Photoelectic BV Light Curves of Algol and the Interpretations of the Light Curves

Directory of Open Access Journals (Sweden)

Ho-Il Kim

1985-06-01

Full Text Available Standardized B and V photoelectric light curves of Algol are made with the observations obtained during 1982-84 with the 40-cm and the 61-cm reflectors of Yonsei University Observatory. These light curves show asymmetry between ascending and descending shoulders. The ascending shoulder is 0.02 mag brighter than descending shoulder in V light curve and 0.03 mag in B light curve. These asymmetric light curves are interpreted as the result of inhomogeneous energy distribution on the surface of one star of the eclipsing pair rather than the result of gaseous stream flowing from KOIV to B8V star. The 180-year periodicity, so called great inequality, are most likely the result proposed by Kim et al. (1983 that the abrupt and discrete mass losses of cooler component may be the cause of this orbital change. The amount of mass loss deduced from these discrete period changes turned out to be of the order of 10^(-6 - 10^(-5 Msolar.

An Alternate Light Curve Solution of AR Lacertae

Directory of Open Access Journals (Sweden)

Hong Suh Park

1984-09-01

Full Text Available Photoelectric UBV light curves of AR Lacertae made in one season during 1981-82 are presented. Although the shape of the light curves in the outside eclipses show a strong distortion, the scatter of observations as well as phase coverage are better than those previously available. Fourier coefficients are derived from the V-light curve and observed curve successfully rectified to the Russell model. Light curve solutions are computed and the geometrical and physical parameters of AR Lac are derived as as = 0.812, ag = 0.341, j = 86°3, Ls = 0.372, Lg = 0.628, k = 0.53, Xs = 0.85, Xg = 0.4.

Orbital Light Curves of UU Aquarii in Stunted Outburst

Science.gov (United States)

Robertson, J. W.; Honeycutt, R. K.; Henden, A. A.; Campbell, R. T.

2018-02-01

Stunted outbursts are ∼0.ͫ6 eruptions, typically lasting 5–10 days, which are found in some novalike cataclysmic variables, including UU Aqr. The mechanism responsible for stunted outbursts is uncertain but is likely related to an accretion disk instability or to variations in the mass transfer rate. A campaign to monitor the eclipse light curves in UU Aqr has been conducted in order to detect any light curve distortions due to the appearance of a hot spot on the disk at the location of the impact point of the accretion stream. If stunted outbursts are due to a temporary mass transfer enhancement, then predictable deformations of the orbital light curve are expected to occur during such outbursts. This study used 156 eclipses on 135 nights during the years 2000–2012. During this interval, random samples found the system to be in stunted outbursts 4%–5% of the time, yielding ∼7 eclipses obtained during some stage of stunted outburst. About half of the eclipses obtained during stunted outbursts showed clear evidence for hot spot enhancement, providing strong evidence that the stunted outbursts in UU Aqr are associated with mass transfer variations. The other half of the eclipses during stunted outburst showed little or no evidence for hot spot enhancement. Furthermore, there were no systematic changes in the hot spot signature as stunted outbursts progressed. Therefore, we have tentatively attributed the changes in hot spot visibility during stunted outburst to random blobby accretion, which likely further modulates the strength of the accretion stream on orbital timescales.

Kepler eclipsing binary stars. IV. Precise eclipse times for close binaries and identification of candidate three-body systems

International Nuclear Information System (INIS)

Conroy, Kyle E.; Stassun, Keivan G.; Prša, Andrej; Orosz, Jerome A.; Welsh, William F.; Fabrycky, Daniel C.

2014-01-01

We present a catalog of precise eclipse times and analysis of third-body signals among 1279 close binaries in the latest Kepler Eclipsing Binary Catalog. For these short-period binaries, Kepler's 30 minute exposure time causes significant smearing of light curves. In addition, common astrophysical phenomena such as chromospheric activity, as well as imperfections in the light curve detrending process, can create systematic artifacts that may produce fictitious signals in the eclipse timings. We present a method to measure precise eclipse times in the presence of distorted light curves, such as in contact and near-contact binaries which exhibit continuously changing light levels in and out of eclipse. We identify 236 systems for which we find a timing variation signal compatible with the presence of a third body. These are modeled for the light travel time effect and the basic properties of the third body are derived. This study complements J. A. Orosz et al. (in preparation), which focuses on eclipse timing variations of longer period binaries with flat out-of-eclipse regions. Together, these two papers provide comprehensive eclipse timings for all binaries in the Kepler Eclipsing Binary Catalog, as an ongoing resource freely accessible online to the community.

A Composite Light Curve Model of the Symbiotic Nova PU Vul (1979

Directory of Open Access Journals (Sweden)

Kato M.

2012-06-01

Full Text Available PU Vul (1979 is a symbiotic nova that shows a long-lasting flat optical peak followed by a slow decline. We made a quasi-evolution model for outbursts on a 0.6 M⊙ white dwarf consisting of a series of static solutions with optically-thin winds. Our theoretical models reproduce well the observed visual/UV light curves as well as the new estimates of the temperature and radius of the hot component. We also modeled the light curve of the 1980 and 1994 eclipses as the total eclipse occulted by a pulsating M-giant companion star. In the second eclipse, the visual magnitude is dominated by nebular emission which is possibly ejected from the hot component between 1990 to 2000. We have quantitatively estimated three components of emission, i.e., the white dwarf, companion and nebular, and made a composite light curve that represents well the evolution of the PU Vul outburst.

AN X-RAY AND OPTICAL LIGHT CURVE MODEL OF THE ECLIPSING SYMBIOTIC BINARY SMC3

International Nuclear Information System (INIS)

Kato, Mariko; Hachisu, Izumi; Mikołajewska, Joanna

2013-01-01

Some binary evolution scenarios for Type Ia supernovae (SNe Ia) include long-period binaries that evolve to symbiotic supersoft X-ray sources in their late stage of evolution. However, symbiotic stars with steady hydrogen burning on the white dwarf's (WD) surface are very rare, and the X-ray characteristics are not well known. SMC3 is one such rare example and a key object for understanding the evolution of symbiotic stars to SNe Ia. SMC3 is an eclipsing symbiotic binary, consisting of a massive WD and red giant (RG), with an orbital period of 4.5 years in the Small Magellanic Cloud. The long-term V light curve variations are reproduced as orbital variations in the irradiated RG, whose atmosphere fills its Roche lobe, thus supporting the idea that the RG supplies matter to the WD at rates high enough to maintain steady hydrogen burning on the WD. We also present an eclipse model in which an X-ray-emitting region around the WD is almost totally occulted by the RG swelling over the Roche lobe on the trailing side, although it is always partly obscured by a long spiral tail of neutral hydrogen surrounding the binary in the orbital plane.

NEAR-INFRARED LIGHT CURVES OF THE BROWN DWARF ECLIPSING BINARY 2MASS J05352184-0546085: CAN SPOTS EXPLAIN THE TEMPERATURE REVERSAL?

International Nuclear Information System (INIS)

Gomez Maqueo Chew, Yilen; Stassun, Keivan G.; Prsa, Andrej; Mathieu, Robert D.

2009-01-01

We present near-infrared JHK S light curves for the double-lined eclipsing binary system Two Micron All Sky Survey J05352184 - 0546085, in which both components have been shown to be brown dwarfs with an age of ∼1 Myr. We analyze these light curves together with the previously published I C -band light curve and radial velocities to provide refined measurements of the system's physical parameters. The component masses and radii are here determined with an accuracy of ∼6.5% and ∼1.5%, respectively. In addition, we confirm the previous surprising finding that the primary brown dwarf has a cooler effective temperature than its lower mass companion. Next, we perform a detailed study of the residual variations in the out-of-eclipse phases of the light curves to ascertain the properties of any inhomogeneities (e.g., spots) on the surfaces of the brown dwarfs. Our analysis reveals two low-amplitude (∼0.02 mag) periodic signals, one attributable to the rotation of the primary with a period of 3.293 ± 0.001 d and the other to the rotation of the secondary with a period of 14.05 ± 0.05 d. Both periods are consistent with the measured vsin i and radii. Finally, we explore the effects on the derived physical parameters of the system when spots are included in the modeling of the light curves. The observed low-amplitude rotational modulations are well fitted by cool spots covering a small fraction (∼<10%) of the brown dwarfs' surfaces. Such small spots negligibly affect the physical properties of the brown dwarfs, and thus by themselves cannot explain the primary's unexpectedly low surface temperature. To mimic the observed ∼200 K suppression of the primary's temperature, our model requires that the primary possesses a very large spot coverage fraction of ∼65%. These spots must in addition be symmetrically distributed on the primary's surface so as not to produce photometric variations larger than observed. Altogether, a spot configuration in which the primary

Observations and light curve solutions of the eclipsing binaries USNO-B1.0 1395-0370184 and USNO-B1.0 1395-0370731

Directory of Open Access Journals (Sweden)

Kjurkchieva D.

2016-01-01

Full Text Available We present follow-up photometric observations in Sloan filters g', i' of the newly discovered eclipsing stars USNO-B1.0 1395-0370184 and USNO-B1.0 1395-0370731. Our data revealed that their orbital periods are considerably bigger than the previous values. This result changed the classification of USNO-B1.0 1395-0370184 from ultrashort-period binary (P=0.197 d to short-period system (P=0.251 d. The light curve solutions of our observations revealed that USNOB1.0 1395-0370184 and USNO-B1.0 1395-0370731 are overcontact binaries in which components are K dwarfs, close in masses and radii. The light curve distortions were reproduced by cool spots with angular radius of around 20°.

B and V photoelectric photometry and light curve solution of the interacting binary systems HI Puppis, BL Eridani and SY Horologii

International Nuclear Information System (INIS)

Kern, J.R.

1985-01-01

The first photoelectric observations of the eclipsing binary systems HI Puppis, BL Eridani, and SY Horologii were obtained and complete B and V light curves are presented. Improved light elements were derived for all three systems. The light curves of HI Puppis were analyzed by the three different computer models of Wilson and Devinney (1971), Binnendijk (1977), and Wood (1971) to get the geometrical and photometric elements of the system. HI Puppis, whose light curves show a total eclipse at secondary minimum, is shown to be a classic A-Type W Ursae Majoris system. The geometrical and photometric elements of BL Eridani were obtained from the analysis of the light curves using the method of Wilson and Devinney. The asymmetric nature of the light curve is treated as being due to the presence of an underluminous starspot on the primary component. The light curves of BL Eri show secondary eclipse to be total. The system is found to be a near contact system with the primary component filling its Roche lobe and the secondary nearly filling its lobe with a fill-out ratio of approximately 1.0. The light curves of SY Horologii were also subjected to the model of Wilson and Devinney. Both primary and secondary eclipses are partial

Hot spot manifestation in eclipsing dwarf nova HT Cassiopeiae

OpenAIRE

Bakowska, K.; Olech, A.

2014-01-01

We report the detection of the hot spot in light curves of the eclipsing dwarf nova HT Cassiopeiae during its superoutburst in 2010 November. Analysis of eight reconstructed light curves of the hot spot eclipses showed directly that the brightness of the hot spot was changing significantly during the superoutburst. Thereby, detected hot spot manifestation in HT Cas is the newest observational evidence for the EMT model for dwarf novae.

Spectral Eclipse Timing

Science.gov (United States)

Dobbs-Dixon, Ian; Agol, Eric; Deming, Drake

2015-12-01

We utilize multi-dimensional simulations of varying equatorial jet strength to predict wavelength-dependent variations in the eclipse times of gas-giant planets. A displaced hot spot introduces an asymmetry in the secondary eclipse light curve that manifests itself as a measured offset in the timing of the center of eclipse. A multi-wavelength observation of secondary eclipse, one probing the timing of barycentric eclipse at short wavelengths and another probing at longer wavelengths, will reveal the longitudinal displacement of the hot spot and break the degeneracy between this effect and that associated with the asymmetry due to an eccentric orbit. The effect of time offsets was first explored in the IRAC wavebands by Williams et al. Here we improve upon their methodology, extend to a broad range of wavelengths, and demonstrate our technique on a series of multi-dimensional radiative-hydrodynamical simulations of HD 209458b with varying equatorial jet strength and hot-spot displacement. Simulations with the largest hot-spot displacement result in timing offsets of up to 100 s in the infrared. Though we utilize a particular radiative hydrodynamical model to demonstrate this effect, the technique is model independent. This technique should allow a much larger survey of hot-spot displacements with the James Webb Space Telescope than currently accessible with time-intensive phase curves, hopefully shedding light on the physical mechanisms associated with thermal energy advection in irradiated gas giants.

SPECTRAL ECLIPSE TIMING

International Nuclear Information System (INIS)

Dobbs-Dixon, Ian; Agol, Eric; Deming, Drake

2015-01-01

We utilize multi-dimensional simulations of varying equatorial jet strength to predict wavelength-dependent variations in the eclipse times of gas-giant planets. A displaced hot spot introduces an asymmetry in the secondary eclipse light curve that manifests itself as a measured offset in the timing of the center of eclipse. A multi-wavelength observation of secondary eclipse, one probing the timing of barycentric eclipse at short wavelengths and another probing at longer wavelengths, will reveal the longitudinal displacement of the hot spot and break the degeneracy between this effect and that associated with the asymmetry due to an eccentric orbit. The effect of time offsets was first explored in the IRAC wavebands by Williams et al. Here we improve upon their methodology, extend to a broad range of wavelengths, and demonstrate our technique on a series of multi-dimensional radiative-hydrodynamical simulations of HD 209458b with varying equatorial jet strength and hot-spot displacement. Simulations with the largest hot-spot displacement result in timing offsets of up to 100 s in the infrared. Though we utilize a particular radiative hydrodynamical model to demonstrate this effect, the technique is model independent. This technique should allow a much larger survey of hot-spot displacements with the James Webb Space Telescope than currently accessible with time-intensive phase curves, hopefully shedding light on the physical mechanisms associated with thermal energy advection in irradiated gas giants

SPECTRAL ECLIPSE TIMING

Energy Technology Data Exchange (ETDEWEB)

Dobbs-Dixon, Ian [Department of Physics, NYU Abu Dhabi P.O. Box 129188 Abu Dhabi (United Arab Emirates); Agol, Eric [Department of Astronomy, University of Washington, Seattle WA 98195 (United States); Deming, Drake [NASA Astrobiology Institute Virtual Planet Laboratory (United States)

2015-12-10

We utilize multi-dimensional simulations of varying equatorial jet strength to predict wavelength-dependent variations in the eclipse times of gas-giant planets. A displaced hot spot introduces an asymmetry in the secondary eclipse light curve that manifests itself as a measured offset in the timing of the center of eclipse. A multi-wavelength observation of secondary eclipse, one probing the timing of barycentric eclipse at short wavelengths and another probing at longer wavelengths, will reveal the longitudinal displacement of the hot spot and break the degeneracy between this effect and that associated with the asymmetry due to an eccentric orbit. The effect of time offsets was first explored in the IRAC wavebands by Williams et al. Here we improve upon their methodology, extend to a broad range of wavelengths, and demonstrate our technique on a series of multi-dimensional radiative-hydrodynamical simulations of HD 209458b with varying equatorial jet strength and hot-spot displacement. Simulations with the largest hot-spot displacement result in timing offsets of up to 100 s in the infrared. Though we utilize a particular radiative hydrodynamical model to demonstrate this effect, the technique is model independent. This technique should allow a much larger survey of hot-spot displacements with the James Webb Space Telescope than currently accessible with time-intensive phase curves, hopefully shedding light on the physical mechanisms associated with thermal energy advection in irradiated gas giants.

SPIDERMAN: an open-source code to model phase curves and secondary eclipses

Science.gov (United States)

Louden, Tom; Kreidberg, Laura

2018-03-01

We present SPIDERMAN (Secondary eclipse and Phase curve Integrator for 2D tempERature MAppiNg), a fast code for calculating exoplanet phase curves and secondary eclipses with arbitrary surface brightness distributions in two dimensions. Using a geometrical algorithm, the code solves exactly the area of sections of the disc of the planet that are occulted by the star. The code is written in C with a user-friendly Python interface, and is optimised to run quickly, with no loss in numerical precision. Approximately 1000 models can be generated per second in typical use, making Markov Chain Monte Carlo analyses practicable. The modular nature of the code allows easy comparison of the effect of multiple different brightness distributions for the dataset. As a test case we apply the code to archival data on the phase curve of WASP-43b using a physically motivated analytical model for the two dimensional brightness map. The model provides a good fit to the data; however, it overpredicts the temperature of the nightside. We speculate that this could be due to the presence of clouds on the nightside of the planet, or additional reflected light from the dayside. When testing a simple cloud model we find that the best fitting model has a geometric albedo of 0.32 ± 0.02 and does not require a hot nightside. We also test for variation of the map parameters as a function of wavelength and find no statistically significant correlations. SPIDERMAN is available for download at https://github.com/tomlouden/spiderman.

SPIDERMAN: an open-source code to model phase curves and secondary eclipses

Science.gov (United States)

Louden, Tom; Kreidberg, Laura

2018-06-01

We present SPIDERMAN (Secondary eclipse and Phase curve Integrator for 2D tempERature MAppiNg), a fast code for calculating exoplanet phase curves and secondary eclipses with arbitrary surface brightness distributions in two dimensions. Using a geometrical algorithm, the code solves exactly the area of sections of the disc of the planet that are occulted by the star. The code is written in C with a user-friendly Python interface, and is optimized to run quickly, with no loss in numerical precision. Approximately 1000 models can be generated per second in typical use, making Markov Chain Monte Carlo analyses practicable. The modular nature of the code allows easy comparison of the effect of multiple different brightness distributions for the data set. As a test case, we apply the code to archival data on the phase curve of WASP-43b using a physically motivated analytical model for the two-dimensional brightness map. The model provides a good fit to the data; however, it overpredicts the temperature of the nightside. We speculate that this could be due to the presence of clouds on the nightside of the planet, or additional reflected light from the dayside. When testing a simple cloud model, we find that the best-fitting model has a geometric albedo of 0.32 ± 0.02 and does not require a hot nightside. We also test for variation of the map parameters as a function of wavelength and find no statistically significant correlations. SPIDERMAN is available for download at https://github.com/tomlouden/spiderman.

Physics of Eclipsing Binaries: Motivation for the New-Age Modeling Suite

OpenAIRE

Pavlovski, K.; Prša, A.; Degroote, P.; Conroy, K.; Bloemen, S.; Hambleton, Kelly; Giammarco, J.; Pablo, H.; Tkachenko, A.; Torres, G.

2013-01-01

Recent ultra-high precision observations of eclipsing binaries, especially data acquired by the Kepler satellite, have made accurate light curve modelling increasingly challenging but also more rewarding. In this contribution, we discuss low-amplitude signals in light curves that can now be used to derive physical information about eclipsing binaries but that were unaccessible before the Kepler era. A notable example is the detection of Doppler beaming, which leads to an increase in flux when...

EXPLORING THE VARIABLE SKY WITH LINEAR. III. CLASSIFICATION OF PERIODIC LIGHT CURVES

Energy Technology Data Exchange (ETDEWEB)

Palaversa, Lovro; Eyer, Laurent; Rimoldini, Lorenzo [Observatoire Astronomique de l' Université de Genève, 51 chemin des Maillettes, CH-1290 Sauverny (Switzerland); Ivezić, Željko; Loebman, Sarah; Hunt-Walker, Nicholas; VanderPlas, Jacob; Westman, David; Becker, Andrew C. [Department of Astronomy, University of Washington, P.O. Box 351580, Seattle, WA 98195-1580 (United States); Ruždjak, Domagoj; Sudar, Davor; Božić, Hrvoje [Hvar Observatory, Faculty of Geodesy, Kačićeva 26, 10000 Zagreb (Croatia); Galin, Mario [Faculty of Geodesy, Kačićeva 26, 10000 Zagreb (Croatia); Kroflin, Andrea; Mesarić, Martina; Munk, Petra; Vrbanec, Dijana [Department of Physics, Faculty of Science, University of Zagreb, Bijenička cesta 32, 10000 Zagreb (Croatia); Sesar, Branimir [Division of Physics, Mathematics, and Astronomy, Caltech, Pasadena, CA 91125 (United States); Stuart, J. Scott [Lincoln Laboratory, Massachusetts Institute of Technology, 244 Wood Street, Lexington, MA 02420-9108 (United States); Srdoč, Gregor, E-mail: lovro.palaversa@unige.ch [Saršoni 90, 51216 Viškovo (Croatia); and others

2013-10-01

We describe the construction of a highly reliable sample of ∼7000 optically faint periodic variable stars with light curves obtained by the asteroid survey LINEAR across 10,000 deg{sup 2} of the northern sky. The majority of these variables have not been cataloged yet. The sample flux limit is several magnitudes fainter than most other wide-angle surveys; the photometric errors range from ∼0.03 mag at r = 15 to ∼0.20 mag at r = 18. Light curves include on average 250 data points, collected over about a decade. Using Sloan Digital Sky Survey (SDSS) based photometric recalibration of the LINEAR data for about 25 million objects, we selected ∼200,000 most probable candidate variables with r < 17 and visually confirmed and classified ∼7000 periodic variables using phased light curves. The reliability and uniformity of visual classification across eight human classifiers was calibrated and tested using a catalog of variable stars from the SDSS Stripe 82 region and verified using an unsupervised machine learning approach. The resulting sample of periodic LINEAR variables is dominated by 3900 RR Lyrae stars and 2700 eclipsing binary stars of all subtypes and includes small fractions of relatively rare populations such as asymptotic giant branch stars and SX Phoenicis stars. We discuss the distribution of these mostly uncataloged variables in various diagrams constructed with optical-to-infrared SDSS, Two Micron All Sky Survey, and Wide-field Infrared Survey Explorer photometry, and with LINEAR light-curve features. We find that the combination of light-curve features and colors enables classification schemes much more powerful than when colors or light curves are each used separately. An interesting side result is a robust and precise quantitative description of a strong correlation between the light-curve period and color/spectral type for close and contact eclipsing binary stars (β Lyrae and W UMa): as the color-based spectral type varies from K4 to F5, the

Modelling secondary eclipses of Kepler exoplanets

Directory of Open Access Journals (Sweden)

Hambálek Lubomír

2015-01-01

Full Text Available We have selected several Kepler objects with potentially the deepest secondary eclipses. By combination of many single phased light-curves (LCs we have produced a smooth LC with a larger SNR and made the secondary eclipses more distinct. This allowed us to measure the depth of primary and secondary minimum with greater accuracy and then to determine stellar and planetary radii by simplex modelling.

Gaia eclipsing binary and multiple systems. Supervised classification and self-organizing maps

Science.gov (United States)

Süveges, M.; Barblan, F.; Lecoeur-Taïbi, I.; Prša, A.; Holl, B.; Eyer, L.; Kochoska, A.; Mowlavi, N.; Rimoldini, L.

2017-07-01

Context. Large surveys producing tera- and petabyte-scale databases require machine-learning and knowledge discovery methods to deal with the overwhelming quantity of data and the difficulties of extracting concise, meaningful information with reliable assessment of its uncertainty. This study investigates the potential of a few machine-learning methods for the automated analysis of eclipsing binaries in the data of such surveys. Aims: We aim to aid the extraction of samples of eclipsing binaries from such databases and to provide basic information about the objects. We intend to estimate class labels according to two different, well-known classification systems, one based on the light curve morphology (EA/EB/EW classes) and the other based on the physical characteristics of the binary system (system morphology classes; detached through overcontact systems). Furthermore, we explore low-dimensional surfaces along which the light curves of eclipsing binaries are concentrated, and consider their use in the characterization of the binary systems and in the exploration of biases of the full unknown Gaia data with respect to the training sets. Methods: We have explored the performance of principal component analysis (PCA), linear discriminant analysis (LDA), Random Forest classification and self-organizing maps (SOM) for the above aims. We pre-processed the photometric time series by combining a double Gaussian profile fit and a constrained smoothing spline, in order to de-noise and interpolate the observed light curves. We achieved further denoising, and selected the most important variability elements from the light curves using PCA. Supervised classification was performed using Random Forest and LDA based on the PC decomposition, while SOM gives a continuous 2-dimensional manifold of the light curves arranged by a few important features. We estimated the uncertainty of the supervised methods due to the specific finite training set using ensembles of models constructed

Study of the eclipses of cataclysmic variables

International Nuclear Information System (INIS)

Zhang, E.H.

1986-01-01

The cataclysmic variables (CV's) are all close binary stars in which a secondary star fills its Roche lobe and transfers mass to its white dwarf companion. The transferred mass forms an accretion disk or ring, around the white dwarf. Reliable determinations of the masses of the two-component stars, the distributions of temperature and brightness across the disk, and other parameters, are necessary to understand both the CV's and the accretion processes, but they are extremely difficult to measure. The best way to obtain this data is to observe eclipsing CV's. The author developed a computer program to synthesize light curves of eclipsing CV's using the most realistic model built so far to analyze the eclipses of CV's. A statistical method was developed to perform a complete error analysis of the results of the numerical studies. High-speed, multi-color photometry of three eclipsing CV's - HT Cas, U Gem, and AC Cnc - was obtained. Using the program to analyze the observed light curves, the author derived, for each system, the orbital inclination, the sizes, masses and temperature of the two component stars, and the temperature distribution across the disk

The eclipsing system V404 Lyr: Light-travel times and γ Doradus pulsations

Energy Technology Data Exchange (ETDEWEB)

Lee, Jae Woo; Kim, Seung-Lee; Hong, Kyeongsoo; Lee, Chung-Uk; Koo, Jae-Rim, E-mail: jwlee@kasi.re.kr, E-mail: slkim@kasi.re.kr, E-mail: kshong@kasi.re.kr, E-mail: leecu@kasi.re.kr, E-mail: koojr@kasi.re.kr [Korea Astronomy and Space Science Institute, Daejeon 305-348 (Korea, Republic of)

2014-08-01

We present the physical properties of V404 Lyr exhibiting eclipse timing variations and multiperiodic pulsations from all historical data including the Kepler and SuperWASP observations. Detailed analyses of 2922 minimum epochs showed that the orbital period has varied through a combination of an upward-opening parabola and two sinusoidal variations, with periods of P {sub 3} = 649 days and P {sub 4} = 2154 days and semi-amplitudes of K {sub 3} = 193 s and K {sub 4} = 49 s, respectively. The secular period increase at a rate of +1.41 × 10{sup –7} days yr{sup –1} could be interpreted as a combination of the secondary to primary mass transfer and angular momentum loss. The most reasonable explanation for both sinusoids is a pair of light-travel-time effects due to two circumbinary objects with projected masses of M {sub 3} = 0.47 M {sub ☉} and M {sub 4} = 0.047 M {sub ☉}. The third-body parameters are consistent with those calculated using the Wilson-Devinney binary code. For the orbital inclinations i {sub 4} ≳ 43°, the fourth component has a mass within the hydrogen-burning limit of ∼0.07 M {sub ☉}, which implies that it is a brown dwarf. A satisfactory model for the Kepler light curves was obtained by applying a cool spot to the secondary component. The results demonstrate that the close eclipsing pair is in a semi-detached, but near-contact, configuration; the primary fills approximately 93% of its limiting lobe and is larger than the lobe-filling secondary. Multiple frequency analyses were applied to the light residuals after subtracting the synthetic eclipsing curve from the Kepler data. This revealed that the primary component of V404 Lyr is a γ Dor type pulsating star, exhibiting seven pulsation frequencies in the range of 1.85-2.11 day{sup –1} with amplitudes of 1.38-5.72 mmag and pulsation constants of 0.24-0.27 days. The seven frequencies were clearly identified as high-order low-degree gravity-mode oscillations which might be excited

B and V photometry and analysis of the eclipsing binary RZ CAS

Science.gov (United States)

Riazi, N.; Bagheri, M. R.; Faghihi, F.

1994-01-01

Photoelectric light curves of the eclipsing binary RZ Cas are presented for B and V filters. The light curves are analyzed for light and geometrical elements, starting with a previously suggested preliminary method. The approximate results thus obtained are then optimised through the Wilson-Devinney computer programs.

Physics of Eclipsing Binaries: Modelling in the new era of ultra-high precision photometry

OpenAIRE

Pavlovski, K.; Bloemen, S.; Degroote, P.; Conroy, K.; Hambleton, Kelly; Giammarco, J.M.; Pablo, H.; Prša, A.; Tkachenko, A.; Torres, G.

2013-01-01

Recent ultra-high precision observations of eclipsing binaries, especially data acquired by the Kepler satellite, have made accurate light curve modelling increasingly challenging but also more rewarding. In this contribution, we discuss low-amplitude signals in light curves that can now be used to derive physical information about eclipsing binaries but that were unaccessible before the Kepler era. A notable example is the detection of Doppler beaming, which leads to an increase in flux when...

Preliminary study of light variations of the eclipsing binary AB Cassiopeiae

International Nuclear Information System (INIS)

Ando, H.; Manchester Univ.

1980-01-01

Preliminary study of the eclipsing binary AB Cas is presented here by using the photometric observational data. The primary component is one of the delta Sct variables with period of 0.sup(d)054, and whether the oscillation is of a radial mode or of a non-radial one is discussed. Two colour indices (B - V and U - B) data and the light curve analysis suggest that this binary system is a typical Algol type binary system, in which the primary component is near the ZAMS with about 2.3 Msub(sun) and the secondary one is a subgiant star with about 0.5 Msub(sun). (orig.)

Statistical eclipses of close-in Kepler sub-Saturns

Energy Technology Data Exchange (ETDEWEB)

Sheets, Holly A.; Deming, Drake, E-mail: hsheets@astro.umd.edu [Department of Astronomy, University of Maryland, College Park, MD 20742-2421 (United States)

2014-10-20

We present a method to detect small atmospheric signals in Kepler's planet candidate light curves by averaging light curves for multiple candidates with similar orbital and physical characteristics. Our statistical method allows us to measure unbiased physical properties of Kepler's planet candidates, even for candidates whose individual signal-to-noise precludes the detection of their secondary eclipse. We detect a secondary eclipse depth of 3.83{sub −1.11}{sup +1.10} ppm for a group of 31 sub-Saturn (R < 6 R {sub ⊕}) planet candidates with the greatest potential for a reflected light signature ((R{sub p} /a){sup 2} > 10 ppm). Including Kepler-10b in this group increases the depth to 5.08{sub −0.72}{sup +0.71} ppm. For a control group with (R{sub p} /a){sup 2} < 1 ppm, we find a depth of 0.36 ± 0.37 ppm, consistent with no detection. We also analyze the light curve of Kepler-10b and find an eclipse depth of 7.08 ± 1.06 ppm. If the eclipses are due solely to reflected light, this corresponds to a geometric albedo of 0.22 ± 0.06 for our group of close-in sub-Saturns, 0.37 ± 0.05 if including Kepler-10b in the group, and 0.60 ± 0.09 for Kepler-10b alone. Including a thermal emission model does not change the geometric albedo appreciably, assuming A{sub B} = (3/2)*A{sub g} . Our result for Kepler-10b is consistent with previous works. Our result for close-in sub-Saturns shows that Kepler-10b is unusually reflective, but our analysis is consistent with the results of Demory for super-Earths. Our results also indicate that hot Neptunes are typically more reflective than hot Jupiters.

TIDALLY INDUCED PULSATIONS IN KEPLER ECLIPSING BINARY KIC 3230227

Energy Technology Data Exchange (ETDEWEB)

Guo, Zhao; Gies, Douglas R. [Center for High Angular Resolution Astronomy and Department of Physics and Astronomy, Georgia State University, P.O. Box 5060, Atlanta, GA 30302-5060 (United States); Fuller, Jim, E-mail: guo@astro.gsu.edu, E-mail: gies@chara.gsu.edu, E-mail: jfuller@caltech.edu [TAPIR, Walter Burke Institute for Theoretical Physics, Mailcode 350-17, Caltech, Pasadena, CA 91125 (United States)

2017-01-01

KIC 3230227 is a short period (P  ≈ 7.0 days) eclipsing binary with a very eccentric orbit ( e  = 0.6). From combined analysis of radial velocities and Kepler light curves, this system is found to be composed of two A-type stars, with masses of M {sub 1} = 1.84 ± 0.18  M {sub ⊙}, M {sub 2} = 1.73 ± 0.17  M {sub ⊙} and radii of R {sub 1} = 2.01 ± 0.09  R {sub ⊙}, R {sub 2} = 1.68 ± 0.08 R {sub ⊙} for the primary and secondary, respectively. In addition to an eclipse, the binary light curve shows a brightening and dimming near periastron, making this a somewhat rare eclipsing heartbeat star system. After removing the binary light curve model, more than 10 pulsational frequencies are present in the Fourier spectrum of the residuals, and most of them are integer multiples of the orbital frequency. These pulsations are tidally driven, and both the amplitudes and phases are in agreement with predictions from linear tidal theory for l  = 2, m  = −2 prograde modes.

TIDALLY INDUCED PULSATIONS IN KEPLER ECLIPSING BINARY KIC 3230227

International Nuclear Information System (INIS)

Guo, Zhao; Gies, Douglas R.; Fuller, Jim

2017-01-01

KIC 3230227 is a short period (P  ≈ 7.0 days) eclipsing binary with a very eccentric orbit ( e  = 0.6). From combined analysis of radial velocities and Kepler light curves, this system is found to be composed of two A-type stars, with masses of M 1  = 1.84 ± 0.18  M ⊙ , M 2  = 1.73 ± 0.17  M ⊙ and radii of R 1  = 2.01 ± 0.09  R ⊙ , R 2  = 1.68 ± 0.08 R ⊙ for the primary and secondary, respectively. In addition to an eclipse, the binary light curve shows a brightening and dimming near periastron, making this a somewhat rare eclipsing heartbeat star system. After removing the binary light curve model, more than 10 pulsational frequencies are present in the Fourier spectrum of the residuals, and most of them are integer multiples of the orbital frequency. These pulsations are tidally driven, and both the amplitudes and phases are in agreement with predictions from linear tidal theory for l  = 2, m  = −2 prograde modes.

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

Science.gov (United States)

Zendejas Dominguez, Jesus

2013-12-01

-fitting algorithm. The implementation on the detection algorithm performs a trapezoid-fit to the folded light curve. We show that the new fit is able to produce more accurate results than the box-fit model. We describe a set of selection criteria to search for transit candidates that include a parameter calculated by our detection algorithm: the V-shape parameter, which has proven to be useful to automatically identify and remove eclipsing binaries from the survey. The criteria are optimized using Monte-Carlo simulations of artificial transit signals that are injected into the real WTS light curves and subsequently analyzed by our detection algorithm. We separately optimize the selection criteria for two different sets of light curves, one for F-G-K stars, and another for M-dwarfs. In order to search for transiting planet candidates, the optimized selection criteria are applied to the aperture photometry and difference imaging light curves. In this way, the best 200 transit candidates from a sample of ~ 475 000 sources are automatically selected. A visual inspection of the folded light curves of these detections is carried out to eliminate clear false-positives or false-detections. Subsequently, several analysis steps are performed on the 18 best detections, which allow us to classify these objects as transiting planet and eclipsing binary candidates. We report one planet candidate orbiting a late G-type star, which is proposed for photometric follow-up. The independent analysis on the M-dwarf sample provides no planet candidates around these stars. Therefore, the null detection hypothesis and upper limits on the occurrence rate of giant planets around M-dwarfs with J detections around M stars indicates that it is not necessary to invoke the disk instability formation mechanism, coupled with an orbital migration process to explain the presence of such planets around low-mass stars. The much reduced efficiency of the core-accretion model to form Jupiters around cool stars seems to

UBV Light Curves of AR Lacertae During 1980-'81 and 1981-'82

Directory of Open Access Journals (Sweden)

Il-Seong Nha

1985-12-01

Full Text Available The UBV observations of the brightest RE CVn-type eclipsing binary star AR Lac were made at four observatories, two in Korea and two in the U.S. in the 1980-81 and 1981-82 seasons. As a result of the cooperation, two light curves in the yellow and in the blue were completed for each observing seasons. Ultraviolet observations were also made at three of the four observatories. The orbital period of AR Lac apparantly decreased around 1977. An analysis of our yellow light curves together with five other yellow curves available in the literature since 1975 shows that there seems no periodicity in the migration of the distortion waves. There is a gradual decrease of at least 0.m1 between 1976 and 1982 in the brightness of the cooler component if one assumes that the hotter component is constant.

The fidelity of Kepler eclipsing binary parameters inferred by the neural network

Science.gov (United States)

Holanda, N.; da Silva, J. R. P.

2018-04-01

This work aims to test the fidelity and efficiency of obtaining automatic orbital elements of eclipsing binary systems, from light curves using neural network models. We selected a random sample with 78 systems, from over 1400 eclipsing binary detached obtained from the Kepler Eclipsing Binaries Catalog, processed using the neural network approach. The orbital parameters of the sample systems were measured applying the traditional method of light curve adjustment with uncertainties calculated by the bootstrap method, employing the JKTEBOP code. These estimated parameters were compared with those obtained by the neural network approach for the same systems. The results reveal a good agreement between techniques for the sum of the fractional radii and moderate agreement for e cos ω and e sin ω, but orbital inclination is clearly underestimated in neural network tests.

The Wolf-Rayet eclipsing binary HD 5980 in the Small Magellanic Cloud

International Nuclear Information System (INIS)

Breysacher, J.; Moffat, A.F.J.

1982-01-01

The Wolf-Rayet star HD 5980, which is probably associated with the bright HII region NGC 346 of the Small Magellanic Cloud, was found to be an eclipsing binary by Hoffmann, Stift and Moffat (1978). Breysacher and Perrier (1980) determined the orbital period, P=19.26 +- 0.003d, of the system whose light curve reveals a strongly eccentric orbit (e=0.47 for i=80 0 ). The behaviour of the light curve outside the eclipses shows that one is dealing with a rather complex binary system. An analysis of the spectroscopic data is presented here. (Auth.)

Hot spot in eclipsing dwarf nova IY Ursae Majoris during quiescence and normal outburst

OpenAIRE

Bakowska, K.; Olech, A.

2016-01-01

We present the analysis of hot spot brightness in light curves of the eclipsing dwarf nova IY Ursae Majoris during its normal outburst in March 2013 and in quiescence in April 2012 and in October 2015. Examination of four reconstructed light curves of the hot spot eclipses showed directly that the brightness of the hot spot changed significantly only during the outburst. The brightness of the hot spot, before and after the outburst, was on the same level. Hereby, based on the behaviour of the...

THE ECLIPSING SYSTEM EP ANDROMEDAE AND ITS CIRCUMBINARY COMPANIONS

Energy Technology Data Exchange (ETDEWEB)

Lee, Jae Woo; Hinse, Tobias Cornelius; Park, Jang-Ho, E-mail: jwlee@kasi.re.kr, E-mail: tchinse@gmail.com, E-mail: pooh107162@kasi.re.kr [Korea Astronomy and Space Science Institute, Daejeon 305-348 (Korea, Republic of)

2013-04-15

We present new long-term CCD photometry for EP And acquired during the period 2007-2012. The light curves display total eclipses at primary minima and season-to-season light variability. Our synthesis for all available light curves indicates that the eclipsing pair is a W-type overcontact binary with parameters of q = 2.578, i = 83. Degree-Sign 3, {Delta}T = 27 K, f = 28%, and l{sub 3} = 2%-3%. The asymmetric light curves in 2007 were satisfactorily modeled by a cool spot on either of the eclipsing components from a magnetic dynamo. Including our 95 timing measurements, a total of 414 times of minimum light spanning about 82 yr was used for a period study. A detailed analysis of the eclipse timing diagram revealed that the orbital period of EP And has varied as a combination of an upward-opening parabola and two periodic variations, with cycle lengths of P{sub 3} = 44.6 yr and P{sub 4} = 1.834 yr and semi-amplitudes of K{sub 3} = 0.0100 days and K{sub 4} = 0.0039 days, respectively. The observed period increase at a fractional rate of +1.39 Multiplication-Sign 10{sup -10} is in excellent agreement with that calculated from the W-D code and can be plausibly explained by some combination of mass transfer from the primary to the secondary star and angular momentum loss due to magnetic braking. The most reasonable explanation for both cycles is a pair of light-travel-time effects driven by the possible existence of a third and fourth component with projected masses of M{sub 3} = 0.25 M{sub Sun} and M{sub 4} = 0.90 M{sub Sun }. The more massive companion could be revealed using high-resolution spectroscopic data extending over the course of a few years and could also be a binary itself. It is possible that the circumbinary objects may have played an important role in the formation and evolution of the eclipsing pair, which would cause it to have a short initial orbital period and thus evolve into an overcontact configuration by angular momentum loss.

Infrared observations of the eclipsing millisecond pulsar 1957 + 20

International Nuclear Information System (INIS)

Eales, S.A.; Becklin, E.E.; Zuckerman, B.

1990-01-01

We have taken 2.2-μm images, over the entire range of orbital phase, of the eclipsing millisecond pulsar 1957 + 20. We show that the 2.2-μm flux from the pulsar system is variable, and that the infrared light curve is similar to the optical light curve. Four additional images at 1.2 μm show that there is a possible infrared excess from the system. (author)

EXPECTED LARGE SYNOPTIC SURVEY TELESCOPE (LSST) YIELD OF ECLIPSING BINARY STARS

International Nuclear Information System (INIS)

Prsa, Andrej; Pepper, Joshua; Stassun, Keivan G.

2011-01-01

In this paper, we estimate the Large Synoptic Survey Telescope (LSST) yield of eclipsing binary stars, which will survey ∼20,000 deg 2 of the southern sky during a period of 10 years in six photometric passbands to r ∼ 24.5. We generate a set of 10,000 eclipsing binary light curves sampled to the LSST time cadence across the whole sky, with added noise as a function of apparent magnitude. This set is passed to the analysis-of-variance period finder to assess the recoverability rate for the periods, and the successfully phased light curves are passed to the artificial-intelligence-based pipeline ebai to assess the recoverability rate in terms of the eclipsing binaries' physical and geometric parameters. We find that, out of ∼24 million eclipsing binaries observed by LSST with a signal-to-noise ratio >10 in mission lifetime, ∼28% or 6.7 million can be fully characterized by the pipeline. Of those, ∼25% or 1.7 million will be double-lined binaries, a true treasure trove for stellar astrophysics.

REFLECTED LIGHT CURVES, SPHERICAL AND BOND ALBEDOS OF JUPITER- AND SATURN-LIKE EXOPLANETS

Energy Technology Data Exchange (ETDEWEB)

Dyudina, Ulyana; Kopparla, Pushkar; Ingersoll, Andrew P.; Yung, Yuk L. [Division of Geological and Planetary Sciences, 150-21 California Institute of Technology, Pasadena, CA 91125 (United States); Zhang, Xi [University of California Santa Cruz 1156 High Street, Santa Cruz, CA 95064 (United States); Li, Liming [Department of Physics, University of Houston, Houston, TX 77204 (United States); Dones, Luke [Southwest Research Institute, 1050 Walnut Street, Suite 300, Boulder CO 80302 (United States); Verbiscer, Anne, E-mail: ulyana@gps.caltech.edu [Department of Astronomy, University of Virginia, Charlottesville, VA 22904-4325 (United States)

2016-05-10

Reflected light curves observed for exoplanets indicate that a few of them host bright clouds. We estimate how the light curve and total stellar heating of a planet depends on forward and backward scattering in the clouds based on Pioneer and Cassini spacecraft images of Jupiter and Saturn. We fit analytical functions to the local reflected brightnesses of Jupiter and Saturn depending on the planet’s phase. These observations cover broadbands at 0.59–0.72 and 0.39–0.5 μ m, and narrowbands at 0.938 (atmospheric window), 0.889 (CH4 absorption band), and 0.24–0.28 μ m. We simulate the images of the planets with a ray-tracing model, and disk-integrate them to produce the full-orbit light curves. For Jupiter, we also fit the modeled light curves to the observed full-disk brightness. We derive spherical albedos for Jupiter and Saturn, and for planets with Lambertian and Rayleigh-scattering atmospheres. Jupiter-like atmospheres can produce light curves that are a factor of two fainter at half-phase than the Lambertian planet, given the same geometric albedo at transit. The spherical albedo is typically lower than for a Lambertian planet by up to a factor of ∼1.5. The Lambertian assumption will underestimate the absorption of the stellar light and the equilibrium temperature of the planetary atmosphere. We also compare our light curves with the light curves of solid bodies: the moons Enceladus and Callisto. Their strong backscattering peak within a few degrees of opposition (secondary eclipse) can lead to an even stronger underestimate of the stellar heating.

A visible and infrared study of the eclipsing dwarf nova Oy Carinae

International Nuclear Information System (INIS)

Berriman, G.

1984-01-01

This paper presents three simultaneous visible (V) and infrared (J,H,K) light curves of the eclipsing dwarf nova binary system OY Carinae in quiescence. The infrared light curves show a secondary minimum, not seen in the visible, which is the ellipsoidal variations of the red dwarf and its eclipse by the accretion disc surrounding the white dwarf companion. The red star, an M dwarf, supplies between 30 and 60 per cent of the total light at J,H and K. This requires that the system is between 100 and 300 pc away. The infrared continuum of the accretion disc around the white dwarf companion comes largely from the optically thin gas giving rise to the emission lines seen in the visible and ultraviolet. (author)

The Kepler eclipsing system KIC 5621294 and its substellar companion

Energy Technology Data Exchange (ETDEWEB)

Lee, Jae Woo; Hong, Kyeongsoo; Hinse, Tobias Cornelius, E-mail: jwlee@kasi.re.kr, E-mail: kshong@kasi.re.kr, E-mail: tchinse@gmail.com [Korea Astronomy and Space Science Institute, Daejeon 305-348 (Korea, Republic of)

2015-03-01

We present the physical properties of KIC 5621294, showing light and timing variations from the Kepler photometry. Its light curve displays partial eclipses and the O’Connell effect, with Max II fainter than Max I, which was fitted quite well by applying third-body and spot effects to the system. The results indicate that the eclipsing pair is a classical Algol-type system with parameters of q = 0.22, i = 76.°8, and Δ(T{sub 1}−T{sub 2}) = 4235 K, in which the detached primary component fills about 77% of its limiting lobe. Striking discrepancies exist between the primary and secondary eclipse times obtained with the method of Kwee and van Woerden. These are mainly caused by surface inhomogeneities due to spot activity detected in our light curve synthesis. The 1253 light curve timings from the Wilson–Devinney code were used for a period study. It was found that the orbital period of KIC 5621294 has varied due to periodic variation overlaid on a downward parabola. The sinusoidal variation with a period of 961 days and a semi-amplitude of 22.5 s most likely arises from a light-time effect due to a third component with a mass of M{sub 3}sini{sub 3} = 46.9 M{sub Jup}, which is in good agreement with that calculated from the light curve itself. If its orbital inclination is larger than about 40°, the mass of the circumbinary object would possibly match a brown dwarf. The parabolic variation could not be fully explained by either a mass transfer between the binary components or angular momentum via magnetic braking. It is possible that the parabola may be the only observed part of a period modulation caused by the presence of another companion in a wider orbit.

UBV Light Curves of ζ AUR Star 32 Cygni

Directory of Open Access Journals (Sweden)

Il-Seong Nha

1992-12-01

Full Text Available UBV ovservation of ζ Aur star 32 Cyg have been at the Yonsei University Observatory suing the 60-cm Goto reflector and five years, 1988-1992. Observations made during these years cover outside of eclipse phase only. No significant light variation which would represent the secondary eclipse of red supergiant by a hot main sequence star is found. The light levels in three passbands do not show any evidence of the proximate effect of this binary system. Some strong light variations, particularly in U, are discussed with no successful explanation.

A visible and infrared study of the eclipsing dwarf nova OY Carinae

International Nuclear Information System (INIS)

Berriman, G.

1984-01-01

This paper presents four visible light curves of the highly inclined, short-period cataclysmic binary star OY Carinae in quiescence. These light curves show that the red dwarf eclipses both its white dwarf companion and the accretion disc and hotspot, which originate from material transferred from the red dwarf to the white dwarf. The consequences of the findings are discussed in the light of current ideas about the evolution of cataclysmic variable stars. (author)

St. Benedict Sees the Light: Asam's Solar Eclipses as Metaphor

Science.gov (United States)

Olson, Roberta J. M.; Pasachoff, Jay M.

During the Baroque period, artists worked in a style - encouraged by the Roman Catholic Church and the Council of Trent - that revealed the divine in natural forms and made religious experiences more accessible. Cosmas Damian Asam, painter and architect, and his brother Egid (Aegid) Quirin Asam, sculptor and stuccatore, were the principal exponents of eighteenth-century, southern-German religious decoration and architecture in the grand manner, the Gesamtkunstwerk. Cosmas Damian's visionary and ecstatic art utilized light, both physical and illusionistic, together with images of meteorological and astronomical phenomena, such as solar and lunar eclipses. This paper focuses on his representations of eclipses and demonstrates how Asam was galvanized by their visual, as well as metaphorical power and that he studied a number of them. He subsequently applied his observations in a series of paintings for the Benedictine order that become increasingly astronomically accurate and spiritually profound. From the evidence presented, especially in three depictions of St. Benedict's vision, the artist harnessed his observations to visualize the literary description of the miraculous event in the Dialogues of St. Gregory the Great, traditionally a difficult scene to illustrate, even for Albrecht Dürer. Asam painted the trio at Einsiedeln, Switzerland (1724-27); Kladruby, the Czech Republic (1725-27), where he captured the solar corona and the "diamond-ring effect"; and Weltenburg, Germany (1735), where he also depicted the diamond-ring effect at a total solar eclipse. We conclude that his visualizations were informed by his personal observations of the solar eclipses on 12 May 1706, 22 May 1724, and 13 May 1733. Asam may have also known the eclipse maps of Edmond Halley and William Whiston that were issued in advance. Astronomers did not start studying eclipses scientifically until the nineteenth century, making Asam's depictions all the more fascinating. So powerful was the

KMTNet Time-series Photometry of the Doubly Eclipsing Binary Stars Located in the Large Magellanic Cloud

Science.gov (United States)

Hong, Kyeongsoo; Koo, Jae-Rim; Lee, Jae Woo; Kim, Seung-Lee; Lee, Chung-Uk; Park, Jang-Ho; Kim, Hyoun-Woo; Lee, Dong-Joo; Kim, Dong-Jin; Han, Cheongho

2018-05-01

We report the results of photometric observations for doubly eclipsing binaries OGLE-LMC-ECL-15674 and OGLE-LMC-ECL-22159, both of which are composed of two pairs (designated A&B) of a detached eclipsing binary located in the Large Magellanic Cloud. The light curves were obtained by high-cadence time-series photometry using the Korea Microlensing Telescope Network 1.6 m telescopes located at three southern sites (CTIO, SAAO, and SSO) between 2016 September and 2017 January. The orbital periods were determined to be 1.433 and 1.387 days for components A and B of OGLE-LMC-ECL-15674, respectively, and 2.988 and 3.408 days for OGLE-LMC-ECL-22159A and B, respectively. Our light curve solutions indicate that the significant changes in the eclipse depths of OGLE-LMC-ECL-15674A and B were caused by variations in their inclination angles. The eclipse timing diagrams of the A and B components of OGLE-LMC-ECL-15674 and OGLE-LMC-ECL-22159 were analyzed using 28, 44, 28, and 26 new times of minimum light, respectively. The apsidal motion period of OGLE-LMC-ECL-15674B was estimated by detailed analysis of eclipse timings for the first time. The detached eclipsing binary OGLE-LMC-ECL-15674B shows a fast apsidal period of 21.5 ± 0.1 years.

Investigations of a New Eclipsing Cataclysmic Variable HBHA 4705-03

Science.gov (United States)

Yakin, D. G.; Suleimanov, V. F.; Shimansky, V. V.; Vlasyuk, V. V.; Spiridonova, O. I.

2013-01-01

Results of photometric and spectroscopic investigations of the recently discovered eclipsing cataclysmic variable star HBHA 4705-03 are presented. The emission spectra of the system show broad hydrogen and helium emission lines. The bright spots with an approximately zero velocity components are found in the Doppler maps for the hydrogen and ionized helium lines. The disc structure is more prominent in the maps for the neutral helium lines. The masses of the components (MWD = 0.54 ± 0.10M⊙ and MRD = 0.45 ± 0.05 M⊙), and the orbit inclination (i = 71.°8 ± 0.°7) were estimated using the radial velocity light curve and the eclipse width. The modeling of the light curve allows us to evaluate the bright spot parameters and the mass accretion rate (M ≍ 2 ·1017 g s-1).

New BV light curves of the eclipsing binary 44i Bootis

International Nuclear Information System (INIS)

Rovithis, P.; Rovithis-Livaniou, H.

1990-01-01

The eclipsing binary 44i Bootis, the fainter component of the visual binary ADS 9494, has been observed during 1980 as well as during 1988. The observations were made with the 48-inch Cassegrain reflector at the Kryonerion Station of the National Observatory of Athens, Greece. The individual observations of 44i Bootis are presented for years 1980 and 1988 and are also discussed. A linear as well as a quadratic least square fitting to the O-C diagram of 44i Boo for the last decade is given in which it is shown that the period of the system continues to increase

Eclipses of cataclysmic variables. II. U Geminorum

International Nuclear Information System (INIS)

Zhang, E.H.; Robinson, E.L.

1987-01-01

U Gem is an eclipsing dwarf nova with an orbital period of 4 h 15 m. High-speed, multicolor photometric observations of U Gem in its quiescent state were obtained. A program was used that synthesizes the light curves of cataclysmic variables to derive the properties of U Gem from its eclipses. Using radial velocity curves published by Wade (1981) and by Stover (1981), it was found that i = 69.7 + or - 0.7 deg, M1 = 1.12 + or - 0.13 solar masses, and M2 = 0.53 + or - 0.06 solar mass. The radial temperature distribution across the accretion disk in U Gem shows that the disk is a hollow ring around the white dwarf with R(out) = 0.30 + or - 0.04 and R(in) = 0.12 + or - 0.05 a, where a is the separation of the two stars. The temperature of the ring is 4800 + or - 300 K. The model also reproduces the published infrared light curves and ultraviolet spectral distributions of U Gem. A mass transfer rate of 7.8 x 10 to the -10th solar mass/yr is derived. The structure of the ring around the white dwarf is consistent with the current theories of accretion disk instabilities in dwarf novae. 39 references

Observations and light curve solutions of four ultrashort-period binaries

Directory of Open Access Journals (Sweden)

Kjurkchieva D.

2016-01-01

Full Text Available The paper presents light curve solutions of our observations of four new ultrashort-period eclipsing binaries with MS components. Two of them have periods almost at the upper limit (0.22 days of the ultrashort-period binaries, while the periods of around 0.18 days of CSS J171508.5+350658 and CSS J214633.8+120016 are amongst the shortest known orbital periods. CSS J171410.0+ 445850, CSS J214633.8+120016 and CSS J224326.0+154532 are over contact binaries with fill out factors around 0.25 while CSS J171508.5+350658 is a semidetached system. The two targets with shortest periods consist of M dwarfs.

A DEEPLY ECLIPSING DETACHED DOUBLE HELIUM WHITE DWARF BINARY

International Nuclear Information System (INIS)

Parsons, S. G.; Marsh, T. R.; Gaensicke, B. T.; Drake, A. J.; Koester, D.

2011-01-01

Using Liverpool Telescope+RISE photometry we identify the 2.78 hr period binary star CSS 41177 as a detached eclipsing double white dwarf binary with a 21,100 K primary star and a 10,500 K secondary star. This makes CSS 41177 only the second known eclipsing double white dwarf binary after NLTT 11748. The 2 minute long primary eclipse is 40% deep and the secondary eclipse 10% deep. From Gemini+GMOS spectroscopy, we measure the radial velocities of both components of the binary from the Hα absorption line cores. These measurements, combined with the light curve information, yield white dwarf masses of M 1 = 0.283 ± 0.064 M sun and M 2 = 0.274 ± 0.034 M sun , making them both helium core white dwarfs. As an eclipsing, double-lined spectroscopic binary, CSS 41177 is ideally suited to measuring precise, model-independent masses and radii. The two white dwarfs will merge in roughly 1.1 Gyr to form a single sdB star.

BEER ANALYSIS OF KEPLER AND CoRoT LIGHT CURVES. IV. DISCOVERY OF FOUR NEW LOW-MASS WHITE DWARF COMPANIONS IN THE KEPLER DATA

Energy Technology Data Exchange (ETDEWEB)

Faigler, S.; Kull, I.; Mazeh, T.; Kiefer, F. [School of Physics and Astronomy, Raymond and Beverly Sackler Faculty of Exact Sciences, Tel Aviv University, Tel Aviv 69978 (Israel); Latham, D. W. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Bloemen, S. [Department of Astrophysics, IMAPP, Radboud University Nijmegen, P.O. BOX 9010, NL-6500 GL Nijmegen (Netherlands)

2015-12-10

We report the discovery of four short-period eclipsing systems in the Kepler light curves, consisting of an A-star primary and a low-mass white dwarf (WD) secondary (dA+WD)—KIC 4169521, KOI-3818, KIC 2851474, and KIC 9285587. The systems show BEaming, Ellipsoidal and Reflection (BEER) phase modulations together with primary and secondary eclipses. These add to the 6 Kepler and 18 WASP short-period eclipsing dA+WD binaries that were previously known. The light curves, together with follow-up spectroscopic observations, allow us to derive the masses, radii, and effective temperatures of the two components of the four systems. The orbital periods, of 1.17–3.82 days, and WD masses, of 0.19–0.22 M{sub ⊙}, are similar to those of the previously known systems. The WD radii of KOI-3818, KIC 2851474, and KIC 9285587 are 0.026, 0.035, and 0.026 R{sub ⊙}, respectively, the smallest WD radii derived so far for short-period eclipsing dA+WD binaries. These three binaries extend the previously known population to older systems with cooler and smaller WD secondaries. KOI-3818 displays evidence for a fast-rotating primary and a minute but significant eccentricity, ∼1.5 × 10{sup −3}. These features are probably the outcome of the mass-transfer process.

Period Study and Analyses of 2017 Observations of the Totally Eclipsing, Solar Type Binary, MT Camelopardalis

Science.gov (United States)

Faulkner, Danny R.; Samec, Ronald G.; Caton, Daniel B.

2018-06-01

We report here on a period study and the analysis of BVRcIc light curves (taken in 2017) of MT Cam (GSC03737-01085), which is a solar type (T ~ 5500K) eclipsing binary. D. Caton observed MT Cam on 05, 14, 15, 16, and 17, December 2017 with the 0.81-m reflector at Dark Sky Observatory. Six times of minimum light were calculated from four primary eclipses and two secondary eclipses:HJD I = 24 58092.4937±0.0002, 2458102.74600±0.0021, 2458104.5769±0.0002, 2458104.9434±0.0029HJD II = 2458103.6610±0.0001, 2458104.7607±0.0020,Six times of minimum light were also calculated from data taken by Terrell, Gross, and Cooney, in their 2016 and 2004 observations (reported in IBVS #6166; TGC, hereafter). In addition, six more times of minimum light were taken from the literature. From all 18 times of minimum light, we determined the following light elements:JD Hel Min I=2458102.7460(4) + 0.36613937(5) EWe found the orbital period was constant over the 14 years spanning all observations. We note that TGC found a slightly increasing period. However, our results were obtained from a period study rather than comparison of observations from only two epochs by the Wilson-Devinney (W-D) Program. A BVRcIc Johnson-Cousins filtered simultaneous W-D Program solution gives a mass ratio (0.3385±0.0014) very nearly the same as TGC’s (0.347±0.003), and a component temperature difference of only ~40 K. As with TGC, no spot was needed in the modeling. Our modeling (beginning with Binary Maker 3.0 fits) was done without prior knowledge of TGC’s. This shows the agreement achieved when independent analyses are done with the W-D code. The present observations were taken 1.8 years later than the last curves by TGC, so some variation is expected.The Roche Lobe fill-out of the binary is ~13% and the inclination is ~83.5 degrees. The system is a shallow contact W-type W UMa Binary, albeit, the amplitudes of the primary and secondary eclipse are very nearly identical. An eclipse duration of ~21

Artificial Intelligence Approach to the Determination of Physical Properties of Eclipsing Binaries. I. The EBAI Project

Science.gov (United States)

Prša, A.; Guinan, E. F.; Devinney, E. J.; DeGeorge, M.; Bradstreet, D. H.; Giammarco, J. M.; Alcock, C. R.; Engle, S. G.

2008-11-01

Achieving maximum scientific results from the overwhelming volume of astronomical data to be acquired over the next few decades demands novel, fully automatic methods of data analysis. Here we concentrate on eclipsing binary (EB) stars, a prime source of astrophysical information, of which only some hundreds have been rigorously analyzed, but whose numbers will reach millions in a decade. We describe the artificial neural network (ANN) approach which is able to surmount the human bottleneck and permit EB-based scientific yield to keep pace with future data rates. The ANN, following training on a sample of 33,235 model light curves, outputs a set of approximate model parameters [T2/T1, (R1 + R2)/a, esin ω , ecos ω , and sin i] for each input light curve data set. The obtained parameters can then be readily passed to sophisticated modeling engines. We also describe a novel method polyfit for preprocessing observational light curves before inputting their data to the ANN and present the results and analysis of testing the approach on synthetic data and on real data including 50 binaries from the Catalog and Atlas of Eclipsing Binaries (CALEB) database and 2580 light curves from OGLE survey data. The success rate, defined by less than a 10% error in the network output parameter values, is approximately 90% for the OGLE sample and close to 100% for the CALEB sample—sufficient for a reliable statistical analysis. The code is made available to the public. Our approach is applicable to EB light curves of all classes; this first paper in the eclipsing binaries via artificial intelligence (EBAI) series focuses on detached EBs, which is the class most challenging for this approach.

Photometric study of the pulsating, eclipsing binary OO DRA

International Nuclear Information System (INIS)

Zhang, X. B.; Deng, L. C.; Tian, J. F.; Wang, K.; Yan, Z. Z.; Luo, C. Q.; Sun, J. J.; Liu, Q. L.; Xin, H. Q.; Zhou, Q.; Luo, Z. Q.

