ORBITAL CIRCULARIZATION OF HOT AND COOL KEPLER ECLIPSING BINARIES

DOE Office of Scientific and Technical Information (OSTI.GOV)

Eylen, Vincent Van; Albrecht, Simon; Winn, Joshua N., E-mail: vincent@phys.au.dk

The rate of tidal circularization is predicted to be faster for relatively cool stars with convective outer layers, compared to hotter stars with radiative outer layers. Observing this effect is challenging because it requires large and well-characterized samples that include both hot and cool stars. Here we seek evidence of the predicted dependence of circularization upon stellar type, using a sample of 945 eclipsing binaries observed by Kepler . This sample complements earlier studies of this effect, which employed smaller samples of better-characterized stars. For each Kepler binary we measure e cos ω based on the relative timing of themore » primary and secondary eclipses. We examine the distribution of e cos ω as a function of period for binaries composed of hot stars, cool stars, and mixtures of the two types. At the shortest periods, hot–hot binaries are most likely to be eccentric; for periods shorter than four days, significant eccentricities occur frequently for hot–hot binaries, but not for hot–cool or cool–cool binaries. This is in qualitative agreement with theoretical expectations based on the slower dissipation rates of hot stars. However, the interpretation of our results is complicated by the largely unknown ages and evolutionary states of the stars in our sample.« less

Apsidal motion in eccentric eclipsing binaries: TV Ceti and V451 Ophiuchi

NASA Astrophysics Data System (ADS)

Wolf, M.; Diethelm, R.; Hornoch, K.

2001-07-01

Several new times of minimum light recorded with photoelectric means have been gathered for two bright eccentric eclipsing binaries TV Cet (P = 9fd1 , e = 0.055) and V451 Oph (P = 2fd2 , e = 0.013). Analysis of all available eclipse timings of TV Ceti has revealed a small motion of the line of apsides of dot ω = 0.000 30 +/- 0.000 08 deg cycle-1, corresponding to an apsidal period of U = 30 000 +/- 8 000 years. The contribution from the general relativity effects is dominant (dot ωrel/dot ω ~ 80 % ). In this system, the third body on an eccentric orbit with a period of 28.5 years is also predicted. The more precise values for the apsidal motion elements were computed for V451 Oph, where apsidal motion with a period of 170 +/- 5 years was confirmed. The corresponding internal structure constants log k2 were derived. Some of the observations reported in this paper were obtained at the South Africa Astronomical Observatory, Sutherland, South Africa.

Modeling the Effects of Asynchronous Rotation on Secondary Eclipse Timings in HW VIr Binaries

NASA Astrophysics Data System (ADS)

Clancy, Padraig

2018-01-01

HW Vir binaries are post common envelope binaries consisting of a hot subdwarf and red dwarf, with light curves dominated by primary eclipses, a strong reflection effect, and secondary eclipses. They have orbital periods ranging from a few hours to half a day and are generally thought to be tidally locked; most studies assume both synchronous rotation and zero eccentricity when modeling HW Vir light curves and radial velocities. Their stable eclipse timings are frequently used in O-C studies to look for the presence of circumbinary objects, measure evolutionary changes in the orbital period, and even constrain the component masses through Roemer delay measurements of the secondary eclipse. While most systems are probably tidally locked or close to it, even slightly asynchronous rotation could theoretically shift the orbital phase of the reflection effect. Here we investigate how asynchronous rotation might affect measurements of secondary eclipse timings by generating thousands of synthetic light curves with a range of reflection effect phases, fitting eclipse timings, and creating O-C diagrams.

DISCOVERY OF A RED GIANT WITH SOLAR-LIKE OSCILLATIONS IN AN ECLIPSING BINARY SYSTEM FROM KEPLER SPACE-BASED PHOTOMETRY

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hekker, S.; Debosscher, J.; De Ridder, J.

2010-04-20

Oscillating stars in binary systems are among the most interesting stellar laboratories, as these can provide information on the stellar parameters and stellar internal structures. Here we present a red giant with solar-like oscillations in an eclipsing binary observed with the NASA Kepler satellite. We compute stellar parameters of the red giant from spectra and the asteroseismic mass and radius from the oscillations. Although only one eclipse has been observed so far, we can already determine that the secondary is a main-sequence F star in an eccentric orbit with a semi-major axis larger than 0.5 AU and orbital period longermore » than 75 days.« less

Theoretical studies of binaries in astrophysics

NASA Astrophysics Data System (ADS)

Dischler, Johann Sebastian

This thesis introduces and summarizes four papers dealing with computer simulations of astrophysical processes involving binaries. The first part gives the rational and theoretical background to these papers. In paper I and II a statistical approach to studying eclipsing binaries is described. By using population synthesis models for binaries the probabilities for eclipses are calculated for different luminosity classes of binaries. These are compared with Hipparcos data and they agree well if one uses a standard input distribution for the orbit sizes. If one uses a random pairing model, where both companions are independently picked from an IMF, one finds too feclipsing binaries by an order of magnitude. In paper III we investigate a possible scenario for the origin of the stars observed close to the centre of our galaxy, called S stars. We propose that a cluster falls radially cowards the central black hole. The binaries within the cluster can then, if they have small impact parameters, be broken up by the black hole's tidal held and one of the components of the binary will be captured by the black hole. Paper IV investigates how the onset of mass transfer in eccentric binaries depends on the eccentricity. To do this we have developed a new two-phase SPH scheme where very light particles are at tire outer edge of our simulated star. This enables us to get a much better resolution of the very small mass that is transferred in close binaries. Our simulations show that the minimum required distance between the stars to have mass transfer decreases with the eccentricity.

Tidally Induced Pulsations in Kepler Eclipsing Binary KIC 3230227

NASA Astrophysics Data System (ADS)

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 M1 = 1.84 ± 0.18 M⊙, M2 = 1.73 ± 0.17 M⊙ and radii of R1 = 2.01 ± 0.09 R⊙, R2 = 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.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

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

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 amore » Herbig A0 star with disk-like emission lines, and Sh 2-252c is a pre-main-sequence star with very red color.« less

Short apsidal period of three eccentric eclipsing binaries discovered in the Large Magellanic Cloud

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hong, Kyeongsoo; Lee, Chung-Uk; Kim, Seung-Lee

2014-06-01

We present new elements of apsidal motion in three eccentric eclipsing binaries located in the Large Magellanic Cloud. The apsidal motions of the systems were analyzed using both light curves and eclipse timings. The OGLE-III data obtained during the long period of 8 yr (2002-2009) allowed us to determine the apsidal motion period from their analyses. The existence of third light in all selected systems was investigated by light curve analysis. The O – C diagrams of EROS 1018, EROS 1041, and EROS 1054 were analyzed using the 30, 44, and 26 new times of minimum light, respectively, determined frommore » full light curves constructed from EROS, MACHO, OGLE-II, OGLE-III, and our own observations. This enabled a detailed study of the apsidal motion in these systems for the first time. All of the systems have a significant apsidal motion below 100 yr. In particular, EROS 1018 shows a very fast apsidal period of 19.9 ± 2.2 yr in a detached system.« less

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gaulme, P.; McKeever, J.; Rawls, M. L.

2013-04-10

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 potentiallymore » 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 {delta}-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 candidate systems are encouraged. The resulting highly constrained stellar parameters will allow, for example, the exploration of how binary tidal interactions affect pulsations when compared to the single-star case.« less

Eclipsing binary stars as tests of gravity theories - The apsidal motion of AS Camelopardalis

NASA Technical Reports Server (NTRS)

Maloney, Frank P.; Guinan, Edward F.; Boyd, Patricia T.

1989-01-01

AS Camelopardalis is an 8th-magnitude eclipsing binary that consists of two main-sequence (B8 V and a B9.5 V) components in an eccentric orbit (e = 0.17) with an orbital period of 3.43 days. Like the eccentric eclipsing system DI Herculis, and a few other systems, AS Cam is an important test case for studying relativistic apsidal motion. In these systems, the theoretical general relativistic apsidal motion is comparable to that expected from classical effects arising from tidal and rotational deformation of the stellar components. Accurate determinations of the orbital and stellar properties of AS Cam have been made by Hilditch (1972) and Khalliulin and Kozyreva (1983) that permit the theoretical relativistic and classical contributions to the apsidal motion to be determined reasonably well. All the published timings of primary and secondary minima have been gathered and supplemented with eclipse timings from 1899 to 1920 obtained from the Harvard plate collection. Least-squares solutions of the eclipse timings extending over an 80 yr interval yield a smaller than expected apsidal motion, in agreement with that found by Khalliulin and Kozyreva from a smaller set of data. The observed apsidal motion for AS Cam is about one-third that expected from the combined relativistic and classical effects. Thus, AS Cam joins DI Her in having an observed apsidal motion significantly less than that predicted from theory.

Synthetic Survey of the Kepler Field

NASA Astrophysics Data System (ADS)

Wells, Mark; Prša, Andrej

2018-01-01

In the era of large scale surveys, including LSST and Gaia, binary population studies will flourish due to the large influx of data. In addition to probing binary populations as a function of galactic latitude, under-sampled groups such as low mass binaries will be observed at an unprecedented rate. To prepare for these missions, binary population simulations need to be carried out at high fidelity. These simulations will enable the creation of simulated data and, through comparison with real data, will allow the underlying binary parameter distributions to be explored. In order for the simulations to be considered robust, they should reproduce observed distributions accurately. To this end we have developed a simulator which takes input models and creates a synthetic population of eclipsing binaries. Starting from a galactic single star model, implemented using Galaxia, a code by Sharma et al. (2011), and applying observed multiplicity, mass-ratio, period, and eccentricity distributions, as reported by Raghavan et al. (2010), Duchêne & Kraus (2013), and Moe & Di Stefano (2017), we are able to generate synthetic binary surveys that correspond to any survey cadences. In order to calibrate our input models we compare the results of our synthesized eclipsing binary survey to the Kepler Eclipsing Binary catalog.

Tidal Synchronization and Differential Rotation of Kepler Eclipsing Binaries

NASA Astrophysics Data System (ADS)

Lurie, John C.; Vyhmeister, Karl; Hawley, Suzanne L.; Adilia, Jamel; Chen, Andrea; Davenport, James R. A.; Jurić, Mario; Puig-Holzman, Michael; Weisenburger, Kolby L.

2017-12-01

Few observational constraints exist for the tidal synchronization rate of late-type stars, despite its fundamental role in binary evolution. We visually inspected the light curves of 2278 eclipsing binaries (EBs) from the Kepler Eclipsing Binary Catalog to identify those with starspot modulations, as well as other types of out-of-eclipse variability. We report rotation periods for 816 EBs with starspot modulations, and find that 79% of EBs with orbital periods of less than 10 days are synchronized. However, a population of short-period EBs exists, with rotation periods typically 13% slower than synchronous, which we attribute to the differential rotation of high-latitude starspots. At 10 days, there is a transition from predominantly circular, synchronized EBs to predominantly eccentric, pseudosynchronized EBs. This transition period is in good agreement with the predicted and observed circularization period for Milky Way field binaries. At orbital periods greater than about 30 days, the amount of tidal synchronization decreases. We also report 12 previously unidentified candidate δ Scuti and γ Doradus pulsators, as well as a candidate RS CVn system with an evolved primary that exhibits starspot occultations. For short-period contact binaries, we observe a period-color relation and compare it to previous studies. As a whole, these results represent the largest homogeneous study of tidal synchronization of late-type stars.

APSIDAL MOTION AND A LIGHT CURVE SOLUTION FOR 13 LMC ECCENTRIC ECLIPSING BINARIES

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zasche, P.; Wolf, M.; Vraštil, J.

2015-12-15

New CCD observations for 13 eccentric eclipsing binaries from the Large Magellanic Cloud were carried out using the Danish 1.54 m telescope located at the La Silla Observatory in Chile. These systems were observed for their times of minimum and 56 new minima were obtained. These are needed for accurate determination of the apsidal motion. Besides that, in total 436 times of minimum were derived from the photometric databases OGLE and MACHO. The O – C diagrams of minimum timings for these B-type binaries were analyzed and the parameters of the apsidal motion were computed. The light curves of thesemore » systems were fitted using the program PHOEBE, giving the light curve parameters. We derived for the first time relatively short periods of the apsidal motion ranging from 21 to 107 years. The system OGLE-LMC-ECL-07902 was also analyzed using the spectra and radial velocities, resulting in masses of 6.8 and 4.4 M{sub ⊙} for the eclipsing components. For one system (OGLE-LMC-ECL-20112), the third-body hypothesis was also used to describe the residuals after subtraction of the apsidal motion, resulting in a period of about 22 years. For several systems an additional third light was also detected, which makes these systems suspect for triplicity.« less

V342 Andromedae B is an eccentric-orbit eclipsing binary

NASA Astrophysics Data System (ADS)

Dimitrov, W.; Kamiński, K.; Lehmann, H.; Ligęza, P.; Fagas, M.; Bagińska, P.; Kwiatkowski, T.; Bąkowska, K.; Kowalczyk, A.; Polińska, M.; Bartczak, P.; Przybyszewska, A.; Kruszewski, A.; Kurzawa, K.; Schwarzenberg-Czerny, A.

2015-03-01

We present a photometric and spectroscopic study of the visual binary V342 Andromedae. Visual components of the system have angular separations of 3 arcseconds. We obtained two spectroscopic data sets. An examination of both the A and B component spectra reveals that the B component is a spectroscopic binary with an eccentric orbit. The orbital period, taken from the Hipparcos Catalog, agrees with the orbital period of the B component measured spectroscopically. We also collected a new set of photometric measurements. The argument of periastron is close to 270° and the orbit eccentricity is not seen in our photometric data. About five years after the first spectroscopic observations, a new set of spectroscopic data was obtained. We analysed the apsidal motion, but we did not find any significant changes in the orbital orientation. A Wilson-Devinney model was calculated based on the photometric and the radial velocity curves. The result shows two very similar stars with masses M1 = 1.27 ± 0.01 M⊙, M2 = 1.28 ± 0.01 M⊙, respectively. The radii are R1 = 1.21 ± 0.01 R⊙, R2 = 1.25 ± 0.01 R⊙, respectively. Radial velocity measurements of component A, the most luminous star in the system, reveal no significant periodic variations. We calculated the time of the eclipsing binary orbit's circularization, which is about two orders of magnitude shorter than the estimated age of the system. The discrepancies in the age estimation can be explained by the Kozai effect induced by the visual component A. The atmospheric parameters and the chemical abundances for the eclipsing pair, as well as the LSD profiles for both visual components, were calculated from two high-resolution, well-exposed spectra obtained on the 2-m class telescope. Based on spectroscopy obtained at the David Dunlap Observatory, University of Toronto, Canada, Poznań Spectroscopic Telescope 1, Poland and Thüringer Landessternwarte, Tautenburg, Germany.

Two bodies with high eccentricity around the cataclysmic variable QS Vir

NASA Astrophysics Data System (ADS)

Almeida, Leonardo A.; Jablonski, Francisco

2011-11-01

QS Vir is an eclipsing cataclysmic variable with 3.618 hrs orbital period. This system has the interesting characteristics that it does not show mass transfer between the components through the L1 Lagrangian point and shows a complex orbital period variation history. Qian et al. (2010) associated the orbital period variations to the presence of a giant planet in the system plus angular momentum loss via magnetic braking. Parsons et al. (2010) obtained new eclipse timings and observed that the orbital period variations associated to a hypothetical giant planet disagree with their measurements and concluded that the decrease in orbital period is part of a cyclic variation with period ~16 yrs. In this work, we present 28 new eclipse timings of QS Vir and suggest that the orbital period variations can be explained by a model with two circumbinary bodies. The best fitting gives the lower limit to the masses M1 sin(i) ~ 0.0086 M⊙ and M2 sin(i) ~ 0.054 M⊙ orbital periods P1 ~ 14.4 yrs and P2 ~ 16.99 yrs, and eccentricities e1 ~ 0.62 and e2~0.92 for the two external bodies. Under the assumption of coplanarity among the two external bodies and the inner binary, we obtain a giant planet with ~0.009 M⊙ and a brown dwarf with ~ 0.056 M⊙ around the eclipsing binary QS Vir.

The O-type eclipsing contact binary LY Aurigae - member of a quadruple system

NASA Astrophysics Data System (ADS)

Mayer, Pavel; Drechsel, Horst; Harmanec, Petr; Yang, Stephenson; Šlechta, Miroslav

2013-11-01

The eclipsing binary LY Aur (O9 II + O9 III) belongs to the rare class of early-type contact systems. We obtained 23 new spectra at the Ondřejov and Dominion Astrophysical Observatories, which were analysed with four older Calar Alto and one ELODIE archive spectra. A new result of this study is that the visual companion of LY Aur - the spectral lines of which are clearly seen in our spectra - is also an SB1 binary having an orbital period of 20.46d, an eccentric orbit, and a radial velocity semi-amplitude of 33 km s-1. The Hα line blend contains an emission component, which shows dependence on the orbital phase of the eclipsing system, with the strongest emission around the secondary eclipse. Revised elements of the eclipsing binary and the orbital solution of the companion binary are determined from our set of spectra and new light-curve solutions of the eclipsing pair. The mass of the primary of 25.5 M⊙ agrees well with its spectral type, whereas the secondary mass of 14 M⊙ is smaller than expected. From an O-C analysis of the minimum times of LY Aur that span more than 40 years, we found that the orbital period is decreasing, indicating the presence of interaction processes. The system is likely in a phase of non-conservative mass exchange. Based on spectral observations collected at the German-Spanish Observatory, Calar Alto, Spain; Dominion Astrophysical Observatory, Canada; Ondřejov Observatory, Czech Republic, and an archival Haute Provence Observatory ELODIE spectrum.

Survival of planets around shrinking stellar binaries

PubMed Central

Muñoz, Diego J.; Lai, Dong

2015-01-01

The discovery of transiting circumbinary planets by the Kepler mission suggests that planets can form efficiently around binary stars. None of the stellar binaries currently known to host planets has a period shorter than 7 d, despite the large number of eclipsing binaries found in the Kepler target list with periods shorter than a few days. These compact binaries are believed to have evolved from wider orbits into their current configurations via the so-called Lidov–Kozai migration mechanism, in which gravitational perturbations from a distant tertiary companion induce large-amplitude eccentricity oscillations in the binary, followed by orbital decay and circularization due to tidal dissipation in the stars. Here we explore the orbital evolution of planets around binaries undergoing orbital decay by this mechanism. We show that planets may survive and become misaligned from their host binary, or may develop erratic behavior in eccentricity, resulting in their consumption by the stars or ejection from the system as the binary decays. Our results suggest that circumbinary planets around compact binaries could still exist, and we offer predictions as to what their orbital configurations should be like. PMID:26159412

Survival of planets around shrinking stellar binaries.

PubMed

Muñoz, Diego J; Lai, Dong

2015-07-28

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

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

NASA Astrophysics Data System (ADS)

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.

Further Evidence of a Brown Dwarf Orbiting the Post-Common Envelope Eclipsing Binary V470 Cam (HS 0705+6700)

NASA Astrophysics Data System (ADS)

Bogensberger, David; Clarke, Fraser; Lynas-Gray, Anthony Eugene

2017-12-01

Several post-common envelope binaries have slightly increasing, decreasing or oscillating orbital periods. One of several possible explanations is light travel-time changes, caused by the binary centre-of-mass being perturbed by the gravitational pull of a third body. Further studies are necessary because it is not clear how a third body could have survived subdwarf progenitor mass-loss at the tip of the Red Giant Branch, or formed subsequently. Thirty-nine primary eclipse times for V470 Cam were secured with the Philip Wetton Telescope during the period 2016 November 25th to 2017 January 27th. Available eclipse timings suggest a brown dwarf tertiary having a mass of at least 0.0236(40) M⊙, an elliptical orbit with an eccentricity of 0.376(98) and an orbital period of 11.77(67) years about the binary centreof- mass. The mass and orbit suggest a hybrid formation, in which some ejected material from the subdwarf progenitor was accreted on to a precursor tertiary component, although additional observations would be needed to confirm this interpretation and investigate other possible origins for the binary orbital period change.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Prša, A.; Conroy, K. E.; Horvat, M.

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 weremore » 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.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Barlow, Brad N.; Wade, Richard A.; Liss, Sandra E.

