua'-planet. 15 refs; 3 figs

Infrared radiation from an extrasolar planet

OpenAIRE

Deming, Drake; Seager, Sara; Richardson, L. Jeremy; Harrington, Joseph

2005-01-01

A class of extrasolar giant planets - the so-called `hot Jupiters' - orbit within 0.05 AU of their primary stars. These planets should be hot and so emit detectable infrared radiation. The planet HD 209458b is an ideal candidate for the detection and characterization of this infrared light because it is eclipsed by the star. This planet has an anomalously large radius (1.35 times that of Jupiter), which may be the result of ongoing tidal dissipation, but this explanation requires a non-zero o...

Kepler-22b: a 2.4 Earth-radius Planet in the Habitable Zone of a Sun-like Star

NARCIS (Netherlands)

Borucki, W.J.; Koch, D.G.; Batalha, N.; Bryson, S.T.; Rowe, J.; Fressin, F.; Torres, G.; Caldwell, D.A.; Christensen-Dalsgaard, J.; Cochran, W.D.; DeVore, E.; Gautier, T.N.; Geary, J.C.; Gilliland, R.; Gould, A.; Howell, S.B.; Jenkins, J.M.; Latham, D.W.; Lissauer, J.J.; Marcy, G.W.; Sasselov, D.; Boss, A.; Charbonneau, D.; Ciardi, D.; Kaltenegger, L.; Doyle, L.; Dupree, A.K.; Ford, E.B.; Fortney, J.; Holman, M.J.; Steffen, J.H.; Mullally, F.; Still, M.; Tarter, J.; Ballard, S.; Buchhave, L.A.; Carter, J.; Christiansen, J.L.; Demory, B.O.; Désert, J.M.; Dressing, C.; Endl, M.; Fabrycky, D.; Fischer, D.; Haas, M.R.; Henze, C.; Horch, E.; Howard, A.W.; Isaacson, H.; Kjeldsen, H.; Johnson, J.A.; Klaus, T.; Kolodziejczak, J.; Barclay, T.; Li, J.; Meibom, S.; Prsa, A.; Quinn, S.N.; Quintana, E.V.; Robertson, P.; Sherry, W.; Shporer, A.; Tenenbaum, P.; Thompson, S.E.; Twicken, J.D.; Van Cleve, J.; Welsh, W.F.; Basu, S.; Chaplin, W.; Miglio, A.; Kawaler, S.D.; Arentoft, T.; Stello, D.; Metcalfe, T.S.; Verner, G.A.; Karoff, C.; Lundkvist, M.; Lund, M.N.; Handberg, R.; Elsworth, Y.; Hekker, S.; Huber, D.; Bedding, T.R.; Rapin, W.

2012-01-01

A search of the time-series photometry from NASA's Kepler spacecraft reveals a transiting planet candidate orbiting the 11th magnitude G5 dwarf KIC 10593626 with a period of 290 days. The characteristics of the host star are well constrained by high-resolution spectroscopy combined with an

Debris disks as signposts of terrestrial planet formation. II. Dependence of exoplanet architectures on giant planet and disk properties

Science.gov (United States)

Raymond, S. N.; Armitage, P. J.; Moro-Martín, A.; Booth, M.; Wyatt, M. C.; Armstrong, J. C.; Mandell, A. M.; Selsis, F.; West, A. A.

2012-05-01

We present models for the formation of terrestrial planets, and the collisional evolution of debris disks, in planetary systems that contain multiple marginally unstable gas giants. We previously showed that in such systems, the dynamics of the giant planets introduces a correlation between the presence of terrestrial planets and cold dust, i.e., debris disks, which is particularly pronounced at λ ~ 70 μm. Here we present new simulations that show that this connection is qualitatively robust to a range of parameters: the mass distribution of the giant planets, the width and mass distribution of the outer planetesimal disk, and the presence of gas in the disk when the giant planets become unstable. We discuss how variations in these parameters affect the evolution. We find that systems with equal-mass giant planets undergo the most violent instabilities, and that these destroy both terrestrial planets and the outer planetesimal disks that produce debris disks. In contrast, systems with low-mass giant planets efficiently produce both terrestrial planets and debris disks. A large fraction of systems with low-mass (M ≲ 30 M⊕) outermost giant planets have final planetary separations that, scaled to the planets' masses, are as large or larger than the Saturn-Uranus and Uranus-Neptune separations in the solar system. We find that the gaps between these planets are not only dynamically stable to test particles, but are frequently populated by planetesimals. The possibility of planetesimal belts between outer giant planets should be taken into account when interpreting debris disk SEDs. In addition, the presence of ~ Earth-mass "seeds" in outer planetesimal disks causes the disks to radially spread to colder temperatures, and leads to a slow depletion of the outer planetesimal disk from the inside out. We argue that this may explain the very low frequency of >1 Gyr-old solar-type stars with observed 24 μm excesses. Our simulations do not sample the full range of

Online characterization of planetary surfaces: PlanetServer, an open-source analysis and visualization tool

Science.gov (United States)

Marco Figuera, R.; Pham Huu, B.; Rossi, A. P.; Minin, M.; Flahaut, J.; Halder, A.

2018-01-01

The lack of open-source tools for hyperspectral data visualization and analysis creates a demand for new tools. In this paper we present the new PlanetServer, a set of tools comprising a web Geographic Information System (GIS) and a recently developed Python Application Programming Interface (API) capable of visualizing and analyzing a wide variety of hyperspectral data from different planetary bodies. Current WebGIS open-source tools are evaluated in order to give an overview and contextualize how PlanetServer can help in this matters. The web client is thoroughly described as well as the datasets available in PlanetServer. Also, the Python API is described and exposed the reason of its development. Two different examples of mineral characterization of different hydrosilicates such as chlorites, prehnites and kaolinites in the Nili Fossae area on Mars are presented. As the obtained results show positive outcome in hyperspectral analysis and visualization compared to previous literature, we suggest using the PlanetServer approach for such investigations.

Kepler Confirmation of Multi-Planet Systems

Science.gov (United States)

Cochran, W. D.

2011-10-01

The NASA Kepler spacecraft has detected 170 candidate multi-planet systems in the first two quarters of data released in February 2011 by Borucki et al. (2011). These systems comprise 115 double candidate systems, 45 triple candidate sys- tems, and 10 systems with 4 or more candidate planets. The architecture and dynamics of these systems were discussed by Lissauer et al. (2011), and a comparison of candidates in single- and multi-planet systems was presented by Latham et al. (2011). Proceeding from "planetary candidate" systems to confirmed and validated multi-planet systems is a difficult process, as most of these systems orbit stars too faint to obtain extremely precise (1ms-1) radial velocity confimation. Here, we discuss in detail the use of transit timing vari- ations (cf. e.g. Holman et al., 2010) to confirm planets near a mean motion resonance. We also discuss extensions to the BLENDER validation (Torres et al., 2004, 2011; Fressin et al., 2011) to validate planets in multi-planet systems. Kepler was competitively selected as the tenth Discovery mission. Funding for the Kepler Mis- sion is provided by NASA's Science Mission Direc- torate. We are deeply grateful for the very hard work of the entire Kepler team.

TIDAL EVOLUTION OF CLOSE-IN PLANETS

International Nuclear Information System (INIS)

Matsumura, Soko; Rasio, Frederic A.; Peale, Stanton J.