2014-01-01

We present a comprehensive photometric study of the pulsating, eclipsing binary OO Dra. Simultaneous B- and V-band photometry of the star was carried out on 14 nights. A revised orbital period and a new ephemeris were derived from the data. The first photometric solution of the binary system and the physical parameters of the component stars are determined. They reveal that OO Dra could be a detached system with a less-massive secondary component nearly filling its Roche lobe. By subtracting the eclipsing light changes from the data, we obtained the intrinsic pulsating light curves of the hotter, massive primary component. A frequency analysis of the residual light yields two confident pulsation modes in both B- and V-band data with the dominant frequency detected at 41.865 c/d. A brief discussion concerning the evolutionary status and the pulsation nature of the binary system is finally given.

Simulating Supernova Light Curves

Energy Technology Data Exchange (ETDEWEB)

Even, Wesley Paul [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Dolence, Joshua C. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

2016-05-05

This report discusses supernova light simulations. A brief review of supernovae, basics of supernova light curves, simulation tools used at LANL, and supernova results are included. Further, it happens that many of the same methods used to generate simulated supernova light curves can also be used to model the emission from fireballs generated by explosions in the earth’s atmosphere.

Simulating Supernova Light Curves

International Nuclear Information System (INIS)

Even, Wesley Paul; Dolence, Joshua C.

2016-01-01

This report discusses supernova light simulations. A brief review of supernovae, basics of supernova light curves, simulation tools used at LANL, and supernova results are included. Further, it happens that many of the same methods used to generate simulated supernova light curves can also be used to model the emission from fireballs generated by explosions in the earth's atmosphere.

Investigation of eclipsing binary stars exhibiting calcium II emission

International Nuclear Information System (INIS)

Oliver, J.P.

1974-01-01

Three color photometry of some eclipsing binaries showing Calcium II emission is reported. A highly stable and accurate d.c. amplifier, and a new type digital averaging system are described. Past and current light curves of SS Boo, RS CVn, WY Cnc, WW Dra, UV Psc, Z Her, SS Cam, RW UMa, AR Lac, and RT Lac are discussed with particular emphasis on asymmetries in the heights of the maxima and variations in the depths of the minima. Both RS CVn and SS Boo show nearly sinusoidal variation outside eclipse. Spectra of SS Boo and RS CVn are discussed. The suggestion is made that many of these systems belong to a new category of variable eclipsing binary star. It is pointed out that most double line eclipsing binaries with late-type sub-giant secondary components fall into this group, and that many of the characteristics of this group are not easily explained on the basis of existing data and theory. Possible models are discussed and the need for future photometric and spectroscopic study is emphasized. (U.S.)

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.

SEVEN NEW BINARIES DISCOVERED IN THE KEPLER LIGHT CURVES THROUGH THE BEER METHOD CONFIRMED BY RADIAL-VELOCITY OBSERVATIONS

International Nuclear Information System (INIS)

Faigler, S.; Mazeh, T.; Tal-Or, L.; Quinn, S. N.; Latham, D. W.

2012-01-01

We present seven newly discovered non-eclipsing short-period binary systems with low-mass companions, identified by the recently introduced BEER algorithm, applied to the publicly available 138-day photometric light curves obtained by the Kepler mission. The detection is based on the beaming effect (sometimes called Doppler boosting), which increases (decreases) the brightness of any light source approaching (receding from) the observer, enabling a prediction of the stellar Doppler radial-velocity (RV) modulation from its precise photometry. The BEER algorithm identifies the BEaming periodic modulation, with a combination of the well-known Ellipsoidal and Reflection/heating periodic effects, induced by short-period companions. The seven detections were confirmed by spectroscopic RV follow-up observations, indicating minimum secondary masses in the range 0.07-0.4 M ☉ . The binaries discovered establish for the first time the feasibility of the BEER algorithm as a new detection method for short-period non-eclipsing binaries, with the potential to detect in the near future non-transiting brown-dwarf secondaries, or even massive planets.

Low-mass Pre-He White Dwarf Stars in Kepler Eclipsing Binaries with Multi-periodic Pulsations

Science.gov (United States)

Zhang, X. B.; Fu, J. N.; Liu, N.; Luo, C. Q.; Ren, A. B.

2017-12-01

We report the discovery of two thermally bloated low-mass pre-He white dwarfs (WDs) in two eclipsing binaries, KIC 10989032 and KIC 8087799. Based on the Kepler long-cadence photometry, we determined comprehensive photometric solutions of the two binary systems. The light curve analysis reveals that KIC 10989032 is a partially eclipsed detached binary system containing a probable low-mass WD with the temperature of about 10,300 K. Having a WD with the temperature of about 13,300, KKIC 8087799 is typical of an EL CVn system. By utilizing radial velocity measurements available for the A-type primary star of KIC 10989032, the mass and radius of the WD component are determined to be 0.24+/- 0.02 {M}⊙ and 0.50+/- 0.01 {R}⊙ , respectively. The values of mass and radius of the WD in KIC 8087799 are estimated as 0.16 ± 0.02 M ⊙ and 0.21 ± 0.01 R ⊙, respectively, according to the effective temperature and mean density of the A-type star derived from the photometric solution. We therefore introduce KIC 10989032 and KIC 8087799 as the eleventh and twelfth dA+WD eclipsing binaries in the Kepler field. Moreover, both binaries display marked multi-periodic pulsations superimposed on binary effects. A preliminary frequency analysis is applied to the light residuals when subtracting the synthetic eclipsing light curves from the observations, revealing that the light pulsations of the two systems are both due to the δ Sct-type primaries. We hence classify KIC 10989032 and KIC 8087799 as two WD+δ Sct binaries.

Raspberry Pi Eclipse Experiments

Science.gov (United States)

Chizek Frouard, Malynda

2018-01-01

The 21 August 2017 solar eclipse was an excellent opportunity for electronics and science enthusiasts to collect data during a fascinating phenomenon. With my recent personal interest in Raspberry Pis, I thought measuring how much the temperature and illuminance changes during a total solar eclipse would be fun and informational.Previous observations of total solar eclipses have remarked on the temperature drop during totality. Illuminance (ambient light) varies over 7 orders of magnitude from day to night and is highly dependent on relative positions of Sun, Earth, and Moon. I wondered whether totality was really as dark as night.Using a Raspberry Pi Zero W, a Pimoroni Enviro pHAT, and a portable USB charger, I collected environmental temperature; CPU temperature (because the environmental temperature sensor sat very near the CPU on the Raspberry Pi); barometric pressure; ambient light; R, G, and B colors; and x, y, and z acceleration (for marking times when I moved the sensor) data at a ~15 second cadence starting at about 5 am until 1:30 pm from my eclipse observation site in Glendo, WY. Totality occurred from 11:45 to 11:47 am, lasting about 2 minutes and 30 seconds.The Raspberry Pi recorded a >20 degree F drop in temperature during the eclipse, and the illuminance during totality was equivalent to twilight measurements earlier in the day. A limitation in the ambient light sensor prevented accurate measurements of broad daylight and most of the partial phase of the eclipse, but an alternate ambient light sensor combined with the Raspberry Pi setup would make this a cost-efficient set-up for illuminance studies.I will present data from the ambient light sensor, temperature sensor, and color sensor, noting caveats from my experiments, lessons learned for next time, and suggestions for anyone who wants to perform similar experiments for themselves or with a classroom.

THE ROMER DELAY AND MASS RATIO OF THE sdB+dM BINARY 2M 1938+4603 FROM KEPLER ECLIPSE TIMINGS

Energy Technology Data Exchange (ETDEWEB)

Barlow, Brad N.; Wade, Richard A.; Liss, Sandra E. [Department of Astronomy and Astrophysics, 525 Davey Lab, Pennsylvania State University, University Park, PA 16802 (United States)

2012-07-10

The eclipsing binary system 2M 1938+4603 consists of a pulsating hot subdwarf B star and a cool M dwarf companion in an effectively circular three-hour orbit. The light curve shows both primary and secondary eclipses, along with a strong reflection effect from the cool companion. Here, we present constraints on the component masses and eccentricity derived from the Romer delay of the secondary eclipse. Using six months of publicly available Kepler photometry obtained in short-cadence mode, we fit model profiles to the primary and secondary eclipses to measure their centroid values. We find that the secondary eclipse arrives on average 2.06 {+-} 0.12 s after the midpoint between primary eclipses. Under the assumption of a circular orbit, we calculate from this time delay a mass ratio of q = 0.2691 {+-} 0.0018 and individual masses of M{sub sd} = 0.372 {+-} 0.024 M{sub Sun} and M{sub c} = 0.1002 {+-} 0.0065 M{sub Sun} for the sdB and M dwarf, respectively. These results differ slightly from those of a previously published light-curve modeling solution; this difference, however, may be reconciled with a very small eccentricity, ecos {omega} Almost-Equal-To 0.00004. We also report a decrease in the orbital period of P-dot = (-1.23 {+-} 0.07) Multiplication-Sign 10{sup -10}.

The Reflection Effect on the Eclipsing Binary by the Wilson and Devinney's Model and Russell and Merrill's Model

Directory of Open Access Journals (Sweden)

Seong Hee Choea

1992-06-01

Full Text Available The reflection effect on three types of eclipsing binaries has been analyzed Wilson and Devinney's model and Russell and Merrill's model. The reflection effect was displayed on the theoretical light curves for the various conditions using the Wilson and Devinney's light curve program. Two models were compared after the rectifing the theoretical light curves including the reflection effect with the Russell and Merrill's method. The result shows that two models have an agreement on the reflection effect just in cases of the small difference in temperature and albedo between two stars in the system.

Suzaku Observation of the Dwarf Nova V893 Scorpii: The Discovery of a Partial X-Ray Eclipse

Science.gov (United States)

Mukai, Koji; Zietsman, E.; Still, M.

2008-01-01

V893 Sco is an eclipsing dwarf nova that had attracted little attention from X-ray astronomers until it was proposed as the identification of an RXTE all-sky slew survey (XSS) source. Here we report on the po inted X-ray observations of this object using Suzaku. We confirm V893 Sco to be X-ray bright, whose spectrum is highly absorbed for a dwar f nova. We have also discovered a partial X-ray eclipse in V893 Sco. This is the first time that a partial eclipse is seen in Xray light c urves of a dwarf nova. We have successfully modeled the gross features of the optical and X-ray eclipse light curves using a boundary layer geometry of the X-ray emission region. Future observations may lead to confirmation of this basic picture, and allow us to place tight co nstraints on the size of the X-ray emission region. The partial X-ray eclipse therefore should make V893 Sco a key object in understanding the physics of accretion in quiescent dwarf nova.

Light extraction block with curved surface

Science.gov (United States)

Levermore, Peter; Krall, Emory; Silvernail, Jeffrey; Rajan, Kamala; Brown, Julia J.

2016-03-22

Light extraction blocks, and OLED lighting panels using light extraction blocks, are described, in which the light extraction blocks include various curved shapes that provide improved light extraction properties compared to parallel emissive surface, and a thinner form factor and better light extraction than a hemisphere. Lighting systems described herein may include a light source with an OLED panel. A light extraction block with a three-dimensional light emitting surface may be optically coupled to the light source. The three-dimensional light emitting surface of the block may includes a substantially curved surface, with further characteristics related to the curvature of the surface at given points. A first radius of curvature corresponding to a maximum principal curvature k.sub.1 at a point p on the substantially curved surface may be greater than a maximum height of the light extraction block. A maximum height of the light extraction block may be less than 50% of a maximum width of the light extraction block. Surfaces with cross sections made up of line segments and inflection points may also be fit to approximated curves for calculating the radius of curvature.

Full Phase Multi-Band Study of Eclipsing Binaries 1SWASP J061850.43+220511.9 and 2MASSJ07095549+3643564

Science.gov (United States)

Terheide, Rachel; Zhang, Liyun; Han, Xianming; Lu, Hongpeng

2018-01-01

We present full-phase VRI-band light curves for eclipsing binary 1SWASP J061850.43+220511.9, and full-phase BVRI-band light curves for eclipsing binary 2MASS J07095549+3643564. The observations were conducted using the 0.94-m Holcomb Observatory telescope located on Butler University Campus in Indianapolis, Indiana, and the 0.6-m SARA telescope located at the Cerro Tololo Inter-American Observatory in Chile. We obtained key system parameters for both eclipsing binaries. For 1SWASP J061850.43+220511.9, the period is 0.21482 ±0.00053 days compared to 0.21439 days from an older study (Lohr et. al), the system mass ratio is found as 2.50 and the system is classified as EW type. Similarly, for 2MASS J07095549+3643564, we obtained a linear ephemeris and a physical model for the first time. We found its period to be 0.22297 ±0.00032 days, as compared to 0.446092 days and 0.11152 days from previous research (Drake et. al 2014, Hartman et. al 2011). 2MASS J07095549+3643564 is classified as a W Uma type eclipsing binary.

ECLIPSES DURING THE 2010 ERUPTION OF THE RECURRENT NOVA U SCORPII

International Nuclear Information System (INIS)

Schaefer, Bradley E.; Pagnotta, Ashley; LaCluyze, Aaron P.; Reichart, Daniel E.; Ivarsen, Kevin M.; Haislip, Joshua B.; Nysewander, Melissa C.; Moore, Justin P.; Oksanen, Arto; Worters, Hannah L.; Sefako, Ramotholo R.; Mentz, Jaco; Dvorak, Shawn; Gomez, Tomas; Harris, Barbara G.; Henden, Arne A.; Tan, Thiam Guan; Templeton, Matthew; Allen, W. H.; Monard, Berto

2011-01-01

The eruption of the recurrent nova U Scorpii on 2010 January 28 is now the all-time best observed nova event. We report 36,776 magnitudes throughout its 67 day eruption, for an average of one measure every 2.6 minutes. This unique and unprecedented coverage is the first time that a nova has had any substantial amount of fast photometry. With this, two new phenomena have been discovered: the fast flares in the early light curve seen from days 9-15 (which have no proposed explanation) and the optical dips seen out of eclipse from days 41-61 (likely caused by raised rims of the accretion disk occulting the bright inner regions of the disk as seen over specific orbital phases). The expanding shell and wind cleared enough from days 12-15 so that the inner binary system became visible, resulting in the sudden onset of eclipses and the turn-on of the supersoft X-ray source. On day 15, a strong asymmetry in the out-of-eclipse light points to the existence of the accretion stream. The normal optical flickering restarts on day 24.5. For days 15-26, eclipse mapping shows that the optical source is spherically symmetric with a radius of 4.1 R ☉ . For days 26-41, the optical light is coming from a rim-bright disk of radius 3.4 R ☉ . For days 41-67, the optical source is a center-bright disk of radius 2.2 R ☉ . Throughout the eruption, the colors remain essentially constant. We present 12 eclipse times during eruption plus five just after the eruption.

ECLIPSES DURING THE 2010 ERUPTION OF THE RECURRENT NOVA U SCORPII

Energy Technology Data Exchange (ETDEWEB)

Schaefer, Bradley E.; Pagnotta, Ashley [Department of Physics and Astronomy, Louisiana State University, Baton Rouge, LA 70803 (United States); LaCluyze, Aaron P.; Reichart, Daniel E.; Ivarsen, Kevin M.; Haislip, Joshua B.; Nysewander, Melissa C.; Moore, Justin P. [Department of Physics and Astronomy, University of North Carolina at Chapel Hill, Chapel Hill, NC (United States); Oksanen, Arto [Caisey Harlingten Observatory, Caracoles 166, San Pedro de Atacama (Chile); Worters, Hannah L.; Sefako, Ramotholo R. [South African Astronomical Observatory, P.O. Box 9, Observatory 7935, Cape Town (South Africa); Mentz, Jaco [Unit for Space Physics, North-West University, Private Bag X6001, Potchefstroom 2520 (South Africa); Dvorak, Shawn; Gomez, Tomas; Harris, Barbara G.; Henden, Arne A.; Tan, Thiam Guan; Templeton, Matthew [American Association of Variable Star Observers, 49 Bay State Road, Cambridge, MA 02138 (United States); Allen, W. H. [Center for Backyard Astrophysics, Vintage Lane Observatory, RD 3, Blenheim (New Zealand); Monard, Berto [Center for Backyard Astrophysics, 538 W. 120th St., New York, NY 10027 (United States); and others

2011-12-01

The eruption of the recurrent nova U Scorpii on 2010 January 28 is now the all-time best observed nova event. We report 36,776 magnitudes throughout its 67 day eruption, for an average of one measure every 2.6 minutes. This unique and unprecedented coverage is the first time that a nova has had any substantial amount of fast photometry. With this, two new phenomena have been discovered: the fast flares in the early light curve seen from days 9-15 (which have no proposed explanation) and the optical dips seen out of eclipse from days 41-61 (likely caused by raised rims of the accretion disk occulting the bright inner regions of the disk as seen over specific orbital phases). The expanding shell and wind cleared enough from days 12-15 so that the inner binary system became visible, resulting in the sudden onset of eclipses and the turn-on of the supersoft X-ray source. On day 15, a strong asymmetry in the out-of-eclipse light points to the existence of the accretion stream. The normal optical flickering restarts on day 24.5. For days 15-26, eclipse mapping shows that the optical source is spherically symmetric with a radius of 4.1 R{sub Sun }. For days 26-41, the optical light is coming from a rim-bright disk of radius 3.4 R{sub Sun }. For days 41-67, the optical source is a center-bright disk of radius 2.2 R{sub Sun }. Throughout the eruption, the colors remain essentially constant. We present 12 eclipse times during eruption plus five just after the eruption.

IPHAS J062746.41+014811.3: A DEEPLY ECLIPSING INTERMEDIATE POLAR

International Nuclear Information System (INIS)

Aungwerojwit, A.; Gänsicke, B. T.; Wheatley, P. J.; Pyrzas, S.; Staels, B.; Krajci, T.; Rodríguez-Gil, P.

2012-01-01

We present time-resolved photometry of a cataclysmic variable discovered in the Isaac Newton Telescope Photometric Hα Survey of the northern galactic plane, IPHAS J062746.41+014811.3, and classify the system as the fourth deeply eclipsing intermediate polar known with an orbital period of P orb = 8.16 hr and a spin period of P spin = 2210 s. The system shows mild variations of its brightness that appear to be accompanied by a change in the amplitude of the spin modulation at optical wavelengths and a change in the morphology of the eclipse profile. The inferred magnetic moment of the white dwarf is μ wd ∼ (6-7) × 10 33 G cm 3 , and in this case IPHAS J062746.41+014811.3 will evolve either into a short-period EX Hya-like intermediate polar with a large P spin /P orb ratio or, perhaps more likely, into a synchronized polar. Swift observations show that the system is an ultraviolet and X-ray source, with a hard X-ray spectrum that is consistent with those seen in other intermediate polars. The ultraviolet light curve shows orbital modulation and an eclipse, while the low signal-to-noise ratio X-ray light curve does not show a significant modulation on the spin period. The measured X-ray flux is about an order of magnitude lower than would be expected from scaling by the optical fluxes of well-known X-ray-selected intermediate polars.

Selected results from the epsilon Aurigae eclipse campaign, and what lies ahead

Science.gov (United States)

Stencel, Robert E.

2013-07-01

The torrent of data generated during the 2009-2011 eclipse of the enigmatic binary, epsilon Aurigae, has provided abundant opportunity to test and refine the many ideas associated with this system. The UBVRIJH photometric light curves established times of ingress and egress, and also revealed that the differential color of the disk varied, relative to pre- or post- mid-eclipse phase. Inter-eclipse monitoring indicated secular variations suggestive of a rapidly evolving F supergiant star. Interferometric imaging decisively identified the eclipse-causing agent to be an opaque disk (CHARA+MIRC). Spectroscopy has shown that a hot source occupies the center of this disk (He I 10830A, Far-UV excess), that the disk exhibits substructure (K I 7699A) and may have an extended atmosphere (CHARA+VEGA), and that the disk is isotopically-enhanced in 13C (GNIRS) and in rare-earth elements during a third contact "still-stand" in the light curve, suggestive of a mass transfer stream. Polarimetry and spectro-polarimetry provided additional constraints on the F star atmospheric variation and the nature of the dust scattering in the disk. Numerical models of the disk are exploring its relationship to the wider class of transitional and debris-type disks, and how differential heating of the dust may reveal properties not otherwise detected spectroscopically. As the system moves to quadrature in coming years, continued observing opportunities will continue to exist. I am grateful for support from the estate of William Herschel Womble for astronomy at the University of Denver, which has made possible two decades of research on this star that otherwise has revealed its secrets only very slowly.

Automated Blazar Light Curves Using Machine Learning

Energy Technology Data Exchange (ETDEWEB)

Johnson, Spencer James [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

2017-07-27

This presentation describes a problem and methodology pertaining to automated blazar light curves. Namely, optical variability patterns for blazars require the construction of light curves and in order to generate the light curves, data must be filtered before processing to ensure quality.

Effects of Interstellar Dust Scattering on the X-ray Eclipses of the LMXB AX J1745.6-2901 in the Galactic Center

Science.gov (United States)

Jin, Chichuan; Ponti, Gabriele; Haberl, Frank; Smith, Randall; Valencic, Lynne

2018-04-01

AX J1745.6-2901 is an eclipsing low mass X-ray binary (LMXB) in the Galactic Centre (GC). It shows significant X-ray excess emission during the eclipse phase, and its eclipse light curve shows an asymmetric shape. We use archival XMM-Newton and Chandra observations to study the origin of these peculiar X-ray eclipsing phenomena. We find that the shape of the observed X-ray eclipse light curves depends on both photon energy and the shape of the source extraction region, and also shows differences between the two instruments. By performing detailed simulations for the time-dependent X-ray dust scattering halo, as well as directly modelling the observed eclipse and non-eclipse halo profiles of AX J1745.6-2901, we obtained solid evidence that its peculiar eclipse phenomena are indeed caused by the X-ray dust scattering in multiple foreground dust layers along the line-of-sight (LOS). The apparent dependence on the instruments is caused by different instrumental point-spread-functions. Our results can be used to assess the influence of dust scattering in other eclipsing X-ray sources, and raise the importance of considering the timing effects of dust scattering halo when studying the variability of other X-ray sources in the GC, such as Sgr A⋆. Moreover, our study of halo eclipse reinforces the existence of a dust layer local to AX J1745.6-2901 as reported by Jin et al. (2017), as well as identifying another dust layer within a few hundred parsecs to Earth, containing up to several tens of percent LOS dust, which is likely to be associated with the molecular clouds in the Solar neighbourhood. The remaining LOS dust is likely to be associated with the molecular clouds located in the Galactic disk in-between.

Detection limits for close eclipsing and transiting sub-stellar and planetary companions to white dwarfs in the WASP survey

OpenAIRE

Faedi, F.; West, R. G.; Burleigh, M. R.; Goad, M. R.; Hebb, L.

2010-01-01

We have performed extensive simulations to explore the possibility of detecting eclipses and transits of close, sub-stellar and planetary companions to white dwarfs in WASP light-curves. Our simulations cover companions $\\sim0.3\\Re

SARA South Observations and Analysis of the Solar Type, Totally Eclipsing, Over Contact Binary, PY Aquarii

Science.gov (United States)

Chamberlain, Heather; Samec, Ronald G.; Caton, Daniel Bruce; Van Hamme, Walter

2018-01-01

PY Aqr (GSC 05191-00853) is a solar Type (T ~ 5750K) eclipsing binary. It was observed in July to October, 2017 at Cerro Tololo in remote mode with the 0.6-m SARA South reflector. Two times of minimum light were calculated from our present observations, a primary and a secondary eclipse:HJD Min I = 2457951.7762±0.0006 HJD Min II = 2458019.5295±00.0003. Both weighted as 1.0.In addition, four timings were determined from online data given in IBVS 5600 and five observations at minima were determined from archived All Sky Automated Survey Data:HJD Min I = 2452908.3165, 2452912.33612 HJD Min II = 2452877.5621, 2452913.34465. All weighted as 0.5.ASAS Observations at minima: 2452094.688, 2453478.882, 2453266.576, 2452093.685 and 54729.600. Each weighted as 0.10The following linear and quadratic ephemerides were determined from all available times of minimum light:JD Hel Min I=2452951.7443±0.0008d + 0.402093441±0.000000099 X E {1} JD Hel Min I=2452951.7439±0.0007d + 0.4020912±0.0000007 X E +0.00000000018 ± 0.00000000006 X E2 {2}A BVRI Bessell filtered simultaneous Wilson-Devinney Program (W-D) solution reveals that the system has a mass ratio of ~0.34 and a component temperature difference of only ~40 K. One low luminosity (Tfact ~ 0.94, ~66 degree radius) large cool region of spots was iterated on the primary component in the WD Synthetic Light Curve computations. It appears in the Southern Hemisphere (colatitude 155 degrees). The Roche Lobe fill-out of the binary is ~17%. The inclination is ~86 degrees. An eclipse duration of ~10 minutes was determined for the primary eclipse and the light curve solution. Additional and more detailed information is given in this report.

Chromospheric activity of periodic variable stars (including eclipsing binaries) observed in DR2 LAMOST stellar spectral survey

Science.gov (United States)

Zhang, Liyun; Lu, Hongpeng; Han, Xianming L.; Jiang, Linyan; Li, Zhongmu; Zhang, Yong; Hou, Yonghui; Wang, Yuefei; Cao, Zihuang

2018-05-01

The LAMOST spectral survey provides a rich databases for studying stellar spectroscopic properties and chromospheric activity. We cross-matched a total of 105,287 periodic variable stars from several photometric surveys and databases (CSS, LINEAR, Kepler, a recently updated eclipsing star catalogue, ASAS, NSVS, some part of SuperWASP survey, variable stars from the Tsinghua University-NAOC Transient Survey, and other objects from some new references) with four million stellar spectra published in the LAMOST data release 2 (DR2). We found 15,955 spectra for 11,469 stars (including 5398 eclipsing binaries). We calculated their equivalent widths (EWs) of their Hα, Hβ, Hγ, Hδ and Caii H lines. Using the Hα line EW, we found 447 spectra with emission above continuum for a total of 316 stars (178 eclipsing binaries). We identified 86 active stars (including 44 eclipsing binaries) with repeated LAMOST spectra. A total of 68 stars (including 34 eclipsing binaries) show chromospheric activity variability. We also found LAMOST spectra of 12 cataclysmic variables, five of which show chromospheric activity variability. We also made photometric follow-up studies of three short period targets (DY CVn, HAT-192-0001481, and LAMOST J164933.24+141255.0) using the Xinglong 60-cm telescope and the SARA 90-cm and 1-m telescopes, and obtained new BVRI CCD light curves. We analyzed these light curves and obtained orbital and starspot parameters. We detected the first flare event with a huge brightness increase of more than about 1.5 magnitudes in R filter in LAMOST J164933.24+141255.0.

STRUCTURE AND DYNAMICS OF THE 2010 JULY 11 ECLIPSE WHITE-LIGHT CORONA

International Nuclear Information System (INIS)

Pasachoff, J. M.; Rusin, V.; Saniga, M.

2011-01-01

The white-light corona (WLC) during the total solar eclipse on 2010 July 11 was observed by several teams in the Moon's shadow stretching across the Pacific Ocean and a number of isolated islands. We present a comparison of the WLC as observed by eclipse teams located on the Tatakoto Atoll in French Polynesia and on Easter Island, 83 minutes later, combined with near-simultaneous space observations. The eclipse was observed at the beginning of the solar cycle, not long after solar minimum. Nevertheless, the solar corona shows a plethora of different features (coronal holes, helmet streamers, polar rays, very faint loops and radial-oriented thin streamers, a coronal mass ejection, and a puzzling 'curtain-like' object above the north pole). Comparing the observations from the two sites enables us to detect some dynamic phenomena. The eclipse observations are further compared with a hairy-ball model of the magnetic field and near-simultaneous images from the Atmospheric Imaging Assembly on NASA's Solar Dynamics Observatory, the Extreme Ultraviolet Imager on NASA's Solar Terrestrial Relations Observatory, the Sun Watcher, using Active Pixel System Detector and Image Processing on ESA's PRoject for Onboard Autonomy, and the Naval Research Laboratory's Large Angle and Spectrometric Coronagraph on ESA's Solar and Heliospheric Observatory. The Ludendorff flattening coefficient is 0.156, matching the expected ellipticity of coronal isophotes at 2 Rs un , for this rising phase of the solar-activity cycle.

Photometric and spectroscopic analysis of the eclipsing binary DS Andromedae - a member of NGC 752

International Nuclear Information System (INIS)

Schiller, S.J.; Milone, E.F.

1988-01-01

Complete BVRI light curves and radial-velocity curves of both components of the 1.01 d period eclipsing binary DS And are presented. The Wilson-Devinney synthetic light curve program is used to determine the absolute parameters of this system, and it is confirmed that the primary component is nearly filling its Roche lobe. The distance modulus and systemic velocity conclusively establish cluster membership. The age of NGC 752, determined by fitting the theoretical isochrones of VandenBerg (1985) to the C-M diagram of Cannon (1970), is assigned to DS And. This enables a showing that, although the primary component is nearly filling its Roche lobe, it has thus far evolved as a single isolated star. 54 references

LIMB-DARKENING COEFFICIENTS FOR ECLIPSING WHITE DWARFS

Energy Technology Data Exchange (ETDEWEB)

Gianninas, A.; Strickland, B. D.; Kilic, Mukremin [Homer L. Dodge Department of Physics and Astronomy, University of Oklahoma, 440 W. Brooks St., Norman, OK 73019 (United States); Bergeron, P., E-mail: alexg@nhn.ou.edu, E-mail: benstrickland@ou.edu, E-mail: kilic@ou.edu, E-mail: bergeron@astro.umontreal.ca [Departement de Physique, Universite de Montreal, C.P. 6128, Succ. Centre-Ville, Montreal, Quebec H3C 3J7 (Canada)

2013-03-20

We present extensive calculations of linear and nonlinear limb-darkening coefficients as well as complete intensity profiles appropriate for modeling the light-curves of eclipsing white dwarfs. We compute limb-darkening coefficients in the Johnson-Kron-Cousins UBVRI photometric system as well as the Large Synoptic Survey Telescope (LSST) ugrizy system using the most up to date model atmospheres available. In all, we provide the coefficients for seven different limb-darkening laws. We describe the variations of these coefficients as a function of the atmospheric parameters, including the effects of convection at low effective temperatures. Finally, we discuss the importance of having readily available limb-darkening coefficients in the context of present and future photometric surveys like the LSST, Palomar Transient Factory, and the Panoramic Survey Telescope and Rapid Response System (Pan-STARRS). The LSST, for example, may find {approx}10{sup 5} eclipsing white dwarfs. The limb-darkening calculations presented here will be an essential part of the detailed analysis of all of these systems.

LIMB-DARKENING COEFFICIENTS FOR ECLIPSING WHITE DWARFS

International Nuclear Information System (INIS)

Gianninas, A.; Strickland, B. D.; Kilic, Mukremin; Bergeron, P.

2013-01-01

We present extensive calculations of linear and nonlinear limb-darkening coefficients as well as complete intensity profiles appropriate for modeling the light-curves of eclipsing white dwarfs. We compute limb-darkening coefficients in the Johnson-Kron-Cousins UBVRI photometric system as well as the Large Synoptic Survey Telescope (LSST) ugrizy system using the most up to date model atmospheres available. In all, we provide the coefficients for seven different limb-darkening laws. We describe the variations of these coefficients as a function of the atmospheric parameters, including the effects of convection at low effective temperatures. Finally, we discuss the importance of having readily available limb-darkening coefficients in the context of present and future photometric surveys like the LSST, Palomar Transient Factory, and the Panoramic Survey Telescope and Rapid Response System (Pan-STARRS). The LSST, for example, may find ∼10 5 eclipsing white dwarfs. The limb-darkening calculations presented here will be an essential part of the detailed analysis of all of these systems.

LCC: Light Curves Classifier

Science.gov (United States)

Vo, Martin

2017-08-01

Light Curves Classifier uses data mining and machine learning to obtain and classify desired objects. This task can be accomplished by attributes of light curves or any time series, including shapes, histograms, or variograms, or by other available information about the inspected objects, such as color indices, temperatures, and abundances. After specifying features which describe the objects to be searched, the software trains on a given training sample, and can then be used for unsupervised clustering for visualizing the natural separation of the sample. The package can be also used for automatic tuning parameters of used methods (for example, number of hidden neurons or binning ratio). Trained classifiers can be used for filtering outputs from astronomical databases or data stored locally. The Light Curve Classifier can also be used for simple downloading of light curves and all available information of queried stars. It natively can connect to OgleII, OgleIII, ASAS, CoRoT, Kepler, Catalina and MACHO, and new connectors or descriptors can be implemented. In addition to direct usage of the package and command line UI, the program can be used through a web interface. Users can create jobs for ”training” methods on given objects, querying databases and filtering outputs by trained filters. Preimplemented descriptors, classifier and connectors can be picked by simple clicks and their parameters can be tuned by giving ranges of these values. All combinations are then calculated and the best one is used for creating the filter. Natural separation of the data can be visualized by unsupervised clustering.

Reflected Light Curves of Extrasolar Planets

Science.gov (United States)

Green, D.; Matthews, J.; Kuschnig, R.; Seager, S.

The planned launches of ultra-precise photometric satellites such as MOST, COROT and MONS should provide the first opportunity to study the reflected light curves from extrasolar planets. To predict the capabilities of these missions, we have constructed a series of models of such light curves, improving upon the Monte Carlo simulations by Seager et al. (2000). These models include more realistic features such limb darkening of the star and broad band photometry. For specific models, the resulting planet light curves exhibit unique behavior with the variation of radius, inclination and presence or absence of clouds.

a new approach of Analysing GRB light curves

International Nuclear Information System (INIS)

Varga, B.; Horvath, I.

2005-01-01

We estimated the T xx quantiles of the cumulative GRB light curves using our recalculated background. The basic information of the light curves was extracted by multivariate statistical methods. The possible classes of the light curves are also briefly discussed

YSOVAR: SIX PRE-MAIN-SEQUENCE ECLIPSING BINARIES IN THE ORION NEBULA CLUSTER

Energy Technology Data Exchange (ETDEWEB)

Morales-Calderon, M.; Stauffer, J. R.; Rebull, L. M. [Spitzer Science Center, California Institute of Technology, 1200 E California Blvd., Pasadena, CA 91125 (United States); Stassun, K. G. [Physics and Astronomy Department, Vanderbilt University, 1807 Station B, Nashville, TN 37235 (United States); Vrba, F. J. [U. S. Naval Observatory, Flagstaff Station, 10391 W. Naval Observatory Road, Flagstaff, AZ 86001-8521 (United States); Prato, L. [Lowell Observatory, 1400 West Mars Hill Road, Flagstaff, AZ 86001 (United States); Hillenbrand, L. A.; Carpenter, J. M. [Astronomy Department, California Institute of Technology, 1200 E California Blvd., Pasadena, CA 91125 (United States); Terebey, S.; Angione, J. [Department of Physics and Astronomy, California State University at Los Angeles, Los Angeles, CA 90032 (United States); Covey, K. R. [Department of Astronomy, Cornell University, 226 Space Sciences Building, Ithaca, NY 14853 (United States); Terndrup, D. M. [Department of Astronomy, The Ohio State University, 140 West 18th Avenue, Columbus, OH 43210 (United States); Gutermuth, R. [Department of Astronomy, University of Massachusetts, Amherst, MA 01003 (United States); Song, I. [Physics and Astronomy Department, University of Georgia, Athens, GA 30602-2451 (United States); Plavchan, P. [NASA Exoplanet Science Institute, California Institute of Technology, Pasadena, CA 91125 (United States); Marchis, F. [SETI Institute, Carl Sagan Center, 189 N San Bernado Av, Mountain View, CA 94043 (United States); Garcia, E. V. [Department of Physics, Fisk University, 1000 17th Ave. N, Nashville, TN 37208 (United States); Margheim, S. [Gemini Observatory, Southern Operations Center, Casilla 603, La Serena (Chile); Luhman, K. L. [Department of Astronomy and Astrophysics, The Pennsylvania State University, University Park, PA 16802 (United States); Irwin, J. M., E-mail: mariamc@cab.inta-csic.es [Harvard-Smithsonian Center for Astrophysics, 60 Garden St., Cambridge, MA 02138 (United States)

2012-07-10

Eclipsing binaries (EBs) provide critical laboratories for empirically testing predictions of theoretical models of stellar structure and evolution. Pre-main-sequence (PMS) EBs are particularly valuable, both due to their rarity and the highly dynamic nature of PMS evolution, such that a dense grid of PMS EBs is required to properly calibrate theoretical PMS models. Analyzing multi-epoch, multi-color light curves for {approx}2400 candidate Orion Nebula Cluster (ONC) members from our Warm Spitzer Exploration Science Program YSOVAR, we have identified 12 stars whose light curves show eclipse features. Four of these 12 EBs are previously known. Supplementing our light curves with follow-up optical and near-infrared spectroscopy, we establish two of the candidates as likely field EBs lying behind the ONC. We confirm the remaining six candidate systems, however, as newly identified ONC PMS EBs. These systems increase the number of known PMS EBs by over 50% and include the highest mass ({theta}{sup 1} Ori E, for which we provide a complete set of well-determined parameters including component masses of 2.807 and 2.797 M{sub Sun }) and longest-period (ISOY J053505.71-052354.1, P {approx} 20 days) PMS EBs currently known. In two cases ({theta}{sup 1} Ori E and ISOY J053526.88-044730.7), enough photometric and spectroscopic data exist to attempt an orbit solution and derive the system parameters. For the remaining systems, we combine our data with literature information to provide a preliminary characterization sufficient to guide follow-up investigations of these rare, benchmark systems.

YSOVAR: SIX PRE-MAIN-SEQUENCE ECLIPSING BINARIES IN THE ORION NEBULA CLUSTER

International Nuclear Information System (INIS)

Morales-Calderón, M.; Stauffer, J. R.; Rebull, L. M.; Stassun, K. G.; Vrba, F. J.; Prato, L.; Hillenbrand, L. A.; Carpenter, J. M.; Terebey, S.; Angione, J.; Covey, K. R.; Terndrup, D. M.; Gutermuth, R.; Song, I.; Plavchan, P.; Marchis, F.; García, E. V.; Margheim, S.; Luhman, K. L.; Irwin, J. M.

2012-01-01

Eclipsing binaries (EBs) provide critical laboratories for empirically testing predictions of theoretical models of stellar structure and evolution. Pre-main-sequence (PMS) EBs are particularly valuable, both due to their rarity and the highly dynamic nature of PMS evolution, such that a dense grid of PMS EBs is required to properly calibrate theoretical PMS models. Analyzing multi-epoch, multi-color light curves for ∼2400 candidate Orion Nebula Cluster (ONC) members from our Warm Spitzer Exploration Science Program YSOVAR, we have identified 12 stars whose light curves show eclipse features. Four of these 12 EBs are previously known. Supplementing our light curves with follow-up optical and near-infrared spectroscopy, we establish two of the candidates as likely field EBs lying behind the ONC. We confirm the remaining six candidate systems, however, as newly identified ONC PMS EBs. These systems increase the number of known PMS EBs by over 50% and include the highest mass (θ 1 Ori E, for which we provide a complete set of well-determined parameters including component masses of 2.807 and 2.797 M ☉ ) and longest-period (ISOY J053505.71–052354.1, P ∼ 20 days) PMS EBs currently known. In two cases (θ 1 Ori E and ISOY J053526.88–044730.7), enough photometric and spectroscopic data exist to attempt an orbit solution and derive the system parameters. For the remaining systems, we combine our data with literature information to provide a preliminary characterization sufficient to guide follow-up investigations of these rare, benchmark systems.

Deep-learnt classification of light curves

DEFF Research Database (Denmark)

Mahabal, Ashish; Gieseke, Fabian; Pai, Akshay Sadananda Uppinakudru

2017-01-01

Astronomy light curves are sparse, gappy, and heteroscedastic. As a result standard time series methods regularly used for financial and similar datasets are of little help and astronomers are usually left to their own instruments and techniques to classify light curves. A common approach is to d...

Absolute dimensions and masses of eclipsing binaries. V. IQ Persei

International Nuclear Information System (INIS)

Lacy, C.H.; Frueh, M.L.; McDonald Observatory, Austin)

1985-01-01

New photometric and spectroscopic observations of the 1.7 day eclipsing binary IQ Persei (B8 + A6) have been analyzed to yield very accurate fundamental properties of the system. Reticon spectroscopic observations obtained at McDonald Observatory were used to determine accurate radial velocities of both stars in this slightly eccentric large light-ratio binary. A new set of VR light curves obtained at McDonald Observatory were analyzed by synthesis techniques, and previously published UBV light curves were reanalyzed to yield accurate photometric orbits. Orbital parameters derived from both sets of photometric observations are in excellent agreement. The absolute dimensions, masses, luminosities, and apsidal motion period (140 yr) derived from these observations agree well with the predictions of theoretical stellar evolution models. The A6 secondary is still very close to the zero-age main sequence. The B8 primary is about one-third of the way through its main-sequence evolution. 27 references

Multiwavelength light curve parameters of Cepheid variables

Directory of Open Access Journals (Sweden)

Bhardwaj Anupam

2017-01-01

Full Text Available We present a comparative analysis of theoretical and observed light curves of Cepheid variables using Fourier decomposition. The theoretical light curves at multiple wavelengths are generated using stellar pulsation models for chemical compositions representative of Cepheids in the Galaxy and Magellanic Clouds. The observed light curves at optical (VI, near-infrared (JHKs and mid-infrared (3.6 & 4.5-μm bands are compiled from the literature. We discuss the variation of light curve parameters as a function of period, wavelength and metallicity. Theoretical and observed Fourier amplitude parameters decrease with increase in wavelength while the phase parameters increase with wavelength. We find that theoretical amplitude parameters obtained using canonical mass-luminosity levels exhibit a greater offset with respect to observations when compared to non-canonical relations. We also discuss the impact of variation in convective efficiency on the light curve structure of Cepheid variables. The increase in mixing length parameter results in a zero-point offset in bolometric mean magnitudes and reduces the systematic large difference in theoretical amplitudes with respect to observations.

PHYSICS OF ECLIPSING BINARIES. II. TOWARD THE INCREASED MODEL FIDELITY

Energy Technology Data Exchange (ETDEWEB)

Prša, A.; Conroy, K. E.; Horvat, M.; Kochoska, A.; Hambleton, K. M. [Villanova University, Dept. of Astrophysics and Planetary Sciences, 800 E Lancaster Avenue, Villanova PA 19085 (United States); Pablo, H. [Université de Montréal, Pavillon Roger-Gaudry, 2900, boul. Édouard-Montpetit Montréal QC H3T 1J4 (Canada); Bloemen, S. [Radboud University Nijmegen, Department of Astrophysics, IMAPP, P.O. Box 9010, 6500 GL, Nijmegen (Netherlands); Giammarco, J. [Eastern University, Dept. of Astronomy and Physics, 1300 Eagle Road, St. Davids, PA 19087 (United States); Degroote, P. [KU Leuven, Instituut voor Sterrenkunde, Celestijnenlaan 200D, B-3001 Heverlee (Belgium)

2016-12-01

The precision of photometric and spectroscopic observations has been systematically improved in the last decade, mostly thanks to space-borne photometric missions and ground-based spectrographs dedicated to finding exoplanets. The field of eclipsing binary stars strongly benefited from this development. Eclipsing binaries serve as critical tools for determining fundamental stellar properties (masses, radii, temperatures, and luminosities), yet the models are not capable of reproducing observed data well, either because of the missing physics or because of insufficient precision. This led to a predicament where radiative and dynamical effects, insofar buried in noise, started showing up routinely in the data, but were not accounted for in the models. PHOEBE (PHysics Of Eclipsing BinariEs; http://phoebe-project.org) is an open source modeling code for computing theoretical light and radial velocity curves that addresses both problems by incorporating missing physics and by increasing the computational fidelity. In particular, we discuss triangulation as a superior surface discretization algorithm, meshing of rotating single stars, light travel time effects, advanced phase computation, volume conservation in eccentric orbits, and improved computation of local intensity across the stellar surfaces that includes the photon-weighted mode, the enhanced limb darkening treatment, the better reflection treatment, and Doppler boosting. Here we present the concepts on which PHOEBE is built and proofs of concept that demonstrate the increased model fidelity.

The X-ray eclipse geometry of the super-soft X-ray source CAL 87

Energy Technology Data Exchange (ETDEWEB)

Ribeiro, T.; Lopes de Oliveira, R. [Departamento de Física, Universidade Federal de Sergipe, Av. Marechal Rondon s/n, 49100-000 São Cristóvão, SE (Brazil); Borges, B. W., E-mail: tribeiro@ufs.br, E-mail: rlopes@ufs.br, E-mail: bernardo@astro.ufsc.br [Universidade Federal de Santa Catarina, Campus Araranguá, 88905-120 Araranguá, SC (Brazil)

2014-09-01

We explore XMM-Newton observations of the eclipsing super-soft X-ray source CAL 87 in order to map the accretion structures of the system. Indirect imaging techniques were applied in X-ray light curves to provide eclipse maps. The surface brightness distribution exhibits an extended and symmetric emission, and a feature is revealed from the hardest X-rays that is likely due to a bright spot. A rate of P-dot =(+6±2)×10{sup −10} for changes in the orbital period of the system was derived from the eclipses. There is no significant variation of the emission lines even during eclipses, arguing that the lines are formed in an extended region. The continuum emission dominates the decrease in flux that is observed during eclipses. The O VIII Lyα line reveals a broadening velocity that is estimated to be 365{sub −69}{sup +65} km s{sup –1} (at 1σ), marginal evidence for asymmetry in its profile, and sometimes shows evidence of double-peaked emission. Together, the results support that the wind-driven mass transfer scenario is running in CAL 87.

Classification of ASKAP Vast Radio Light Curves

Science.gov (United States)

Rebbapragada, Umaa; Lo, Kitty; Wagstaff, Kiri L.; Reed, Colorado; Murphy, Tara; Thompson, David R.

2012-01-01

The VAST survey is a wide-field survey that observes with unprecedented instrument sensitivity (0.5 mJy or lower) and repeat cadence (a goal of 5 seconds) that will enable novel scientific discoveries related to known and unknown classes of radio transients and variables. Given the unprecedented observing characteristics of VAST, it is important to estimate source classification performance, and determine best practices prior to the launch of ASKAP's BETA in 2012. The goal of this study is to identify light curve characterization and classification algorithms that are best suited for archival VAST light curve classification. We perform our experiments on light curve simulations of eight source types and achieve best case performance of approximately 90% accuracy. We note that classification performance is most influenced by light curve characterization rather than classifier algorithm.

Worldwide photometry of the January 1989 Tau Persei eclipse

Science.gov (United States)

Hall, Douglas S.; Curott, David R.; Barksdale, William S.; Diethelm-Sutter, Roger; Ells, Jack

1991-01-01

New UBV photoelectric photometry of Tau Persei obtained at 19 different observatories during its recent January 1989 eclipse is presented. Mideclipse occurred at JD 2 447 542.31 + or - 0.01. The resulting light curve, though not complete at all phases, is solved for the elements with the help of two quantities derived from spectroscopy: the eclipse is 84 percent total at mideclipse, and the ratio of the radii is 0.135 + or - 0.01. Radii relative to the semimajor axis are 0.0236 for the G5 giant and 0.0032 for the A2 star. With a reasonable total mass assumed, the absolute radii say the A2 star could be luminosity class V or somewhat evolved and the G5 star is between III and II but could be closer to II. The G5 giant is brighter than the A2 star by 1.72 mag in V and the color excess in B - V is 0.06 mag, both quantities consistent (within uncertainties) with earlier estimates of Ake (1986). The eclipse duration, from first to fourth contact, is 2.09 day. The orbital inclination is 88.74 deg, consistent with what McAlister derived from speckle interferometry. Because of the large (e = 0.73) eccentricity, there is no secondary eclipse at all.

Optical and IR light curves of VV Puppis

International Nuclear Information System (INIS)

Szkody, P.; Bailey, J.A.; Hough, J.H.

1983-01-01

We present optical (0.36 to 0.6 μm) light curves with time resolutions of seconds and infrared (IR) (1.25 to 2.2 μm) light curves with time resolutions of minutes for VV Puppis during a high state. The optical light curves show a single hump with largest amplitude in the V filter, while the IR light curves show a double hump sinusoidal variation. Flickering is evident in both the optical and IR light curves, with the largest amplitude in optical B light. Through subtraction of the low state fluxes from our high state values, we obtain a flux distribution of the accretion column which peaks at 0.55 μm and becomes #betta# 2 in the IR, consistent with current cyclotron models. Comparison of the observed IR variations throughout the orbit with the expected variations due to an M4 star heated by an accretion column at an inclination of 66 0 suggests that the IR light is a combination of the secondary star plus contributions from two emitting poles. (author)

High-Resolution Infrared Spectroscopic Observations of the Upper Scorpius Eclipsing Binary EPIC 203868608

Science.gov (United States)

Johnson, Marshall C.; Mace, Gregory N.; Kim, Hwihyun; Kaplan, Kyle; McLane, Jacob; Sokal, Kimberly R.

2017-06-01

EPIC 203868608 is a source in the ~10 Myr old Upper Scorpius OB association. Using K2 photometry and ground-based follow-up observations, David et al. (2016) found that it consists of two brown dwarfs with a tertiary object at a projected separation of ~20 AU; the former objects appear to be a double-lined eclipsing binary with a period of 4.5 days. This is one of only two known eclipsing SB2s where both components are below the hydrogen-burning limit. We present additional follow-up observations of this system from the IGRINS high-resolution near-infrared spectrograph at McDonald Observatory. Our measured radial velocities do not follow the orbital solution presented by David et al. (2016). Instead, our combined IGRINS plus literature radial velocity dataset appears to indicate a period significantly different than that of the eclipsing binary obvious from the K2 light curve. We will discuss possible scenarios to account for the conflicting observations of this system.

Eclipse effects on field crops and marine zooplankton: the 29 March 2006 total solar eclipse

Science.gov (United States)

Economou, G.; Christou, E. D.; Giannakourou, A.; Gerasopoulos, E.; Georgopoulos, D.; Kotoulas, V.; Lyra, D.; Tsakalis, N.; Tzortziou, M.; Vahamidis, P.; Papathanassiou, E.; Karamanos, A.

2008-08-01

Some effects in the biosphere from the Total Solar Eclipse of 29 March 2006 were investigated in field crops and marine zooplankton. Taking into account the decisive role of light on plant life and productivity, measurements of photosynthesis and stomatal behaviour were conducted on seven important field-grown cereal and leguminous crops. A drop in photosynthetic rates, by more than a factor of 5 in some cases, was observed, and the minimum values of photosynthetic rates ranged between 3.13 and 10.13 μmol CO2 m-2 s-1. The drop in solar irradiance and the increase in mesophyll CO2-concentration during the eclipse did not induce stomatal closure thus not blocking CO2 uptake by plants. Light effects on the photochemical phase of photosynthesis may be responsible for the observed depression in photosynthetic rates. Field studies addressing the migratory responses of marine zooplankton (micro-zooplankton (ciliates), and meso-zooplankton) due to the rapid changes in underwater light intensity were also performed. The light intensity attenuation was simulated with the use of accurate underwater radiative transfer modeling techniques. Ciliates, responded to the rapid decrease in light intensity during the eclipse adopting night-time behaviour. From the meso-zooplankton assemblage, various vertical migratory behaviours were adopted by different species.

Stellar Obliquity and Magnetic Activity of Planet-hosting Stars and Eclipsing Binaries Based on Transit Chord Correlation

Science.gov (United States)

Dai, Fei; Winn, Joshua N.; Berta-Thompson, Zachory; Sanchis-Ojeda, Roberto; Albrecht, Simon

2018-04-01

The light curve of an eclipsing system shows anomalies whenever the eclipsing body passes in front of active regions on the eclipsed star. In some cases, the pattern of anomalies can be used to determine the obliquity Ψ of the eclipsed star. Here we present a method for detecting and analyzing these patterns, based on a statistical test for correlations between the anomalies observed in a sequence of eclipses. Compared to previous methods, ours makes fewer assumptions and is easier to automate. We apply it to a sample of 64 stars with transiting planets and 24 eclipsing binaries for which precise space-based data are available, and for which there was either some indication of flux anomalies or a previously reported obliquity measurement. We were able to determine obliquities for 10 stars with hot Jupiters. In particular we found Ψ ≲ 10° for Kepler-45, which is only the second M dwarf with a measured obliquity. The other eight cases are G and K stars with low obliquities. Among the eclipsing binaries, we were able to determine obliquities in eight cases, all of which are consistent with zero. Our results also reveal some common patterns of stellar activity for magnetically active G and K stars, including persistently active longitudes.

A search for planetary eclipses of white dwarfs in the Pan-STARRS1 medium-deep fields

Energy Technology Data Exchange (ETDEWEB)

Fulton, B. J.; Tonry, J. L.; Flewelling, H.; Burgett, W. S.; Chambers, K. C.; Hodapp, K. W.; Huber, M. E.; Kaiser, N.; Wainscoat, R. J.; Waters, C. [Institute for Astronomy, University of Hawaii at Manoa, Honolulu, HI 96822 (United States)

2014-12-01

We present a search for eclipses of ∼1700 white dwarfs (WDs) in the Pan-STARRS1 medium-deep fields. Candidate eclipse events are selected by identifying low outliers in over 4.3 million light curve measurements. We find no short-duration eclipses consistent with being caused by a planetary size companion. This large data set enables us to place strong constraints on the close-in planet occurrence rates around WDs for planets as small as 2 R {sub ⊕}. Our results indicate that gas giant planets orbiting just outside the Roche limit are rare, occurring around less than 0.5% of WDs. Habitable-zone super-Earths and hot super-Earths are less abundant than similar classes of planets around main-sequence stars. These constraints provide important insight into the ultimate fate of the large population of exoplanets orbiting main-sequence stars.

Dayside atmospheric structure of HD209458b from Spitzer eclipses

Science.gov (United States)

Reinhard, Matthew; Harrington, Joseph; Challener, Ryan; Cubillos, Patricio; Blecic, Jasmina

2017-10-01

HD209458b is a hot Jupiter with a radius of 1.26 ± 0.08 Jupiter radii (Richardson et al, 2006) and a mass of 0.64 ± 0.09 Jupiter masses (Snellen et al, 2010). The planet orbits a G0 type star with an orbital period of 3.52472 ± 2.81699e-05 days, and a relatively low eccentricity of 0.0082 +0.0078/-0.0082 (Wang and Ford 2013). We report the analysis of observations of HD209458b during eclipse, taken in the 3.6 and 4.5 micron channels by the Spitzer Space Telescope's Infrared Array Camera (Program 90186). We produce a photometric light curve of the eclipses in both channels, using our Photometry for Orbits Eclipses and Transits (POET) code, and calculate the brightness temperatures and eclipse depths. We also present best estimates of the atmospheric parameters of HD209458b using our Bayesian Atmospheric Radiative Transfer (BART) code. These are some preliminary results of what will be an analysis of all available Spitzer data for HD209458b. Spitzer is operated by the Jet Propulsion Laboratory, California Institute of Technology, under a contract with NASA. This work was supported by NASA Planetary Atmospheres grant NX12AI69G and NASA Astrophysics Data Analysis Program grant NNX13AF38G.

Deep-learnt classification of light curves

DEFF Research Database (Denmark)

Mahabal, Ashish; Gieseke, Fabian; Pai, Akshay Sadananda Uppinakudru

2017-01-01

is to derive statistical features from the time series and to use machine learning methods, generally supervised, to separate objects into a few of the standard classes. In this work, we transform the time series to two-dimensional light curve representations in order to classify them using modern deep......Astronomy light curves are sparse, gappy, and heteroscedastic. As a result standard time series methods regularly used for financial and similar datasets are of little help and astronomers are usually left to their own instruments and techniques to classify light curves. A common approach...... learning techniques. In particular, we show that convolutional neural networks based classifiers work well for broad characterization and classification. We use labeled datasets of periodic variables from CRTS survey and show how this opens doors for a quick classification of diverse classes with several...

Celestial shadows eclipses, transits, and occultations

CERN Document Server

Westfall, John

2015-01-01

Much of what is known about the universe comes from the study of celestial shadows—eclipses, transits, and occultations.  The most dramatic are total eclipses of the Sun, which constitute one of the most dramatic and awe-inspiring events of nature.  Though once a source of consternation or dread, solar eclipses now lead thousands of amateur astronomers and eclipse-chasers to travel to remote points on the globe to savor their beauty and the adrenaline-rush of experiencing totality, and were long the only source of information about the hauntingly beautiful chromosphere and corona of the Sun.   Long before Columbus, the curved shadow of the Earth on the Moon during a lunar eclipse revealed that we inhabit a round world. The rare and wonderful transits of Venus, which occur as it passes between the Earth and the Sun, inspired eighteenth century expeditions to measure the distance from the Earth to the Sun, while the recent transits of 2004 and 2012 were the most widely observed ever--and still produced re...

Multi-band photometric study of the short-period eclipsing binary GR Boo

Science.gov (United States)

Wang, Daimei; Zhang, Liyun; Han, Xianming L.; Lu, Hongpeng

2017-05-01

We present BVRI light curves with complete phase coverage for the short-period (p = 0.377day) eclipsing binary star GR Boo. We carried out the observations using the SARA 90 cm telescope located at Kitt Peak National Observatory. We obtained six new light curve minimum times. By fitting all of the available O-C minimum times, we obtained an updated ephemeris that shows the orbital period of GR Boo is decreasing at a rate of P˙ = - 2.36 ×10-7 days/year. This decrease in its period can be explained by either mass transfer from the more massive component to the less massive one, or angular momentum exchange due to magnetic activities. We also obtained a set of revised orbital parameters using the Wilson & Devinney program. And finally, we concluded that GR Boo is a contact binary with a dark spot.

Determinations of its Absolute Dimensions and Distance by the Analyses of Light and Radial-Velocity Curves of the Contact Binary -I. V417 Aquilae

Directory of Open Access Journals (Sweden)

Jae Woo Lee

2004-06-01

Full Text Available New photometric and spectroscopic solutions of W-type overcontact binary V417 Aql were obtained by solving the UBV light curves of Samec et al. (1997 and radial-velocity ones of Lu & Rucinski (1999 with the 2003 version of the Wilson-Devinney binary code. In the light curve synthesis the light of a third-body, which Qian (2003 proposed, was considered and obtained about 2.7%, 2.2%, and 0.4% for U, B, and V bandpasses, respectively. The model with third-light is better fitted to eclipse parts than that with no third-light. Absolute dimensions of V417 Aql are determined from our solution as M1=0.53 M⊙, M2=1.45 M⊙, R1=0.84 R⊙ and R2=1.31 M⊙, and the distance to it is deduced as about 216pc. Our distance is well consistent with that (204pc derived from Rucinski & Duerbeck's (1997 relation, MV=MV(log P, B-V, but is more distant than that (131±40pc determined by the Hipparcos trigonometric parallax. The difference may result from the relatively large error of Hipparcos parallax for V417 Aql.

A Double-line M-dwarf Eclipsing Binary from CSS × SDSS

Energy Technology Data Exchange (ETDEWEB)

Lee, Chien-Hsiu, E-mail: leech@naoj.org [Subaru Telescope, NAOJ, 650 N Aohoku Place, Hilo, HI 96720 (United States)

2017-03-01

Eclipsing binaries offer a unique opportunity to determine basic stellar properties. With the advent of wide-field camera and all-sky time-domain surveys, thousands of eclipsing binaries have been charted via light curve classification, yet their fundamental properties remain unexplored mainly due to the extensive efforts needed for spectroscopic follow-ups. In this paper, we present the discovery of a short-period ( P  = 0.313 day), double-lined M-dwarf eclipsing binary, CSSJ114804.3+255132/SDSSJ114804.35+255132.6, by cross-matching binary light curves from the Catalina Sky Survey and spectroscopically classified M dwarfs from the Sloan Digital Sky Survey. We obtain follow-up spectra using the Gemini telescope, enabling us to determine the mass, radius, and temperature of the primary and secondary component to be M {sub 1} = 0.47 ± 0.03(statistic) ± 0.03(systematic) M {sub ⊙}, M {sub 2} = 0.46 ± 0.03(statistic) ± 0.03(systematic) M {sub ⊙}, R {sub 1} = 0.52 ± 0.08(statistic) ± 0.07(systematic) R {sub ⊙}, R {sub 2} =0.60 ± 0.08(statistic) ± 0.08(systematic) R {sub ⊙}, T {sub 1} = 3560 ± 100 K, and T {sub 2} = 3040 ± 100 K, respectively. The systematic error was estimated using the difference between eccentric and non-eccentric fits. Our analysis also indicates that there is definitively third-light contamination (66%) in the CSS photometry. The secondary star seems inflated, probably due to tidal locking of the close secondary companion, which is common for very short-period binary systems. Future spectroscopic observations with high resolution will narrow down the uncertainties of stellar parameters for both components, rendering this system as a benchmark for studying fundamental properties of M dwarfs.

A Double-line M-dwarf Eclipsing Binary from CSS × SDSS

International Nuclear Information System (INIS)

Lee, Chien-Hsiu

2017-01-01

Eclipsing binaries offer a unique opportunity to determine basic stellar properties. With the advent of wide-field camera and all-sky time-domain surveys, thousands of eclipsing binaries have been charted via light curve classification, yet their fundamental properties remain unexplored mainly due to the extensive efforts needed for spectroscopic follow-ups. In this paper, we present the discovery of a short-period ( P  = 0.313 day), double-lined M-dwarf eclipsing binary, CSSJ114804.3+255132/SDSSJ114804.35+255132.6, by cross-matching binary light curves from the Catalina Sky Survey and spectroscopically classified M dwarfs from the Sloan Digital Sky Survey. We obtain follow-up spectra using the Gemini telescope, enabling us to determine the mass, radius, and temperature of the primary and secondary component to be M 1  = 0.47 ± 0.03(statistic) ± 0.03(systematic) M ⊙ , M 2  = 0.46 ± 0.03(statistic) ± 0.03(systematic) M ⊙ , R 1  = 0.52 ± 0.08(statistic) ± 0.07(systematic) R ⊙ , R 2  =0.60 ± 0.08(statistic) ± 0.08(systematic) R ⊙ , T 1  = 3560 ± 100 K, and T 2  = 3040 ± 100 K, respectively. The systematic error was estimated using the difference between eccentric and non-eccentric fits. Our analysis also indicates that there is definitively third-light contamination (66%) in the CSS photometry. The secondary star seems inflated, probably due to tidal locking of the close secondary companion, which is common for very short-period binary systems. Future spectroscopic observations with high resolution will narrow down the uncertainties of stellar parameters for both components, rendering this system as a benchmark for studying fundamental properties of M dwarfs.