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 averagemore » 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}.« less

Absolute Properties of the Eclipsing Binary Star BF Draconis

NASA Astrophysics Data System (ADS)

Lacy, Claud H. Sandberg; Torres, Guillermo; Fekel, Francis C.; Sabby, Jeffrey A.; Claret, Antonio

2012-06-01

BF Dra is now known to be an eccentric double-lined F6+F6 binary star with relatively deep (0.7 mag) partial eclipses. Previous studies of the system are improved with 7494 differential photometric observations from the URSA WebScope and 9700 from the NFO WebScope, 106 high-resolution spectroscopic observations from the Tennessee State University 2 m automatic spectroscopic telescope and the 1 m coudé-feed spectrometer at Kitt Peak National Observatory, and 31 accurate radial velocities from the CfA. Very accurate (better than 0.6%) masses and radii are determined from analysis of the two new light curves and four radial velocity curves. Theoretical models match the absolute properties of the stars at an age of about 2.72 Gyr and [Fe/H] = -0.17, and tidal theory correctly confirms that the orbit should still be eccentric. Our observations of BF Dra constrain the convective core overshooting parameter to be larger than about 0.13 Hp . We find, however, that standard tidal theory is unable to match the observed slow rotation rates of the components' surface layers.

The Three-body System δ Circini

NASA Astrophysics Data System (ADS)

Mayer, Pavel; Harmanec, Petr; Sana, Hugues; Le Bouquin, Jean-Baptiste

2014-12-01

Delta Cir is known as an O7.5 III eclipsing and spectroscopic binary with an eccentric orbit. Penny et al. discovered the presence of a third component in the IUE spectra. The eclipsing binary and the third body revolve around a common center of gravity with a period of 1644 days in an eccentric orbit with a semimajor axis of 10 AU. We demonstrate the presence of apsidal-line rotation with a period of ≈141 yr, which is considerably longer than its theoretically predicted value, based on the published radii of the binary components derived from the Hipparchos H p light curve. However, our new solution of the same light curve resulted in smaller radii and better agreement between the observed and predicted period of the apsidal-line advance. There are indications that the third body is a binary. The object was resolved by VLTI using the PIONIER combiner; in 2012 June, the separation was 3.78 mas with magnitude difference in the H region 1.ͫ75. This result means that (assuming a distance of 770 pc) the inclination of the long orbit is 87.°7. Based on data products from observations made with ESO Telescopes at the La Silla Paranal Observatory under programs ID 65.N-0577, 67.B-0504, 074D-0300, 178.D-0361, 182.D-0356, 083.D-0589, 185.D-0056, 086.D-0997, and 087D-0946.

KIC 11401845: An Eclipsing Binary with Multiperiodic Pulsations and Light-travel Time

NASA Astrophysics Data System (ADS)

Lee, Jae Woo; Hong, Kyeongsoo; Kim, Seung-Lee; Koo, Jae-Rim

2017-02-01

We report the {\\text{}}{Kepler} photometry of KIC 11401845 displaying multiperiodic pulsations, superimposed on binary effects. Light-curve synthesis shows that the binary star is a short-period detached system with a very low mass ratio of q = 0.070 and filling factors of F1 = 45% and F2 = 99%. Multiple-frequency analyses were applied to the light residuals after subtracting the synthetic eclipsing curve from the observed data. We detected 23 frequencies with signal-to-noise ratios larger than 4.0, of which the orbital harmonics (f4, f6, f9, f15) in the low-frequency domain may originate from tidally excited modes. For the high frequencies of 13.7-23.8 day-1, the period ratios and pulsation constants are in the ranges of {P}{pul}/{P}{orb}=0.020{--}0.034 and Q = 0.018-0.031 days, respectively. These values and the position on the Hertzsprung-Russell diagram demonstrate that the primary component is a δ Sct pulsating star. We examined the eclipse timing variation of KIC 11401845 from the pulsation-subtracted data and found a delay of 56 ± 17 s in the arrival times of the secondary eclipses relative to the primary eclipses. A possible explanation of the time shift may be some combination of a light-travel-time delay of about 34 s and a very small eccentricity of e\\cos ω < 0.0002. This result represents the first measurement of the Rømer delay in noncompact binaries.

HEARTBEAT STARS: SPECTROSCOPIC ORBITAL SOLUTIONS FOR SIX ECCENTRIC BINARY SYSTEMS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Smullen, Rachel A.; Kobulnicky, Henry A., E-mail: rsmullen@email.arizona.edu

2015-08-01

We present multi-epoch spectroscopy of “heartbeat stars,” eccentric binaries with dynamic tidal distortions and tidally induced pulsations originally discovered with the Kepler satellite. Optical spectra of six known heartbeat stars using the Wyoming Infrared Observatory 2.3 m telescope allow measurement of stellar effective temperatures and radial velocities from which we determine orbital parameters including the periods, eccentricities, approximate mass ratios, and component masses. These spectroscopic solutions confirm that the stars are members of eccentric binary systems with eccentricities e > 0.34 and periods P = 7–20 days, strengthening conclusions from prior works that utilized purely photometric methods. Heartbeat stars inmore » this sample have A- or F-type primary components. Constraints on orbital inclinations indicate that four of the six systems have minimum mass ratios q = 0.3–0.5, implying that most secondaries are probable M dwarfs or earlier. One system is an eclipsing, double-lined spectroscopic binary with roughly equal-mass mid-A components (q = 0.95), while another shows double-lined behavior only near periastron, indicating that the F0V primary has a G1V secondary (q = 0.65). This work constitutes the first measurements of the masses of secondaries in a statistical sample of heartbeat stars. The good agreement between our spectroscopic orbital elements and those derived using a photometric model support the idea that photometric data are sufficient to derive reliable orbital parameters for heartbeat stars.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kostov, Veselin B.; Orosz, Jerome A.; Welsh, William F.

We report the discovery of a new Kepler transiting circumbinary planet (CBP). This latest addition to the still-small family of CBPs defies the current trend of known short-period planets orbiting near the stability limit of binary stars. Unlike the previous discoveries, the planet revolving around the eclipsing binary system Kepler-1647 has a very long orbital period (∼1100 days) and was at conjunction only twice during the Kepler mission lifetime. Due to the singular configuration of the system, Kepler-1647b is not only the longest-period transiting CBP at the time of writing, but also one of the longest-period transiting planets. With amore » radius of 1.06 ± 0.01 R {sub Jup}, it is also the largest CBP to date. The planet produced three transits in the light curve of Kepler-1647 (one of them during an eclipse, creating a syzygy) and measurably perturbed the times of the stellar eclipses, allowing us to measure its mass, 1.52 ± 0.65 M {sub Jup}. The planet revolves around an 11-day period eclipsing binary consisting of two solar-mass stars on a slightly inclined, mildly eccentric ( e {sub bin} = 0.16), spin-synchronized orbit. Despite having an orbital period three times longer than Earth’s, Kepler-1647b is in the conservative habitable zone of the binary star throughout its orbit.« less

Kepler-1647b: The Largest and Longest-period Kepler Transiting Circumbinary Planet

NASA Astrophysics Data System (ADS)

Kostov, Veselin B.; Orosz, Jerome A.; Welsh, William F.; Doyle, Laurance R.; Fabrycky, Daniel C.; Haghighipour, Nader; Quarles, Billy; Short, Donald R.; Cochran, William D.; Endl, Michael; Ford, Eric B.; Gregorio, Joao; Hinse, Tobias C.; Isaacson, Howard; Jenkins, Jon M.; Jensen, Eric L. N.; Kane, Stephen; Kull, Ilya; Latham, David W.; Lissauer, Jack J.; Marcy, Geoffrey W.; Mazeh, Tsevi; Müller, Tobias W. A.; Pepper, Joshua; Quinn, Samuel N.; Ragozzine, Darin; Shporer, Avi; Steffen, Jason H.; Torres, Guillermo; Windmiller, Gur; Borucki, William J.

2016-08-01

We report the discovery of a new Kepler transiting circumbinary planet (CBP). This latest addition to the still-small family of CBPs defies the current trend of known short-period planets orbiting near the stability limit of binary stars. Unlike the previous discoveries, the planet revolving around the eclipsing binary system Kepler-1647 has a very long orbital period (˜1100 days) and was at conjunction only twice during the Kepler mission lifetime. Due to the singular configuration of the system, Kepler-1647b is not only the longest-period transiting CBP at the time of writing, but also one of the longest-period transiting planets. With a radius of 1.06 ± 0.01 R Jup, it is also the largest CBP to date. The planet produced three transits in the light curve of Kepler-1647 (one of them during an eclipse, creating a syzygy) and measurably perturbed the times of the stellar eclipses, allowing us to measure its mass, 1.52 ± 0.65 M Jup. The planet revolves around an 11-day period eclipsing binary consisting of two solar-mass stars on a slightly inclined, mildly eccentric (e bin = 0.16), spin-synchronized orbit. Despite having an orbital period three times longer than Earth’s, Kepler-1647b is in the conservative habitable zone of the binary star throughout its orbit.

The SUrvey for Pulsars and Extragalactic Radio Bursts - I. Survey description and overview

NASA Astrophysics Data System (ADS)

Keane, E. F.; Barr, E. D.; Jameson, A.; Morello, V.; Caleb, M.; Bhandari, S.; Petroff, E.; Possenti, A.; Burgay, M.; Tiburzi, C.; Bailes, M.; Bhat, N. D. R.; Burke-Spolaor, S.; Eatough, R. P.; Flynn, C.; Jankowski, F.; Johnston, S.; Kramer, M.; Levin, L.; Ng, C.; van Straten, W.; Krishnan, V. Venkatraman

2018-01-01

We describe the Survey for Pulsars and Extragalactic Radio Bursts (SUPERB), an ongoing pulsar and fast transient survey using the Parkes radio telescope. SUPERB involves real-time acceleration searches for pulsars and single-pulse searches for pulsars and fast radio bursts. We report on the observational set-up, data analysis, multiwavelength/messenger connections, survey sensitivities to pulsars and fast radio bursts and the impact of radio frequency interference. We further report on the first 10 pulsars discovered in the project. Among these is PSR J1306-40, a millisecond pulsar in a binary system where it appears to be eclipsed for a large fraction of the orbit. PSR J1421-4407 is another binary millisecond pulsar; its orbital period is 30.7 d. This orbital period is in a range where only highly eccentric binaries are known, and expected by theory; despite this its orbit has an eccentricity of 10-5.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, Chien-Hsiu, E-mail: leech@naoj.org

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 determinemore » 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.« less

Decoding of the light changes in eclipsing Wolf-Rayet binaries. I. A non-classical approach to the solution of light curves

NASA Astrophysics Data System (ADS)

Perrier, C.; Breysacher, J.; Rauw, G.

2009-09-01

Aims: We present a technique to determine the orbital and physical parameters of eclipsing eccentric Wolf-Rayet + O-star binaries, where one eclipse is produced by the absorption of the O-star light by the stellar wind of the W-R star. Methods: Our method is based on the use of the empirical moments of the light curve that are integral transforms evaluated from the observed light curves. The optical depth along the line of sight and the limb darkening of the W-R star are modelled by simple mathematical functions, and we derive analytical expressions for the moments of the light curve as a function of the orbital parameters and the key parameters of the transparency and limb-darkening functions. These analytical expressions are then inverted in order to derive the values of the orbital inclination, the stellar radii, the fractional luminosities, and the parameters of the wind transparency and limb-darkening laws. Results: The method is applied to the SMC W-R eclipsing binary HD 5980, a remarkable object that underwent an LBV-like event in August 1994. The analysis refers to the pre-outburst observational data. A synthetic light curve based on the elements derived for the system allows a quality assessment of the results obtained.

Distance Estimation for Eclipsing X-Ray Pulsars

NASA Astrophysics Data System (ADS)

Wilson, Robert E.; Paul, B.; Raichur, H.

2006-06-01

Recent interest in eclipsing binaries as distance indicators leads naturally into direct distance estimation for X-ray pulsars by combination of pulse arrival times, radial velocities, X-ray eclipse duration, and spectra. Optical light curves may help in some cases by measuring tides and irradiation, although dynamical tides in eccentric systems limit light curve usefulness. Pulse arrivals give an absolute scale and also orbit shape and orientation, which may be poorly known from radial velocities. For example, orbital eccentricity of 0.09 is known from Vela X1 pulse arrivals, although optical velocities are too noisy to measure eccentricity accurately. Combined pulse and optical velocity data give mass information. A lower limit to sin i from eclipse duration sets a lower limit to R2, and for the general eccentric case. A mass ratio sets lobe size and thus an upper limit to R2, so boxing R2 within a narrow range may be possible. T2 can be assessed from spectra so EB distance estimation can work if magnitude is known in one or more standard bands such as B or V. Realistic distance uncertainties are explored. In regard to new observations, Vela X-1 was observed by RXTE over about nine days in January 2005, including an eclipse of about 3.5 days. We extracted the light curves with time resolution 0.125 s. Spin period measurements by the Chi square criterion show Doppler variation with orbital phase and mean spin period 283.5 s. Pulse profiles of that period were averaged in sets of 10 at 138 phases. Cross correlation for the first 40 pulses show the expected Doppler arrival time variation. As the Vela X-1 pulse period is large compared to light travel time across the orbit, the pulses are already phase connected. Support is by U.S. National Science Foundation grant 0307561.

The Quadruple-lined, Doubly Eclipsing System V482 Persei

NASA Astrophysics Data System (ADS)

Torres, Guillermo; Sandberg Lacy, Claud H.; Fekel, Francis C.; Wolf, Marek; Muterspaugh, Matthew W.

2017-09-01

We report spectroscopic and differential photometric observations of the A-type system V482 Per, which reveal it to be a rare hierarchical quadruple system containing two eclipsing binaries. One binary has the previously known orbital period of 2.4 days and a circular orbit, and the other a period of 6 days, a slightly eccentric orbit (e = 0.11), and shallow eclipses only 2.3% deep. The two binaries revolve around their common center of mass in a highly elongated orbit (e = 0.85) with a period of 16.67 yr. Radial velocities are measured for all components from our quadruple-lined spectra and are combined with the light curves and measurements of times of minimum light for the 2.4 day binary to solve for the elements of the inner and outer orbits simultaneously. The line-of-sight inclination angles of the three orbits are similar, suggesting they may be close to coplanar. The available observations appear to indicate that the 6 day binary experiences significant retrograde apsidal motion in the amount of about 60 deg per century. We derive absolute masses for the four stars good to better than 1.5%, along with radii with formal errors of 1.1% and 3.5% for the 2.4 day binary and ˜9% for the 6 day binary. A comparison of these and other physical properties with current stellar evolution models gives excellent agreement for a metallicity of [{Fe}/{{H}}]=-0.15 and an age of 360 Myr.

The binary Kuiper-belt object 1998 WW31.

PubMed

Veillet, Christian; Parker, Joel Wm; Griffin, Ian; Marsden, Brian; Doressoundiram, Alain; Buie, Marc; Tholen, David J; Connelley, Michael; Holman, Matthew J

2002-04-18

The recent discovery of a binary asteroid during a spacecraft fly-by generated keen interest, because the orbital parameters of binaries can provide measures of the masses, and mutual eclipses could allow us to determine individual sizes and bulk densities. Several binary near-Earth, main-belt and Trojan asteroids have subsequently been discovered. The Kuiper belt-the region of space extending from Neptune (at 30 astronomical units) to well over 100 AU and believed to be the source of new short-period comets-has become a fascinating new window onto the formation of our Solar System since the first member object, not counting Pluto, was discovered in 1992 (ref. 13). Here we report that the Kuiper-belt object 1998 WW31 is binary with a highly eccentric orbit (eccentricity e approximately 0.8) and a long period (about 570 days), very different from the Pluto/Charon system, which was hitherto the only previously known binary in the Kuiper belt. Assuming a density in the range of 1 to 2 g cm-3, the albedo of the binary components is between 0.05 and 0.08, close to the value of 0.04 generally assumed for Kuiper-belt objects.

Absolute Properties of the Low-Mass Eclipsing Binary CM Draconis

NASA Astrophysics Data System (ADS)

Morales, Juan Carlos; Ribas, Ignasi; Jordi, Carme; Torres, Guillermo; Gallardo, José; Guinan, Edward F.; Charbonneau, David; Wolf, Marek; Latham, David W.; Anglada-Escudé, Guillem; Bradstreet, David H.; Everett, Mark E.; O'Donovan, Francis T.; Mandushev, Georgi; Mathieu, Robert D.

2009-02-01

Spectroscopic and eclipsing binary systems offer the best means for determining accurate physical properties of stars, including their masses and radii. The data available for low-mass stars have yielded firm evidence that stellar structure models predict smaller radii and higher effective temperatures than observed, but the number of systems with detailed analyses is still small. In this paper, we present a complete reanalysis of one of such eclipsing systems, CM Dra, composed of two dM4.5 stars. New and existing light curves as well as a radial velocity curve are modeled to measure the physical properties of both components. The masses and radii determined for the components of CM Dra are M 1 = 0.2310 ± 0.0009 M sun, M 2 = 0.2141 ± 0.0010M sun, R 1 = 0.2534 ± 0.0019 R sun, and R 2 = 0.2396 ± 0.0015 R sun. With relative uncertainties well below the 1% level, these values constitute the most accurate properties to date for fully convective stars. This makes CM Dra a valuable benchmark for testing theoretical models. In comparing our measurements with theory, we confirm the discrepancies previously reported for other low-mass eclipsing binaries. These discrepancies seem likely to be due to the effects of magnetic activity. We find that the orbit of this system is slightly eccentric, and we have made use of eclipse timings spanning three decades to infer the apsidal motion and other related properties.

Eclipsing Binaries with Possible Tertiary Components

NASA Astrophysics Data System (ADS)

Snyder, LeRoy F.

2013-05-01

Many eclipsing binary star systems (EBS) show long-term variations in their orbital periods which are evident in their O-C (observed minus calculated period) diagrams. This research carried out an analysis of 324 eclipsing binary systems taken from the systems analyzed in the Bob Nelson's O-C Files database. Of these 18 systems displayed evidence of periodic variations of the arrival times of the eclipses. These rates of period changes are sinusoidal variations. The sinusoidal character of these variations is suggestive of Keplerian motion caused by an orbiting companion. The reason for these changes is unknown, but mass loss, apsidal motion, magnetic activity and the presence of a third body have been proposed. This paper has assumed light time effect as the cause of the sinusoidal variations caused by the gravitational pull of a tertiary companion orbiting around the eclipsing binary systems. An observed minus calculated (O-C) diagram of the 324 systems was plotted using a quadratic ephemeris to determine if the system displayed a sinusoidal trend in theO-C residuals. After analysis of the 18 systems, seven systems, AW UMa, BB PEG, OO Aql, V508 Oph, VW Cep, WCrv and YY ERI met the benchmark of the criteria of a possible orbiting companion. The other 11 systems displayed a sinusoidal variation in the O-C residuals of the primary eclipses but these systems in the Bob Nelson's O-C Files did not contain times of minimum (Tmin) of the secondary eclipses and therefore not conclusive in determining the presents of the effects of a tertiary companion. An analysis of the residuals of the seven systems yields a light-time semi-amplitude, orbital period, eccentricity and mass of the tertiary companion as the amplitude of the variation is proportional to the mass, period and inclination of the 3rd orbiting body. Knowing the low mass of the tertiary body in the seven cases the possibility of five of these tertiary companions being brown dwarfs is discussed.

The Effects of Barycentric and Asymmetric Transverse Velocities on Eclipse and Transit Times

NASA Astrophysics Data System (ADS)

Conroy, Kyle E.; Prša, Andrej; Horvat, Martin; Stassun, Keivan G.

2018-02-01

It has long been recognized that the finite speed of light can affect the observed time of an event. For example, as a source moves radially toward or away from an observer, the path length and therefore the light travel time to the observer decreases or increases, causing the event to appear earlier or later than otherwise expected, respectively. This light travel time effect has been applied to transits and eclipses for a variety of purposes, including studies of eclipse timing variations and transit timing variations that reveal the presence of additional bodies in the system. Here we highlight another non-relativistic effect on eclipse or transit times arising from the finite speed of light—caused by an asymmetry in the transverse velocity of the two eclipsing objects, relative to the observer. This asymmetry can be due to a non-unity mass ratio or to the presence of external barycentric motion. Although usually constant, this barycentric and asymmetric transverse velocity (BATV) effect can vary between sequential eclipses if either the path length between the two objects or the barycentric transverse velocity varies in time. We discuss this BATV effect and estimate its magnitude for both time-dependent and time-independent cases. For the time-dependent cases, we consider binaries that experience a change in orbital inclination, eccentric systems with and without apsidal motion, and hierarchical triple systems. We also consider the time-independent case which, by affecting the primary and secondary eclipses differently, can influence the inferred system parameters, such as the orbital eccentricity.