2010-01-01

Recent discoveries of several transiting planets with clearly non-zero eccentricities and some large obliquities started changing the simple picture of close-in planets having circular and well-aligned orbits. The two major scenarios that form such close-in planets are planet migration in a disk and planet-planet interactions combined with tidal dissipation. The former scenario can naturally produce a circular and low-obliquity orbit, while the latter implicitly assumes an initially highly eccentric and possibly high-obliquity orbit, which are then circularized and aligned via tidal dissipation. Most of these close-in planets experience orbital decay all the way to the Roche limit as previous studies showed. We investigate the tidal evolution of transiting planets on eccentric orbits, and find that there are two characteristic evolution paths for them, depending on the relative efficiency of tidal dissipation inside the star and the planet. Our study shows that each of these paths may correspond to migration and scattering scenarios. We further point out that the current observations may be consistent with the scattering scenario, where the circularization of an initially eccentric orbit occurs before the orbital decay primarily due to tidal dissipation in the planet, while the alignment of the stellar spin and orbit normal occurs on a similar timescale to the orbital decay largely due to dissipation in the star. We also find that even when the stellar spin-orbit misalignment is observed to be small at present, some systems could have had a highly misaligned orbit in the past, if their evolution is dominated by tidal dissipation in the star. Finally, we also re-examine the recent claim by Levrard et al. that all orbital and spin parameters, including eccentricity and stellar obliquity, evolve on a similar timescale to orbital decay. This counterintuitive result turns out to have been caused by a typo in their numerical code. Solving the correct set of tidal

Planetesimals and Planet Formation

Science.gov (United States)

Chambers, John

The first step in the standard model for planet formation is the growth of gravitationally bound bodies called ``planetesimals'' from dust grains in a protoplanetary disk. Currently, we do not know how planetesimals form, how long they take to form, or what their sizes and mechanical properties are. The goal of this proposal is to assess how these uncertainties affect subsequent stages of planetary growth and the kind of planetary systems that form. The work will address three particular questions: (i) Can the properties of small body populations in the modern Solar System constrain the properties of planetesimals? (ii) How do the properties of planetesimals affect the formation of giant planets? (iii) How does the presence of a water ice condensation front (the ``snow line'') in a disk affect planetesimal formation and the later stages of planetary growth? These questions will be examined with computer simulations of planet formation using new computer codes to be developed as part of the proposal. The first question will be addressed using a statistical model for planetesimal coagulation and fragmentation. This code will be merged with the proposer's Mercury N-body integrator code to model the dynamics of large protoplanets in order to address the second question. Finally, a self- consistent model of disk evolution and the radial transport of water ice and vapour will be added to examine the third question. A theoretical understanding of how planets form is one of the key goals of NASA and the Origins of Solar Systems programme. Researchers have carried out many studies designed to address this goal, but the questions of how planetesimals form and how their properties affect planet formation have received relatively little attention. The proposed work will help address these unsolved questions, and place other research in context by assessing the importance of planetesimal origins and properties for planet formation.

THE OCCURRENCE RATE OF SMALL PLANETS AROUND SMALL STARS

International Nuclear Information System (INIS)

Dressing, Courtney D.; Charbonneau, David

2013-01-01

We use the optical and near-infrared photometry from the Kepler Input Catalog to provide improved estimates of the stellar characteristics of the smallest stars in the Kepler target list. We find 3897 dwarfs with temperatures below 4000 K, including 64 planet candidate host stars orbited by 95 transiting planet candidates. We refit the transit events in the Kepler light curves for these planet candidates and combine the revised planet/star radius ratios with our improved stellar radii to revise the radii of the planet candidates orbiting the cool target stars. We then compare the number of observed planet candidates to the number of stars around which such planets could have been detected in order to estimate the planet occurrence rate around cool stars. We find that the occurrence rate of 0.5-4 R ⊕ planets with orbital periods shorter than 50 days is 0.90 +0.04 -0.03 planets per star. The occurrence rate of Earth-size (0.5-1.4 R ⊕ ) planets is constant across the temperature range of our sample at 0.51 -0.05 +0.06 Earth-size planets per star, but the occurrence of 1.4-4 R ⊕ planets decreases significantly at cooler temperatures. Our sample includes two Earth-size planet candidates in the habitable zone, allowing us to estimate that the mean number of Earth-size planets in the habitable zone is 0.15 +0.13 -0.06 planets per cool star. Our 95% confidence lower limit on the occurrence rate of Earth-size planets in the habitable zones of cool stars is 0.04 planets per star. With 95% confidence, the nearest transiting Earth-size planet in the habitable zone of a cool star is within 21 pc. Moreover, the nearest non-transiting planet in the habitable zone is within 5 pc with 95% confidence.

LARGER PLANET RADII INFERRED FROM STELLAR ''FLICKER'' BRIGHTNESS VARIATIONS OF BRIGHT PLANET-HOST STARS

International Nuclear Information System (INIS)

Bastien, Fabienne A.; Stassun, Keivan G.; Pepper, Joshua

2014-01-01

Most extrasolar planets have been detected by their influence on their parent star, typically either gravitationally (the Doppler method) or by the small dip in brightness as the planet blocks a portion of the star (the transit method). Therefore, the accuracy with which we know the masses and radii of extrasolar planets depends directly on how well we know those of the stars, the latter usually determined from the measured stellar surface gravity, log g. Recent work has demonstrated that the short-timescale brightness variations ( f licker ) of stars can be used to measure log g to a high accuracy of ∼0.1-0.2 dex. Here, we use flicker measurements of 289 bright (Kepmag < 13) candidate planet-hosting stars with T eff = 4500-6650 K to re-assess the stellar parameters and determine the resulting impact on derived planet properties. This re-assessment reveals that for the brightest planet-host stars, Malmquist bias contaminates the stellar sample with evolved stars: nearly 50% of the bright planet-host stars are subgiants. As a result, the stellar radii, and hence the radii of the planets orbiting these stars, are on average 20%-30% larger than previous measurements had suggested

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...

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.

Volatile components and continental material of planets

International Nuclear Information System (INIS)

Florenskiy, K.P.; Nikolayeva, O.V.

1984-01-01

It is shown that the continental material of the terrestrial planets varies in composition from planet to planet according to the abundances and composition of true volatiles (H 2 0, CO 2 , etc.) in the outer shells of the planets. The formation of these shells occurs very early in a planet's evolution when the role of endogenous processes is indistinct and continental materials are subject to melting and vaporizing in the absence of an atmosphere. As a result, the chemical properties of continental materials are related not only to fractionation processes but also to meltability and volatility. For planets retaining a certain quantity of true volatile components, the chemical transformation of continental material is characterized by a close interaction between impact melting vaporization and endogeneous geological processes

Tracing Planets in Circumstellar Discs

Directory of Open Access Journals (Sweden)

Uribe Ana L.

2013-04-01

Full Text Available Planets are assumed to form in circumstellar discs around young stellar objects. The additional gravitational potential of a planet perturbs the disc and leads to characteristic structures, i.e. spiral waves and gaps, in the disc density profile. We perform a large-scale parameter study on the observability of these planet-induced structures in circumstellar discs in the (submm wavelength range for the Atacama Large (SubMillimeter Array (ALMA. On the basis of hydrodynamical and magneto-hydrodynamical simulations of star-disc-planet models we calculate the disc temperature structure and (submm images of these systems. These are used to derive simulated ALMA maps. Because appropriate objects are frequent in the Taurus-Auriga region, we focus on a distance of 140 pc and a declination of ≈ 20°. The explored range of star-disc-planet configurations consists of six hydrodynamical simulations (including magnetic fields and different planet masses, nine disc sizes with outer radii ranging from 9 AU to 225 AU, 15 total disc masses in the range between 2.67·10-7 M⊙ and 4.10·10-2 M⊙, six different central stars and two different grain size distributions, resulting in 10 000 disc models. At almost all scales and in particular down to a scale of a few AU, ALMA is able to trace disc structures induced by planet-disc interaction or the influence of magnetic fields in the wavelength range between 0.4...2.0 mm. In most cases, the optimum angular resolution is limited by the sensitivity of ALMA. However, within the range of typical masses of protoplane tary discs (0.1 M⊙...0.001 M⊙ the disc mass has a minor impact on the observability. At the distance of 140 pc it is possible to resolve discs down to 2.67·10-6 M⊙ and trace gaps in discs with 2.67·10-4 M⊙ with a signal-to-noise ratio greater than three. In general, it is more likely to trace planet-induced gaps in magneto-hydrodynamical disc models, because gaps are wider in the presence of

TWO SMALL PLANETS TRANSITING HD 3167

International Nuclear Information System (INIS)

Vanderburg, Andrew; Bieryla, Allyson; Latham, David W.; Mayo, Andrew W.; Berlind, Perry; Duev, Dmitry A.; Jensen-Clem, Rebecca; Kulkarni, Shrinivas; Riddle, Reed; Baranec, Christoph; Law, Nicholas M.; Nieberding, Megan N.; Salama, Maïssa

2016-01-01

We report the discovery of two super-Earth-sized planets transiting the bright (V = 8.94, K = 7.07) nearby late G-dwarf HD 3167, using data collected by the K2 mission. The inner planet, HD 3167 b, has a radius of 1.6 R ⊕ and an ultra-short orbital period of only 0.96 days. The outer planet, HD 3167 c, has a radius of 2.9 R ⊕ and orbits its host star every 29.85 days. At a distance of just 45.8 ± 2.2 pc, HD 3167 is one of the closest and brightest stars hosting multiple transiting planets, making HD 3167 b and c well suited for follow-up observations. The star is chromospherically inactive with low rotational line-broadening, ideal for radial velocity observations to measure the planets’ masses. The outer planet is large enough that it likely has a thick gaseous envelope that could be studied via transmission spectroscopy. Planets transiting bright, nearby stars like HD 3167 are valuable objects to study leading up to the launch of the James Webb Space Telescope .