Eclipse effects on field crops and marine zooplankton: the 29 March 2006 total solar eclipse

Directory of Open Access Journals (Sweden)

G. Economou

2008-08-01

Full Text Available Some effects in the biosphere from the Total Solar Eclipse of 29 March 2006 were investigated in field crops and marine zooplankton. Taking into account the decisive role of light on plant life and productivity, measurements of photosynthesis and stomatal behaviour were conducted on seven important field-grown cereal and leguminous crops. A drop in photosynthetic rates, by more than a factor of 5 in some cases, was observed, and the minimum values of photosynthetic rates ranged between 3.13 and 10.13 μmol CO₂ m⁻² s⁻¹. The drop in solar irradiance and the increase in mesophyll CO₂-concentration during the eclipse did not induce stomatal closure thus not blocking CO₂ uptake by plants. Light effects on the photochemical phase of photosynthesis may be responsible for the observed depression in photosynthetic rates. Field studies addressing the migratory responses of marine zooplankton (micro-zooplankton (ciliates, and meso-zooplankton due to the rapid changes in underwater light intensity were also performed. The light intensity attenuation was simulated with the use of accurate underwater radiative transfer modeling techniques. Ciliates, responded to the rapid decrease in light intensity during the eclipse adopting night-time behaviour. From the meso-zooplankton assemblage, various vertical migratory behaviours were adopted by different species.

SPITZER SPACE TELESCOPE MID-IR LIGHT CURVES OF NEPTUNE

Energy Technology Data Exchange (ETDEWEB)

Stauffer, John; Rebull, Luisa; Carey, Sean J.; Krick, Jessica; Ingalls, James G.; Lowrance, Patrick; Glaccum, William [Spitzer Science Center (SSC), California Institute of Technology, Pasadena, CA 91125 (United States); Marley, Mark S. [NASA Ames Research Center, Space Sciences and Astrobiology Division, MS245-3, Moffett Field, CA 94035 (United States); Gizis, John E. [Department of Physics and Astronomy, University of Delaware, Newark, DE 19716 (United States); Kirkpatrick, J. Davy [Infrared Processing and Analysis Center, MS 100-22, California Institute of Technology, Pasadena, CA 91125 (United States); Simon, Amy A. [NASA Goddard Space Flight Center, Solar System Exploration Division (690.0), 8800 Greenbelt Road, Greenbelt, MD 20771 (United States); Wong, Michael H. [University of California, Department of Astronomy, Berkeley CA 94720-3411 (United States)

2016-11-01

We have used the Spitzer Space Telescope in 2016 February to obtain high cadence, high signal-to-noise, 17 hr duration light curves of Neptune at 3.6 and 4.5 μ m. The light curve duration was chosen to correspond to the rotation period of Neptune. Both light curves are slowly varying with time, with full amplitudes of 1.1 mag at 3.6 μ m and 0.6 mag at 4.5 μ m. We have also extracted sparsely sampled 18 hr light curves of Neptune at W1 (3.4 μ m) and W2 (4.6 μ m) from the Wide-feld Infrared Survey Explorer ( WISE )/ NEOWISE archive at six epochs in 2010–2015. These light curves all show similar shapes and amplitudes compared to the Spitzer light curves but with considerable variation from epoch to epoch. These amplitudes are much larger than those observed with Kepler / K 2 in the visible (amplitude ∼0.02 mag) or at 845 nm with the Hubble Space Telescope ( HST ) in 2015 and at 763 nm in 2016 (amplitude ∼0.2 mag). We interpret the Spitzer and WISE light curves as arising entirely from reflected solar photons, from higher levels in Neptune’s atmosphere than for K 2. Methane gas is the dominant opacity source in Neptune’s atmosphere, and methane absorption bands are present in the HST 763 and 845 nm, WISE W1, and Spitzer 3.6 μ m filters.

The hidden X-ray breaks in afterglow light curves

International Nuclear Information System (INIS)

Curran, P. A.; Wijers, R. A. M. J.; Horst, A. J. van der; Starling, R. L. C.

2008-01-01

Gamma-Ray Burst (GRB) afterglow observations in the Swift era have a perceived lack of achromatic jet breaks compared to the BeppoSAX, or pre-Swift era. Specifically, relatively few breaks, consistent with jet breaks, are observed in the X-ray light curves of these bursts. If these breaks are truly missing, it has serious consequences for the interpretation of GRB jet collimation and energy requirements, and the use of GRBs as standard candles.Here we address the issue of X-ray breaks which are possibly 'hidden' and hence the light curves are misinterpreted as being single power-laws. We show how a number of precedents, including GRB 990510 and GRB 060206, exist for such hidden breaks and how, even with the well sampled light curves of the Swift era, these breaks may be left misidentified. We do so by synthesising X-ray light curves and finding general trends via Monte Carlo analysis. Furthermore, in light of these simulations, we discuss how to best identify achromatic breaks in afterglow light curves via multi-wavelength analysis

Gamma-Ray Light Curves from Pulsar Magnetospheres with Finite Conductivity

Science.gov (United States)

Harding, A. K.; Kalapotharakos, C.; Kazanas, D.; Contopoulos, I.

2012-01-01

The Fermi Large Area Telescope has provided an unprecedented database for pulsar emission studies that includes gamma-ray light curves for over 100 pulsars. Modeling these light curves can reveal and constrain the geometry of the particle accelerator, as well as the pulsar magnetic field structure. We have constructed 3D magnetosphere models with finite conductivity, that bridge the extreme vacuum and force-free solutions used in previous light curves modeling. We are investigating the shapes of pulsar gamma-ray light curves using these dissipative solutions with two different approaches: (l) assuming geometric emission patterns of the slot gap and outer gap, and (2) using the parallel electric field provided by the resistive models to compute the trajectories and . emission of the radiating particles. The light curves using geometric emission patterns show a systematic increase in gamma-ray peak phase with increasing conductivity, introducing a new diagnostic of these solutions. The light curves using the model electric fields are very sensitive to the conductivity but do not resemble the observed Fermi light curves, suggesting that some screening of the parallel electric field, by pair cascades not included in the models, is necessary

Chandra Observations of the Eclipsing Wolf-Rayet Binary CQ CepOver a Full Orbital Cycle

Science.gov (United States)

Skinner, Steve L.; Guedel, Manuel; Schmutz, Werner; Zhekov, Svetozar

2018-06-01

We present results of Chandra X-ray observations and simultaneous optical light curves of the short-period (1.64 d) eclipsing WN6+O9 binary system CQ Cep obtained in 2013 and 2017 covering a full binary orbit. Our primary objective was to compare the observed X-ray properties with colliding wind shock theory, which predicts that the hottest shock plasma (T > 20 MK) will form on or near the line-of-centers between the stars. Thus, X-ray variability is expected during eclipses when the hottest plasma is occulted. The X-ray spectrum is strikingly similar to apparently single WN6 stars such as WR 134 and spectral lines reveal plasma over a broad range of temperatures T ~ 4 - 40 MK. Both primary and secondary optical eclipses were clearly detected and provide an accurate orbital period determination (P = 1.6412 d). The X-ray emission remained remarkably steady throughout the orbit and statistical tests give a low probability of variability. The lack of significant X-ray variabililty during eclipses indicates that the X-ray emission is not confined along the line-of-centers but is extended on larger spatial scales, contrary to colliding wind predictions.

Physical Nature and Orbital Behavior of the Eclipsing System UZ Leonis

Science.gov (United States)

Lee, Jae Woo; Park, Jang-Ho

2018-03-01

New CCD photometric observations of UZ Leo were obtained between 2012 February and 2013 April, and on 2017 February. Its physical properties were derived from detailed analyses of our light curves and existing radial velocities. The results indicate that this system is a totally eclipsing A-subtype overcontact binary with both a high fill-out factor of 76% and a third light source contributing 12% light in the B bandpass, 10% in V, and 7% in R. The light residuals between observations and theoretical models are satisfactorily fitted by adopting a magnetic cool spot on the more massive primary star. Including our 12 measurements, a total of 172 eclipse times were used for ephemeris computations. We found that the orbital period of UZ Leo has varied due to a periodic oscillation superposed on an upward parabolic variation. The observed period increase at a rate of +3.49× {10}-7 day yr‑1 can be plausibly explained by some combination of non-conservative mass transfer from the secondary to the primary component and angular momentum loss due to magnetic braking. The period and semi-amplitude of the oscillation are about 139 years and 0.0225 days, respectively, which is interpreted as a light-time effect due to a third component with a mass of {M}3\\sin {i}3=0.30 {M}ȯ . Because the third lights of 7%–12% indicate that the circumbinary object is very overluminous for its mass, it would possibly match a white dwarf, rather than an M-type main sequence.

Physical Properties and Evolution of the Eclipsing Binary System XZ Canis Minoris

Science.gov (United States)

Poochaum, R.; Komonjinda, S.; Soonthornthum, B.; Rattanasoon, S.

2010-07-01

This research aims to study the eclipse binary system so that its physical properties and evolution can be determined and used as an example to teach high school astronomy. The study of an eclipsing binary system XZ Canis Minoris (XZ CMi) was done at Sirindhorn Observatory, Chiang Mai University using a 0.5-meter reflecting telescope with CCD photometric system (2184×1417 pixel) in B V and R bands of UVB System. The data obtained were used to construct the light curve for each wavelength band and to compute the times of its light minima. New elements were derived using observations with linear to all available minima. As a result, linear ephemeris is HDJmin I = .578 808 948+/-0.000 000 121+2450 515.321 26+/-0.001 07 E, and the new orbital period of XZ CMi is 0.578 808 948+/-0.000 000 121 day. The values obtained were used with the previously published times of minima to get O-C curve of XZ CMi. The result revealed that the orbital period of XZ CMi is continuously decreased at a rate of 0.007 31+/-0.000 57 sec/year. This result indicates that the binary stars are moving closer continuously. From the O-C residuals, there is significant change to indicate the existence of the third body or magnetic activity cycle on the star. However, further analysis of the physical properties of XZ CMi is required.

LUMINOSITY DISCREPANCY IN THE EQUAL-MASS, PRE-MAIN-SEQUENCE ECLIPSING BINARY PAR 1802: NON-COEVALITY OR TIDAL HEATING?

International Nuclear Information System (INIS)

Gómez Maqueo Chew, Yilen; Stassun, Keivan G.; Hebb, Leslie; Prša, Andrej; Stempels, Eric; Barnes, Rory; Heller, René; Mathieu, Robert D.

2012-01-01

Parenago 1802, a member of the ∼1 Myr Orion Nebula Cluster, is a double-lined, detached eclipsing binary in a 4.674 day orbit, with equal-mass components (M 2 /M 1 = 0.985 ± 0.029). Here we present extensive VI C JHK S light curves (LCs) spanning ∼15 yr, as well as a Keck/High Resolution Echelle Spectrometer (HIRES) optical spectrum. The LCs evince a third light source that is variable with a period of 0.73 days, and is also manifested in the high-resolution spectrum, strongly indicating the presence of a third star in the system, probably a rapidly rotating Classical T Tauri star. We incorporate this third light into our radial velocity and LC modeling of the eclipsing pair, measuring accurate masses (M 1 = 0.391 ± 0.032 and M 2 = 0.385 ± 0.032 M ☉ ), radii (R 1 = 1.73 ± 0.02 and R 2 = 1.62 ± 0.02 R ☉ ), and temperature ratio (T eff,1 /T eff,2 = 1.0924 ± 0.0017). Thus, the radii of the eclipsing stars differ by 6.9% ± 0.8%, the temperatures differ by 9.2% ± 0.2%, and consequently the luminosities differ by 62% ± 3%, despite having masses equal to within 3%. This could be indicative of an age difference of ∼3 × 10 5 yr between the two eclipsing stars, perhaps a vestige of the binary formation history. We find that the eclipsing pair is in an orbit that has not yet fully circularized, e = 0.0166 ± 0.003. In addition, we measure the rotation rate of the eclipsing stars to be 4.629 ± 0.006 days; they rotate slightly faster than their 4.674 day orbit. The non-zero eccentricity and super-synchronous rotation suggest that the eclipsing pair should be tidally interacting, so we calculate the tidal history of the system according to different tidal evolution theories. We find that tidal heating effects can explain the observed luminosity difference of the eclipsing pair, providing an alternative to the previously suggested age difference.

LUMINOSITY DISCREPANCY IN THE EQUAL-MASS, PRE-MAIN-SEQUENCE ECLIPSING BINARY PAR 1802: NON-COEVALITY OR TIDAL HEATING?

Energy Technology Data Exchange (ETDEWEB)

Gomez Maqueo Chew, Yilen; Stassun, Keivan G.; Hebb, Leslie [Department of Physics and Astronomy, Vanderbilt University, Nashville, TN 37235 (United States); Prsa, Andrej [Department of Astronomy and Astrophysics, Villanova University, Villanova, PA 19085 (United States); Stempels, Eric [Department of Astronomy and Space Physics, Uppsala University, SE-752 67 Uppsala (Sweden); Barnes, Rory [Department of Astronomy, University of Washington, Seattle, WA 98195 (United States); Heller, Rene [Leibniz-Institut fuer Astrophysik Potsdam (AIP), An der Sternwarte 16, 14482 Potsdam (Germany); Mathieu, Robert D., E-mail: yilen.gomez@vanderbilt.edu [Department of Astronomy, University of Wisconsin-Madison, Madison, WI 53706 (United States)

2012-01-20

Parenago 1802, a member of the {approx}1 Myr Orion Nebula Cluster, is a double-lined, detached eclipsing binary in a 4.674 day orbit, with equal-mass components (M{sub 2}/M{sub 1} = 0.985 {+-} 0.029). Here we present extensive VI{sub C} JHK{sub S} light curves (LCs) spanning {approx}15 yr, as well as a Keck/High Resolution Echelle Spectrometer (HIRES) optical spectrum. The LCs evince a third light source that is variable with a period of 0.73 days, and is also manifested in the high-resolution spectrum, strongly indicating the presence of a third star in the system, probably a rapidly rotating Classical T Tauri star. We incorporate this third light into our radial velocity and LC modeling of the eclipsing pair, measuring accurate masses (M{sub 1} = 0.391 {+-} 0.032 and M{sub 2} = 0.385 {+-} 0.032 M{sub Sun }), radii (R{sub 1} = 1.73 {+-} 0.02 and R{sub 2} = 1.62 {+-} 0.02 R{sub Sun }), and temperature ratio (T{sub eff,1}/T{sub eff,2} = 1.0924 {+-} 0.0017). Thus, the radii of the eclipsing stars differ by 6.9% {+-} 0.8%, the temperatures differ by 9.2% {+-} 0.2%, and consequently the luminosities differ by 62% {+-} 3%, despite having masses equal to within 3%. This could be indicative of an age difference of {approx}3 Multiplication-Sign 10{sup 5} yr between the two eclipsing stars, perhaps a vestige of the binary formation history. We find that the eclipsing pair is in an orbit that has not yet fully circularized, e = 0.0166 {+-} 0.003. In addition, we measure the rotation rate of the eclipsing stars to be 4.629 {+-} 0.006 days; they rotate slightly faster than their 4.674 day orbit. The non-zero eccentricity and super-synchronous rotation suggest that the eclipsing pair should be tidally interacting, so we calculate the tidal history of the system according to different tidal evolution theories. We find that tidal heating effects can explain the observed luminosity difference of the eclipsing pair, providing an alternative to the previously suggested age

EVEREST: Pixel Level Decorrelation of K2 Light Curves

Science.gov (United States)

Luger, Rodrigo; Agol, Eric; Kruse, Ethan; Barnes, Rory; Becker, Andrew; Foreman-Mackey, Daniel; Deming, Drake

2016-10-01

We present EPIC Variability Extraction and Removal for Exoplanet Science Targets (EVEREST), an open-source pipeline for removing instrumental noise from K2 light curves. EVEREST employs a variant of pixel level decorrelation to remove systematics introduced by the spacecraft’s pointing error and a Gaussian process to capture astrophysical variability. We apply EVEREST to all K2 targets in campaigns 0-7, yielding light curves with precision comparable to that of the original Kepler mission for stars brighter than {K}p≈ 13, and within a factor of two of the Kepler precision for fainter targets. We perform cross-validation and transit injection and recovery tests to validate the pipeline, and compare our light curves to the other de-trended light curves available for download at the MAST High Level Science Products archive. We find that EVEREST achieves the highest average precision of any of these pipelines for unsaturated K2 stars. The improved precision of these light curves will aid in exoplanet detection and characterization, investigations of stellar variability, asteroseismology, and other photometric studies. The EVEREST pipeline can also easily be applied to future surveys, such as the TESS mission, to correct for instrumental systematics and enable the detection of low signal-to-noise transiting exoplanets. The EVEREST light curves and the source code used to generate them are freely available online.

GJ 3236: A NEW BRIGHT, VERY LOW MASS ECLIPSING BINARY SYSTEM DISCOVERED BY THE MEARTH OBSERVATORY

International Nuclear Information System (INIS)

Irwin, Jonathan; Charbonneau, David; Berta, Zachory K.; Quinn, Samuel N.; Latham, David W.; Torres, Guillermo; Blake, Cullen H.; Burke, Christopher J.; Esquerdo, Gilbert A.; Fueresz, Gabor; Mink, Douglas J.; Nutzman, Philip; Szentgyorgyi, Andrew H.; Calkins, Michael L.; Falco, Emilio E.; Bloom, Joshua S.; Starr, Dan L.

2009-01-01

We report the detection of eclipses in GJ 3236, a bright (I = 11.6), very low mass binary system with an orbital period of 0.77 days. Analysis of light and radial velocity curves of the system yielded component masses of 0.38 ± 0.02 M sun and 0.28 ± 0.02 M sun . The central values for the stellar radii are larger than the theoretical models predict for these masses, in agreement with the results for existing eclipsing binaries, although the present 5% observational uncertainties limit the significance of the larger radii to approximately 1σ. Degeneracies in the light curve models resulting from the unknown configuration of surface spots on the components of GJ 3236 currently dominate the uncertainties in the radii, and could be reduced by obtaining precise, multiband photometry covering the full orbital period. The system appears to be tidally synchronized and shows signs of high activity levels as expected for such a short orbital period, evidenced by strong Hα emission lines in the spectra of both components. These observations probe an important region of mass-radius parameter space around the predicted transition to fully convective stellar interiors, where there are a limited number of precise measurements available in the literature.

Eclipsed neutrinos

International Nuclear Information System (INIS)

Anon.

1995-01-01

Full text: The total solar eclipse visible in Southern Asia on 24 October provided an opportunity for an unusual physics experiment. At face value, the levels of solar neutrinos detected on the Earth's surface are difficult to understand and suggest that perhaps the composition of solar neutrinos oscillates between different neutrino types on their journey. In this way neutrinos originating in the Sun as electrontype could convert into heavy neutrinos, which could subsequently disintegrate into an electron-neutrino and a photon. In certain neutrino scenarios, such a photon would have an energy corresponding to that of visible light, and in principle should be detectable if there are enough of them. The problem is that they would normally be swamped by the copious photons of sunlight. The 24 October solar eclipse provided a chance to check this out. A team led by François Vannucci, spokesman of the Nomad neutrino experiment at CERN, en route to the 'Rencontres du Vietnam' physics meeting in Ho Chi Minh Ville, set up a CCD-equipped telescope. To insure against cloud cover, a second telescope followed the eclipse in the desert of Rajastan, India, where the eclipse was to last only half as long, but the chance of cloud was minimal. No background solar signal was seen, or, expressed in physics terms, if solar radiation has any heavy neutrino component, then less than a millionth of it disintegrates into an electron neutrino and a visible photon before it arrives at the Earth. The negative result also has implications for candidate massive, unstable neutrinos from other sources, notably a component of the missing 'dark matter' of the Universe. The next such eclipse should be visible in North Asia in 1997, when hopefully better measurements will be made

Exploring Algorithms for Stellar Light Curves With TESS

Science.gov (United States)

Buzasi, Derek

2018-01-01

The Kepler and K2 missions have produced tens of thousands of stellar light curves, which have been used to measure rotation periods, characterize photometric activity levels, and explore phenomena such as differential rotation. The quasi-periodic nature of rotational light curves, combined with the potential presence of additional periodicities not due to rotation, complicates the analysis of these time series and makes characterization of uncertainties difficult. A variety of algorithms have been used for the extraction of rotational signals, including autocorrelation functions, discrete Fourier transforms, Lomb-Scargle periodograms, wavelet transforms, and the Hilbert-Huang transform. In addition, in the case of K2 a number of different pipelines have been used to produce initial detrended light curves from the raw image frames.In the near future, TESS photometry, particularly that deriving from the full-frame images, will dramatically further expand the number of such light curves, but details of the pipeline to be used to produce photometry from the FFIs remain under development. K2 data offers us an opportunity to explore the utility of different reduction and analysis tool combinations applied to these astrophysically important tasks. In this work, we apply a wide range of algorithms to light curves produced by a number of popular K2 pipeline products to better understand the advantages and limitations of each approach and provide guidance for the most reliable and most efficient analysis of TESS stellar data.

Interpretation of photometric observations of R Coronae Borealis. Light curves

International Nuclear Information System (INIS)

Pugach, A.F.

1990-01-01

The calculations confirm the 'reptive hypothesis' of light variations of R CrB. The central point of the hypothesis is an assertion of infinite expansion of an elementary dust cloud. The calculations for different masses of the dust cloud provide a set of elementary light curves. Superposition of the curves yields a complex light curve. The comparison with the observed minima of 1972 has been performed

Spitzer/MIPS 24 {mu}m OBSERVATIONS OF HD 209458b: THREE ECLIPSES, TWO AND A HALF TRANSITS, AND A PHASE CURVE CORRUPTED BY INSTRUMENTAL SENSITIVITY VARIATIONS

Energy Technology Data Exchange (ETDEWEB)

Crossfield, Ian J. M. [Department of Physics, and Astronomy, University of California, Los Angeles, CA 90095 (United States); Knutson, Heather [Caltech Division of Geological and Planetary Sciences, Pasadena, CA 91125 (United States); Fortney, Jonathan [Department of Astronomy and Astrophysics, University of California, Santa Cruz, CA 95064 (United States); Showman, Adam P. [Department of Planetary Sciences and Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ 85721 (United States); Cowan, Nicolas B. [Center for Interdisciplinary Exploration and Research in Astrophysics (CIERA) and Department of Physics and Astronomy, Northwestern University, Evanston, IL 60208 (United States); Deming, Drake, E-mail: ianc@astro.ucla.edu [Department of Astronomy, University of Maryland, College Park, MD 20742 (United States)

2012-06-20

We report the results of an analysis of all Spitzer/MIPS 24 {mu}m observations of HD 209458b, one of the touchstone objects in the study of irradiated giant planet atmospheres. Altogether, we analyze two and a half transits, three eclipses, and a 58 hr near-continuous observation designed to detect the planet's thermal phase curve. The results of our analysis are: (1) a mean transit depth of 1.484% {+-} 0.033%, consistent with previous measurements and showing no evidence of variability in transit depth at the 3% level. (2) A mean eclipse depth of 0.338% {+-} 0.026%, somewhat higher than that previously reported for this system; this new value brings observations into better agreement with models. From this eclipse depth we estimate an average dayside brightness temperature of 1320 {+-} 80 K; the dayside flux shows no evidence of variability at the 12% level. (3) Eclipses in the system occur 32 {+-} 129 s earlier than would be expected from a circular orbit, which constrains the orbital quantity ecos {omega} to be 0.00004 {+-} 0.00033. This result is fully consistent with a circular orbit and sets an upper limit of 140 m s{sup -1} (3{sigma}) on any eccentricity-induced velocity offset during transit. The phase curve observations (including one of the transits) exhibit an anomalous trend similar to the detector ramp seen in previous Spitzer/IRAC observations; by modeling this ramp we recover the system parameters for this transit. The long-duration photometry which follows the ramp and transit exhibits a gradual {approx}0.2% decrease in flux over {approx}30 hr. This effect is similar to that seen in pre-launch calibration data taken with the 24 {mu}m array and is better fit by an instrumental model than a model invoking planetary emission. The large uncertainties associated with this poorly understood, likely instrumental effect prevent us from usefully constraining the planet's thermal phase curve. Our observations highlight the need for a thorough

Transit Timing Variation analysis with Kepler light curves of KOI 227 and Kepler 93b

Science.gov (United States)

Dulz, Shannon; Reed, Mike

2017-01-01

By searching for transit signals in approximately 150,000 stars, NASA’s Kepler Space telescope found thousands of exoplanets over its primary mission from 2009 to 2013 (Tenenbaum et al. 2014, ApJS, 211, 6). Yet, a detailed follow-up examination of Kepler light curves may contribute more evidence on system dynamics and planetary atmospheres of these objects. Kepler’s continuous observing of these systems over the mission duration produced light curves of sufficient duration to allow for the search for transit timing variations. Transit timing variations over the course of many orbits may indicate a precessing orbit or the existence of a non-transiting third body such as another exoplanet. Flux contributions of the planet just prior to secondary eclipse may provide a measurement of bond albedo from the day-side of the transiting planet. Any asymmetries of the transit shape may indicate thermal asymmetries which can measure upper atmosphere motion of the planet. These two factors can constrain atmospheric models of close orbiting exoplanets. We first establish our procedure with the well-documented TTV system, KOI 227 (Nesvorny et al. 2014, ApJ, 790, 31). Using the test case of KOI 227, we analyze Kepler-93b for TTVs and day-side flux contributions. Kepler-93b is likely a rocky planet with R = 1.50 ± 0.03 Earth Radii and M = 2.59 ± 2.0 Earth Masses (Marcy et al. 2014, ApJS, 210, 20). This research is funded by a NASA EPSCoR grant.

A NEW CLASS OF NASCENT ECLIPSING BINARIES WITH EXTREME MASS RATIOS

Energy Technology Data Exchange (ETDEWEB)

Moe, Maxwell; Stefano, Rosanne Di, E-mail: mmoe@cfa.harvard.edu [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, MS-10, Cambridge, MA 02138 (United States)

2015-03-10

Early B-type main-sequence (MS) stars (M {sub 1} ≈ 5-16 M {sub ☉}) with closely orbiting low-mass stellar companions (q = M {sub 2}/M {sub 1} < 0.25) can evolve to produce Type Ia supernovae, low-mass X-ray binaries, and millisecond pulsars. However, the formation mechanism and intrinsic frequency of such close extreme mass-ratio binaries have been debated, especially considering none have hitherto been detected. Utilizing observations of the Large Magellanic Cloud galaxy conducted by the Optical Gravitational Lensing Experiment, we have discovered a new class of eclipsing binaries in which a luminous B-type MS star irradiates a closely orbiting low-mass pre-MS companion that has not yet fully formed. The primordial pre-MS companions have large radii and discernibly reflect much of the light they intercept from the B-type MS primaries (ΔI {sub refl} ≈ 0.02-0.14 mag). For the 18 definitive MS + pre-MS eclipsing binaries in our sample with good model fits to the observed light-curves, we measure short orbital periods P = 3.0-8.5 days, young ages τ ≈ 0.6-8 Myr, and small secondary masses M {sub 2} ≈ 0.8-2.4 M {sub ☉} (q ≈ 0.07-0.36). The majority of these nascent eclipsing binaries are still associated with stellar nurseries, e.g., the system with the deepest eclipse ΔI {sub 1} = 2.8 mag and youngest age τ = 0.6 ± 0.4 Myr is embedded in the bright H II region 30 Doradus. After correcting for selection effects, we find that (2.0 ± 0.6)% of B-type MS stars have companions with short orbital periods P = 3.0-8.5 days and extreme mass ratios q ≈ 0.06-0.25. This is ≈10 times greater than that observed for solar-type MS primaries. We discuss how these new eclipsing binaries provide invaluable insights, diagnostics, and challenges for the formation and evolution of stars, binaries, and H II regions.

Eclipse in the binary system of the CI Cyg symbiotic star

Energy Technology Data Exchange (ETDEWEB)

Belyakina, T S

1979-01-01

Photoelectric photometry and spectral observations of the symbiotic star CI Cyg were carried out at the Crimean Astrophysical Observatory from April, 1975 through December, 1976. The instrumental photometric system used was close to the UBV. Considerable light variations and spectral changes have been recorded during the period of the observations. Yellow, blue and ultraviolet amplitudes were equal to 2.3, 3.0 and 3sub(m).3 correspondingly. The brightness of CI Cyg reached maximal value in June - July, 1975 when spectrum was F5 with Hsub(..cap alpha..) and Hsub(..beta..) in emission. A sharp and deep minimum in the light curves of CI Cyg was observed during the period of the highest brightness. It was caused by the eclipse of the hot component by the cold one in the binary system.

Pre-nebular Light Curves of SNe I

Energy Technology Data Exchange (ETDEWEB)

Arnett, W. David [Steward Observatory, University of Arizona, 933 N. Cherry Avenue, Tucson, AZ 85721 (United States); Fryer, Christopher [Los Alamos National Laboratory, Los Alamos, NM (United States); Matheson, Thomas [National Optical Astronomy Observatory, Tucson, AZ (United States)

2017-09-01

We compare analytic predictions of supernova light curves with recent high-quality data from SN2011fe (Ia), KSN2011b (Ia), and the Palomar Transient Factory and the La Silla-QUEST variability survey (LSQ) (Ia). Because of the steady, fast cadence of observations, KSN2011b provides unique new information on SNe Ia: the smoothness of the light curve, which is consistent with significant large-scale mixing during the explosion, possibly due to 3D effects (e.g., Rayleigh–Taylor instabilities), and provides support for a slowly varying leakage (mean opacity). For a more complex light curve (SN2008D, SN Ib), we separate the luminosity due to multiple causes and indicate the possibility of a radioactive plume. The early rise in luminosity is shown to be affected by the opacity (leakage rate) for thermal and non-thermal radiation. A general derivation of Arnett’s rule again shows that it depends upon all processes heating the plasma, not just radioactive ones, so that SNe Ia will differ from SNe Ibc if the latter have multiple heating processes.

LONG-TERM LIGHT CURVE OF HIGHLY VARIABLE PROTOSTELLAR STAR GM CEP

International Nuclear Information System (INIS)

Xiao Limin; Kroll, Peter; Henden, Arne A.

2010-01-01

We present data from the archival plates at Harvard College Observatory and Sonneberg Observatory showing the field of the solar-type pre-main-sequence star GM Cep. A total of 186 magnitudes of GM Cep have been measured on these archival plates, with 176 in blue sensitivity, six in visible, and four in red. We combine our data with data from the literature and from the American Association of Variable Star Observers to depict the long-term light curves of GM Cep in both B and V wavelengths. The light curves span from 1895 until now, with two densely sampled regions (1935-1945 in the B band, and 2006 until now in the V band). The long-term light curves do not show any fast rise behavior as predicted by an accretion mechanism. Both the light curves and the magnitude histograms confirm the conclusion that the light curves are dominated by dips (possibly from extinction) superposed on some quiescence state, instead of outbursts caused by accretion flares. Our result excludes the possibility of GM Cep being a FUor, EXor, or McNeil's Nebula-type star. Several special cases of T Tauri stars were checked, but none of these light curves were compatible with that of GM Cep. The lack of periodicity in the light curve excludes the possibility of GM Cep being a KH 15D system.

Supervised detection of anomalous light curves in massive astronomical catalogs

International Nuclear Information System (INIS)

Nun, Isadora; Pichara, Karim; Protopapas, Pavlos; Kim, Dae-Won

2014-01-01

The development of synoptic sky surveys has led to a massive amount of data for which resources needed for analysis are beyond human capabilities. In order to process this information and to extract all possible knowledge, machine learning techniques become necessary. Here we present a new methodology to automatically discover unknown variable objects in large astronomical catalogs. With the aim of taking full advantage of all information we have about known objects, our method is based on a supervised algorithm. In particular, we train a random forest classifier using known variability classes of objects and obtain votes for each of the objects in the training set. We then model this voting distribution with a Bayesian network and obtain the joint voting distribution among the training objects. Consequently, an unknown object is considered as an outlier insofar it has a low joint probability. By leaving out one of the classes on the training set, we perform a validity test and show that when the random forest classifier attempts to classify unknown light curves (the class left out), it votes with an unusual distribution among the classes. This rare voting is detected by the Bayesian network and expressed as a low joint probability. Our method is suitable for exploring massive data sets given that the training process is performed offline. We tested our algorithm on 20 million light curves from the MACHO catalog and generated a list of anomalous candidates. After analysis, we divided the candidates into two main classes of outliers: artifacts and intrinsic outliers. Artifacts were principally due to air mass variation, seasonal variation, bad calibration, or instrumental errors and were consequently removed from our outlier list and added to the training set. After retraining, we selected about 4000 objects, which we passed to a post-analysis stage by performing a cross-match with all publicly available catalogs. Within these candidates we identified certain known

Supervised Detection of Anomalous Light Curves in Massive Astronomical Catalogs

Science.gov (United States)

Nun, Isadora; Pichara, Karim; Protopapas, Pavlos; Kim, Dae-Won

2014-09-01

The development of synoptic sky surveys has led to a massive amount of data for which resources needed for analysis are beyond human capabilities. In order to process this information and to extract all possible knowledge, machine learning techniques become necessary. Here we present a new methodology to automatically discover unknown variable objects in large astronomical catalogs. With the aim of taking full advantage of all information we have about known objects, our method is based on a supervised algorithm. In particular, we train a random forest classifier using known variability classes of objects and obtain votes for each of the objects in the training set. We then model this voting distribution with a Bayesian network and obtain the joint voting distribution among the training objects. Consequently, an unknown object is considered as an outlier insofar it has a low joint probability. By leaving out one of the classes on the training set, we perform a validity test and show that when the random forest classifier attempts to classify unknown light curves (the class left out), it votes with an unusual distribution among the classes. This rare voting is detected by the Bayesian network and expressed as a low joint probability. Our method is suitable for exploring massive data sets given that the training process is performed offline. We tested our algorithm on 20 million light curves from the MACHO catalog and generated a list of anomalous candidates. After analysis, we divided the candidates into two main classes of outliers: artifacts and intrinsic outliers. Artifacts were principally due to air mass variation, seasonal variation, bad calibration, or instrumental errors and were consequently removed from our outlier list and added to the training set. After retraining, we selected about 4000 objects, which we passed to a post-analysis stage by performing a cross-match with all publicly available catalogs. Within these candidates we identified certain known

Detection of secondary eclipses of WASP-10b and Qatar-1b in the Ks band and the correlation between Ks-band temperature and stellar activity.

Science.gov (United States)

Cruz, Patricia; Barrado, David; Lillo-Box, Jorge; Diaz, Marcos; López-Morales, Mercedes; Birkby, Jayne; Fortney, Jonathan J.; Hodgkin, Simon

2017-10-01

The Calar Alto Secondary Eclipse study was a program dedicated to observe secondary eclipses in the near-IR of two known close-orbiting exoplanets around K-dwarfs: WASP-10b and Qatar-1b. Such observations reveal hints on the orbital configuration of the system and on the thermal emission of the exoplanet, which allows the study of the brightness temperature of its atmosphere. The observations were performed at the Calar Alto Observatory (Spain). We used the OMEGA2000 instrument (Ks band) at the 3.5m telescope. The data was acquired with the telescope strongly defocused. The differential light curve was corrected from systematic effects using the Principal Component Analysis (PCA) technique. The final light curve was fitted using an occultation model to find the eclipse depth and a possible phase shift by performing a MCMC analysis. The observations have revealed a secondary eclipse of WASP-10b with depth of 0.137%, and a depth of 0.196% for Qatar-1b. The observed phase offset from expected mid-eclipse was of -0.0028 for WASP-10b, and of -0.0079 for Qatar-1b. These measured offsets led to a value for |ecosω| of 0.0044 for the WASP-10b system, leading to a derived eccentricity which was too small to be of any significance. For Qatar-1b, we have derived a |ecosω| of 0.0123, however, this last result needs to be confirmed with more data. The estimated Ks-band brightness temperatures are of 1647 K and 1885 K for WASP-10b and Qatar-1b, respectively. We also found an empirical correlation between the (R'HK) activity index of planet hosts and the Ks-band brightness temperature of exoplanets, considering a small number of systems.

VizieR Online Data Catalog: V346 Cen multiwavelength light curves (Mayer+, 2016)

Science.gov (United States)

Mayer, P.; Harmanec, P.; Wolf, M.; Nemravova, J.; Prsa, A.; Fremat, Y.; Zejda, M.; Liska, J.; Jurysek, J.; Honkova, K.; Masek, M.

2016-06-01

We present photographic light curves from O'Connell (1939, Publications of the Riverview College Observatory, 2, 5), uvby light curves from Gimenez et al. (1986A&AS...66...45G), BVR light curves from 0.6 m reflector with a CCD camera, Mt. John, New Zealand, green light curve from Sonnar 4/135mm telephoto lens with a CCD ATIK16IC camera, Sutherland, South Africa and BVRI light curves from 0.3m Meade Schmidt-Cassegrain reflector with a CCD camera. (5 data files).

SPOTTED STAR LIGHT CURVES WITH ENHANCED PRECISION

International Nuclear Information System (INIS)

Wilson, R. E.

2012-01-01

The nearly continuous timewise coverage of recent photometric surveys is free of the large gaps that compromise attempts to follow starspot growth and decay as well as motions, thereby giving incentive to improve computational precision for modeled spots. Due to the wide variety of star systems in the surveys, such improvement should apply to light/velocity curve models that accurately include all the main phenomena of close binaries and rotating single stars. The vector fractional area (VFA) algorithm that is introduced here represents surface elements by small sets of position vectors so as to allow accurate computation of circle-triangle overlap by spherical geometry. When computed by VFA, spots introduce essentially no noticeable scatter in light curves at the level of one part in 10,000. VFA has been put into the Wilson-Devinney light/velocity curve program and all logic and mathematics are given so as to facilitate entry into other such programs. Advantages of precise spot computation include improved statistics of spot motions and aging, reduced computation time (intrinsic precision relaxes needs for grid fineness), noise-free illustration of spot effects in figures, and help in guarding against false positives in exoplanet searches, where spots could approximately mimic transiting planets in unusual circumstances. A simple spot growth and decay template quantifies time profiles, and specifics of its utilization in differential corrections solutions are given. Computational strategies are discussed, the overall process is tested in simulations via solutions of synthetic light curve data, and essential simulation results are described. An efficient time smearing facility by Gaussian quadrature can deal with Kepler mission data that are in 30 minute time bins.

New inclination changing eclipsing binaries in the Magellanic Clouds

Science.gov (United States)

Juryšek, J.; Zasche, P.; Wolf, M.; Vraštil, J.; Vokrouhlický, D.; Skarka, M.; Liška, J.; Janík, J.; Zejda, M.; Kurfürst, P.; Paunzen, E.

2018-01-01

Context. Multiple stellar systems are unique laboratories for astrophysics. Analysis of their orbital dynamics, if well characterized from their observations, may reveal invaluable information about the physical properties of the participating stars. Unfortunately, there are only a few known and well described multiple systems, this is even more so for systems located outside the Milky Way galaxy. A particularly interesting situation occurs when the inner binary in a compact triple system is eclipsing. This is because the stellar interaction, typically resulting in precession of orbital planes, may be observable as a variation of depth of the eclipses on a long timescale. Aims: We aim to present a novel method to determine compact triples using publicly available photometric data from large surveys. Here we apply it to eclipsing binaries (EBs) in Magellanic Clouds from OGLE III database. Our tool consists of identifying the cases where the orbital plane of EB evolves in accord with expectations from the interaction with a third star. Methods: We analyzed light curves (LCs) of 26121 LMC and 6138 SMC EBs with the goal to identify those for which the orbital inclination varies in time. Archival LCs of the selected systems, when complemented by our own observations with Danish 1.54-m telescope, were thoroughly analyzed using the PHOEBE program. This provided physical parameters of components of each system. Time dependence of the EB's inclination was described using the theory of orbital-plane precession. By observing the parameter-dependence of the precession rate, we were able to constrain the third companion mass and its orbital period around EB. Results: We identified 58 candidates of new compact triples in Magellanic Clouds. This is the largest published sample of such systems so far. Eight of them were analyzed thoroughly and physical parameters of inner binary were determined together with an estimation of basic characteristics of the third star. Prior to our

Ultraviolet Flux Variation of Epsilon Aurigae

Directory of Open Access Journals (Sweden)

Young Woon Kang

1990-06-01

Full Text Available The eighteen ultraviolet light curves of Epsilon Aurigae have been plotted using the integrated fluxes reduced from the 233 IUE low dispersion spectra taken between 1978 and 1986. The times of contacts and depth of eclipse have been determined from the light curves at the wavelength from 2550 Å to 3050 Å. The UV light curves show two brightenings during the totality, the downward slope of the variation from the second to the third contacts, and asymmetry of the eclipse light curve. The two selected spectra note that the energy density distribution is not changed between the totality of the eclipse and out-of-eclipse.

Application of Geodetic VLBI Data to Obtaining Long-Term Light Curves for Astrophysics

Science.gov (United States)

Kijima, Masachika

2010-01-01

The long-term light curve is important to research on binary black holes and disk instability in AGNs. The light curves have been drawn mainly using single dish data provided by the University of Michigan Radio Observatory and the Metsahovi Radio Observatory. Hence, thus far, we have to research on limited sources. I attempt to draw light curves using VLBI data for those sources that have not been monitored by any observatories with single dish. I developed software, analyzed all geodetic VLBI data available at the IVS Data Centers, and drew the light curves at 8 GHz. In this report, I show the tentative results for two AGNs. I compared two light curves of 4C39.25, which were drawn based on single dish data and on VLBI data. I confirmed that the two light curves were consistent. Furthermore, I succeeded in drawing the light curve of 0454-234 with VLBI data, which has not been monitored by any observatory with single dish. In this report, I suggest that the geodetic VLBI archive data is useful to obtain the long-term light curves at radio bands for astrophysics.

CSI 2264: CHARACTERIZING YOUNG STARS IN NGC 2264 WITH STOCHASTICALLY VARYING LIGHT CURVES

Energy Technology Data Exchange (ETDEWEB)

Stauffer, John; Rebull, Luisa; Carey, Sean [Spitzer Science Center, California Institute of Technology, Pasadena, CA 91125 (United States); Cody, Ann Marie [NASA Ames Research Center, Kepler Science Office, Mountain View, CA 94035 (United States); Hillenbrand, Lynne A.; Carpenter, John [Astronomy Department, California Institute of Technology, Pasadena, CA 91125 (United States); Turner, Neal J. [Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 (United States); Terebey, Susan [Department of Physics and Astronomy, 5151 State University Drive, California State University at Los Angeles, Los Angeles, CA 90032 (United States); Morales-Calderón, Maria [Centro de Astrobiología, Dpto. de Astrofísica, INTA-CSIC, P.O. BOX 78, E-28691, ESAC Campus, Villanueva de la Cañada, Madrid (Spain); Alencar, Silvia H. P.; McGinnis, Pauline; Sousa, Alana [Departamento de Física—ICEx—UFMG, Av. Antônio Carlos, 6627, 30270-901, Belo Horizonte, MG (Brazil); Bouvier, Jerome; Venuti, Laura [Université de Grenoble, Institut de Planétologie et d’Astrophysique de Grenoble (IPAG), F-38000 Grenoble (France); Hartmann, Lee; Calvet, Nuria [Department of Astronomy, University of Michigan, 500 Church Street, Ann Arbor, MI:48105 (United States); Micela, Giusi; Flaccomio, Ettore [INAF—Osservatorio Astronomico di Palermo, Piazza del Parlamento 1, I-90134, Palermo (Italy); Song, Inseok [Department of Physics and Astronomy, The University of Georgia, Athens, GA 30602-2451 (United States); Gutermuth, Rob, E-mail: stauffer@ipac.caltech.edu [Department of Astronomy, University of Massachusetts, Amherst, MA 01003 (United States); and others

2016-03-15

We provide CoRoT and Spitzer light curves and other supporting data for 17 classical T Tauri stars in NGC 2264 whose CoRoT light curves exemplify the “stochastic” light curve class as defined in 2014 by Cody et al. The most probable physical mechanism to explain the optical variability within this light curve class is time-dependent mass accretion onto the stellar photosphere, producing transient hot spots. Where we have appropriate spectral data, we show that the veiling variability in these stars is consistent in both amplitude and timescale with the optical light curve morphology. The veiling variability is also well-correlated with the strength of the He i 6678 Å emission line, predicted by models to arise in accretion shocks on or near the stellar photosphere. Stars with accretion burst light curve morphology also have variable mass accretion. The stochastic and accretion burst light curves can both be explained by a simple model of randomly occurring flux bursts, with the stochastic light curve class having a higher frequency of lower amplitude events. Members of the stochastic light curve class have only moderate mass accretion rates. Their Hα profiles usually have blueshifted absorption features, probably originating in a disk wind. The lack of periodic signatures in the light curves suggests that little of the variability is due to long-lived hot spots rotating into or out of our line of sight; instead, the primary driver of the observed photometric variability is likely to be instabilities in the inner disk that lead to variable mass accretion.

The Kepler Light Curves of AGN: A Detailed Analysis

Science.gov (United States)

Smith, Krista Lynne; Mushotzky, Richard F.; Boyd, Patricia T.; Malkan, Matt; Howell, Steve B.; Gelino, Dawn M.

2018-04-01

We present a comprehensive analysis of 21 light curves of Type 1 active galactic nuclei (AGN) from the Kepler spacecraft. First, we describe the necessity and development of a customized pipeline for treating Kepler data of stochastically variable sources like AGN. We then present the light curves, power spectral density functions (PSDs), and flux histograms. The light curves display an astonishing variety of behaviors, many of which would not be detected in ground-based studies, including switching between distinct flux levels. Six objects exhibit PSD flattening at characteristic timescales that roughly correlate with black hole mass. These timescales are consistent with orbital timescales or free-fall accretion timescales. We check for correlations of variability and high-frequency PSD slope with accretion rate, black hole mass, redshift, and luminosity. We find that bolometric luminosity is anticorrelated with both variability and steepness of the PSD slope. We do not find evidence of the linear rms–flux relationships or lognormal flux distributions found in X-ray AGN light curves, indicating that reprocessing is not a significant contributor to optical variability at the 0.1%–10% level.

UNSUPERVISED TRANSIENT LIGHT CURVE ANALYSIS VIA HIERARCHICAL BAYESIAN INFERENCE

International Nuclear Information System (INIS)

Sanders, N. E.; Soderberg, A. M.; Betancourt, M.

2015-01-01

Historically, light curve studies of supernovae (SNe) and other transient classes have focused on individual objects with copious and high signal-to-noise observations. In the nascent era of wide field transient searches, objects with detailed observations are decreasing as a fraction of the overall known SN population, and this strategy sacrifices the majority of the information contained in the data about the underlying population of transients. A population level modeling approach, simultaneously fitting all available observations of objects in a transient sub-class of interest, fully mines the data to infer the properties of the population and avoids certain systematic biases. We present a novel hierarchical Bayesian statistical model for population level modeling of transient light curves, and discuss its implementation using an efficient Hamiltonian Monte Carlo technique. As a test case, we apply this model to the Type IIP SN sample from the Pan-STARRS1 Medium Deep Survey, consisting of 18,837 photometric observations of 76 SNe, corresponding to a joint posterior distribution with 9176 parameters under our model. Our hierarchical model fits provide improved constraints on light curve parameters relevant to the physical properties of their progenitor stars relative to modeling individual light curves alone. Moreover, we directly evaluate the probability for occurrence rates of unseen light curve characteristics from the model hyperparameters, addressing observational biases in survey methodology. We view this modeling framework as an unsupervised machine learning technique with the ability to maximize scientific returns from data to be collected by future wide field transient searches like LSST

UNSUPERVISED TRANSIENT LIGHT CURVE ANALYSIS VIA HIERARCHICAL BAYESIAN INFERENCE

Energy Technology Data Exchange (ETDEWEB)

Sanders, N. E.; Soderberg, A. M. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Betancourt, M., E-mail: nsanders@cfa.harvard.edu [Department of Statistics, University of Warwick, Coventry CV4 7AL (United Kingdom)

2015-02-10

Historically, light curve studies of supernovae (SNe) and other transient classes have focused on individual objects with copious and high signal-to-noise observations. In the nascent era of wide field transient searches, objects with detailed observations are decreasing as a fraction of the overall known SN population, and this strategy sacrifices the majority of the information contained in the data about the underlying population of transients. A population level modeling approach, simultaneously fitting all available observations of objects in a transient sub-class of interest, fully mines the data to infer the properties of the population and avoids certain systematic biases. We present a novel hierarchical Bayesian statistical model for population level modeling of transient light curves, and discuss its implementation using an efficient Hamiltonian Monte Carlo technique. As a test case, we apply this model to the Type IIP SN sample from the Pan-STARRS1 Medium Deep Survey, consisting of 18,837 photometric observations of 76 SNe, corresponding to a joint posterior distribution with 9176 parameters under our model. Our hierarchical model fits provide improved constraints on light curve parameters relevant to the physical properties of their progenitor stars relative to modeling individual light curves alone. Moreover, we directly evaluate the probability for occurrence rates of unseen light curve characteristics from the model hyperparameters, addressing observational biases in survey methodology. We view this modeling framework as an unsupervised machine learning technique with the ability to maximize scientific returns from data to be collected by future wide field transient searches like LSST.

Aspherical Supernovae: Effects on Early Light Curves

Science.gov (United States)

Afsariardchi, Niloufar; Matzner, Christopher D.

2018-04-01

Early light from core-collapse supernovae, now detectable in high-cadence surveys, holds clues to a star and its environment just before it explodes. However, effects that alter the early light have not been fully explored. We highlight the possibility of nonradial flows at the time of shock breakout. These develop in sufficiently nonspherical explosions if the progenitor is not too diffuse. When they do develop, nonradial flows limit ejecta speeds and cause ejecta–ejecta collisions. We explore these phenomena and their observational implications using global, axisymmetric, nonrelativistic FLASH simulations of simplified polytropic progenitors, which we scale to representative stars. We develop a method to track photon production within the ejecta, enabling us to estimate band-dependent light curves from adiabatic simulations. Immediate breakout emission becomes hidden as an oblique flow develops. Nonspherical effects lead the shock-heated ejecta to release a more constant luminosity at a higher, evolving color temperature at early times, effectively mixing breakout light with the early light curve. Collisions between nonradial ejecta thermalize a small fraction of the explosion energy; we will address emission from these collisions in a subsequent paper.

DETERMINING THE AGE OF THE KEPLER OPEN CLUSTER NGC 6819 WITH A NEW TRIPLE SYSTEM AND OTHER ECLIPSING BINARY STARS

International Nuclear Information System (INIS)

Brewer, Lauren N.; Sandquist, Eric L.; Jeffries, Mark W. Jr.; Orosz, Jerome A.

2016-01-01

As part of our study of the old (∼2.5 Gyr) open cluster NGC 6819 in the Kepler field, we present photometric (Kepler and ground-based BVR C I C ) and spectroscopic observations of the detached eclipsing binary WOCS 24009 (Auner 665; KIC 5023948) with a short orbital period of 3.6 days. WOCS 24009 is a triple-lined system, and we verify that the brightest star is physically orbiting the eclipsing binary using radial velocities and eclipse timing variations. The eclipsing binary components have masses M B  = 1.090 ± 0.010 M ⊙ and M C  = 1.075 ± 0.013 M ⊙ , and radii R B  = 1.099 ± 0.006 ± 0.005 R ⊙ and R C  = 1.069 ± 0.006 ± 0.013 R ⊙ . The bright non-eclipsing star resides at the cluster turnoff, and ultimately its mass will directly constrain the turnoff mass: our preliminary determination is M A  = 1.251 ± 0.057 M ⊙ . A careful examination of the light curves indicates that the fainter star in the eclipsing binary undergoes a very brief period of total eclipse, which enables us to precisely decompose the light of the three stars and place them in the color–magnitude diagram (CMD). We also present improved analysis of two previously discussed detached eclipsing stars in NGC 6819 (WOCS 40007 and WOCS 23009) en route to a combined determination of the cluster’s distance modulus (m − M) V  = 12.38 ± 0.04. Because this paper significantly increases the number of measured stars in the cluster, we can better constrain the age of the CMD to be 2.21 ± 0.10 ± 0.20 Gyr. Additionally, using all measured eclipsing binary star masses and radii, we constrain the age to 2.38 ± 0.05 ± 0.22 Gyr. The quoted uncertainties are estimates of measurement and systematic uncertainties (due to model physics differences and metal content), respectively

The "Cool Algol" BD+05 706 : Photometric observations of a new eclipsing double-lined spectroscopic binary

Science.gov (United States)

Marschall, L. A.; Torres, G.; Neuhauser, R.

1998-05-01

BVRI Observations of the star BD+05 706, carried out between January, 1997, and April 1998 using the 0.4m reflector and Photometrics CCD camera at the Gettysburg College Observatory, show that the star is an eclipsing binary system with a light curve characteristic of a class of semi-detached binaries known as the "cool Algols". These results are in good agreement with the previous report of BD+05 706 as a cool Algol by Torres, Neuhauser, and Wichmann,(Astron. J., 115, May 1998) who based their classification on the strong X-ray emission detected by Rosat and on a series of spectroscopic observations of the radial velocities of both components of the system obtained at the Oak Ridge Observatory, the Fred L. Whipple Observatory, and the Multiple Mirror Telescope. Only 10 other examples of cool Algols are known, and the current photometric light curve, together with the radial velocity curves obtained previously, allows us to derive a complete solution for the physical parameters of each component, providing important constraints on models for these interesting systems.

Rectification of light refraction in curved waveguide arrays.

Science.gov (United States)

Longhi, Stefano

2009-02-15

An "optical ratchet" for discretized light in photonic lattices, which enables observing rectification of light refraction at any input beam conditions, is theoretically presented, and a possible experimental implementation based on periodically curved zigzag waveguide arrays is proposed.

White light coronal structures and flattening during six total solar eclipses

Directory of Open Access Journals (Sweden)

B.A. Marzouk

2016-12-01

Flattening index is the first quantitative parameter introduced for analyses of the global structure of the solar corona. It varies with respect to the phase of the solar activity and sunspot number. In this paper we study the solar corona during the 1990, 1999, 2006, 2008, 2009 and 2012 total solar eclipses. We obtain flattening coefficients for all the six eclipses by using a new computer program. Our results are in a good agreement with published results.

A YOUNG ECLIPSING BINARY AND ITS LUMINOUS NEIGHBORS IN THE EMBEDDED STAR CLUSTER Sh 2-252E

Energy Technology Data Exchange (ETDEWEB)

Lester, Kathryn V.; Gies, Douglas R.; Guo, Zhao, E-mail: lester@chara.gsu.edu, E-mail: gies@chara.gsu.edu, E-mail: guo@chara.gsu.edu [Center for High Angular Resolution Astronomy and Department of Physics and Astronomy, Georgia State University, P.O. Box 5060, Atlanta, GA 30302-5060 (United States)

2016-12-01

We present a photometric and light curve analysis of an eccentric eclipsing binary in the K2 Campaign 0 field, which resides in Sh 2-252E, a young star cluster embedded in an H ii region. We describe a spectroscopic investigation of the three brightest stars in the crowded aperture to identify which is the binary system. We find that none of these stars are components of the eclipsing binary system, which must be one of the fainter nearby stars. These bright cluster members all have remarkable spectra: Sh 2-252a (EPIC 202062176) is a B0.5 V star with razor sharp absorption lines, Sh 2-252b is a Herbig A0 star with disk-like emission lines, and Sh 2-252c is a pre-main-sequence star with very red color.

Multiperiodicity in the light curve of Alpha Orionis

International Nuclear Information System (INIS)

Karovska, M.

1987-01-01

Alpha Ori, a supergiant star classified as M2 Iab, is characterized by pronounced variability encompassing most of its observed parameters. Variability on two different time scales has been observed in the light and velocity curves: a long period variation of about 6 years and superposed on this, irregular fluctuations having a time scale of several hundred days. This paper reports the results of Fourier analysis of more than 60- years of AAVSO (American Association of Variable Stars Observers) data which suggest a multiperiodicity in the light curve of α Ori

Rectification of light refraction in curved waveguide arrays

OpenAIRE

Longhi, S.

2010-01-01

An 'optical ratchet' for discretized light in photonic lattices, which enables to observe rectification of light refraction at any input beam conditions, is theoretically presented, and a possible experimental implementation based on periodically-curved zigzag waveguide arrays is proposed.

Light-Curve Diagnosis of a Hot Spot for Accretion-Disk Models

OpenAIRE

FUKUE, Jun

2003-01-01

Light curves of a hot spot rotating in a relativistic Keplerian disk were found to be periodic with typically two peaks, originating from a gravitational focusing effect and a Doppler boost. On the other hand, we found that light curves of a hot spot spirally infalling in a sub-Keplerian advective disk are aperiodic with typically a single peak, originating from a gravitational focusing effect or a Doppler boost. Such a difference in the light curves of a hot spot can discriminate background ...

Light Curve Solution of the Contact Binary AW UMa

Directory of Open Access Journals (Sweden)

J. H. Jeong

1997-12-01

Full Text Available A total of 1088 observations (272 in B,272 in V, 272 in R, and 272 in I were made from January to February in 1995 at Chungbuk National University observatory(CbNUO. We constructed BVRI light curves with our data. The photometric solution of these light curves was obtained by means of the Wilson-Devinney method. Our result was compared with those by previous investigators.

Gamma-Ray Pulsar Light Curves as Probes of Magnetospheric Structure

Science.gov (United States)

Harding, A. K.

2016-01-01

The large number of gamma-ray pulsars discovered by the Fermi Gamma-Ray Space Telescope since its launch in 2008 dwarfs the handful that were previously known. The variety of observed light curves makes possible a tomography of both the ensemble-averaged field structure and the high-energy emission regions of a pulsar magnetosphere. Fitting the gamma-ray pulsar light curves with model magnetospheres and emission models has revealed that most of the high-energy emission, and the particles acceleration, takes place near or beyond the light cylinder, near the current sheet. As pulsar magnetosphere models become more sophisticated, it is possible to probe magnetic field structure and emission that are self-consistently determined. Light curve modeling will continue to be a powerful tool for constraining the pulsar magnetosphere physics.

Timescale stretch parameterization of Type Ia supernova B-band light curves

International Nuclear Information System (INIS)

Goldhaber, G.; Groom, D.E.; Kim, A.; Aldering, G.; Astier, P.; Conley, A.; Deustua, S.E.; Ellis, R.; Fabbro, S.; Fruchter, A.S.; Goobar, A.; Hook, I.; Irwin, M.; Kim, M.; Knop, R.A.; Lidman, C.; McMahon, R.; Nugent, P.E.; Pain, R.; Panagia, N.; Pennypacker, C.R.; Perlmutter, S.; Ruiz-Lapuente, P.; Schaefer, B.; Walton, N.A.; York, T.

2001-01-01

R-band intensity measurements along the light curve of Type Ia supernovae discovered by the Cosmology Project (SCP) are fitted in brightness to templates allowing a free parameter the time-axis width factor w identically equal to s times (1+z). The data points are then individually aligned in the time-axis, normalized and K-corrected back to the rest frame, after which the nearly 1300 normalized intensity measurements are found to lie on a well-determined common rest-frame B-band curve which we call the ''composite curve.'' The same procedure is applied to 18 low-redshift Calan/Tololo SNe with Z < 0.11; these nearly 300 B-band photometry points are found to lie on the composite curve equally well. The SCP search technique produces several measurements before maximum light for each supernova. We demonstrate that the linear stretch factor, s, which parameterizes the light-curve timescale appears independent of z, and applies equally well to the declining and rising parts of the light curve. In fact, the B band template that best fits this composite curve fits the individual supernova photometry data when stretched by a factor s with chi 2/DoF ∼ 1, thus as well as any parameterization can, given the current data sets. The measurement of the data of explosion, however, is model dependent and not tightly constrained by the current data. We also demonstrate the 1 + z light-cure time-axis broadening expected from cosmological expansion. This argues strongly against alternative explanations, such as tired light, for the redshift of distant objects

QUEST1 Variability Survey. III. Light Curve Catalog Update

Science.gov (United States)

Rengstorf, A. W.; Thompson, D. L.; Mufson, S. L.; Andrews, P.; Honeycutt, R. K.; Vivas, A. K.; Abad, C.; Adams, B.; Bailyn, C.; Baltay, C.; Bongiovanni, A.; Briceño, C.; Bruzual, G.; Coppi, P.; Della Prugna, F.; Emmet, W.; Ferrín, I.; Fuenmayor, F.; Gebhard, M.; Hernández, J.; Magris, G.; Musser, J.; Naranjo, O.; Oemler, A.; Rosenzweig, P.; Sabbey, C. N.; Sánchez, Ge.; Sánchez, Gu.; Schaefer, B.; Schenner, H.; Sinnott, J.; Snyder, J. A.; Sofia, S.; Stock, J.; van Altena, W.

2009-03-01

This paper reports an update to the QUEST1 (QUasar Equatorial Survey Team, Phase 1) Variability Survey (QVS) light curve catalog, which links QVS instrumental magnitude light curves to Sloan Digital Sky Survey (SDSS) objects and photometry. In the time since the original QVS catalog release, the overlap between publicly available SDSS data and QVS data has increased by 8% in sky coverage and 16,728 in number of matched objects. The astrometric matching and the treatment of SDSS masks have been refined for the updated catalog. We report on these improvements and present multiple bandpass light curves, global variability information, and matched SDSS photometry for 214,941 QUEST1 objects. Based on observations obtained at the Llano del Hato National Astronomical Observatory, operated by the Centro de Investigaciones de Astronomía for the Ministerio de Ciencia y Tecnologia of Venezuela.