Monitoring HD 148703 during upcoming eclipses

NASA Astrophysics Data System (ADS)

Waagen, Elizabeth O.

2017-06-01

Dr. Milena Ratajczak (University of Wrocław) has requested AAVSO observers' assistance in monitoring the very bright (V = 4.23) and very unusual eclipsing binary HD 148703 (HR 6143, N Sco) during its infrequent primary and secondary eclipses scheduled for 2017 June 11 and June 14, respectively. Dr. Ratajczak writes: "[HD 148703] N Sco is a B-type detached eclipsing binary, which turned out to be an exceptionally interesting object to study when we realised its orbital period is 223 days and time between eclipses is only 3.5 days. Such configuration makes it an extremely eccentric system, probably the most eccentric from any objects of that class ever studied...Since the object is very bright, it's difficult to use professional photometric telescopes due to saturation issues. That is why we kindly invite amateur astronomers to join the campaign. Data taken during times of eclipses (photometry) and time between eclipses (radial velocities from spectroscopy) which occur next week are crucial to cover in order to determine orbital and stellar parameters of system's components. Data taken over that time will be of very high value for us." The next primary eclipse time of minimum is on 2017 June 11 (UT 00:41:45), and the secondary on June 14 (UT 09:17:34). Each eclipse lasts about 20 hours. The amplitude of the primary eclipse is 0.15 magnitude, and the secondary 0.35 mag. PEP V and DSLR V photometry is requested. (CCD V is welcome if saturation can be avoided.) Beginning immediately, one to a few snapshots each night are requested to establish an out-of-eclipse baseline for each observer; they should continue for a few nights after the secondary eclipse has occurred.Time series photometry is requested beginning 12 hours before each time of minimum and continuing until 12 hours after. Precision to 0.01 mag or better per single observation is needed. Exposures should be as long as possible without saturating; don't make very short exposures simply for the purpose of gathering more data points. B or Ic data would also be useful; B is preferred to Ic. If imaging in more than one filter, please make five V observations for each B or Ic.Visual observations are also welcome. For spectroscopy now through June 20, resolution of at least a few thousands is needed. Coordinates: RA = 16 31 22.93 Dec = -34 42 15.7 (2000.0). Finder charts may be created and data from the AAVSO International Database may be viewed, plotted, or downloaded (www.aavso.org).

Formation of a 'planet' by rapid evaporation of a pulsar's companion

NASA Technical Reports Server (NTRS)

Rasio, F. A.; Shapiro, S. L.; Teukolsky, S. A.

1992-01-01

A model based on the binary configuration of the PSR1829-10 pulsar (Bailes et al., 1991) is used to show that the formation of a binary pulsar with a planet-size companion, large original separation, and small eccentricity could result from the rapid evaporation of a much more massive binary companion by the pulsar's radiation. Such an evaporation process is known to be taking place in at least two other binary pulsars: PSR1957 + 20 (Fruchter et al., 1990; Ryba and Taylor, 1991) and PSR1744 - 24A (Lyne et al., 1990). It is shown here that, about one million years ago, the companion mass and binary separation could have been comparable to those currently observed in the eclipsing binary pulsar PSR1957 + 20.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lacy, C.H.; Frueh, M.L.

1985-08-01

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, andmore » 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.« less

Structure in the Disk of epsilon Aurigae - Analysis of ARCES and TripleSpec spectra from the 2010 eclipse

NASA Astrophysics Data System (ADS)

Gibson, Justus L.; Stencel, Robert E.; Ketzeback, William; Barentine, John; Coughlin, Jeffrey; Leadbeater, Robin; Saurage, Gabrelle

2018-06-01

Worldwide interest in the recent eclipse of epsilon Aurigae resulted in the generation of several extensive data sets, including high resolution spectroscopic monitoring. This lead to the discovery, among other things, of the existence of a mass transfer stream, seen notably during third contact. We explored spectroscopic facets of the mass transfer stream during third contact, using high resolution spectra obtained with the ARCES and TripleSpec instruments at Apache Point Observatory. One hundred and sixteen epochs of data were obtained between 2009 and 2012, and equivalent widths and line velocities measured for high versus low eccentricity accretion disk lines. These datasets also enable greater detail to be measured of the mid-eclipse enhancement of the He I 10830Å line, and the discovery of the P Cygni shape of the Pa-β line at third contact. We found evidence of higher speed material, associated with the mass transfer stream, persisting between third and fourth eclipse contacts. We visualized the disk and stream interaction using SHAPE software, and used CLOUDY software to estimate that the source of the enhanced He I 10830A absorption arises from a region with nH = 1011 cm-3 and temperature of 20,000 K, consistent with a mid-B type central star. Van Rensbergen binary star evolutionary models are somewhat consistent with the current binary parameters for their case of a 9 plus 8 solar mass initial binary, evolving into a 2.3 and 14.11 solar mass end product after 35 Myr. With these results, it is possible to make predictions which suggest that continued monitoring prior to the next eclipse (2036) will help resolve standing questions about the mass and age of this binary.

The physical properties and orbital parameters of the triple system V402 Lac

NASA Astrophysics Data System (ADS)

Hoyman, B.; Kalomeni, B.; Yakut, K.

2018-04-01

We present first ground-based multi-colors photometric study of an eccentric, double-lined eclipsing binary system V402 Lac. Analyzing the data obtained in this study together with earlier studies in the literature we derived the orbital and physical parameters of this detached binary system of considerable interest. Derived physical parameters of the components are as follows; M1 = 2.95 ± 0.06M⊙ , M2 = 2.86 ± 0.06M⊙ , R1 = 2.61 ± 0.04R⊙ , R2 = 2.16 ± 0.03R⊙ , L1 = 98 ± 5L⊙ and L2 = 69 ± 3L⊙ . Using the newly obtained parameters the distance of the binary is determined to be 262 ± 33 pc. In addition, the system show apsidal motion whose period is determined to be 213 years. A possible third star (M3 sin i = 1.9M⊙) orbiting the binary system in an eccentric orbit (e = 0.23) with an orbital period of 20.5 years has been detected in this study with LTT.

BRITE-Constellation reveals evidence for pulsations in the enigmatic binary η Carinae

NASA Astrophysics Data System (ADS)

Richardson, Noel D.; Pablo, Herbert; Sterken, Christiaan; Pigulski, Andrzej; Koenigsberger, Gloria; Moffat, Anthony F. J.; Madura, Thomas I.; Hamaguchi, Kenji; Corcoran, Michael F.; Damineli, Augusto; Gull, Theodore R.; Hillier, D. John; Weigelt, Gerd; Handler, Gerald; Popowicz, Adam; Wade, Gregg A.; Weiss, Werner W.; Zwintz, Konstanze

2018-04-01

η Car is a massive, eccentric binary with a rich observational history. We obtained the first high-cadence, high-precision light curves with the BRITE-Constellation nanosatellites over 6 months in 2016 and 6 months in 2017. The light curve is contaminated by several sources including the Homunculus nebula and neighbouring stars, including the eclipsing binary CPD -59°2628. However, we found two coherent oscillations in the light curve. These may represent pulsations that are not yet understood but we postulate that they are related to tidally excited oscillations of η Car's primary star, and would be similar to those detected in lower mass eccentric binaries. In particular, one frequency was previously detected by van Genderen et al. and Sterken et al. through the time period of 1974-1995 through timing measurements of photometric maxima. Thus, this frequency seems to have been detected for nearly four decades, indicating that it has been stable in frequency over this time span. These pulsations could help provide the first direct constraints on the fundamental parameters of the primary star if confirmed and refined with future observations.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Guo, Zhao; Gies, Douglas R.; Fuller, Jim, E-mail: guo@astro.gsu.edu, E-mail: gies@chara.gsu.edu, E-mail: jfuller@caltech.edu

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.more » 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.« less

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Faigler, S.; Kull, I.; Mazeh, T.

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, andmore » 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.« less

Binary Model for the Heartbeat Star System KIC 4142768

NASA Astrophysics Data System (ADS)

Manuel, Joseph; Hambleton, Kelly

2018-01-01

Heartbeat stars are a class of eccentric (e > 0.2) binary systems that undergo strong tidal forces. These tidal forces cause the shape of each star and the temperature across the stellar surfaces to change. This effect also generates variations in the light curve in the form of tidally-induced pulsations, which are theorized to have a significant effect on the circularization of eccentric orbits (Zahn, 1975). Using the binary modeling software PHOEBE (Prša & Zwitter 2005) on the Kepler photometric data and Keck radial velocity data for the eclipsing, heartbeat star KIC 4142768, we have determined the fundamental parameters including masses and radii. The frequency analysis of the residual data has surprisingly revealed approximately 29 pulsations with 8 being Delta Scuti pulsations, 10 being Gamma Doradus pulsations, and 11 being tidally-induced pulsations. After subtracting an initial binary model from the original, detrended photometric data, we analyzed the pulsation frequencies in the residual data. We then were able to disentangle the identified pulsations from the original data in order to conduct subsequent binary modeling. We plan to continue this study by applying asteroseismology to KIC 4142768. Through our continued investigation, we hope to extract information about the star’s internal structure and expect this will yield additional, interesting results.

ABSOLUTE PROPERTIES OF THE HIGHLY ECCENTRIC, SOLAR-TYPE ECLIPSING BINARY HD 74057

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sowell, James R.; Henry, Gregory W.; Fekel, Francis C., E-mail: jim.sowell@physics.gatech.edu, E-mail: gregory.w.henry@gmail.com, E-mail: fekel@evans.tsuniv.edu

2012-01-15

We have obtained Stroemgren b and y differential photometric observations of the solar-type eclipsing binary HD 74057 plus follow-up high-resolution, red wavelength spectroscopic observations. The system has an orbital period of 31.2198 days, a high eccentricity of 0.47, and is seen almost exactly edge on with an inclination of 89.{sup 0}8. The two main-sequence G0 stars are nearly identical in all physical characteristics. We used the Wilson-Devinney program to obtain a simultaneous solution of our photometric and spectroscopic observations. The resulting masses of the components are M{sub 1} = 1.138 {+-} 0.003 M{sub Sun} and M{sub 2} = 1.131 {+-}more » 0.003 M{sub Sun }, and the radii are R{sub 1} = 1.064 {+-} 0.002 R{sub Sun} and R{sub 2} = 1.049 {+-} 0.002 R{sub Sun }. The effective temperatures are 5900 K (fixed) and 5843 K, and the iron abundance, [Fe/H], is estimated to be +0.07. A comparison with evolutionary tracks suggests that the system may be even more metal rich. The components rotate with periods of 8.4 days, significantly faster than the predicted pseudosynchronous period of 12.7 days. We see evidence that one or both components have cool spots. Both stars are close to the zero-age main sequence and are about 1.0 Gyr old.« less

A search for tight hierarchical triple systems amongst the eclipsing binaries in the CoRoT fields

NASA Astrophysics Data System (ADS)

Hajdu, T.; Borkovits, T.; Forgács-Dajka, E.; Sztakovics, J.; Marschalkó, G.; Benkő, J. M.; Klagyivik, P.; Sallai, M. J.

2017-10-01

We report a comprehensive search for hierarchical triple stellar system candidates amongst eclipsing binaries (EBs) observed by the CoRoT spacecraft. We calculate and check eclipse timing variation (ETV) diagrams for almost 1500 EBs in an automated manner. We identify five relatively short period Algol systems for which our combined light-curve and complex ETV analyses (including both the light-travel time effect and short-term dynamical third-body perturbations) resulted in consistent third-body solutions. The computed periods of the outer bodies are between 82 and 272 d (with an alternative solution of 831 d for one of the targets). We find that the inner and outer orbits are near coplanar in all but one case. The dynamical masses of the outer subsystems determined from the ETV analyses are consistent with both the results of our light-curve analyses and the spectroscopic information available in the literature. One of our candidate systems exhibits outer eclipsing events as well, the locations of which are in good agreement with the ETV solution. We also report another certain triply eclipsing triple system that, however, is lacking a reliable ETV solution due to the very short time range of the data, and four new blended systems (composite light curves of two EBs each), where we cannot decide whether the components are gravitationally bounded or not. Amongst these blended systems, we identify the longest period and highest eccentricity EB in the entire CoRoT sample.

The EBLM project. I. Physical and orbital parameters, including spin-orbit angles, of two low-mass eclipsing binaries on opposite sides of the brown dwarf limit

NASA Astrophysics Data System (ADS)

Triaud, A. H. M. J.; Hebb, L.; Anderson, D. R.; Cargile, P.; Collier Cameron, A.; Doyle, A. P.; Faedi, F.; Gillon, M.; Gomez Maqueo Chew, Y.; Hellier, C.; Jehin, E.; Maxted, P.; Naef, D.; Pepe, F.; Pollacco, D.; Queloz, D.; Ségransan, D.; Smalley, B.; Stassun, K.; Udry, S.; West, R. G.

2013-01-01

This paper introduces a series of papers aiming to study the dozens of low-mass eclipsing binaries (EBLM), with F, G, K primaries, that have been discovered in the course of the WASP survey. Our objects are mostly single-line binaries whose eclipses have been detected by WASP and were initially followed up as potential planetary transit candidates. These have bright primaries, which facilitates spectroscopic observations during transit and allows the study of the spin-orbit distribution of F, G, K+M eclipsing binaries through the Rossiter-McLaughlin effect. Here we report on the spin-orbit angle of WASP-30b, a transiting brown dwarf, and improve its orbital parameters. We also present the mass, radius, spin-orbit angle and orbital parameters of a new eclipsing binary, J1219-39b (1SWAPJ121921.03-395125.6, TYC 7760-484-1), which, with a mass of 95 ± 2 Mjup, is close to the limit between brown dwarfs and stars. We find that both objects have projected spin-orbit angles aligned with their primaries' rotation. Neither primaries are synchronous. J1219-39b has a modestly eccentric orbit and is in agreement with the theoretical mass-radius relationship, whereas WASP-30b lies above it. Using WASP-South photometric observations (Sutherland, South Africa) confirmed with radial velocity measurement from the CORALIE spectrograph, photometry from the EulerCam camera (both mounted on the Swiss 1.2 m Euler Telescope), radial velocities from the HARPS spectrograph on the ESO's 3.6 m Telescope (prog ID 085.C-0393), and photometry from the robotic 60 cm TRAPPIST telescope, all located at ESO, La Silla, Chile. The data is publicly available at the CDS Strasbourg and on demand to the main author.Tables A.1-A.3 are available in electronic form at http://www.aanda.orgPhotometry tables are only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/549/A18

New variable stars discovered in the fields of three Galactic open clusters using the VVV survey

NASA Astrophysics Data System (ADS)

Palma, T.; Minniti, D.; Dékány, I.; Clariá, J. J.; Alonso-García, J.; Gramajo, L. V.; Ramírez Alegría, S.; Bonatto, C.

2016-11-01

This project is a massive near-infrared (NIR) search for variable stars in highly reddened and obscured open cluster (OC) fields projected on regions of the Galactic bulge and disk. The search is performed using photometric NIR data in the J-, H- and Ks- bands obtained from the Vista Variables in the Vía Láctea (VVV) Survey. We performed in each cluster field a variability search using Stetson's variability statistics to select the variable candidates. Later, those candidates were subjected to a frequency analysis using the Generalized Lomb-Scargle and the Phase Dispersion Minimization algorithms. The number of independent observations range between 63 and 73. The newly discovered variables in this study, 157 in total in three different known OCs, are classified based on their light curve shapes, periods, amplitudes and their location in the corresponding color-magnitude (J -Ks ,Ks) and color-color (H -Ks , J - H) diagrams. We found 5 possible Cepheid stars which, based on the period-luminosity relation, are very likely type II Cepheids located behind the bulge. Among the newly discovered variables, there are eclipsing binaries, δ Scuti, as well as background RR Lyrae stars. Using the new version of the Wilson & Devinney code as well as the "Physics Of Eclipsing Binaries" (PHOEBE) code, we analyzed some of the best eclipsing binaries we discovered. Our results show that these studied systems turn out to be ranging from detached to double-contact binaries, with low eccentricities and high inclinations of approximately 80°. Their surface temperatures range between 3500 K and 8000 K.

A photometric study of the eclipsing binary RX Hercules

NASA Technical Reports Server (NTRS)

Jeffreys, K. W.

1980-01-01

A new photoelectric light curve of RX Hercules, a binary system with similar components, has been analyzed using Wood's computer model. RX Her, using Popper's spectroscopic mass ratio of q = 0.8472, turned out to be composed of a dimmer AO component and a larger B9.5 component. This detached system, upon analysis of the residuals in secondary minimum, shows some asymmetry during ingress which then disappears just before secondary minimum. The eccentricity e = 0.022 determined in this study is a little larger than previously published values of e = 0.018. In combination with the spectroscopic analysis of Popper, and ubvy data of Olson and Hill and Hilditch new photometric elements for RX Her were found.

Observations and light curve solutions of three ultrashort-period W UMa binaries

NASA Astrophysics Data System (ADS)

Kjurkchieva, Diana P.; Michel, Raul; Popov, Velimir A.; Deras, Dan

2018-07-01

Photometric observations in V, Rc and Ic bands of the ultrashort-period W UMa binaries 1SWASP J044132.96+440613.7, 1SWASP J052926.88+461147.5 and NSVS 2175434 are presented. The results from the modeling and analysis of our observations reveal that: (i) All targets undergo total eclipses and their photometric mass ratios should be accepted with confidence; (ii) All stellar components are late-type dwarfs; (iii) The temperature difference of target components does not exceed 150 K; (iv) All targets have overcontact configurations with fill-out factor around 0.24; (v) The orbit of NSVS 2175434 is slightly eccentric which is unusual for such an ultrashort-period binary; (vi) The orbital periods of all targets were improved. Masses, radii and luminosities of the stellar components were estimated by the empirical relation "period, orbital axis" for short- and ultrashort-period binaries.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gomez Maqueo Chew, Yilen; Stassun, Keivan G.; Hebb, Leslie

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.more » 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 difference.« less

Photometric Study of the near-contact short period Algol system, AK Canis Minoris

NASA Astrophysics Data System (ADS)

Samec, Ronald G.; McDermith, Richard J.; Gray, Jamison D.; Carrigan, Brian

1995-05-01

As a part of our departments new undergraduate research program, we are surveying the eccentric eclipsing binary (EEB) candidates of Hegedus (1988). AK CMi is listed as a system with a displaced secondary. The observations were taken 10 to 15 February 1994, inclusive, at Lowell Obsevatory, Flagstaff, Arizona. A thermoelectrically cooled EMI 6256S ( S-13 cathode) PMT was used in conjunction with the 0.78 m National Undergraduate Research Observatory reflector. Two precision epochs of minimicrons light were determined from the observations made during primary and secondary eclipses. They are: Min I = 2449396.7032(5) and Min II = 2449395.8546(3). Targeting the last twenty-three years of data, we calculated improved linear and quadratic ephemerides. The quadratic term, -1.0(2)E-10, suggests that AK CMi is undergoing a continuous period decrease. This may be due to magnetic braking arising from the fast rotating solar-type secondary component. There is little evidence from the present light curves that AK CMi has a eccentric orbit. Assymetries near secondary minima possibly induced by an intermittent gas stream may be responsible for the classification of AK CMi as an EEB. The light curve solution reveals that AK CMi is a short period Algol with an A spectral-type primary component and an early K-type secondary. We calculated mass ratio of 0.5 and a secondary component fillout of 90% showing that AK CMi is a near contact binary.

Parkes radio searches of Fermi gamma-ray sources and millisecond pulsar discoveries

DOE Office of Scientific and Technical Information (OSTI.GOV)

Camilo, F.; Kerr, M.; Ray, P. S.