Groupies and Loners: The Population of Multi-planet Systems

Science.gov (United States)

Van Laerhoven, Christa L.; Greenberg, Richard

2014-11-01

Observational surveys with Kepler and other telescopes have shown that multi-planet systems are very numerous. Considering the secular dynamcis of multi-planet systems provides substantial insight into the interactions between planets in those systems. Since the underlying secular structure of a multi-planet system (the secular eigenmodes) can be calculated using only the planets' masses and semi-major axes, one can elucidate the eccentricity and inclination behavior of planets in those systems even without knowing the planets' current eccentricities and inclinations. We have calculated both the eccentricity and inclination secular eigenmodes for the population of known multi-planet systems whose planets have well determined masses and periods. We will discuss the commonality of dynamically grouped planets ('groupies') vs dynamically uncoupled planets ('loners'), and compare to what would be expected from randomly generated systems with the same overall distribution of masses and semi-major axes. We will also discuss the occurrence of planets that strongly influence the behavior of other planets without being influenced by those others ('overlords'). Examples will be given and general trends will be discussed.

IESIP - AN IMPROVED EXPLORATORY SEARCH TECHNIQUE FOR PURE INTEGER LINEAR PROGRAMMING PROBLEMS

Science.gov (United States)

Fogle, F. R.

1994-01-01

IESIP, an Improved Exploratory Search Technique for Pure Integer Linear Programming Problems, addresses the problem of optimizing an objective function of one or more variables subject to a set of confining functions or constraints by a method called discrete optimization or integer programming. Integer programming is based on a specific form of the general linear programming problem in which all variables in the objective function and all variables in the constraints are integers. While more difficult, integer programming is required for accuracy when modeling systems with small numbers of components such as the distribution of goods, machine scheduling, and production scheduling. IESIP establishes a new methodology for solving pure integer programming problems by utilizing a modified version of the univariate exploratory move developed by Robert Hooke and T.A. Jeeves. IESIP also takes some of its technique from the greedy procedure and the idea of unit neighborhoods. A rounding scheme uses the continuous solution found by traditional methods (simplex or other suitable technique) and creates a feasible integer starting point. The Hook and Jeeves exploratory search is modified to accommodate integers and constraints and is then employed to determine an optimal integer solution from the feasible starting solution. The user-friendly IESIP allows for rapid solution of problems up to 10 variables in size (limited by DOS allocation). Sample problems compare IESIP solutions with the traditional branch-and-bound approach. IESIP is written in Borland's TURBO Pascal for IBM PC series computers and compatibles running DOS. Source code and an executable are provided. The main memory requirement for execution is 25K. This program is available on a 5.25 inch 360K MS DOS format diskette. IESIP was developed in 1990. IBM is a trademark of International Business Machines. TURBO Pascal is registered by Borland International.

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

"Osiris"(HD209458b), an evaporating planet

OpenAIRE

Vidal-Madjar, Alfred; Etangs, Alain Lecavelier des

2003-01-01

Three transits of the planet orbiting the solar type star HD209458 were observed in the far UV at the wavelength of the HI Ly-alpha line. The planet size at this wavelength is equal to 4.3 R_Jup, i.e. larger than the planet Roche radius (3.6 R_Jup). Absorbing hydrogen atoms were found to be blueshifted by up to -130 km/s, exceeding the planet escape velocity. This implies that hydrogen atoms are escaping this ``hot Jupiter'' planet. An escape flux of >~ 10^10g/s is needed to explain the obser...

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.

P-TYPE PLANET–PLANET SCATTERING: KEPLER CLOSE BINARY CONFIGURATIONS

International Nuclear Information System (INIS)

Gong, Yan-Xiang

2017-01-01

A hydrodynamical simulation shows that a circumbinary planet will migrate inward to the edge of the disk cavity. If multiple planets form in a circumbinary disk, successive migration will lead to planet–planet scattering (PPS). PPS of Kepler -like circumbinary planets is discussed in this paper. The aim of this paper is to answer how PPS affects the formation of these planets. We find that a close binary has a significant influence on the scattering process. If PPS occurs near the unstable boundary of a binary, about 10% of the systems can be completely destroyed after PPS. In more than 90% of the systems, there is only one planet left. Unlike the eccentricity distribution produced by PPS in a single star system, the surviving planets generally have low eccentricities if PPS take place near the location of the currently found circumbinary planets. In addition, the ejected planets are generally the innermost of two initial planets. The above results depend on the initial positions of the two planets. If the initial positions of the planets are moved away from the binary, the evolution tends toward statistics similar to those around single stars. In this process, the competition between the planet–planet force and the planet-binary force makes the eccentricity distribution of surviving planets diverse. These new features of P-type PPS will deepen our understanding of the formation of these circumbinary planets.

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.

Other Earths: Search for Life and the Constant Curvature

Directory of Open Access Journals (Sweden)

Khoshyaran M. M.

2015-07-01

Full Text Available The objective of this paper is to propose a search methodology for finding other exactly similar earth like planets (or sister earths. The theory is based on space consisting of Riemann curves or highways. A mathematical model based on constant curvature, a moving frame bundle, and gravitational dynamics is introduced.

Resonance capture and dynamics of three-planet systems

Science.gov (United States)

Charalambous, C.; Martí, J. G.; Beaugé, C.; Ramos, X. S.

2018-06-01

We present a series of dynamical maps for fictitious three-planet systems in initially circular coplanar orbits. These maps have unveiled a rich resonant structure involving two or three planets, as well as indicating possible migration routes from secular to double resonances or pure three-planet commensurabilities. These structures are then compared to the present-day orbital architecture of observed resonant chains. In a second part of the paper, we describe N-body simulations of type-I migration. Depending on the orbital decay time-scale, we show that three-planet systems may be trapped in different combinations of independent commensurabilities: (i) double resonances, (ii) intersection between a two-planet and a first-order three-planet resonances, and (iii) simultaneous libration in two first-order three-planet resonances. These latter outcomes are found for slow migrations, while double resonances are almost always the final outcome in high-density discs. Finally, we discuss an application to the TRAPPIST-1 system. We find that, for low migration rates and planetary masses of the order of the estimated values, most three-planet sub-systems are able to reach the observed double resonances after following evolutionary routes defined by pure three-planet resonances. The final orbital configuration shows resonance offsets comparable with present-day values without the need of tidal dissipation. For the 8/5 resonance proposed to dominate the dynamics of the two inner planets, we find little evidence of its dynamical significance; instead, we propose that this relation between mean motions could be a consequence of the interaction between a pure three-planet resonance and a two-planet commensurability between planets c and d.

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

Origin of the Earth and planets

International Nuclear Information System (INIS)

Safronov, V.S.; Ruskol, E.L.

1982-01-01

The present state of the Schmidt hypothesis on planets formation by combining cold solid particles and bodies in the protoplanet dust cloud is briefly outlined in a popular form. The most debatable problems of the planet cosmogony: formation of and processes in a protoplanet cloud, results of analytical evaluations and numerical simulation of origin of the Earth and planets-giants are discussed [ru

The search for our cosmic ancestry

CERN Document Server

Wickramasinghe, Chandra

2015-01-01

The idea that life is a cosmic, rather than a purely terrestrial phenomenon, has progressed from scientific heresy to mainstream science within the short timespan of a few decades. The theory of cometary panspermia developed by Fred Hoyle and the present author in the 1970's has been vindicated by a spate of new discoveries in astronomy and biology, and also with startling new evidence of microbial fossils in meteorites and micrometeorites. The recent Kepler Telescope searches for exoplanets have indicated the presence of over 100 billion habitable planets separated by only a few light years, thus making panspermia and the transfer of microbial life between such planets an inevitable fact. The book presents a comprehensive and up-to-date account of the Hoyle-Wickramasinghe theory of cometary panspermia in a manner accessible to a wide general readership.