Discovery of 36 eclipsing EL CVn binaries found by the Palomar Transient Factory

Science.gov (United States)

van Roestel, J.; Kupfer, T.; Ruiz-Carmona, R.; Groot, P. J.; Prince, T. A.; Burdge, K.; Laher, R.; Shupe, D. L.; Bellm, E.

2018-04-01

We report on the discovery and analysis of 36 new eclipsing EL CVn-type binaries, consisting of a core helium-composition pre-white dwarf (pre-He-WD) and an early-type main-sequence companion. This more than doubles the known population of these systems. We have used supervised machine learning methods to search 0.8 million light curves from the Palomar Transient Factory (PTF), combined with Sloan Digital Sky Survey (SDSS), Panoramic Survey Telescope and Rapid Response System (Pan-STARRS) and Two-Micron All-Sky Survey (2MASS) colours. The new systems range in orbital periods from 0.46 to 3.8 d and in apparent brightness from ˜14 to 16 mag in the PTF R or g΄ filters. For 12 of the systems, we obtained radial velocity curves with the Intermediate Dispersion Spectrograph at the Isaac Newton Telescope. We modelled the light curves, radial velocity curves and spectral energy distributions to determine the system parameters. The radii (0.3-0.7 R⊙) and effective temperatures (8000-17 000 K) of the pre-He-WDs are consistent with stellar evolution models, but the masses (0.12-0.28 M⊙) show more variance than models have predicted. This study shows that using machine learning techniques on large synoptic survey data is a powerful way to discover substantial samples of binary systems in short-lived evolutionary stages.

Luminosity change in DQ Herculis

International Nuclear Information System (INIS)

Nelson, M.R.; Olson, E.C.

1976-01-01

The 1975 observations show a dramatic change in the UBV light curves of the eclipsing binary DQ Her (nova 1934). Since 1954, the B light outside eclipse has dimmed approximately 0.5 mag and the light at primary minimum has dimmed approximately 1.3 mag. Simple analysis of the light curves allows one to conclude that (1) the eclipsed light has fallen approximately 20 percent while the light which is constant with orbital phase has dropped approximately 75 percent; (2) the time over which most of the change in the eclipsed light occurred is less than approximately 0.7 years; (3) light loss at mid-eclipse is approximately 0.94; and (4) the mass of the secondary star is less than 0.4 M/sub solar mass/. The changes provide indirect evidence that the mass transfer rate is not constant in time. Near-infrared data are also presented which show a reversal of the trend seen in the UBV light curves of greater eclipse depth with longer wavelength

Exquisite Nova Light Curves from the Solar Mass Ejection Imager (SMEI)

OpenAIRE

Hounsell, R.; Bode, M. F.; Hick, P. P.; Buffington, A.; Jackson, B. V.; Clover, J. M.; Shafter, A. W.; Darnley, M. J.; Mawson, N. R.; Steele, I. A.; Evans, A.; Eyres, S. P. S.; O'Brien, T. J.

2010-01-01

We present light curves of three classical novae (KT Eridani, V598 Puppis, V1280 Scorpii) and one recurrent nova (RS Ophiuchi) derived from data obtained by the Solar Mass Ejection Imager (SMEI) on board the Coriolis satellite. SMEI provides near complete sky-map coverage with precision visible-light photometry at 102-minute cadence. The light curves derived from these sky maps offer unprecedented temporal resolution around, and especially before, maximum light, a phase of the nova eruption n...

TYPE Ia SUPERNOVA LIGHT-CURVE INFERENCE: HIERARCHICAL BAYESIAN ANALYSIS IN THE NEAR-INFRARED

International Nuclear Information System (INIS)

Mandel, Kaisey S.; Friedman, Andrew S.; Kirshner, Robert P.; Wood-Vasey, W. Michael

2009-01-01

We present a comprehensive statistical analysis of the properties of Type Ia supernova (SN Ia) light curves in the near-infrared using recent data from Peters Automated InfraRed Imaging TELescope and the literature. We construct a hierarchical Bayesian framework, incorporating several uncertainties including photometric error, peculiar velocities, dust extinction, and intrinsic variations, for principled and coherent statistical inference. SN Ia light-curve inferences are drawn from the global posterior probability of parameters describing both individual supernovae and the population conditioned on the entire SN Ia NIR data set. The logical structure of the hierarchical model is represented by a directed acyclic graph. Fully Bayesian analysis of the model and data is enabled by an efficient Markov Chain Monte Carlo algorithm exploiting the conditional probabilistic structure using Gibbs sampling. We apply this framework to the JHK s SN Ia light-curve data. A new light-curve model captures the observed J-band light-curve shape variations. The marginal intrinsic variances in peak absolute magnitudes are σ(M J ) = 0.17 ± 0.03, σ(M H ) = 0.11 ± 0.03, and σ(M Ks ) = 0.19 ± 0.04. We describe the first quantitative evidence for correlations between the NIR absolute magnitudes and J-band light-curve shapes, and demonstrate their utility for distance estimation. The average residual in the Hubble diagram for the training set SNe at cz > 2000kms -1 is 0.10 mag. The new application of bootstrap cross-validation to SN Ia light-curve inference tests the sensitivity of the statistical model fit to the finite sample and estimates the prediction error at 0.15 mag. These results demonstrate that SN Ia NIR light curves are as effective as corrected optical light curves, and, because they are less vulnerable to dust absorption, they have great potential as precise and accurate cosmological distance indicators.

Ultraviolet, optical and infra-red observations of the Wolf-Rayet contact-eclipsing binary CQ Cephei

International Nuclear Information System (INIS)

Stickland, D.J.; Budding, E.; Howarth, I.D.; Willis, A.J.; Jameson, R.; Sherrington, M.R.; Bromage, G.E.; Burton, W.M.

1984-01-01

The present study on wolf-rayet contact-eclipsing binary CQ Cephei is an attempt to combine the best observational previous results with an extensive set of UV data from the IUE Satellite and with new IR photometric data. The orbital variations of the CQ Cep system are investigated as well as the secondary component. The early studies of CQ Cep are reviewed, and the observations used in the present analysis described. Continuum energy distribution, interstellar extinction, photometric variability, light curves, time dependence of the emission and absorption line spectra and models for the CQ Cept system are discussed. (U.K.)

PHYSICAL PROPERTIES OF THE LOW-MASS ECLIPSING BINARY NSVS 02502726

Energy Technology Data Exchange (ETDEWEB)

Lee, Jae Woo; Youn, Jae-Hyuck; Kim, Seung-Lee; Lee, Chung-Uk, E-mail: jwlee@kasi.re.kr, E-mail: jhyoon@kasi.re.kr, E-mail: slkim@kasi.re.kr, E-mail: leecu@kasi.re.kr [Korea Astronomy and Space Science Institute, Daejon 305-348 (Korea, Republic of)

2013-01-01

NSVS 02502726 has been known as a double-lined, detached eclipsing binary that consists of two low-mass stars. We obtained BVRI photometric follow-up observations in 2009 and 2011 to measure improved physical properties of the binary star. Each set of light curves, including the 2008 data given by Cakirli et al., was simultaneously analyzed with the previously published radial velocity curves using the Wilson-Devinney binary code. The conspicuous seasonal light variations of the system are satisfactorily modeled by a two-spot model with one starspot on each component and by changes of the spot parameters with time. Based on 23 eclipse timings calculated from the synthetic model and one ephemeris epoch, an orbital period study of NSVS 02502726 reveals that the period has experienced a continuous decrease of -5.9 Multiplication-Sign 10{sup -7} day yr{sup -1} or a sinusoidal variation with a period and semi-amplitude of 2.51 yr and 0.0011 days, respectively. The timing variations could be interpreted as either the light-travel-time effect due to the presence of an unseen third body, or as the combination of this effect and angular momentum loss via magnetic stellar wind braking. Individual masses and radii of both components are determined to be M{sub 1} = 0.689 {+-} 0.016 M{sub Sun }, M{sub 2} = 0.341 {+-} 0.009 M{sub Sun }, R{sub 1} = 0.707 {+-} 0.007 R{sub Sun }, and R{sub 2} = 0.657 {+-} 0.008 R{sub Sun }. The results are very different from those of Cakirli et al. with the primary's radius (0.674 {+-} 0.006 R{sub Sun }) smaller the secondary's (0.763 {+-} 0.007 R{sub Sun }). We compared the physical parameters presented in this paper with current low-mass stellar models and found that the measured values of the primary star are best fitted to a 79 Myr isochrone. The primary is in good agreement with the empirical mass-radius relation from low-mass binaries, but the secondary is oversized by about 85%.

Infrared and optical light curves of EX Hydrae and VW Hydri

International Nuclear Information System (INIS)

Sherrington, M.R.; Lawson, P.A.; King, A.R.; Jameson, R.F.

1980-01-01

Optical and infrared light curves of EX Hya (V and K) and VW Hyi (J and K) are presented. The infrared colours imply very large discs for these systems. It is also found for EX Hya that the structure of the light curves is non-repeatable. (author)

BEER ANALYSIS OF KEPLER AND CoRoT LIGHT CURVES. I. DISCOVERY OF KEPLER-76b: A HOT JUPITER WITH EVIDENCE FOR SUPERROTATION

International Nuclear Information System (INIS)

Faigler, S.; Tal-Or, L.; Mazeh, T.; Latham, D. W.; Buchhave, L. A.

2013-01-01

We present the first case in which the BEER algorithm identified a hot Jupiter in the Kepler light curve, and its reality was confirmed by orbital solutions based on follow-up spectroscopy. The companion Kepler-76b was identified by the BEER algorithm, which detected the BEaming (sometimes called Doppler boosting) effect together with the Ellipsoidal and Reflection/emission modulations (BEER), at an orbital period of 1.54 days, suggesting a planetary companion orbiting the 13.3 mag F star. Further investigation revealed that this star appeared in the Kepler eclipsing binary catalog with estimated primary and secondary eclipse depths of 5 × 10 –3 and 1 × 10 –4 , respectively. Spectroscopic radial velocity follow-up observations with Tillinghast Reflector Echelle Spectrograph and SOPHIE confirmed Kepler-76b as a transiting 2.0 ± 0.26 M Jup hot Jupiter. The mass of a transiting planet can be estimated from either the beaming or the ellipsoidal amplitude. The ellipsoidal-based mass estimate of Kepler-76b is consistent with the spectroscopically measured mass while the beaming-based estimate is significantly inflated. We explain this apparent discrepancy as evidence for the superrotation phenomenon, which involves eastward displacement of the hottest atmospheric spot of a tidally locked planet by an equatorial superrotating jet stream. This phenomenon was previously observed only for HD 189733b in the infrared. We show that a phase shift of 10.°3 ± 2.°0 of the planet reflection/emission modulation, due to superrotation, explains the apparently inflated beaming modulation, resolving the ellipsoidal/beaming amplitude discrepancy. Kepler-76b is one of very few confirmed planets in the Kepler light curves that show BEER modulations and the first to show superrotation evidence in the Kepler band. Its discovery illustrates for the first time the ability of the BEER algorithm to detect short-period planets and brown dwarfs.

VizieR Online Data Catalog: Detached M dwarf eclipsing binaries in WTS (Birkby+, 2012)

Science.gov (United States)

Birkby, J.; Nefs, B.; Hodgkin, S.; Kovacs, G.; Sipocz, B.; Pinfield, D.; Snellen, I.; Mislis, D.; Murgas, F.; Lodieu, N.; de Mooij, E.; Goulding, N.; Cruz, P.; Stoev, H.; Cappetta, M.; Palle, E.; Barrado, D.; Saglia, R.; Martin, E.; Pavlenko, Y.

2013-04-01

We identified our new MEBs using observations from the WTS (WFCAM Transit Survey). The WTS is an ongoing photometric monitoring campaign that operates on the 3.8-m United Kingdom Infrared Telescope (UKIRT) at Mauna Kea, Hawaii. The survey began on 2007 August 5, and the eclipsing systems presented in this paper are all found in just one of the four WTS fields. Photometric follow-up observations to help test and refine our light-curve models were obtained in the Sloan i band using the Wide-Field Camera (WFC) on the 2.5-m INT at Roque de Los Muchachos, La Palma. (6 data files).

Intensive Monitoring Survey of Nearby Galaxies (IMSNG): Catching Early Light Curves of Supernovae

Science.gov (United States)

Im, Myungshin; IMSNG Team

2018-01-01

SNe light curves have been used to study the expansion history of the universe, and a lot of efforts have gone into understanding the overall shape of the radioactively powered light curve. However, we still have little direct observational evidence for the theorized SN progenitor systems. Recent studies suggest that the light curve of a supernova shortly after its explosion (world. Through this survey, we expect to catch the very early precursor emission as faint as R=21 mag (~0.1 Rsun for the progenitor). This poster outlines this project, and present a few scientific highlights, such as the early light curve of SN 2015F in NGC 2442.

RED GIANTS IN ECLIPSING BINARY AND MULTIPLE-STAR SYSTEMS: MODELING AND ASTEROSEISMIC ANALYSIS OF 70 CANDIDATES FROM KEPLER DATA

International Nuclear Information System (INIS)

Gaulme, P.; McKeever, J.; Rawls, M. L.; Jackiewicz, J.; Mosser, B.; Guzik, J. A.

2013-01-01

Red giant stars are proving to be an incredible source of information for testing models of stellar evolution, as asteroseismology has opened up a window into their interiors. Such insights are a direct result of the unprecedented data from space missions CoRoT and Kepler as well as recent theoretical advances. Eclipsing binaries are also fundamental astrophysical objects, and when coupled with asteroseismology, binaries provide two independent methods to obtain masses and radii and exciting opportunities to develop highly constrained stellar models. The possibility of discovering pulsating red giants in eclipsing binary systems is therefore an important goal that could potentially offer very robust characterization of these systems. Until recently, only one case has been discovered with Kepler. We cross-correlate the detected red giant and eclipsing-binary catalogs from Kepler data to find possible candidate systems. Light-curve modeling and mean properties measured from asteroseismology are combined to yield specific measurements of periods, masses, radii, temperatures, eclipse timing variations, core rotation rates, and red giant evolutionary state. After using three different techniques to eliminate false positives, out of the 70 systems common to the red giant and eclipsing-binary catalogs we find 13 strong candidates (12 previously unknown) to be eclipsing binaries, one to be a non-eclipsing binary with tidally induced oscillations, and 10 more to be hierarchical triple systems, all of which include a pulsating red giant. The systems span a range of orbital eccentricities, periods, and spectral types F, G, K, and M for the companion of the red giant. One case even suggests an eclipsing binary composed of two red giant stars and another of a red giant with a δ-Scuti star. The discovery of multiple pulsating red giants in eclipsing binaries provides an exciting test bed for precise astrophysical modeling, and follow-up spectroscopic observations of many of the

THE NEW ECLIPSING CV MASTER OTJ192328.22+612413.5—A POSSIBLE SW SEXTANTIS STAR

International Nuclear Information System (INIS)

Kennedy, M. R.; Callanan, P.; Bouanane, S.; Garnavich, P. M.; Rose, B. M.; Szkody, P.; Bendjoya, P.; Abe, L.; Rivet, J. P.; Suarez, O.

2016-01-01

We present optical photometry and spectroscopy of the new eclipsing cataclysmic variable MASTER OTJ192328.22+612413.5, discovered by the MASTER team. We find the orbital period to be P = 0.16764612(5) day/4.023507(1) hr. The depth of the eclipse (2.9 ± 0.1 mag) suggests that the system is nearly edge on, and modeling of the system confirms the inclination to be between 81.°3 and 83.°6. The brightness outside the eclipse varies between observations, with a change of 1.6 ± 0.1 mag. Spectroscopy reveals double-peaked Balmer emission lines. By using spectral features matching a late M-type companion, we bound the distance to be 750 ± 250 pc, depending on the companion’s spectral type. The source displays 2 mag brightness changes on timescales of days. The amplitude of these changes, along with the spectrum at the faint state, suggest that the system is possibly a dwarf nova. The lack of any high-excitation He ii lines suggests that this system is not magnetically dominated. The light curve in both quiescence and outburst resembles that of Lanning 386, implying MASTER OTJ192328.22+612413.5 is a possible cross between a dwarf nova and a SW Sextantis star.

THE NEW ECLIPSING CV MASTER OTJ192328.22+612413.5—A POSSIBLE SW SEXTANTIS STAR

Energy Technology Data Exchange (ETDEWEB)

Kennedy, M. R.; Callanan, P.; Bouanane, S. [Department of Physics, University College Cork, Cork (Ireland); Garnavich, P. M.; Rose, B. M. [Department of Physics, University of Notre Dame, Notre Dame, IN 46556 (United States); Szkody, P. [Department of Astronomy, University of Washington, Seattle, WA (United States); Bendjoya, P.; Abe, L.; Rivet, J. P.; Suarez, O., E-mail: markkennedy@umail.ucc.ie [Laboratoire Lagrange UMR 7293, Université de Nice Sophia-Antipolis, Observatoire de la Côte d’Azur (France)

2016-07-01

We present optical photometry and spectroscopy of the new eclipsing cataclysmic variable MASTER OTJ192328.22+612413.5, discovered by the MASTER team. We find the orbital period to be P = 0.16764612(5) day/4.023507(1) hr. The depth of the eclipse (2.9 ± 0.1 mag) suggests that the system is nearly edge on, and modeling of the system confirms the inclination to be between 81.°3 and 83.°6. The brightness outside the eclipse varies between observations, with a change of 1.6 ± 0.1 mag. Spectroscopy reveals double-peaked Balmer emission lines. By using spectral features matching a late M-type companion, we bound the distance to be 750 ± 250 pc, depending on the companion’s spectral type. The source displays 2 mag brightness changes on timescales of days. The amplitude of these changes, along with the spectrum at the faint state, suggest that the system is possibly a dwarf nova. The lack of any high-excitation He ii lines suggests that this system is not magnetically dominated. The light curve in both quiescence and outburst resembles that of Lanning 386, implying MASTER OTJ192328.22+612413.5 is a possible cross between a dwarf nova and a SW Sextantis star.

Light curves for ''bump Cepheids'' computed with a dynamically zoned pulsation code

International Nuclear Information System (INIS)

Adams, T.F.; Castor, J.E.; Davis, C.G.

1978-01-01

The dynamically zoned pulsation code developed by Castor, Davis, and Davison has been used to recalculate the Goddard model and to calculate three other Cepheid models with the same period (9.8 days). This family of models shows how the bumps and other features of the light and velocity curves change as the mass is varied at constant period. This study, with a code that is capable of producing reliable light curves, shows again that the light and velocity curves for 9.8-day Cepheid models with standard homogeneous compositions do not show bumps like those that are observed unless the mass is significantly lower than the ''evolutionary mass.'' The light and velocity curves for the Goddard model presented here are similar to those computed independently by Fischel, Sparks, and Karp. They should be useful as standards for future investigators

Early light curves for Type Ia supernova explosion models

Science.gov (United States)

Noebauer, U. M.; Kromer, M.; Taubenberger, S.; Baklanov, P.; Blinnikov, S.; Sorokina, E.; Hillebrandt, W.

2017-12-01

Upcoming high-cadence transient survey programmes will produce a wealth of observational data for Type Ia supernovae. These data sets will contain numerous events detected very early in their evolution, shortly after explosion. Here, we present synthetic light curves, calculated with the radiation hydrodynamical approach STELLA for a number of different explosion models, specifically focusing on these first few days after explosion. We show that overall the early light curve evolution is similar for most of the investigated models. Characteristic imprints are induced by radioactive material located close to the surface. However, these are very similar to the signatures expected from ejecta-CSM or ejecta-companion interaction. Apart from the pure deflagration explosion models, none of our synthetic light curves exhibit the commonly assumed power-law rise. We demonstrate that this can lead to substantial errors in the determination of the time of explosion. In summary, we illustrate with our calculations that even with very early data an identification of specific explosion scenarios is challenging, if only photometric observations are available.

A COMPREHENSIVE ANALYSIS OF SWIFT/X-RAY TELESCOPE DATA. IV. SINGLE POWER-LAW DECAYING LIGHT CURVES VERSUS CANONICAL LIGHT CURVES AND IMPLICATIONS FOR A UNIFIED ORIGIN OF X-RAYS

International Nuclear Information System (INIS)

Liang Enwei; Lue Houjun; Hou Shujin; Zhang Binbin; Zhang Bing

2009-01-01

By systematically analyzing the Swift/XRT light curves detected before 2009 July, we find 19 light curves that monotonously decay as a single power law (SPL) with an index of 1 ∼ 1.7 from tens (or hundreds) of seconds to ∼10 5 s post the gamma-ray burst (GRB) trigger. They are apparently different from the canonical light curves characterized by a shallow-to-normal decay transition. We compare the observations of the prompt gamma rays and the X-rays for these two samples of GRBs (SPL vs. canonical). No statistical difference is found in the prompt gamma-ray properties for the two samples. The X-ray properties of the two samples are also similar, although the SPL sample tends to have a slightly lower neutral hydrogen absorption column for the host galaxies and a slightly larger energy release compared with the canonical sample. The SPL X-ray Telescope (XRT) light curves in the burst frame gradually merge into a conflux, and their luminosities at 10 5 s are normally distributed at log L/ergs s -1 = 45.6 ± 0.5. The normal decay segment of the canonical XRT light curves has the same feature. Similar to the normal decay segment, the SPL light curves satisfy the closure relations and therefore can be roughly explained with external shock models. In the scenario that the X-rays are the afterglows of the GRB fireball, our results indicate that the shallow decay would be due to energy injection into the fireball and the total energy budget after injection for both samples of GRBs is comparable. More intriguing, we find that a prior X-ray emission model proposed by Yamazaki is more straightforward to interpret the observed XRT data. We show that the zero times (T 0 ) of the X-rays are 10 2 -10 5 s prior to the GRB trigger for the canonical sample, and satisfy a log-normal distribution. The negligible T 0 's of the SPL sample are consistent with being the tail of T 0 distributions at low end, suggesting that the SPL sample and the canonical sample may be from a same

Generalized Fermat's principle and action for light rays in a curved spacetime

Science.gov (United States)

Frolov, Valeri P.

2013-09-01

We start with formulation of the generalized Fermat’s principle for light propagation in a curved spacetime. We apply Pontryagin’s minimum principle of the optimal control theory and obtain an effective Hamiltonian for null geodesics in a curved spacetime. We explicitly demonstrate that dynamical equations for this Hamiltonian correctly reproduce null geodesic equations. Other forms of the action for light rays in a curved spacetime are also discussed.

Characterization of Type Ia Supernova Light Curves Using Principal Component Analysis of Sparse Functional Data

Science.gov (United States)

He, Shiyuan; Wang, Lifan; Huang, Jianhua Z.

2018-04-01

With growing data from ongoing and future supernova surveys, it is possible to empirically quantify the shapes of SNIa light curves in more detail, and to quantitatively relate the shape parameters with the intrinsic properties of SNIa. Building such relationships is critical in controlling systematic errors associated with supernova cosmology. Based on a collection of well-observed SNIa samples accumulated in the past years, we construct an empirical SNIa light curve model using a statistical method called the functional principal component analysis (FPCA) for sparse and irregularly sampled functional data. Using this method, the entire light curve of an SNIa is represented by a linear combination of principal component functions, and the SNIa is represented by a few numbers called “principal component scores.” These scores are used to establish relations between light curve shapes and physical quantities such as intrinsic color, interstellar dust reddening, spectral line strength, and spectral classes. These relations allow for descriptions of some critical physical quantities based purely on light curve shape parameters. Our study shows that some important spectral feature information is being encoded in the broad band light curves; for instance, we find that the light curve shapes are correlated with the velocity and velocity gradient of the Si II λ6355 line. This is important for supernova surveys (e.g., LSST and WFIRST). Moreover, the FPCA light curve model is used to construct the entire light curve shape, which in turn is used in a functional linear form to adjust intrinsic luminosity when fitting distance models.

Devil in the Details: Investigating Astrophysical Phenomena with Kepler Light Curves

Science.gov (United States)

Jenkins, Jon Michael; SOC, Kepler; SO, Kepler; Kepler Science Team

2011-05-01

The light curves produced by the Kepler photometer are unprecedented in their photometric precision, completeness, and contiguity. Moreover, although Kepler was designed to detect 100 ppm changes in brightness corresponding to transits of Earth-size planets crossing Sun-size stars, the Kepler light curves preserve intrinsic intensity variations across a large dynamic range, including those of RR Lyrae stars, which can increase their brightness by more than a factor of two over a few hours. The large dynamic range and phenomenal photometric precision of Kepler promises to revolutionize the study of intrinsic stellar variability and a wide variety of variable stars on timescales from minutes to several years. In this paper, we describe the science pipeline processing that produces the uncorrected and the systematic error-corrected light curves, and give examples of residual instrumental artifacts that can be found in the data, such as those caused by thermal changes due to the position of the spacecraft with relation to the sun or heaters cycling on and off on various spacecraft components (which can change the shape of the telescope and alter its focus), as well as examples of processing artifacts that can occur. We also describe algorithms in development that promise to improve our ability to identify and remove instrumental signatures and further reduce the incidence of processing artifacts in the archival light curves, thereby increasing the usability of the corrected light curves for astrophysical investigations. Kepler was selected as the 10th mission of the Discovery Program. Funding for this mission is provided by the NASA Science Mission Directorate.

Light and velocity curve bumps for BW Vulpeculae

International Nuclear Information System (INIS)

Pesnell, W.D.; Cox, A.N.

1980-01-01

Bumps in the light and radial velocity curves of the Beta Cephei star BW Vulpeculae were modeled. Two mechanisms, a resonance phenomena and non-linear pulsations, were investigated. The resonance condition was clearly not fulfilled, the calculated period ratio being approximately 0.60, where a value of 0.50 L +- 0.03 is required for resonance. In the non-linear calculation, the bump appears, with the correct phase, but was found at an amplitude that is too large. Further, the light curve does not show any bump-like feature. The cause of the bump is the large spurious boost given the star's velocity field by the solution methods. The calculated periods of the stellar models are shorter than those of previous calculations, enhancing the possibility that these stars pulsate in a radial fundamental mode

LUT REVEALS AN ALGOL-TYPE ECLIPSING BINARY WITH THREE ADDITIONAL STELLAR COMPANIONS IN A MULTIPLE SYSTEM

Energy Technology Data Exchange (ETDEWEB)

Zhu, L.-Y.; Zhou, X.; Qian, S.-B.; Li, L.-J.; Liao, W.-P.; Tian, X.-M.; Wang, Z.-H. [Yunnan Observatories, Chinese Academy of Sciences (CAS), P.O. Box 110, 650011 Kunming (China); Hu, J.-Y., E-mail: zhuly@ynao.ac.cn [National Astronomical Observatories, Chinese Academy of Sciences, 100012 Beijing (China)

2016-04-15

A complete light curve of the neglected eclipsing binary Algol V548 Cygni in the UV band was obtained with the Lunar-based Ultraviolet Telescope in 2014 May. Photometric solutions are obtained using the Wilson–Devinney method. It is found that solutions with and without third light are quite different. The mass ratio without third light is determined to be q = 0.307, while that derived with third light is q = 0.606. It is shown that V548 Cygni is a semi-detached binary where the secondary component is filling the critical Roche lobe. An analysis of all available eclipse times suggests that there are three cyclic variations in the O–C diagram that are interpreted by the light travel-time effect via the presence of three additional stellar companions. This is in agreement with the presence of a large quantity of third light in the system. The masses of these companions are estimated as m sin i′ ∼ 1.09, 0.20, and 0.52 M{sub ⊙}. They are orbiting the central binary with orbital periods of about 5.5, 23.3, and 69.9 years, i.e., in 1:4:12 resonance orbit. Their orbital separations are about 4.5, 13.2, and 26.4 au, respectively. Our photometric solutions suggest that they contribute about 32.4% to the total light of the multiple system. No obvious long-term changes in the orbital period were found, indicating that the contributions of the mass transfer and the mass loss due to magnetic braking to the period variations are comparable. The detection of three possible additional stellar components orbiting a typical Algol in a multiple system make V548 Cygni a very interesting binary to study in the future.

Mass estimates from optical-light curves for binary X-ray sources

International Nuclear Information System (INIS)

Avni, Y.

1978-01-01

The small amplitude variations with orbital phase of the optical light from X-ray binaries are caused by the changing geometrical aspect of the primary as seen by a fixed observer. The shape and the amplitude of the light curve depends on the stellar masses and on the orbital elements. The light curve can, therefore, be used to determine, or set limits on, the parameters of the binary system. A self-consistent procedure for the calculation of the light curve can be formulated if the primary is formulated if the primary is uniformly rotating at an angular velocity equal to the angular velocity of its orbital revolution in a circular orbit, and if the primary is in a hydrostatic and radiative equilibrium in the co-rotating frame. When the primary is further approximated to be centrally condensed, the above set of assumptions is called the standard picture. The standard picture is described, its validity discussed and its application to various systems reviewed. (C.F.)

Totality eclipses of the Sun

CERN Document Server

Littmann, Mark; Willcox, Ken

2008-01-01

A total eclipse of the Sun is the most awesome sight in the heavens. Totality: Eclipses of the Sun takes you to eclipses of the past, present, and future, and lets you see - and feel - why people travel to the ends of the Earth to observe them. - ;A total eclipse of the Sun is the most awesome sight in the heavens. Totality: Eclipses of the Sun takes you to eclipses of the past, present, and future, and lets you see - and feel - why people travel to the ends of the Earth to observe them. Totality: Eclipses of the Sun is the best guide and reference book on solar eclipses ever written. It explains: how to observe them; how to photograph and videotape them; why they occur; their history and mythology; and future eclipses - when and where to see them. Totality also tells the remarkable story of how eclipses shocked scientists, revealed the workings of the Sun, and made Einstein famous. And the book shares the experiences and advice of many veteran eclipse observers. Totality: Eclipses of the Sun is profusely ill...

NEPTUNE'S DYNAMIC ATMOSPHERE FROM KEPLER K2 OBSERVATIONS: IMPLICATIONS FOR BROWN DWARF LIGHT CURVE ANALYSES.

Science.gov (United States)

Simon, Amy A; Rowe, Jason F; Gaulme, Patrick; Hammel, Heidi B; Casewell, Sarah L; Fortney, Jonathan J; Gizis, John E; Lissauer, Jack J; Morales-Juberias, Raul; Orton, Glenn S; Wong, Michael H; Marley, Mark S

2016-02-01

Observations of Neptune with the Kepler Space Telescope yield a 49 day light curve with 98% coverage at a 1 minute cadence. A significant signature in the light curve comes from discrete cloud features. We compare results extracted from the light curve data with contemporaneous disk-resolved imaging of Neptune from the Keck 10-m telescope at 1.65 microns and Hubble Space Telescope visible imaging acquired nine months later. This direct comparison validates the feature latitudes assigned to the K2 light curve periods based on Neptune's zonal wind profile, and confirms observed cloud feature variability. Although Neptune's clouds vary in location and intensity on short and long timescales, a single large discrete storm seen in Keck imaging dominates the K2 and Hubble light curves; smaller or fainter clouds likely contribute to short-term brightness variability. The K2 Neptune light curve, in conjunction with our imaging data, provides context for the interpretation of current and future brown dwarf and extrasolar planet variability measurements. In particular we suggest that the balance between large, relatively stable, atmospheric features and smaller, more transient, clouds controls the character of substellar atmospheric variability. Atmospheres dominated by a few large spots may show inherently greater light curve stability than those which exhibit a greater number of smaller features.

Light Curve Simulation Using Spacecraft CAD Models and Empirical Material Spectral BRDFS

Science.gov (United States)

Willison, A.; Bedard, D.

This paper presents a Matlab-based light curve simulation software package that uses computer-aided design (CAD) models of spacecraft and the spectral bidirectional reflectance distribution function (sBRDF) of their homogenous surface materials. It represents the overall optical reflectance of objects as a sBRDF, a spectrometric quantity, obtainable during an optical ground truth experiment. The broadband bidirectional reflectance distribution function (BRDF), the basis of a broadband light curve, is produced by integrating the sBRDF over the optical wavelength range. Colour-filtered BRDFs, the basis of colour-filtered light curves, are produced by first multiplying the sBRDF by colour filters, and integrating the products. The software package's validity is established through comparison of simulated reflectance spectra and broadband light curves with those measured of the CanX-1 Engineering Model (EM) nanosatellite, collected during an optical ground truth experiment. It is currently being extended to simulate light curves of spacecraft in Earth orbit, using spacecraft Two-Line-Element (TLE) sets, yaw/pitch/roll angles, and observer coordinates. Measured light curves of the NEOSSat spacecraft will be used to validate simulated quantities. The sBRDF was chosen to represent material reflectance as it is spectrometric and a function of illumination and observation geometry. Homogeneous material sBRDFs were obtained using a goniospectrometer for a range of illumination and observation geometries, collected in a controlled environment. The materials analyzed include aluminum alloy, two types of triple-junction photovoltaic (TJPV) cell, white paint, and multi-layer insulation (MLI). Interpolation and extrapolation methods were used to determine the sBRDF for all possible illumination and observation geometries not measured in the laboratory, resulting in empirical look-up tables. These look-up tables are referenced when calculating the overall sBRDF of objects, where

PLANETARY CONSTRUCTION ZONES IN OCCULTATION: DISCOVERY OF AN EXTRASOLAR RING SYSTEM TRANSITING A YOUNG SUN-LIKE STAR AND FUTURE PROSPECTS FOR DETECTING ECLIPSES BY CIRCUMSECONDARY AND CIRCUMPLANETARY DISKS

Energy Technology Data Exchange (ETDEWEB)

Mamajek, Eric E.; Quillen, Alice C.; Pecaut, Mark J.; Moolekamp, Fred; Scott, Erin L. [Department of Physics and Astronomy, University of Rochester, Rochester, NY 14627-0171 (United States); Kenworthy, Matthew A. [Leiden Observatory, Leiden University, P.O. Box 9513, 2300 RA Leiden (Netherlands); Cameron, Andrew Collier; Parley, Neil R. [School of Physics and Astronomy, University of St Andrews, North Haugh, St Andrews, Fife KY16 9SS (United Kingdom)

2012-03-15

The large relative sizes of circumstellar and circumplanetary disks imply that they might be seen in eclipse in stellar light curves. We estimate that a survey of {approx}10{sup 4} young ({approx}10 million year old) post-accretion pre-main-sequence stars monitored for {approx}10 years should yield at least a few deep eclipses from circumplanetary disks and disks surrounding low-mass companion stars. We present photometric and spectroscopic data for a pre-main-sequence K5 star (1SWASP J140747.93-394542.6 = ASAS J140748-3945.7), a newly discovered {approx}0.9 M{sub Sun} member of the {approx}16 Myr old Upper Centaurus-Lupus subgroup of Sco-Cen at a kinematic distance of 128 {+-} 13 pc. This star exhibited a remarkably long, deep, and complex eclipse event centered on 2007 April 29 (as discovered in Super Wide Angle Search for Planets (SuperWASP) photometry, and with portions of the dimming confirmed by All Sky Automated Survey (ASAS) data). At least five multi-day dimming events of >0.5 mag are identified, with a >3.3 mag deep eclipse bracketed by two pairs of {approx}1 mag eclipses symmetrically occurring {+-}12 days and {+-}26 days before and after. Hence, significant dimming of the star was taking place on and off over at least a {approx}54 day period in 2007, and a strong >1 mag dimming event occurring over a {approx}12 day span. We place a firm lower limit on the period of 850 days (i.e., the orbital radius of the eclipser must be >1.7 AU and orbital velocity must be <22 km s{sup -1}). The shape of the light curve is similar to the lopsided eclipses of the Be star EE Cep. We suspect that this new star is being eclipsed by a low-mass object orbited by a dense inner disk, further girded by at least three dusty rings of optical depths near unity. Between these rings are at least two annuli of near-zero optical depth (i.e., gaps), possibly cleared out by planets or moons, depending on the nature of the secondary. For possible periods in the range 2.33-200 yr, the

Using Light Curves to Characterize Size and Shape of Pseudo-Debris

Science.gov (United States)

Rodriquez, Heather M.; Abercromby, Kira J.; Jarvis, Kandy S.; Barker, Edwin

2006-01-01

Photometric measurements were collected for a new study aimed at estimating orbital debris sizes based on object brightness. To obtain a size from optical measurements the current practice is to assume an albedo and use a normalized magnitude to calculate optical size. However, assuming a single albedo value may not be valid for all objects or orbit types; material type and orientation can mask an object s true optical cross section. This experiment used a CCD camera to record data, a 300 W Xenon, Ozone Free collimated light source to simulate solar illumination, and a robotic arm with five degrees of freedom to move the piece of simulated debris through various orientations. The pseudo-debris pieces used in this experiment originate from the European Space Operations Centre s ESOC2 ground test explosion of a mock satellite. A uniformly illuminated white ping-pong ball was used as a zero-magnitude reference. Each debris piece was then moved through specific orientations and rotations to generate a light curve. This paper discusses the results of five different object-based light curves as measured through an x-rotation. Intensity measurements, from which each light curve was generated, were recorded in five degree increments from zero to 180 degrees. Comparing light curves of different shaped and sized pieces against their characteristic length establishes the start of a database from which an optical size estimation model will be derived in the future.

X-ray heating and the optical light curve of HZ Herculis

International Nuclear Information System (INIS)

Perrenod, S.C.; Shields, G.A.

1975-01-01

We discuss theoretically the optical light curve of HZ Her, the binary companion of the pulsed X-ray source Her X-1. Using model stellar atmospheres, we construct light curves that are in agreement with UBV photometry of HZ Her except for the sharpness of the minimum. Unlike previous authors, we find that heating of the photosphere of HZ Her by the observed X-ray flux is sufficient to explain the amplitude of the light variations in each color, if the X-ray emission persists at HZ Her throughout the 35-day ON-OFF CYCLE. We rule out a corona surrounding HZ Her as the source of the extra light near minimum, and we also rule out a model wherein the extra light is caused by a stellar wind that electron-scatters optical light emitted by the photosphere of the hot side of the star

UBV Photometry at the Outside Eclipse Phase of AZ Cassiopeiae

Directory of Open Access Journals (Sweden)

Il-Seong Nha

1994-06-01

Full Text Available VV Cep-type long period spectroscopic-eclipsing binary AZ Cas has been observed for five years, 1985 Oct ~ 1990 Feb, in UBV at the Ilsan Station of Yonsei University Observatory. A total of 431 observations (U=129, B=142 and V=160 are made for 86 nights. Instrumental differential UBV and B-V light curves made with these observations cover phases nearly a half of one period. There is no appreciable light variation in V but in other two passbands a gradual decrease of the brightness is clearly noticed. The loss of light in B resulted in a reddening in △(B-V by +0.06 at phases between 0.4~0.5 as compared with that of at phase ~0.1. This intrinsic reddening arouses a question why at the orbital phase of the transit of a hot star in front of a cool M supergiant the heating of the facing hemisphere of M supergiant by the strong radiation from the B star is absent. With regard to this unusual situation we propose a hypothesis that a large amount of gas stream of low temperature ejected from the surface of M supergiant component towards the B star dominates the brightness of B star and reflection effect.

Light equation in eclipsing binary CV Boo: third body candidate in elliptical orbit

Science.gov (United States)

Bogomazov, A. I.; Kozyreva, V. S.; Satovskii, B. L.; Krushevska, V. N.; Kuznyetsova, Y. G.; Ehgamberdiev, S. A.; Karimov, R. G.; Khalikova, A. V.; Ibrahimov, M. A.; Irsmambetova, T. R.; Tutukov, A. V.

2016-12-01

A short period eclipsing binary star CV Boo is tested for the possible existence of additional bodies in the system with a help of the light equation method. We use data on the moments of minima from the literature as well as from our observations during 2014 May-July. A variation of the CV Boo's orbital period is found with a period of {≈}75 d. This variation can be explained by the influence of a third star with a mass of {≈}0.4 M_{⊙} in an eccentric orbit with e≈0.9. A possibility that the orbital period changes on long time scales is discussed. The suggested tertiary companion is near the chaotic zone around the central binary, so CV Boo represents an interesting example to test its dynamical evolution. A list of 14 minima moments of the binary obtained from our observations is presented.

EXPLORING THE POTENTIAL DIVERSITY OF EARLY TYPE IA SUPERNOVA LIGHT CURVES

Energy Technology Data Exchange (ETDEWEB)

Piro, Anthony L. [Carnegie Observatories, 813 Santa Barbara Street, Pasadena, CA 91101 (United States); Morozova, Viktoriya S., E-mail: piro@obs.carnegiescience.edu [Theoretical Astrophysics, California Institute of Technology, 1200 E California Boulevard, M/C 350-17, Pasadena, CA 91125 (United States)

2016-07-20

During the first several days after explosion, Type Ia supernova light curves probe the outer layers of the exploding star, and therefore provide important clues for identifying their progenitors. We investigate how both the shallow {sup 56}Ni distribution and the presence of circumstellar material shape these early light curves. This is performed using a series of numerical experiments with parameterized properties for systematic exploration. Although not all of the considered models may be realized in nature (and indeed there are arguments why some of them should not occur), the spirit of this work is to provide a broader exploration of the diversity of possibilities. We find that shallower {sup 56}Ni leads to steeper, bluer light curves. Differences in the shape of the rise can introduce errors in estimating the explosion time, and thus impact efforts to infer upper limits on the progenitor or companion radius from a lack of observed shock cooling emission. Circumstellar material can lead to significant luminosity during the first few days, but its presence can be difficult to identify depending on the degree of nickel mixing. In some cases, the hot emission of circumstellar material may even lead to a signature similar to an interaction with a companion, and thus in the future additional diagnostics should be gathered for properly assessing early light curves.

Optical eclipses and precessional effects in the X-ray binary system HD 77581=4U 0900-40

International Nuclear Information System (INIS)

Khruzina, T.S.; Cherepashchuk, A.M.

1982-01-01

The longperiod (P=93.3sup(d)) variability of the amplitude and shape of the optical light curves of the X-ray binary HD 77581 has been discovered from the analysis of all published photometric data. The 93.3-day period is presumably the period of the forced precession of the rotational axis of the optical star. It is shown that the system HD 77581 appears to be an eclipsing binary in the optical range with the amplitude of the ellipsoidal variability approximately 0sup(m).04 and the depth of the eclipse reaching approximately 0sup(m).04. The eclipses are caused by the gaseous streams and the accreting structure, the orientation of which in the binary system is varying with the precession period of the optical star. The estimates of the parameters of the system are obtained. It is shown that the parameter of the Roche Lobe filling for the optical star is μ < 1. The mass of the neutron star is Msub(x)=(1.6+-0.3) Msub(Sun), where Msub(Sun) is the solar mass. The forced precession of the optical star is connected with the non-perpendicularity of its rotational axis to the orbit plane of the binary system. This non-perpendicularity may be a result of supernova explosion in a close binary system

Chandra Sees Remarkable Eclipse of Black Hole

Science.gov (United States)

2007-04-01

A remarkable eclipse of a supermassive black hole and the hot gas disk around it has been observed with NASA's Chandra X-ray Observatory. This eclipse has allowed two key predictions about the effects of supermassive black holes to be tested. Just as eclipses of the Sun and moon give astronomers rare opportunities to learn about those objects, an alignment in a nearby galaxy has provided a rare opportunity to investigate a supermassive black hole. Illustrations of Black Hole Eclipse Illustrations of Black Hole Eclipse The supermassive black hole is located in NGC 1365, a galaxy 60 million light years from Earth. It contains a so called active galactic nucleus, or AGN. Scientists believe that the black hole at the center of the AGN is fed by a steady stream of material, presumably in the form of a disk. Material just about to fall into a black hole should be heated to millions of degrees before passing over the event horizon, or point of no return. The disk of gas around the central black hole in NGC 1365 produces copious X-rays but is much too small to resolve directly with a telescope. However, the disk was eclipsed by an intervening cloud, so observation of the time taken for the disk to go in and out of eclipse allowed scientists to estimate the size of the disk. Black Hole Animation Black Hole Animation "For years we've been struggling to confirm the size of this X-ray structure," said Guido Risaliti of the Harvard-Smithsonian Center for Astrophysics (CfA) in Cambridge, Mass, and the Italian Institute of Astronomy (INAF). "This serendipitous eclipse enabled us to make this breakthrough." The Chandra team directly measured the size of the X-ray source as about seven times the distance between the Sun and the Earth. That means the source of X-rays is about 2 billion times smaller than the host galaxy and only about 10 times larger than the estimated size of the black hole's event horizon, consistent with theoretical predictions. Chandra X-ray Image of NGC 1365

UBVRc Ic ANALYSIS OF THE RECENTLY DISCOVERED TOTALLY ECLIPSING EXTREME MASS RATIO BINARY V1853 ORIONIS, AND A STATISTICAL LOOK AT 25 OTHER EXTREME MASS RATIO SOLAR-TYPE CONTACT BINARIES

International Nuclear Information System (INIS)

Samec, R. G.; Labadorf, C. M.; Hawkins, N. C.; Faulkner, D. R.; Van Hamme, W.

2011-01-01

We present precision CCD light curves, a period study, photometrically derived standard magnitudes, and a five-color simultaneous Wilson code solution of the totally eclipsing, yet shallow amplitude (A v ∼ 0.4 mag) eclipsing, binary V1853 Orionis. It is determined to be an extreme mass ratio, q = 0.20, W-type W UMa overcontact binary. From our standard star observations, we find that the variable is a late-type F spectral-type dwarf, with a secondary component of about 0.24 solar masses (stellar type M5V). Its long eclipse duration (41 minutes) as compared to its period, 0.383 days, attests to the small relative size of the secondary. Furthermore, it has reached a Roche lobe fill-out of ∼50% of its outer critical lobe as it approaches its final stages of binary star evolution, that of a fast spinning single star. Finally, a summary of about 25 extreme mass ratio solar-type binaries is given.

PAIR INSTABILITY SUPERNOVAE: LIGHT CURVES, SPECTRA, AND SHOCK BREAKOUT

International Nuclear Information System (INIS)

Kasen, Daniel; Woosley, S. E.; Heger, Alexander

2011-01-01

For the initial mass range (140 M sun sun ) stars die in a thermonuclear runaway triggered by the pair-production instability. The supernovae they make can be remarkably energetic (up to ∼10 53 erg) and synthesize considerable amounts of radioactive isotopes. Here we model the evolution, explosion, and observational signatures of representative pair instability supernovae (PI SNe) spanning a range of initial masses and envelope structures. The predicted light curves last for hundreds of days and range in luminosity from very dim to extremely bright (L ∼ 10 44 erg s -1 ). The most massive events are bright enough to be seen at high redshift, but the extended light curve duration (∼1 yr)-prolonged by cosmological time-dilation-may make it difficult to detect them as transients. A more promising approach may be to search for the brief and luminous outbreak occurring when the explosion shock wave first reaches the stellar surface. Using a multi-wavelength radiation-hydrodynamics code we calculate that, in the rest frame, the shock breakout transients of PI SNe reach luminosities of 10 45 -10 46 erg s -1 , peak at wavelengths ∼30-170 A, and last for several hours. We discuss how observations of the light curves, spectra, and breakout emission can be used to constrain the mass, radius, and metallicity of the progenitor.

New limb-darkening coefficients for modeling binary star light curves

Science.gov (United States)

Van Hamme, W.

1993-01-01

We present monochromatic, passband-specific, and bolometric limb-darkening coefficients for a linear as well as nonlinear logarithmic and square root limb-darkening laws. These coefficients, including the bolometric ones, are needed when modeling binary star light curves with the latest version of the Wilson-Devinney light curve progam. We base our calculations on the most recent ATLAS stellar atmosphere models for solar chemical composition stars with a wide range of effective temperatures and surface gravitites. We examine how well various limb-darkening approximations represent the variation of the emerging specific intensity across a stellar surface as computed according to the model. For binary star light curve modeling purposes, we propose the use of a logarithmic or a square root law. We design our tables in such a manner that the relative quality of either law with respect to another can be easily compared. Since the computation of bolometric limb-darkening coefficients first requires monochromatic coefficients, we also offer tables of these coefficients (at 1221 wavelength values between 9.09 nm and 160 micrometer) and tables of passband-specific coefficients for commonly used photometric filters.

Estimation of error on the cross-correlation, phase and time lag between evenly sampled light curves

Science.gov (United States)

Misra, R.; Bora, A.; Dewangan, G.

2018-04-01

Temporal analysis of radiation from Astrophysical sources like Active Galactic Nuclei, X-ray Binaries and Gamma-ray bursts provides information on the geometry and sizes of the emitting regions. Establishing that two light-curves in different energy bands are correlated, and measuring the phase and time-lag between them is an important and frequently used temporal diagnostic. Generally the estimates are done by dividing the light-curves into large number of adjacent intervals to find the variance or by using numerically expensive simulations. In this work we have presented alternative expressions for estimate of the errors on the cross-correlation, phase and time-lag between two shorter light-curves when they cannot be divided into segments. Thus the estimates presented here allow for analysis of light-curves with relatively small number of points, as well as to obtain information on the longest time-scales available. The expressions have been tested using 200 light curves simulated from both white and 1 / f stochastic processes with measurement errors. We also present an application to the XMM-Newton light-curves of the Active Galactic Nucleus, Akn 564. The example shows that the estimates presented here allow for analysis of light-curves with relatively small (∼ 1000) number of points.

Average Albedos of Close-in Super-Earths and Super-Neptunes from Statistical Analysis of Long-cadence Kepler Secondary Eclipse Data

Science.gov (United States)

Sheets, Holly A.; Deming, Drake

2017-10-01

We present the results of our work to determine the average albedo for small, close-in planets in the Kepler candidate catalog. We have adapted our method of averaging short-cadence light curves of multiple Kepler planet candidates to long-cadence data, in order to detect an average albedo for the group of candidates. Long-cadence data exist for many more candidates than the short-cadence data, and so we separate the candidates into smaller radius bins than in our previous work: 1-2 {R}\\oplus , 2-4 {R}\\oplus , and 4-6 {R}\\oplus . We find that, on average, all three groups appear darker than suggested by the short-cadence results, but not as dark as many hot Jupiters. The average geometric albedos for the three groups are 0.11 ± 0.06, 0.05 ± 0.04, and 0.23 ± 0.11, respectively, for the case where heat is uniformly distributed about the planet. If heat redistribution is inefficient, the albedos are even lower, since there will be a greater thermal contribution to the total light from the planet. We confirm that newly identified false-positive Kepler Object of Interest (KOI) 1662.01 is indeed an eclipsing binary at twice the period listed in the planet candidate catalog. We also newly identify planet candidate KOI 4351.01 as an eclipsing binary, and we report a secondary eclipse measurement for Kepler-4b (KOI 7.01) of ˜7.50 ppm at a phase of ˜0.7, indicating that the planet is on an eccentric orbit.

Exquisite Nova Light Curves from the Solar Mass Ejection Imager (SMEI)

Science.gov (United States)

Hounsell, R.; Bode, M. F.; Hick, P. P.; Buffington, A.; Jackson, B. V.; Clover, J. M.; Shafter, A. W.; Darnley, M. J.; Mawson, N. R.; Steele, I. A.; Evans, A.; Eyres, S. P. S.; O'Brien, T. J.

2010-11-01

We present light curves of three classical novae (CNe; KT Eridani, V598 Puppis, V1280 Scorpii) and one recurrent nova (RS Ophiuchi) derived from data obtained by the Solar Mass Ejection Imager (SMEI) on board the Coriolis satellite. SMEI provides near complete skymap coverage with precision visible-light photometry at 102 minute cadence. The light curves derived from these skymaps offer unprecedented temporal resolution around, and especially before, maximum light, a phase of the eruption normally not covered by ground-based observations. They allow us to explore fundamental parameters of individual objects including the epoch of the initial explosion, the reality and duration of any pre-maximum halt (found in all three fast novae in our sample), the presence of secondary maxima, speed of decline of the initial light curve, plus precise timing of the onset of dust formation (in V1280 Sco) leading to estimation of the bolometric luminosity, white dwarf mass, and object distance. For KT Eri, Liverpool Telescope SkyCamT data confirm important features of the SMEI light curve and overall our results add weight to the proposed similarities of this object to recurrent rather than to CNe. In RS Oph, comparison with hard X-ray data from the 2006 outburst implies that the onset of the outburst coincides with extensive high-velocity mass loss. It is also noted that two of the four novae we have detected (V598 Pup and KT Eri) were only discovered by ground-based observers weeks or months after maximum light, yet these novae reached peak magnitudes of 3.46 and 5.42, respectively. This emphasizes the fact that many bright novae per year are still overlooked, particularly those of the very fast speed class. Coupled with its ability to observe novae in detail even when relatively close to the Sun in the sky, we estimate that as many as five novae per year may be detectable by SMEI.

Light curve analysis of the late type binary V523 Cassiopeiae

Directory of Open Access Journals (Sweden)

Latković O.

2009-01-01

Full Text Available We present the analysis of V and R light curves of the late type contact binary V523 Cas for the season of 2006. These observations make part of the monitoring program aimed at studying the long-term light curve variability in this system. Our results confirm that the system is in an over contact configuration, and include a bright spot in the neck region of the cooler and larger primary. We compare these results with the previous solution, obtained for the season 2005 dataset and discuss the differences.

Photometry of the three eclipsing novalike variables EC 21178-5417, GS Pav and V345 Pav

Science.gov (United States)

Bruch, Albert

2017-10-01

As part of a project to better characterize comparatively bright, yet little studied cataclysmic variables time resolved photometry of the three eclipsing novalike variables EC 21178-5417, GS Pav und V345 Pav is presented. Previously known orbital periods are significantly improved and long-term ephemeris are derived. Variations of eclipse profiles, occurring on time scales of days to weeks, are analyzed. Out of eclipse the light curves are characterized by low scale flickering superposed on more gradual variations with amplitudes limited to a few tenths of a magnitude and profiles which at least in EC 21178-5417 and GS Pav roughly follow the same pattern in all observed cycles. Additionally, signs for variations on the time scale of some tens of minutes are seen in GS Pav, most clearly in two subsequent nights when in the first of these a signal with a period of 15.7 min was observed over several hours. In the second night variations with twice this period were seen. While no additional insight could be gained on quasi periodic oscillations (QPOs) and dwarf nova oscillations in EC 21178-5417, previously detected by Warner et al. (2003), and while such oscillations could not be found in V345 Pav, stacked power spectra of GS Pav clearly reveal the presence of QPOs over time intervals of several hours with periods varying between 200 s and 500 s in that system.

Eclipse Soundscapes Project: Making the August 21, 2017 Total Solar Eclipse Accessible to Everyone

Science.gov (United States)

Winter, H. D., III

2017-12-01

The Eclipse Soundscapes Project delivered a multisensory experience that allowed the blind and visually impaired to engage with the August 21, 2017 total solar eclipse along with their sighted peers in a way that would not have been possible otherwise. The project, from the Smithsonian Astrophysical Observatory and NASA's Heliophysics Education Consortium, includes illustrative audio descriptions of the eclipse in real time, recordings of the changing environmental sounds during the eclipse, and an interactive "rumble map" app that allows users to experience the eclipse through touch and sound. The Eclipse Soundscapes Project is working with organizations such as the National Parks Service (NPS), Science Friday, and Brigham Young University and by WGBH's National Center for Accessible Media (NCAM) to bring the awe and wonder of the total solar eclipse and other astronomical phenomena to a segment of the population that has been excluded from and astronomy and astrophysics for far too long, while engaging all learners in new and exciting ways.

SUPERLUMINOUS SUPERNOVAE POWERED BY MAGNETARS: LATE-TIME LIGHT CURVES AND HARD EMISSION LEAKAGE

International Nuclear Information System (INIS)

Wang, S. Q.; Wang, L. J.; Dai, Z. G.; Wu, X. F.

2015-01-01

Recently, research performed by two groups has revealed that the magnetar spin-down energy injection model with full energy trapping can explain the early-time light curves of SN 2010gx, SN 2013dg, LSQ12dlf, SSS120810, and CSS121015 but fails to fit the late-time light curves of these superluminous supernovae (SLSNe). These results imply that the original magnetar-powered model is challenged in explaining these SLSNe. Our paper aims to simultaneously explain both the early- and late-time data/upper limits by considering the leakage of hard emissions. We incorporate quantitatively the leakage effect into the original magnetar-powered model and derive a new semianalytical equation. Comparing the light curves reproduced by our revised magnetar-powered model with the observed data and/or upper limits of these five SLSNe, we found that the late-time light curves reproduced by our semianalytical equation are in good agreement with the late-time observed data and/or upper limits of SN 2010gx, CSS121015, SN 2013dg, and LSQ12dlf and the late-time excess of SSS120810, indicating that the magnetar-powered model might be responsible for these SLSNe and that the gamma-ray and X-ray leakages are unavoidable when the hard photons were down-Comptonized to softer photons. To determine the details of the leakage effect and unveil the nature of SLSNe, more high-quality bolometric light curves and spectra of SLSNe are required

NEWS: Eclipse matters (still)!

Science.gov (United States)

1999-05-01

This collection of snippets has as its theme the 1999 Solar Eclipse, and covers items that might be of interest to eclipse watchers and their associates. Much information can be obtained from the national web site at http://www.eclipse.org.uk. Set up by the CLRC Rutherford Appleton Laboratory, on behalf of the UK Eclipse Group, the site is intended to keep viewers abreast of developments during the countdown to the eclipse. The list of contents includes: about eclipses; eclipse pictures; eclipse science; safety advice; latest news; and local information. There is also a wealth of images and video footage, so the site has been organized with the visitor having a small PC and modem in mind, so that the key information can be accessed as quickly as possible. Free colour leaflets containing useful details for eclipse watchers can be obtained from the Particle Physics and Astronomy Research Council. `The Sun - our local star' and `Neutrinos' are additions to PPARC's series introducing key areas of its science. They answer such questions as what the Sun is, what eclipses are, why the Sun is important and where neutrinos come from. They support the National Curriculum Key Stages 3 and 4 plus A-level physics. The A5 leaflets open out into an A2 sized double-sided wall chart and bulk quantitites are available for class sets, visitor centres, exhibitions, open days etc. A full list of PPARC materials can be found at the website http://www.pparc.ac.uk or by order from Mark Wells, PPARC, Polaris House, North Star Avenue, Swindon SN2 1SZ (fax: 01793 442002). A message has been received from George Care, Head of Physics in the Science Department at Mounts Bay School, Penzance, which we now pass on to our readers. During his application for electronic access to Physics Education via the Institute of Physics Affiliated Schools and Colleges scheme, George notes that his school is on the track of the eclipse this summer and he has invited us to pass on the details to anyone who

The Effect of Starspots on Accurate Radius Determination of the Low-Mass Double-Lined Eclipsing Binary Gu Boo

Science.gov (United States)

Windmiller, G.; Orosz, J. A.; Etzel, P. B.

2010-04-01

GU Boo is one of only a relatively small number of well-studied double-lined eclipsing binaries that contain low-mass stars. López-Morales & Ribas present a comprehensive analysis of multi-color light and radial velocity curves for this system. The GU Boo light curves presented by López-Morales & Ribas had substantial asymmetries, which were attributed to large spots. In spite of the asymmetry, López-Morales & Ribas derived masses and radii accurate to sime2%. We obtained additional photometry of GU Boo using both a CCD and a single-channel photometer and modeled the light curves with the ELC software to determine if the large spots in the light curves give rise to systematic errors at the few percent level. We also modeled the original light curves from the work of López-Morales & Ribas using models with and without spots. We derived a radius of the primary of 0.6329 ± 0.0026 R sun, 0.6413 ± 0.0049 R sun, and 0.6373 ± 0.0029 R sun from the CCD, photoelectric, and López-Morales & Ribas data, respectively. Each of these measurements agrees with the value reported by López-Morales & Ribas (R 1 = 0.623 ± 0.016 R sun) at the level of ≈2%. In addition, the spread in these values is ≈1%-2% from the mean. For the secondary, we derive radii of 0.6074 ± 0.0035 R sun, 0.5944 ± 0.0069 R sun, and 0.5976 ± 0.0059 R sun from the three respective data sets. The López-Morales & Ribas value is R 2 = 0.620 ± 0.020 R sun, which is ≈2%-3% larger than each of the three values we found. The spread in these values is ≈2% from the mean. The systematic difference between our three determinations of the secondary radius and that of López-Morales & Ribas might be attributed to differences in the modeling process and codes used. Our own fits suggest that, for GU Boo at least, using accurate spot modeling of a single set of multi-color light curves results in radii determinations accurate at the ≈2% level.

THE EFFECT OF STARSPOTS ON ACCURATE RADIUS DETERMINATION OF THE LOW-MASS DOUBLE-LINED ECLIPSING BINARY GU Boo

International Nuclear Information System (INIS)

Windmiller, G.; Orosz, J. A.; Etzel, P. B.

2010-01-01

GU Boo is one of only a relatively small number of well-studied double-lined eclipsing binaries that contain low-mass stars. Lopez-Morales and Ribas present a comprehensive analysis of multi-color light and radial velocity curves for this system. The GU Boo light curves presented by Lopez-Morales and Ribas had substantial asymmetries, which were attributed to large spots. In spite of the asymmetry, Lopez-Morales and Ribas derived masses and radii accurate to ≅2%. We obtained additional photometry of GU Boo using both a CCD and a single-channel photometer and modeled the light curves with the ELC software to determine if the large spots in the light curves give rise to systematic errors at the few percent level. We also modeled the original light curves from the work of Lopez-Morales and Ribas using models with and without spots. We derived a radius of the primary of 0.6329 ± 0.0026 R sun , 0.6413 ± 0.0049 R sun , and 0.6373 ± 0.0029 R sun from the CCD, photoelectric, and Lopez-Morales and Ribas data, respectively. Each of these measurements agrees with the value reported by Lopez-Morales and Ribas (R 1 = 0.623 ± 0.016 R sun ) at the level of ∼2%. In addition, the spread in these values is ∼1%-2% from the mean. For the secondary, we derive radii of 0.6074 ± 0.0035 R sun , 0.5944 ± 0.0069 R sun , and 0.5976 ± 0.0059 R sun from the three respective data sets. The Lopez-Morales and Ribas value is R 2 = 0.620 ± 0.020 R sun , which is ∼2%-3% larger than each of the three values we found. The spread in these values is ∼2% from the mean. The systematic difference between our three determinations of the secondary radius and that of Lopez-Morales and Ribas might be attributed to differences in the modeling process and codes used. Our own fits suggest that, for GU Boo at least, using accurate spot modeling of a single set of multi-color light curves results in radii determinations accurate at the ∼2% level.