In a search with the Parkes radio telescope of 56 unidentified Fermi-Large Area Telescope (LAT) gamma-ray sources, we have detected 11 millisecond pulsars (MSPs), 10 of them discoveries, of which five were reported by Kerr et al. We did not detect radio pulsations from six other pulsars now known in these sources. We also describe the completed survey, which included multiple observations of many targets conducted to minimize the impact of interstellar scintillation, acceleration effects in binary systems, and eclipses. We consider that 23 of the 39 remaining sources may still be viable pulsar candidates. Furthermore, we present timing solutions and polarimetry for five of the MSPs and gamma-ray pulsations for PSR J1903–7051 (pulsations for five others were reported in the second Fermi-LAT catalog of gamma-ray pulsars). Two of the new MSPs are isolated and five are inmore » $$\\gt 1$$ day circular orbits with 0.2–0.3 $${M}_{\\odot }$$ presumed white dwarf companions. PSR J0955–6150, in a 24 day orbit with a $$\\approx 0.25$$ $${M}_{\\odot }$$ companion but eccentricity of 0.11, belongs to a recently identified class of eccentric MSPs. PSR J1036–8317 is in an 8 hr binary with a $$\\gt 0.14$$ $${M}_{\\odot }$$ companion that is probably a white dwarf. PSR J1946–5403 is in a 3 hr orbit with a $$\\gt 0.02$$ $${M}_{\\odot }$$ companion with no evidence of radio eclipses.« less

Parkes radio searches of Fermi gamma-ray sources and millisecond pulsar discoveries

DOE PAGES

Camilo, F.; Kerr, M.; Ray, P. S.; ...

2015-09-02

In a search with the Parkes radio telescope of 56 unidentified Fermi-Large Area Telescope (LAT) gamma-ray sources, we have detected 11 millisecond pulsars (MSPs), 10 of them discoveries, of which five were reported by Kerr et al. We did not detect radio pulsations from six other pulsars now known in these sources. We also describe the completed survey, which included multiple observations of many targets conducted to minimize the impact of interstellar scintillation, acceleration effects in binary systems, and eclipses. We consider that 23 of the 39 remaining sources may still be viable pulsar candidates. Furthermore, we present timing solutions and polarimetry for five of the MSPs and gamma-ray pulsations for PSR J1903–7051 (pulsations for five others were reported in the second Fermi-LAT catalog of gamma-ray pulsars). Two of the new MSPs are isolated and five are inmore » $$\\gt 1$$ day circular orbits with 0.2–0.3 $${M}_{\\odot }$$ presumed white dwarf companions. PSR J0955–6150, in a 24 day orbit with a $$\\approx 0.25$$ $${M}_{\\odot }$$ companion but eccentricity of 0.11, belongs to a recently identified class of eccentric MSPs. PSR J1036–8317 is in an 8 hr binary with a $$\\gt 0.14$$ $${M}_{\\odot }$$ companion that is probably a white dwarf. PSR J1946–5403 is in a 3 hr orbit with a $$\\gt 0.02$$ $${M}_{\\odot }$$ companion with no evidence of radio eclipses.« less

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zasche, P.; Juryšek, J.; Nemravová, J.

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 similarmore » 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.« less

THE VARYING LIGHT CURVE AND TIMINGS OF THE ULTRASHORT-PERIOD CONTACT BINARY KIC 9532219

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, Jae Woo; Hong, Kyeongsoo; Koo, Jae-Rim

2016-03-20

KIC 9532219 is a W UMa-type eclipsing binary with an orbital period of 0.1981549 days that is below the short-period limit (∼0.22 days) of the period distribution for contact binaries. The Kepler light curve of the system exhibits striking changes in both eclipse depths and light maxima. Applying third-body and spot effects, the light-curve synthesis indicates that the eclipsing pair is currently in a marginal contact stage with a mass ratio of q = 1.20, an orbital inclination of i = 66.°0, a temperature difference of T{sub 1}–T{sub 2} = 172 K, and a third light of l{sub 3} = 75.9%.more » To understand the light variations with time, we divided up the light curve into 312 segments and analyzed them separately. The results reveal that variation of eclipse depth is primarily caused by changing amounts of contamination due to the nearby star KIC 9532228 between the Kepler Quarters and that the variable O’Connell effect originates from the starspot activity on the less massive primary component. Based on our light-curve timings, a period study of KIC 9532219 indicates that the orbital period has varied as a combination of a downward parabola and a light-travel-time (LTT) effect due to a third body, which has a period of 1196 days and a minimum mass of 0.0892 M{sub ⊙} in an orbit of eccentricity 0.150. The parabolic variation could be a small part of a second LTT orbit due to a fourth component in a wider orbit, instead of either mass transfer or angular momentum loss.« less

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

NASA Astrophysics Data System (ADS)

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 on randomized training sets. Results: We obtain excellent results (about 5% global error rate) with classification into light curve morphology classes on the Hipparcos data. The classification into system morphology classes using the Catalog and Atlas of Eclipsing binaries (CALEB) has a higher error rate (about 10.5%), most importantly due to the (sometimes strong) similarity of the photometric light curves originating from physically different systems. When trained on CALEB and then applied to Kepler-detected eclipsing binaries subsampled according to Gaia observing times, LDA and SOM provide tractable, easy-to-visualize subspaces of the full (functional) space of light curves that summarize the most important phenomenological elements of the individual light curves. The sequence of light curves ordered by their first linear discriminant coefficient is compared to results obtained using local linear embedding. The SOM method proves able to find a 2-dimensional embedded surface in the space of the light curves which separates the system morphology classes in its different regions, and also identifies a few other phenomena, such as the asymmetry of the light curves due to spots, eccentric systems, and systems with a single eclipse. Furthermore, when data from other surveys are projected to the same SOM surface, the resulting map yields a good overview of the general biases and distortions due to differences in time sampling or population.

The extraneous eclipses on binary light curves: KIC 5255552, KIC 10091110, and KIC 11495766

NASA Astrophysics Data System (ADS)

Zhang, J.; Qian, S. B.; Wang, S. M.; Sun, L. L.; Wu, Y.; Jiang, L. Q.

2018-03-01

Aims: We aim to find more eclipsing multiple systems and obtain their parameters, thus increasing our understanding of multiple systems. Methods: The extraneous eclipses on the Kepler binary light curves indicating extraneous bodies were searched. The binary light curves were analyzed using the binary model, and the extraneous eclipses were studied on their periodicity and shape changes. Results: Three binaries with extraneous eclipses on the binary light curves were found and studied based on the Kepler observations. The object KIC 5255552 is an eclipsing triple system with a fast changing inner binary and an outer companion uncovered by three groups of extraneous eclipses of 862.1(±0.1) d period. The KIC 10091110 is suggested to be a double eclipsing binary system with several possible extraordinary coincidences: the two binaries share similar extremely small mass ratios (0.060(13) and 0.0564(18)), similar mean primary densities (0.3264(42) ρ⊙ and 0.3019(28) ρ⊙), and, most notably, the ratio of the two binaries' periods is very close to integer 2 (8.5303353/4.2185174 = 2.022). The KIC 11495766 is a probable triple system with a 120.73 d period binary and (at least) one non-eclipse companion. Furthermore, very close to it in the celestial sphere, there is a blended background stellar binary of 8.3404432 d period. A first list of 25 eclipsing multiple candidates is presented, with the hope that it will be beneficial for study of eclipsing multiples.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Conroy, Kyle E.; Stassun, Keivan G.; Prša, Andrej

2014-02-01

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 levelsmore » 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.« less

KEPLER ECLIPSING BINARIES WITH STELLAR COMPANIONS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gies, D. R.; Matson, R. A.; Guo, Z.

2015-12-15

Many short-period binary stars have distant orbiting companions that have played a role in driving the binary components into close separation. Indirect detection of a tertiary star is possible by measuring apparent changes in eclipse times of eclipsing binaries as the binary orbits the common center of mass. Here we present an analysis of the eclipse timings of 41 eclipsing binaries observed throughout the NASA Kepler mission of long duration and precise photometry. This subset of binaries is characterized by relatively deep and frequent eclipses of both stellar components. We present preliminary orbital elements for seven probable triple stars amongmore » this sample, and we discuss apparent period changes in seven additional eclipsing binaries that may be related to motion about a tertiary in a long period orbit. The results will be used in ongoing investigations of the spectra and light curves of these binaries for further evidence of the presence of third stars.« less

Evaluating Gaia performances on eclipsing binaries. IV. Orbits and stellar parameters for SV Cam, BS Dra and HP Dra

NASA Astrophysics Data System (ADS)

Milone, E. F.; Munari, U.; Marrese, P. M.; Williams, M. D.; Zwitter, T.; Kallrath, J.; Tomov, T.

2005-10-01

This is the fourth in a series of papers that aim both to provide reasonable orbits for a number of eclipsing binaries and to evaluate the expected performance of Gaia of these objects and the accuracy that is achievable in the determination of such fundamental stellar parameters as mass and radius. In this paper, we attempt to derive the orbits and physical parameters for three eclipsing binaries in the mid-F to mid-G spectral range. As for previous papers, only the H_P, V_T, BT photometry from the Hipparcos/Tycho mission and ground-based radial velocities from spectroscopy in the region 8480-8740 Å are used in the analyses. These data sets simulate the photometric and spectroscopic data that are expected to be obtained by Gaia, the approved ESA Cornerstone mission to be launched in 2011. The systems targeted in this paper are SV Cam, BS Dra and HP Dra. SV Cam and BS Dra have been studied previously, allowing comparisons of the derived parameters with those from full scale and devoted ground-based investigations. HP Dra has no published orbital solution. SV Cam has a β Lyrae type light curve and the others have Algol-like light curves. SV Cam has the complication of light curve anomalies, usually attributed to spots; BS Dra has non-solar metallicity, and HP Dra appears to have a small eccentricity and a sizeable time derivative in the argument of the periastron. Thus all three provide interesting and different test cases.

The Orbital and Physical Parameters, and the Distance of the Eclipsing Binary System OGLE-LMC-ECL-25658 in the Large Magellanic Cloud

NASA Astrophysics Data System (ADS)

Elgueta, S. S.; Graczyk, D.; Gieren, W.; Pietrzyński, G.; Thompson, I. B.; Konorski, P.; Pilecki, B.; Villanova, S.; Udalski, A.; Soszyński, I.; Suchomska, K.; Karczmarek, P.; Górski, M.; Wielgórski, P.

2016-08-01

We present an analysis of a new detached eclipsing binary, OGLE-LMC-ECL-25658, in the Large Magellanic Cloud (LMC). The system consists of two late G-type giant stars on an eccentric orbit with an orbital period of ˜200 days. The system shows total eclipses and the components have similar temperatures, making it ideal for a precise distance determination. Using multi-color photometric and high resolution spectroscopic data, we have performed an analysis of light and radial velocity curves simultaneously using the Wilson-Devinney code. We derived orbital and physical parameters of the binary with a high precision of \\lt 1%. The masses and surface metallicities of the components are virtually the same and equal to 2.23+/- 0.02 {M}⊙ and [{Fe}/{{H}}]\\=\\-0.63+/- 0.10 dex. However, their radii and rates of rotation show a distinct trace of differential stellar evolution. The distance to the system was calculated using an infrared calibration between V-band surface brightness and (V-K) color, leading to a distance modulus of (m-M)\\=\\18.452+/- 0.023 (statistical) ± 0.046 (systematic). Because OGLE-LMC-ECL-25658 is located relatively far from the LMC barycenter, we applied a geometrical correction for its position in the LMC disk using the van der Marel et al. model of the LMC. The resulting barycenter distance to the galaxy is {d}{{LMC}}\\=\\50.30+/- 0.53 (stat.) kpc, and is in perfect agreement with the earlier result of Pietrzyński et al.

Discovery of Three Self-lensing Binaries from Kepler

NASA Astrophysics Data System (ADS)

Kawahara, Hajime; Masuda, Kento; MacLeod, Morgan; Latham, David W.; Bieryla, Allyson; Benomar, Othman

2018-03-01

We report the discovery of three edge-on binaries with white dwarf (WD) companions that gravitationally magnify (instead of eclipsing) the light of their stellar primaries, as revealed by a systematic search for pulses with long periods in the Kepler photometry. We jointly model the self-lensing light curves and radial-velocity orbits to derive the WD masses, all of which are close to 0.6 solar masses. The orbital periods are long, ranging from 419 to 728 days, and the eccentricities are low, all less than 0.2. These characteristics are reminiscent of the orbits found for many blue stragglers in open clusters and the field, for which stable mass transfer due to Roche-lobe overflow from an evolving primary (now a WD) has been proposed as the formation mechanism. Because the actual masses for our three WD companions have been accurately determined, these self-lensing systems would provide excellent tests for models of interacting binaries.

HATS-36b and 24 Other Transiting/Eclipsing Systems from the HATSouth-K2 Campaign 7 Program

NASA Astrophysics Data System (ADS)

Bayliss, D.; Hartman, J. D.; Zhou, G.; Bakos, G. Á.; Vanderburg, A.; Bento, J.; Mancini, L.; Ciceri, S.; Brahm, R.; Jordán, A.; Espinoza, N.; Rabus, M.; Tan, T. G.; Penev, K.; Bhatti, W.; de Val-Borro, M.; Suc, V.; Csubry, Z.; Henning, Th.; Sarkis, P.; Lázár, J.; Papp, I.; Sári, P.

2018-03-01

We report on the result of a campaign to monitor 25 HATSouth candidates using the Kepler space telescope during Campaign 7 of the K2 mission. We discover HATS-36b (EPIC 215969174b, K2-145b), an eccentric (e=0.105+/- 0.028) hot Jupiter with a mass of 3.216+/- 0.062 {M}{{J}} and a radius of 1.235+/- 0.043 {R}{{J}}, which transits a solar-type G0V star (V = 14.386) in a 4.1752-day period. We also refine the properties of three previously discovered HATSouth transiting planets (HATS-9b, HATS-11b, and HATS-12b) and search the K2 data for TTVs and additional transiting planets in these systems. In addition, we also report on a further three systems that remain as Jupiter-radius transiting exoplanet candidates. These candidates do not have determined masses, however pass all of our other vetting observations. Finally, we report on the 18 candidates that we are now able to classify as eclipsing binary or blended eclipsing binary systems based on a combination of the HATSouth data, the K2 data, and follow-up ground-based photometry and spectroscopy. These range in periods from 0.7 day to 16.7 days, and down to 1.5 mmag in eclipse depths. Our results show the power of combining ground-based imaging and spectroscopy with higher precision space-based photometry, and serve as an illustration as to what will be possible when combining ground-based observations with TESS data.

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

NASA Astrophysics Data System (ADS)

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.

The Orbit of Transneptunian Binary Manwe and Thorondor and Their Upcoming Mutual Events

NASA Technical Reports Server (NTRS)

Grundy, W. M.; Benecchi, S. D.; Porter, S. B.; Noll, K. S.

2014-01-01

A new Hubble Space Telescope observation of the 7:4 resonant transneptunian binary system (385446) Manwe has shown that, of two previously reported solutions for the orbit of its satellite Thorondor, the prograde one is correct. The orbit has a period of 110.18 +/- 0.02 days, semimajor axis of 6670 +/- 40 km, and an eccentricity of 0.563 +/- 0.007. It will be viewable edge-on from the inner Solar System during 2015- 2017, presenting opportunities to observe mutual occultation and eclipse events. However, the number of observable events will be small, owing to the long orbital period and expected small sizes of the bodies relative to their separation. This paper presents predictions for events observable from Earth-based telescopes and discusses the associated uncertainties and challenges.

Interacting Winds in Eclipsing Symbiotic Systems - The Case Study of EG Andromedae

NASA Astrophysics Data System (ADS)

Calabrò, Emanuele

2014-03-01

We report the mathematical representation of the so called eccentric eclipse model, whose numerical solutions can be used to obtain the physical parameters of a quiescent eclipsing symbiotic system. Indeed the nebular region produced by the collision of the stellar winds should be shifted to the orbital axis because of the orbital motion of the system. This mechanism is not negligible, and it led us to modify the classical concept of an eclipse. The orbital elements obtained from spectroscopy and photometry of the symbiotic EG Andromedae were used to test the eccentric eclipse model. Consistent values for the unknown orbital elements of this symbiotic were obtained. The physical parameters are in agreement with those obtained by means of other simulations for this system.

Waveform model for an eccentric binary black hole based on the effective-one-body-numerical-relativity formalism

NASA Astrophysics Data System (ADS)

Cao, Zhoujian; Han, Wen-Biao

2017-08-01

Binary black hole systems are among the most important sources for gravitational wave detection. They are also good objects for theoretical research for general relativity. A gravitational waveform template is important to data analysis. An effective-one-body-numerical-relativity (EOBNR) model has played an essential role in the LIGO data analysis. For future space-based gravitational wave detection, many binary systems will admit a somewhat orbit eccentricity. At the same time, the eccentric binary is also an interesting topic for theoretical study in general relativity. In this paper, we construct the first eccentric binary waveform model based on an effective-one-body-numerical-relativity framework. Our basic assumption in the model construction is that the involved eccentricity is small. We have compared our eccentric EOBNR model to the circular one used in the LIGO data analysis. We have also tested our eccentric EOBNR model against another recently proposed eccentric binary waveform model; against numerical relativity simulation results; and against perturbation approximation results for extreme mass ratio binary systems. Compared to numerical relativity simulations with an eccentricity as large as about 0.2, the overlap factor for our eccentric EOBNR model is better than 0.98 for all tested cases, including spinless binary and spinning binary, equal mass binary, and unequal mass binary. Hopefully, our eccentric model can be the starting point to develop a faithful template for future space-based gravitational wave detectors.

Tatooines Future: The Eccentric Response of Keplers Circumbinary Planets to Common-Envelope Evolution of their Host Stars

NASA Technical Reports Server (NTRS)

Kostov, Veselin B.; Moore, Keavin; Tamayo, Daniel; Jayawardhana, Ray; Rinehart, Stephen A.

2016-01-01

Inspired by the recent Kepler discoveries of circumbinary planets orbiting nine close binary stars, we explore the fate of the former as the latter evolve off the main sequence. We combine binary star evolution models with dynamical simulations to study the orbital evolution of these planets as their hosts undergo common-envelope stages, losing in the process a tremendous amount of mass on dynamical timescales. Five of the systems experience at least one Roche-lobe overflow and common-envelope stages (Kepler-1647 experiences three), and the binary stars either shrink to very short orbits or coalesce; two systems trigger a double-degenerate supernova explosion. Kepler's circumbinary planets predominantly remain gravitationally bound at the end of the common-envelope phase, migrate to larger orbits, and may gain significant eccentricity; their orbital expansion can be more than an order of magnitude and can occur over the course of a single planetary orbit. The orbits these planets can reach are qualitatively consistent with those of the currently known post-common-envelope, eclipse-time variations circumbinary candidates. Our results also show that circumbinary planets can experience both modes of orbital expansion (adiabatic and non-adiabatic) if their host binaries undergo more than one common-envelope stage; multiplanet circumbinary systems like Kepler-47 can experience both modes during the same common-envelope stage. Additionally, unlike Mercury orbiting the Sun, a circumbinary planet with the same semi-major axis can survive the common envelope evolution of a close binary star with a total mass of 1 Solar Mass.

Dynamical habitability of planetary systems.

PubMed

Dvorak, Rudolf; Pilat-Lohinger, Elke; Bois, Eric; Schwarz, Richard; Funk, Barbara; Beichman, Charles; Danchi, William; Eiroa, Carlos; Fridlund, Malcolm; Henning, Thomas; Herbst, Tom; Kaltenegger, Lisa; Lammer, Helmut; Léger, Alain; Liseau, René; Lunine, Jonathan; Paresce, Francesco; Penny, Alan; Quirrenbach, Andreas; Röttgering, Huub; Selsis, Frank; Schneider, Jean; Stam, Daphne; Tinetti, Giovanna; White, Glenn J

2010-01-01

The problem of the stability of planetary systems, a question that concerns only multiplanetary systems that host at least two planets, is discussed. The problem of mean motion resonances is addressed prior to discussion of the dynamical structure of the more than 350 known planets. The difference with regard to our own Solar System with eight planets on low eccentricity is evident in that 60% of the known extrasolar planets have orbits with eccentricity e > 0.2. We theoretically highlight the studies concerning possible terrestrial planets in systems with a Jupiter-like planet. We emphasize that an orbit of a particular nature only will keep a planet within the habitable zone around a host star with respect to the semimajor axis and its eccentricity. In addition, some results are given for individual systems (e.g., Gl777A) with regard to the stability of orbits within habitable zones. We also review what is known about the orbits of planets in double-star systems around only one component (e.g., gamma Cephei) and around both stars (e.g., eclipsing binaries).