Monitoring the High-Energy Radiation Environment of Exoplanets around Lowmass Stars with SPARCS (Star-Planet Activity Research CubeSat)

Science.gov (United States)

Shkolnik, Evgenya

Seventy-five billion M dwarfs in our galaxy host at least one small planet in the habitable zone (HZ). The stellar ultraviolet (UV) radiation from M dwarfs is strong and highly variable, and impacts planetary atmospheric loss, composition and habitability. These effects are amplified by the extreme proximity of their HZs (0.1–0.4 AU). JWST will characterize HZ M dwarf planets and attempt the first spectroscopic search for life beyond the Solar System. Knowing the UV environments of M dwarf planets will be crucial to understanding their atmospheric composition and a key parameter in discriminating between biological and abiotic sources for observed biosignatures. The UV flux emitted during the super-luminous premain sequence phase of M stars drives water loss and photochemical O2 buildup for terrestrial planets within the HZ. This phase can persist for up to a billion years for the lowest mass M stars. Afterwards, UV-driven photochemistry during the main sequence phase strongly affects a planet’s atmosphere, could limit the planet’s potential for habitability, and may confuse studies of habitability by creating false chemical biosignatures. Our proposed CubeSat observatory will be the first mission to provide the time-dependent spectral slope, intensity and evolution of M dwarf stellar UV radiation. These measurements are crucial to interpreting observations of planetary atmospheres around low-mass stars. Mission: The Star-Planet Activity Research CubeSat (SPARCS) will be a 6U CubeSat devoted to monitoring 25 M stars in two UV bands: SPARCS far-UV (S- FUV: 153–171 nm) and SPARCS near-UV (S-NUV: 260– 300 nm). For each target, SPARCS will observe continuously between one and three complete stellar rotations (4–45 days) over a mission lifetime of 2 years. A UV characterization survey of M dwarfs, the most common of planet hosts, is a perfect experiment for a CubeSat: - UV astronomy cannot be done from the ground because of Earth’s atmospheric absorption

Orbital Dynamics of Exomoons During Planet–Planet Scattering

Science.gov (United States)

Hong, Yu-Cian; Lunine, Jonathan I.; Nicholson, Philip; Raymond, Sean N.

2018-04-01

Planet–planet scattering is the leading mechanism to explain the broad eccentricity distribution of observed giant exoplanets. Here we study the orbital stability of primordial giant planet moons in this scenario. We use N-body simulations including realistic oblateness and evolving spin evolution for the giant planets. We find that the vast majority (~80%–90% across all our simulations) of orbital parameter space for moons is destabilized. There is a strong radial dependence, as moons past are systematically removed. Closer-in moons on Galilean-moon-like orbits (system, be captured by another planet, be ejected but still orbiting its free-floating host planet, or survive on heliocentric orbits as "planets." The survival rate of moons increases with the host planet mass but is independent of the planet's final (post-scattering) orbits. Based on our simulations, we predict the existence of an abundant galactic population of free-floating (former) moons.

Planets in Inuit Astronomy

Science.gov (United States)

MacDonald, John

2018-02-01

phenomenon of the "polar night." For several reasons, the role of planets in Inuit astronomy is difficult to determine, due, in part, to the characteristics of the planets themselves. Naked-eye differentiation between the major visible planets is by no means straightforward, and for observers living north of the Arctic Circle, the continuous or semicontinuous periods of daylight/twilight obtaining throughout the late spring, summer, and early fall effectively prevent year-round viewing of the night sky, making much planetary movement unobservable, far less an appreciation of the planets' predictable synodic and sidereal periods. Mitigating against the significant use of planets in Inuit culture is also the principle that their applied astronomy, along with its cosmology and mythologies depend principally on—apart from the sun and the moon—the predictability of the "fixed stars." Inuit of course did see the major planets and took note of them when they moved through their familiar asterisms or appeared, irregularly, as markers of solstice, or harbingers of daylight after winter's dark. Generally, however, planets seem to have been little regarded until after the introduction of Christianity, when, in parts of the Canadian eastern Arctic, Venus, in particular, became associated with Christmas. While there are anecdotal accounts that some of the planets, again especially Venus, may have had a place in Greenlandic mythology, this assertion is far from certain. Furthermore, reports from Alaska and Greenland suggesting that the appearance of Venus was a regular marker of the new year, or a predictor of sun's return, need qualification, given the apparent irregularity of Venus's appearances above the horizon. A survey of relevant literature, including oral history, pertaining either directly or peripherally to Inuit astronomical traditions, reveals few bona fide mention of planets. References to planets in Inuit mythology and astronomy are usually speculative, typically lacking

SILICON AND OXYGEN ABUNDANCES IN PLANET-HOST STARS

International Nuclear Information System (INIS)

Brugamyer, Erik; Dodson-Robinson, Sarah E.; Cochran, William D.; Sneden, Christopher

2011-01-01

The positive correlation between planet detection rate and host star iron abundance lends strong support to the core accretion theory of planet formation. However, iron is not the most significant mass contributor to the cores of giant planets. Since giant planet cores are thought to grow from silicate grains with icy mantles, the likelihood of gas giant formation should depend heavily on the oxygen and silicon abundance of the planet formation environment. Here we compare the silicon and oxygen abundances of a set of 76 planet hosts and a control sample of 80 metal-rich stars without any known giant planets. Our new, independent analysis was conducted using high resolution, high signal-to-noise data obtained at McDonald Observatory. Because we do not wish to simply reproduce the known planet-metallicity correlation, we have devised a statistical method for matching the underlying [Fe/H] distributions of our two sets of stars. We find a 99% probability that planet detection rate depends on the silicon abundance of the host star, over and above the observed planet-metallicity correlation. We do not detect any such correlation for oxygen. Our results would thus seem to suggest that grain nucleation, rather than subsequent icy mantle growth, is the important limiting factor in forming giant planets via core accretion. Based on our results and interpretation, we predict that planet detection should correlate with host star abundance for refractory elements responsible for grain nucleation and that no such trends should exist for the most abundant volatile elements responsible for icy mantle growth.

TWO SMALL PLANETS TRANSITING HD 3167

Energy Technology Data Exchange (ETDEWEB)

Vanderburg, Andrew; Bieryla, Allyson; Latham, David W.; Mayo, Andrew W.; Berlind, Perry [Harvard–Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Duev, Dmitry A.; Jensen-Clem, Rebecca; Kulkarni, Shrinivas; Riddle, Reed [California Institute of Technology, Pasadena, CA 91125 (United States); Baranec, Christoph [University of Hawai‘i at Mānoa, Hilo, HI 96720 (United States); Law, Nicholas M. [University of North Carolina at Chapel Hill, Chapel Hill, NC 27599 (United States); Nieberding, Megan N. [National Optical Astronomy Observatory, 950 N. Cherry Avenue, Tucson, AZ 85719 (United States); Salama, Maïssa, E-mail: avanderburg@cfa.harvard.edu [University of Hawai‘i at Mānoa, Honolulu, HI 96822 (United States)

2016-09-20

We report the discovery of two super-Earth-sized planets transiting the bright (V = 8.94, K = 7.07) nearby late G-dwarf HD 3167, using data collected by the K2 mission. The inner planet, HD 3167 b, has a radius of 1.6 R {sub ⊕} and an ultra-short orbital period of only 0.96 days. The outer planet, HD 3167 c, has a radius of 2.9 R {sub ⊕} and orbits its host star every 29.85 days. At a distance of just 45.8 ± 2.2 pc, HD 3167 is one of the closest and brightest stars hosting multiple transiting planets, making HD 3167 b and c well suited for follow-up observations. The star is chromospherically inactive with low rotational line-broadening, ideal for radial velocity observations to measure the planets’ masses. The outer planet is large enough that it likely has a thick gaseous envelope that could be studied via transmission spectroscopy. Planets transiting bright, nearby stars like HD 3167 are valuable objects to study leading up to the launch of the James Webb Space Telescope .