Closed Paths of Light Trapped in a Closed Fermat Curve

Science.gov (United States)

Dana-Picard, Thierry; Naiman, Aaron

2002-01-01

Geometric constructions have previously been shown that can be interpreted as rays of light trapped either in polygons or in conics, by successive reflections. The same question, trapping light in closed Fermat curves, is addressed here. Numerical methods are used to study the behaviour of the reflection points of a triangle when the degree of the…

THE PERIOD VARIATION OF AND A SPOT MODEL FOR THE ECLIPSING BINARY AR BOOTIS

International Nuclear Information System (INIS)

Lee, Jae Woo; Youn, Jae-Hyuck; Lee, Chung-Uk; Kim, Seung-Lee; Koch, Robert H.

2009-01-01

New CCD photometric observations of the eclipsing system AR Boo were obtained from 2006 February to 2008 April. The star's photometric properties are derived from detailed studies of the period variability and of all available light curves. We find that over about 56 yr the orbital period of the system has varied due to a combination of an upward parabola and a sinusoid rather than in a monotonic fashion. Mass transfer from the less massive primary to the more massive secondary component is likely responsible for at least a significant part of the secular period change. The cyclical variation with a period of 7.57 yr and a semi-amplitude of 0.0015 d can be produced either by a light-travel-time effect due to an unseen companion with a scaled mass of M 3 sin i 3 = 0.081 M sun or by a magnetic period modulation in the secondary star. Historical light curves of AR Boo, as well as our own, display season-to-season light variability, which are best modeled by including both a cool spot and a hot one on the secondary star. We think that the spots express magnetic dynamo-related activity and offer limited support for preferring the magnetic interpretation of the 7.57 yr cycle over the third-body interpretation. Our solutions confirm that AR Boo belongs to the W-subtype contact binary class, consisting of a hotter, less massive primary star with a spectral type of G9 and a companion of spectral type K1.

THE INFORMATION CONTENT IN ANALYTIC SPOT MODELS OF BROADBAND PRECISION LIGHT CURVES

Energy Technology Data Exchange (ETDEWEB)

Walkowicz, Lucianne M. [Department of Astrophysical Sciences, Princeton University, Peyton Hall, 4 Ivy Lane, Princeton, NJ 08534 (United States); Basri, Gibor [Astronomy Department, University of California at Berkeley, Hearst Field Annex, Berkeley, CA 94720 (United States); Valenti, Jeff A. [Space Telescope Science Institute, 3700 San Martin Dr., Baltimore, MD 21218 (United States)

2013-04-01

We present the results of numerical experiments to assess degeneracies in light curve models of starspots. Using synthetic light curves generated with the Cheetah starspot modeling code, we explore the extent to which photometric light curves constrain spot model parameters, including spot latitudes and stellar inclination. We also investigate the effects of spot parameters and differential rotation on one's ability to correctly recover rotation periods and differential rotation in the Kepler light curves. We confirm that in the absence of additional constraints on the stellar inclination, such as spectroscopic measurements of vsin i or occultations of starspots by planetary transits, the spot latitude and stellar inclination are difficult to determine uniquely from the photometry alone. We find that for models with no differential rotation, spots that appear on opposite hemispheres of the star may cause one to interpret the rotation period to be half of the true period. When differential rotation is included, the changing longitude separation between spots breaks the symmetry of the hemispheres and the correct rotation period is more likely to be found. The dominant period found via periodogram analysis is typically that of the largest spot. Even when multiple spots with periods representative of the star's differential rotation exist, if one spot dominates the light curve the signal of differential rotation may not be detectable from the periodogram alone. Starspot modeling is applicable to stars with a wider range of rotation rates than other surface imaging techniques (such as Doppler imaging), allows subtle signatures of differential rotation to be measured, and may provide valuable information on the distribution of stellar spots. However, given the inherent degeneracies and uncertainty present in starspot models, caution should be exercised in their interpretation.

THE INFORMATION CONTENT IN ANALYTIC SPOT MODELS OF BROADBAND PRECISION LIGHT CURVES

International Nuclear Information System (INIS)

Walkowicz, Lucianne M.; Basri, Gibor; Valenti, Jeff A.

2013-01-01

We present the results of numerical experiments to assess degeneracies in light curve models of starspots. Using synthetic light curves generated with the Cheetah starspot modeling code, we explore the extent to which photometric light curves constrain spot model parameters, including spot latitudes and stellar inclination. We also investigate the effects of spot parameters and differential rotation on one's ability to correctly recover rotation periods and differential rotation in the Kepler light curves. We confirm that in the absence of additional constraints on the stellar inclination, such as spectroscopic measurements of vsin i or occultations of starspots by planetary transits, the spot latitude and stellar inclination are difficult to determine uniquely from the photometry alone. We find that for models with no differential rotation, spots that appear on opposite hemispheres of the star may cause one to interpret the rotation period to be half of the true period. When differential rotation is included, the changing longitude separation between spots breaks the symmetry of the hemispheres and the correct rotation period is more likely to be found. The dominant period found via periodogram analysis is typically that of the largest spot. Even when multiple spots with periods representative of the star's differential rotation exist, if one spot dominates the light curve the signal of differential rotation may not be detectable from the periodogram alone. Starspot modeling is applicable to stars with a wider range of rotation rates than other surface imaging techniques (such as Doppler imaging), allows subtle signatures of differential rotation to be measured, and may provide valuable information on the distribution of stellar spots. However, given the inherent degeneracies and uncertainty present in starspot models, caution should be exercised in their interpretation.

Light and optics principles and practices

CERN Document Server

Al-Azzawi, Abdul

2007-01-01

THE NATURE OF LIGHTIntroductionThe Evolution of Light TheoryMeasurements of the Speed of LightLight SourcesThe Electromagnetic SpectrumTypes of Electromagnetic WavesProperties of LightFurther ReadingLIGHT AND SHADOWSIntroductionShadowsSolar EclipseLunar EclipseApplications of ShadowsExperimental WorkList of ReferencesAppendicesFurther ReadingTHERMAL RADIATIONIntroductionThermal RadiationLight and EnergySolar Radiation EnergyClassification of Solar CollectorsFlat-Plate CollectorsSolar Heating SystemsHot Water and Steam Generation SystemsVapour Absorption Refrigeration/Air Conditioning SystemsPh

EXTRASOLAR STORMS: PRESSURE-DEPENDENT CHANGES IN LIGHT-CURVE PHASE IN BROWN DWARFS FROM SIMULTANEOUS HST AND SPITZER OBSERVATIONS

Energy Technology Data Exchange (ETDEWEB)

Yang, Hao; Apai, Dániel; Karalidi, Theodora [Department of Astronomy, University of Arizona, 933 N. Cherry Ave., Tucson, AZ 85721 (United States); Marley, Mark S. [NASA Ames Research Center, Naval Air Station, Moffett Field, Mountain View, CA 94035 (United States); Flateau, Davin [Department of Planetary Sciences, 1629 E. University Blvd., Tucson, AZ 85721 (United States); Showman, Adam P. [Department of Planetary Sciences, University of Arizona, 1629 University Blvd., Tucson, AZ 85721 (United States); Metchev, Stanimir [The University of Western Ontario, Department of Physics and Astronomy, Centre for Planetary Science and Exploration, 1151 Richmond St., London, ON N6A 3K7 (Canada); Buenzli, Esther [Institute for Astronomy, ETH Zürich Wolfgang-Pauli-Str. 27, 8093 Zürich (Switzerland); Radigan, Jacqueline [Space Telescope Science Institute, 3700 San Martin Dr., Baltimore, MD 21218 (United States); Artigau, Étienne [Département de Physique, Université de Montréal, C.P. 6128 Succ. Centre-ville, Montréal, QC H3C 3J7 (Canada); Lowrance, Patrick J. [Infrared Processing and Analysis Center, MS 100-22, California Institute of Technology, Pasadena, CA 91125 (United States); Burgasser, Adam J., E-mail: haoyang@email.arizona.edu, E-mail: apai@arizona.edu [Center for Astrophysics and Space Science, University of California, San Diego, La Jolla, CA 92093 (United States)

2016-07-20

We present Spitzer /Infrared Array Camera Ch1 and Ch2 monitoring of six brown dwarfs during eight different epochs over the course of 20 months. For four brown dwarfs, we also obtained simulataneous Hubble Space Telescope ( HST )/WFC3 G141 grism spectra during two epochs and derived light curves in five narrowband filters. Probing different pressure levels in the atmospheres, the multiwavelength light curves of our six targets all exhibit variations, and the shape of the light curves evolves over the timescale of a rotation period, ranging from 1.4 to 13 hr. We compare the shapes of the light curves and estimate the phase shifts between the light curves observed at different wavelengths by comparing the phase of the primary Fourier components. We use state-of-the-art atmosphere models to determine the flux contribution of different pressure layers to the observed flux in each filter. We find that the light curves that probe higher pressures are similar and in phase, but are offset and often different from the light curves that probe lower pressures. The phase differences between the two groups of light curves suggest that the modulations seen at lower and higher pressures may be introduced by different cloud layers.

Photometric light curves for seven rapidly-rotating K dwarfs in the Pleiades and Alpha Persei clusters

Science.gov (United States)

Stauffer, John R.; Schild, Rudolph A.; Baliunas, Sallie L.; Africano, John L.

1987-01-01

Light curves and period estimates were obtained for several Pleiades and Alpha Persei cluster K dwarfs which were identified as rapid rotators in earlier spectroscopic studies. A few of the stars have previously-published light curves, making it possible to study the long-term variability of the light-curve shapes. The general cause of the photometric variability observed for these stars is an asymmetric distribution of photospheric inhomogeneities (starspots). The presence of these inhomogeneities combined with the rotation of the star lead to the light curves observed. The photometric periods derived are thus identified with the rotation period of the star, making it possible to estimate equatorial rotational velocities for these K dwarfs. These data are of particular importance because the clusters are sufficiently young that stars of this mass should have just arrived on the main sequence. These data could be used to estimate the temperatures and sizes of the spot groups necessary to produce the observed light curves for these stars.

Analysis of 45-years of Eclipse Timings of the Hyades (K2 V+ DA) Eclipsing Binary V471 Tauri

Science.gov (United States)

Marchioni, Lucas; Guinan, Edward; Engle, Scott

2018-01-01

V471 Tau is an important detached 0.521-day eclipsing binary composed of a K2 V and a hot DA white dwarf star. This system resides in the Hyades star cluster located approximately 153 Ly from us. V471 Tau is considered to be the end-product of common-envelope binary star evolution and is currently a pre-CV system. V471 Tau serves as a valuable astrophysical laboratory for studying stellar evolution, white dwarfs, stellar magnetic dynamos, and possible detection of low mass companions using the Light Travel Time (LTT) Effects. Since its discovery as an eclipsing binary in 1970, photometry has been carried out and many eclipse timings have been determined. We have performed an analysis of the available photometric data available on V471 Tauri. The binary system has been the subject of analyses regarding the orbital period. From this analysis several have postulated the existence of a third body in the form of a brown dwarf that is causing periodic variations in the system’s apparent period. In this study we combine ground based data with photometry secured recently from the Kepler K2 mission. After detrending and phasing the available data, we are able to compare the changing period of the eclipsing binary system against predictions on the existence of this third body. The results of the analysis will be presented. This research is sponsored by grants from NASA and NSF for which we are very grateful.

Orbital Signatures from Observed Light Curves of Blazars

Indian Academy of Sciences (India)

2016-01-27

Jan 27, 2016 ... Variability in active galactic nuclei is observed in UV to X-ray emission based light curves. This could be attributed to orbital signatures of the plasma that constitutes the accretion flow on the putative disk or in the developing jet close to the inner region of the central black hole. We discuss some theoretical ...

Eclipse studies of the dwarf nova Oy Carinae in quiescence

International Nuclear Information System (INIS)

Wood, J.H.; Horne, K.; Berriman, G.; Wade, R.A.

1989-01-01

High-speed photometry of OY Car have been obtained which cover 20 eclipses in white light and seven eclipses in UBR. The results show the red dwarf to have a mass of 0.070 + or - 0.002 solar masses and a radius of 0.127 + or - 0.002 solar radii, and the white dwarf to have a temperature of several thousand degrees below 15,000 K. The bright spot is found to have a compact 15,000-K core and a tail that extends along the rim but does not penetrate far into the disk. 31 refs

A Comprehensive Catalog of Galactic Eclipsing Binary Stars with Eccentric Orbits Based on Eclipse Timing Diagrams

Science.gov (United States)

Kim, C.-H.; Kreiner, J. M.; Zakrzewski, B.; Ogłoza, W.; Kim, H.-W.; Jeong, M.-J.

2018-04-01

A comprehensive catalog of 623 galactic eclipsing binary (EB) systems with eccentric orbits is presented with more than 2830 times of minima determined from the archived photometric data by various sky-survey projects and new photometric measurements. The systems are divided into two groups according to whether the individual system has a GCVS name or not. All the systems in both groups are further classified into three categories (D, A, and A+III) on the basis of their eclipse timing diagrams: 453 D systems showing just constantly displaced secondary minima, 139 A systems displaying only apsidal motion (AM), and 31 A+III systems exhibiting both AM and light-time effects. AM parameters for 170 systems (A and A+III systems) are consistently calculated and cataloged with basic information for all systems. Some important statistics for the AM parameters are discussed and compared with those derived for the eccentric EB systems in the Large and Small Magellanic Clouds.

Infrared rotational light curves on Jupiter induced by wave activities and cloud patterns andimplications on brown dwarfs

Science.gov (United States)

Ge, Huazhi; Zhang, Xi; Fletcher, Leigh; Orton, Glenn S.; Sinclair, James Andrew; Fernandes,, Joshua; Momary, Thomas W.; Warren, Ari; Kasaba, Yasumasa; Sato, Takao M.; Fujiyoshi, Takuya

2017-10-01

Many brown dwarfs exhibit infrared rotational light curves with amplitude varying from a fewpercent to twenty percent (Artigau et al. 2009, ApJ, 701, 1534; Radigan et al. 2012, ApJ, 750,105). Recently, it was claimed that weather patterns, especially planetary-scale waves in thebelts and cloud spots, are responsible for the light curves and their evolutions on brown dwarfs(Apai et al. 2017, Science, 357, 683). Here we present a clear relationship between the direct IRemission maps and light curves of Jupiter at multiple wavelengths, which might be similar withthat on cold brown dwarfs. Based on infrared disk maps from Subaru/COMICS and VLT/VISIR,we constructed full maps of Jupiter and rotational light curves at different wavelengths in thethermal infrared. We discovered a strong relationship between the light curves and weatherpatterns on Jupiter. The light curves also exhibit strong multi-bands phase shifts and temporalvariations, similar to that detected on brown dwarfs. Together with the spectra fromTEXES/IRTF, our observations further provide detailed information of the spatial variations oftemperature, ammonia clouds and aerosols in the troposphere of Jupiter (Fletcher et al. 2016,Icarus, 2016 128) and their influences on the shapes of the light curves. We conclude that waveactivities in Jupiter’s belts (Fletcher et al. 2017, GRL, 44, 7140), cloud holes, and long-livedvortices such as the Great Red Spot and ovals control the shapes of IR light curves and multi-wavelength phase shifts on Jupiter. Our finding supports the hypothesis that observed lightcurves on brown dwarfs are induced by planetary-scale waves and cloud spots.

KIC 6048106: an Algol-type eclipsing system with long-term magnetic activity and hybrid pulsations - I. Binary modelling

Science.gov (United States)

Samadi Ghadim, A.; Lampens, P.; Jassur, M.

2018-03-01

The A-F-type stars and pulsators (δ Scuti-γ Dor) are in a critical regime where they experience a transition from radiative to convective transport of energy in their envelopes. Such stars can pulsate in both gravity and acoustic modes. Hence, the knowledge of their fundamental parameters along with their observed pulsation characteristics can help in improving the stellar models. When residing in a binary system, these pulsators provide more accurate and less model-dependent stellar parameters than in the case of their single counterparts. We present a light-curve model for the eclipsing system KIC 6048106 based on the Kepler photometry and the code PHOEBE. We aim to obtain accurate physical parameters and tough constraints for the stellar modelling of this intermediate-mass hybrid pulsator. We performed a separate modelling of three light-curve segments which show a distinct behaviour due to a difference in activity. We also analysed the Kepler Eclipse Time Variations (ETVs). KIC 6048106 is an Algol-type binary with F5-K5 components, a near-circular orbit and a 1.56-d period undergoing variations of the order of Δ P/P˜eq 3.60× 10^{-7} in 287 ± 7 d. The primary component is a main-sequence star with M1 = 1.55 ± 0.11 M⊙, R1 = 1.57 ± 0.12 R⊙. The secondary is a much cooler subgiant with M2 = 0.33 ± 0.07 M⊙, R2 = 1.77 ± 0.16 R⊙. Many small near-polar spots are active on its surface. The second quadrature phase shows a brightness modulation on a time-scale 290 ± 7 d, in good agreement with the ETV modulation. This study reveals a stable binary configuration along with clear evidence of a long-term activity of the secondary star.

David Levy's Guide to Eclipses, Transits, and Occultations

Science.gov (United States)

Levy, David H.

2010-08-01

Introduction; Part I. The Magic and History of Eclipses: 1. Shakespeare, King Lear, and the Great Eclipse of 1605; 2. Three centuries later: Einstein, relativity, and the solar eclipse of 1919; 3. What causes solar and lunar eclipses; Part II. Observing Solar Eclipses: 4. Safety considerations; 5. What to expect during a partial eclipse; 6. Annular eclipses and what to see in them; 7. Total eclipse of the Sun: introduction to the magic; 8. The onset: temperature drop, Baily's Beads, Diamond Ring; 9. Totality: Corona, Prominences, Chromosphere, and surrounding area; 10. Photographing and imaging a solar eclipse; Part III. Observing Lunar Eclipses: 11. Don't forget the penumbral eclipses!; 12. Partial lunar eclipses; 13. Total lunar eclipses; 14. Photographing and imaging lunar eclipses; Part IV. Occultations: 15. When the Moon occults a star; Part V. Transits: 16. When planets cross the Sun; Part VI. My Favorite Eclipses: 17. A personal canon of eclipses, occultations, and transits I have seen; Appendices; Index.

Absolute parameters of southern detached eclipsing binary: HD 53570

Science.gov (United States)

Sürgit, D.

2018-05-01

In this study, we conducted the first analysis of spectroscopic and photometric observations of the eclipsing binary star HD 53570. Spectroscopic observations of HD 53570 were made at the Sutherland Station of the South African Astronomical Observatory in 2013 and 2014. The radial velocities of the components were determined using the cross-correlation technique. The spectroscopic mass ratio obtained for the system was 1.13 ( ± 0.07). The All Sky Automated Survey V light curve of HD 53570 was analyzed using the Wilson-Devinney code combined with the Monte Carlo search method. The final model showed that HD 53570 has a detached configuration. The mass and radii of the primary and secondary components of HD 53570 were derived as 1.06 ( ± 0.07) M⊙, 1.20 ( ± 0.16) M⊙, and 1.42 ( ± 0.14) R⊙, 2.07 ( ± 0.16) R⊙, respectively. The distance of HD 53570 was computed as 248 ( ± 38) pc considering interstellar extinction. The evolutionary status of the component stars was also investigated using Geneva evolutionary models.

Type IIP supernova light curves affected by the acceleration of red supergiant winds

Science.gov (United States)

Moriya, Takashi J.; Förster, Francisco; Yoon, Sung-Chul; Gräfener, Götz; Blinnikov, Sergei I.

2018-05-01

We introduce the first synthetic light-curve model set of Type IIP supernovae exploded within circumstellar media in which the acceleration of the red supergiant winds is taken into account. Because wind acceleration makes the wind velocities near the progenitors low, the density of the immediate vicinity of the red supergiant supernova progenitors can be higher than that extrapolated by using a constant terminal wind velocity. Therefore, even if the mass-loss rate of the progenitor is relatively low, it can have a dense circumstellar medium at the immediate stellar vicinity and the early light curves of Type IIP supernovae are significantly affected by it. We adopt a simple β velocity law to formulate the wind acceleration. We provide bolometric and multicolour light curves of Type IIP supernovae exploding within such accelerated winds from the combinations of three progenitors, 12-16 M⊙; five β, 1-5; seven mass-loss rates, 10-5-10-2 M⊙ yr-1; and four explosion energies, (0.5-2) × 1051 erg. All the light-curve models are available at https://goo.gl/o5phYb. When the circumstellar density is sufficiently high, our models do not show a classical shock breakout as a consequence of the interaction with the dense and optically thick circumstellar media. Instead, they show a delayed `wind breakout', substantially affecting early light curves of Type IIP supernovae. We find that the mass-loss rates of the progenitors need to be 10-3-10-2 M⊙ yr-1 to explain typical rise times of 5-10 d in Type IIP supernovae assuming a dense circumstellar radius of 1015 cm.

SIMULATED PERFORMANCE OF TIMESCALE METRICS FOR APERIODIC LIGHT CURVES

Energy Technology Data Exchange (ETDEWEB)

Findeisen, Krzysztof; Hillenbrand, Lynne [Cahill Center for Astronomy and Astrophysics, California Institute of Technology, MC 249-17, Pasadena, CA 91125 (United States); Cody, Ann Marie, E-mail: krzys@astro.caltech.edu [Spitzer Science Center, California Institute of Technology, MC 314-6, Pasadena, CA 91125 (United States)

2015-01-10

Aperiodic variability is a characteristic feature of young stars, massive stars, and active galactic nuclei. With the recent proliferation of time-domain surveys, it is increasingly essential to develop methods to quantify and analyze aperiodic variability. We develop three timescale metrics that have been little used in astronomy—Δm-Δt plots, peak-finding, and Gaussian process regression—and present simulations comparing their effectiveness across a range of aperiodic light curve shapes, characteristic timescales, observing cadences, and signal to noise ratios. We find that Gaussian process regression is easily confused by noise and by irregular sampling, even when the model being fit reflects the process underlying the light curve, but that Δm-Δt plots and peak-finding can coarsely characterize timescales across a broad region of parameter space. We make public the software we used for our simulations, both in the spirit of open research and to allow others to carry out analogous simulations for their own observing programs.

SIMULATED PERFORMANCE OF TIMESCALE METRICS FOR APERIODIC LIGHT CURVES

International Nuclear Information System (INIS)

Findeisen, Krzysztof; Hillenbrand, Lynne; Cody, Ann Marie

2015-01-01

Aperiodic variability is a characteristic feature of young stars, massive stars, and active galactic nuclei. With the recent proliferation of time-domain surveys, it is increasingly essential to develop methods to quantify and analyze aperiodic variability. We develop three timescale metrics that have been little used in astronomy—Δm-Δt plots, peak-finding, and Gaussian process regression—and present simulations comparing their effectiveness across a range of aperiodic light curve shapes, characteristic timescales, observing cadences, and signal to noise ratios. We find that Gaussian process regression is easily confused by noise and by irregular sampling, even when the model being fit reflects the process underlying the light curve, but that Δm-Δt plots and peak-finding can coarsely characterize timescales across a broad region of parameter space. We make public the software we used for our simulations, both in the spirit of open research and to allow others to carry out analogous simulations for their own observing programs

Flare Characteristics from X-ray Light Curves

Science.gov (United States)

Gryciuk, M.; Siarkowski, M.; Sylwester, J.; Gburek, S.; Podgorski, P.; Kepa, A.; Sylwester, B.; Mrozek, T.

2017-06-01

A new methodology is given to determine basic parameters of flares from their X-ray light curves. Algorithms are developed from the analysis of small X-ray flares occurring during the deep solar minimum of 2009, between Solar Cycles 23 and 24, observed by the Polish Solar Photometer in X-rays (SphinX) on the Complex Orbital Observations Near-Earth of Activity of the Sun-Photon (CORONAS- Photon) spacecraft. One is a semi-automatic flare detection procedure that gives start, peak, and end times for single ("elementary") flare events under the assumption that the light curve is a simple convolution of a Gaussian and exponential decay functions. More complex flares with multiple peaks can generally be described by a sum of such elementary flares. Flare time profiles in the two energy ranges of SphinX (1.16 - 1.51 keV, 1.51 - 15 keV) are used to derive temperature and emission measure as a function of time during each flare. The result is a comprehensive catalogue - the SphinX Flare Catalogue - which contains 1600 flares or flare-like events and is made available for general use. The methods described here can be applied to observations made by Geosynchronous Operational Environmental Satellites (GOES), the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) and other broad-band spectrometers.

REVISITING EVIDENCE OF CHAOS IN X-RAY LIGHT CURVES: THE CASE OF GRS 1915+105

Energy Technology Data Exchange (ETDEWEB)

Mannattil, Manu; Gupta, Himanshu; Chakraborty, Sagar, E-mail: mmanu@iitk.ac.in, E-mail: hiugupta@iitk.ac.in, E-mail: sagarc@iitk.ac.in [Department of Physics, Indian Institute of Technology Kanpur, Uttar Pradesh 208016 (India)

2016-12-20

Nonlinear time series analysis has been widely used to search for signatures of low-dimensional chaos in light curves emanating from astrophysical bodies. A particularly popular example is the microquasar GRS 1915+105, whose irregular but systematic X-ray variability has been well studied using data acquired by the Rossi X-ray Timing Explorer . With a view to building simpler models of X-ray variability, attempts have been made to classify the light curves of GRS 1915+105 as chaotic or stochastic. Contrary to some of the earlier suggestions, after careful analysis, we find no evidence for chaos or determinism in any of the GRS 1915+105 classes. The dearth of long and stationary data sets representing all the different variability classes of GRS 1915+105 makes it a poor candidate for analysis using nonlinear time series techniques. We conclude that either very exhaustive data analysis with sufficiently long and stationary light curves should be performed, keeping all the pitfalls of nonlinear time series analysis in mind, or alternative schemes of classifying the light curves should be adopted. The generic limitations of the techniques that we point out in the context of GRS 1915+105 affect all similar investigations of light curves from other astrophysical sources.

THE PALOMAR TRANSIENT FACTORY ORION PROJECT: ECLIPSING BINARIES AND YOUNG STELLAR OBJECTS

International Nuclear Information System (INIS)

Van Eyken, Julian C.; Ciardi, David R.; Akeson, Rachel L.; Beichman, Charles A.; Von Braun, Kaspar; Gelino, Dawn M.; Kane, Stephen R.; Plavchan, Peter; RamIrez, Solange V.; Rebull, Luisa M.; Stauffer, John R.; Hoard, D. W.; Boden, Andrew F.; Howell, Steve B.; Bloom, Joshua S.; Cenko, S. Bradley; Kasliwal, Mansi M.; Kulkarni, Shrinivas R.; Law, Nicholas M.; Nugent, Peter E.

2011-01-01

The Palomar Transient Factory (PTF) Orion project is one of the experiments within the broader PTF survey, a systematic automated exploration of the sky for optical transients. Taking advantage of the wide (3. 0 5 x 2. 0 3) field of view available using the PTF camera installed at the Palomar 48 inch telescope, 40 nights were dedicated in 2009 December to 2010 January to perform continuous high-cadence differential photometry on a single field containing the young (7-10 Myr) 25 Ori association. Little is known empirically about the formation of planets at these young ages, and the primary motivation for the project is to search for planets around young stars in this region. The unique data set also provides for much ancillary science. In this first paper, we describe the survey and the data reduction pipeline, and present some initial results from an inspection of the most clearly varying stars relating to two of the ancillary science objectives: detection of eclipsing binaries and young stellar objects. We find 82 new eclipsing binary systems, 9 of which are good candidate 25 Ori or Orion OB1a association members. Of these, two are potential young W UMa type systems. We report on the possible low-mass (M-dwarf primary) eclipsing systems in the sample, which include six of the candidate young systems. Forty-five of the binary systems are close (mainly contact) systems, and one of these shows an orbital period among the shortest known for W UMa binaries, at 0.2156509 ± 0.0000071 days, with flat-bottomed primary eclipses, and a derived distance that appears consistent with membership in the general Orion association. One of the candidate young systems presents an unusual light curve, perhaps representing a semi-detached binary system with an inflated low-mass primary or a star with a warped disk, and may represent an additional young Orion member. Finally, we identify 14 probable new classical T-Tauri stars in our data, along with one previously known (CVSO 35) and

A Semiautomatic Pipeline for Be Star Light Curves

Science.gov (United States)

Rímulo, L. R.; Carciofi, A. C.; Rivinius, T.; Okazaki, A.

2016-11-01

Observational and theoretical studies from the last decade have shown that the Viscous Decretion Disk (VDD) scenario, in which turbulent viscosity is the physical mechanism responsible for the transport of material and angular momentum ejected from the star to the outer regions of the disk, is the only viable model for explaining the circumstellar disks of Be stars. In the α-disk approach applied to the VDD, the dimensionless parameter α is a measure of the turbulent viscosity. Recently, combining the time-dependent evolution of a VDD α-disk with non-LTE radiative transfer calculations, the first measurement of the α parameter was made, for the disk dissipation of the Be star ω CMa. It was found that α≍ 1 for that Be disk. The main motivation of this present work is the statistical determination of the α parameter. For this purpose, we present a pipeline that will allow the semiautomatic determination of the α parameter of several dozens of light curves of Be stars available from photometric surveys, In this contribution, we describe the pipeline, outlining the main staps required for the semiautomatic analysis of light curves

A method for the rapid generation of nonsequential light-response curves of chlorophyll fluorescence.

Science.gov (United States)

Serôdio, João; Ezequiel, João; Frommlet, Jörg; Laviale, Martin; Lavaud, Johann

2013-11-01

Light-response curves (LCs) of chlorophyll fluorescence are widely used in plant physiology. Most commonly, LCs are generated sequentially, exposing the same sample to a sequence of distinct actinic light intensities. These measurements are not independent, as the response to each new light level is affected by the light exposure history experienced during previous steps of the LC, an issue particularly relevant in the case of the popular rapid light curves. In this work, we demonstrate the proof of concept of a new method for the rapid generation of LCs from nonsequential, temporally independent fluorescence measurements. The method is based on the combined use of sample illumination with digitally controlled, spatially separated beams of actinic light and a fluorescence imaging system. It allows the generation of a whole LC, including a large number of actinic light steps and adequate replication, within the time required for a single measurement (and therefore named "single-pulse light curve"). This method is illustrated for the generation of LCs of photosystem II quantum yield, relative electron transport rate, and nonphotochemical quenching on intact plant leaves exhibiting distinct light responses. This approach makes it also possible to easily characterize the integrated dynamic light response of a sample by combining the measurement of LCs (actinic light intensity is varied while measuring time is fixed) with induction/relaxation kinetics (actinic light intensity is fixed and the response is followed over time), describing both how the response to light varies with time and how the response kinetics varies with light intensity.

Photometric Observation and Light Curve Analysis of Binary System ...

Indian Academy of Sciences (India)

2016-01-27

Jan 27, 2016 ... Photometric Observation and Light Curve Analysis of Binary System ER-Orionis ... February to April 2008 with the 51 cm telescope of Biruni Observatory of Shiraz University in U, B and V filters (Johnson system) and an RCA 4509 photomultiplier. ... Articles are also visible in Web of Science immediately.

Candidate Binary Trojan and Hilda Asteroids from Rotational Light Curves

Science.gov (United States)

Sonnett, Sarah M.; Mainzer, Amy K.; Grav, Tommy; Masiero, Joseph R.; Bauer, James M.; Kramer, Emily A.

2017-10-01

Jovian Trojans (hereafter, Trojans) are asteroids in stable orbits at Jupiter's L4 and L5 Lagrange points, and Hilda asteroids are inwards of the Trojans in 3:2 mean-motion resonance with Jupiter. Due to their special dynamical properties, observationally constraining the formation location and dynamical histories of Trojans and HIldas offers key input for giant planet migration models. A fundamental parameter in assessing formation location is the bulk density - with low-density objects associated with an ice-rich formation environment in the outer solar system and high-density objects typically linked to the warmer inner solar system. Bulk density can only be directly measured during a close fly-by or by determining the mutual orbits of binary asteroid systems. With the aim of determining densities for a statistically significant sample of Trojans and Hildas, we are undertaking an observational campaign to confirm and characterize candidate binary asteroids published in Sonnett et al. (2015). These objects were flagged as binary candidates because their large NEOWISE brightness variations imply shapes so elongated that they are not likely explained by a singular equilibrium rubble pile and instead may be two elongated, gravitationally bound asteroids. We are obtaining densely sampled rotational light curves of these possible binaries to search for light curve features diagnostic of binarity and to determine the orbital properties of any confirmed binary systems by modeling the light curve. We compare the We present an update on this follow-up campaign and comment on future steps.

Physical Properties of the LMC Eclipsing Binary Stars

Science.gov (United States)

Prsa, Andrej; Devinney, E. J.; Guinan, E. F.; Engle, S. G.; DeGeorge, M.

2009-01-01

To date, three independent studies have devised an automatic procedure to analyse and extract the principal parameters of 2581 detached eclipsing binary stars from the OGLE photometric survey of the Large Magellanic Cloud (LMC): Devor (2005), Tamuz et al. (2006), and Prsa et al. (2008). For time efficiency, Devor used a simple model of two spherical, limb-darkened stars without tidal or reflection physics. Tamuz et al.'s approach employs a more realistic EBOP model, which is still limited in handling proximity physics. Our study used a back-propagating neural network that was trained on the light curves computed by a modern Wilson-Devinney code. The three approaches are confronted and correlations in the results are sought that indicate the degree of reliability of the obtained results. A database of solutions consistent across all three studies is presented. We assess the suitability of each method for other morphology types (i.e. semi-detached and overcontact binaries) and we overview the practical limitations of these methods for the upcoming survey data. This research is supported by NFS/RUI Grant No. AST-05-07542, which we gratefully acknowledge.

Limb darkening laws for two exoplanet host stars derived from 3D stellar model atmospheres. Comparison with 1D models and HST light curve observations

Science.gov (United States)

Hayek, W.; Sing, D.; Pont, F.; Asplund, M.

2012-03-01

We compare limb darkening laws derived from 3D hydrodynamical model atmospheres and 1D hydrostatic MARCS models for the host stars of two well-studied transiting exoplanet systems, the late-type dwarfs HD 209458 and HD 189733. The surface brightness distribution of the stellar disks is calculated for a wide spectral range using 3D LTE spectrum formation and opacity sampling⋆. We test our theoretical predictions using least-squares fits of model light curves to wavelength-integrated primary eclipses that were observed with the Hubble Space Telescope (HST). The limb darkening law derived from the 3D model of HD 209458 in the spectral region between 2900 Å and 5700 Å produces significantly better fits to the HST data, removing systematic residuals that were previously observed for model light curves based on 1D limb darkening predictions. This difference arises mainly from the shallower mean temperature structure of the 3D model, which is a consequence of the explicit simulation of stellar surface granulation where 1D models need to rely on simplified recipes. In the case of HD 189733, the model atmospheres produce practically equivalent limb darkening curves between 2900 Å and 5700 Å, partly due to obstruction by spectral lines, and the data are not sufficient to distinguish between the light curves. We also analyze HST observations between 5350 Å and 10 500 Å for this star; the 3D model leads to a better fit compared to 1D limb darkening predictions. The significant improvement of fit quality for the HD 209458 system demonstrates the higher degree of realism of 3D hydrodynamical models and the importance of surface granulation for the formation of the atmospheric radiation field of late-type stars. This result agrees well with recent investigations of limb darkening in the solar continuum and other observational tests of the 3D models. The case of HD 189733 is no contradiction as the model light curves are less sensitive to the temperature stratification of

Eclipse Megamovie: Solar Discoveries, Education, and Outreach through Crowdsourcing 2017 Eclipse Images

Science.gov (United States)

Peticolas, L. M.; Hudson, H. S.; Martinez Oliveros, J. C.; Johnson, C.; Zevin, D.; Krista, L. D.; Bender, M.; Mcintosh, S. W.; Konerding, D.; Koh, J.; Pasachoff, J.; Lorimore, B.; Jiang, G.; Storksdieck, M.; Yan, D.; Shore, L.; Fraknoi, A.; Filippenko, A.

2016-12-01

Since 2011, a team of solar scientists, eclipse chasers, education and outreach professionals, and film makers have been working to explore the possibility of gathering images from the public during the 2017 eclipse across the United States, to be used for scientific research, education, and enhancing the public's experience of the eclipse. After years of testing the initial ideas, engaging new organizations, and exploring new technologies, our team has developed a blueprint for this project. There are three main goals for this effort: 1. to learn more about the dynamic non-equilibrium processes in the corona and lower atmosphere of the Sun, 2. to educate the public about space physics, 3. provide different levels of engagement opportunities for an interested public, and 4. to understand how these various levels of engagement with a major scientific phenomena allow people to develop deeper personal connections to Science, Technology, Engineering, and Mathematics (STEM). We will meet these goals by training 1000 volunteers to take scientifically valid images and donate the images to this project, while also allowing the general public to share their images as well. During the Aug 21, 2017 eclipse, we will analyze these images in real-time to produce public-generated movies showing the corona of the Sun during totality from thousands of people. These movies will be disseminated in near real-time (on the order of 10s of minutes) to other eclipse programs, news organizations, and to the general public. Meanwhile, images collected during and after the eclipse will be available to scientists and the public for research purposes. To further engage the public, video clips, film, and a documentary will be produced prior and after the event. A science education research team will work alongside the team to understand how the project supports deeper connections to the eclipse experience.

Total eclipses of the sun

CERN Document Server

Zirker, Jack B

2014-01-01

Eclipses have captured attention and sparked curiosity about the cosmos since the first appearance of humankind. Having been blamed for everything from natural disasters to the fall of kings, they are now invaluable tools for understanding many celestial as well as terrestrial phenomena. This clear, easy-to-understand guide explains what causes total eclipses and how they can be used in experiments to examine everything from the dust between the planets to general relativity. A new chapter has been added on the eclipse of July 11, 1991 (the great Hawaiian eclipse). Originally published in 19

SHOCK BREAKOUT AND EARLY LIGHT CURVES OF TYPE II-P SUPERNOVAE OBSERVED WITH KEPLER

International Nuclear Information System (INIS)

Garnavich, P. M.; Tucker, B. E.; Rest, A.; Shaya, E. J.; Olling, R. P.; Kasen, D; Villar, A.

2016-01-01

We discovered two transient events in the Kepler field with light curves that strongly suggest they are type II-P supernovae (SNe II-P). Using the fast cadence of the Kepler observations we precisely estimate the rise time to maximum for KSN2011a and KSN2011d as 10.5 ± 0.4 and 13.3 ± 0.4 rest-frame days, respectively. Based on fits to idealized analytic models, we find the progenitor radius of KSN2011a (280 ± 20 R ⊙ ) to be significantly smaller than that for KSN2011d (490 ± 20 R ⊙ ), but both have similar explosion energies of 2.0 ± 0.3 × 10 51 erg. The rising light curve of KSN2011d is an excellent match to that predicted by simple models of exploding red supergiants (RSG). However, the early rise of KSN2011a is faster than the models predict, possibly due to the supernova shock wave moving into pre-existing wind or mass-loss from the RSG. A mass-loss rate of 10 −4 M ⊙ yr −1 from the RSG can explain the fast rise without impacting the optical flux at maximum light or the shape of the post-maximum light curve. No shock breakout emission is seen in KSN2011a, but this is likely due to the circumstellar interaction suspected in the fast rising light curve. The early light curve of KSN2011d does show excess emission consistent with model predictions of a shock breakout. This is the first optical detection of a shock breakout from a SNe II-P

Photometric Observation and Light Curve Analysis of Binary System ...

Indian Academy of Sciences (India)

Abstract. Photometric observations of the over-contact binary ER ORI were performed during November 2007 and February to April 2008 with the 51cm telescope of Biruni Observatory of Shiraz University in U, B and V filters (Johnson system) and an RCA 4509 photomultiplier. We used these data to obtain the light curves ...

A CHANDRA OBSERVATION OF THE ECLIPSING WOLF-RAYET BINARY CQ Cep

Energy Technology Data Exchange (ETDEWEB)

Skinner, Stephen L. [CASA, Univ. of Colorado, Boulder, CO 80309-0389 (United States); Zhekov, Svetozar A. [Space Research and Technology Institute, Akad. G. Bonchev Str., Sofia, 1113 (Bulgaria); Güdel, Manuel [Dept. of Astrophysics, Univ. of Vienna, Türkenschanzstr. 17, A-1180 Vienna (Austria); Schmutz, Werner, E-mail: stephen.skinner@colorado.edu, E-mail: szhekov@space.bas.bg, E-mail: manuel.guedel@univie.ac.at, E-mail: werner.schmutz@pmodwrc.ch [Physikalisch-Meteorologisches Observatorium Davos and World Radiation Center (PMOD/WRC), Dorfstrasse 33, CH-7260 Davos Dorf (Switzerland)

2015-02-01

The short-period (1.64 d) near-contact eclipsing WN6+O9 binary system CQ Cep provides an ideal laboratory for testing the predictions of X-ray colliding wind shock theory at close separation where the winds may not have reached terminal speeds before colliding. We present results of a Chandra X-ray observation of CQ Cep spanning ∼1 day during which a simultaneous Chandra optical light curve was acquired. Our primary objective was to compare the observed X-ray properties with colliding wind shock theory, which predicts that the hottest shock plasma (T ≳ 20 MK) will form on or near the line-of-centers between the stars. The X-ray spectrum is strikingly similar to apparently single WN6 stars such as WR 134 and spectral lines reveal plasma over a broad range of temperatures T ∼ 4-40 MK. A deep optical eclipse was seen as the O star passed in front of the Wolf-Rayet star and we determine an orbital period P {sub orb} = 1.6412400 d. Somewhat surprisingly, no significant X-ray variability was detected. This implies that the hottest X-ray plasma is not confined to the region between the stars, at odds with the colliding wind picture and suggesting that other X-ray production mechanisms may be at work. Hydrodynamic simulations that account for such effects as radiative cooling and orbital motion will be needed to determine if the new Chandra results can be reconciled with the colliding wind picture.

VizieR Online Data Catalog: Praesepe members light curves (Kovacs+, 2014)

Science.gov (United States)

Kovacs, G.; Hartman, J. D.; Bakos, G. A.; Quinn, S. N.; Penev, K.; Latham, D. W.; Bhatti, W.; Csubry, Z.; de Val-Borro, M.

2014-07-01

Light curves used in the time series analysis of Praesepe are presented. There are 381 light curves on instrumental Sloan r' magnitude scale with the zero points determined by the 2MASS magnitudes according to Eq. (1) of the paper. We present two types of magnitudes: a) external parameter decorrelated (EPD) and b), the ones obtained after the application of a trend filtering algorithm (TFA) on the EPD time series. These two methods are briefly described in the paper and in detail in the references therein. Here we just note that both methods are intended to filter out systematics due to environmental effects (instrumental, weather, etc.). For TFA filtering we used 600 templates and did not apply signal reconstruction. (5 data files).

A unique UV flare in the optical light curve of the quasar J004457.9+412344

Directory of Open Access Journals (Sweden)

Hatzidimitriou D.

2012-12-01

Full Text Available We found that the nova candidate J004457.9+412344 is a radio-quiet quasar at z ∼ 2. Its optical long-term light curve, covering more than half a century, shows quasar typical flux variations superimposed by a spectacular single flare lasting more than one year (observer frame. We could not find comparable light curves among the several thousand catalogued radio-quiet quasars in the stripe 82 of the Sloan Digital Sky Survey. The decreasing part of the flare light curve roughly follows a power law t−5/3. The quasar spectrum, the total energy of the flare, and the decline of the light curve are consistent with the tidal disruption of a ∼10 Mʘ giant star by a supermassive black hole of a few 108 Mʘ. We argue that the alternative explanation by gravitational microlensing is less likely, though it cannot be definitely excluded.

Mapping the 2017 Eclipse: Education, Navigation, Inspiration

Science.gov (United States)

Zeiler, M.

2015-12-01

Eclipse maps are a unique vessel of knowledge. At a glance, they communicate the essential knowledge of where and when to successfully view a total eclipse of the sun. An eclipse map also provides detailed knowledge of eclipse circumstances superimposed on the highway system for optimal navigation, especially in the event that weather forces relocation. Eclipse maps are also a vital planning tool for solar physicists and astrophotographers capturing high-resolution imagery of the solar corona. Michael Zeiler will speak to the role of eclipse maps in educating the American public and inspiring people to make the effort to reach the path of totality for the sight of a lifetime. Michael will review the role of eclipse maps in astronomical research and discuss a project under development, the 2017 Eclipse Atlas for smartphones, tablets, and desktop computers.

Machine Learning Techniques for Stellar Light Curve Classification

Science.gov (United States)

Hinners, Trisha A.; Tat, Kevin; Thorp, Rachel

2018-07-01

We apply machine learning techniques in an attempt to predict and classify stellar properties from noisy and sparse time-series data. We preprocessed over 94 GB of Kepler light curves from the Mikulski Archive for Space Telescopes (MAST) to classify according to 10 distinct physical properties using both representation learning and feature engineering approaches. Studies using machine learning in the field have been primarily done on simulated data, making our study one of the first to use real light-curve data for machine learning approaches. We tuned our data using previous work with simulated data as a template and achieved mixed results between the two approaches. Representation learning using a long short-term memory recurrent neural network produced no successful predictions, but our work with feature engineering was successful for both classification and regression. In particular, we were able to achieve values for stellar density, stellar radius, and effective temperature with low error (∼2%–4%) and good accuracy (∼75%) for classifying the number of transits for a given star. The results show promise for improvement for both approaches upon using larger data sets with a larger minority class. This work has the potential to provide a foundation for future tools and techniques to aid in the analysis of astrophysical data.

Maven for Eclipse

CERN Document Server

Shah, Sanjay

2014-01-01

If you want to learn about Maven and use it from within Eclipse to develop Java projects, this is the book for you. Prior experience in developing Java projects and using the Eclipse IDE is presumed. Whether you are a beginner or an experienced developer, this book will get you up and running quickly, with a hands-on approach.

Red light-induced shift of the fluence-response curve for first positive curvature of maize [Zea mays] coleoptiles

International Nuclear Information System (INIS)

Hofmann, E.; Schäfer, E.

1987-01-01

The fluence-response curve for first positive phototropic curvture of dark-grown maize coleoptiles is shifted to ten-fold higher fluences if the coieoptiles are irradiated with red light 2 h prior to the phototropic induction with blue light. Fluence-response curves for this red-induced shift were obtained with unilateral red irradiations 2 h prior to inductive blue pulses of different fluences. They differ significantly depending on whether the red light was given from the same side as or the opposite side to the respective inductive blue pulse, thus demonstrating that the red light effect is a local response of the coleoptile. The fluence-response curves for an inductive blue pulse in the ascending part were compared with those for an inductive blue pulse in the descending part of the fluence-response curve for blue light induced phototropism. They are quite different in threshold of red light sensitivity and shape for irradiations from both the same and the opposite sides. This offers evidence for the hypothesis that at least two different photosystems are involved in phototropism, and that they are modulated differently by a red light preirradiation. All these fluence-response curves indicate that it is possible to increase the response in the coleoptile, if the red light preirradiation is given opposite to the inductive blue pulse. This is supported by blue light fluence-response curves obtained after a weak unilateral red preirradiation. (author)

Hierarchical Models for Type Ia Supernova Light Curves in the Optical and Near Infrared

Science.gov (United States)

Mandel, Kaisey; Narayan, G.; Kirshner, R. P.

2011-01-01

I have constructed a comprehensive statistical model for Type Ia supernova optical and near infrared light curves. Since the near infrared light curves are excellent standard candles and are less sensitive to dust extinction and reddening, the combination of near infrared and optical data better constrains the host galaxy extinction and improves the precision of distance predictions to SN Ia. A hierarchical probabilistic model coherently accounts for multiple random and uncertain effects, including photometric error, intrinsic supernova light curve variations and correlations across phase and wavelength, dust extinction and reddening, peculiar velocity dispersion and distances. An improved BayeSN MCMC code is implemented for computing probabilistic inferences for individual supernovae and the SN Ia and host galaxy dust populations. I use this hierarchical model to analyze nearby Type Ia supernovae with optical and near infared data from the PAIRITEL, CfA3, and CSP samples and the literature. Using cross-validation to test the robustness of the model predictions, I find that the rms Hubble diagram scatter of predicted distance moduli is 0.11 mag for SN with optical and near infrared data versus 0.15 mag for SN with only optical data. Accounting for the dispersion expected from random peculiar velocities, the rms intrinsic prediction error is 0.08-0.10 mag for SN with both optical and near infrared light curves. I discuss results for the inferred intrinsic correlation structures of the optical-NIR SN Ia light curves and the host galaxy dust distribution captured by the hierarchical model. The continued observation and analysis of Type Ia SN in the optical and near infrared is important for improving their utility as precise and accurate cosmological distance indicators.

The 1.4 GHZ light curve of GRB 970508

NARCIS (Netherlands)

Galama, TJ; Wijers, RAMJ; Groot, PJ; Strom, RG; De Bruyn, AG; Kouveliotou, C; Robinson, CR; van Paradus, J

1998-01-01

We report on Westerbork 1.4 GHz radio observations of the radio counterpart to gamma-ray burst GRB 970508, between 0.80 and 138 days after this event. The 1.4 GHz light curve shows a transition from optically thick to thin emission between 39 and 54 days after the event. We derive the slope p of the

Unification of binary star ephemeris solutions

International Nuclear Information System (INIS)

Wilson, R. E.; Van Hamme, W.

2014-01-01

Time-related binary system characteristics such as orbital period, its rate of change, apsidal motion, and variable light-time delay due to a third body, are measured in two ways that can be mutually complementary. The older way is via eclipse timings, while ephemerides by simultaneous whole light and velocity curve analysis have appeared recently. Each has its advantages, for example, eclipse timings typically cover relatively long time spans while whole curves often have densely packed data within specific intervals and allow access to systemic properties that carry additional timing information. Synthesis of the two information sources can be realized in a one step process that combines several data types, with automated weighting based on their standard deviations. Simultaneous light-velocity-timing solutions treat parameters of apsidal motion and the light-time effect coherently with those of period and period change, allow the phenomena to interact iteratively, and produce parameter standard errors based on the quantity and precision of the curves and timings. The logic and mathematics of the unification algorithm are given, including computation of theoretical conjunction times as needed for generation of eclipse timing residuals. Automated determination of eclipse type, recovery from inaccurate starting ephemerides, and automated data weighting are also covered. Computational examples are given for three timing-related cases—steady period change (XY Bootis), apsidal motion (V526 Sagittarii), and the light-time effect due to a binary's reflex motion in a triple system (AR Aurigae). Solutions for all combinations of radial velocity, light curve, and eclipse timing input show consistent results, with a few minor exceptions.

The Physics of Type Ia Supernova Light Curves. I. Analytic Results and Time Dependence

International Nuclear Information System (INIS)

Pinto, Philip A.; Eastman, Ronald G.

2000-01-01

We develop an analytic solution of the radiation transport problem for Type Ia supernovae (SNe Ia) and show that it reproduces bolometric light curves produced by more detailed calculations under the assumption of a constant-extinction coefficient. This model is used to derive the thermal conditions in the interior of SNe Ia and to study the sensitivity of light curves to various properties of the underlying supernova explosions. Although the model is limited by simplifying assumptions, it is adequate for demonstrating that the relationship between SNe Ia maximum-light luminosity and rate of decline is most easily explained if SNe Ia span a range in mass. The analytic model is also used to examine the size of various terms in the transport equation under conditions appropriate to maximum light. For instance, the Eulerian and advective time derivatives are each shown to be of the same order of magnitude as other order v/c terms in the transport equation. We conclude that a fully time-dependent solution to the transport problem is needed in order to compute SNe Ia light curves and spectra accurate enough to distinguish subtle differences of various explosion models. (c) 2000 The American Astronomical Society

Practicing for 2023 and 2024: What the AAS Solar Eclipse Task Force Learned from the "Great American Eclipse" of 2017

Science.gov (United States)

Fienberg, R. T.; Speck, A. K.; Habbal, S. R.

2017-12-01

More than three years ahead of the "Great American Eclipse" of August 2017, the American Astronomical Society formed the AAS Solar Eclipse Task Force to function as a think tank, coordinating body, and communication gateway to the vast resources available about the 2017 eclipse and solar eclipses more generally. The task force included professional and amateur astronomers, formal and informal educators, and science journalists; many had experienced total solar eclipses before, and others would experience their first totality in August 2017. The AAS task force secured funding from the AAS Council, the National Science Foundation, and NASA. These resources were used mainly for three purposes: (1) to build a website that contains basic information about solar eclipses, safe viewing practices, and eclipse imaging and video, along with resources for educators and the media and a searchable map of eclipse-related events and activities, with links to other authoritative websites with more detailed information; (2) to solicit, receive, evaluate, and fund proposals for mini-grants to support eclipse-related education and public outreach to underrepresented groups both inside and outside the path of totality; and (3) to organize a series of multidisciplinary workshops across the country to prepare communities for the eclipse and to facilitate collaborations between astronomers, meteorologists, school administrators, and transporation and emergency-management professionals. Most importantly, the AAS Solar Eclipse Task Force focused on developing and disseminating appropriate eclipse safety information. The AAS and NASA jointly developed safety messaging that won the endorsement of the American Academies of Opthalmology and Optometry. In the weeks immediately preceding the eclipse, it became clear that the marketplace was being flooded by counterfeit eclipse glasses and solar viewers, leading to a last minute change in our communication strategy. In this talk, we'll review the

LATE-TIME LIGHT CURVES OF TYPE II SUPERNOVAE: PHYSICAL PROPERTIES OF SUPERNOVAE AND THEIR ENVIRONMENT

Energy Technology Data Exchange (ETDEWEB)

Otsuka, Masaaki; Meixner, Margaret; Panagia, Nino [Space Telescope Science Institute, 3700 San Martin Dr., Baltimore, MD 21218 (United States); Fabbri, Joanna; Barlow, Michael J.; Wesson, Roger [Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT (United Kingdom); Clayton, Geoffrey C.; Andrews, Jennifer E. [Department of Physics and Astronomy, Louisiana State University, Baton Rouge, LA 70803 (United States); Gallagher, Joseph S. [Department of Mathematics, Physics, and Computer Science, Raymond Walters College, 9555 Plain field Rd., Blue Ash, OH 45236 (United States); Sugerman, Ben E. K. [Department of Physics and Astronomy, Goucher College, 1021 Dulaney Valley Road, Baltimore, MD 21204 (United States); Ercolano, Barbara [Universitaets-Sternwarte Muenchen, Scheinerstr. 1, 81679 Muenchen (Germany); Welch, Douglas, E-mail: otsuka@stsci.edu, E-mail: otsuka@asiaa.sinica.edu.tw [Department of Physics and Astronomy, McMaster University, Hamilton, Ontario L8S 4M1 (Canada)

2012-01-01

We present BVRIJHK-band photometry of six core-collapse supernovae, SNe 1999bw, 2002hh, 2003gd, 2004et, 2005cs, and 2006bc, measured at late epochs (>2 yr) based on the Hubble Space Telescope (HST), and the Gemini North, and WIYN telescopes. We also show the JHK light curves of supernova impostor SN 2008S up to day 575 because it was serendipitously in our SN 2002hh field of view. Of our 43 HST observations in total, 36 observations are successful in detecting the light from the SNe alone and measuring magnitudes of all the targets. HST observations show a resolved scattered light echo around SN 2003gd at day 1520 and around SN 2002hh at day 1717. Our Gemini and WIYN observations detected SNe 2002hh and 2004et as well. Combining our data with previously published data, we show VRIJHK-band light curves and estimate decline magnitude rates at each band in four different phases. Our prior work on these light curves and other data indicate that dust is forming in our targets from days {approx}300 to 400, supporting SN dust formation theory. In this paper we focus on other physical properties derived from late-time light curves. We estimate {sup 56}Ni masses for our targets (0.5-14 Multiplication-Sign 10{sup -2} M{sub Sun }) from the bolometric light curve of each of days {approx}150-300 using SN 1987A as a standard (7.5 Multiplication-Sign 10{sup -2} M{sub Sun }). The flattening or sometimes increasing fluxes in the late-time light curves of SNe 2002hh, 2003gd, 2004et, and 2006bc indicate the presence of light echoes. We estimate the circumstellar hydrogen density of the material causing the light echo and find that SN 2002hh is surrounded by relatively dense materials (n(H) >400 cm{sup -3}) and SNe 2003gd and 2004et have densities more typical of the interstellar medium ({approx}1 cm{sup -3}). We analyze the sample as a whole in the context of physical properties derived in prior work. The {sup 56}Ni mass appears well correlated with progenitor mass with a slope of 0

Spectrum of EY Orionis at the secondary eclipse

International Nuclear Information System (INIS)

Ismailov, N.Z.

1987-01-01

The results of spectral observations of the binary system EY orions at the secondary eclipse are presented. Some peculiar properties in the linear spectrum of the star have been discovered. The spectrum of the second component is not observed. The rotational velocity of the visible component is equal to 150 ± 30 km/s. During the phases 0.52-0.58, during approximately 1 d the radial velocities deviate from the radial velocity curve. According to the character of its spectrum the system EY Orions is similar to typical Orion variables

A New Orbit for the Eclipsing Binary V577 Oph

Energy Technology Data Exchange (ETDEWEB)

Jeffery, Elizabeth J. [Physics Department, California Polytechnic State University, San Luis Obispo, CA 93407 (United States); Barnes, Thomas G. III; Montemayor, Thomas J. [The University of Texas at Austin, McDonald Observatory, 1 University Station, C1402, Austin, TX 78712-0259 (United States); Skillen, Ian, E-mail: ejjeffer@calpoly.edu, E-mail: tgb@astro.as.utexas.edu, E-mail: tm@astro.as.utexas.edu, E-mail: wji@ing.iac.es [Isaac Newton Group, Apartado de Correos 321, E-38700 Santa Cruz de La Palma, Canary Islands (Spain)

2017-09-01

Pulsating stars in eclipsing binary systems are unique objects for providing constraints on stellar models. To fully leverage the information available from the binary system, full orbital radial velocity curves must be obtained. We report 23 radial velocities for components of the eclipsing binary V577 Oph, whose primary star is a δ Sct variable. The velocities cover a nearly complete orbit and a time base of 20 years. We computed orbital elements for the binary and compared them to the ephemeris computed by Creevey et al. The comparison shows marginally different results. In particular, a change in the systemic velocity by −2 km s{sup −1} is suggested by our results. We compare this systemic velocity difference to that expected due to reflex motion of the binary in response to the third body in the system. The systemic velocity difference is consistent with reflex motion, given our mass determination for the eclipsing binary and the orbital parameters determined by Volkov and Volkova for the three-body orbit. We see no evidence for the third body in our spectra, but we do see strong interstellar Na D lines that are consistent in strength with the direction and expected distance of V577 Oph.

A New Orbit for the Eclipsing Binary V577 Oph

Science.gov (United States)

Jeffery, Elizabeth J.; Barnes, Thomas G., III; Skillen, Ian; Montemayor, Thomas J.

2017-09-01

Pulsating stars in eclipsing binary systems are unique objects for providing constraints on stellar models. To fully leverage the information available from the binary system, full orbital radial velocity curves must be obtained. We report 23 radial velocities for components of the eclipsing binary V577 Oph, whose primary star is a δ Sct variable. The velocities cover a nearly complete orbit and a time base of 20 years. We computed orbital elements for the binary and compared them to the ephemeris computed by Creevey et al. The comparison shows marginally different results. In particular, a change in the systemic velocity by -2 km s-1 is suggested by our results. We compare this systemic velocity difference to that expected due to reflex motion of the binary in response to the third body in the system. The systemic velocity difference is consistent with reflex motion, given our mass determination for the eclipsing binary and the orbital parameters determined by Volkov & Volkova for the three-body orbit. We see no evidence for the third body in our spectra, but we do see strong interstellar Na D lines that are consistent in strength with the direction and expected distance of V577 Oph.