Finding binaries from phase modulation of pulsating stars with Kepler: V. Orbital parameters, with eccentricity and mass-ratio distributions of 341 new binaries

NASA Astrophysics Data System (ADS)

Murphy, Simon J.; Moe, Maxwell; Kurtz, Donald W.; Bedding, Timothy R.; Shibahashi, Hiromoto; Boffin, Henri M. J.

2018-03-01

The orbital parameters of binaries at intermediate periods (102-103 d) are difficult to measure with conventional methods and are very incomplete. We have undertaken a new survey, applying our pulsation timing method to Kepler light curves of 2224 main-sequence A/F stars and found 341 non-eclipsing binaries. We calculate the orbital parameters for 317 PB1 systems (single-pulsator binaries) and 24 PB2s (double-pulsators), tripling the number of intermediate-mass binaries with full orbital solutions. The method reaches down to small mass ratios q ≈ 0.02 and yields a highly homogeneous sample. We parametrize the mass-ratio distribution using both inversion and Markov-Chain Monte Carlo forward-modelling techniques, and find it to be skewed towards low-mass companions, peaking at q ≈ 0.2. While solar-type primaries exhibit a brown dwarf desert across short and intermediate periods, we find a small but statistically significant (2.6σ) population of extreme-mass-ratio companions (q < 0.1) to our intermediate-mass primaries. Across periods of 100-1500 d and at q > 0.1, we measure the binary fraction of current A/F primaries to be 15.4 per cent ± 1.4 per cent, though we find that a large fraction of the companions (21 per cent ± 6 per cent) are white dwarfs in post-mass-transfer systems with primaries that are now blue stragglers, some of which are the progenitors of Type Ia supernovae, barium stars, symbiotics, and related phenomena. Excluding these white dwarfs, we determine the binary fraction of original A/F primaries to be 13.9 per cent ± 2.1 per cent over the same parameter space. Combining our measurements with those in the literature, we find the binary fraction across these periods is a constant 5 per cent for primaries M1 < 0.8 M⊙, but then increases linearly with log M1, demonstrating that natal discs around more massive protostars M1 ≳ 1 M⊙ become increasingly more prone to fragmentation. Finally, we find the eccentricity distribution of the main-sequence pairs to be much less eccentric than the thermal distribution.

Coevolution of Binaries and Circumbinary Gaseous Disks

NASA Astrophysics Data System (ADS)

Fleming, David; Quinn, Thomas R.

2018-04-01

The recent discoveries of circumbinary planets by Kepler raise questions for contemporary planet formation models. Understanding how these planets form requires characterizing their formation environment, the circumbinary protoplanetary disk, and how the disk and binary interact. The central binary excites resonances in the surrounding protoplanetary disk that drive evolution in both the binary orbital elements and in the disk. To probe how these interactions impact both binary eccentricity and disk structure evolution, we ran N-body smooth particle hydrodynamics (SPH) simulations of gaseous protoplanetary disks surrounding binaries based on Kepler 38 for 10^4 binary orbital periods for several initial binary eccentricities. We find that nearly circular binaries weakly couple to the disk via a parametric instability and excite disk eccentricity growth. Eccentric binaries strongly couple to the disk causing eccentricity growth for both the disk and binary. Disks around sufficiently eccentric binaries strongly couple to the disk and develop an m = 1 spiral wave launched from the 1:3 eccentric outer Lindblad resonance (EOLR). This wave corresponds to an alignment of gas particle longitude of periastrons. We find that in all simulations, the binary semi-major axis decays due to dissipation from the viscous disk.

The EBLM Project. IV. Spectroscopic orbits of over 100 eclipsing M dwarfs masquerading as transiting hot Jupiters

NASA Astrophysics Data System (ADS)

Triaud, Amaury H. M. J.; Martin, David V.; Ségransan, Damien; Smalley, Barry; Maxted, Pierre F. L.; Anderson, David R.; Bouchy, François; Collier Cameron, Andrew; Faedi, Francesca; Gómez Maqueo Chew, Yilen; Hebb, Leslie; Hellier, Coel; Marmier, Maxime; Pepe, Francesco; Pollacco, Don; Queloz, Didier; Udry, Stéphane; West, Richard

2017-12-01

We present 2271 radial velocity measurements taken on 118 single-line binary stars, taken over eight years with the CORALIE spectrograph. The binaries consist of F/G/K primaries and M dwarf secondaries. They were initially discovered photometrically by the WASP planet survey, as their shallow eclipses mimic a hot Jupiter transit. The observations we present permit a precise characterisation of the binary orbital elements and mass function. With modelling of the primary star, this mass function is converted to a mass of the secondary star. In the future, this spectroscopic work will be combined with precise photometric eclipses to draw an empirical mass/radius relation for the bottom of the mass sequence. This has applications in both stellar astrophysics and the growing number of exoplanet surveys around M dwarfs. In particular, we have discovered 34 systems with a secondary mass below 0.2 M⊙, and so we will ultimately double the number of known very low-mass stars with well-characterised masses and radii. The quality of our data combined with the amplitude of the Doppler variations mean that we are able to detect eccentricities as small as 0.001 and orbital periods to sub-second precision. Our sample can revisit some earlier work on the tidal evolution of close binaries, extending it to low mass ratios. We find some exceptional binary systems that are eccentric at orbital periods below three days, while our longest circular orbit has a period of 10.4 days. Amongst our systems, we note one remarkable architecture in J1146-42 that boasts three stars within one astronomical unit. By collating the EBLM binaries with published WASP planets and brown dwarfs, we derive a mass spectrum with twice the resolution of previous work. We compare the WASP/EBLM sample of tightly bound orbits with work in the literature on more distant companions up to 10 AU. We note that the brown dwarf desert appears wider, as it carves into the planetary domain for our short-period orbits. This would mean that a significantly reduced abundance of planets begins at 3 MJup, well before the deuterium-burning limit. This may shed light on the formation and migration history of massive gas giants. Based on photometric observations with the SuperWASP and SuperWASP-South instruments and radial velocity measurement from the CORALIE spectrograph, mounted on the Swiss 1.2 m Euler Telescope, located at ESO, La Silla, Chile. The data is publicly available at the CDS Strasbourg and on demand to the main author.Radial velocity measurements 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/608/A129

Envelopes in eclipsing binary stars

NASA Technical Reports Server (NTRS)

Huang, S.

1972-01-01

Theoretical research on eclipsing binaries is presented. The specific areas of investigation are the following: (1) the relevance of envelopes to the study of the light curves of eclipsing binaries, (2) the disk envelope, and (3) the spherical envelope.

Measuring the Number of M Dwarfs per M Dwarf Using Kepler Eclipsing Binaries

NASA Astrophysics Data System (ADS)

Shan, Yutong; Johnson, John A.; Morton, Timothy D.

2015-11-01

We measure the binarity of detached M dwarfs in the Kepler field with orbital periods in the range of 1-90 days. Kepler’s photometric precision and nearly continuous monitoring of stellar targets over time baselines ranging from 3 months to 4 years make its detection efficiency for eclipsing binaries nearly complete over this period range and for all radius ratios. Our investigation employs a statistical framework akin to that used for inferring planetary occurrence rates from planetary transits. The obvious simplification is that eclipsing binaries have a vastly improved detection efficiency that is limited chiefly by their geometric probabilities to eclipse. For the M-dwarf sample observed by the Kepler Mission, the fractional incidence of eclipsing binaries implies that there are {0.11}-0.04+0.02 close stellar companions per apparently single M dwarf. Our measured binarity is higher than previous inferences of the occurrence rate of close binaries via radial velocity techniques, at roughly the 2σ level. This study represents the first use of eclipsing binary detections from a high quality transiting planet mission to infer binary statistics. Application of this statistical framework to the eclipsing binaries discovered by future transit surveys will establish better constraints on short-period M+M binary rate, as well as binarity measurements for stars of other spectral types.

Eccentric, nonspinning, inspiral, Gaussian-process merger approximant for the detection and characterization of eccentric binary black hole mergers

NASA Astrophysics Data System (ADS)

Huerta, E. A.; Moore, C. J.; Kumar, Prayush; George, Daniel; Chua, Alvin J. K.; Haas, Roland; Wessel, Erik; Johnson, Daniel; Glennon, Derek; Rebei, Adam; Holgado, A. Miguel; Gair, Jonathan R.; Pfeiffer, Harald P.

2018-01-01

We present ENIGMA, a time domain, inspiral-merger-ringdown waveform model that describes nonspinning binary black holes systems that evolve on moderately eccentric orbits. The inspiral evolution is described using a consistent combination of post-Newtonian theory, self-force and black hole perturbation theory. Assuming eccentric binaries that circularize prior to coalescence, we smoothly match the eccentric inspiral with a stand-alone, quasicircular merger, which is constructed using machine learning algorithms that are trained with quasicircular numerical relativity waveforms. We show that ENIGMA reproduces with excellent accuracy the dynamics of quasicircular compact binaries. We validate ENIGMA using a set of Einstein Toolkit eccentric numerical relativity waveforms, which describe eccentric binary black hole mergers with mass-ratios between 1 ≤q ≤5.5 , and eccentricities e0≲0.2 ten orbits before merger. We use this model to explore in detail the physics that can be extracted with moderately eccentric, nonspinning binary black hole mergers. In particular, we use ENIGMA to show that the gravitational wave transients GW150914, GW151226, GW170104, GW170814 and GW170608 can be effectively recovered with spinning, quasicircular templates if the eccentricity of these events at a gravitational wave frequency of 10 Hz satisfies e0≤{0.175 ,0.125 ,0.175 ,0.175 ,0.125 }, respectively. We show that if these systems have eccentricities e0˜0.1 at a gravitational wave frequency of 10 Hz, they can be misclassified as quasicircular binaries due to parameter space degeneracies between eccentricity and spin corrections. Using our catalog of eccentric numerical relativity simulations, we discuss the importance of including higher-order waveform multipoles in gravitational wave searches of eccentric binary black hole mergers.

Eclipsing binary stars with a δ Scuti component

NASA Astrophysics Data System (ADS)

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.

ON THE ORBIT OF EXOPLANET WASP-12b

DOE Office of Scientific and Technical Information (OSTI.GOV)

Campo, Christopher J.; Harrington, Joseph; Hardy, Ryan A.

We observed two secondary eclipses of the exoplanet WASP-12b using the Infrared Array Camera on the Spitzer Space Telescope. The close proximity of WASP-12b to its G-type star results in extreme tidal forces capable of inducing apsidal precession with a period as short as a few decades. This precession would be measurable if the orbit had a significant eccentricity, leading to an estimate of the tidal Love number and an assessment of the degree of central concentration in the planetary interior. An initial ground-based secondary-eclipse phase reported by Lopez-Morales et al. (0.510 {+-} 0.002) implied eccentricity at the 4.5{sigma} level.more » The spectroscopic orbit of Hebb et al. has eccentricity 0.049 {+-} 0.015, a 3{sigma} result, implying an eclipse phase of 0.509 {+-} 0.007. However, there is a well-documented tendency of spectroscopic data to overestimate small eccentricities. Our eclipse phases are 0.5010 {+-} 0.0006 (3.6 and 5.8 {mu}m) and 0.5006 {+-} 0.0007 (4.5 and 8.0 {mu}m). An unlikely orbital precession scenario invoking an alignment of the orbit during the Spitzer observations could have explained this apparent discrepancy, but the final eclipse phase of Lopez-Morales et al. (0.510 {+-}{sup +0.007}{sub -0.006}) is consistent with a circular orbit at better than 2{sigma}. An orbit fit to all the available transit, eclipse, and radial-velocity data indicates precession at <1{sigma}; a non-precessing solution fits better. We also comment on analysis and reporting for Spitzer exoplanet data in light of recent re-analyses.« less

Properties OF M31. V. 298 eclipsing binaries from PAndromeda

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, C.-H.; Koppenhoefer, J.; Seitz, S.

2014-12-10

The goal of this work is to conduct a photometric study of eclipsing binaries in M31. We apply a modified box-fitting algorithm to search for eclipsing binary candidates and determine their period. We classify these candidates into detached, semi-detached, and contact systems using the Fourier decomposition method. We cross-match the position of our detached candidates with the photometry from Local Group Survey and select 13 candidates brighter than 20.5 mag in V. The relative physical parameters of these detached candidates are further characterized with the Detached Eclipsing Binary Light curve fitter (DEBiL) by Devor. We will follow up the detachedmore » eclipsing binaries spectroscopically and determine the distance to M31.« less

What we learn from eclipsing binaries in the ultraviolet

NASA Technical Reports Server (NTRS)

Guinan, Edward F.

1990-01-01

Recent results on stars and stellar physics from IUE (International Ultraviolet Explorer) observations of eclipsing binaries are discussed. Several case studies are presented, including V 444 Cyg, Aur stars, V 471 Tau and AR Lac. Topics include stellar winds and mass loss, stellar atmospheres, stellar dynamos, and surface activity. Studies of binary star dynamics and evolution are discussed. The progress made with IUE in understanding the complex dynamical and evolutionary processes taking place in W UMa-type binaries and Algol systems is highlighted. The initial results of intensive studies of the W UMa star VW Cep and three representative Algol-type binaries (in different stages of evolution) focused on gas flows and accretion, are included. The future prospects of eclipsing binary research are explored. Remaining problems are surveyed and the next challenges are presented. The roles that eclipsing binaries could play in studies of stellar evolution, cluster dynamics, galactic structure, mass luminosity relations for extra galactic systems, cosmology, and even possible detection of extra solar system planets using eclipsing binaries are discussed.

Polar alignment of a protoplanetary disc around an eccentric binary II: Effect of binary and disc parameters

NASA Astrophysics Data System (ADS)

Martin, Rebecca G.; Lubow, Stephen H.

2018-06-01

In a recent paper Martin & Lubow showed that a circumbinary disc around an eccentric binary can undergo damped nodal oscillations that lead to the polar (perpendicular) alignment of the disc relative to the binary orbit. The disc angular momentum vector aligns to the eccentricity vector of the binary. We explore the robustness of this mechanism for a low mass disc (0.001 of the binary mass) and its dependence on system parameters by means of hydrodynamic disc simulations. We describe how the evolution depends upon the disc viscosity, temperature, size, binary mass ratio, orbital eccentricity and inclination. We compare results with predictions of linear theory. We show that polar alignment of a low mass disc may occur over a wide range of binary-disc parameters. We discuss the application of our results to the formation of planetary systems around eccentric binary stars.

HR 7578 - A K dwarf double-lined spectroscopic binary with peculiar abundances

NASA Technical Reports Server (NTRS)

Fekel, F. C., Jr.; Beavers, W. I.

1983-01-01

The number of double-lined K and M dwarf binaries which is currently known is quite small, only a dozen or less of each type. The HR 7578 system was classified as dK5 on the Mount Wilson system and as K2 V on the MK ystem. A summary of radial-velocity measurements including the observatory and weight of each observation is given in a table. The star with the stronger lines has been called component A. The final orbital element solution with all observations appropriately weighted was computed with a differential corrections computer program described by Barker et al. (1967). The program had been modified for the double-lined case. Of particular interest are the very large eccentricity of the system and the large minimum masses for each component. These large minimum masses suggest that eclipses may be detectable despite the relatively long period and small radii of the stars.

Four New Binary Stars in the Field of CL Aurigae. II

NASA Astrophysics Data System (ADS)

Kim, Chun-Hwey; Lee, Jae Woo; Duck, Hyun Kim; Andronov, Ivan L.

2010-12-01

We report on a discovery of four new variable stars (USNO-B1.0 1234-0103195, 1235- 0097170, 1236-0100293 and 1236-0100092) in the field of CL Aur. The stars are classified as eclipsing binary stars with orbital periods of 0.5137413(23) (EW type), 0.8698365(26) (EA) and 4.0055842(40) (EA with a significant orbital eccentricity), respectively. The fourth star (USNO-B1.0 1236-0100092) showed only one partial ascending branch of the light curves, although 22 nights were covered at the 61-cm telescope at the Sobaeksan Optical Astronomy Observatory (SOAO) in Korea. Fourteen minima timings for these stars are published separately. In an addition to the original discovery paper (Kim et al. 2010), we discuss methodological problems and present results of mathematical modeling of the light curves using other methods, i.e. trigonometric polynomial fits and the newly developed fit "NAV" ("New Algol Variable").

Mind Your Ps and Qs: The Interrelation between Period (P) and Mass-ratio (Q) Distributions of Binary Stars

NASA Astrophysics Data System (ADS)

Moe, Maxwell; Di Stefano, Rosanne

2017-06-01

We compile observations of early-type binaries identified via spectroscopy, eclipses, long-baseline interferometry, adaptive optics, common proper motion, etc. Each observational technique is sensitive to companions across a narrow parameter space of orbital periods P and mass ratios q = {M}{comp}/M 1. After combining the samples from the various surveys and correcting for their respective selection effects, we find that the properties of companions to O-type and B-type main-sequence (MS) stars differ among three regimes. First, at short orbital periods P ≲ 20 days (separations a ≲ 0.4 au), the binaries have small eccentricities e ≲ 0.4, favor modest mass ratios < q> ≈ 0.5, and exhibit a small excess of twins q > 0.95. Second, the companion frequency peaks at intermediate periods log P (days) ≈ 3.5 (a ≈ 10 au), where the binaries have mass ratios weighted toward small values q ≈ 0.2-0.3 and follow a Maxwellian “thermal” eccentricity distribution. Finally, companions with long orbital periods log P (days) ≈ 5.5-7.5 (a ≈ 200-5000 au) are outer tertiary components in hierarchical triples and have a mass ratio distribution across q ≈ 0.1-1.0 that is nearly consistent with random pairings drawn from the initial mass function. We discuss these companion distributions and properties in the context of binary-star formation and evolution. We also reanalyze the binary statistics of solar-type MS primaries, taking into account that 30% ± 10% of single-lined spectroscopic binaries likely contain white dwarf companions instead of low-mass stellar secondaries. The mean frequency of stellar companions with q > 0.1 and log P (days) < 8.0 per primary increases from 0.50 ± 0.04 for solar-type MS primaries to 2.1 ± 0.3 for O-type MS primaries. We fit joint probability density functions f({M}1,q,P,e)\

V571 Lyr is a Multiple System (Abstract)

NASA Astrophysics Data System (ADS)

Billings, G.

2016-12-01

(Abstract only) V571 Lyr (GSC 3116-1047) was discovered by the ROTSE survey to be an EA-type eclipsing binary with 1.25-day period. Primary and secondary eclipses are very similar, with depth V = 0.58 magnitude. In 2000, the then-active AAVSO "EB Team" started observing it, to refine the period estimate. A few eclipses were readily found, and a revised period computed. Subsequent eclipses diverged from the revised linear ephemeris by more than the expected amount of error, so observations were continued. Now, more than 100 time-of-minimum observations, over 15 years, clearly show that V571 Lyr is a triple system, with a third-body orbital period of 5.013 ± 0.008 years, and eccentricity of 0.74 ± 0.03. Our orbit fit also yields a period for the close pair, of 1.252 596 66(6) days. After removing the third-body light-time effect, the eclipse-time residuals still show larger than expected scatter, and possibly non-randomness, perhaps due to significant starspots and/or additional bodies in the system. The color of the system is B-V = 0.52 ± 0.01, corresponding to spectral type F7V, and we obtained a spectrum that we classify as F7V ± 2. The mass function computed from the fitted third-body orbit yields a minimum mass of 1.0 ± 0.1 Msolar, corresponding to a spectral range of F9V to G5V for the third star. We assume the two stars of the close pair are very similar, so the remaining light in eclipses (59%) is consistent with total eclipses and 3rd light from a star slightly dimmer than each of the pair.

The Orbit and Position of the X-ray Pulsar XTE J1855-026: An Eclipsing Supergiant System

NASA Technical Reports Server (NTRS)

Corbet, Robin H. D.; Mukai, Koji; White, Nicholas E. (Technical Monitor)

2002-01-01

A pulse timing orbit has been obtained for the X-ray binary XTEJ1855-026 using observations made with the Proportional Counter Array on board the Rossi X-ray Timing Explorer. The mass function obtained of approximately 16 solar mass together with the detection of an extended near-total eclipse confirm that the primary star is supergiant as predicted. The orbital eccentricity is found to be very low with a best fit value of 0.04 +/- 0.02. The orbital period is also refined to be 6.0724 +/- 0.0009 days using an improved and extended light curve obtained with RXTE's All Sky Monitor. Observations with the ASCA satellite provide an improved source location of R.A.= 18 hr 55 min 31.3 sec, decl.= -02 deg 36 min 24.0 sec (2000) with an estimated systematic uncertainty of less than 12 min. A serendipitous new source, AX J1855.4-0232, was also discovered during the ASCA observations.