A New Way to Confirm Planet Candidates

Science.gov (United States)

Kohler, Susanna

2016-05-01

What was the big deal behind the Kepler news conference yesterday? Its not just that the number of confirmed planets found by Kepler has more than doubled (though thats certainly exciting news!). Whats especially interesting is the way in which these new planets were confirmed.Number of planet discoveries by year since 1995, including previous non-Kepler discoveries (blue), previous Kepler discoveries (light blue) and the newly validated Kepler planets (orange). [NASA Ames/W. Stenzel; Princeton University/T. Morton]No Need for Follow-UpBefore Kepler, the way we confirmed planet candidates was with follow-up observations. The candidate could be validated either by directly imaging (which is rare) or obtaining a large number radial-velocity measurements of the wobble of the planets host star due to the planets orbit. But once Kepler started producing planet candidates, these approaches to validation became less feasible. A lot of Kepler candidates are small and orbit faint stars, making follow-up observations difficult or impossible.This problem is what inspired the development of whats known as probabilistic validation, an analysis technique that involves assessing the likelihood that the candidates signal is caused by various false-positive scenarios. Using this technique allows astronomers to estimate the likelihood of a candidate signal being a true planet detection; if that likelihood is high enough, the planet candidate can be confirmed without the need for follow-up observations.A breakdown of the catalog of Kepler Objects of Interest. Just over half had previously been identified as false positives or confirmed as candidates. 1284 are newly validated, and another 455 have FPP of1090%. [Morton et al. 2016]Probabilistic validation has been used in the past to confirm individual planet candidates in Kepler data, but now Timothy Morton (Princeton University) and collaborators have taken this to a new level: they developed the first code thats designed to do fully

A TIDALLY DESTRUCTED MASSIVE PLANET AS THE PROGENITOR OF THE TWO LIGHT PLANETS AROUND THE sdB STAR KIC 05807616

International Nuclear Information System (INIS)

Bear, Ealeal; Soker, Noam

2012-01-01

We propose that the two newly detected Earth-size planets around the hot B subdwarf star KIC 05807616 are remnant of the tidally destructed metallic core of a massive planet. A single massive gas-giant planet was spiralling-in inside the envelope of the red giant branch star progenitor of the extreme horizontal branch (EHB) star KIC 05807616. The released gravitational energy unbound most of the stellar envelope, turning it into an EHB star. The massive planet reached the tidal-destruction radius of ∼1 R ☉ from the core, where the planet's gaseous envelope was tidally removed. In our scenario, the metallic core of the massive planet was tidally destructed into several Earth-like bodies immediately after the gaseous envelope of the planet was removed. Two, and possibly more, Earth-size fragments survived at orbital separations of ∼> 1 R ☉ within the gaseous disk. The bodies interact with the disk and among themselves, and migrated to reach orbits close to a 3:2 resonance. These observed planets can have a planetary magnetic field about 10 times as strong as that of Earth. This strong magnetic field can substantially reduce the evaporation rate from the planets and explain their survivability against the strong UV radiation of the EHB star.

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.

Motions on a rotating planet

Science.gov (United States)

Schröer, H.

In chapter 1 we want to describe the motion of a falling body on a rotating planet. The planet rotates with an arbitrary changable angular velocity and has a translational acceleration. We obtain 3 differential equations. For the general gravitational field an exact solution is possible, when the differential equation system is explicit solvable. Then we consider the case, if the angular velocity and the translational acceleration is constant. With a special transformation we get 3 partial differential equations of first order. Instead of a planet sphere we can choose a general body of rotation. Even general bodies are possible. Chapter 2 contains the motion in a local coordinate system on planet's surface. We have an inhomogeneous linear differential equation of first order. If the angular velocity is constant, we get a system with constant coefficients. There is an english and a german edition.

Survival Function Analysis of Planet Size Distribution

OpenAIRE

Zeng, Li; Jacobsen, Stein B.; Sasselov, Dimitar D.; Vanderburg, Andrew

2018-01-01

Applying the survival function analysis to the planet radius distribution of the Kepler exoplanet candidates, we have identified two natural divisions of planet radius at 4 Earth radii and 10 Earth radii. These divisions place constraints on planet formation and interior structure model. The division at 4 Earth radii separates small exoplanets from large exoplanets above. When combined with the recently-discovered radius gap at 2 Earth radii, it supports the treatment of planets 2-4 Earth rad...

EXTRASOLAR BINARY PLANETS. II. DETECTABILITY BY TRANSIT OBSERVATIONS

International Nuclear Information System (INIS)

Lewis, K. M.; Ida, S.; Ochiai, H.; Nagasawa, M.

2015-01-01

We discuss the detectability of gravitationally bound pairs of gas-giant planets (which we call “binary planets”) in extrasolar planetary systems that are formed through orbital instability followed by planet–planet dynamical tides during their close encounters, based on the results of N-body simulations by Ochiai et al. (Paper I). Paper I showed that the formation probability of a binary is as much as ∼10% for three giant planet systems that undergo orbital instability, and after post-capture long-term tidal evolution, the typical binary separation is three to five times the sum of the physical radii of the planets. The binary planets are stable during the main-sequence lifetime of solar-type stars, if the stellarcentric semimajor axis of the binary is larger than 0.3 AU. We show that detecting modulations of transit light curves is the most promising observational method to detect binary planets. Since the likely binary separations are comparable to the stellar diameter, the shape of the transit light curve is different from transit to transit, depending on the phase of the binary’s orbit. The transit durations and depth for binary planet transits are generally longer and deeper than those for the single planet case. We point out that binary planets could exist among the known inflated gas-giant planets or objects classified as false positive detections at orbital radii ≳0.3 AU, propose a binary planet explanation for the CoRoT candidate SRc01 E2 1066, and show that binary planets are likely to be present in, and could be detected using, Kepler-quality data

ABIOTIC O2 LEVELS ON PLANETS AROUND F, G, K, AND M STARS: POSSIBLE FALSE POSITIVES FOR LIFE?

International Nuclear Information System (INIS)

Harman, C. E.; Kasting, J. F.; Schwieterman, E. W.; Schottelkotte, J. C.

2015-01-01

In the search for life on Earth-like planets around other stars, the first (and likely only) information will come from the spectroscopic characterization of the planet's atmosphere. Of the countless number of chemical species terrestrial life produces, only a few have the distinct spectral features and the necessary atmospheric abundance to be detectable. The easiest of these species to observe in Earth's atmosphere is O 2 (and its photochemical byproduct, O 3 ). However, O 2 can also be produced abiotically by photolysis of CO 2 , followed by recombination of O atoms with each other. CO is produced in stoichiometric proportions. Whether O 2 and CO can accumulate to appreciable concentrations depends on the ratio of far-ultraviolet (FUV) to near-ultraviolet (NUV) radiation coming from the planet's parent star and on what happens to these gases when they dissolve in a planet's oceans. Using a one-dimensional photochemical model, we demonstrate that O 2 derived from CO 2 photolysis should not accumulate to measurable concentrations on planets around F- and G-type stars. K-star, and especially M-star planets, however, may build up O 2 because of the low NUV flux from their parent stars, in agreement with some previous studies. On such planets, a “false positive” for life is possible if recombination of dissolved CO and O 2 in the oceans is slow and if other O 2 sinks (e.g., reduced volcanic gases or dissolved ferrous iron) are small. O 3 , on the other hand, could be detectable at UV wavelengths (λ < 300 nm) for a much broader range of boundary conditions and stellar types

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

Science.gov (United States)

Duner, David

2013-05-01

In the seventeenth and eighteenth centuries it became possible to believe in the existence of life on other planets on scientific grounds. Once the Earth was no longer the center of the universe according to Copernicus, once Galileo had aimed his telescope at the Moon and found it a rough globe with mountains and seas, the assumption of life on other planets became much less far-fetched. In general there were no actual differences between Earth and Venus, since both planets orbited the Sun, were of similar size, and possessed mountains and an atmosphere. If there is life on Earth, one may ponder why it could not also exist on Venus. In the extraterrestrial life debate of the seventeenth and eighteenth centuries, the Moon, our closest celestial body, was the prime candidate for life on other worlds, although a number of scientists and scholars also speculated about life on Venus and on other planets, both within our solar system and beyond its frontiers. This chapter discusses the arguments for life on Venus and those scientific findings that were used to support them, which were based in particular on assumptions and claims that both mountains and an atmosphere had been found on Venus. The transits of Venus in the 1760s became especially important for the notion that life could thrive on Venus. Here, I detect two significant cognitive processes that were at work in the search for life on Venus, i.e., analogical reasoning and epistemic perception, while analogies and interpretations of sensory impressions based on prior knowledge played an important role in astrobiological theories.