UBVRIz LIGHT CURVES OF 51 TYPE II SUPERNOVAE

International Nuclear Information System (INIS)

Galbany, Lluis; Hamuy, Mario; Jaeger, Thomas de; Moraga, Tania; González-Gaitán, Santiago; Gutiérrez, Claudia P.; Phillips, Mark M.; Morrell, Nidia I.; Thomas-Osip, Joanna; Suntzeff, Nicholas B.; Maza, José; González, Luis; Antezana, Roberto; Wishnjewski, Marina; Krisciunas, Kevin; Krzeminski, Wojtek; McCarthy, Patrick; Anderson, Joseph P.; Stritzinger, Maximilian; Folatelli, Gastón

2016-01-01

We present a compilation of UBVRIz light curves of 51 type II supernovae discovered during the course of four different surveys during 1986–2003: the Cerro Tololo Supernova Survey, the Calán/Tololo Supernova Program (C and T), the Supernova Optical and Infrared Survey (SOIRS), and the Carnegie Type II Supernova Survey (CATS). The photometry is based on template-subtracted images to eliminate any potential host galaxy light contamination, and calibrated from foreground stars. This work presents these photometric data, studies the color evolution using different bands, and explores the relation between the magnitude at maximum brightness and the brightness decline parameter (s) from maximum light through the end of the recombination phase. This parameter is found to be shallower for redder bands and appears to have the best correlation in the B band. In addition, it also correlates with the plateau duration, being shorter (longer) for larger (smaller) s values

UBVRIz LIGHT CURVES OF 51 TYPE II SUPERNOVAE

Energy Technology Data Exchange (ETDEWEB)

Galbany, Lluis; Hamuy, Mario; Jaeger, Thomas de; Moraga, Tania; González-Gaitán, Santiago; Gutiérrez, Claudia P. [Millennium Institute of Astrophysics, Universidad de Chile (Chile); Phillips, Mark M.; Morrell, Nidia I.; Thomas-Osip, Joanna [Carnegie Observatories, Las Campanas Observatory, Casilla 60, La Serena (Chile); Suntzeff, Nicholas B. [Department of Physics and Astronomy, Texas A and M University, College Station, TX 77843 (United States); Maza, José; González, Luis; Antezana, Roberto; Wishnjewski, Marina [Departamento de Astronomía, Universidad de Chile, Camino El Observatorio 1515, Las Condes, Santiago (Chile); Krisciunas, Kevin [George P. and Cynthia Woods Mitchell Institute for Fundamental Physics and Astronomy, Texas A. and M. University, Department of Physics and Astronomy, 4242 TAMU, College Station, TX 77843 (United States); Krzeminski, Wojtek [N. Copernicus Astronomical Center, ul. Bartycka 18, 00-716 Warszawa (Poland); McCarthy, Patrick [The Observatories of the Carnegie Institution for Science, 813 Santa Barbara Street, Pasadena, CA 91101 (United States); Anderson, Joseph P. [European Southern Observatory, Alonso de Cordova 3107, Vitacura, Casilla 19001, Santiago (Chile); Stritzinger, Maximilian [Department of Physics and Astronomy, Aarhus University (Denmark); Folatelli, Gastón, E-mail: lgalbany@das.uchile.cl [Instituto de Astrofísica de La Plata (IALP, CONICET) (Argentina); and others

2016-02-15

We present a compilation of UBVRIz light curves of 51 type II supernovae discovered during the course of four different surveys during 1986–2003: the Cerro Tololo Supernova Survey, the Calán/Tololo Supernova Program (C and T), the Supernova Optical and Infrared Survey (SOIRS), and the Carnegie Type II Supernova Survey (CATS). The photometry is based on template-subtracted images to eliminate any potential host galaxy light contamination, and calibrated from foreground stars. This work presents these photometric data, studies the color evolution using different bands, and explores the relation between the magnitude at maximum brightness and the brightness decline parameter (s) from maximum light through the end of the recombination phase. This parameter is found to be shallower for redder bands and appears to have the best correlation in the B band. In addition, it also correlates with the plateau duration, being shorter (longer) for larger (smaller) s values.

Magnetic Activity and Period Variation Studies of the Short-period Eclipsing Binaries. II. V1101 Her, AD Phe, and NSV 455 (J011636.15-394955.7)

Science.gov (United States)

Pi, Qing-feng; Zhang, Li-yun; Bi, Shao-lan; Han, Xianming L.; Wang, Dai-mei; Lu, Hong-peng

2017-12-01

In this paper, we present new BVRI light curves of short-period contact eclipsing binaries V1101 Her and AD Phe from our observations carried out from 2014 to 2015 using the SARA KP and SARA CT telescopes. There is an eclipsing binary located at α(2000) = 01h16m36.ˢ15 and δ(2000) = -39°49‧55.″7 in the field of view of AD Phe. We derived an updated ephemeris and found there a cyclic variation overlaying a continuous period increase (V1101 Her) and decrease (AD Phe). This kind of cyclic variation may be attributed to the light time effect via the presence of the third body or magnetic activity cycle. The orbital period increase suggests that V1101 Her is undergoing a mass-transfer from the primary to the secondary component (dM 1/dt = 2.64(±0.11) × 10-6 M ⊙ yr-1) with the third body (P 3 = 13.9(±1.9) years), or 2.81(±0.07) × 10-6 M ⊙ yr-1 for an increase andmagnetic cycle (12.4(±0.5) years). The long-term period decrease suggests that AD Phe is undergoing a mass-transfer from the secondary component to the primary component at a rate of -8.04(±0.09) × 10-8 M ⊙ yr-1 for a period decrease and the third body (P 3 = 56.2(±0.8) years), or -7.11(±0.04) × 10-8 M ⊙ yr-1 for a decrease and magnetic cycle (50.3(±0.5) years). We determined their orbital and geometrical parameters. For AD Phe, we simultaneously analyzed our BVRI light curves and the spectroscopic observations obtained by Duerbeck & Rucinski. The spectral type of V1101 Her was classified as G0 ± 2V by LAMOST stellar spectra survey. The asymmetry of the R-band light curve of AD Phe obtained by McFarlane & Hilditch in 1987 is explained by a cool spot on the primary component.

Effects of March 20, 2015, partial (~50% solar eclipse on meteorological parameters in the urban area of Naples (Italy

Directory of Open Access Journals (Sweden)

Nicola Scafetta

2016-02-01

Full Text Available During the partial (~50% solar eclipse occurred on March 20, 2015, morning, various meteorological parameters were monitored to study their evolution above the urban area of Naples, central Italy. The experimental conditions were optimal because of the clear sky situation all over Italy, and in Naples in particular. The eclipse last about 2 hours between 9:25:06 (UT+1, local Italian time and 11:43:09 (local Italian time, UT+1. From the observation site, the incoming solar radiation diminished by about 50% at the eclipse peak at 10:32:18 (local Italian time, UT+1, as expected. On the contrary, the UV radiation diminished significantly less, about 25%. This frequency response was likely due to Rayleigh scattering. It suggests that about 50% of the UV radiation reaching the surface was direct light and 50% scattered light. During the eclipse, the urban surface temperature and humidity values stayed almost constant instead of increasing and decreasing, respectively, as predicted by their daily cycle. This result was used to estimate that the average emissivity of the city of Naples is about f = 0.86. The wind speed decreased significantly during the event while the atmospheric pressure stayed constant to decrease only after the eclipse. Finally, we propose a simple empirical method to approximately estimate the cooling effect of an eclipse, which meteorologists could use to correct the temperature model forecast that normally ignores the occurrence of an eclipse. Consistency of these results with the literature and its importance is briefly discussed.

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

Science.gov (United States)

Torres, Guillermo; Fressin, Francois; Batalha, Natalie M.; Borucki, William J.; Brown, Timothy M.; Bryson, Stephen T.; Buchhave, Lars A.; Charbonneau, David; Ciardi, David R.; Dunham, Edward W.;

Student artistry sparks eclipse excitement on Maui: NSO/DKIST EPO for the 2016 Partial Solar Eclipse

Science.gov (United States)

Schad, Thomas A.; Penn, Matthew J.; Armstrong, James

2016-05-01

Local creativity and artistry is a powerful resource that enhances education programs and helps us generate excitement for science within our communities. In celebration of the 2016 Solar Eclipse, the National Solar Observatory (NSO) and its Daniel K Inouye Solar Telescope (DKIST) project were pleased to engage with students across Maui County, Hawai`i, via the 2016 Maui Eclipse Art Contest. With the help of the Maui Economic Development Board and the University of Hawai'is Institute for Astronomy, we solicited art entries from all K-12 schools in Maui County approximately 6 months prior to the eclipse. Along with divisional prizes, a grand prize was selected by a panel of local judges, which was subsequently printed on 25,000 solar eclipse viewing glasses and distributed to all Maui students. We found that the impact of a locally-sourced glasses design cannot be understated. Overall, the success of this program relied upon reaching out to individual teachers, supplying educational flyers to all schools, and visiting classrooms. On the day of the eclipse, all of the art entries were prominently displayed during a community eclipse viewing event at Kalama Beach Park in Kihei, HI, that was co-hosted by NSO and the Maui Science Center. This eclipse art contest was integral to making local connections to help promote science education on Maui, and we suggest that it could be adapted to the solar community's EPO activities for the upcoming 2017 Great American Solar Eclipse.

REFINED NEUTRON STAR MASS DETERMINATIONS FOR SIX ECLIPSING X-RAY PULSAR BINARIES

International Nuclear Information System (INIS)

Rawls, Meredith L.; Orosz, Jerome A.; McClintock, Jeffrey E.; Torres, Manuel A. P.; Bailyn, Charles D.; Buxton, Michelle M.

2011-01-01

We present an improved method for determining the mass of neutron stars in eclipsing X-ray pulsar binaries and apply the method to six systems, namely, Vela X-1, 4U 1538-52, SMC X-1, LMC X-4, Cen X-3, and Her X-1. In previous studies to determine neutron star mass, the X-ray eclipse duration has been approximated analytically by assuming that the companion star is spherical with an effective Roche lobe radius. We use a numerical code based on Roche geometry with various optimizers to analyze the published data for these systems, which we supplement with new spectroscopic and photometric data for 4U 1538-52. This allows us to model the eclipse duration more accurately and thus calculate an improved value for the neutron star mass. The derived neutron star mass also depends on the assumed Roche lobe filling factor β of the companion star, where β = 1 indicates a completely filled Roche lobe. In previous work a range of β between 0.9 and 1.0 was usually adopted. We use optical ellipsoidal light-curve data to constrain β. We find neutron star masses of 1.77 ± 0.08 M sun for Vela X-1, 0.87 ± 0.07 M sun for 4U 1538-52 (eccentric orbit), 1.00 ± 0.10 M sun for 4U 1538-52 (circular orbit), 1.04 ± 0.09 M sun for SMC X-1, 1.29 ± 0.05 M sun for LMC X-4, 1.49 ± 0.08 M sun for Cen X-3, and 1.07 ± 0.36 M sun for Her X-1. We discuss the limits of the approximations that were used to derive the earlier mass determinations, and we comment on the implications our new masses have for observationally refining the upper and lower bounds of the neutron star mass distribution.

Preparation of Kepler light curves for asteroseismic analyses

DEFF Research Database (Denmark)

García, R.A.; Hekker, Saskia; Stello, Dennis

2011-01-01

The Kepler mission is providing photometric data of exquisite quality for the asteroseismic study of different classes of pulsating stars. These analyses place particular demands on the pre-processing of the data, over a range of time-scales from minutes to months. Here, we describe processing...... procedures developed by the Kepler Asteroseismic Science Consortium to prepare light curves that are optimized for the asteroseismic study of solar-like oscillating stars in which outliers, jumps and drifts are corrected....

Effect of solar eclipse on microbes

Directory of Open Access Journals (Sweden)

Amrita Shriyan

2011-01-01

Full Text Available Objective : A solar eclipse was observed in India on 15 th January, 2010. It was a total eclipse in some parts of the country, while it was a partial eclipse in other parts. Microorganisms play an important role in various phenomena on the earth. This study was undertaken to know the influence of solar eclipse on nature indirectly, by analyzing certain genotypic and phenotypic variations in prokaryotes and eukaryotes. Since yeast have similar gene expression as that of humans, investigations were pursued on Candida albicans. Hence the study of the effect of solar eclipse on cultures of Staphylococcus aureus, Klebsiella species, Escherichia coli, and C. albicans was performed in the laboratory. The effect of the total or partial eclipse on the microorganism isolated from clinical isolates was investigated during the time period from 11.15 am to 3.15 pm. Materials and Methods : Cultures of S. aureus, Klebsiella species, and E. coli colonies on nutrient agar slants and broth and C. albicans on Sabouraud′s dextrose agar plates and broth. Slants were exposed to sunlight during eclipse and exposure to normal sunlight at Mangalore, Dakshina Kannada district, Karnataka state, India. Results : There was significant change observed during exposure to normal sunlight and eclipse phase. Bacterial colonies showed difference in morphology on smear examination and sensitivity pattern during this study. One fungal species and three bacterial isolates were studied and changes were recorded. Fungal species showed a definite change in their morphology on exposure to sunlight during eclipse observed by stained smear examination from broth, plate, and slant. Conclusion : Present study concludes that blocking of the sun rays during eclipse does not harm prokaryotes and eukaryotes, instead promoted the progeny of predators in the race of better acclimatization and survival in the natural and changing environmental conditions.

New methods for deriving cometary secular light curves: C/1995 O1 (Hale-Bopp) revisited

Science.gov (United States)

Womack, Maria; Lastra, Nathan; Harrington, Olga; Curtis, Anthony; Wierzchos, Kacper; Ruffini, Nicholas; Charles, Mentzer; Rabson, David; Cox, Timothy; Rivera, Isabel; Micciche, Anthony

2017-10-01

We present an algorithm for reducing scatter and increasing precision in a comet light curve. As a demonstration, we processed apparent magnitudes of comet Hale-Bopp from 16 highly experienced observers (archived with the International Comet Quarterly), correcting for distance from Earth and phase angle. Different observers tend to agree on the difference in magnitudes of an object at different distances, but the magnitude reported by observer is shifted relative to that of another for an object at a fixed distance. We estimated the shifts using a self-consistent statistical approach, leading to a sharper light curve and improving the precision of the measured slopes. The final secular lightcurve for comet Hale-Bopp ranges from -7 au (pre-perihelion) to +8 au (post-perihelion) and is the best secular light curve produced to date for this “great” comet. We discuss Hale-Bopp’s lightcurve evolution and possibly related physical implications, and potential usefulness of this light curve for comparisons with other future bright comets. We also assess the appropriateness of using secular lightcurves to characterize dust production rates in Hale-Bopp and other dust-rich comets. M.W. acknowledges support from NSF grant AST-1615917.

CSI 2264: characterizing accretion-burst dominated light curves for young stars in NGC 2264

International Nuclear Information System (INIS)

Stauffer, John; Cody, Ann Marie; Rebull, Luisa; Carey, Sean; Baglin, Annie; Alencar, Silvia; Hillenbrand, Lynne A.; Carpenter, John; Findeisen, Krzysztof; Venuti, Laura; Bouvier, Jerome; Turner, Neal J.; Plavchan, Peter; Terebey, Susan; Morales-Calderón, María; Micela, Giusi; Flaccomio, Ettore; Song, Inseok; Gutermuth, Rob; Hartmann, Lee

2014-01-01

Based on more than four weeks of continuous high-cadence photometric monitoring of several hundred members of the young cluster NGC 2264 with two space telescopes, NASA's Spitzer and the CNES CoRoT (Convection, Rotation, and planetary Transits), we provide high-quality, multi-wavelength light curves for young stellar objects whose optical variability is dominated by short-duration flux bursts, which we infer are due to enhanced mass accretion rates. These light curves show many brief—several hours to one day—brightenings at optical and near-infrared wavelengths with amplitudes generally in the range of 5%-50% of the quiescent value. Typically, a dozen or more of these bursts occur in a 30 day period. We demonstrate that stars exhibiting this type of variability have large ultraviolet (UV) excesses and dominate the portion of the u – g versus g – r color-color diagram with the largest UV excesses. These stars also have large Hα equivalent widths, and either centrally peaked, lumpy Hα emission profiles or profiles with blueshifted absorption dips associated with disk or stellar winds. Light curves of this type have been predicted for stars whose accretion is dominated by Rayleigh-Taylor instabilities at the boundary between their magnetosphere and inner circumstellar disk, or where magneto-rotational instabilities modulate the accretion rate from the inner disk. Among the stars with the largest UV excesses or largest Hα equivalent widths, light curves with this type of variability greatly outnumber light curves with relatively smooth sinusoidal variations associated with long-lived hot spots. We provide quantitative statistics for the average duration and strength of the accretion bursts and for the fraction of the accretion luminosity associated with these bursts.

Multi-Band Light Curves from Two-Dimensional Simulations of Gamma-Ray Burst Afterglows

Science.gov (United States)

MacFadyen, Andrew

2010-01-01

The dynamics of gamma-ray burst outflows is inherently multi-dimensional. 1.) We present high resolution two-dimensional relativistic hydrodynamics simulations of GRBs in the afterglow phase using adaptive mesh refinement (AMR). Using standard synchrotron radiation models, we compute multi-band light curves, from the radio to X-ray, directly from the 2D hydrodynamics simulation data. We will present on-axis light curves for both constant density and wind media. We will also present off-axis light curves relevant for searches for orphan afterglows. We find that jet breaks are smoothed due to both off-axis viewing and wind media effects. 2.) Non-thermal radiation mechanisms in GRB afterglows require substantial magnetic field strengths. In turbulence driven by shear instabilities in relativistic magnetized gas, we demonstrate that magnetic field is naturally amplified to half a percent of the total energy (epsilon B = 0.005). We will show high resolution three dimensional relativistic MHD simulations of this process as well as particle in cell (PIC) simulations of mildly relativistic collisionless shocks.

Mg II Line Variation of 32 Cygni

Directory of Open Access Journals (Sweden)

Young Woon Kang

1992-12-01

Full Text Available The Mg II lines have been extracted from the IUE archival spectra of 32 Cygni to investigate the effect of the atmospheric eclipse. The UV light curve has been reduced from the continuum flux at the center wavelength of 2807.5 Å in the IUE spectra. The equivalent width of the Mg II k absoption line has been measured for each spectra. The results of the light variation and flux tracing of the absorption line at the vicinity of the primary eclipse confirmed the atmospheric eclipse. The atmospheric effect lasted until the phase 0.06 in the absorptin line tracing, while it lasted until the phase 0.02 in the UV light curve, respectively.

The Peculiar Light Curve of J1415+1320: A Case Study in Extreme Scattering Events

Science.gov (United States)

Vedantham, H. K.; Readhead, A. C. S.; Hovatta, T.; Koopmans, L. V. E.; Pearson, T. J.; Blandford, R. D.; Gurwell, M. A.; Lähteenmäki, A.; Max-Moerbeck, W.; Pavlidou, V.; Ravi, V.; Reeves, R. A.; Richards, J. L.; Tornikoski, M.; Zensus, J. A.

2017-08-01

The radio light curve of J1415+1320 (PKS 1413+135) shows time-symmetric and recurring U-shaped features across the centimeter-wave and millimeter-wave bands. The symmetry of these features points to lensing by an intervening object as the cause. U-shaped events in radio light curves in the centimeter-wave band have previously been attributed to Extreme scattering events (ESE). ESEs are thought to be the result of lensing by compact plasma structures in the Galactic interstellar medium, but the precise nature of these plasma structures remains unknown. Since the strength of a plasma lens evolves with wavelength λ as {λ }2, the presence of correlated variations at over a wide wavelength range casts doubt on the canonical ESE interpretation for J1415+1320. In this paper, we critically examine the evidence for plasma lensing in J1415+1320. We compute limits on the lensing strength and the associated free-free opacity of the putative plasma lenses. We compare the observed and model ESE light curves, and also derive a lower limit on the lens distance based on the effects of parallax due to the Earth’s orbit around the Sun. We conclude that plasma lensing is not a viable interpretation for J1415+1320's light curves and that symmetric U-shaped features in the radio light curves of extragalactic sources do not present prima facie evidence for ESEs. The methodology presented here is generic enough to be applicable to any plasma-lensing candidate.

DETERMINATION OF THE LIGHT CURVE OF THE ARTIFICIAL SATELLITE BY ITS ROTATION PATH AS PREPARATION TO THE INVERSE PROBLEM SOLUTION

OpenAIRE

Pavlenko, Daniil

2012-01-01

Developing the algorithm of estimation of the rotational parameters of the artificial satellite by its light curve, we face the necessity to compute test light curves for various initially given types of rotation and specific features of lighting of the satellite. In the present study the algorithm of creation of such light curves with the simulation method and the obtained result are described.

Use of supernovae light curves for testing the expansion hypothesis and other cosmological relations

International Nuclear Information System (INIS)

Rust, B.W.

1974-01-01

This thesis is primarily concerned with a test of the expansion hypothesis based on the relation Δt/sub obs/ = (1 + V/sub r//c)Δt/sub int/ where Δt/sub int/ is the time lapse characterizing some phenomenon in a distant galaxy, Δt/sub obs/ is the observed time lapse and V/sub r/ is the symbolic velocity of recession. If the red shift is a Doppler effect, the observed time lapse should be lengthened by the same factor as the wave length of the light. Many authors have suggested type I supernovae for such a test because of their great luminosity and the uniformity of their light curves, but apparently the test has heretofore never actually been performed. Thirty-six light curves were gathered from the literature and one (SN1971i) was measured. All of the light curves were reduced to a common (m/sub pg/) photometric system. The comparison time lapse, Δt/sub c/, was taken to be the time required for the brightness to fall from 0.5 m below peak to 2.5 m below peak. The straight line regression of Δt/sub c/ on V/sub r/ gives a correlation coefficient significant at the 93 percent level, and the simple static Euclidean hypothesis is rejected at that level. The regression line also deviates from the prediction of the classical expansion hypothesis. Better agreement was obtained using the chronogeometric theory of I. E. Segal ( []972 Astron. and Astrophys. 18, 143), but the scatter in the present data makes it impossible to distinguish between these alternate hypotheses at the 95 percent confidence level. The question of how many additional light curves would be needed to give definite tests is addressed. It is shown that at the present rate of supernova discoveries, only a few more years would be required to obtain the necessary data if light curves are systematically measured for the more distant supernovae. (Diss. Abstr. Int., B)

CfA3: 185 TYPE Ia SUPERNOVA LIGHT CURVES FROM THE CfA

International Nuclear Information System (INIS)

Hicken, Malcolm; Challis, Peter; Kirshner, Robert P.; Bakos, Gaspar; Berlind, Perry; Brown, Warren R.; Caldwell, Nelson; Calkins, Mike; Cho, Richard; Contreras, Maria; Jha, Saurabh; Matheson, Tom; Modjaz, Maryam; Rest, Armin; Michael Wood-Vasey, W.; Barton, Elizabeth J.; Bragg, Ann; Briceno, Cesar; Ciupik, Larry; Dendy, Kristi-Concannon

2009-01-01

We present multiband photometry of 185 type-Ia supernovae (SNe Ia), with over 11,500 observations. These were acquired between 2001 and 2008 at the F. L. Whipple Observatory of the Harvard-Smithsonian Center for Astrophysics (CfA). This sample contains the largest number of homogeneously observed and reduced nearby SNe Ia (z ∼< 0.08) published to date. It more than doubles the nearby sample, bringing SN Ia cosmology to the point where systematic uncertainties dominate. Our natural system photometry has a precision of ∼<0.02 mag in BVRIr'i' and ∼<0.04 mag in U for points brighter than 17.5 mag. We also estimate a systematic uncertainty of 0.03 mag in our SN Ia standard system BVRIr'i' photometry and 0.07 mag for U. Comparisons of our standard system photometry with published SN Ia light curves and comparison stars, where available for the same SN, reveal agreement at the level of a few hundredths mag in most cases. We find that 1991bg-like SNe Ia are sufficiently distinct from other SNe Ia in their color and light-curve-shape/luminosity relation that they should be treated separately in light-curve/distance fitter training samples. The CfA3 sample will contribute to the development of better light-curve/distance fitters, particularly in the few dozen cases where near-infrared photometry has been obtained and, together, can help disentangle host-galaxy reddening from intrinsic supernova color, reducing the systematic uncertainty in SN Ia distances due to dust.

Ensemble Learning Method for Outlier Detection and its Application to Astronomical Light Curves

Science.gov (United States)

Nun, Isadora; Protopapas, Pavlos; Sim, Brandon; Chen, Wesley

2016-09-01

Outlier detection is necessary for automated data analysis, with specific applications spanning almost every domain from financial markets to epidemiology to fraud detection. We introduce a novel mixture of the experts outlier detection model, which uses a dynamically trained, weighted network of five distinct outlier detection methods. After dimensionality reduction, individual outlier detection methods score each data point for “outlierness” in this new feature space. Our model then uses dynamically trained parameters to weigh the scores of each method, allowing for a finalized outlier score. We find that the mixture of experts model performs, on average, better than any single expert model in identifying both artificially and manually picked outliers. This mixture model is applied to a data set of astronomical light curves, after dimensionality reduction via time series feature extraction. Our model was tested using three fields from the MACHO catalog and generated a list of anomalous candidates. We confirm that the outliers detected using this method belong to rare classes, like Novae, He-burning, and red giant stars; other outlier light curves identified have no available information associated with them. To elucidate their nature, we created a website containing the light-curve data and information about these objects. Users can attempt to classify the light curves, give conjectures about their identities, and sign up for follow up messages about the progress made on identifying these objects. This user submitted data can be used further train of our mixture of experts model. Our code is publicly available to all who are interested.

Marginalizing Instrument Systematics in HST WFC3 Transit Light Curves

Science.gov (United States)

Wakeford, H. R.; Sing, D. K.; Evans, T.; Deming, D.; Mandell, A.

2016-03-01

Hubble Space Telescope (HST) Wide Field Camera 3 (WFC3) infrared observations at 1.1-1.7 μm probe primarily the H2O absorption band at 1.4 μm, and have provided low-resolution transmission spectra for a wide range of exoplanets. We present the application of marginalization based on Gibson to analyze exoplanet transit light curves obtained from HST WFC3 to better determine important transit parameters such as Rp/R*, which are important for accurate detections of H2O. We approximate the evidence, often referred to as the marginal likelihood, for a grid of systematic models using the Akaike Information Criterion. We then calculate the evidence-based weight assigned to each systematic model and use the information from all tested models to calculate the final marginalized transit parameters for both the band-integrated and spectroscopic light curves to construct the transmission spectrum. We find that a majority of the highest weight models contain a correction for a linear trend in time as well as corrections related to HST orbital phase. We additionally test the dependence on the shift in spectral wavelength position over the course of the observations and find that spectroscopic wavelength shifts {δ }λ (λ ) best describe the associated systematic in the spectroscopic light curves for most targets while fast scan rate observations of bright targets require an additional level of processing to produce a robust transmission spectrum. The use of marginalization allows for transparent interpretation and understanding of the instrument and the impact of each systematic evaluated statistically for each data set, expanding the ability to make true and comprehensive comparisons between exoplanet atmospheres.

Eclipses and the Olympics

Science.gov (United States)

Pang, K. D.; Yau, K. K.

2000-12-01

Like returns of Halley's comet the Olympic games occur periodically, though not as regularly in antiquity. Dates were also imprecise due to the chaotic calendars in use. Reported sightings of comets and eclipses can be used with game dates to help fix ancient events. However some reported darkening of the sun, e.g., after Julius Caesar's murder in 44 BC, was due to volcanic eruptions. A red comet, visible in daylight, first appeared during the games that year. It was also seen from China and Korea (Pang, Sciences 31, 30). Phlegon's ``Olympiads" (2nd century) says that Christ's crucifixion was in the 4th year of the 202nd Olympiad (AD 29-33), when a total solar eclipse occurred in the 6th hour. Only the Nov. 24, AD 29 eclipse over Asia Minor can match that, and Joel's prophecy (Acts 2, 14-21) that ``the sun will be turned to darkness and moon to blood." However it conflicts with ``the first day of Passover," as recorded by Mathew, Mark and Luke, i.e., full moon in early spring. Humphreys and Waddington (Nature 306, 743) have suggested meteorological darkening and the April 3, AD 33 lunar eclipse instead. Schaefer has questioned the eclipse's visibility from Jerusalem (31.46N, 35.14E). The six computations he cited gave dissimilar answers due to the imprecise rates of the secular lunar acceleration, and lengthening of the day used (Q.Jl.R.astr.Soc. 31, 53). Lunar laser ranging has since fixed the former at -26"/cen2. Analysis of ancient Chinese solar eclipse records, e.g., the April 21, 899 BC and April 4, AD 368 ``double dawns" over Zheng, has given us a delta T (in sec) = 30t2, where t is centuries before 1800 (Pang, Yau and Chou, in ``Dynamics of Ice Age Earth: A Modern Perspective," 1998). Our computations show that the moon rose over Jerusalem, with 1/3 still in the umbra and the rest in penumbra. Holdover meteorological darkening with long absorption air mass could have help reddened the moon also. Finally the first ``eclipse season" (the Aug. 21 lunar, and

V773 Cas, QS Aql, AND BR Ind: ECLIPSING BINARIES AS PARTS OF MULTIPLE SYSTEMS

Energy Technology Data Exchange (ETDEWEB)

Zasche, P.; Juryšek, J.; Nemravová, J.; Wolf, M.; Korčáková, D. [Astronomical Institute, Charles University in Prague, Faculty of Mathematics and Physics, CZ-180 00, Praha 8, V Holešovičkách 2 (Czech Republic); Uhlař, R. [Private Observatory, Pohoří 71, CZ-254 01, Jílové u Prahy (Czech Republic); Svoboda, P. [Private Observatory, Výpustky 5, CZ-614 00, Brno (Czech Republic); Hoňková, K. [Variable Star and Exoplanet Section of Czech Astronomical Society, Vsetínská 941/78, CZ-757 01, Valašské Meziříčí (Czech Republic); Mašek, M.; Prouza, M. [Institute of Physics, The Czech Academy of Sciences, Na Slovance 1999/2, CZ-182 21, Praha (Czech Republic); Čechura, J.; Šlechta, M., E-mail: zasche@sirrah.troja.mff.cuni.cz [Astronomical Institute, The Czech Academy of Sciences, CZ-251 65, Ondřejov (Czech Republic)

2017-01-01

Eclipsing binaries remain crucial objects for our understanding of the universe. In particular, those that are components of multiple systems can help us solve the problem of the formation of these systems. Analysis of the radial velocities together with the light curve produced for the first time precise physical parameters of the components of the multiple systems V773 Cas, QS Aql, and BR Ind. Their visual orbits were also analyzed, which resulted in slightly improved orbital elements. What is typical for all these systems is that their most dominant source is the third distant component. The system V773 Cas consists of two similar G1-2V stars revolving in a circular orbit and a more distant component of the A3V type. Additionally, the improved value of parallax was calculated to be 17.6 mas. Analysis of QS Aql resulted in the following: the inner eclipsing pair is composed of B6V and F1V stars, and the third component is of about the B6 spectral type. The outer orbit has high eccentricity of about 0.95, and observations near its upcoming periastron passage between the years 2038 and 2040 are of high importance. Also, the parallax of the system was derived to be about 2.89 mas, moving the star much closer to the Sun than originally assumed. The system BR Ind was found to be a quadruple star consisting of two eclipsing K dwarfs orbiting each other with a period of 1.786 days; the distant component is a single-lined spectroscopic binary with an orbital period of about 6 days. Both pairs are moving around each other on their 148 year orbit.

Eclipse plugin development by example beginner's guide

CERN Document Server

Blewitt, Alex

2013-01-01

A Beginner's Guide following the ""by Example"" approach. There will be 5-8 major examples that will be used in the book to develop advanced plugins with the Eclipse IDE.This book is for Java developers who are familiar with Eclipse as a Java IDE and are interested in learning how to develop plug-ins for Eclipse. No prior knowledge of Eclipse plug-in development or OSGi is necessary, although you are expected to know how to create, run, and debug Java programs in Eclipse.

Revising the Model of Eclipsing Binary Stars for the Kepler Era

Science.gov (United States)

Prsa, Andrej

2010-01-01

The French-led mission CoRoT (Baglin et al. 2007) and NASA's Kepler mission (Borucki et al. 2007) have achieved unprecedented photometric accuracy, enabling us to glean stellar variability on scales that have yet to be understood. To employ the full power of eclipsing binary models requires substantial revision of the currently available codes such as WD (Wilson & Devinney 1971) or PHOEBE (Prsa & Zwitter 2005). One of the most important aspects of theoretical light curve computation is stellar surface discretization. Until now, surface elements were determined by equidistant partitioning along co-latitude and longitude; this scheme is inefficient and produces numerical artifacts when stellar distortion is significant (i.e. semi-detached and overcontact systems). In its place we propose a method that relies on equidistant partitioning along equipotentials. This way surface elements cover the stars most uniformly. We further propose two alternatives for the starting vertex of discretization: the stellar pole and the back radius. The partitioning method with both alternatives is explained in detail and differences from the original scheme are discussed.

The Carnegie Supernova Project I. Analysis of stripped-envelope supernova light curves

Science.gov (United States)

Taddia, F.; Stritzinger, M. D.; Bersten, M.; Baron, E.; Burns, C.; Contreras, C.; Holmbo, S.; Hsiao, E. Y.; Morrell, N.; Phillips, M. M.; Sollerman, J.; Suntzeff, N. B.

2018-02-01

Stripped-envelope (SE) supernovae (SNe) include H-poor (Type IIb), H-free (Type Ib), and He-free (Type Ic) events thought to be associated with the deaths of massive stars. The exact nature of their progenitors is a matter of debate with several lines of evidence pointing towards intermediate mass (MinitCarnegie Supernova Project (CSP-I) that are unparalleled in terms of photometric accuracy and wavelength range. Light-curve parameters are estimated through the fits of an analytical function and trends are searched for among the resulting fit parameters. Detailed inspection of the dataset suggests a tentative correlation between the peak absolute B-band magnitude and Δm15(B), while the post maximum light curves reveals a correlation between the late-time linear slope and Δm15. Making use of the full set of optical and near-IR photometry, combined with robust host-galaxy extinction corrections, comprehensive bolometric light curves are constructed and compared to both analytic and hydrodynamical models. This analysis finds consistent results among the two different modeling techniques and from the hydrodynamical models we obtained ejecta masses of 1.1-6.2M⊙, 56Ni masses of 0.03-0.35M⊙, and explosion energies (excluding two SNe Ic-BL) of 0.25-3.0 × 1051 erg. Our analysis indicates that adopting κ = 0.07 cm2 g-1 as the mean opacity serves to be a suitable assumption when comparing Arnett-model results to those obtained from hydrodynamical calculations. We also find that adopting He I and O I line velocities to infer the expansion velocity in He-rich and He-poor SNe, respectively, provides ejecta masses relatively similar to those obtained by using the Fe II line velocities, although the use of Fe II as a diagnostic does imply higher explosion energies. The inferred range of ejecta masses are compatible with intermediate mass (MZAMS ≤ 20M⊙) progenitor stars in binary systems for the majority of SE SNe. Furthermore, our hydrodynamical modeling of the

Kepler Eclipsing Binary Stars. I. Catalog and Principal Characterization of 1879 Eclipsing Binaries in the First Data Release

Science.gov (United States)

Prša, Andrej; Batalha, Natalie; Slawson, Robert W.; Doyle, Laurance R.; Welsh, William F.; Orosz, Jerome A.; Seager, Sara; Rucker, Michael; Mjaseth, Kimberly; Engle, Scott G.; Conroy, Kyle; Jenkins, Jon; Caldwell, Douglas; Koch, David; Borucki, William

2011-03-01

The Kepler space mission is devoted to finding Earth-size planets orbiting other stars in their habitable zones. Its large, 105 deg2 field of view features over 156,000 stars that are observed continuously to detect and characterize planet transits. Yet, this high-precision instrument holds great promise for other types of objects as well. Here we present a comprehensive catalog of eclipsing binary stars observed by Kepler in the first 44 days of operation, the data being publicly available through MAST as of 2010 June 15. The catalog contains 1879 unique objects. For each object, we provide its Kepler ID (KID), ephemeris (BJD0, P 0), morphology type, physical parameters (T eff, log g, E(B - V)), the estimate of third light contamination (crowding), and principal parameters (T 2/T 1, q, fillout factor, and sin i for overcontacts, and T 2/T 1, (R 1 + R 2)/a, esin ω, ecos ω, and sin i for detached binaries). We present statistics based on the determined periods and measure the average occurrence rate of eclipsing binaries to be ~1.2% across the Kepler field. We further discuss the distribution of binaries as a function of galactic latitude and thoroughly explain the application of artificial intelligence to obtain principal parameters in a matter of seconds for the whole sample. The catalog was envisioned to serve as a bridge between the now public Kepler data and the scientific community interested in eclipsing binary stars.

KEPLER ECLIPSING BINARY STARS. I. CATALOG AND PRINCIPAL CHARACTERIZATION OF 1879 ECLIPSING BINARIES IN THE FIRST DATA RELEASE

International Nuclear Information System (INIS)

Prsa, Andrej; Engle, Scott G.; Conroy, Kyle; Batalha, Natalie; Rucker, Michael; Mjaseth, Kimberly; Slawson, Robert W.; Doyle, Laurance R.; Welsh, William F.; Orosz, Jerome A.; Seager, Sara; Jenkins, Jon; Caldwell, Douglas; Koch, David; Borucki, William

2011-01-01

The Kepler space mission is devoted to finding Earth-size planets orbiting other stars in their habitable zones. Its large, 105 deg 2 field of view features over 156,000 stars that are observed continuously to detect and characterize planet transits. Yet, this high-precision instrument holds great promise for other types of objects as well. Here we present a comprehensive catalog of eclipsing binary stars observed by Kepler in the first 44 days of operation, the data being publicly available through MAST as of 2010 June 15. The catalog contains 1879 unique objects. For each object, we provide its Kepler ID (KID), ephemeris (BJD 0 , P 0 ), morphology type, physical parameters (T eff , log g, E(B - V)), the estimate of third light contamination (crowding), and principal parameters (T 2 /T 1 , q, fillout factor, and sin i for overcontacts, and T 2 /T 1 , (R 1 + R 2 )/a, esin ω, ecos ω, and sin i for detached binaries). We present statistics based on the determined periods and measure the average occurrence rate of eclipsing binaries to be ∼1.2% across the Kepler field. We further discuss the distribution of binaries as a function of galactic latitude and thoroughly explain the application of artificial intelligence to obtain principal parameters in a matter of seconds for the whole sample. The catalog was envisioned to serve as a bridge between the now public Kepler data and the scientific community interested in eclipsing binary stars.

Testing the stationarity of white dwarf light-curves

International Nuclear Information System (INIS)

Molnar, L; Kollath, Z; Plachy, E; Paparo, M

2009-01-01

Long period white dwarfs show changes in their frequency spectra from one observing season to another, i.e. their light-curves cannot be considered as stationary multiperiodic variations on long timescales. However, due to the complex frequency spectra of these stars and the narrow frequency spacing, it is still unknown, what the shortest time scale is, where real physical modulation exists. We present tests on artificial data, resembling the observations, using time-frequency distributions (TFDs), Fourier-analysis and the analytical signal method.

A Comprehensive K2 and Ground-based Study of CRTS J035905.9+175034, an Eclipsing SU UMa System with a Large Mass Ratio

Science.gov (United States)

Littlefield, Colin; Garnavich, Peter; Kennedy, Mark; Szkody, Paula; Dai, Zhibin

2018-06-01

CRTS J035905.9+175034 is the first eclipsing SU UMa system for which a superoutburst has been observed by Kepler in the short-cadence mode. The light curve contains one superoutburst, eight normal outbursts (including a precursor to the superoutburst), and several minioutbursts that are present before—but not after—the superoutburst. The superoutburst began with a precursor normal outburst, and shortly after the peak of the precursor, the system developed large-amplitude superhumps that achieved their maximum amplitude after just three superhump cycles. The period excess of the initial superhump period relative to the orbital period implies a mass ratio of 0.281 ± 0.015, placing it marginally above most theoretical predictions of the highest-possible mass ratio for superhump formation. In addition, our analysis of the variations in eclipse width and depth, as well as the hot spot amplitudes, generally provides substantiation of the thermal-tidal instability model. The K2 data, in conjunction with our ground-based time-resolved spectroscopy and photometry from 2014 to 2016, allows us to determine many of the fundamental parameters of this system.

Circular polarimetry of EXO 033319-2554.2 - A new eclipsing AM Herculis star

Science.gov (United States)

Berriman, Graham; Smith, Paul S.

1988-01-01

This Letter presents circular polarimetry that unequivocally identifies EXO 033319-2554.2 as only the third eclipsing AM Her star and brings the total number of AM Her stars now identified to 14. The orbital period is 126.4 minutes, as previously reported, and defines a new short-period edge to the period gap seen in all classes of cataclysmic variable stars. EXO 033319-2554.2 shows 2.5 mag deep eclipses of the predominantly accreting magnetic pole on the white dwarf. Before the eclipse, the pole rotates into the line of sight and shows white-light circular polarization, due to cyclotron radiation, that reaches values as high as 10 percent. There is some evidence that the second pole is emitting cyclotron radiation too. How high time resolution photometry, linear polarimetry, and spectroscopy will be of great value in understanding this system.

Report about the Solar Eclipse on August 11, 1999

Science.gov (United States)

1999-08-01

from the area south of the building. Several telescopes were set up among the trees and on the adjoining field (just harvested). Clouds and Holes It was an unusual solar eclipse experience. Heavy clouds were passing by with sudden rainshowers, but fortunately there were also some holes with blue sky in between. While much of the first partial phase was visible through these, some really heavy clouds moved in a few minutes before the total phase, when the light had begun to fade. They drifted slowly - too slowly! - towards the east and the corona was never seen from the ESO HQ site. From here, the view towards the eclipsed Sun only cleared at the very instant of the second "diamond ring" phenomenon. This was beautiful, however, and evidently took most of the photographers by surprise, so very few, if any, photos were made of this memorable moment. Temperature Curve by Benoit Pirenne Temperature Curve on August 11 [JPEG: 646 x 395 pix - 35k] Measured by Benoit Pirenne - see also his meteorological webpage Nevertheless, the entire experience was fantastic - there were all the expected effects, the darkness, the cool air, the wind and the silence. It was very impressive indeed! And it was certainly a unique day in ESO history! Carolyn Collins Petersen from "Sky & Telescope" participated in the conference at ESO in the days before and watched the eclipse from the "Bürgerplatz" in Garching, about 1.5 km south of the ESO HQ. She managed to see part of the totality phase and filed some dramatic reports at the S&T Eclipse Expedition website. They describe very well the feelings of those in this area! Eclipse Photos Several members of the ESO staff went elsewhere and had more luck with the weather, especially at the moment of totality. Below are some of their impressive pictures. Eclipse Photo by Philippe Duhoux First "Diamond Ring" [JPEG: 400 x 292 pix - 34k] [JPEG: 800 x 583 pix - 144k] [JPEG: 2531 x 1846 pix - 1.3M] Eclipse Photo by Philippe Duhoux Totality [JPEG: 400 x 306

ACCURATE MASSES FOR THE PRIMARY AND SECONDARY IN THE ECLIPSING WHITE DWARF BINARY NLTT 11748

International Nuclear Information System (INIS)

Kilic, Mukremin; Brown, Warren R.; Kenyon, S. J.; Allende Prieto, Carlos; Agueeros, M. A.; Camilo, Fernando

2010-01-01

We measure the radial velocity curve of the eclipsing detached white dwarf binary NLTT 11748. The primary exhibits velocity variations with a semi-amplitude of 273 km s -1 and an orbital period of 5.641 hr. We do not detect any spectral features from the secondary star or any spectral changes during the secondary eclipse. We use our composite spectrum to constrain the temperature and surface gravity of the primary to be T eff = 8690 ± 140 K and log g = 6.54 ± 0.05, which correspond to a mass of 0.18 M sun . For an inclination angle of 89. 0 9 derived from the eclipse modeling, the mass function requires a 0.76 M sun companion. The merger time for the system is 7.2 Gyr. However, due to the extreme mass ratio of 0.24, the binary will most likely create an AM CVn system instead of a merger.

Human Adolescent Phase Response Curves to Bright White Light.

Science.gov (United States)

Crowley, Stephanie J; Eastman, Charmane I

2017-08-01

Older adolescents are particularly vulnerable to circadian misalignment and sleep restriction, primarily due to early school start times. Light can shift the circadian system and could help attenuate circadian misalignment; however, a phase response curve (PRC) to determine the optimal time for receiving light and avoiding light is not available for adolescents. We constructed light PRCs for late pubertal to postpubertal adolescents aged 14 to 17 years. Participants completed 2 counterbalanced 5-day laboratory sessions after 8 or 9 days of scheduled sleep at home. Each session included phase assessments to measure the dim light melatonin onset (DLMO) before and after 3 days of free-running through an ultradian light-dark (wake-sleep) cycle (2 h dim [~20 lux] light, 2 h dark). In one session, intermittent bright white light (~5000 lux; four 20-min exposures) was alternated with 10 min of dim room light once per day for 3 consecutive days. The time of light varied among participants to cover the 24-h day. For each individual, the phase shift to bright light was corrected for the free-run derived from the other laboratory session with no bright light. One PRC showed phase shifts in response to light start time relative to the DLMO and another relative to home sleep. Phase delay shifts occurred around the hours corresponding to home bedtime. Phase advances occurred during the hours surrounding wake time and later in the afternoon. The transition from delays to advances occurred at the midpoint of home sleep. The adolescent PRCs presented here provide a valuable tool to time bright light in adolescents.

Eclipsing binaries in open clusters

DEFF Research Database (Denmark)

Southworth, John; Clausen, J.V.

2006-01-01

Stars: fundamental parameters - Stars : binaries : eclipsing - Stars: Binaries: spectroscopic - Open clusters and ass. : general Udgivelsesdato: 5 August......Stars: fundamental parameters - Stars : binaries : eclipsing - Stars: Binaries: spectroscopic - Open clusters and ass. : general Udgivelsesdato: 5 August...

IMAGING STARSPOT EVOLUTION ON KEPLER TARGET KIC 5110407 USING LIGHT-CURVE INVERSION

International Nuclear Information System (INIS)

Roettenbacher, Rachael M.; Monnier, John D.; Harmon, Robert O.; Barclay, Thomas; Still, Martin

2013-01-01

The Kepler target KIC 5110407, a K-type star, shows strong quasi-periodic light curve fluctuations likely arising from the formation and decay of spots on the stellar surface rotating with a period of 3.4693 days. Using an established light-curve inversion algorithm, we study the evolution of the surface features based on Kepler space telescope light curves over a period of two years (with a gap of .25 years). At virtually all epochs, we detect at least one large spot group on the surface causing a 1%-10% flux modulation in the Kepler passband. By identifying and tracking spot groups over a range of inferred latitudes, we measured the surface differential rotation to be much smaller than that found for the Sun. We also searched for a correlation between the 17 stellar flares that occurred during our observations and the orientation of the dominant surface spot at the time of each flare. No statistically significant correlation was found except perhaps for the very brightest flares, suggesting that most flares are associated with regions devoid of spots or spots too small to be clearly discerned using our reconstruction technique. While we may see hints of long-term changes in the spot characteristics and flare statistics within our current data set, a longer baseline of observation will be needed to detect the existence of a magnetic cycle in KIC 5110407.

THE LICK AGN MONITORING PROJECT: PHOTOMETRIC LIGHT CURVES AND OPTICAL VARIABILITY CHARACTERISTICS

International Nuclear Information System (INIS)

Walsh, Jonelle L.; Bentz, Misty C.; Barth, Aaron J.; Minezaki, Takeo; Sakata, Yu; Yoshii, Yuzuru; Baliber, Nairn; Bennert, Vardha Nicola; Street, Rachel A.; Treu, Tommaso; Li Weidong; Filippenko, Alexei V.; Stern, Daniel; Brown, Timothy M.; Canalizo, Gabriela; Gates, Elinor L.; Greene, Jenny E.; Malkan, Matthew A.; Woo, Jong-Hak

2009-01-01

The Lick AGN Monitoring Project targeted 13 nearby Seyfert 1 galaxies with the intent of measuring the masses of their central black holes using reverberation mapping. The sample includes 12 galaxies selected to have black holes with masses roughly in the range 10 6 -10 7 M sun , as well as the well-studied active galactic nucleus (AGN) NGC 5548. In conjunction with a spectroscopic monitoring campaign, we obtained broadband B and V images on most nights from 2008 February through 2008 May. The imaging observations were carried out by four telescopes: the 0.76 m Katzman Automatic Imaging Telescope, the 2 m Multicolor Active Galactic Nuclei Monitoring telescope, the Palomar 60 inch (1.5 m) telescope, and the 0.80 m Tenagra II telescope. Having well-sampled light curves over the course of a few months is useful for obtaining the broad-line reverberation lag and black hole mass, and also allows us to examine the characteristics of the continuum variability. In this paper, we discuss the observational methods and the photometric measurements, and present the AGN continuum light curves. We measure various variability characteristics of each of the light curves. We do not detect any evidence for a time lag between the B- and V-band variations, and we do not find significant color variations for the AGNs in our sample.

An Outreach Project to Provide 2.1 Million Eclipse Glasses and Eclipse Information through 7,100 Libraries Nationwide

Science.gov (United States)

Fraknoi, Andrew; Schatz, Dennis; Dusenbery, Paul; Duncan, Douglas; Holland, Anne; Laconte, Keliann

2018-01-01

With support from the Moore Foundation, Google, the Research Corporation, and NASA, we were able to distribute about 2.1 million eclipse glasses and an extensive booklet of eclipse information and outreach suggestions to 7,100 public libraries throughout the nation. It appears that this project was the single largest program to provide glasses and eclipse information to the public in the U.S. The project using (and significantly enlarged) the existing STARNet network of libraries set up and maintained by the Space Science Institute. We were able to get glasses to a diverse set of institutions, including urban, rural, Native American, small town and large city libraries. In this poster, we will summarize the history of the project, the various components and how they worked together, and the results of a post survey of the librarians, which provided numbers, photographs, and impressions from the many libraries and their patrons. A map of the libraries involved is at www.starnetlibraries.org/2017eclipse/. The booklet of information that was sent to help train librarians in eclipse science and eclipse outreach can still be downloaded free at: http://www.starnetlibraries.org/EclipseGuide/.”

Spectroscopic and photometric study of the eclipsing interacting binary V495 Centauri

Science.gov (United States)

Rosales Guzmán, J. A.; Mennickent, R. E.; Djurašević, G.; Araya, I.; Curé, M.

2018-05-01

Double Periodic Variables (DPV) are among the new enigmas of semidetached eclipsing binaries. These are intermediate-mass binaries characterized by a long photometric period lasting on average 33 times the orbital period. We present a spectroscopic and photometric study of the DPV V495 Cen based on new high-resolution spectra and the ASAS V-band light curve. We have determined an improved orbital period of 33.492 ± 0.002 d and a long period of 1283 d. We find a cool evolved star of M2=0.91± 0.2 M_{⊙}, T2 = 6000 ± 250 K and R2=19.3 ± 0.5 R_{⊙} and a hot companion of M1= 5.76± 0.3 M_{⊙}, T1 = 16960 ± 400 K and R=4.5± 0.2 R_{⊙}. The mid-type B dwarf is surrounded by a concave and geometrically thick disc, of radial extension Rd= 40.2± 1.3 R_{⊙} contributing ˜11 per cent to the total luminosity of the system at the V band. The system is seen under inclination 84.8° ± 0.6° and it is at a distance d = 2092 ± 104.6 pc. The light-curve analysis suggests that the mass transfer stream impacts the external edge of the disc forming a hot region 11 per cent hotter than the surrounding disc material. The persistent V < R asymmetry of the Hα emission suggests the presence of a wind and the detection of a secondary absorption component in He I lines indicates a possible wind origin in the hotspot region.

The GO Cygni system: photoelectric observations and light curves analysis

International Nuclear Information System (INIS)

Rovithis, P.; Rovithis-Livaniou, H.; Niarchos, P.G.

1990-01-01

Photoelectric observations, in B and V, of the system GO Cygni obtained during 1985 at the Kryonerion Astronomical Station of the National Observatory of Greece are given. The corresponding light curves (typical β Lyrae) are analysed using Frequency Domain techniques. New photoelectric and absolute elements for the system are given, and its period was found to continue its increasing

Circular polarimetry of EXO 033319-2554.2 - a new eclipsing AM Herculis star

International Nuclear Information System (INIS)

Berriman, G.; Smith, P.S.

1988-01-01

This Letter presents circular polarimetry that unequivocally identifies EXO 033319-2554.2 as only the third eclipsing AM Her star and brings the total number of AM Her stars now identified to 14. The orbital period is 126.4 minutes, as previously reported, and defines a new short-period edge to the period gap seen in all classes of cataclysmic variable stars. EXO 033319-2554.2 shows 2.5 mag deep eclipses of the predominantly accreting magnetic pole on the white dwarf. Before the eclipse, the pole rotates into the line of sight and shows white-light circular polarization, due to cyclotron radiation, that reaches values as high as 10 percent. There is some evidence that the second pole is emitting cyclotron radiation too. How high time resolution photometry, linear polarimetry, and spectroscopy will be of great value in understanding this system. 17 references

A 12 MINUTE ORBITAL PERIOD DETACHED WHITE DWARF ECLIPSING BINARY

International Nuclear Information System (INIS)

Brown, Warren R.; Kilic, Mukremin; Kenyon, Scott J.; Hermes, J. J.; Winget, D. E.; Prieto, Carlos Allende

2011-01-01

We have discovered a detached pair of white dwarfs (WDs) with a 12.75 minute orbital period and a 1315 km s -1 radial velocity amplitude. We measure the full orbital parameters of the system using its light curve, which shows ellipsoidal variations, Doppler boosting, and primary and secondary eclipses. The primary is a 0.25 M sun tidally distorted helium WD, only the second tidally distorted WD known. The unseen secondary is a 0.55 M sun carbon-oxygen WD. The two WDs will come into contact in 0.9 Myr due to loss of energy and angular momentum via gravitational wave radiation. Upon contact the systems may merge (yielding a rapidly spinning massive WD), form a stable interacting binary, or possibly explode as an underluminous Type Ia supernova. The system currently has a gravitational wave strain of 10 -22 , about 10,000 times larger than the Hulse-Taylor pulsar; this system would be detected by the proposed Laser Interferometer Space Antenna gravitational wave mission in the first week of operation. This system's rapid change in orbital period will provide a fundamental test of general relativity.

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

Science.gov (United States)

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

2009-04-01

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

A Simple yet Accurate Method for Students to Determine Asteroid Rotation Periods from Fragmented Light Curve Data

Science.gov (United States)

Beare, R. A.

2008-01-01

Professional astronomers use specialized software not normally available to students to determine the rotation periods of asteroids from fragmented light curve data. This paper describes a simple yet accurate method based on Microsoft Excel[R] that enables students to find periods in asteroid light curve and other discontinuous time series data of…

2MASS J0516288+260738: Discovery of the first eclipsing late K + Brown dwarf binary system?

Science.gov (United States)

Schuh, S. L.; Handler, G.; Drechsel, H.; Hauschildt, P.; Dreizler, S.; Medupe, R.; Karl, C.; Napiwotzki, R.; Kim, S.-L.; Park, B.-G.; Wood, M. A.; Paparó, M.; Szeidl, B.; Virághalmy, G.; Zsuffa, D.; Hashimoto, O.; Kinugasa, K.; Taguchi, H.; Kambe, E.; Leibowitz, E.; Ibbetson, P.; Lipkin, Y.; Nagel, T.; Göhler, E.; Pretorius, M. L.

2003-11-01

We report the discovery of a new eclipsing system less than one arcminute south of the pulsating DB white dwarf KUV 05134+2605. The object could be identified with the point source 2MASS J0516288+260738 published by the Two Micron All Sky Survey. We present and discuss the first light curves as well as some additional colour and spectral information. The eclipse period of the system is 1.29 d, and, assuming this to be identical to the orbital period, the best light curve solution yields a mass ratio of m2/m1=0.11, a radius ratio of r2/r1~ 1 and an inclination of 74o. The spectral anaylsis results in a Teff=4200 K for the primary. On this basis, we suggest that the new system probably consists of a late K + Brown dwarf (which would imply a system considerably younger than ~0.01 Gyr to have r2/r1~ 1), and outline possible future observations. This paper uses observations made at the Bohyunsan Optical Astronomy Observatory of Korea Astronomy Observatory, at the South African Astronomical Observatory (SAAO), at the 0.9 m telescope at Kitt Peak National Observatory recommissioned by the Southeastern Association for Research in Astronomy (SARA), at Gunma Astronomical Observatory established by Gunma prefecture, Japan, at the Florence and George Wise Observatory, operated by the Tel-Aviv University, Israel and at Piszkésteto, the mountain station of Konkoly Observatory of the Hungarian Academy of Science, Hungary. This publication makes use of data products from the Two Micron All Sky Survey, a joint project of the University of Massachusetts and the Infrared Processing and Analysis Center / California Institute of Technology, funded by the National Aeronautics and Space Administration and the National Science Foundation. The Digitized Sky Survey was produced at the Space Telescope Science Institute under US Government grant NAG W-2166. The images of these surveys are based on photographic data obtained using the Oschin Schmidt Telescope on Palomar Mountain and the UK

SUPERNOVA LIGHT CURVES POWERED BY FALLBACK ACCRETION

Energy Technology Data Exchange (ETDEWEB)

Dexter, Jason; Kasen, Daniel, E-mail: jdexter@berkeley.edu [Departments of Physics and Astronomy, University of California, Berkeley, CA 94720 (United States)

2013-07-20

Some fraction of the material ejected in a core collapse supernova explosion may remain bound to the compact remnant, and eventually turn around and fall back. We show that the late time ({approx}>days) power potentially associated with the accretion of this 'fallback' material could significantly affect the optical light curve, in some cases producing super-luminous or otherwise peculiar supernovae. We use spherically symmetric hydrodynamical models to estimate the accretion rate at late times for a range of progenitor masses and radii and explosion energies. The accretion rate onto the proto-neutron star or black hole decreases as M-dot {proportional_to}t{sup -5/3} at late times, but its normalization can be significantly enhanced at low explosion energies, in very massive stars, or if a strong reverse shock wave forms at the helium/hydrogen interface in the progenitor. If the resulting super-Eddington accretion drives an outflow which thermalizes in the outgoing ejecta, the supernova debris will be re-energized at a time when photons can diffuse out efficiently. The resulting light curves are different and more diverse than previous fallback supernova models which ignored the input of accretion power and produced short-lived, dim transients. The possible outcomes when fallback accretion power is significant include super-luminous ({approx}> 10{sup 44} erg s{sup -1}) Type II events of both short and long durations, as well as luminous Type I events from compact stars that may have experienced significant mass loss. Accretion power may unbind the remaining infalling material, causing a sudden decrease in the brightness of some long duration Type II events. This scenario may be relevant for explaining some of the recently discovered classes of peculiar and rare supernovae.

A Data-driven Study of RR Lyrae Near-IR Light Curves: Principal Component Analysis, Robust Fits, and Metallicity Estimates

Science.gov (United States)

Hajdu, Gergely; Dékány, István; Catelan, Márcio; Grebel, Eva K.; Jurcsik, Johanna

2018-04-01

RR Lyrae variables are widely used tracers of Galactic halo structure and kinematics, but they can also serve to constrain the distribution of the old stellar population in the Galactic bulge. With the aim of improving their near-infrared photometric characterization, we investigate their near-infrared light curves, as well as the empirical relationships between their light curve and metallicities using machine learning methods. We introduce a new, robust method for the estimation of the light-curve shapes, hence the average magnitudes of RR Lyrae variables in the K S band, by utilizing the first few principal components (PCs) as basis vectors, obtained from the PC analysis of a training set of light curves. Furthermore, we use the amplitudes of these PCs to predict the light-curve shape of each star in the J-band, allowing us to precisely determine their average magnitudes (hence colors), even in cases where only one J measurement is available. Finally, we demonstrate that the K S-band light-curve parameters of RR Lyrae variables, together with the period, allow the estimation of the metallicity of individual stars with an accuracy of ∼0.2–0.25 dex, providing valuable chemical information about old stellar populations bearing RR Lyrae variables. The methods presented here can be straightforwardly adopted for other classes of variable stars, bands, or for the estimation of other physical quantities.

Effects Total Solar Eclipse to Nasty Behaviour of the Several Legume Plants as a Result Student Research

Science.gov (United States)

Anggraeni, S.; Diana, S.; Supriatno, B.

2017-09-01

Some group students of plant Physiology course have given task to do free inquiry. They investigated of the nasty behaviour of several legume plants in response to changes in light during the partial solar eclipse that occurred at March 9, 2016. The investigation carried out in UPI Bandung, West Java, Indonesia, which is in the penumbra region of a total solar eclipse with the location coordinates of latitude: -6.86105, longitude: 07.59071, S 6057’ 37.53553 “and E 107035’ 24.29141”. They were measuring the movement of opening leaves every ten minutes at the beginning of the start until the end of the eclipse compared with the behaviour without eclipsing. Influence is expressed by comparing the leaf opening movement (measured in the form of leaf angular) at the time of the eclipse with a normal day. Each group was observed for one plant of the legume, there are: Mimosa pudica, Bauhinia purpurea, Caesalpinia pulcherrima, and Arachis pintoi. The results showed that the changes in leaf angular in plants Mimosa pudica, Caesalpinia pulcherrima, and Arachis pintoi differently significant, except for Bauhinia purpurea. In conclusion, the total solar eclipse in the penumbra area affects the movement of some nasty legume plants. It is recommended to conduct a study of the nasty behaviour of legume plants in the area umbra in the path of a total solar eclipse.

Solar Eclipse Computer API: Planning Ahead for August 2017

Science.gov (United States)

Bartlett, Jennifer L.; Chizek Frouard, Malynda; Lesniak, Michael V.; Bell, Steve

2016-01-01

With the total solar eclipse of 2017 August 21 over the continental United States approaching, the U.S. Naval Observatory (USNO) on-line Solar Eclipse Computer can now be accessed via an application programming interface (API). This flexible interface returns local circumstances for any solar eclipse in JavaScript Object Notation (JSON) that can be incorporated into third-party Web sites or applications. For a given year, it can also return a list of solar eclipses that can be used to build a more specific request for local circumstances. Over the course of a particular eclipse as viewed from a specific site, several events may be visible: the beginning and ending of the eclipse (first and fourth contacts), the beginning and ending of totality (second and third contacts), the moment of maximum eclipse, sunrise, or sunset. For each of these events, the USNO Solar Eclipse Computer reports the time, Sun's altitude and azimuth, and the event's position and vertex angles. The computer also reports the duration of the total phase, the duration of the eclipse, the magnitude of the eclipse, and the percent of the Sun obscured for a particular eclipse site. On-line documentation for using the API-enabled Solar Eclipse Computer, including sample calls, is available (http://aa.usno.navy.mil/data/docs/api.php). The same Web page also describes how to reach the Complete Sun and Moon Data for One Day, Phases of the Moon, Day and Night Across the Earth, and Apparent Disk of a Solar System Object services using API calls.For those who prefer using a traditional data input form, local circumstances can still be requested that way at http://aa.usno.navy.mil/data/docs/SolarEclipses.php. In addition, the 2017 August 21 Solar Eclipse Resource page (http://aa.usno.navy.mil/data/docs/Eclipse2017.php) consolidates all of the USNO resources for this event, including a Google Map view of the eclipse track designed by Her Majesty's Nautical Almanac Office (HMNAO). Looking further ahead, a

Supernova light-curve fitters and dark energy

Energy Technology Data Exchange (ETDEWEB)

Bengochea, Gabriel R., E-mail: gabriel@iafe.uba.a [Instituto de Astronomia y Fisica del Espacio (IAFE), CC 67, Suc. 28, 1428 Buenos Aires (Argentina)

2011-01-24

We show that when a procedure is made to remove the tension between a supernova Ia (SN Ia) data set and observations from BAO and CMB, there might be the case where the same SN Ia set built with two different light-curve fitters behaves as two separate and distinct supernova sets, and the tension found by some authors between supernova sets actually could be due to tension or inconsistency between fitters. We also show that the information of the fitter used in an SN Ia data set could be relevant to determine whether phantom type models are favored or not when such a set is combined with the BAO/CMB joint parameter.