A1540-53, an eclipsing X-ray binary pulsator

NASA Technical Reports Server (NTRS)

Becker, R. H.; Swank, J. H.; Boldt, E. A.; Holt, S. S.; Serlemitsos, P. J.; Pravdo, S. H.; Saba, J. R.

1977-01-01

An eclipsing X-ray binary pulsator consistent with the location of A1540-53 has been observed. The source pulse period was 528.93 + or - 0.10 s. The binary nature is confirmed by a Doppler curve for the pulsation period. The eclipse angle of 30.5 + or - 3 deg and the 4-hour transition to and from eclipse suggest an early-type giant or supergiant primary star.

Radial Velocities of 41 Kepler Eclipsing Binaries

NASA Astrophysics Data System (ADS)

Matson, Rachel A.; Gies, Douglas R.; Guo, Zhao; Williams, Stephen J.

2017-12-01

Eclipsing binaries are vital for directly determining stellar parameters without reliance on models or scaling relations. Spectroscopically derived parameters of detached and semi-detached binaries allow us to determine component masses that can inform theories of stellar and binary evolution. Here we present moderate resolution ground-based spectra of stars in close binary systems with and without (detected) tertiary companions observed by NASA’s Kepler mission and analyzed for eclipse timing variations. We obtain radial velocities and spectroscopic orbits for five single-lined and 35 double-lined systems, and confirm one false positive eclipsing binary. For the double-lined spectroscopic binaries, we also determine individual component masses and examine the mass ratio {M}2/{M}1 distribution, which is dominated by binaries with like-mass pairs and semi-detached classical Algol systems that have undergone mass transfer. Finally, we constrain the mass of the tertiary component for five double-lined binaries with previously detected companions.

A1540-53, an eclipsing X-ray binary pulsator

NASA Technical Reports Server (NTRS)

Becker, R. H.; Swank, J. H.; Boldt, E. A.; Holt, S. S.; Pravdo, S. H.; Saba, J. R.; Serlemitsos, P. J.

1977-01-01

An eclipsing X-ray binary pulsator consistent with the location of A1540-53 was observed. The source pulse period was 528.93 plus or minus 0.10 seconds. The binary nature is confirmed by a Doppler curve for the pulsation period. The eclipse angle of 30.5 deg plus or minus 3 deg and the 4 h transition to and from eclipse suggest an early type, giant or supergiant, primary star.

A Photometric Study of the Eclipsing Binary Star PY Boötis

NASA Astrophysics Data System (ADS)

Michaels, E. J.

2016-12-01

Presented here are the first precision multi-band CCD photometry of the eclipsing binary star PY Boötis. Best-fit stellar models were determined by analyzing the light curves with the Wilson-Devinney program. Asymmetries in the light curves were interpreted as resulting from magnetic activity which required spots to be included in the model. The resulting model is consistent with a W-type contact eclipsing binary having total eclipses.

The K2 M67 Study: A Curiously Young Star in an Eclipsing Binary in an Old Open Cluster

NASA Astrophysics Data System (ADS)

Sandquist, Eric L.; Mathieu, Robert D.; Quinn, Samuel N.; Pollack, Maxwell L.; Latham, David W.; Brown, Timothy M.; Esselstein, Rebecca; Aigrain, Suzanne; Parviainen, Hannu; Vanderburg, Andrew; Stello, Dennis; Somers, Garrett; Pinsonneault, Marc H.; Tayar, Jamie; Orosz, Jerome A.; Bedin, Luigi R.; Libralato, Mattia; Malavolta, Luca; Nardiello, Domenico

2018-04-01

We present an analysis of a slightly eccentric (e = 0.05), partially eclipsing, long-period (P = 69.73 days) main-sequence binary system (WOCS 12009, Sanders 1247) in the benchmark old open cluster M67. Using Kepler K2 and ground-based photometry, along with a large set of new and reanalyzed spectra, we derived highly precise masses (1.111 ± 0.015 and 0.748 ± 0.005 M ⊙) and radii (1.071 ± 0.008 ± 0.003 and 0.713 ± 0.019 ± 0.026 R ⊙, with statistical and systematic error estimates) for the stars. The radius of the secondary star is in agreement with theory. The primary, however, is approximately 15% smaller than reasonable isochrones for the cluster predict. Our best explanation is that the primary star was produced from the merger of two stars, as this can also account for the nondetection of photospheric lithium and its higher temperature relative to other cluster main-sequence stars at the same V magnitude. To understand the dynamical characteristics (low measured rotational line broadening of the primary star and low eccentricity of the current binary orbit), we believe that the most probable (but not the only) explanation is the tidal evolution of a close binary within a primordial triple system (possibly after a period of Kozai–Lidov oscillations), leading to merger approximately 1 Gyr ago. This star appears to be a future blue straggler that is being revealed as the cluster ages and the most massive main-sequence stars die out. Based on observations made at Kitt Peak National Observatory, National Optical Astronomy Observatory, which is operated by the Association of Universities for Research in Astronomy (AURA) under a cooperative agreement with the National Science Foundation; with the Tillinghast Reflector Echelle Spectrograph (TRES) on the 1.5 m Tillinghast telescope, located at the Smithsonian Astrophysical Observatory’s Fred L. Whipple Observatory on Mt. Hopkins in Arizona; the HARPS-N spectrograph on the Italian Telescopio Nazionale Galileo (TNG), operated on the island of La Palma by the INAF Fundacion Galileo Galilei (Spanish Observatory of Roque de los Muchachos of the IAC); and the Las Cumbres Observatory Global Telescope network.

A spectrum synthesis program for binary stars

NASA Technical Reports Server (NTRS)

Linnell, Albert P.; Hubeny, Ivan

1994-01-01

A new program produces synthetic spectra of binary stars at arbitrary values of orbital longitude, including longitudes of partial or complete eclipse. The stellar components may be distorted, either tidally or rotationally, or both. Either or both components may be rotating nonsynchronously. We illustrate the program performance with two cases: EE Peg, an eclipsing binary with small distortion, and SX Aur, an eclipsing binary that is close to contact.

The Optical Gravitational Lensing Experiment. Eclipsing Binary Stars in the Large Magellanic Cloud

NASA Astrophysics Data System (ADS)

Wyrzykowski, L.; Udalski, A.; Kubiak, M.; Szymanski, M.; Zebrun, K.; Soszynski, I.; Wozniak, P. R.; Pietrzynski, G.; Szewczyk, O.

2003-03-01

We present the catalog of 2580 eclipsing binary stars detected in 4.6 square degree area of the central parts of the Large Magellanic Cloud. The photometric data were collected during the second phase of the OGLE microlensing search from 1997 to 2000. The eclipsing objects were selected with the automatic search algorithm based on an artificial neural network. Basic statistics of eclipsing stars are presented. Also, the list of 36 candidates of detached eclipsing binaries for spectroscopic study and for precise LMC distance determination is provided. The full catalog is accessible from the OGLE Internet archive.

Effect of eccentricity on searches for gravitational waves from coalescing compact binaries in ground-based detectors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Brown, Duncan A.; Zimmerman, Peter J.

2010-01-15

Inspiralling compact binaries are expected to circularize before their gravitational-wave signals reach the sensitive frequency band of ground-based detectors. Current searches for gravitational waves from compact binaries using the LIGO and Virgo detectors therefore use circular templates to construct matched filters. Binary formation models have been proposed which suggest that some systems detectable by the LIGO-Virgo network may have non-negligible eccentricity. We investigate the ability of the restricted 3.5 post-Newtonian order TaylorF2 template bank, used by LIGO and Virgo to search for gravitational waves from compact binaries with masses M{<=}35M{sub {center_dot},} to detect binaries with nonzero eccentricity. We model themore » gravitational waves from eccentric binaries using the x-model post-Newtonian formalism proposed by Hinder et al.[I. Hinder, F. Hermann, P. Laguna, and D. Shoemaker, arXiv:0806.1037v1]. We find that small residual eccentricities (e{sub 0} < or approx. 0.05 at 40 Hz) do not significantly affect the ability of current LIGO searches to detect gravitational waves from coalescing compact binaries with total mass 2M{sub {center_dot}<}M<15M{sub {center_dot}.} For eccentricities e{sub 0} > or approx. 0.1, the loss in matched filter signal-to-noise ratio due to eccentricity can be significant and so templates which include eccentric effects will be required to perform optimal searches for such systems.« less

New prospects for observing and cataloguing exoplanets in well-detached binaries

NASA Astrophysics Data System (ADS)

Schwarz, R.; Funk, B.; Zechner, R.; Bazsó, Á.

2016-08-01

This paper is devoted to study the circumstances favourable to detect circumstellar and circumbinary planets in well-detached binary-star systems using eclipse timing variations (ETVs). We investigated the dynamics of well-detached binary star systems with a star separation from 0.5 to 3 au, to determine the probability of the detection of such variations with ground-based telescopes and space telescopes (like former missions CoRoT and Kepler and future space missions Plato, Tess and Cheops). For the chosen star separations both dynamical configurations (circumstellar and circumbinary) may be observable. We performed numerical simulations by using the full three-body problem as dynamical model. The dynamical stability and the ETVs are investigated by computing ETV maps for different masses of the secondary star and the exoplanet (Earth, Neptune and Jupiter size). In addition we changed the planet's and binary's eccentricities. We conclude that many amplitudes of ETVs are large enough to detect exoplanets in binary-star systems. As an application, we prepared statistics of the catalogue of exoplanets in binary star systems which we introduce in this article and compared the statistics with our parameter-space which we used for our calculations. In addition to these statistics of the catalogue we enlarged them by the investigation of well-detached binary star systems from several catalogues and discussed the possibility of further candidates.

Artificial Intelligence in Astronomy

NASA Astrophysics Data System (ADS)

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.

Eclipsing binary stars in the era of massive surveys First results and future prospects

NASA Astrophysics Data System (ADS)

Papageorgiou, Athanasios; Catelan, Márcio; Ramos, Rodrigo Contreras; Drake, Andrew J.

2017-09-01

Our thinking about eclipsing binary stars has undergone a tremendous change in the last decade. Eclipsing binary stars are one of nature's best laboratories for determining the fundamental physical properties of stars and thus for testing the predictions of theoretical models. Some of the largest ongoing variable star surveys include the Catalina Real-time Transient Survey (CRTS) and the VISTA Variables in the Vía Láctea survey (VVV). They both contain a large amount of photometric data and plenty of information about eclipsing binaries that wait to be extracted and exploited. Here we briefly describe our efforts in this direction.

THE CLUSTER AGES EXPERIMENT (CASE). VII. ANALYSIS OF TWO ECLIPSING BINARIES IN THE GLOBULAR CLUSTER NGC 6362

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kaluzny, J.; Rozyczka, M.; Schwarzenberg-Czerny, A.

2015-11-15

We use photometric and spectroscopic observations of the detached eclipsing binaries V40 and V41 in the globular cluster NGC 6362 to derive masses, radii, and luminosities of the component stars. The orbital periods of these systems are 5.30 and 17.89 days, respectively. The measured masses of the primary and secondary components (M{sub p}, M{sub s}) are (0.8337 ± 0.0063, 0.7947 ± 0.0048) M{sub ⊙} for V40 and (0.8215 ± 0.0058, 0.7280 ± 0.0047) M{sub ⊙} for V41. The measured radii (R{sub p}, R{sub s}) are (1.3253 ± 0.0075, 0.997 ± 0.013) R{sub ⊙} for V40 and (1.0739 ± 0.0048, 0.7307more » ± 0.0046) R{sub ⊙} for V41. Based on the derived luminosities, we find that the distance modulus of the cluster is 14.74 ± 0.04 mag—in good agreement with 14.72 mag obtained from color–magnitude diagram (CMD) fitting. We compare the absolute parameters of component stars with theoretical isochrones in mass–radius and mass–luminosity diagrams. For assumed abundances [Fe/H] = −1.07, [α/Fe] = 0.4, and Y = 0.25 we find the most probable age of V40 to be 11.7 ± 0.2 Gyr, compatible with the age of the cluster derived from CMD fitting (12.5 ± 0.5 Gyr). V41 seems to be markedly younger than V40. If independently confirmed, this result will suggest that V41 belongs to the younger of the two stellar populations recently discovered in NGC 6362. The orbits of both systems are eccentric. Given the orbital period and age of V40, its orbit should have been tidally circularized some ∼7 Gyr ago. The observed eccentricity is most likely the result of a relatively recent close stellar encounter.« less

Planet Formation in Stellar Binaries: How Disk Gravity Can Lower theFragmentation Barrier

NASA Astrophysics Data System (ADS)

Silsbee, Kedron; Rafikov, Roman R.

2014-11-01

Binary star systems present a challenge to current theories of planet formation. Perturbations from the companion star dynamically excite the protoplanetary disk, which can lead to destructive collisions between planetesimals, and prevent growth from 1 km to 100 km sized planetesimals. Despite this apparent barrier to coagulation, planets have been discovered within several small-separation (<20 AU), eccentric (eb 0.4) binaries, such as alpha Cen and gamma Cep. We address this problem by analytically exploring planetesimal dynamics under the simultaneous action of (1) binary perturbation, (2) gas drag (which tends to align planetesimal orbits), and (3), the gravity of an eccentric protoplanetary disk. We then use our dynamical solutions to assess the outcomes of planetesimal collisions (growth, destruction, erosion) for a variety of disk models. We find that planets in small-separation binaries can form at their present locations if the primordial protoplanetary disks were massive (>0.01M⊙) and not very eccentric (eccentricity of order several per cent at the location of planet). This constraint on the disk mass is compatible with the high masses of the giant planets in known gamma Cep-like binaries, which require a large mass reservoir for their formation. We show that for these massive disks, disk gravity is dominant over the gravity of the binary companion at the location of the observed planets. Therefore, planetesimal growth is highly sensitive to disk properties. The requirement of low disk eccentricity is in line with the recent hydrodynamic simulations that tend to show gaseous disks in eccentric binaries developing very low eccentricity, at the level of a few percent. A massive purely axisymmetric disk makes for a friendlier environment for planetesimal growth by driving rapid apsidal precession of planetesimals, and averaging out the eccentricity excitation from the binary companion. When the protoplanetary disk is eccentric we find that the most favorable conditions for planetesimal growth emerge when the disk is non-precessing and is apsidally aligned with the orbit of the binary.

The X-ray eclipse of the LMC binary CAL 87

NASA Technical Reports Server (NTRS)

Schmidtke, P. C.; Mcgrath, T. K.; Cowley, A. P.; Frattare, L. M.

1993-01-01

ROSAT-PSPC observations of the LMC eclipsing binary CAL 87 show a short-duration, shallow X-ray eclipse which coincides in phase with the primary optical minimum. Characteristics of the eclipse suggest the X-ray emitting region is only partially occulted. Similarities with the eclipse of the accretion-disk corona in X 1822-37 are discussed. However, no temperature variation through eclipse is found for CAL 87. A revised orbital period, combining published data and recent optical photometry, is given.

VizieR Online Data Catalog: OGLE eclipsing binaries in LMC (Wyrzykowski+, 2003)

NASA Astrophysics Data System (ADS)

Wyrzykowski, L.; Udalski, A.; Kubiak, M.; Szymanski, M.; Zebrun, K.; Soszynski, I.; Wozniak, P. R.; Pietrzynski, G.; Szewczyk, O.

2003-09-01

We present the catalog of 2580 eclipsing binary stars detected in 4.6 square degree area of the central parts of the Large Magellanic Cloud. The photometric data were collected during the second phase of the OGLE microlensing search from 1997 to 2000. The eclipsing objects were selected with the automatic search algorithm based on an artificial neural network. Basic statistics of eclipsing stars are presented. Also, the list of 36 candidates of detached eclipsing binaries for spectroscopic study and for precise LMC distance determination is provided. The full catalog is accessible from the OGLE Internet archive. (2 data files).

THE BANANA PROJECT. IV. TWO ALIGNED STELLAR ROTATION AXES IN THE YOUNG ECCENTRIC BINARY SYSTEM EP CRUCIS: PRIMORDIAL ORIENTATION AND TIDAL ALIGNMENT

DOE Office of Scientific and Technical Information (OSTI.GOV)

Albrecht, Simon; Winn, Joshua N.; Setiawan, Johny

With observations of the EP Cru system, we continue our series of measurements of spin-orbit angles in eclipsing binary star systems, the BANANA project (Binaries Are Not Always Neatly Aligned). We find a close alignment between the sky projections of the rotational and orbital angular momentum vectors for both stars ({beta}{sub p} = -1. Degree-Sign 8 {+-} 1. Degree-Sign 6 and |{beta}{sub s}| < 17 Degree-Sign ). We also derive precise absolute dimensions and stellar ages for this system. The EP Cru and DI Her systems provide an interesting comparison: they have similar stellar types and orbital properties, but DImore » Her is younger and has major spin-orbit misalignments, raising the question of whether EP Cru also had a large misalignment at an earlier phase of evolution. We show that tidal dissipation is an unlikely explanation for the good alignment observed today, because realignment happens on the same timescale as spin-orbit synchronization, and the stars in EP Cru are far from synchronization (they are spinning nine times too quickly). Therefore it seems that some binaries form with aligned axes, while other superficially similar binaries are formed with misaligned axes.« less

The OGLE Collection of Variable Stars. Over 450 000 Eclipsing and Ellipsoidal Binary Systems Toward the Galactic Bulge

NASA Astrophysics Data System (ADS)

Soszyński, I.; Pawlak, M.; Pietrukowicz, P.; Udalski, A.; Szymański, M. K.; Wyrzykowski, Ł.; Ulaczyk, K.; Poleski, R.; Kozłowski, S.; Skowron, D. M.; Skowron, J.; Mróz, P.; Hamanowicz, A.

2016-12-01

We present a collection of 450 598 eclipsing and ellipsoidal binary systems detected in the OGLE fields toward the Galactic bulge. The collection consists of binary systems of all types: detached, semi-detached, and contact eclipsing binaries, RS CVn stars, cataclysmic variables, HW Vir binaries, double periodic variables, and even planetary transits. For all stars we provide the I- and V-band time-series photometry obtained during the OGLE-II, OGLE-III, and OGLE-IV surveys. We discuss methods used to identify binary systems in the OGLE data and present several objects of particular interest.

The Search for Bright Variable Stars in Open Cluster NGC 6819.

NASA Astrophysics Data System (ADS)

Talamantes, Antonio; Sandquist, E. L.

2009-01-01

During this research period data was taken for seven nights at the 1m telescope at Mt. Laguna Observatory for the open cluster NGC 6819. For four of the nights data was taken using a V-band filter. For the three nights remaining nights the data was taken using an R-band filter. Photometry was done using the ISIS image subtraction package. Six new variable stars were located using these techniques. These variable types include a pulsating variable, five detached eclipsing binaries. Of the detached eclipsing binaries, three are near the cluster turnoff and two in the blue straggler region(and one of these has total eclipses). Nine previously known variables(six contact binaries, two detached eclipsing binaries and one near-contact binary) were also studied.

Properties of an eclipsing double white dwarf binary NLTT 11748

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kaplan, David L.; Walker, Arielle N.; Marsh, Thomas R.