The most conserved genome segments for life detection on Earth and other planets.

Science.gov (United States)

Isenbarger, Thomas A; Carr, Christopher E; Johnson, Sarah Stewart; Finney, Michael; Church, George M; Gilbert, Walter; Zuber, Maria T; Ruvkun, Gary

2008-12-01

On Earth, very simple but powerful methods to detect and classify broad taxa of life by the polymerase chain reaction (PCR) are now standard practice. Using DNA primers corresponding to the 16S ribosomal RNA gene, one can survey a sample from any environment for its microbial inhabitants. Due to massive meteoritic exchange between Earth and Mars (as well as other planets), a reasonable case can be made for life on Mars or other planets to be related to life on Earth. In this case, the supremely sensitive technologies used to study life on Earth, including in extreme environments, can be applied to the search for life on other planets. Though the 16S gene has become the standard for life detection on Earth, no genome comparisons have established that the ribosomal genes are, in fact, the most conserved DNA segments across the kingdoms of life. We present here a computational comparison of full genomes from 13 diverse organisms from the Archaea, Bacteria, and Eucarya to identify genetic sequences conserved across the widest divisions of life. Our results identify the 16S and 23S ribosomal RNA genes as well as other universally conserved nucleotide sequences in genes encoding particular classes of transfer RNAs and within the nucleotide binding domains of ABC transporters as the most conserved DNA sequence segments across phylogeny. This set of sequences defines a core set of DNA regions that have changed the least over billions of years of evolution and provides a means to identify and classify divergent life, including ancestrally related life on other planets.

Mastering Search Analytics Measuring SEO, SEM and Site Search

CERN Document Server

Chaters, Brent

2011-01-01

Many companies still approach Search Engine Optimization (SEO) and paid search as separate initiatives. This in-depth guide shows you how to use these programs as part of a comprehensive strategy-not just to improve your site's search rankings, but to attract the right people and increase your conversion rate. Learn how to measure, test, analyze, and interpret all of your search data with a wide array of analytic tools. Gain the knowledge you need to determine the strategy's return on investment. Ideal for search specialists, webmasters, and search marketing managers, Mastering Search Analyt

Planets around the evolved stars 24 Boötis and γ Libra: A 30 d-period planet and a double giant-planet system in possible 7:3 MMR

Science.gov (United States)

Takarada, Takuya; Sato, Bun'ei; Omiya, Masashi; Harakawa, Hiroki; Nagasawa, Makiko; Izumiura, Hideyuki; Kambe, Eiji; Takeda, Yoichi; Yoshida, Michitoshi; Itoh, Yoichi; Ando, Hiroyasu; Kokubo, Eiichiro; Ida, Shigeru

2018-05-01

We report the detection of planets around two evolved giant stars from radial velocity measurements at Okayama Astrophysical observatory. 24 Boo (G3 IV) has a mass of 0.99 M_{⊙}, a radius of 10.64 R_{⊙}, and a metallicity of [Fe/H] = -0.77. The star hosts one planet with a minimum mass of 0.91 MJup and an orbital period of 30.35 d. The planet has one of the shortest orbital periods among those ever found around evolved stars using radial-velocity methods. The stellar radial velocities show additional periodicity with 150 d, which can probably be attributed to stellar activity. The star is one of the lowest-metallicity stars orbited by planets currently known. γ Lib (K0 III) is also a metal-poor giant with a mass of 1.47 M_{⊙}, a radius of 11.1 R_{⊙}, and [Fe/H] = -0.30. The star hosts two planets with minimum masses of 1.02 MJup and 4.58 MJup, and periods of 415 d and 964 d, respectively. The star has the second-lowest metallicity among the giant stars hosting more than two planets. Dynamical stability analysis for the γ Lib system sets the minimum orbital inclination angle to be about 70° and suggests that the planets are in 7:3 mean-motion resonance, though the current best-fitting orbits for the radial-velocity data are not totally regular.

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.

Constraining the volatile fraction of planets from transit observations

Science.gov (United States)

Alibert, Y.

2016-06-01

Context. The determination of the abundance of volatiles in extrasolar planets is very important as it can provide constraints on transport in protoplanetary disks and on the formation location of planets. However, constraining the internal structure of low-mass planets from transit measurements is known to be a degenerate problem. Aims: Using planetary structure and evolution models, we show how observations of transiting planets can be used to constrain their internal composition, in particular the amount of volatiles in the planetary interior, and consequently the amount of gas (defined in this paper to be only H and He) that the planet harbors. We first explore planets that are located close enough to their star to have lost their gas envelope. We then concentrate on planets at larger distances and show that the observation of transiting planets at different evolutionary ages can provide statistical information on their internal composition, in particular on their volatile fraction. Methods: We computed the evolution of low-mass planets (super-Earths to Neptune-like) for different fractions of volatiles and gas. We used a four-layer model (core, silicate mantle, icy mantle, and gas envelope) and computed the internal structure of planets for different luminosities. With this internal structure model, we computed the internal and gravitational energy of planets, which was then used to derive the time evolution of the planet. Since the total energy of a planet depends on its heat capacity and density distribution and therefore on its composition, planets with different ice fractions have different evolution tracks. Results: We show for low-mass gas-poor planets that are located close to their central star that assuming evaporation has efficiently removed the entire gas envelope, it is possible to constrain the volatile fraction of close-in transiting planets. We illustrate this method on the example of 55 Cnc e and show that under the assumption of the absence of

ECCENTRIC JUPITERS VIA DISK–PLANET INTERACTIONS

International Nuclear Information System (INIS)

Duffell, Paul C.; Chiang, Eugene

2015-01-01

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

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...

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...

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

MIGRATION OF PLANETS EMBEDDED IN A CIRCUMSTELLAR DISK

International Nuclear Information System (INIS)

Bromley, Benjamin C.; Kenyon, Scott J.

2011-01-01

Planetary migration poses a serious challenge to theories of planet formation. In gaseous and planetesimal disks, migration can remove planets as quickly as they form. To explore migration in a planetesimal disk, we combine analytic and numerical approaches. After deriving general analytic migration rates for isolated planets, we use N-body simulations to confirm these results for fast and slow migration modes. Migration rates scale as m -1 (for massive planets) and (1 + (e H /3) 3 ) -1 , where m is the mass of a planet and e H is the eccentricity of the background planetesimals in Hill units. When multiple planets stir the disk, our simulations yield the new result that large-scale migration ceases. Thus, growing planets do not migrate through planetesimal disks. To extend these results to migration in gaseous disks, we compare physical interactions and rates. Although migration through a gaseous disk is an important issue for the formation of gas giants, we conclude that migration has little impact on the formation of terrestrial planets.

The Institute on Climate and Planets (ICP): A Research Education Program

Science.gov (United States)

Carlson, Barbara (Technical Monitor)

2003-01-01

Giving students a fair start to become productive and responsible contributors in the 21st century workforce and society depends on our ability to help them develop: (1) A global view of the world; (2) Problem-solving and/or reasoning abilities; (3) Basic scientific and technical literacy; and (4) A multi-disciplinary understanding of how humans and nature interact with the earth system. The Institute on Climate and Planets (ICP) in New York City is NASA Goddard Institute for Space Studies' (GISS) response to the national challenge to give students a fair start to become productive in America's workforce and society, GISS is part of the Earth Science Director at NASA Goddard Space Flight Center in Maryland and a component of Columbia University's Earth Institute, a university-wide initiative whose mission is to understand our planet so as to enhance its sustainability. In 1994 Jim Hansen, several of his GISS and Columbia University colleagues and Fitzgerald Bramwell, the former Director of the New York City Alliance for Minority Participation at City University of New York, launched the ICP. ICP contributes to NASA education and minority outreach goals by directly involving underrepresented college, high school and junior high school students and their educators in research. ICP takes advantage of the interest of many civil servants and Columbia University research scientists at GISS to involve students and educators on multi-level research teams working on problems at the core of NASA's Earth Science Enterprise - advancing our understanding of Earth s climate, climate variability, and climate impacts.