Supernova light-curve fitters and dark energy

International Nuclear Information System (INIS)

Bengochea, Gabriel R.

2011-01-01

We show that when a procedure is made to remove the tension between a supernova Ia (SN Ia) data set and observations from BAO and CMB, there might be the case where the same SN Ia set built with two different light-curve fitters behaves as two separate and distinct supernova sets, and the tension found by some authors between supernova sets actually could be due to tension or inconsistency between fitters. We also show that the information of the fitter used in an SN Ia data set could be relevant to determine whether phantom type models are favored or not when such a set is combined with the BAO/CMB joint parameter.

Mastering Eclipse plug-in development

CERN Document Server

Blewitt, Alex

2014-01-01

If you are a Java developer who is familiar with the Eclipse plug-in environment, this book covers the advanced concepts that you need to know to achieve true expertise. Prior experience in creating Eclipse plug-ins is assumed for this book.

Changes in environmental radon related with the day eclipse

International Nuclear Information System (INIS)

Gaso P, M.I.; Cervantes, M.L.; Segovia A, N.; Espindola, V.H.

1992-05-01

Systematic studies of radon and of gamma dose in air in the Nuclear Center of Mexico during a period of nine months that include the total Sun eclipse happened at July 11, 1991 were carried out. The radon concentrations were measured with an electronic equipment that measures in continuous form and the rate of gamma dose in air was obtained with a ionization chamber. The results show that the radon fluctuations in air are influenced by the meteorological changes showing behaviors different to long and short term. The variations of long term are correlated directly with the external temperature while those of short term have an inverse relationship with the temperature. These last results are discussed regarding drastic atmospheric changes happened in the period and those light changes result of the total Sun eclipse. The rate of gamma dose in air showed stability during the study. (Author)

Type II Supernova Light Curves and Spectra from the CfA

Science.gov (United States)

Hicken, Malcolm; Friedman, Andrew S.; Blondin, Stephane; Challis, Peter; Berlind, Perry; Calkins, Mike; Esquerdo, Gil; Matheson, Thomas; Modjaz, Maryam; Rest, Armin; Kirshner, Robert P.

2017-11-01

We present multiband photometry of 60 spectroscopically confirmed supernovae (SNe): 39 SNe II/IIP, 19 IIn, 1 IIb, and 1 that was originally classified as a IIn but later as a Ibn. Of these, 46 have only optical photometry, 6 have only near-infrared (NIR) photometry, and 8 have both optical and NIR. The median redshift of the sample is 0.016. We also present 195 optical spectra for 48 of the 60 SN. There are 26 optical and 2 NIR light curves of SNe II/IIP with redshifts z> 0.01, some of which may give rise to useful distances for cosmological applications. All photometry was obtained between 2000 and 2011 at the Fred Lawrence Whipple Observatory (FLWO), via the 1.2 m and 1.3 m PAIRITEL telescopes for the optical and NIR, respectively. Each SN was observed in a subset of the u\\prime {UBVRIr}\\prime I\\prime {{JHK}}s bands. There are a total of 2932 optical and 816 NIR light curve points. Optical spectra were obtained using the FLWO 1.5 m Tillinghast telescope with the FAST spectrograph and the MMT Telescope with the Blue Channel Spectrograph. Our photometry is in reasonable agreement with select samples from the literature: two-thirds of our star sequences have average V offsets within ±0.02 mag and roughly three-quarters of our light curves have average differences within ±0.04 mag. The data from this work and the literature will provide insight into SN II explosions, help with developing methods for photometric SN classification, and contribute to their use as cosmological distance indicators.

Absolute Distances to Nearby Type Ia Supernovae via Light Curve Fitting Methods

Science.gov (United States)

Vinkó, J.; Ordasi, A.; Szalai, T.; Sárneczky, K.; Bányai, E.; Bíró, I. B.; Borkovits, T.; Hegedüs, T.; Hodosán, G.; Kelemen, J.; Klagyivik, P.; Kriskovics, L.; Kun, E.; Marion, G. H.; Marschalkó, G.; Molnár, L.; Nagy, A. P.; Pál, A.; Silverman, J. M.; Szakáts, R.; Szegedi-Elek, E.; Székely, P.; Szing, A.; Vida, K.; Wheeler, J. C.

2018-06-01

We present a comparative study of absolute distances to a sample of very nearby, bright Type Ia supernovae (SNe) derived from high cadence, high signal-to-noise, multi-band photometric data. Our sample consists of four SNe: 2012cg, 2012ht, 2013dy and 2014J. We present new homogeneous, high-cadence photometric data in Johnson–Cousins BVRI and Sloan g‧r‧i‧z‧ bands taken from two sites (Piszkesteto and Baja, Hungary), and the light curves are analyzed with publicly available light curve fitters (MLCS2k2, SNooPy2 and SALT2.4). When comparing the best-fit parameters provided by the different codes, it is found that the distance moduli of moderately reddened SNe Ia agree within ≲0.2 mag, and the agreement is even better (≲0.1 mag) for the highest signal-to-noise BVRI data. For the highly reddened SN 2014J the dispersion of the inferred distance moduli is slightly higher. These SN-based distances are in good agreement with the Cepheid distances to their host galaxies. We conclude that the current state-of-the-art light curve fitters for Type Ia SNe can provide consistent absolute distance moduli having less than ∼0.1–0.2 mag uncertainty for nearby SNe. Still, there is room for future improvements to reach the desired ∼0.05 mag accuracy in the absolute distance modulus.

Changes in environmental radon related with the day eclipse; Cambios de radon ambiental relacionados con el eclipse del dia 11 de julio 1991

Energy Technology Data Exchange (ETDEWEB)

Gaso P, M I; Cervantes, M L; Segovia A, N; Espindola, V H

1992-05-15

Systematic studies of radon and of gamma dose in air in the Nuclear Center of Mexico during a period of nine months that include the total Sun eclipse happened at July 11, 1991 were carried out. The radon concentrations were measured with an electronic equipment that measures in continuous form and the rate of gamma dose in air was obtained with a ionization chamber. The results show that the radon fluctuations in air are influenced by the meteorological changes showing behaviors different to long and short term. The variations of long term are correlated directly with the external temperature while those of short term have an inverse relationship with the temperature. These last results are discussed regarding drastic atmospheric changes happened in the period and those light changes result of the total Sun eclipse. The rate of gamma dose in air showed stability during the study. (Author)

Boise State's Idaho Eclipse Outreach Program

Science.gov (United States)

Davis, Karan; Jackson, Brian

2017-10-01

The 2017 total solar eclipse is an unprecedented opportunity for astronomical education throughout the continental United States. With the path of totality passing through 14 states, from Oregon to South Carolina, the United States is expecting visitors from all around the world. Due to the likelihood of clear skies, Idaho was a popular destination for eclipse-chasers. In spite of considerable enthusiasm and interest by the general population, the resources for STEM outreach in the rural Pacific Northwest are very limited. In order to help prepare Idaho for the eclipse, we put together a crowdfunding campaign through the university and raised over $10,000. Donors received eclipse shades as well as information about the eclipse specific to Idaho. Idaho expects 500,000 visitors, which could present a problem for the many small, rural towns scattered across the path of totality. In order to help prepare and equip the public for the solar eclipse, we conducted a series of site visits to towns in and near the path of totality throughout Idaho. To maximize the impact of this effort, the program included several partnerships with local educational and community organizations and a focus on the sizable refugee and low-income populations in Idaho, with considerable attendance at most events.

Eclipse of epsilon Aurigae

Science.gov (United States)

Templeton, Matthew R.

2009-07-01

The bright, long-period, eclipsing binary star epsilon Aurigae is predicted to begin its next eclipse late July or early August of 2009. Epsilon Aurigae is now past solar conjunction and has reappeared as a morning object. All observers -- both visual and instrumental -- are encouraged to contribute observations of the eclipse during the next two years, beginning immediately for morning observers. Observations are urgently requested right now because it is less likely to be observed in the morning, and the eclipse will begin within the next month. The AAVSO is participating in a global campaign to record this eclipse as part of the International Year of Astronomy 2009 celebrations, organized by the Citizen Sky project (http://www.citizensky.org). For experienced visual observers, please observe this star on a weekly basis, using charts available via VSP from the AAVSO website. For novice visual observers, we recommend participating in this observing program by following the Citizen Sky 10-Star tutorial program, which provides a simple training experience in variable star observing. Photoelectric observers belonging to the AAVSO PEP-V program may submit data as usual via the WebObs feature of the AAVSO website Blue&Gold section. Photoelectric observers may also contribute reduced observations in all filters (including infrared J- and H-bands) directly to the AAVSO via WebObs. Observers using wide-field CCD and DSLR systems are also encouraged to participate; avoid saturating the star. For those with narrower-field systems (D Jeffrey Hopkins are co-leading the precision photometry efforts.

Evaluating the Eclipse: How good was it?

Science.gov (United States)

Noel-Storr, Jacob; InsightSTEM Evaluation Team

2018-01-01

We present findings from the evaluation program carried out of education, public outreach, and communication activities around the "Great American Eclipse" of August 21, 2017. We include findings drawn from the experiences of 30 participants in planning activities prior to the eclipse and 31 recipients of mini-grants for eclipse activities supported by the American Astronomical Society through a grant from the National Science Foundation. We synthesize evaluations gathered by these and other volunteering organizations to provide a multi-site picture of experiences and learning outcomes at eclipse-related events - both in the path of totality and in partial eclipse settings. We make use of qualitative and quantitative responses representing over 30,000 individuals who observed (or tried to observe) the eclipse. We will share findings from across the range of programs included in our evaluation network along with specific highlights. We emphasize a reflection on the motivation and activity behind the 2017 eclipse, and how to leverage the lessons learned for future events on this scale (such as the eclipse of April 8, 2024) along with messages relevant to other events connected with astronomical phenomena, or in multi-site settings.This work was supported in part by the National Science Foundation under Grant No. 1564535 awarded to the American Astronomical Society. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author and do not necessarily reflect the views of the National Science Foundation or the American Astronomical Society.

Is an eclipse described in the Odyssey?

Science.gov (United States)

Baikouzis, Constantino; Magnasco, Marcelo O

2008-07-01

Plutarch and Heraclitus believed a certain passage in the 20th book of the Odyssey ("Theoclymenus's prophecy") to be a poetic description of a total solar eclipse. In the late 1920s, Schoch and Neugebauer computed that the solar eclipse of 16 April 1178 B.C.E. was total over the Ionian Islands and was the only suitable eclipse in more than a century to agree with classical estimates of the decade-earlier sack of Troy around 1192-1184 B.C.E. However, much skepticism remains about whether the verses refer to this, or any, eclipse. To contribute to the issue independently of the disputed eclipse reference, we analyze other astronomical references in the Epic, without assuming the existence of an eclipse, and search for dates matching the astronomical phenomena we believe they describe. We use three overt astronomical references in the epic: to Boötes and the Pleiades, Venus, and the New Moon; we supplement them with a conjectural identification of Hermes's trip to Ogygia as relating to the motion of planet Mercury. Performing an exhaustive search of all possible dates in the span 1250-1115 B.C., we looked to match these phenomena in the order and manner that the text describes. In that period, a single date closely matches our references: 16 April 1178 B.C.E. We speculate that these references, plus the disputed eclipse reference, may refer to that specific eclipse.

Statistical analysis of the W Cyg light curve

International Nuclear Information System (INIS)

Klyus, I.A.

1983-01-01

A statistical analysis of the light curve of W Cygni has been carried out. The process of brightness variations brightness of the star is shown to be a stationary stochastic one. The hypothesis of stationarity of the process was checked at the significance level of α=0.05. Oscillations of the brightness with average durations of 131 and 250 days have been found. It is proved that oscillations are narrow-band noise, i.e. cycles. Peaks on the power spectrum corresponding to these cycles exceed 99% confidence interval. It has been stated that the oscillations are independent

The Great American Eclipse: Lessons Learned from Public Education

Science.gov (United States)

Edson, Shauna Elizabeth; Phoebe Waterman Haas Public Observatory

2018-01-01

The total solar eclipse of 2017 was a high-profile opportunity for nationwide public education. Astronomy experts suddenly became vital sources of information for a lay population whose interest in the eclipse greatly surpassed expectations. At the National Air and Space Museum, we leveraged our relatively accessible location and particularly diverse audience to help thousands of people, from novices to enthusiasts, prepare to view the eclipse safely. The goal was to empower all people so they could experience this unique astronomical event, understand what was happening, and observe the Sun safely. Over the course of two years spent talking with the public about the eclipse, we encountered common misconceptions, worries about safety or liability, and people experiencing confusion or information overload. We developed guidelines for handling these challenges, from correcting misinformation to managing the sudden spike in demand for glasses just before August 21.In particular, we helped people understand the following essential points:- The total phase of the eclipse is only visible from a limited path.- The partial eclipse is visible from a large area outside the path of totality.- The eclipse takes up to three hours from start to finish, providing ample time for viewing.- The Sun can be observed safely using several methods, including but not limited to eclipse glasses.- The eclipse happens because the Moon’s orbit is taking it directly between the Sun and the Earth.- Eclipses do not happen every month because the Moon’s orbit is tilted with respect to the Earth's orbital plane.- Students in schools can safely view the eclipse, with proper protection and supervision, to prevent eye damage and minimize liability.Public education about the eclipse appears to have been successful, as evidenced by the large number of people who saw their first total solar eclipse and the absence of reported eye damage cases. Amidst the excitement, photographs, and stories that

Resource Letter OSE-1: Observing Solar Eclipses

Science.gov (United States)

Pasachoff, Jay M.; Fraknoi, Andrew

2017-07-01

This Resource Letter provides a guide to the available literature, listing selected books, articles, and online resources about scientific, cultural, and practical issues related to observing solar eclipses. It is timely, given that a total solar eclipse will cross the continental United States on August 21, 2017. The next total solar eclipse path crossing the U.S. and Canada will be on April 8, 2024. In 2023, the path of annularity of an annular eclipse will cross Mexico, the United States, and Canada, with partial phases visible throughout those countries.

γ DORADUS PULSATIONS IN THE ECLIPSING BINARY STAR KIC 6048106

Energy Technology Data Exchange (ETDEWEB)

Lee, Jae Woo, E-mail: jwlee@kasi.re.kr [Korea Astronomy and Space Science Institute, Daejeon 34113 (Korea, Republic of)

2016-12-20

We present the Kepler photometry of KIC 6048106, which is exhibiting the O’Connell effect and multiperiodic pulsations. Including a starspot on either of the components, light-curve synthesis indicates that this system is a semi-detached Algol with a mass ratio of 0.211, an orbital inclination of 73.°9, and a large temperature difference of 2534 K. To examine in detail both the spot variations and pulsations, we separately analyzed the Kepler time-series data at the interval of an orbital period in an iterative way. The results reveal that the variable asymmetries of the light maxima can be interpreted as the changes with time of a magnetic cool spot on the secondary component. Multiple frequency analyses were performed in the outside-eclipse light residuals after removal of the binarity effects from the observed Kepler data. We detected 30 frequencies with signal to noise amplitude ratios larger than 4.0, of which six ( f {sub 2}– f {sub 6} and f {sub 10}) can be identified as high-order (17 ≤  n  ≤ 25) low-degree ( ℓ  = 2) gravity-mode pulsations that were stable during the observing run of 200 days. In contrast, the other frequencies may be harmonic and combination terms. For the six frequencies, the pulsation periods and pulsation constants are in the ranges of 0.352–0.506 days and 0.232–0.333 days, respectively. These values and the position on the Hertzsprung–Russell diagram demonstrate that the primary star is a γ Dor variable. The evolutionary status and the pulsation nature of KIC 6048106 are discussed.

DETERMINISTIC COMPONENTS IN THE LIGHT CURVE AMPLITUDE OF Y OPH

International Nuclear Information System (INIS)

Pop, Alexandru; Turcu, Vlad; Vamos, Calin

2010-01-01

About two decades after the discovery of the amplitude decline of the light curve of the classical Cepheid Y Oph, its study is resumed using an increased amount of homogenized data and an extended time base. In our approach, the investigation of different time series concerning the light curve amplitude of Y Oph is not only the reason for the present study, but also a stimulus for developing a coherent methodology for studying long- and short-term variability phenomena in variable stars, taking into account the details of concrete observing conditions: amount of data, data sampling, time base, and individual errors of observational data. The statistical significance of this decreasing trend was estimated by assuming its linearity. We approached the decision-making process by formulating adequate null and alternative hypotheses, and testing the value of the regression line slope for different data sets via Monte Carlo simulations. A variability analysis, through various methods, of the original data and of the residuals obtained after removing the linear trend was performed. We also proposed a new statistical test, based on amplitude spectrum analysis and Monte Carlo simulations, intended to evaluate how detectible is a given (linear) trend in well-defined observing conditions: the trend detection probability. The main conclusion of our study on Y Oph is that, even if the false alarm probability is low enough to consider the decreasing trend to be statistically significant, the available data do not allow us to obtain a reasonably powerful test. We are able to confirm the light curve amplitude decline, and the order of magnitude of its slope with a better statistical substantiation. According to the obtained values of the trend detection probability, it seems that the trend we are dealing with is marked by a low detectibility. Our attempt to find signs of possible variability phenomena at shorter timescales ended by emphasizing the relative constancy of our data

Notable Images of the 2017 Total Solar Eclipse

Science.gov (United States)

Wilson, Teresa; Dahiwale, Aishwarya; Nemiroff, Robert; Bonnell, Jerry

2018-01-01

The "Great American Eclipse" – the total solar eclipse visible across the USA on 21 August 2017 – resulted in some notable eclipse images and videos high in educational and scientific value. Some of the images that were selected to appear on the Astronomy Picture of the Day (APOD) website are shown in high resolution accompanied by educational descriptions. The questions of whether this eclipse was the most viewed and the most photographed event of any type in human history will be discussed. People are invited to come by and share their own eclipse images and stories.

Accurate Masses, Radii, and Temperatures for the Eclipsing Binary V2154 Cyg, and Tests of Stellar Evolution Models

Science.gov (United States)

Bright, Jane; Torres, Guillermo

2018-01-01

We report new spectroscopic observations of the F-type triple system V2154 Cyg, in which two of the stars form an eclipsing binary with a period of 2.6306303 ± 0.0000038 days. We combine the results from our spectroscopic analysis with published light curves in the uvby Strömgren passbands to derive the first reported absolute dimensions of the stars in the eclipsing binary. The masses and radii are measured with high accuracy to better than 1.5% precision. For the primary and secondary respectively, we find that the masses are 1.269 ± 0.017 M⊙ and 0.7542 ± 0.0059 M⊙, the radii are 1.477 ± 0.012 R⊙ and 0.7232 ± 0.0091R⊙, and the temperatures are 6770 ± 150 K and 5020 ± 150 K. Current models of stellar evolution agree with the measured properties of the primary, but the secondary is larger than predicted. This may be due to activity in the secondary, as has been shown for other systems with a star of similar mass with this same discrepancy.The SAO REU program is funded by the National Science Foundation REU and Department of Defense ASSURE programs under NSF Grant AST-1659473, and by the Smithsonian Institution. GT acknowledges partial support for this work from NSF grant AST-1509375.

The (Almost) Unseen Total Eclipse of 1831

Science.gov (United States)

Bartky, Ian R.

2008-03-01

The total eclipse of August 1831 began at sunrise in Australia, swept across the western South Pacific Ocean, and ended at sunset in the central South Pacific. As a result of the eclipse's path over mostly uninhabited ocean, the region's sparse European (British) population, and near-useless local predictions of the event at Hobart and Sydney in almanacs sold to the general public, almost no one witnessed its passage. In an attempt to document the eclipse, journals of naive observers - those having no access to a prediction - were examined. Thus far, the sole record is in the Pitcairn Island Register Book. Considering the Pitcairners' extreme isolation and the rather modest partial eclipse that occurred there, the entry is a surprising one; however, it can be explained in terms of events associated with their initial removal to Tahiti in March 1831 followed by their return home in June. Further, an authoritative means to identify any issues associated with eclipse predictions compiled for private-sector almanacs came in 1833 when sweeping changes in the British Nautical Almanac's section on eclipses were instituted.

A Statistical Characterization of Reflection and Refraction in the Atmospheres of sub-Saturn Kepler Planet Candidates

Science.gov (United States)

Sheets, Holly A.; Deming, Drake; Arney, Giada; Meadows, Victoria

2016-01-01

We present the results of our method to detect small atmospheric signals in Kepler's close-in, sub-Saturn planet candidate light curves. We detect an average secondary eclipse for groups of super-Earth, Neptune-like, and other sub-Saturn-sized candidates by scaling and combining photometric data of the groups of candidates such that the eclipses add constructively. This greatly increases the signal-to-noise compared to combining eclipses for individual planets. We have modified our method for averaging short cadence light curves of multiple planet candidates (2014, ApJ, 794, 133), and have applied it to long cadence data, accounting for the broadening of the eclipse due to the 30 minute cadence. We then use the secondary eclipse depth to determine the average albedo for the group. In the short cadence data, we found that a group of close-in sub-Saturn candidates (1 to 6 Earth radii) was more reflective (geometric A ~ 0.22) than typical hot Jupiters (geometric A ~ 0.06 to 0.11: Demory 2014, ApJL, 789, L20). With the larger number of candidates available in long cadence, we improve the resolution in radius and consider groups of candidates with radii between 1 and 2, 2 and 4, and 4 and 6 Earth radii. We also modify our averaging technique to search for refracted light just before and after transit in the Kepler candidate light curves, as modelled by Misra and Meadows (2014, ApJL, 795, L14).

Getting started with Eclipse Juno

CERN Document Server

Durelli, Vinicius H S; Teixeira, Rafael Medeiros

2013-01-01

Written as a concise yet practical guide that details the main features which are usually required by a programmer who makes use of the Eclipse platform, this book covers Eclipse 3.8 in a way that is accessible to the Java novice and expert alike. The reader is guided through a series of hands-on examples that introduce Eclipse and some of its plugins.The primary audience for this book are the Java programmers. This book has been written in a way that it is accessible both to beginners and advanced Java programmers alike. Also, if you are a seasoned Java developer who has been using another ID

Bringing the Great American Solar Eclipse to West Virginia

Science.gov (United States)

Keesee, A. M.; Williamson, K.; Robertson-Honecker, J.

2017-12-01

West Virginia experienced up to 90% coverage during the Great American Solar Eclipse on August 21st. To reach the greatest number of West Virginians, we targeted educators and the 4-H program to provide those community leaders with the tools to help students learn about and safely view the eclipse. We developed a website that consolodated relevant eclipse activities, fact sheets, and outreach videos to train educators and others in the public about the science of the eclipse and how to view a partial eclipse safely. The 4-H Summer Experiement used at all 4-H summer camps and events was designed to focus on the eclipse. We distributed over 20,000 custom designed eclipse glasses. These were distributed to teachers through an online request system and to 4-H members involved in summer activities. We hosted a pre-eclipse event on the campus of West Virginia University for the public to learn about the science of the eclipse, relevant research being conducted at the university, and provide tips for safe viewing. Student volunteers were available on campus during the day of the eclipse to hand out glasses and answer questions. We will present the results of our outreach and events as well as lessons learned for the 2024 eclipse. Support for this project was provided by the WVU Department of Physics and Astronomy, WVU Extension, the WV Space Grant Consortium, a WVU internal grant, the Green Bank Observatory, and individual supporters of a crowdfunding campaign.

SiFTO: An Empirical Method for Fitting SN Ia Light Curves

Science.gov (United States)

Conley, A.; Sullivan, M.; Hsiao, E. Y.; Guy, J.; Astier, P.; Balam, D.; Balland, C.; Basa, S.; Carlberg, R. G.; Fouchez, D.; Hardin, D.; Howell, D. A.; Hook, I. M.; Pain, R.; Perrett, K.; Pritchet, C. J.; Regnault, N.

2008-07-01

We present SiFTO, a new empirical method for modeling Type Ia supernova (SN Ia) light curves by manipulating a spectral template. We make use of high-redshift SN data when training the model, allowing us to extend it bluer than rest-frame U. This increases the utility of our high-redshift SN observations by allowing us to use more of the available data. We find that when the shape of the light curve is described using a stretch prescription, applying the same stretch at all wavelengths is not an adequate description. SiFTO therefore uses a generalization of stretch which applies different stretch factors as a function of both the wavelength of the observed filter and the stretch in the rest-frame B band. We compare SiFTO to other published light-curve models by applying them to the same set of SN photometry, and demonstrate that SiFTO and SALT2 perform better than the alternatives when judged by the scatter around the best-fit luminosity distance relationship. We further demonstrate that when SiFTO and SALT2 are trained on the same data set the cosmological results agree. Based on observations obtained with MegaPrime/MegaCam, a joint project of CFHT and CEA/DAPNIA, at the Canada-France-Hawaii Telescope (CFHT) which is operated by the National Research Council (NRC) of Canada, the Institut National des Sciences de l'Univers of the Centre National de la Recherche Scientifique (CNRS) of France, and the University of Hawaii. This work is based in part on data products produced at the Canadian Astronomy Data Centre as part of the Canada-France-Hawaii Telescope Legacy Survey, a collaborative project of NRC and CNRS.

ASTEROID LIGHT CURVES FROM THE PALOMAR TRANSIENT FACTORY SURVEY: ROTATION PERIODS AND PHASE FUNCTIONS FROM SPARSE PHOTOMETRY

Energy Technology Data Exchange (ETDEWEB)

Waszczak, Adam [Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA 91125 (United States); Chang, Chan-Kao; Cheng, Yu-Chi; Ip, Wing-Huen; Kinoshita, Daisuke [Institute of Astronomy, National Central University, Jhongli, Taiwan (China); Ofek, Eran O. [Benoziyo Center for Astrophysics, Weizmann Institute of Science, Rehovot (Israel); Laher, Russ; Surace, Jason [Spitzer Science Center, California Institute of Technology, Pasadena, CA 91125 (United States); Masci, Frank; Helou, George [Infrared Processing and Analysis Center, California Institute of Technology, Pasadena, CA 91125 (United States); Levitan, David; Prince, Thomas A.; Kulkarni, Shrinivas, E-mail: waszczak@caltech.edu [Division of Physics, Mathematics and Astronomy, California Institute of Technology, Pasadena, CA 91125 (United States)

2015-09-15

We fit 54,296 sparsely sampled asteroid light curves in the Palomar Transient Factory survey to a combined rotation plus phase-function model. Each light curve consists of 20 or more observations acquired in a single opposition. Using 805 asteroids in our sample that have reference periods in the literature, we find that the reliability of our fitted periods is a complicated function of the period, amplitude, apparent magnitude, and other light-curve attributes. Using the 805-asteroid ground-truth sample, we train an automated classifier to estimate (along with manual inspection) the validity of the remaining ∼53,000 fitted periods. By this method we find that 9033 of our light curves (of ∼8300 unique asteroids) have “reliable” periods. Subsequent consideration of asteroids with multiple light-curve fits indicates a 4% contamination in these “reliable” periods. For 3902 light curves with sufficient phase-angle coverage and either a reliable fit period or low amplitude, we examine the distribution of several phase-function parameters, none of which are bimodal though all correlate with the bond albedo and with visible-band colors. Comparing the theoretical maximal spin rate of a fluid body with our amplitude versus spin-rate distribution suggests that, if held together only by self-gravity, most asteroids are in general less dense than ∼2 g cm{sup −3}, while C types have a lower limit of between 1 and 2 g cm{sup −3}. These results are in agreement with previous density estimates. For 5–20 km diameters, S types rotate faster and have lower amplitudes than C types. If both populations share the same angular momentum, this may indicate the two types’ differing ability to deform under rotational stress. Lastly, we compare our absolute magnitudes (and apparent-magnitude residuals) to those of the Minor Planet Center’s nominal (G = 0.15, rotation-neglecting) model; our phase-function plus Fourier-series fitting reduces asteroid photometric rms

Common Envelope Light Curves. I. Grid-code Module Calibration

Energy Technology Data Exchange (ETDEWEB)

Galaviz, Pablo; Marco, Orsola De; Staff, Jan E.; Iaconi, Roberto [Department of Physics and Astronomy, Macquarie University, Sydney, NSW (Australia); Passy, Jean-Claude, E-mail: Pablo.Galaviz@me.com [Argelander-Institut für Astronomie, Auf dem Hügel 71, D-53121 Bonn (Germany)

2017-04-01

The common envelope (CE) binary interaction occurs when a star transfers mass onto a companion that cannot fully accrete it. The interaction can lead to a merger of the two objects or to a close binary. The CE interaction is the gateway of all evolved compact binaries, all stellar mergers, and likely many of the stellar transients witnessed to date. CE simulations are needed to understand this interaction and to interpret stars and binaries thought to be the byproduct of this stage. At this time, simulations are unable to reproduce the few observational data available and several ideas have been put forward to address their shortcomings. The need for more definitive simulation validation is pressing and is already being fulfilled by observations from time-domain surveys. In this article, we present an initial method and its implementation for post-processing grid-based CE simulations to produce the light curve so as to compare simulations with upcoming observations. Here we implemented a zeroth order method to calculate the light emitted from CE hydrodynamic simulations carried out with the 3D hydrodynamic code Enzo used in unigrid mode. The code implements an approach for the computation of luminosity in both optically thick and optically thin regimes and is tested using the first 135 days of the CE simulation of Passy et al., where a 0.8  M {sub ⊙} red giant branch star interacts with a 0.6  M {sub ⊙} companion. This code is used to highlight two large obstacles that need to be overcome before realistic light curves can be calculated. We explain the nature of these problems and the attempted solutions and approximations in full detail to enable the next step to be identified and implemented. We also discuss our simulation in relation to recent data of transients identified as CE interactions.

Living matter: the "lunar eclipse" phenomena.

Science.gov (United States)

Korpan, Nikolai N

2010-01-01

The present investigations describe a unique phenomenon, namely the phenomenon of the "lunar eclipse", which has been observed and discovered by the author in living substance during the freeze-thawing processes in vivo using temperatures of various intensities and its cryosurgical response in animal experiment. Similar phenomena author has observed in nature, namely the total lunar eclipse and total solar eclipse. In this experimental study 76 animals (mongrel dogs) were investigated. A disc cryogenic probe was placed on the pancreas after the laparotomy. For cryosurgical exposure a temperature range of -40 degrees C, -80 degrees C, -120 degrees C and -180 degrees C was selected in contact with pancreas parenchyma. The freeze-thaw cycle was monitored by intraoperative ultrasound before, during and after cryosurgery. Each cryolesion was observed for one hour after thawing intraoperatively. Immediately after freezing, during the thawing process, the snow-white pancreas parenchyma, frozen hard to an ice block and resembling a full moon with a sharp demarcation line, gradually assumed a ruby-red shade and a hemispherical shape as it grew in size depend on reconstruction vascular circulation from the periphery to the center. This snow-white cryogenic lesion dissolved in the same manner in all animal tissues. The "lunar eclipse" phenomenon contributes to a fundamental understanding of the mechanisms of biological tissue damage during low temperature exposure in cryoscience and cryomedicine. Properties of the pancreas parenchyma response during the phenomenon of the "lunar eclipse" provide important insights into the mechanisms of damage and the formation of cryogenic lesion immediately after thawing in cryosurgery. Vascular changes and circulatory stagnation are commonly considered to be the main mechanism of biological tissue injury during low temperature exposure. The phenomenon of the "lunar eclipse" suggests that cryosurgery is the first surgical technique to use

Strategies for the public communication of eclipses

Science.gov (United States)

Bretones, P. S.

2015-03-01

Eclipses are among the celestial events that draw the attention of the public. This paper discusses strategies for using eclipses as public communication opportunities in the media. It discusses the impact of articles written by the author and analysis of published material for 25 observed eclipses over the last 30 years by mass media in the state of São Paulo, Brazil. On each occasion, a standard article was posted on the Internet and sent to newspapers, radio and TV with information, such as: date, time and local circumstances; type of the eclipse; area of visibility; explanation; diagram of the phenomenon, and the Moon's path through Earth's shadow; eclipses in history; techniques of observation; getting photographs; place and event for public observation. Over the years, direct contact was maintained with the media and jounralists by the press offices of the institutions.

A powerful test for weak periodic signals with unknown light curve shape in sparse data

International Nuclear Information System (INIS)

Jager De, O.C.; Raubenheimer, B.C.; Swanepoel, J.W.H.

1989-01-01

A problem with most tests for periodicity is that they are powerful enough to detect only certain kinds of periodic shapes in the case of weak signals. This causes a selection effect with the identification of weak periodic signals. A new test for uniformity called the H-test is derived for which the probability distribution is an exponential function. This test is shown to have a very good power against most light curve shapes encountered in X- and γ-ray Astronomy and therefore makes the detection of sources with a larger variety of shapes possible. The use of the H-test is suggested if no a priori information about the light curve shape is available. It is also shown how the probability distribution of the test statistics changes when a periodicity search is conducted using very small steps in the period or frequency range. The flux sensitivity for various light curve shapes is also derived for a few tests and this flux is on average a minimum for the H-test

THREE FUNDAMENTAL PERIODS IN AN 87 YEAR LIGHT CURVE OF THE SYMBIOTIC STAR MWC 560

Energy Technology Data Exchange (ETDEWEB)

Leibowitz, Elia M.; Formiggini, Liliana, E-mail: elia@astro.tau.ac.il [The Wise Observatory and the School of Physics and Astronomy, Raymond and Beverly Sackler Faculty of Exact Sciences, Tel Aviv University, Tel Aviv 69978 (Israel)

2015-08-15

We construct a visual light curve of the symbiotic star MWC covering the last 87 years of its history. The data were assembled from the literature and from the AAVSO data bank. Most of the periodic components of the system brightness variation can be accounted for by the operation of three basic clocks of the periods P1 = 19,000 days, P2 = 1943 days, and P3 = 722 days. These periods can plausibly, and consistently with the observations, be attributed to three physical mechanisms in the system: the working of a solar-like magnetic dynamo cycle in the outer layers of the giant star of the system, the binary orbit cycle, and the sidereal rotation cycle of the giant star. MWC 560 is the seventh symbiotic star with historical light curves that reveal similar basic characteristics of the systems. The light curves of all these stars are well interpreted on the basis of the current understanding of the physical processes that are the major sources of the optical luminosity of these symbiotic systems.

THREE FUNDAMENTAL PERIODS IN AN 87 YEAR LIGHT CURVE OF THE SYMBIOTIC STAR MWC 560

International Nuclear Information System (INIS)

Leibowitz, Elia M.; Formiggini, Liliana

2015-01-01

We construct a visual light curve of the symbiotic star MWC covering the last 87 years of its history. The data were assembled from the literature and from the AAVSO data bank. Most of the periodic components of the system brightness variation can be accounted for by the operation of three basic clocks of the periods P1 = 19,000 days, P2 = 1943 days, and P3 = 722 days. These periods can plausibly, and consistently with the observations, be attributed to three physical mechanisms in the system: the working of a solar-like magnetic dynamo cycle in the outer layers of the giant star of the system, the binary orbit cycle, and the sidereal rotation cycle of the giant star. MWC 560 is the seventh symbiotic star with historical light curves that reveal similar basic characteristics of the systems. The light curves of all these stars are well interpreted on the basis of the current understanding of the physical processes that are the major sources of the optical luminosity of these symbiotic systems

AGAINST THE WIND: RADIO LIGHT CURVES OF TYPE IA SUPERNOVAE INTERACTING WITH LOW-DENSITY CIRCUMSTELLAR SHELLS

Energy Technology Data Exchange (ETDEWEB)

Harris, Chelsea E.; Nugent, Peter E.; Kasen, Daniel N., E-mail: chelseaharris@berkeley.edu [Astronomy Department, University of California Berkeley, Berkeley, CA (United States)

2016-06-01

For decades a wide variety of observations spanning the radio through optical and on to the X-ray have attempted to uncover signs of type Ia supernovae (SNe Ia) interacting with a circumstellar medium (CSM). The goal of these studies is to constrain the nature of the hypothesized SN Ia mass-donor companion. A continuous CSM is typically assumed when interpreting observations of interaction. However, while such models have been successfully applied to core-collapse SNe, the assumption of continuity may not be accurate for SNe Ia, because shells of CSM could be formed by pre-supernova eruptions (novae). In this work, we model the interaction of SNe with a spherical, low-density, finite-extent CSM and create a suite of synthetic radio synchrotron light curves. We find that CSM shells produce sharply peaked light curves. We also identify a fiducial set of models that obey a common evolution and can be used to generate radio light curves for an interaction with an arbitrary shell. The relations obeyed by the fiducial models can be used to deduce CSM properties from radio observations; we demonstrate this by applying them to the nondetections of SN 2011fe and SN 2014J. Finally, we explore a multiple shell CSM configuration and describe its more complicated dynamics and the resultant radio light curves.

Educating the Public about the 2017 Total Solar Eclipse

Science.gov (United States)

Pasachoff, Jay M.

2017-01-01

On behalf of the International Astronomical Union's Working Group on Solar Eclipses, I have long worked to bring knowledge about eclipses and how to observe the safely to the people of the various countries from which partial, annular, or total solar eclipses are visible. In 2017, we have first a chance to educate the people of South America on the occasion of the February 26 annular eclipse through southern Chile and Argentina that is partial throughout almost the entire continent (and an eclipse workshop will be held February 22-24 in Esquel, Argentina: http://sion.frm.utn.edu.ar/WDEAII) and then a chance to educate the 300 million people of the United States and others in adjacent countries as far south as northern South America about the glories of totality and how to observe partial phases. Our website, a compendium of links to information about maps, safe observing, science, and more is at http://eclipses.info. We link to important mapping sites at EclipseWise.com, GreatAmericanEclipse.com, and http://xjubier.free.fr/en/site_pages/solar_eclipses/xSE_GoogleMap3.php?Ecl=+20170821&Acc=2&Umb=1&Lmt=1&Mag=1&Max=1, and information about cloudiness statistics at http://eclipsophile.com, as well as simulation sites at https://svs.gsfc.nasa.gov/cgi-bin/details.cgi?aid=4314 and http://eyes.jpl.nasa.gov. The American Astronomical Society's task force on the 2017 eclipse has a website at http://eclipse.aas.org. We are working to disseminate accurate information about how and why to observe the total solar eclipse, trying among other things to head off common misinformation about the hazards of looking at the sun at eclipses or otherwise. About 12 million Americans live within the 70-mile-wide band of totality, and we encourage others to travel into it, trying to make clear the difference between even a 99% partial eclipse and a total eclipse, with its glorious Baily's beads, diamond rings, and totality that on this occasion lasts between 2 minutes and 2 minutes 40 seconds

Binarity and Variable Stars in the Open Cluster NGC 2126

Science.gov (United States)

Chehlaeh, Nareemas; Mkrtichian, David; Kim, Seung-Lee; Lampens, Patricia; Komonjinda, Siramas; Kusakin, Anatoly; Glazunova, Ljudmila

2018-04-01

We present the results of an analysis of photometric time-series observations for NGC 2126 acquired at the Thai National Observatory (TNO) in Thailand and the Mount Lemmon Optical Astronomy Observatory (LOAO) in USA during the years 2004, 2013 and 2015. The main purpose is to search for new variable stars and to study the light curves of binary systems as well as the oscillation spectra of pulsating stars. NGC 2126 is an intermediate-age open cluster which has a population of stars inside the δ Scuti instability strip. Several variable stars are reported including three eclipsing binary stars, one of which is an eclipsing binary star with a pulsating component (V551 Aur). The Wilson-Devinney technique was used to analyze its light curves and to determine a new set of the system’s parameters. A frequency analysis of the eclipse-subtracted light curve was also performed. Eclipsing binaries which are members of open clusters are capable of delivering strong constraints on the cluster’s properties which are in turn useful for a pulsational analysis of their pulsating components. Therefore, high-resolution, high-quality spectra will be needed to derive accurate component radial velocities of the faint eclipsing binaries which are located in the field of NGC 2126. The new Devasthal Optical Telescope, suitably equipped, could in principle do this.

Light Curve Stability and Period Behavior of the Contact Binary TZ ...

Indian Academy of Sciences (India)

J. Astrophys. Astr. (2013) 34, 329–339 c Indian Academy of Sciences. Light Curve Stability and Period Behavior of the Contact. Binary TZ Boo. M. M. Elkhateeb1,2 & M. I. Nouh1,2,∗. 1National Research Institute of Astronomy and Geophysics, 11421 Helwan, Cairo, Egypt. 2Physics Department, College of Science, Northern ...

Light Curve Periodic Variability of Cyg X-1 using Jurkevich Method ...

Indian Academy of Sciences (India)

Abstract. The Jurkevich method is a useful method to explore periodic- ity in the unevenly sampled observational data. In this work, we adopted the method to the light curve of Cyg X-1 from 1996 to 2012, and found that there is an interesting period of 370 days, which appears in both low/hard and high/soft states.

Interacting Winds in Eclipsing Symbiotic Systems

Indian Academy of Sciences (India)

2016-01-27

Jan 27, 2016 ... Interacting Winds in Eclipsing Symbiotic Systems – The Case Study of EG Andromedae ... to obtain the physical parameters of a quiescent eclipsing symbiotic system. ... Articles are also visible in Web of Science immediately.

KIC 4552982: outbursts and pulsations in the longest-ever pseudo-continuous light curve of a ZZ Ceti

Directory of Open Access Journals (Sweden)

Bell K. J.

2015-01-01

Full Text Available KIC 4552982 was the first ZZ Ceti (hydrogen-atmosphere pulsating white dwarf identified to lie in the Kepler field, resulting in the longest pseudo-continuous light curve ever obtained for this type of variable star. In addition to the pulsations, this light curve exhibits stochastic episodes of brightness enhancement unlike any previously studied white dwarf phenomenon. We briefly highlight the basic outburst and pulsation properties in these proceedings.

SNaX: A Database of Supernova X-Ray Light Curves

Energy Technology Data Exchange (ETDEWEB)

Ross, Mathias; Dwarkadas, Vikram V., E-mail: Mathias_Ross@msn.com, E-mail: vikram@oddjob.uchicago.edu [Astronomy and Astrophysics, University of Chicago, 5640 S Ellis Avenue, ERC 569, Chicago, IL 60637 (United States)

2017-06-01

We present the Supernova X-ray Database (SNaX), a compilation of the X-ray data from young supernovae (SNe). The database includes the X-ray fluxes and luminosities of young SNe, from days to years after outburst. The original goal and intent of this study was to present a database of Type IIn SNe (SNe IIn), which we have accomplished. Our ongoing goal is to expand the database to include all SNe for which published data are available. The database interface allows one to search for SNe using various criteria, plot all or selected data points, and download both the data and the plot. The plotting facility allows for significant customization. There is also a facility for the user to submit data that can be directly incorporated into the database. We include an option to fit the decay of any given SN light curve with a power-law. The database includes a conversion of most data points to a common 0.3–8 keV band so that SN light curves may be directly compared with each other. A mailing list has been set up to disseminate information about the database. We outline the structure and function of the database, describe its various features, and outline the plans for future expansion.

THE CARNEGIE SUPERNOVA PROJECT: LIGHT-CURVE FITTING WITH SNooPy

International Nuclear Information System (INIS)

Burns, Christopher R.; Persson, S. E.; Madore, Barry F.; Freedman, Wendy L.; Stritzinger, Maximilian; Phillips, M. M.; Boldt, Luis; Campillay, Abdo; Folatelli, Gaston; Gonzalez, Sergio; Krzeminski, Wojtek; Morrell, Nidia; Salgado, Francisco; Kattner, ShiAnne; Contreras, Carlos; Suntzeff, Nicholas B.

2011-01-01

In providing an independent measure of the expansion history of the universe, the Carnegie Supernova Project (CSP) has observed 71 high-z Type Ia supernovae (SNe Ia) in the near-infrared bands Y and J. These can be used to construct rest-frame i-band light curves which, when compared to a low-z sample, yield distance moduli that are less sensitive to extinction and/or decline-rate corrections than in the optical. However, working with NIR observed and i-band rest-frame photometry presents unique challenges and has necessitated the development of a new set of observational tools in order to reduce and analyze both the low-z and high-z CSP sample. We present in this paper the methods used to generate uBVgriYJH light-curve templates based on a sample of 24 high-quality low-z CSP SNe. We also present two methods for determining the distances to the hosts of SN Ia events. A larger sample of 30 low-z SNe Ia in the Hubble flow is used to calibrate these methods. We then apply the method and derive distances to seven galaxies that are so nearby that their motions are not dominated by the Hubble flow.

SNaX: A Database of Supernova X-Ray Light Curves

International Nuclear Information System (INIS)

Ross, Mathias; Dwarkadas, Vikram V.

2017-01-01

We present the Supernova X-ray Database (SNaX), a compilation of the X-ray data from young supernovae (SNe). The database includes the X-ray fluxes and luminosities of young SNe, from days to years after outburst. The original goal and intent of this study was to present a database of Type IIn SNe (SNe IIn), which we have accomplished. Our ongoing goal is to expand the database to include all SNe for which published data are available. The database interface allows one to search for SNe using various criteria, plot all or selected data points, and download both the data and the plot. The plotting facility allows for significant customization. There is also a facility for the user to submit data that can be directly incorporated into the database. We include an option to fit the decay of any given SN light curve with a power-law. The database includes a conversion of most data points to a common 0.3–8 keV band so that SN light curves may be directly compared with each other. A mailing list has been set up to disseminate information about the database. We outline the structure and function of the database, describe its various features, and outline the plans for future expansion.

Type Ia Supernova Light Curve Inference: Hierarchical Models for Nearby SN Ia in the Optical and Near Infrared

Science.gov (United States)

Mandel, Kaisey; Kirshner, R. P.; Narayan, G.; Wood-Vasey, W. M.; Friedman, A. S.; Hicken, M.

2010-01-01

I have constructed a comprehensive statistical model for Type Ia supernova light curves spanning optical through near infrared data simultaneously. The near infrared light curves are found to be excellent standard candles (sigma(MH) = 0.11 +/- 0.03 mag) that are less vulnerable to systematic error from dust extinction, a major confounding factor for cosmological studies. A hierarchical statistical framework incorporates coherently multiple sources of randomness and uncertainty, including photometric error, intrinsic supernova light curve variations and correlations, dust extinction and reddening, peculiar velocity dispersion and distances, for probabilistic inference with Type Ia SN light curves. Inferences are drawn from the full probability density over individual supernovae and the SN Ia and dust populations, conditioned on a dataset of SN Ia light curves and redshifts. To compute probabilistic inferences with hierarchical models, I have developed BayeSN, a Markov Chain Monte Carlo algorithm based on Gibbs sampling. This code explores and samples the global probability density of parameters describing individual supernovae and the population. I have applied this hierarchical model to optical and near infrared data of over 100 nearby Type Ia SN from PAIRITEL, the CfA3 sample, and the literature. Using this statistical model, I find that SN with optical and NIR data have a smaller residual scatter in the Hubble diagram than SN with only optical data. The continued study of Type Ia SN in the near infrared will be important for improving their utility as precise and accurate cosmological distance indicators.

The Mystery and Beauty of Total Solar Eclipses

Indian Academy of Sciences (India)

ARTICLE. The Mystery and Beauty of Total Solar Eclipses. T Chandrasekhar is with the Astronomy and ..... Specialized instruments called coronagraphs, lo- cated at mountaintop ... Scientific studies of the solar eclipses began with the eclipse of. 1842 which ... a method simultaneously evolved by English spectroscopist.

Phase shifts and nonellipsoidal light curves: Challenges from mass determinations in x-ray binary stars

Science.gov (United States)

Cantrell, Andrew Glenn

We consider two types of anomalous observations which have arisen from efforts to measure dynamical masses of X-ray binary stars: (1) Radial velocity curves which seemingly show the primary and the secondary out of antiphase in most systems, and (2) The observation of double-waved light curves which deviate significantly from the ellipsoidal modulations expected for a Roche lobe filling star. We consider both problems with the joint goals of understanding the physical origins of the anomalous observations, and using this understanding to allow robust dynamical determinations of mass in X-ray binary systems. In our analysis of phase-shifted radial velocity curves, we discuss a comprehensive sample of X-ray binaries with published phase-shifted radial velocity curves. We show that the most commonly adopted explanation for phase shifts is contradicted by many observations, and consider instead a generalized form of a model proposed by Smak in 1970. We show that this model is well supported by a range of observations, including some systems which had previously been considered anomalous. We lay the groundwork for the derivation of mass ratios based on our explanation for phase shifts, and we discuss the work necessary to produce more detailed physical models of the phase shift. In our analysis of non-ellipsoidal light curves, we focus on the very well-studied system A0620-00. We present new VIH SMARTS photometry spanning 1999-2007, and supplement this with a comprehensive collection of archival data obtained since 1981. We show that A0620-00 undergoes optical state changes within X-ray quiescence and argue that not all quiescent data should be used for determinations of the inclination. We identify twelve light curves which may reliably be used for determining the inclination. We show that the accretion disk contributes significantly to all twelve curves and is the dominant source of nonellipsoidal variations. We derive the disk fraction for each of the twelve curves

TOWARD CHARACTERIZATION OF THE TYPE IIP SUPERNOVA PROGENITOR POPULATION: A STATISTICAL SAMPLE OF LIGHT CURVES FROM Pan-STARRS1

Energy Technology Data Exchange (ETDEWEB)

Sanders, N. E.; Soderberg, A. M.; Chornock, R.; Berger, E.; Challis, P.; Drout, M.; Kirshner, R. P.; Lunnan, R.; Marion, G. H.; Margutti, R.; McKinnon, R.; Milisavljevic, D. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Gezari, S. [Department of Astronomy, University of Maryland, College Park, MD 20742-2421 (United States); Betancourt, M. [Department of Statistics, University of Warwick, Coventry (United Kingdom); Foley, R. J. [Astronomy Department, University of Illinois at Urbana-Champaign, 1002 West Green Street, Urbana, IL 61801 (United States); Narayan, G. [National Optical Astronomy Observatory, 950 North Cherry Avenue, Tucson, AZ 85719 (United States); Rest, A. [Department of Physics and Astronomy, Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218 (United States); Kankare, E.; Mattila, S. [Finnish Centre for Astronomy with ESO (FINCA), University of Turku, Väisäläntie 20, 21500 Piikkiö (Finland); Smartt, S. J., E-mail: nsanders@cfa.harvard.edu [Astrophysics Research Centre, School of Mathematics and Physics, Queens University, BT7 1NN, Belfast (United Kingdom); and others

2015-02-01

In recent years, wide-field sky surveys providing deep multiband imaging have presented a new path for indirectly characterizing the progenitor populations of core-collapse supernovae (SNe): systematic light-curve studies. We assemble a set of 76 grizy-band Type IIP SN light curves from Pan-STARRS1, obtained over a constant survey program of 4 yr and classified using both spectroscopy and machine-learning-based photometric techniques. We develop and apply a new Bayesian model for the full multiband evolution of each light curve in the sample. We find no evidence of a subpopulation of fast-declining explosions (historically referred to as ''Type IIL'' SNe). However, we identify a highly significant relation between the plateau phase decay rate and peak luminosity among our SNe IIP. These results argue in favor of a single parameter, likely determined by initial stellar mass, predominantly controlling the explosions of red supergiants. This relation could also be applied for SN cosmology, offering a standardizable candle good to an intrinsic scatter of ≲ 0.2 mag. We compare each light curve to physical models from hydrodynamic simulations to estimate progenitor initial masses and other properties of the Pan-STARRS1 Type IIP SN sample. We show that correction of systematic discrepancies between modeled and observed SN IIP light-curve properties and an expanded grid of progenitor properties are needed to enable robust progenitor inferences from multiband light-curve samples of this kind. This work will serve as a pathfinder for photometric studies of core-collapse SNe to be conducted through future wide-field transient searches.

Apsidal motion of the eccentric eclipsing binary DI Herculis: An apparent discrepancy with general relativity

International Nuclear Information System (INIS)

Guinan, E.F.; Maloney, F.P.

1985-01-01

In 1959, Rudkjobing called attention to the 8th magnitude, eccentric eclipsing binary DI Herculis as an important test case for studying relativistic apsidal motion, since the theoretical relativistic apsidal motion is greater than that expected from the classical effects (i.e., from the tidal and rotational deformation of the stellar components). Excellent determinations of the orbital and stellar parameters of the system have been made by Popper (1982) from the combined analysis of the system's radial-velocity data and UBV light curves of Martynov and Khaliullin (1980), which permit the theoretical relativistic and classical components of the apsidal motion to be determined with reasonable certainty: omega-dot/sup theor//sub GR/ = 2X34/100 yr and omega-dot/sup theor//sub CL/ = 1X93/100 yr. Least-squares solutions of the timings of primary and secondary minima, extending over an 84-yr interval, and including eclipse timings obtained as recently as 1984, yield a small advance of periastron omega-dot/sup obs/ = 0X65/100 yr +- 0X18/100 yr. The observed advance of the periastron is about one-seventh the theoretical value of omega-dot/sup theor//sub GR+CL/ = 4X27/100 yr that is expected from the combined relativistic and classical effects, and results in a discrepancy of -3X62/100 yr, a value which has a magnitude of approx.20 sigma. Classical mechanisms that can possibly explain this apparent discrepancy are discussed, along with the possibility that there may be problems with general relativity

Listening to the solar eclipse with an educational tool for the blind and visually impaired

Science.gov (United States)

Bieryla, Allyson; Diaz-Merced, Wanda; Davis, Daniel; Hart, Robert

2018-01-01

The Great American Solar Eclipse took place on August 21, 2017 and swept through 14 of the United States. This was a highly publicized event and much of the world took notice. We live in a time where everything is accessible via the internet as it is happening. Many people, even those outside of the eclipse path, wanted to experience the event in real-time. We built a device, using an Arduino compatible microcontroller, that converts sunlight to sound so that the blind and visually impaired community could experience the eclipse live with the rest of the world. The device has a high dynamic range light sensor and an audio output that connects to a webcam and a computer. The event was successfully streamed to YouTube from Jackson Hole, Wyoming and people from all around the world connected to listen as the sun was temporarily dimmed by the eclipse of the moon. This device is inexpensive to reproduce (< $40 per device) and can be used as a teaching tool in a lab or classroom setting. Students can learn to build and write code for these devices as well. This is a tool with great potential for human development.

Revisiting the Energy Budget of WASP-43b: Enhanced Day–Night Heat Transport

Energy Technology Data Exchange (ETDEWEB)

Keating, Dylan; Cowan, Nicolas B. [Department of Physics, McGill University, 3600 rue University, Montréal, QC H3A 2T8 (Canada)

2017-11-01

The large day–night temperature contrast of WASP-43b has so far eluded explanation. We revisit the energy budget of this planet by considering the impact of reflected light on dayside measurements and the physicality of implied nightside temperatures. Previous analyses of the infrared eclipses of WASP-43b have assumed reflected light from the planet is negligible and can be ignored. We develop a phenomenological eclipse model including reflected light, thermal emission, and water absorption, and we use it to fit published Hubble and Spitzer eclipse data. We infer a near-infrared geometric albedo of 24% ± 1% and a cooler dayside temperature of 1483 ± 10 K. Additionally, we perform light curve inversion on the three published orbital phase curves of WASP-43b and find that each suggests unphysical, negative flux on the nightside. By requiring non-negative brightnesses at all longitudes, we correct the unphysical parts of the maps and obtain a much hotter nightside effective temperature of 1076 ± 11 K. The cooler dayside and hotter nightside suggest a heat recirculation efficiency of 51% for WASP-43b, essentially the same as for HD 209458b, another hot Jupiter with nearly the same temperature. Our analysis therefore reaffirms the trend that planets with lower irradiation temperatures have more efficient day–night heat transport. Moreover, we note that (1) reflected light may be significant for many near-IR eclipse measurements of hot Jupiters, and (2) phase curves should be fit with physically possible longitudinal brightness profiles—it is insufficient to only require that the disk-integrated light curve be non-negative.

Eclipse Science Results from the Airborne Infrared Spectrometer (AIR-Spec)

Science.gov (United States)

Samra, J.; Cheimets, P.; DeLuca, E.; Golub, L.; Judge, P. G.; Lussier, L.; Madsen, C. A.; Marquez, V.; Tomczyk, S.; Vira, A.

2017-12-01

We present the first science results from the commissioning flight of the Airborne Infrared Spectrometer (AIR-Spec), an innovative solar spectrometer that will observe the 2017 solar eclipse from the NSF/NCAR High-Performance Instrumented Airborne Platform for Environmental Research (HIAPER). During the eclipse, AIR-Spec will image five magnetically sensitive coronal emission lines between 1.4 and 4 microns to determine whether they may be useful probes of coronal magnetism. The instrument will measure emission line intensity, FWHM, and Doppler shift from an altitude of over 14 km, above local weather and most of the absorbing water vapor. Instrumentation includes an image stabilization system, feed telescope, grating spectrometer, infrared camera, and visible slit-jaw imager. Results from the 2017 eclipse are presented in the context of the mission's science goals. AIR-Spec will identify line strengths as a function of position in the solar corona and search for the high frequency waves that are candidates for heating and acceleration of the solar wind. The instrument will also identify large scale flows in the corona, particularly in polar coronal holes. Three of the five lines are expected to be strong in coronal hole plasmas because they are excited in part by scattered photospheric light. Line profile analysis will probe the origins of the fast and slow solar wind. Finally, the AIR-Spec measurements will complement ground based eclipse observations to provide detailed plasma diagnostics throughout the corona. AIR-Spec will measure infrared emission of ions observed in the visible from the ground, giving insight into plasma heating and acceleration at radial distances inaccessible to existing or planned spectrometers.

Characterizing the V-band light-curves of hydrogen-rich type II supernovae

DEFF Research Database (Denmark)

Anderson, Joseph P.; González-Gaitán, Santiago; Hamuy, Mario

2014-01-01

a dispersion of 0.56 mag, offering the prospect of using type II supernovae as purely photometric distance indicators. Our analysis suggests that the type II population spans a continuum from low-luminosity events which have flat light-curves during the "plateau" stage, through to the brightest events which...

Spitzer secondary eclipses of Qatar-1b

Science.gov (United States)

Garhart, Emily; Deming, Drake; Mandell, Avi; Knutson, Heather; Fortney, Jonathan J.

2018-02-01

Aims: Previous secondary eclipse observations of the hot Jupiter Qatar-1b in the Ks band suggest that it may have an unusually high day side temperature, indicative of minimal heat redistribution. There have also been indications that the orbit may be slightly eccentric, possibly forced by another planet in the system. We investigate the day side temperature and orbital eccentricity using secondary eclipse observations with Spitzer. Methods: We observed the secondary eclipse with Spitzer/IRAC in subarray mode, in both 3.6 and 4.5 μm wavelengths. We used pixel-level decorrelation to correct for Spitzer's intra-pixel sensitivity variations and thereby obtain accurate eclipse depths and central phases. Results: Our 3.6 μm eclipse depth is 0.149 ± 0.051% and the 4.5 μm depth is 0.273 ± 0.049%. Fitting a blackbody planet to our data and two recent Ks band eclipse depths indicates a brightness temperature of 1506 ± 71 K. Comparison to model atmospheres for the planet indicates that its degree of longitudinal heat redistribution is intermediate between fully uniform and day-side only. The day side temperature of the planet is unlikely to be as high (1885 K) as indicated by the ground-based eclipses in the Ks band, unless the planet's emergent spectrum deviates strongly from model atmosphere predictions. The average central phase for our Spitzer eclipses is 0.4984 ± 0.0017, yielding e cos ω = -0.0028 ± 0.0027. Our results are consistent with a circular orbit, and we constrain e cos ω much more strongly than has been possible with previous observations. Tables of the lightcurve data 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/A55

Light Curve Periodic Variability of Cyg X-1 using Jurkevich Method

Indian Academy of Sciences (India)

The Jurkevich method is a useful method to explore periodicity in the unevenly sampled observational data. In this work, we adopted the method to the light curve of Cyg X-1 from 1996 to 2012, and found that there is an interesting period of 370 days, which appears in both low/hard and high/soft states. That period may be ...

KEPLER'S OPTICAL SECONDARY ECLIPSE OF HAT-P-7b AND PROBABLE DETECTION OF PLANET-INDUCED STELLAR GRAVITY DARKENING

Energy Technology Data Exchange (ETDEWEB)

Morris, Brett M.; Deming, Drake [Department of Astronomy, University of Maryland, College Park, MD 20742 (United States); Mandell, Avi M. [Goddard Center for Astrobiology, NASA' s Goddard Space Flight Center, Greenbelt, MD 20771 (United States)

2013-02-20

We present observations spanning 355 orbital phases of HAT-P-7 observed by Kepler from 2009 May to 2011 March (Q1-9). We find a shallower secondary eclipse depth than initially announced, consistent with a low optical albedo and detection of nearly exclusively thermal emission, without a reflected light component. We find an approximately 10 ppm perturbation to the average transit light curve near phase -0.02 that we attribute to a temperature decrease on the surface of the star, phased to the orbit of the planet. This cooler spot is consistent with planet-induced gravity darkening, slightly lagging the sub-planet position due to the finite response time of the stellar atmosphere. The brightness temperature of HAT-P-7b in the Kepler bandpass is T{sub B} = 2733 {+-} 21 K and the amplitude of the deviation in stellar surface temperature due to gravity darkening is approximately -0.18 K. The detection of the spot is not statistically unequivocal due its small amplitude, though additional Kepler observations should be able to verify the astrophysical nature of the anomaly.