2014-01-10

We present high-quality ULTRACAM photometry of the eclipsing detached double white dwarf binary NLTT 11748. This system consists of a carbon/oxygen white dwarf and an extremely low mass (<0.2 M {sub ☉}) helium-core white dwarf in a 5.6 hr orbit. To date, such extremely low-mass white dwarfs, which can have thin, stably burning outer layers, have been modeled via poorly constrained atmosphere and cooling calculations where uncertainties in the detailed structure can strongly influence the eventual fates of these systems when mass transfer begins. With precise (individual precision ≈1%), high-cadence (≈2 s), multicolor photometry of multiple primary and secondary eclipsesmore » spanning >1.5 yr, we constrain the masses and radii of both objects in the NLTT 11748 system to a statistical uncertainty of a few percent. However, we find that overall uncertainty in the thickness of the envelope of the secondary carbon/oxygen white dwarf leads to a larger (≈13%) systematic uncertainty in the primary He WD's mass. Over the full range of possible envelope thicknesses, we find that our primary mass (0.136-0.162 M {sub ☉}) and surface gravity (log (g) = 6.32-6.38; radii are 0.0423-0.0433 R {sub ☉}) constraints do not agree with previous spectroscopic determinations. We use precise eclipse timing to detect the Rømer delay at 7σ significance, providing an additional weak constraint on the masses and limiting the eccentricity to ecos ω = (– 4 ± 5) × 10{sup –5}. Finally, we use multicolor data to constrain the secondary's effective temperature (7600 ± 120 K) and cooling age (1.6-1.7 Gyr).« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Groot, Paul J., E-mail: pgroot@astro.ru.nl

In eclipsing binaries the stellar rotation of the two components will cause a rotational Doppler beaming during eclipse ingress and egress when only part of the eclipsed component is covered. For eclipsing binaries with fast spinning components this photometric analog of the well-known spectroscopic Rossiter-McLaughlin effect can exceed the strength of the orbital effect. Example light curves are shown for a detached double white dwarf binary, a massive O-star binary and a transiting exoplanet case, similar to WASP-33b. Inclusion of the rotational Doppler beaming in eclipsing systems is a prerequisite for deriving the correct stellar parameters from fitting high-quality photometricmore » light curves and can be used to determine stellar obliquities as well as, e.g., an independent measure of the rotational velocity in those systems that may be expected to be fully synchronized.« less

The early-type multiple system QZ Carinae

NASA Astrophysics Data System (ADS)

Mayer, P.; Lorenz, R.; Drechsel, H.; Abseim, A.

2001-02-01

We present an analysis of the early-type quadruple system QZ Car, consisting of an eclipsing and a non-eclipsing binary. The spectroscopic investigation is based on new high dispersion echelle and CAT/CES spectra of H and He lines. The elements for the orbit of the non-eclipsing pair could be refined. Lines of the brighter component of the eclipsing binary were detected in near-quadrature spectra, while signatures of the fainter component could be identified in only few spectra. Lines of the primary component of the non-eclipsing pair and of both components of the eclipsing pair were found to be variable in position and strength; in particular, the He ii 4686 emission line of the brighter eclipsing component is strongly variable. An ephemeris for the eclipsing binary QZ Car valid at present was derived Prim. Min. = hel. JD 2448687.16 + 5fd9991 * E. The relative orbit of the two binary constituents of the multiple system is discussed. In contrast to earlier investigations we found radial velocity changes of the systemic velocities of both binaries, which were used - together with an O-C analysis of the expected light-time effect - to derive approximate parameters of the mutual orbit of the two pairs. It is shown that this orbit and the distance to QZ Car can be further refined by minima timing and interferometry. Based on observations collected at the European Southern Observatory, La Silla, Chile.

Eclipsing Binaries in Open Clusters

NASA Astrophysics Data System (ADS)

Southworth, John; Clausen, Jens Viggo

2006-08-01

The study of detached eclipsing binaries in open clusters can provide stringent tests of theoretical stellar evolutionary models, which must simultaneously fit the masses, radii, and luminosities of the eclipsing stars and the radiative properties of every other star in the cluster. We review recent progress in such studies and discuss two unusually interesting objects currently under analysis. GV Carinae is an A0 m + A8 m binary in the Southern open cluster NGC 3532; its eclipse depths have changed by 0.1 mag between 1990 and 2001, suggesting that its orbit is being perturbed by a relatively close third body. DW Carinae is a high-mass unevolved B1 V + B1 V binary in the very young open cluster Collinder 228, and displays double-peaked emission in the centre of the Hα line which is characteristic of Be stars. We conclude by pointing out that the great promise of eclipsing binaries in open clusters can only be satisfied when both the binaries and their parent clusters are well-observed, a situation which is less common than we would like.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Parsons, S. G.; Marsh, T. R.; Gaensicke, B. T.

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 H{alpha} absorption line cores. These measurements, combined with the light curve information, yield white dwarf masses of M{sub 1}more » = 0.283 {+-} 0.064 M{sub sun} and M{sub 2} = 0.274 {+-} 0.034 M{sub 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.« less

Time Series Observations of the 2015 Eclipse of b Persei (not beta Persei) (Abstract)

NASA Astrophysics Data System (ADS)

Collins, D. F.

2016-06-01

(Abstract only) The bright (V = 4.6) ellipsoidal variable b Persei consists of a close non-eclipsing binary pair that shows a nearly sinusoidal light curve with a ~1.5 day period. This system also contains a third star that orbits the binary pair every 702 days. AAVSO observers recently detected the first ever optical eclipse of A-B binary pair by the third star as a series of snapshots (D. Collins, R. Zavala, J. Sanborn - AAVSO Spring Meeting, 2013); abstract published in Collins, JAAVSO, 41, 2, 391 (2013); b Per mis-printed as b Per therein. A follow-up eclipse campaign in mid-January 2015 recorded time-series observations. These new time-series observations clearly show multiple ingress and egress of each component of the binary system by the third star over the eclipse duration of 2 to 3 days. A simulation of the eclipse was created. Orbital and some astrophysical parameters were adjusted within constraints to give a reasonable fit to the observed light curve.

ON THE PULSATIONAL-ORBITAL-PERIOD RELATION OF ECLIPSING BINARIES WITH δ-SCT COMPONENTS

DOE Office of Scientific and Technical Information (OSTI.GOV)

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

2013-11-01

We have deduced a theoretical relation between the pulsation and orbital-periods of pulsating stars in close binaries based on their Roche lobe filling. It appears to be of a simple linear form, with the slope as a function of the pulsation constant, the mass ratio, and the filling factor for an individual system. Testing the data of 69 known eclipsing binaries containing δ-Sct-type components yields an empirical slope of 0.020 ± 0.006 for the P{sub pul}-P{sub orb} relation. We have further derived the upper limit of the P{sub pul}/P{sub orb} ratio for the δ-Sct stars in eclipsing binaries with amore » value of 0.09 ± 0.02. This value could serve as a criterion to distinguish whether or not a pulsator in an eclipsing binary pulsates in the p-mode. Applying the deduced P{sub pul}-P{sub orb} relation, we have computed the dominant pulsation constants for 37 δ-Sct stars in eclipsing systems with definite photometric solutions. These ranged between 0.008 and 0.033 days with a mean value of about 0.014 days, indicating that δ-Sct stars in eclipsing binaries mostly pulsate in the fourth or fifth overtones.« less

New Light Curves and Analysis of the Overcontact Binaries PP Lac and DK Sge

NASA Astrophysics Data System (ADS)

Sanders, S. J.; Hargis, J. R.; Bradstreet, D. H.

2004-12-01

As a by-product of the ongoing work with the Catalog and AtLas of Eclipsing Binaries database (CALEB; Bradstreet et al. 2004), several hundred eclipsing binary systems have been identified that have either unpublished or poor quality light curves. We present new V & Rc light curves for the overcontact systems PP Lac and DK Sge, both chosen because their deep eclipses (peak-to-peak amplitudes of nearly 0.7 mag) help constrain the light curve modelling. Data were obtained using the 41-cm telescope at the Eastern University Observatory equipped with an SBIG ST-10XME CCD. PP Lac (P= 0.40116 d) is a W-type contact binary with only one previously published light curve (Dumont & Maraziti 1990), but the data are sparse and almost non-existent at primary eclipse. Modelling of these data gave varying results; the published mass ratios differ by nearly 0.3. Our data confirms the noted differing eclipse depths but we find the primary eclipse to be total. We present a new light curve solution using Binary Maker 3 (Bradstreet & Steelman 2002) and Wilson-Devinney, finding the mass ratio to be well-constrained by the duration of total eclipse. A period study will be presented using previously existing and newly derived times of minimum light. DK Sge (P=0.62182 d) appears to be an A-type contact binary with no published light curve. The eclipses are partial, with the primary eclipse being deeper by about 0.08 mag. The maxima show evidence of a slight asymmetry, although the light curve appears to be repeatable over the 1 month of observations. We present the first light curve solution using Binary Maker 3 and Wilson-Devinney, but have limited mass ratio constraints due to the absence of radial velocity data. A period study will be presented using previously existing and newly derived times of minimum light.

On the development and applications of automated searches for eclipsing binary stars

NASA Astrophysics Data System (ADS)

Devor, Jonathan

Eclipsing binary star systems provide the most accurate method of measuring both the masses and radii of stars. Moreover, they enable testing tidal synchronization and circularization theories, as well as constraining models of stellar structure and dynamics. With the recent availability of large-scale multi-epoch photometric datasets, we are able to study eclipsing binary stars en masse. In this thesis, we analyzed 185,445 light curves from ten TrES fields, and 218,699 light curves from the OGLE II bulge fields. In order to manage such large quantities of data, we developed a pipeline with which we systematically identified eclipsing binaries, solved for their geometric orientations, and then found their components' absolute properties. Following this analysis, we assembled catalogs of eclipsing binaries with their models, computed statistical distributions of their properties, and located rare cases for further follow-up. Of particular importance are low-mass eclipsing binaries, which are rare, yet critical for resolving the ongoing mass-radius discrepancy between theoretical models and observations. To this end, we have discovered over a dozen new low-mass eclipsing binary candidates, and spectroscopically confirmed the masses of five of them. One of these confirmed candidates, T-Lyr1-17236, is especially interesting because of its uniquely long orbital period. We examined T-Lyr1-17236 in detail and found that it is consistent with the magnetic disruption hypothesis for explaining the observed mass-radius discrepancy. Both the source code of our pipeline and the complete list of our candidates are freely available.

A possible additional body in eclipsing binary system HS 2231+2441

NASA Astrophysics Data System (ADS)

Vidmachenko, A. P.; Shliakhetska, Ya. O.; Romanyuk, Ya. O.

2016-12-01

Analysis of the light curves of eclipsing binary systems HS 2231+2441, obtained with the 36-cm telescope, is made. In processing the photometric data on eclipses by method of timing, obtained evidence for the existence of a third body in the system.

Evidence for a planetary mass third body orbiting the binary star KIC 5095269

NASA Astrophysics Data System (ADS)

Getley, A. K.; Carter, B.; King, R.; O'Toole, S.

2017-07-01

In this paper, we report the evidence for a planetary mass body orbiting the close binary star KIC 5095269. This detection arose from a search for eclipse timing variations amongst the more than 2000 eclipsing binaries observed by Kepler. Light curve and periodic eclipse time variations have been analysed using systemic and a custom Binary Eclipse Timings code based on the Transit Analysis Package which indicates a 7.70 ± 0.08MJup object orbiting every 237.7 ± 0.1 d around a 1.2 M⊙ primary and a 0.51 M⊙ secondary in an 18.6 d orbit. A dynamical integration over 107 yr suggests a stable orbital configuration. Radial velocity observations are recommended to confirm the properties of the binary star components and the planetary mass of the companion.

On the period determination of ASAS eclipsing binaries

NASA Astrophysics Data System (ADS)

Mayangsari, L.; Priyatikanto, R.; Putra, M.

2014-03-01

Variable stars, or particularly eclipsing binaries, are very essential astronomical occurrence. Surveys are the backbone of astronomy, and many discoveries of variable stars are the results of surveys. All-Sky Automated Survey (ASAS) is one of the observing projects whose ultimate goal is photometric monitoring of variable stars. Since its first light in 1997, ASAS has collected 50,099 variable stars, with 11,076 eclipsing binaries among them. In the present work we focus on the period determination of the eclipsing binaries. Since the number of data points in each ASAS eclipsing binary light curve is sparse, period determination of any system is a not straightforward process. For 30 samples of such systems we compare the implementation of Lomb-Scargle algorithm which is an Fast Fourier Transform (FFT) basis and Phase Dispersion Minimization (PDM) method which is non-FFT basis to determine their period. It is demonstrated that PDM gives better performance at handling eclipsing detached (ED) systems whose variability are non-sinusoidal. More over, using semi-automatic recipes, we get better period solution and satisfactorily improve 53% of the selected object's light curves, but failed against another 7% of selected objects. In addition, we also highlight 4 interesting objects for further investigation.

The Optical Gravitational Lensing Experiment. Eclipsing Binary Stars in the Small Magellanic Cloud

NASA Astrophysics Data System (ADS)

Wyrzykowski, L.; Udalski, A.; Kubiak, M.; Szymanski, M. K.; Zebrun, K.; Soszynski, I.; Wozniak, P. R.; Pietrzynski, G.; Szewczyk, O.

2004-03-01

We present new version of the OGLE-II catalog of eclipsing binary stars detected in the Small Magellanic Cloud, based on Difference Image Analysis catalog of variable stars in the Magellanic Clouds containing data collected from 1997 to 2000. We found 1351 eclipsing binary stars in the central 2.4 square degree area of the SMC. 455 stars are newly discovered objects, not found in the previous release of the catalog. The eclipsing objects were selected with the automatic search algorithm based on the artificial neural network. The full catalog is accessible from the OGLE Internet archive.

Numerical Relativity Simulations of Compact Binary Populations in Dense Stellar Environments

NASA Astrophysics Data System (ADS)

Glennon, Derek Ray; Huerta, Eliu; Allen, Gabrielle; Haas, Roland; Seidel, Edward; NCSA Gravity Group

2018-01-01

We present a catalog of numerical relativity simulations that describe binary black hole mergers on eccentric orbits. These simulations have been obtained with the open source, Einstein Toolkit numerical relativity software, using the Blue Waters supercomputer. We use this catalog to quantify observables, such as the mass and spin of black holes formed by binary black hole mergers, as a function of eccentricity. This study is the first of its kind in the literature to quantify these astrophysical observables for binary black hole mergers with mass-ratios q<6, and eccentricities e<0.2. This study is an important step in understanding the properties of eccentric binary black hole mergers, and informs the use of gravitational wave observations to confirm or rule out the existence of compact binary populations in dense stellar environments.

Long-term eclipse timing of white dwarf binaries: an observational hint of a magnetic mechanism at work

NASA Astrophysics Data System (ADS)

Bours, M. C. P.; Marsh, T. R.; Parsons, S. G.; Dhillon, V. S.; Ashley, R. P.; Bento, J. P.; Breedt, E.; Butterley, T.; Caceres, C.; Chote, P.; Copperwheat, C. M.; Hardy, L. K.; Hermes, J. J.; Irawati, P.; Kerry, P.; Kilkenny, D.; Littlefair, S. P.; McAllister, M. J.; Rattanasoon, S.; Sahman, D. I.; Vučković, M.; Wilson, R. W.

2016-08-01

We present a long-term programme for timing the eclipses of white dwarfs in close binaries to measure apparent and/or real variations in their orbital periods. Our programme includes 67 close binaries, both detached and semi-detached and with M-dwarfs, K-dwarfs, brown dwarfs or white dwarfs secondaries. In total, we have observed more than 650 white dwarf eclipses. We use this sample to search for orbital period variations and aim to identify the underlying cause of these variations. We find that the probability of observing orbital period variations increases significantly with the observational baseline. In particular, all binaries with baselines exceeding 10 yr, with secondaries of spectral type K2 - M5.5, show variations in the eclipse arrival times that in most cases amount to several minutes. In addition, among those with baselines shorter than 10 yr, binaries with late spectral type (>M6), brown dwarf or white dwarf secondaries appear to show no orbital period variations. This is in agreement with the so-called Applegate mechanism, which proposes that magnetic cycles in the secondary stars can drive variability in the binary orbits. We also present new eclipse times of NN Ser, which are still compatible with the previously published circumbinary planetary system model, although only with the addition of a quadratic term to the ephemeris. Finally, we conclude that we are limited by the relatively short observational baseline for many of the binaries in the eclipse timing programme, and therefore cannot yet draw robust conclusions about the cause of orbital period variations in evolved, white dwarf binaries.

Massive eclipsing binary candidates

NASA Technical Reports Server (NTRS)

Garrison, R. F.; Schild, R. E.; Hiltner, W. A.

1983-01-01

New UBV data are provided for 63 southern OB stars which are either identified in the survey by Garrison, Hiltner, and Schild as having double lines or are known from Wood et al. to be eclipsing binaries. Twenty of the stars are known eclipsing variables. Four stars, not previously known as eclipsing, have both spectroscopic evidence of duplicity and significant photometric variations. Several additional stars have a marginally significant spread in V magnitude.

Secular dynamics of the triple system harboring PSR J0337+1715 and implications for the origin of its orbital configuration

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rafikov, Roman R., E-mail: rrr@astro.princeton.edu

2014-10-10

We explore secular dynamics of a recently discovered hierarchical triple system consisting of the radio pulsar PSR J0337+1715 and two white dwarfs (WDs). We show that three-body interactions endow the inner binary with a large forced eccentricity and suppress its apsidal precession, to about 24% of the rate due to the general relativity. However, precession rate is still quite sensitive to the non-Newtonian effects and may be used to constrain gravity theories if measured accurately. A small value of the free eccentricity of the inner binary e{sub i}{sup free}≈2.6×10{sup −5} and vanishing forced eccentricity of the outer, relatively eccentric binarymore » naturally result in their apsidal near-alignment. In addition, this triple system provides a unique opportunity to explore excitation of both eccentricity and inclination in neutron star-WD binaries, e.g., due to random torques caused by convective eddies in the WD progenitor. We show this process to be highly anisotropic and more effective at driving eccentricity rather than inclination. The outer binary eccentricity and e{sub i}{sup free} exceed by more than an order of magnitude the predictions of the eccentricity-period relation of Phinney, which is not uncommon. We also argue that the non-zero mutual inclination of the two binaries emerges at the end of the Roche lobe overflow of the outer (rather than the inner) binary.« less

VizieR Online Data Catalog: Kepler Mission. VII. Eclipsing binaries in DR3 (Kirk+, 2016)

NASA Astrophysics Data System (ADS)

Kirk, B.; Conroy, K.; Prsa, A.; Abdul-Masih, M.; Kochoska, A.; Matijevic, G.; Hambleton, K.; Barclay, T.; Bloemen, S.; Boyajian, T.; Doyle, L. R.; Fulton, B. J.; Hoekstra, A. J.; Jek, K.; Kane, S. R.; Kostov, V.; Latham, D.; Mazeh, T.; Orosz, J. A.; Pepper, J.; Quarles, B.; Ragozzine, D.; Shporer, A.; Southworth, J.; Stassun, K.; Thompson, S. E.; Welsh, W. F.; Agol, E.; Derekas, A.; Devor, J.; Fischer, D.; Green, G.; Gropp, J.; Jacobs, T.; Johnston, C.; Lacourse, D. M.; Saetre, K.; Schwengeler, H.; Toczyski, J.; Werner, G.; Garrett, M.; Gore, J.; Martinez, A. O.; Spitzer, I.; Stevick, J.; Thomadis, P. C.; Vrijmoet, E. H.; Yenawine, M.; Batalha, N.; Borucki, W.

2016-07-01

The Kepler Eclipsing Binary Catalog lists the stellar parameters from the Kepler Input Catalog (KIC) augmented by: primary and secondary eclipse depth, eclipse width, separation of eclipse, ephemeris, morphological classification parameter, and principal parameters determined by geometric analysis of the phased light curve. The previous release of the Catalog (Paper II; Slawson et al. 2011, cat. J/AJ/142/160) contained 2165 objects, through the second Kepler data release (Q0-Q2). In this release, 2878 objects are identified and analyzed from the entire data set of the primary Kepler mission (Q0-Q17). The online version of the Catalog is currently maintained at http://keplerEBs.villanova.edu/. A static version of the online Catalog associated with this paper is maintained at MAST https://archive.stsci.edu/kepler/eclipsing_binaries.html. (10 data files).

Spitzer Secondary Eclipses of HAT-P-13b

NASA Astrophysics Data System (ADS)

Hardy, Ryan A.; Harrington, J.; Hardin, M. R.; Madhusudhan, N.; Cubillos, P.; Blecic, J.; Bakos, G.; Hartman, J. D.

2013-10-01

HAT-P-13 b is a transiting hot Jupiter with a slightly eccentric orbit (e = 0.010) inhabiting a two-planet system. The two-planet arrangement provides an opportunity to probe the interior structure of HAT-P-13b. Under equilibrium-tide theory and confirmation that the apsides of planets b and c are in alignment, a measurement of the planet's eccentricity can be related to the planet's tidal Love number k2, which describes the central condensation of the planet's mass and its deformation under tidal effects. A measurement of k2 could constrain interior models of HAT-P-13b. HAT-P-13b's orbit is configured favorably for refinement of the eccentricity by secondary eclipse timing observations, which provide direct measurements of ecosω. In 2010, Spitzer observed two secondary eclipses of HAT-P-13b in the 3.6- and 4.5-μm IRAC bandpasses. We present secondary eclipse times and depths; joint models of the HAT-P-13 system that incorporate transit photometry and radial velocity data; and constraints on the atmospheric chemistry of HAT-P-13b that suggest solar-abundance composition without a thermal inversion. Spitzer is operated by the Jet Propulsion Laboratory, California Institute of Technology, under a contract with NASA, which provided support for this work. This work was supported in part by NASA Planetary Atmospheres Grant NNX13AF38G.