Planet Formation

Science.gov (United States)

Podolak, Morris

2018-04-01

Modern observational techniques are still not powerful enough to directly view planet formation, and so it is necessary to rely on theory. However, observations do give two important clues to the formation process. The first is that the most primitive form of material in interstellar space exists as a dilute gas. Some of this gas is unstable against gravitational collapse, and begins to contract. Because the angular momentum of the gas is not zero, it contracts along the spin axis, but remains extended in the plane perpendicular to that axis, so that a disk is formed. Viscous processes in the disk carry most of the mass into the center where a star eventually forms. In the process, almost as a by-product, a planetary system is formed as well. The second clue is the time required. Young stars are indeed observed to have gas disks, composed mostly of hydrogen and helium, surrounding them, and observations tell us that these disks dissipate after about 5 to 10 million years. If planets like Jupiter and Saturn, which are very rich in hydrogen and helium, are to form in such a disk, they must accrete their gas within 5 million years of the time of the formation of the disk. Any formation scenario one proposes must produce Jupiter in that time, although the terrestrial planets, which don't contain significant amounts of hydrogen and helium, could have taken longer to build. Modern estimates for the formation time of the Earth are of the order of 100 million years. To date there are two main candidate theories for producing Jupiter-like planets. The core accretion (CA) scenario supposes that any solid materials in the disk slowly coagulate into protoplanetary cores with progressively larger masses. If the core remains small enough it won't have a strong enough gravitational force to attract gas from the surrounding disk, and the result will be a terrestrial planet. If the core grows large enough (of the order of ten Earth masses), and the disk has not yet dissipated, then

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.

A review of the US Global Change Research Program and NASA's Mission to Planet Earth/Earth Observing System

Science.gov (United States)

Moore, Berrien, III; Anderson, James G.; Costanza, Robert; Gates, W. Lawrence; Grew, Priscilla C.; Leinen, Margaret S.; Mayewski, Paul A.; McCarthy, James J.; Sellers, Piers J.

1995-01-01

This report reflects the results of a ten-day workshop convened at the Scripps Institution of Oceanography July 19-28, 1995. The workshop was convened as the first phase of a two part review of the U.S. Global Change Research Program (USGCRP). The workshop was organized to provide a review of the scientific foundations and progress to date in the USGCRP and an assessment of the implications of new scientific insights for future USGCRP and Mission to Planet Earth/Earth Observing System (MTPE/EOS) activities; a review of the role of NASA's MTPE/EOS program in the USGCRP observational strategy; a review of the EOS Data and Information System (EOSDIS) as a component of USGCRP data management activities; and an assessment of whether recent developments in the following areas lead to a need to readjust MTPE/EOS plans. Specific consideration was given to: proposed convergence of U.S. environmental satellite systems and programs, evolving international plans for Earth observation systems, advances in technology, and potential expansion of the role of the private sector. The present report summarizes the findings and recommendations developed by the Committee on Global Change Research on the basis of the presentations, background materials, working group deliberations, and plenary discussions of the workshop. In addition, the appendices include summaries prepared by the six working groups convened in the course of the workshop.

About the Linguistic Impossibility of Claiming that Small Planets are not Planets

Science.gov (United States)

Nedeljkovic, A. B.

2012-12-01

Philology, which is, the science of language and literature, must now offer assistance to the science of astronomy, about one question of terminology and logic. Namely, if something belongs to one category, then it is, regardless of its size (large, or medium, or small) a member of that category. Therefore, it was linguistically wrong to claim that Pluto is one of the dwarf planets and therefore not a planet. This mistake, much noticed by the world's public opinion, ought to be corrected immediately.

The search for extraterrestrial life: Recent developments; Proceedings of the Symposium, Boston University, MA, June 18-21, 1984

Science.gov (United States)

Papagiannis, M. D.

The conference presents papers on the history of the search for extraterrestrial life, the scientific rationale and methods used in the search for other planetary systems, the detection of distant planets with the Space Telescope, planetary searches using optical astrometric interferometers, and infrared spectral identification of complex organic molecules in interstellar grains. Also considered are universal protein ancestors from hydrogen cyanide and water, astronomical sources of polarized light and their role in determining molecular chirality on earth, the universal diagrams and life in the universe, the precambrian evolution of terrestrial life and a thermodynamic approach to the occurrance and appearance of galactic life forms. Papers are also presented on the Ohio Seti program, lunar reflections of terrestrial radio leakage, the multichannel spectrum analyzer, software implementation of detection algorithms for the MCSA, the Serendip II design, galactic colonization and competition in a young galactic disk, implications of ancient and future migrations, extraterrestrial intelligence, the inevitability and the possible structures of supercivilizations, planetary, interplanetary and interstellar organic matter, and universal aspects of biological evolution.

Searching for Exoplanets using Artificial Intelligence

Science.gov (United States)

Pearson, Kyle Alexander; Palafox, Leon; Griffith, Caitlin Ann

2017-10-01

In the last decade, over a million stars were monitored to detect transiting planets. The large volume of data obtained from current and future missions (e.g. Kepler, K2, TESS and LSST) requires automated methods to detect the signature of a planet. Manual interpretation of potential exoplanet candidates is labor intensive and subject to human error, the results of which are difficult to quantify. Here we present a new method of detecting exoplanet candidates in large planetary search projects which, unlike current methods uses a neural network. Neural networks, also called ``deep learning'' or ``deep nets'', are a state of the art machine learning technique designed to give a computer perception into a specific problem by training it to recognize patterns. Unlike past transit detection algorithms, the deep net learns to characterize the data instead of relying on hand-coded metrics that humans perceive as the most representative. Exoplanet transits have different shapes, as a result of, e.g. the planet's and stellar atmosphere and transit geometry. Thus, a simple template does not suffice to capture the subtle details, especially if the signal is below the noise or strong systematics are present. Current false-positive rates from the Kepler data are estimated around 12.3% for Earth-like planets and there has been no study of the false negative rates. It is therefore important to ask how the properties of current algorithms exactly affect the results of the Kepler mission and, future missions such as TESS, which flies next year. These uncertainties affect the fundamental research derived from missions, such as the discovery of habitable planets, estimates of their occurrence rates and our understanding about the nature and evolution of planetary systems.

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,

The 76Ge Program to Search for Neutrinoless Double-Beta Decay

Science.gov (United States)

Guiseppe, Vincente

2017-09-01

Neutrinoless double-beta decay searches play a major role in determining the nature of neutrinos, the existence of a lepton violating process, and the effective Majorana neutrino mass. The Majorana and Gerda Collaborations are operating arrays of high purity Ge detectors to search for neutrinoless double-beta decay in 76Ge. The Majorana Demonstrator is operating at the Sanford Underground Research Facility in South Dakota while the Gerda experiment is operating at LNGS in Italy. The Gerda and Majorana Demonstrator experiments have achieved the lowest backgrounds in the neutrinoless double-beta decay region of interest. These results, coupled with the superior energy resolution (0.1%) of Ge detectors demonstrate that 76Ge is an ideal isotope for a large next generation experiment. The LEGEND collaboration, with 220 members from 47 institutions around the world, has been formed to pursue a ton scale 76Ge experiment. Building on the successes of Gerda and Majorana, the LEGEND collaboration aims to develop a phased neutrinoless double-beta decay experimental program with discovery potential at a half-life significantly longer than 1027 years. This talk will present the initial results from the Majorana Demonstrator and Gerda experiments and the plan for the LEGEND program.