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

Light curve solutions and study of roles of magnetic fields in period variations of the UV Leo system

Directory of Open Access Journals (Sweden)

D Manzoori

2009-12-01

Full Text Available The solutions of photometric BV light curves for the Algol like system UV Leo were obtained using Wilson-Devinney code. The physical and orbital parameters along with absolute dimensions of the system were determined. It has been found that to best fit the V light curve of the system, assumptions of three dark spots were necessary two on the secondary and one on the primary. The absolute visual magnitudes (Mv of the individual components i.e., primary and secondary were estimated to 4.41 and 4.43, respectively, through the color curve analysis. The period analysis of the system presented elsewhere, indicated a cyclic period change of 12 yr duration, which was attributed to magnetic activity cycle, as a main cause of period variation in the system, through the Applegate mechanism. To verify the Applegate model I preformed calculations of some related parameters barrowed from Apllegate and Kalimeris. Values of all the calculated parameters were in accordance to those obtained for similar systems by Applegate. The differential magnitudes Δ B and Δ V, along with corresponding values of Δ(B-V color index. The cyclic variations in brightness are quite clear. There are three predictions of Applegate's theory concerning effects of cyclic magnetic changes on the period variations, which can be checked through the observations, these are as follows: I The long term variations in mean brightness (at outside of eclipses and cyclic changes of orbital period, vary with the same period. II The active star gets bluer as it gets brightened and/or the brightness and color variations are to be in phase. III Changes in luminosity due to changes in quadrupole moment should be of the order 0.1 mag. All the above mentioned predictions of Applegate’s theory are verified. These results combined with cyclic character of P(E presented elsewhere and also consistency of parameters which are obtained in this paper, led me to conclude that one the main causes of period

THE FIRST SYSTEMATIC STUDY OF TYPE Ibc SUPERNOVA MULTI-BAND LIGHT CURVES

International Nuclear Information System (INIS)

Drout, Maria R.; Soderberg, Alicia M.; Gal-Yam, Avishay; Arcavi, Iair; Green, Yoav; Cenko, S. Bradley; Fox, Derek B.; Leonard, Douglas C.; Sand, David J.; Moon, Dae-Sik

2011-01-01

We present detailed optical photometry for 25 Type Ibc supernovae (SNe Ibc) within d ≈ 150 Mpc obtained with the robotic Palomar 60 inch telescope in 2004-2007. This study represents the first uniform, systematic, and statistical sample of multi-band SNe Ibc light curves available to date. We correct the light curves for host galaxy extinction using a new technique based on the photometric color evolution, namely, we show that the (V – R) color of extinction-corrected SNe Ibc at Δt ≈ 10 days after V-band maximum is tightly distributed, ((V – R) V10 ) = 0.26 ± 0.06 mag. Using this technique, we find that SNe Ibc typically suffer from significant host galaxy extinction, (E(B – V)) ≈ 0.4 mag. A comparison of the extinction-corrected light curves for helium-rich (Type Ib) and helium-poor (Type Ic) SNe reveals that they are statistically indistinguishable, both in luminosity and decline rate. We report peak absolute magnitudes of (M R ) = –17.9 ± 0.9 mag and (M R ) = –18.3 ± 0.6 mag for SNe Ib and Ic, respectively. Focusing on the broad-lined (BL) SNe Ic, we find that they are more luminous than the normal SNe Ibc sample, (M R ) = –19.0 ± 1.1 mag, with a probability of only 1.6% that they are drawn from the same population of explosions. By comparing the peak absolute magnitudes of SNe Ic-BL with those inferred for local engine-driven explosions (GRB-SN 1998bw, XRF-SN 2006aj, and SN 2009bb) we find a 25% probability that relativistic SNe are drawn from the overall SNe Ic-BL population. Finally, we fit analytic models to the light curves to derive typical 56 Ni masses of M Ni ≈ 0.2 and 0.5 M ☉ for SNe Ibc and SNe Ic-BL, respectively. With reasonable assumptions for the photospheric velocities, we further extract kinetic energy and ejecta mass values of M ej ≈ 2 M ☉ and E K ≈ 10 51 erg for SNe Ibc, while for SNe Ic-BL we find higher values, M ej ≈ 5 M ☉ and E K ≈ 10 52 erg. We discuss the implications for the progenitors of SNe Ibc

The All-Sky Automated Survey for Supernovae (ASAS-SN) Light Curve Server v1.0

Science.gov (United States)

Kochanek, C. S.; Shappee, B. J.; Stanek, K. Z.; Holoien, T. W.-S.; Thompson, Todd A.; Prieto, J. L.; Dong, Subo; Shields, J. V.; Will, D.; Britt, C.; Perzanowski, D.; Pojmański, G.

2017-10-01

The All-Sky Automated Survey for Supernovae (ASAS-SN) is working toward imaging the entire visible sky every night to a depth of V˜ 17 mag. The present data covers the sky and spans ˜2-5 years with ˜100-400 epochs of observation. The data should contain some ˜1 million variable sources, and the ultimate goal is to have a database of these observations publicly accessible. We describe here a first step, a simple but unprecedented web interface https://asas-sn.osu.edu/ that provides an up to date aperture photometry light curve for any user-selected sky coordinate. The V band photometry is obtained using a two-pixel (16.″0) radius aperture and is calibrated against the APASS catalog. Because the light curves are produced in real time, this web tool is relatively slow and can only be used for small samples of objects. However, it also imposes no selection bias on the part of the ASAS-SN team, allowing the user to obtain a light curve for any point on the celestial sphere. We present the tool, describe its capabilities, limitations, and known issues, and provide a few illustrative examples.

The eclipse period of Escherichia coli

DEFF Research Database (Denmark)

von Freiesleben, Ulrik; Krekling, Martin A.; Hansen, Flemming G.

2000-01-01

corresponds to the period of origin hemimethylation. The SeqA protein was absolutely required for the eclipse, and DnaA titration studies suggested that the SeqA protein prevented the binding of multiple DnaA molecules on oriC (initial complex formation). No correlation between the amount of SeqA and eclipse...... length was revealed, but increased SeqA levels affected chromosome partitioning and/or cell division. This was corroborated further by an aberrant nucleoid distribution in SeqA-deficient cells. We suggest that the SeqA protein's role in maintaining the eclipse is tied to a function in chromosome...

The Discovery of Ellipsoidal Variations in the Kepler Light Curve of HAT-P-7

OpenAIRE

Welsh, William F.; Orosz, Jerome A.; Seager, Sara; Fortney, Jonathan J.; Jenkins, Jon; Rowe, Jason F.; Koch, David; Borucki, William J.

2010-01-01

We present an analysis of the early Kepler observations of the previously discovered transiting planet HAT-P-7b. The light curve shows the transit of the star, the occultation of the planet, and the orbit phase-dependent light from the planet. In addition, phase-dependent light from the star is present, known as "ellipsoidal variations". The very nearby planet (only 4 stellar radii away) gravitationally distorts the star and results in a flux modulation twice per orbit. The ellipsoidal variat...

Oscillating red giants in eclipsing binary systems: empirical reference value for asteroseismic scaling relation

Science.gov (United States)

Themeßl, N.; Hekker, S.; Southworth, J.; Beck, P. G.; Pavlovski, K.; Tkachenko, A.; Angelou, G. C.; Ball, W. H.; Barban, C.; Corsaro, E.; Elsworth, Y.; Handberg, R.; Kallinger, T.

2018-05-01

The internal structures and properties of oscillating red-giant stars can be accurately inferred through their global oscillation modes (asteroseismology). Based on 1460 days of Kepler observations we perform a thorough asteroseismic study to probe the stellar parameters and evolutionary stages of three red giants in eclipsing binary systems. We present the first detailed analysis of individual oscillation modes of the red-giant components of KIC 8410637, KIC 5640750 and KIC 9540226. We obtain estimates of their asteroseismic masses, radii, mean densities and logarithmic surface gravities by using the asteroseismic scaling relations as well as grid-based modelling. As these red giants are in double-lined eclipsing binaries, it is possible to derive their independent dynamical masses and radii from the orbital solution and compare it with the seismically inferred values. For KIC 5640750 we compute the first spectroscopic orbit based on both components of this system. We use high-resolution spectroscopic data and light curves of the three systems to determine up-to-date values of the dynamical stellar parameters. With our comprehensive set of stellar parameters we explore consistencies between binary analysis and asteroseismic methods, and test the reliability of the well-known scaling relations. For the three red giants under study, we find agreement between dynamical and asteroseismic stellar parameters in cases where the asteroseismic methods account for metallicity, temperature and mass dependence as well as surface effects. We are able to attain agreement from the scaling laws in all three systems if we use Δνref, emp = 130.8 ± 0.9 μHz instead of the usual solar reference value.

AN EXTREME ANALOGUE OF ϵ AURIGAE: AN M-GIANT ECLIPSED EVERY 69 YEARS BY A LARGE OPAQUE DISK SURROUNDING A SMALL HOT SOURCE

Energy Technology Data Exchange (ETDEWEB)

Rodriguez, Joseph E.; Stassun, Keivan G.; Lund, Michael B.; Conroy, Kyle E. [Department of Physics and Astronomy, Vanderbilt University, 6301 Stevenson Center, Nashville, TN 37235 (United States); Siverd, Robert J. [Las Cumbres Observatory Global Telescope Network, 6740 Cortona Drive, Suite 102, Santa Barbara, CA 93117 (United States); Pepper, Joshua [Department of Physics, Lehigh University, 16 Memorial Drive East, Bethlehem, PA 18015 (United States); Tang, Sumin [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Kafka, Stella [American Association of Variable Star Observers, 49 Bay State Road, Cambridge, MA 02138 (United States); Gaudi, B. Scott; Stevens, Daniel J.; Kochanek, Christopher S. [Department of Astronomy, The Ohio State University, Columbus, OH 43210 (United States); Beatty, Thomas G. [Department of Astronomy and Astrophysics, The Pennsylvania State University, 525 Davey Lab, University Park, PA 16802 (United States); Shappee, Benjamin J. [Carnegie Observatories, 813 Santa Barbara Street, Pasadena, CA 91101 (United States)

2016-05-01

We present TYC 2505-672-1 as a newly discovered and remarkable eclipsing system comprising an M-type red giant that undergoes a ∼3.45 year long, near-total eclipse (depth of ∼4.5 mag) with a very long period of ∼69.1 years. TYC 2505-672-1 is now the longest-period eclipsing binary system yet discovered, more than twice as long as that of the currently longest-period system, ϵ Aurigae. We show from analysis of the light curve including both our own data and historical data spanning more than 120 years and from modeling of the spectral energy distribution, both before and during eclipse, that the red giant primary is orbited by a moderately hot source ( T {sub eff} ≈ 8000 K) that is itself surrounded by an extended, opaque circumstellar disk. From the measured ratio of luminosities, the radius of the hot companion must be in the range of 0.1–0.5 R {sub ⊙} (depending on the assumed radius of the red giant primary), which is an order of magnitude smaller than that for a main sequence A star and 1–2 orders of magnitude larger than that for a white dwarf. The companion is therefore most likely a “stripped red giant” subdwarf-B type star destined to become a He white dwarf. It is, however, somewhat cooler than most sdB stars, implying a very low mass for this “pre-He-WD” star. The opaque disk surrounding this hot source may be a remnant of the stripping of its former hydrogen envelope. However, it is puzzling how this object became stripped, given that it is at present so distant (orbital semimajor axis of ∼24 au) from the current red giant primary star. Extrapolating from our calculated ephemeris, the next eclipse should begin in early UT 2080 April and end in mid UT 2083 September (eclipse center UT 2081 December 24). In the meantime, radial velocity observations would establish the masses of the components, and high-cadence UV observations could potentially reveal oscillations of the hot companion that would further constrain its evolutionary

Oscillatory patterns in the light curves of five long-term monitored type 1 active galactic nuclei

Science.gov (United States)

Kovačević, Andjelka B.; Pérez-Hernández, Ernesto; Popović, Luka Č.; Shapovalova, Alla I.; Kollatschny, Wolfram; Ilić, Dragana

2018-04-01

New combined data of five well-known type 1 active galactic nuclei (AGNs) are probed with a novel hybrid method in a search for oscillatory behaviour. Additional analysis of artificial light curves obtained from the coupled oscillatory models gives confirmation for detected periods that could have a physical background. We find periodic variations in the long-term light curves of 3C 390.3, NGC 4151 and NGC 5548, and E1821 + 643, with correlation coefficients larger than 0.6. We show that the oscillatory patterns of two binary black hole candidates, NGC 5548 and E1821 + 643, correspond to qualitatively different dynamical regimes of chaos and stability, respectively. We demonstrate that the absence of oscillatory patterns in Arp 102B could be the result of a weak coupling between oscillatory mechanisms. This is the first good evidence that 3C 390.3 and Arp 102B, categorized as double-peaked Balmer line objects, have qualitative different dynamics. Our analysis shows a novelty in the oscillatory dynamical patterns of the light curves of these type 1 AGNs.

PyTranSpot: A tool for multiband light curve modeling of planetary transits and stellar spots

Science.gov (United States)

Juvan, Ines G.; Lendl, M.; Cubillos, P. E.; Fossati, L.; Tregloan-Reed, J.; Lammer, H.; Guenther, E. W.; Hanslmeier, A.

2018-02-01

Several studies have shown that stellar activity features, such as occulted and non-occulted starspots, can affect the measurement of transit parameters biasing studies of transit timing variations and transmission spectra. We present PyTranSpot, which we designed to model multiband transit light curves showing starspot anomalies, inferring both transit and spot parameters. The code follows a pixellation approach to model the star with its corresponding limb darkening, spots, and transiting planet on a two dimensional Cartesian coordinate grid. We combine PyTranSpot with a Markov chain Monte Carlo framework to study and derive exoplanet transmission spectra, which provides statistically robust values for the physical properties and uncertainties of a transiting star-planet system. We validate PyTranSpot's performance by analyzing eleven synthetic light curves of four different star-planet systems and 20 transit light curves of the well-studied WASP-41b system. We also investigate the impact of starspots on transit parameters and derive wavelength dependent transit depth values for WASP-41b covering a range of 6200-9200 Å, indicating a flat transmission spectrum.

The Solar Eclipse Predictions of Chiljeongsam-Oepyeon in Early Choseon

Science.gov (United States)

Ahn, Young Sook; Lee, Yong Sam

2004-12-01

The history books of East Asia about astronomical phenomena have the more records of the solar eclipse frequently than any other ones. It is because traditionally, the solar eclipse meaned the fate of dynasty and the king's rule. The Sun, the biggest thing in the heaven symbolized the king, and the solar eclipse foresaw that the king had the problem in private including the body, and the country might suffer from difficulties in a great scale. So the king and all of the ministers used to gather to hold a ceremony named Gusikrye which solar eclipse may pass safely. Consequently, kings always had concernments on collecting informations of solar eclipse. Inspite of importance of solar eclipse predictions, but at the beginning of the Choseon, the predictions of the solar eclipse didn't fit. King Sejong compiled the Chiljeongsan-naepion and the Chiljeongsan-oepyeon to calculate the celestial phenomena including the solar eclipse. By the publications of these two books, the calendar making system of Choseon was firmly established. The Chiljeongsan-oepyeon adopted Huihui calendar of Arabia. The Solar eclipse predictions of Chiljeongsan-oepyeon were relative correct compared to modern method in early Choseon dynasty.

The Solar Eclipse Predictions of Chiljeongsam-Oepyeon in Early Choseon

Directory of Open Access Journals (Sweden)

Young Sook Ahn

2004-12-01

Full Text Available The history books of East Asia about astronomical phenomena have the more records of the solar eclipse frequently than any other ones. It is because traditionally, the solar eclipse meaned the fate of dynasty and the king's rule. The Sun, the biggest thing in the heaven symbolized the king, and the solar eclipse foresaw that the king had the problem in private including the body, and the country might suffer from difficulties in a great scale. So the king and all of the ministers used to gather to hold a ceremony named Gusikrye which solar eclipse may pass safely. Consequently, kings always had concernments on collecting informations of solar eclipse. Inspite of importance of solar eclipse predictions, but at the beginning of the Choseon, the predictions of the solar eclipse didn't fit. King Sejong compiled the Chiljeongsan-naepion and the Chiljeongsan-oepyeon to calculate the celestial phenomena including the solar eclipse. By the publications of these two books, the calendar making system of Choseon was firmly established. The Chiljeongsan-oepyeon adopted Huihui calendar of Arabia. The Solar eclipse predictions of Chiljeongsan-oepyeon were relative correct compared to modern method in early Choseon dynasty.

Eclipse journeys to the dark side of the Moon

CERN Document Server

Close, Frank

2017-01-01

On August 21st, over one hundred million people will gather across the USA to witness the most-watched total solar eclipse in history. Eclipse: Journeys to the Dark Side of the Moon, by popular science author Frank Close, describes the spellbinding allure of this beautiful natural phenomenon. The book explains why eclipses happen, reveals their role in history, literature and myth, and introduces us to eclipse chasers, who travel with ecstatic fervor to some of the most inaccessible places on the globe. The book also includes the author's quest to solve a 3000-year-old mystery: how did the moon move backward during a total solar eclipse, as claimed in the Book of Joshua? Eclipse is also the story of how a teacher inspired the author, aged eight, to pursue a career in science and a love affair with eclipses that has taken him to a war zone in the Western Sahara, the South Pacific, and the African bush. The tale comes full circle with another eight-year old boy - the author's grandson - at the 2017 great Americ...

Total Addiction The Life of an Eclipse Chaser

CERN Document Server

Russo, Kate

2012-01-01

Seeing a total solar eclipse is often described as a once-in-a-lifetime experience. However, for many who have experienced totality, once-in-a-lifetime is simply not enough. They want more, and are willing to go to great lengths often at great expense to repeat the experience. What is it like to experience totality? What is it about the experience that motivates these eclipse chasers? Is there an eclipse chaser personality? Can eclipse chasing actually be described as an addiction? This book describes the people who dedicate their lives to chasing their dream.

Dependence on supernovae light-curve processing in void models

Energy Technology Data Exchange (ETDEWEB)

Bengochea, Gabriel R., E-mail: gabriel@iafe.uba.ar [Instituto de Astronomía y Física del Espacio (IAFE), UBA-CONICET, CC 67, Suc. 28, 1428 Buenos Aires (Argentina); De Rossi, Maria E., E-mail: derossi@iafe.uba.ar [Instituto de Astronomía y Física del Espacio (IAFE), UBA-CONICET, CC 67, Suc. 28, 1428 Buenos Aires (Argentina); Departamento de Física, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires (Argentina)

2014-06-02

In this work, we show that when supernova Ia (SN Ia) data sets are used to put constraints on the free parameters of inhomogeneous models, certain extra information regarding the light-curve fitter used in the supernovae Ia luminosity fluxes processing should be taken into account. We found that the size of the void as well as other parameters of these models might be suffering extra degenerations or additional systematic errors due to the fitter. A recent proposal to relieve the tension between the results from Planck satellite and SNe Ia is re-analyzed in the framework of these subjects.

The EB factory project. II. Validation with the Kepler field in preparation for K2 and TESS

Energy Technology Data Exchange (ETDEWEB)

Parvizi, Mahmoud; Paegert, Martin; Stassun, Keivan G., E-mail: mahmoud.parvizi@vanderbilt.edu [Department of Physics and Astronomy, Vanderbilt University, VU Station B 1807, Nashville, TN 37235 (United States)

2014-12-01

Large repositories of high precision light curve data, such as the Kepler data set, provide the opportunity to identify astrophysically important eclipsing binary (EB) systems in large quantities. However, the rate of classical “by eye” human analysis restricts complete and efficient mining of EBs from these data using classical techniques. To prepare for mining EBs from the upcoming K2 mission as well as other current missions, we developed an automated end-to-end computational pipeline—the Eclipsing Binary Factory (EBF)—that automatically identifies EBs and classifies them into morphological types. The EBF has been previously tested on ground-based light curves. To assess the performance of the EBF in the context of space-based data, we apply the EBF to the full set of light curves in the Kepler “Q3” Data Release. We compare the EBs identified from this automated approach against the human generated Kepler EB Catalog of ∼2600 EBs. When we require EB classification with ⩾90% confidence, we find that the EBF correctly identifies and classifies eclipsing contact (EC), eclipsing semi-detached (ESD), and eclipsing detached (ED) systems with a false positive rate of only 4%, 4%, and 8%, while complete to 64%, 46%, and 32%, respectively. When classification confidence is relaxed, the EBF identifies and classifies ECs, ESDs, and EDs with a slightly higher false positive rate of 6%, 16%, and 8%, while much more complete to 86%, 74%, and 62%, respectively. Through our processing of the entire Kepler “Q3” data set, we also identify 68 new candidate EBs that may have been missed by the human generated Kepler EB Catalog. We discuss the EBF's potential application to light curve classification for periodic variable stars more generally for current and upcoming surveys like K2 and the Transiting Exoplanet Survey Satellite.

Eclipsing binary stars with a δ Scuti component

Science.gov (United States)

Kahraman Aliçavuş, F.; Soydugan, E.; Smalley, B.; Kubát, J.

2017-09-01

Eclipsing binaries with a δ Sct component are powerful tools to derive the fundamental parameters and probe the internal structure of stars. In this study, spectral analysis of six primary δ Sct components in eclipsing binaries has been performed. Values of Teff, v sin I, and metallicity for the stars have been derived from medium-resolution spectroscopy. Additionally, a revised list of δ Sct stars in eclipsing binaries is presented. In this list, we have only given the δ Sct stars in eclipsing binaries to show the effects of the secondary components and tidal-locking on the pulsations of primary δ Sct components. The stellar pulsation, atmospheric and fundamental parameters (e.g. mass, radius) of 92 δ Sct stars in eclipsing binaries have been gathered. Comparison of the properties of single and eclipsing binary member δ Sct stars has been made. We find that single δ Sct stars pulsate in longer periods and with higher amplitudes than the primary δ Sct components in eclipsing binaries. The v sin I of δ Sct components is found to be significantly lower than that of single δ Sct stars. Relationships between the pulsation periods, amplitudes and stellar parameters in our list have been examined. Significant correlations between the pulsation periods and the orbital periods, Teff, log g, radius, mass ratio, v sin I and the filling factor have been found.

Gamma-ray pulsar physics: gap-model populations and light-curve analyses in the Fermi era

International Nuclear Information System (INIS)

Pierbattista, M.

2010-01-01

This thesis research focusses on the study of the young and energetic isolated ordinary pulsar population detected by the Fermi gamma-ray space telescope. We compared the model expectations of four emission models and the LAT data. We found that all the models fail to reproduce the LAT detections, in particular the large number of high E objects observed. This inconsistency is not model dependent. A discrepancy between the radio-loud/radio-quiet objects ratio was also found between the observed and predicted samples. The L γ α E 0.5 relation is robustly confirmed by all the assumed models with particular agreement in the slot gap (SG) case. On luminosity bases, the intermediate altitude emission of the two pole caustic SG model is favoured. The beaming factor f Ω shows an E dependency that is slightly visible in the SG case. Estimates of the pulsar orientations have been obtained to explain the simultaneous gamma and radio light-curves. By analysing the solutions we found a relation between the observed energy cutoff and the width of the emission slot gap. This relation has been theoretically predicted. A possible magnetic obliquity α alignment with time is rejected -for all the models- on timescale of the order of 10 6 years. The light-curve morphology study shows that the outer magnetosphere gap emission (OGs) are favoured to explain the observed radio-gamma lag. The light curve moment studies (symmetry and sharpness) on the contrary favour a two pole caustic SG emission. All the model predictions suggest a different magnetic field layout with an hybrid two pole caustic and intermediate altitude emission to explain both the pulsar luminosity and light curve morphology. The low magnetosphere emission mechanism of the polar cap model, is systematically rejected by all the tests done. (author) [fr

PERIOD ESTIMATION FOR SPARSELY SAMPLED QUASI-PERIODIC LIGHT CURVES APPLIED TO MIRAS

Energy Technology Data Exchange (ETDEWEB)

He, Shiyuan; Huang, Jianhua Z.; Long, James [Department of Statistics, Texas A and M University, College Station, TX (United States); Yuan, Wenlong; Macri, Lucas M., E-mail: lmacri@tamu.edu [George P. and Cynthia W. Mitchell Institute for Fundamental Physics and Astronomy, Department of Physics and Astronomy, Texas A and M University, College Station, TX (United States)

2016-12-01

We develop a nonlinear semi-parametric Gaussian process model to estimate periods of Miras with sparsely sampled light curves. The model uses a sinusoidal basis for the periodic variation and a Gaussian process for the stochastic changes. We use maximum likelihood to estimate the period and the parameters of the Gaussian process, while integrating out the effects of other nuisance parameters in the model with respect to a suitable prior distribution obtained from earlier studies. Since the likelihood is highly multimodal for period, we implement a hybrid method that applies the quasi-Newton algorithm for Gaussian process parameters and search the period/frequency parameter space over a dense grid. A large-scale, high-fidelity simulation is conducted to mimic the sampling quality of Mira light curves obtained by the M33 Synoptic Stellar Survey. The simulated data set is publicly available and can serve as a testbed for future evaluation of different period estimation methods. The semi-parametric model outperforms an existing algorithm on this simulated test data set as measured by period recovery rate and quality of the resulting period–luminosity relations.

Spotted star light curve numerical modeling technique and its application to HII 1883 surface imaging

Science.gov (United States)

Kolbin, A. I.; Shimansky, V. V.

2014-04-01

We developed a code for imaging the surfaces of spotted stars by a set of circular spots with a uniform temperature distribution. The flux from the spotted surface is computed by partitioning the spots into elementary areas. The code takes into account the passing of spots behind the visible stellar limb, limb darkening, and overlapping of spots. Modeling of light curves includes the use of recent results of the theory of stellar atmospheres needed to take into account the temperature dependence of flux intensity and limb darkening coefficients. The search for spot parameters is based on the analysis of several light curves obtained in different photometric bands. We test our technique by applying it to HII 1883.

Configuration of and Motions in the Solar Corona at the 2017 Total Solar Eclipse

Science.gov (United States)

Pasachoff, Jay M.; Rusin, Vojtech; Vanur, Roman; Economou, Thanasis; Voulgaris, Aristeidis; Seiradakis, John H.; Seaton, Daniel; Dantowitz, Ronald; Lockwood, Christian A.; Nagle-McNaughton, Timothy; Perez, Cielo; Meadors, Erin N.; Marti, Connor J.; Yu, Ross; Rosseau, Brendan; Ide, Charles A.; Daly, Declan M.; Davis, Allen Bradford; Lu, Muzhou; Steele, Amy; Lee, Duane; Freeman, Marcus J.; Sliski, David; Rousseva, Ana; Greek Salem (Oregon) Team; Voulgaris, Aristeidis; Seiradakis, John Hugh; Koukioglou, Stavros; Kyriakou, Nikos; Vasileiadou, Anna; Greek Carbondale (Illinois) Team; Economou, Thanasis; Kanouras, Spyros; Irakleous, Christina; Golemis, Adrianos; Tsioumpanika, Nikoleta; Plexidas, Nikos; Tzimkas, Nikos; Kokkinidou, Ourania

2018-06-01

We report on high-contrast data reduction of white-light images from the August 21, 2017, total solar eclipse. We show the configuration of the solar corona at this declining phase of the solar-activity cycle, with the projection onto the plane of the sky of the three-dimensional coronal streamers plus extensive polar plumes. We discuss the relation of the white-light coronal loops visible in our observations with extreme-ultraviolet observations from NASA’s Solar Dynamics Observatory Atmospheric Imaging Assembly (AIA) and NOAA’s GOES-16 Solar Ultraviolet Imager (SUVI). We show differences and motions over a 65-minute interval between observations from our main site at Willamette University in Salem, Oregon, and a subsidiary site in Carbondale, Illinois. We discuss, in particular, a giant demarcation about 1 solar radius outward in the southwest that crosses the radial streamers.Our observations of the eclipse were sponsored in large part by the Committee for Research and Exploration of the National Geographic Society and by the Solar Terrestrial Program of the National Geographic Society. Additional support was received from the NASA Massachusetts Space Grant Consortium, the Sigma Xi honorary scientific society, the University of Pennsylvania (for DS), the Slovak Academy of Sciences VEGA project 2/0003/16, and the Freeman Foote Expeditionary and Brandi funds at Williams College. We thank Stephen Thorsett, Rick Watkins, and Honey Wilson of Willamette University for their hospitality. See http://totalsolareclipse.org or http://sites.williams.edu/eclipse/2017-usa/.

Star-spot distributions and chromospheric activity on the RS CVn type eclipsing binary SV Cam

Science.gov (United States)

Şenavcı, H. V.; Bahar, E.; Montes, D.; Zola, S.; Hussain, G. A. J.; Frasca, A.; Işık, E.; Yörükoǧlu, O.

2018-06-01

Using a time series of high-resolution spectra and high-quality multi-colour photometry, we reconstruct surface maps of the primary component of the RS CVn type rapidly rotating eclipsing binary, SV Cam (F9V + K4V). We measure a mass ratio, q, of 0.641(2) using our highest quality spectra and obtain surface brightness maps of the primary component, which exhibit predominantly high-latitude spots located between 60° - 70° latitudes with a mean filling factor of ˜35%. This is also indicated by the R-band light curve inversion, subjected to rigourous numerical tests. The spectral subtraction of the Hα line reveals strong activity of the secondary component. The excess Hα absorption detected near the secondary minimum hints to the presence of cool material partially obscuring the primary star. The flux ratios of Ca II IRT excess emission indicate that the contribution of chromospheric plage regions associated with star-spots is dominant, even during the passage of the filament-like absorption feature.

The first orbital parameters and period variation of the short-period eclipsing binary AQ Boo

Science.gov (United States)

Wang, Shuai; Zhang, Liyun; Pi, Qingfeng; Han, Xianming L.; Zhang, Xiliang; Lu, Hongpeng; Wang, Daimei; Li, TongAn

2016-10-01

We obtained the first VRI CCD light curves of the short-period contact eclipsing binary AQ Boo, which was observed on March 22 and April 19 in 2014 at Xinglong station of National Astronomical Observatories, and on January 20, 21 and February 28 in 2015 at Kunming station of Yunnan Observatories of Chinese Academy of Sciences, China. Using our six newly obtained minima and the minima that other authors obtained previously, we revised the ephemeris of AQ Boo. By fitting the O-C (observed minus calculated) values of the minima, the orbital period of AQ Boo shows a decreasing tendency P˙ = - 1.47(0.17) ×10-7 days/year. We interpret the phenomenon by mass transfer from the secondary (more massive) component to the primary (less massive) one. By using the updated Wilson & Devinney program, we also derived the photometric orbital parameters of AQ Boo for the first time. We conclude that AQ Boo is a near contact binary with a low contact factor of 14.43%, and will become an over-contact system as the mass transfer continues.

An Empirical Fitting Method for Type Ia Supernova Light Curves: A Case Study of SN 2011fe

Energy Technology Data Exchange (ETDEWEB)

Zheng, WeiKang; Filippenko, Alexei V., E-mail: zwk@astro.berkeley.edu [Department of Astronomy, University of California, Berkeley, CA 94720-3411 (United States)

2017-03-20

We present a new empirical fitting method for the optical light curves of Type Ia supernovae (SNe Ia). We find that a variant broken-power-law function provides a good fit, with the simple assumption that the optical emission is approximately the blackbody emission of the expanding fireball. This function is mathematically analytic and is derived directly from the photospheric velocity evolution. When deriving the function, we assume that both the blackbody temperature and photospheric velocity are constant, but the final function is able to accommodate these changes during the fitting procedure. Applying it to the case study of SN 2011fe gives a surprisingly good fit that can describe the light curves from the first-light time to a few weeks after peak brightness, as well as over a large range of fluxes (∼5 mag, and even ∼7 mag in the g band). Since SNe Ia share similar light-curve shapes, this fitting method has the potential to fit most other SNe Ia and characterize their properties in large statistical samples such as those already gathered and in the near future as new facilities become available.

Artificial Intelligence in Astronomy

Science.gov (United States)

Devinney, E. J.; Prša, A.; Guinan, E. F.; Degeorge, M.

2010-12-01

From the perspective (and bias) as Eclipsing Binary researchers, we give a brief overview of the development of Artificial Intelligence (AI) applications, describe major application areas of AI in astronomy, and illustrate the power of an AI approach in an application developed under the EBAI (Eclipsing Binaries via Artificial Intelligence) project, which employs Artificial Neural Network technology for estimating light curve solution parameters of eclipsing binary systems.

HD 144548: A young triply eclipsing system in the Upper Scorpius OB association

Science.gov (United States)

Alonso, R.; Deeg, H. J.; Hoyer, S.; Lodieu, N.; Palle, E.; Sanchis-Ojeda, R.

2015-12-01

The star HD 144548 (=HIP 78977; TYP 6212-1273-1) has been known as a detached eclipsing binary and a bona-fide member of the Upper Scorpius OB association. Continuous photometry from the K2 mission on Campaign Two has revealed the presence of additional eclipses due to the presence of a third star in the system. These are explained by a system composed of the two previously known members of the eclipsing system (Ba and Bb) with a period of 1.63 d, orbiting around an F7-F8V star with a period of 33.945 ± 0.002 d in an eccentric orbit (eA = 0.2652 ± 0.0003). The timing of the eclipses of Ba and Bb reveals the same 33.9 d periodicity, which we interpret as the combination of a light time effect combined with dynamical perturbations on the close system. Here we combine radial velocities and analytical approximations for the timing of the eclipses to derive masses and radii for the three components of the system. We obtain a mass of 1.44 ± 0.04 M⊙ and radius of 2.41 ± 0.03 R⊙ for the A component, and almost identical masses and radii of about 0.96 M⊙ and 1.33 R⊙ for each of the two components of the close binary. HD 144548 is the first triply eclipsing system for which radial velocities of all components could be measured. Partially based on observations made with the Italian Telescopio Nazionale Galileo (TNG) operated by the Fundación Galileo Galilei of the INAF, the Nordic Optical Telescope, operated by the Nordic Optical Telescope Scientific Association, and the William Herschel Telescope (programme DDT58 - PI Lodieu) operated by the Isaac Newton Group on the island of La Palma at the Spanish Observatorio Roque de los Muchachos of the IAC. This paper includes data collected by the Kepler mission. Funding for the Kepler mission is provided by the NASA Science Mission directorate.Appendices are available in electronic form at http://www.aanda.org

Photometric solution and frequency analysis of the oEA system EW Boo

International Nuclear Information System (INIS)

Zhang, X. B.; Wang, K.; Luo, Y. P.

2015-01-01

We present the first photometric solution and frequency analysis of the neglected oscillating Algol-type (oEA) binary EW Boo. B- and V-band light curves of the star were obtained on 11 nights in 2014. Using the Wilson–Devinney code, the eclipsing light curves were synthesized and the first photometric solution was derived for the binary system. The results reveal that EW Boo could be a semi-detached system with the less-massive secondary component filling its Roche lobe. By subtracting the eclipsing light changes from the data, we obtained the intrinsic pulsating light curves of the hotter, massive primary component. Frequency analysis of residual light shows multi-mode pulsation with the dominant period at 0.01909 days. A preliminary mode identification suggests that the star could be pulsating in non-radial (l = 1) modes. The long-term orbital period variation of the system was also investigated for the first time. An improved orbital period and new ephemerides of the eclipsing binary are given. The O−C analysis indicates a secular period increasing at a rate of dP/dt=2.9×10 −7 days yr −1 , which could be interpreted as mass transfer from the cooler secondary to the primary component.

The diverse broad-band light-curves of Swift GRBs reproduced with the cannonball model

CERN Document Server

Dado, Shlomo; De Rújula, A

2009-01-01

Two radiation mechanisms, inverse Compton scattering (ICS) and synchrotron radiation (SR), suffice within the cannonball (CB) model of long gamma ray bursts (LGRBs) and X-ray flashes (XRFs) to provide a very simple and accurate description of their observed prompt emission and afterglows. Simple as they are, the two mechanisms and the burst environment generate the rich structure of the light curves at all frequencies and times. This is demonstrated for 33 selected Swift LGRBs and XRFs, which are well sampled from early time until late time and well represent the entire diversity of the broad band light curves of Swift LGRBs and XRFs. Their prompt gamma-ray and X-ray emission is dominated by ICS of glory light. During their fast decline phase, ICS is taken over by SR which dominates their broad band afterglow. The pulse shape and spectral evolution of the gamma-ray peaks and the early-time X-ray flares, and even the delayed optical `humps' in XRFs, are correctly predicted. The canonical and non-canonical X-ra...

Light, Gravity and Black Holes

Science.gov (United States)

Falla, David

2012-01-01

The nature of light and how it is affected by gravity is discussed. Einstein's prediction of the deflection of light as it passes near the Sun was verified by observations made during the solar eclipse of 1919. Another prediction was that of gravitational redshift, which occurs when light emitted by a star loses energy in the gravitational field…

BINARY CANDIDATES IN THE JOVIAN TROJAN AND HILDA POPULATIONS FROM NEOWISE LIGHT CURVES

Energy Technology Data Exchange (ETDEWEB)

Sonnett, S.; Mainzer, A.; Masiero, J.; Bauer, J. [Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 (United States); Grav, T., E-mail: Sarah.Sonnett@jpl.nasa.gov [Planetary Science Institute, Tucson, AZ (United States)

2015-02-01

Determining the binary fraction for a population of asteroids, particularly as a function of separation between the two components, helps describe the dynamical environment at the time the binaries formed, which in turn offers constraints on the dynamical evolution of the solar system. We searched the NEOWISE archival data set for close and contact binary Trojans and Hildas via their diagnostically large light curve amplitudes. We present 48 out of 554 Hilda and 34 out of 953 Trojan binary candidates in need of follow-up to confirm their large light curve amplitudes and subsequently constrain the binary orbit and component sizes. From these candidates, we calculate a preliminary estimate of the binary fraction without confirmation or debiasing of 14%-23% for Trojans larger than ∼12 km and 30%-51% for Hildas larger than ∼4 km. Once the binary candidates have been confirmed, it should be possible to infer the underlying, debiased binary fraction through estimation of survey biases.

LBT Discovery of a Yellow Supergiant Eclipsing Binary in the Dwarf Galaxy Holmberg IX

Science.gov (United States)

Prieto, J. L.; Stanek, K. Z.; Kochanek, C. S.; Weisz, D. R.; Baruffolo, A.; Bechtold, J.; Burwitz, V.; De Santis, C.; Gallozzi, S.; Garnavich, P. M.; Giallongo, E.; Hill, J. M.; Pogge, R. W.; Ragazzoni, R.; Speziali, R.; Thompson, D. J.; Wagner, R. M.

2008-01-01

In a variability survey of M81 using the Large Binocular Telescope we have discovered a peculiar eclipsing binary (MV ~ - 7.1) in the field of the dwarf galaxy Holmberg IX. It has a period of 271 days, and the light curve is well fit by an overcontact model in which both stars are overflowing their Roche lobes. It is composed of two yellow supergiants (V - Isimeq 1 mag, Teffsimeq 4800 K), rather than the far more common red or blue supergiants. Such systems must be rare. While we failed to find any similar systems in the literature, we did, however, note a second example. The SMC F0 supergiant R47 is a bright (MV ~ - 7.5) periodic variable whose All Sky Automated Survey (ASAS) light curve is well fit as a contact binary with a 181 day period. We propose that these systems are the progenitors of supernovae like SN 2004et and SN 2006ov, which appeared to have yellow progenitors. The binary interactions (mass transfer, mass loss) limit the size of the supergiant to give it a higher surface temperature than an isolated star at the same core evolutionary stage. We also discuss the possibility of this variable being a long-period Cepheid. Based on data acquired using the Large Binocular Telescope (LBT). The LBT is an international collaboration among institutions in the United States, Italy and Germany. LBT Corporation partners are The University of Arizona on behalf of the Arizona university system; Istituto Nazionale di Astrofisica, Italy; LBT Beteiligungsgesellschaft, Germany, representing the Max-Planck Society, the Astrophysical Institute Potsdam, and Heidelberg University; The Ohio State University, and The Research Corporation, on behalf of The University of Notre Dame, University of Minnesota, and University of Virginia.

A survey of eight hot Jupiters in secondary eclipse using WIRCam at CFHT

Science.gov (United States)

Martioli, Eder; Colón, Knicole D.; Angerhausen, Daniel; Stassun, Keivan G.; Rodriguez, Joseph E.; Zhou, George; Gaudi, B. Scott; Pepper, Joshua; Beatty, Thomas G.; Tata, Ramarao; James, David J.; Eastman, Jason D.; Wilson, Paul Anthony; Bayliss, Daniel; Stevens, Daniel J.

2018-03-01

We present near-infrared high-precision photometry for eight transiting hot Jupiters observed during their predicted secondary eclipses. Our observations were carried out using the staring mode of the WIRCam instrument on the Canada-France-Hawaii Telescope (CFHT). We present the observing strategies and data reduction methods which delivered time series photometry with statistical photometric precision as low as 0.11 per cent. We performed a Bayesian analysis to model the eclipse parameters and systematics simultaneously. The measured planet-to-star flux ratios allowed us to constrain the thermal emission from the day side of these hot Jupiters, as we derived the planet brightness temperatures. Our results combined with previously observed eclipses reveal an excess in the brightness temperatures relative to the blackbody prediction for the equilibrium temperatures of the planets for a wide range of heat redistribution factors. We find a trend that this excess appears to be larger for planets with lower equilibrium temperatures. This may imply some additional sources of radiation, such as reflected light from the host star and/or thermal emission from residual internal heat from the formation of the planet.

CHARACTERIZATION OF THE X-RAY LIGHT CURVE OF THE {gamma} Cas-LIKE B1e STAR HD 110432

Energy Technology Data Exchange (ETDEWEB)

Smith, Myron A. [Catholic University of America, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Lopes de Oliveira, Raimundo [Departamento de Fisica, Universidade Federal de Sergipe, Av. Marechal Rondon s/n, 49100-000 Sao Cristovao, SE (Brazil); Motch, Christian, E-mail: msmith@stsci.edu [Observatoire Astronomique, Universite de Strasbourg, CNRS UMR 7550, 11 rue de l' Universite, F-67000 Strasbourg (France)

2012-08-10

HD 110432 (BZ Cru; B1Ve) is the brightest member of a small group of '{gamma} Cas analogs' that emit copious hard X-ray flux, punctuated by ubiquitous 'flares'. To characterize the X-ray time history of this star, we made a series of six RXTE multi-visit observations in 2010 and an extended observation with the XMM-Newton in 2007. We analyzed these new light curves along with three older XMM-Newton observations from 2002 to 2003. Distributed over five months, the RXTE observations were designed to search for long X-ray modulations over a few months. These observations indeed suggest the presence of a long cycle with P Almost-Equal-To 226 days and an amplitude of a factor of two. We also used X-ray light curves constructed from XMM-Newton observations to characterize the lifetimes, strengths, and interflare intervals of 1615 flare-like events in the light curves. After accounting for false positive events, we infer the presence of 955 (2002-2003) and 386 (2007) events we identified as flares. Similarly, as a control we measured the same attributes for an additional group of 541 events in XMM-Newton light curves of {gamma} Cas, which, after a similar correction, yielded 517 flares. We found that the flare properties of HD 110432 are mostly similar to our control group. In both cases the distribution of flare strengths are best fit with log-linear relations. Both the slopes of these distributions and the flaring frequencies themselves exhibit modest fluctuations. We discovered that some flares in the hard X-ray band of HD 110432 were weak or unobserved in the soft band and vice versa. The light curves also occasionally show rapid curve drop-offs that are sustained for hours. We discuss the existence of the long cycle and these flare properties in the backdrop of two rival scenarios to produce hard X-rays, a magnetic star-disk interaction, and the accretion of blobs onto a secondary white dwarf.

The Infrared Light Curve of SN 2011fe in M101 and the Distance to M101

OpenAIRE

Matheson, T.; Joyce, R. R.; Allen, L. E.; Saha, A.; Silva, D. R.; Wood-Vasey, W. M.; Adams, J. J.; Anderson, R. E.; Beck, T. L.; Bentz, M. C.; Bershady, M. A.; Binkert, W. S.; Butler, K.; Camarata, M. A.; Eigenbrot, A.

2012-01-01

We present near infra-red light curves of supernova (SN) 2011fe in M101, including 34 epochs in H band starting fourteen days before maximum brightness in the B-band. The light curve data were obtained with the WIYN High-Resolution Infrared Camera (WHIRC). When the data are calibrated using templates of other Type Ia SNe, we derive an apparent H-band magnitude at the epoch of B-band maximum of 10.85 \\pm 0.04. This implies a distance modulus for M101 that ranges from 28.86 to 29.17 mag, depend...

On the mean profiles of radio pulsars - II. Reconstruction of complex pulsar light curves and other new propagation effects

Science.gov (United States)

Hakobyan, H. L.; Beskin, V. S.; Philippov, A. A.

2017-08-01

Our previous paper outlined the general aspects of the theory of radio light curve and polarization formation for pulsars. We predicted the one-to-one correspondence between the tilt of the linear polarization position angle of the the circular polarization. However, some of the radio pulsars indicate a clear deviation from that correlation. In this paper, we apply the theory of the radio wave propagation in the pulsar magnetosphere for the analysis of individual effects leading to these deviations. We show that within our theory the circular polarization of a given mode can switch its sign, without the need to introduce a new radiation mode or other effects. Moreover, we show that the generation of different emission modes on different altitudes can explain pulsars, that presumably have the X-O-X light-curve pattern, different from what we predict. General properties of radio emission within our propagation theory are also discussed. In particular, we calculate the intensity patterns for different radiation altitudes and present light curves for different observer viewing angles. In this context we also study the light curves and polarization profiles for pulsars with interpulses. Further, we explain the characteristic width of the position angle curves by introducing the concept of a wide emitting region. Another important feature of radio polarization profiles is the shift of the position angle from the centre, which in some cases demonstrates a weak dependence on the observation frequency. Here we demonstrate that propagation effects do not necessarily imply a significant frequency-dependent change of the position angle curve.

The X-Ray Light Curve of the Very Luminous Supernova SN 1978K in NGC 1313

Science.gov (United States)

Schlegel, Eric M.; Petre, R.; Colbert, E. J. M.

1996-01-01

We present the 0.5-2.0 keV light curve of the X-ray luminous supernova SN 1978K in NGC 1313, based on six ROSAT observations spanning 1990 July to t994 July. SN 1978K is one of a few supernovae or supernova remnants that are very luminous (˜1039-1040 ergs s-1) in the X-ray, optical, and radio bands, and the first, at a supernova age of 10-20 yr, for which sufficient data exist to create an X-ray light curve. The X-ray flux is approximately constant over the 4 yr sampled by our observations, which were obtained 12-16 yr after the initial explosion. Three models exist to explain the large X-ray luminosity: pulsar input, a reverse shock running back into the expanding debris of the supernova, and the outgoing shock crushing of cloudlets in the debris field. Based upon calculations of Chevalier & Fransson, a pulsar cannot provide sufficient energy to produce the soft X-ray luminosity. Based upon the models and the light curve to date, it is not possible to discern the evolutionary phase of the supernova.

Statistical analysis of geomagnetic field variations during solar eclipses

Science.gov (United States)

Kim, Jung-Hee; Chang, Heon-Young

2018-04-01

We investigate the geomagnetic field variations recorded by INTERMAGNET geomagnetic observatories, which are observed while the Moon's umbra or penumbra passed over them during a solar eclipse event. Though it is generally considered that the geomagnetic field can be modulated during solar eclipses, the effect of the solar eclipse on the observed geomagnetic field has proved subtle to be detected. Instead of exploring the geomagnetic field as a case study, we analyze 207 geomagnetic manifestations acquired by 100 geomagnetic observatories during 39 solar eclipses occurring from 1991 to 2016. As a result of examining a pattern of the geomagnetic field variation on average, we confirm that the effect can be seen over an interval of 180 min centered at the time of maximum eclipse on a site of a geomagnetic observatory. That is, demonstrate an increase in the Y component of the geomagnetic field and decreases in the X component and the total strength of the geomagnetic field. We also find that the effect can be overwhelmed, depending more sensitively on the level of daily geomagnetic events than on the level of solar activity and/or the phase of solar cycle. We have demonstrated it by dividing the whole data set into subsets based on parameters of the geomagnetic field, solar activity, and solar eclipses. It is suggested, therefore, that an evidence of the solar eclipse effect can be revealed even at the solar maximum, as long as the day of the solar eclipse is magnetically quiet.

High-precision 2MASS JHK{sub s} light curves and other data for RR Lyrae star SDSS J015450 + 001501: Strong constraints for nonlinear pulsation models

Energy Technology Data Exchange (ETDEWEB)

Szabó, Róbert; Ivezić, Željko; Kiss, László L.; Kolláth, Zoltán [Konkoly Observatory, MTA CSFK, Konkoly Thege Miklós út 15-17, H-1121 Budapest (Hungary); Jones, Lynne; Becker, Andrew C.; Davenport, James R. A. [Astronomy Department, University of Washington, Box 351580, Seattle, WA 98195-1580 (United States); Sesar, Branimir [Division of Physics, Mathematics and Astronomy, Caltech, Pasadena, CA 91125 (United States); Cutri, Roc M., E-mail: rszabo@konkoly.hu [Infrared Processing and Analysis Center, California Institute of Technology, Pasadena, CA 91125 (United States)

2014-01-01

We present and discuss an extensive data set for the non-Blazhko ab-type RR Lyrae star SDSS J015450+001501, including optical Sloan Digital Sky Survey ugriz light curves and spectroscopic data, LINEAR and Catalina Sky Survey unfiltered optical light curves, and infrared Two Micron All Sky Survey (2MASS) JHK{sub s} and Wide-field Infrared Survey Explorer W1 and W2 light curves. Most notable is that light curves obtained by 2MASS include close to 9000 photometric measures collected over 3.3 yr and provide an exceedingly precise view of near-infrared variability. These data demonstrate that static atmosphere models are insufficient to explain multiband photometric light-curve behavior and present strong constraints for nonlinear pulsation models for RR Lyrae stars. It is a challenge to modelers to produce theoretical light curves that can explain data presented here, which we make publicly available.

Efficient dye-sensitized solar cells from curved silicate microsheet caged TiO2 photoanodes. An avenue of enhancing light harvesting

International Nuclear Information System (INIS)

Wang, Zubin; Tang, Qunwei; He, Benlin; Chen, Haiyan; Yu, Liangmin

2015-01-01

Graphical abstract: - Highlights: • Curved silicate microsheets are incorporated with TiO 2 for light harvesting in DSSC • The optical matching between silicate and TiO 2 is superior to light reflection. • The curved silicate can hinder the recombination reaction of electrons with I 3 − . • The DSSC with TiO 2 /curved silicate photoanode shows an efficiency of 9.22% - Abstract: Enhancement of light harvesting has been a persistent objective for elevating dye excitation and therefore power conversion efficiency of dye-sensitized solar cells (DSSCs). Here we launch a strategy of markedly enhancing light harvesting by caging TiO 2 nanoparticles with curved silica microsheets. The results show that the strategy is versatile in suppressing the recombination reaction of electrons with I 3 − species in liquid electrolyte. Due to the superior reflective behaviors of curved silica microsheets, an optimal efficiency of 9.22% is recorded under simulated air mass 1.5 global sunlight on the DSSC in comparison with 6.51% and 7.51% from pristine TiO 2 and planar silicate microsheet incorporated TiO 2 photoanode based solar cells, respectively. This strategy is also believed to be applicable to other solar cells such as perovskite solar cells and quantum dot-sensitized solar cells.

Lunar eclipses: Probing the atmosphere of an inhabited planet

Science.gov (United States)

García Muñoz, A.

2013-04-01

The Moon's brightness during a lunar eclipse is indicative of the composition, cloudiness and aerosol loading of the Earth's atmosphere. The idea of using lunar eclipse observations to characterize the Earth's atmosphere is not new, but the interest raised by the prospects of discovering Earth-like exoplanets transiting their host stars has brought renewed attention to the method. We review some recent efforts made in the prediction and interpretation of lunar eclipses. We also comment on the contribution of the lunar eclipse theory to the refractive theory of planetary transits.

Lunar eclipses: Probing the atmosphere of an inhabited planet

Directory of Open Access Journals (Sweden)

Muñoz A. García

2013-04-01

Full Text Available The Moon's brightness during a lunar eclipse is indicative of the composition, cloudiness and aerosol loading of the Earth's atmosphere. The idea of using lunar eclipse observations to characterize the Earth's atmosphere is not new, but the interest raised by the prospects of discovering Earth-like exoplanets transiting their host stars has brought renewed attention to the method. We review some recent efforts made in the prediction and interpretation of lunar eclipses. We also comment on the contribution of the lunar eclipse theory to the refractive theory of planetary transits.

Eclipses and dust formation by WC9 type Wolf-Rayet stars

Science.gov (United States)

Williams, P. M.

2014-12-01

Visual photometry of 16 WC8-9 dust-making Wolf-Rayet (WR) stars during 2001-2009 was extracted from the All-Sky Automated Survey All Star Catalogue (ASAS-3) to search for eclipses attributable to extinction by dust formed in clumps in our line of sight. Data for a comparable number of dust-free WC6-9 stars were also examined to help characterize the data set. Frequent eclipses were observed from WR 104, and several from WR 106, extending the 1994-2001 studies by Kato et al., but not supporting their phasing the variations in WR 104 with its `pinwheel' rotation period. Only four other stars showed eclipses, WR 50 (one of the dust-free stars), WR 69, WR 95 and WR 117, and there may have been an eclipse by WR 121, which had shown two eclipses in the past. No dust eclipses were shown by the `historic' eclipsers WR 103 and WR 113. The atmospheric eclipses of the latter were observed but the suggestion by David-Uraz et al. that dust may be partly responsible for these is not supported. Despite its frequent eclipses, there is no evidence in the infrared images of WR 104 for dust made in its eclipses, demonstrating that any dust formed in this process is not a significant contributor to its circumstellar dust cloud and suggesting that the same applies to the other stars showing fewer eclipses.

A Coral Sea Rehearsal for the Eclipse Megamovie

Science.gov (United States)

Hudson, H. S.; Davey, A. R.; Ireland, J.; Jones, L.; Mcintosh, S. W.; Paglierani, R.; Pasachoff, J. M.; Peticolas, L. M.; Russell, R. M.; Suarez Sola, F. I.; Sutherland, L.; Thompson, M. J.

2012-12-01

The "Eclipse on the Coral Sea" - 13/14 November 2012 (GMT/Australia) - will have happened already. Our intention is to have used this opportunity as a trial run for the eclipse in 2017, which features 1.5 hours of totality across the whole width of the continental US. Conceived first and foremost as an education and public outreach activity, the plan is to engage the public in solar science and technology by providing a way for them to include images they have taken of the solar eclipse, into a movie representation of coronal evolution in time. This project will assimilate as much eclipse photography as possible from the public. The resulting movie(s) will cover all ranges of expertise, and at the basic smartphone or hand-held digital camera level, we expect to have obtained a huge number of images in the case of good weather conditions. The capability of modern digital technology to handle such a data flow is new. The basic purpose of this and the 2017 Megamovie observations is to explore this capability and its ability to engage people from many different communities in the solar science, astronomy, mathematics, and technology. The movie in 2017, especially, may also have important science impact because of the uniqueness of the corona as seen under eclipse conditions. In this presentation we will describe our smartphone application development (see the "Transit of Venus" app for a role model here). We will also summarize data acquisition via both the app and more traditional web interfaces. Although for the Coral Sea eclipse event we don't expect to have a movie product by the time of the AGU, for the 2017 event we do intend to assemble the heterogenous data into beautiful movies within a short space of time after the eclipse. These movies may have relatively low resolution but would extend to the base of the corona. We encourage participation in the 2012 observations, noting that no total eclipse, prior to 2017, will occur in a region with good infrastructure

Preparing a Nation for the Eclipse of a Generation -

Science.gov (United States)

Speck, Angela; Habbal, Shadia; Tresch Fienberg, Richard; Kentrianakis, Michael; Fraknoi, Andrew; Nordgren, Tyler; Penn, Matthew; Pasachoff, Jay M.; Bakich, Michael; Winter, Henry; Gay, Pamela; Motta, Mario

2018-01-01

On August 21st 2017, there was a total solar eclipse visible from a vast swath of the US.In preparation for that event, the American Astronomical society created a taskforce charged with planning for the eclipse for the entire nation. The preparations included interfacing with the public, the media, non-profit organizations and governmental organizations. Preliminary data suggests that nearly 90% of American adults watched the eclipse either directly or via live streams. Moreover, there were no major problems associated with the event, in spite of valiant attempts from, e.g. imprope solar viewing materials. The eclipse offered opportunities for many scientific experiments within and ebyond astronomy. Here we present on the work of the taskforce, and the lessons learned as well as lesser known science experiments undertaken during the eclipse.

Total Eclipse of the Ballpark: Connecting Space and Sports

Science.gov (United States)

Wasser, Molly; Petro, Noah; Jones, Andrea; Bleacher, Lora; Keller, John; Wes Patterson, G.

2018-01-01

The anticipation and excitement surrounding the total solar eclipse of 2017 provided astronomy educators with an incredible platform to share space science with huge audiences. The Public Engagement Team for NASA’s Lunar Reconnaissance Orbiter (LRO) took advantage of this opportunity to share lunar science with the public by highlighting the often-overlooked central player in the eclipse – the Moon. As the sole planetary science representatives on NASA’s Science Mission Directorate eclipse leadership team, the LRO team had limited resources to conduct national public outreach. In order to increase our reach, we found success in partnerships.In early 2017, we began working with Minor League Baseball (MiLB) teams across the path of totality on August eclipse events. These partnerships proved fruitful for both parties. While MiLB is a national organization, each team is deeply rooted in its community. This proved essential as each of our four main MiLB partners handled event logistics, provided facilities, connected NASA Subject Matter Experts (SMEs) with local media, and drew in captive crowds. With this tactic, a handful of NASA representatives were able to reach nearly 30,000 people. In turn, LRO provided engaging educational content relevant to the context, SMEs to guide the eclipse viewing experience, eclipse glasses, and safety information. Our participation drew in an audience who would not typically attend baseball games while we were able to reach individuals who would not normally attend a science event. In addition, the eclipse inspired one team, the Salem-Keizer Volcanoes from Salem, OR, to make baseball history by holding the first ever eclipse delay in professional sports.In this talk, we will present on the benefits of the partnership, offer lessons learned, and suggest ways to get involved for the 2024 eclipse – and all the baseball seasons in between.

Hubble Space Telescope Ultraviolet Light Curves Reveal Interesting Properties of CC Sculptoris and RZ Leonis

Energy Technology Data Exchange (ETDEWEB)

Szkody, Paula; Mukadam, Anjum S. [Department of Astronomy, University of Washington, Box 351580, Seattle, WA 98195 (United States); Toloza, Odette; Gänsicke, Boris T.; Pala, Anna F. [Department of Physics, University of Warwick, Coventry CV4 7AL (United Kingdom); Dai, Zhibin [Yunnan Observatories, Chinese Academy of Sciences, 396 Yangfangwang, Guandu District, Kunming, 650216 (China); Waagen, Elizabeth O. [AAVSO, 48 Bay State Rd, Cambridge, MA 02138 (United States); Godon, Patrick; Sion, Edward M., E-mail: szkody@astro.washington.edu [Department of Astrophysics and Planetary Science, Villanova University, Villanova, PA 19085 (United States)

2017-03-01

Time-tag ultraviolet data obtained on the Hubble Space Telescope in 2013 reveal interesting variability related to the white dwarf spin in the two cataclysmic variables RZ Leo and CC Scl. RZ Leo shows a period at 220 s and its harmonic at 110 s, thus identifying it as a likely Intermediate Polar (IP). The spin signal is not visible in a short single night of ground-based data in 2016, but the shorter exposures in that data set indicate a possible partial eclipse. The much larger UV amplitude of the spin signal in the known IP CC Scl allows the spin of 389 s, previously only seen at outburst, to be visible at quiescence. Spectra created from the peaks and troughs of the spin times indicate a hotter temperature of several thousand degrees during the peak phases, with multiple components contributing to the UV light.

LIGHT CURVES OF CORE-COLLAPSE SUPERNOVAE WITH SUBSTANTIAL MASS LOSS USING THE NEW OPEN-SOURCE SUPERNOVA EXPLOSION CODE (SNEC)

International Nuclear Information System (INIS)

Morozova, Viktoriya; Renzo, Mathieu; Ott, Christian D.; Clausen, Drew; Couch, Sean M.; Ellis, Justin; Roberts, Luke F.; Piro, Anthony L.

2015-01-01

We present the SuperNova Explosion Code (SNEC), an open-source Lagrangian code for the hydrodynamics and equilibrium-diffusion radiation transport in the expanding envelopes of supernovae. Given a model of a progenitor star, an explosion energy, and an amount and distribution of radioactive nickel, SNEC generates the bolometric light curve, as well as the light curves in different broad bands assuming blackbody emission. As a first application of SNEC, we consider the explosions of a grid of 15 M ⊙ (at zero-age main sequence, ZAMS) stars whose hydrogen envelopes are stripped to different extents and at different points in their evolution. The resulting light curves exhibit plateaus with durations of ∼20–100 days if ≳1.5–2 M ⊙ of hydrogen-rich material is left and no plateau if less hydrogen-rich material is left. If these shorter plateau lengths are not seen for SNe IIP in nature, it suggests that, at least for ZAMS masses ≲20 M ⊙ , hydrogen mass loss occurs as an all or nothing process. This perhaps points to the important role binary interactions play in generating the observed mass-stripped supernovae (i.e., Type Ib/c events). These light curves are also unlike what is typically seen for SNe IIL, arguing that simply varying the amount of mass loss cannot explain these events. The most stripped models begin to show double-peaked light curves similar to what is often seen for SNe IIb, confirming previous work that these supernovae can come from progenitors that have a small amount of hydrogen and a radius of ∼500 R ⊙