Kepler Planet Detection Metrics: Per-Target Flux-Level Transit Injection Tests of TPS for Data Release 25

Science.gov (United States)

Burke, Christopher J.; Catanzarite, Joseph

2017-01-01

Quantifying the ability of a transiting planet survey to recover transit signals has commonly been accomplished through Monte-Carlo injection of transit signals into the observed data and subsequent running of the signal search algorithm (Gilliland et al., 2000; Weldrake et al., 2005; Burke et al., 2006). In order to characterize the performance of the Kepler pipeline (Twicken et al., 2016; Jenkins et al., 2017) on a sample of over 200,000 stars, two complementary injection and recovery tests are utilized:1. Injection of a single transit signal per target into the image or pixel-level data, hereafter referred to as pixel-level transit injection (PLTI), with subsequent processing through the Photometric Analysis (PA), Presearch Data Conditioning (PDC), Transiting Planet Search (TPS), and Data Validation (DV) modules of the Kepler pipeline. The PLTI quantification of the Kepler pipeline's completeness has been described previously by Christiansen et al. (2015, 2016); the completeness of the final SOC 9.3 Kepler pipeline acting on the Data Release 25 (DR25) light curves is described by Christiansen (2017).2. Injection of multiple transit signals per target into the normalized flux time series data with a subsequent transit search using a stream-lined version of the Transiting Planet Search (TPS) module. This test, hereafter referred to as flux-level transit injection (FLTI), is the subject of this document. By running a heavily modified version of TPS, FLTI is able to perform many injections on selected targets and determine in some detail which injected signals are recoverable. Significant numerical efficiency gains are enabled by precomputing the data conditioning steps at the onset of TPS and limiting the search parameter space (i.e., orbital period, transit duration, and ephemeris zero-point) to a small region around each injected transit signal.The PLTI test has the advantage that it follows transit signals through all processing steps of the Kepler pipeline, and

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

Observability of planet-disc interactions in CO kinematics

Science.gov (United States)

Pérez, Sebastián; Casassus, S.; Benítez-Llambay, P.

2018-06-01

Empirical evidence of planets in gas-rich circumstellar discs is required to constrain giant planet formation theories. Here we study the kinematic patterns which arise from planet-disc interactions and their observability in CO rotational emission lines. We perform three-dimensional hydrodynamical simulations of single giant planets, and predict the emergent intensity field with radiative transfer. Pressure gradients at planet-carved gaps, spiral wakes and vortices bear strong kinematic counterparts. The iso-velocity contours in the CO(2-1) line centroids vo reveal large-scale perturbations, corresponding to abrupt transitions from below sub-Keplerian to super-Keplerian rotation along with radial and vertical flows. The increase in line optical depth at the edge of the gap also modulates vo, but this is a mild effect compared to the dynamical imprint of the planet-disc interaction. The large-scale deviations from the Keplerian rotation thus allow the planets to be indirectly detected via the first moment maps of molecular gas tracers, at ALMA angular resolutions. The strength of these deviations depends on the mass of the perturber. This initial study paves the way to eventually determine the mass of the planet by comparison with more detailed models.

Radio images of the planets

International Nuclear Information System (INIS)

De Pater, I.

1990-01-01

Observations at radio wavelengths make possible detailed studies of planetary atmospheres, magnetospheres, and surface layers. The paper addresses the question of what can be learned from interferometric radio images of planets. Results from single-element radio observations are also discussed. Observations of both the terrestrial and the giant planets are considered. 106 refs

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.

BIOME: A scientific data archive search-and-order system using browser-aware, dynamic pages

Science.gov (United States)

Jennings, S. V.; Yow, T. G.; Ng, V. W.

1997-01-01

The Oak Ridge National Laboratory's (ORNL) Distributed Active Archive Center (DAAC) is a data archive and distribution center for the National Air and Space Administration's (NASA) Earth Observing System Data and Information System (EOSDIS). Both the Earth Observing System (EOS) and EOSDIS are components of NASA's contribution to the US Global Change Research Program through its Mission to Planet Earth Program. The ORNL DAAC provides access to data used in ecological and environmental research such as global change, global warming, and terrestrial ecology. Because of its large and diverse data holdings, the challenge for the ORNL DAAC is to help users find data of interest from the hundreds of thousands of files available at the DAAC without overwhelming them. Therefore, the ORNL DAAC has developed the Biogeochemical Information Ordering Management Environment (BIOME), a customized search and order system for the World Wide Web (WWW). BIOME is a public system located at http://www-eosdis. ornl.gov/BIOME/biome.html.

Results from occultations by minor planets

International Nuclear Information System (INIS)

Taylor, G.E.

1982-01-01

Since the minor planets are believed to consist of primordial matter dating from the time of the formation of the solar system there is great interest in determining their composition. It is therefore necessary to calculate their densities, for which we need accurate masses and sizes. On the rare occasions when a minor planet occults a star, timed observations of the event from a number of observing sites enable an accurate size of the minor planet to be determined. (Auth.)

SEARCHING FOR PLANETS IN HOLEY DEBRIS DISKS WITH THE APODIZING PHASE PLATE

International Nuclear Information System (INIS)

Meshkat, Tiffany; Kenworthy, Matthew A.; Bailey, Vanessa P.; Su, Kate Y. L.; Hinz, Philip M.; Smith, Paul S.; Mamajek, Eric E.

2015-01-01

We present our first results from a high-contrast imaging search for planetary mass companions around stars with gapped debris disks, as inferred from the stars' bright infrared excesses. For the six considered stars, we model the disks' unresolved infrared spectral energy distributions in order to derive the temperature and location of the disk components. With VLT/NaCo Apodizing Phase Plate coronagraphic L'-band imaging, we search for planetary mass companions that may be sculpting the disks. We detect neither disks nor companions in this sample, confirmed by comparing plausible point sources with archival data. In order to calculate our mass sensitivity limit, we revisit the stellar age estimates. One target, HD 17848, at 540 ± 100 Myr old is significantly older than previously estimated. We then discuss our high-contrast imaging results with respect to the disk properties

SEARCHING FOR PLANETS IN HOLEY DEBRIS DISKS WITH THE APODIZING PHASE PLATE

Energy Technology Data Exchange (ETDEWEB)

Meshkat, Tiffany; Kenworthy, Matthew A. [Sterrewacht Leiden, P.O. Box 9513, Niels Bohrweg 2, 2300 RA Leiden (Netherlands); Bailey, Vanessa P.; Su, Kate Y. L.; Hinz, Philip M.; Smith, Paul S. [Steward Observatory, Department of Astronomy, University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721-0065 (United States); Mamajek, Eric E. [Department of Physics and Astronomy, University of Rochester, Rochester, NY 14627-0171 (United States)

2015-02-10

We present our first results from a high-contrast imaging search for planetary mass companions around stars with gapped debris disks, as inferred from the stars' bright infrared excesses. For the six considered stars, we model the disks' unresolved infrared spectral energy distributions in order to derive the temperature and location of the disk components. With VLT/NaCo Apodizing Phase Plate coronagraphic L'-band imaging, we search for planetary mass companions that may be sculpting the disks. We detect neither disks nor companions in this sample, confirmed by comparing plausible point sources with archival data. In order to calculate our mass sensitivity limit, we revisit the stellar age estimates. One target, HD 17848, at 540 ± 100 Myr old is significantly older than previously estimated. We then discuss our high-contrast imaging results with respect to the disk properties.

Modeling circumbinary planets: The case of Kepler-38

Science.gov (United States)

Kley, Wilhelm; Haghighipour, Nader

2014-04-01

Context. Recently, a number of planets orbiting binary stars have been discovered by the Kepler space telescope. In a few systems the planets reside close to the dynamical stability limit. Owing to the difficulty of forming planets in such close orbits, it is believed that they have formed farther out in the disk and migrated to their present locations. Aims: Our goal is to construct more realistic models of planet migration in circumbinary disks and to determine the final position of these planets more accurately. In our work, we focus on the system Kepler-38 where the planet is close to the stability limit. Methods: The evolution of the circumbinary disk is studied using two-dimensional hydrodynamical simulations. We study locally isothermal disks as well as more realistic models that include full viscous heating, radiative cooling from the disk surfaces, and radiative diffusion in the disk midplane. After the disk has been brought into a quasi-equilibrium state, a 115 Earth-mass planet is embedded and its evolution is followed. Results: In all cases the planets stop inward migration near the inner edge of the disk. In isothermal disks with a typical disk scale height of H/r = 0.05, the final outcome agrees very well with the observed location of planet Kepler-38b. For the radiative models, the disk thickness and location of the inner edge is determined by the mass in the system. For surface densities on the order of 3000 g/cm2 at 1 AU, the inner gap lies close to the binary and planets stop in the region between the 5:1 and 4:1 mean-motion resonances with the binary. A model with a disk with approximately a quarter of the mass yields a final position very close to the observed one. Conclusions: For planets migrating in circumbinary disks, the final position is dictated by the structure of the disk. Knowing the observed orbits of circumbinary planets, radiative disk simulations with embedded planets can provide important information on the physical state of the