Constraints on the atmospheric circulation and variability of the eccentric hot Jupiter XO-3b

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wong, Ian; Knutson, Heather A.; Cowan, Nicolas B.

We report secondary eclipse photometry of the hot Jupiter XO-3b in the 4.5 μm band taken with the Infrared Array Camera on the Spitzer Space Telescope. We measure individual eclipse depths and center of eclipse times for a total of 12 secondary eclipses. We fit these data simultaneously with two transits observed in the same band in order to obtain a global best-fit secondary eclipse depth of 0.1580% ± 0.0036% and a center of eclipse phase of 0.67004 ± 0.00013. We assess the relative magnitude of variations in the dayside brightness of the planet by measuring the size of themore » residuals during ingress and egress from fitting the combined eclipse light curve with a uniform disk model and place an upper limit of 0.05%. The new secondary eclipse observations extend the total baseline from one and a half years to nearly three years, allowing us to place an upper limit on the periastron precession rate of 2.9 × 10{sup –3} deg day{sup –1}— the tightest constraint to date on the periastron precession rate of a hot Jupiter. We use the new transit observations to calculate improved estimates for the system properties, including an updated orbital ephemeris. We also use the large number of secondary eclipses to obtain the most stringent limits to date on the orbit-to-orbit variability of an eccentric hot Jupiter and demonstrate the consistency of multiple-epoch Spitzer observations.« less

Short gamma-ray bursts and gravitational-wave observations from eccentric compact binaries

NASA Astrophysics Data System (ADS)

Tan, Wei-Wei; Fan, Xi-Long; Wang, F. Y.

2018-03-01

Mergers of compact binaries, such as binary neutron stars (BNSs), neutron star-black hole binaries (NSBHs) and binary black holes (BBHs), are expected to be the best candidates for sources of gravitational waves (GWs) and the leading theoretical models for short gamma-ray bursts (SGRBs). Based on observations of SGRBs, we can derive the merger rates of these compact binaries and study stochastic GW backgrounds (SGWBs) or the co-detection rates of GWs associated with SGRBs (GW-SGRBs). Before that, however, the most important thing is to derive the GW spectrum from a single GW source. Usually, a GW spectrum from a circular-orbit binary is assumed. However, observations of the large spatial offsets of SGRBs from their host galaxies imply that SGRB progenitors may be formed by dynamical processes and will merge with residual eccentricities (er). The orbital eccentricity has an important effect on GW spectra and therefore on the SGWB and GW-SGRB co-detection rate. Our results show that the power spectra of SGWBs from eccentric compact binaries are greatly suppressed at low frequencies (e.g. f ≲ 1 Hz). In particular, SGWBs from binaries with high residual eccentricities (e.g. er ≳ 0.1 for BNSs) will be hard to detect (above the detection frequency of ˜ 100 Hz). Regarding the co-detection rates of GW-SGRB events, they could be ˜1.4 times higher than the circular case within some particular ranges of er (e.g. 0.01 ≲ er ≲ 0.1 for BBHs), but greatly reduced for high residual eccentricities (e.g. er > 0.1 for BNSs). In general, BBH progenitors produce 200 and 10 times higher GW-SGRB events than BNS and NSBH progenitors, respectively. Therefore, binaries with low residual eccentricities (e.g. 0.001 ≲ er ≲ 0.1) and high total masses will be easier to detect by Advanced LIGO (aLIGO). However, only a small fraction of BBHs can be SGRB progenitors (if they can produce SGRBs), because the predicted GW-SGRB event rate (60˜100 per year) is too high compared with recent observations, unless they merge with high residual eccentricities (e.g. er > 0.7).

Einstein observations of selected close binaries and shell stars

NASA Technical Reports Server (NTRS)

Guinan, E. F.; Koch, R. H.; Plavec, M. J.

1984-01-01

Several evolved close binaries and shell stars were observed with the IPC aboard the HEAO 2 Einstein Observatory. No eclipsing target was detected, and only two of the shell binaries were detected. It is argued that there is no substantial difference in L(X) for eclipsing and non-eclipsing binaries. The close binary and shell star CX Dra was detected as a moderately strong source, and the best interpretation is that the X-ray flux arises primarily from the corona of the cool member of the binary at about the level of Algol-like or RS CVn-type sources. The residual visible-band light curve of this binary has been modeled so as to conform as well as possible with this interpretation. HD 51480 was detected as a weak source. Substantial background information from IUE and ground scanner measurements are given for this binary. The positions and flux values of several accidentally detected sources are given.

Mass-Luminosity Relations for Rapid and Slow Rotators.

NASA Astrophysics Data System (ADS)

Malkov, O. Yu.

2006-08-01

Comparing the radii of eclipsing binaries components and single stars we have found a noticeable difference between observational parameters of B0V-G0V components of eclipsing binaries and those of single stars of the corresponding spectral type. This difference was confirmed by re-analysing the results of independent investigations published in the literature. Larger radii and higher temperatures of A-F eclipsing binaries can be explained by synchronization of such stars in close systems that prevents them to rotate rapidly. So, we have found that the mass-luminosity relation based on eclipsing binary data cannot be used to derive the initial mass function of single stars. While our current knowledge of the empirical mass-luminosity relation for intermediate-mass (1.5 to 10 m[*]) stars is based exclusively on data from eclipsing binaries, knowledge of the mass-luminosity relation should come from dynamical mass determinations of visual binaries, combined with spatially resolved precise photometry. Then the initial mass function should be revised for m>1.5m[*]. Data were collected on fundamental parameters of stars with masses m > 1.5.m [*]). They are components of binaries with P > 15^d and consequently are not synchronised with the orbital periods and presumably are rapid rotators. These stars are believed to evolve similarly with single stars, so these data allow us to construct mass-luminosity and other relations that can more confidently be used for statistical and astrophysical investigations of single stars than so called standard relations, based on data on detached main-sequence double-lined short-period eclipsing binaries. Mass-luminosity, mass-temperature and mass-radius relations of single stars are presented, as well as their HR diagram.

The 1982 ultraviolet eclipse of the symbiotic binary AR Pav

NASA Technical Reports Server (NTRS)

Hutchings, J. B.; Cowley, A. P.; Ake, T. B.; Imhoff, C. L.

1983-01-01

Observations with the International Ultraviolet Explorer (IUE) of the symbiotic binary AR Pav through its 1982 eclipse show that the hot star is not eclipsed. The hot star is associated with an extended region of continuum emission which is partially eclipsed. The eclipsed radiation is hotter near to its center, with a maximum temperature of about 9000 K. The uneclipsed flux is hotter than this. UV emission lines are not measurably eclipsed and presumably arise in a much larger region than the continuum. These data provide new constraints on models of the system but also are apparently in contradiction to those based on ground-based data.

Period analysis of the eclipsing binary AI Dra

NASA Astrophysics Data System (ADS)

Zasche, P.; Uhlář, R.; Svoboda, P.

2010-03-01

The eclipsing binary system AI Dra reveals changes of its orbital period. These variations could be described as a result of orbiting the eclipsing pair around a common center of mass with two unseen companions with the periods about 18 and 43 years together with a steady period increase. Fourteen new minima observations were carried out by the authors.

Absolute properties of the eclipsing binary VV CORVI

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fekel, Francis C.; Henry, Gregory W.; Sowell, James R., E-mail: fekel@evans.tsuniv.edu, E-mail: gregory.w.henry@gmail.com, E-mail: jim.sowell@physics.gatech.edu

2013-12-01

We have obtained red-wavelength spectroscopy and Johnson B and V differential photoelectric photometry of the eclipsing binary VV Crv = HR 4821. The system is the secondary of the common proper motion double star ADS 8627, which has a separation of 5.''2. VV Crv has an orbital period of 3.144536 days and a low but non-zero eccentricity of 0.085. With the Wilson-Devinney program we have determined a simultaneous solution of our spectroscopic and photometric observations. Those orbital elements produce masses of M {sub 1} = 1.978 ± 0.010 M {sub ☉} and M {sub 2} = 1.513 ± 0.008 Mmore » {sub ☉}, and radii of R {sub 1} = 3.375 ± 0.010 R {sub ☉} and R {sub 2} = 1.650 ± 0.008 R {sub ☉} for the primary and secondary, respectively. The effective temperatures of the two components are 6500 K (fixed) and 6638 K, so the star we call the primary is the more massive but cooler and larger component. A comparison with evolutionary tracks indicates that the components are metal rich with [Fe/H] = 0.3, and the system has an age of 1.2 Gyr. The primary is near the end of its main-sequence lifetime and is rotating significantly faster than its pseudosynchronous velocity. The secondary is still well ensconced on the main sequence and is rotating more slowly than its pseudosynchronous rate.« less

CCD Times of Minima of Selected Eclipsing Binaries

NASA Astrophysics Data System (ADS)

Zejda, Miloslav

2004-12-01

682 CCD minima observations of 259 eclipsing binaries made mainly by author are presented. The observed stars were chosen mainly from catalogue BRKA of observing programme of BRNO-Variable Star Section of CAS.

Eclipsing Binaries From the CSTAR Project at Dome A, Antarctica

NASA Astrophysics Data System (ADS)

Yang, Ming; Zhang, Hui; Wang, Songhu; Zhou, Ji-Lin; Zhou, Xu; Wang, Lingzhi; Wang, Lifan; Wittenmyer, R. A.; Liu, Hui-Gen; Meng, Zeyang; Ashley, M. C. B.; Storey, J. W. V.; Bayliss, D.; Tinney, Chris; Wang, Ying; Wu, Donghong; Liang, Ensi; Yu, Zhouyi; Fan, Zhou; Feng, Long-Long; Gong, Xuefei; Lawrence, J. S.; Liu, Qiang; Luong-Van, D. M.; Ma, Jun; Wu, Zhenyu; Yan, Jun; Yang, Huigen; Yang, Ji; Yuan, Xiangyan; Zhang, Tianmeng; Zhu, Zhenxi; Zou, Hu

2015-04-01

The Chinese Small Telescope ARray (CSTAR) has observed an area around the Celestial South Pole at Dome A since 2008. About 20,000 light curves in the i band were obtained during the observation season lasting from 2008 March to July. The photometric precision achieves about 4 mmag at i = 7.5 and 20 mmag at i = 12 within a 30 s exposure time. These light curves are analyzed using Lomb-Scargle, Phase Dispersion Minimization, and Box Least Squares methods to search for periodic signals. False positives may appear as a variable signature caused by contaminating stars and the observation mode of CSTAR. Therefore, the period and position of each variable candidate are checked to eliminate false positives. Eclipsing binaries are removed by visual inspection, frequency spectrum analysis, and a locally linear embedding technique. We identify 53 eclipsing binaries in the field of view of CSTAR, containing 24 detached binaries, 8 semi-detached binaries, 18 contact binaries, and 3 ellipsoidal variables. To derive the parameters of these binaries, we use the Eclipsing Binaries via Artificial Intelligence method. The primary and secondary eclipse timing variations (ETVs) for semi-detached and contact systems are analyzed. Correlated primary and secondary ETVs confirmed by false alarm tests may indicate an unseen perturbing companion. Through ETV analysis, we identify two triple systems (CSTAR J084612.64-883342.9 and CSTAR J220502.55-895206.7). The orbital parameters of the third body in CSTAR J220502.55-895206.7 are derived using a simple dynamical model.

DID THE ANCIENT EGYPTIANS RECORD THE PERIOD OF THE ECLIPSING BINARY ALGOL-THE RAGING ONE?

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jetsu, L.; Porceddu, S.; Lyytinen, J.

The eclipses in binary stars give precise information of orbital period changes. Goodricke discovered the 2.867 day period in the eclipses of Algol in the year 1783. The irregular orbital period changes of this longest known eclipsing binary continue to puzzle astronomers. The mass transfer between the two members of this binary should cause a long-term increase of the orbital period, but observations over two centuries have not confirmed this effect. Here, we present evidence indicating that the period of Algol was 2.850 days three millennia ago. For religious reasons, the ancient Egyptians have recorded this period into the Cairomore » Calendar (CC), which describes the repetitive changes of the Raging one. CC may be the oldest preserved historical document of the discovery of a variable star.« less

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

NASA Astrophysics Data System (ADS)

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 fidelity of Kepler eclipsing binary parameters inferred by the neural network

NASA Astrophysics Data System (ADS)

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

2018-07-01

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 detached eclipsing binaries 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 cosω and e sinω, but orbital inclination is clearly underestimated in neural network tests.

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

NASA Astrophysics Data System (ADS)

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.

The orbital eccentricities of binary millisecond pulsars in globular clusters

NASA Technical Reports Server (NTRS)

Rasio, Frederic A.; Heggie, Douglas C.

1995-01-01

Low-mass binary millisecond pulsars (LMBPs) are born with very small orbital eccentricities, typically of order e(sub i) approximately 10(exp -6) to 10(exp -3). In globular clusters, however, higher eccentricities e(sub f) much greater than e(sub i) can be induced by dynamical interactions with passing stars. Here we show that the cross section for this process is much larger than previously estimated. This is becuse, even for initially circular binaries, the induced eccentricity e(sub f) for an encounter with pericenter separation r(sub p) beyond a few times the binary semimajor axis a declines only as a power law (e(sub f) varies as (r(sub p)/a)(exp -5/2), and not as an exponential. We find that all currently known LMBPs in clusters were probably affected by interactions, with their current eccentricities typically greater than at birth by an order of magnitude or more.

The new eclipsing magnetic binary system E 1114 + 182

NASA Technical Reports Server (NTRS)

Biermann, P.; Schmidt, G. D.; Liebert, J.; Tapia, S.; Strittmatter, P. A.; West, S.; Stockman, H. S.; Kuehr, H.; Lamb, D. Q.

1985-01-01

A comprehensive analysis of E 1114 + 182, the first eclipsing AM Herculis binary system and the shortest-period eclipsing cataclysmic variable known, is presented. The time-resolved X-ray observations which led to the system's recognition as an AM Her system with a roughly 90 minute orbital period are reported. The current optical photometric and polarimetric ephemeris and a description of the system's phase-modulated properties are given. The detailed photometric eclipse profile and the highly variable spectroscopic behavior are addressed. This information is used to determine systemic parameters and derive new information on the line emission regions. The data put severe constraints on current torque models for keeping the binary and white dwarf rotation in phase.

From YY Boo (eclipsing binary) via J1407 (ringed companion) to WD 1145+017 (white dwarf with debris disk) (Abstract)

NASA Astrophysics Data System (ADS)

Hambsch, F.-J.

2018-06-01

(Abstract only) Several years ago by accident I observed YY Boo outside of an eclipse and was very surprised to see a short term periodic variation of about 0.1 mag. That was completely unexpected and it initiated an international campaign by amateurs to identify the cause of these variations. It turned out that YY Boo showed a pulsation period of about 88 min in addition to being an Algol type eclipsing binary. Hence it turned out that YY Boo has become a new member of a class of pulsating eclipsing binary systems with, at that time, the second largest amplitude after BO Her.

Ground-based detectability of terrestrial and Jovian extrasolar planets: observations of CM Draconis at Lick Observatory.

PubMed

Doyle, L R; Dunham, E T; Deeg, H J; Blue, J E; Jenkins, J M

1996-06-25

The detection of terrestrial-sized extrasolar planets from the ground has been thought to be virtually impossible due to atmospheric scintillation limits. However, we show that this is not the case especially selected (but nevertheless main sequence) stars, namely small eclipsing binaries. For the smallest of these systems, CM Draconis, several months to a few years of photometric observations with 1-m-class telescopes will be sufficient to detect the transits of any short-period planets of sizes > or = 1.5 Earth radii (RE), using cross-correlation analysis with moderately good photometry. Somewhat larger telescopes will be needed to extend this detectability to terrestrial planets in larger eclipsing binary systems. (We arbitrarily define "terrestrial planets" herein as those whose disc areas are closer to that of Earth's than Neptune's i.e., less than about 2.78 RE.) As a "spin-off" of such observations, we will also be able to detect the presence of Jovian-mass planets without transits using the timing of the eclipse minima. Eclipse minima will drift in time as the binary system is offset by a sufficiently massive planet (i.e., one Jupiter mass) about the binary/giant-planet barycenter, causing a periodic variation in the light travel time to the observer. We present here an outline of present observations taking place at the University of California Lick Observatory using the Crossley 0.9-m telescope in collaboration with other observatories (in South Korea, Crete, France, Canary Islands, and New York) to detect or constrain the existence of terrestrial planets around main sequence eclipsing binary star systems, starting with CM Draconis. We demonstrate the applicability of photometric data to the general detection of gas giant planets via eclipse minima timings in many other small-mass eclipsing binary systems as well.

Ground-based detectability of terrestrial and Jovian extrasolar planets: observations of CM Draconis at Lick Observatory

NASA Technical Reports Server (NTRS)

Doyle, L. R.; Dunham, E. T.; Deeg, H. J.; Blue, J. E.; Jenkins, J. M.

1996-01-01

The detection of terrestrial-sized extrasolar planets from the ground has been thought to be virtually impossible due to atmospheric scintillation limits. However, we show that this is not the case especially selected (but nevertheless main sequence) stars, namely small eclipsing binaries. For the smallest of these systems, CM Draconis, several months to a few years of photometric observations with 1-m-class telescopes will be sufficient to detect the transits of any short-period planets of sizes > or = 1.5 Earth radii (RE), using cross-correlation analysis with moderately good photometry. Somewhat larger telescopes will be needed to extend this detectability to terrestrial planets in larger eclipsing binary systems. (We arbitrarily define "terrestrial planets" herein as those whose disc areas are closer to that of Earth's than Neptune's i.e., less than about 2.78 RE.) As a "spin-off" of such observations, we will also be able to detect the presence of Jovian-mass planets without transits using the timing of the eclipse minima. Eclipse minima will drift in time as the binary system is offset by a sufficiently massive planet (i.e., one Jupiter mass) about the binary/giant-planet barycenter, causing a periodic variation in the light travel time to the observer. We present here an outline of present observations taking place at the University of California Lick Observatory using the Crossley 0.9-m telescope in collaboration with other observatories (in South Korea, Crete, France, Canary Islands, and New York) to detect or constrain the existence of terrestrial planets around main sequence eclipsing binary star systems, starting with CM Draconis. We demonstrate the applicability of photometric data to the general detection of gas giant planets via eclipse minima timings in many other small-mass eclipsing binary systems as well.

Search for A-F Spectral type pulsating components in Algol-type eclipsing binary systems

NASA Astrophysics Data System (ADS)

Kim, S.-L.; Lee, J. W.; Kwon, S.-G.; Youn, J.-H.; Mkrtichian, D. E.; Kim, C.

2003-07-01

We present the results of a systematic search for pulsating components in Algol-type eclipsing binary systems. A total number of 14 eclipsing binaries with A-F spectral type primary components were observed for 22 nights. We confirmed small-amplitude oscillating features of a recently detected pulsator TW Dra, which has a pulsating period of 0.053 day and a semi-amplitude of about 5 mmag in B-passband. We discovered new pulsating components in two eclipsing binaries of RX Hya and AB Per. The primary component of RX Hya is pulsating with a dominant period of 0.052 day and a semi-amplitude of about 7 mmag. AB Per has also a pulsating component with a period of 0.196 day and a semi-amplitude of about 10 mmag in B-passband. We suggest that these two new pulsators are members of the newly introduced group of mass-accreting pulsating stars in semi-detached Algol-type eclipsing binary systems. Table 4 is only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/405/231

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

NASA Astrophysics Data System (ADS)

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.

New Eclipsing Contact Binary System in Auriga

NASA Astrophysics Data System (ADS)

Austin, S. J.; Robertson, J. W.; Justice, C.; Campbell, R. T.; Hoskins, J.

2004-05-01

We present data on a newly discovered eclipsing binary system. The serendipitous discovery of this variable star was made by J.W. Robertson analyzing inhomogeneous ensemble photometry of stars in the field of the cataclysmic variable FS Aurigae from Indiana University RoboScope data. We obtained differential time-series BVR photometry during 2003 of this field variable using an ensemble of telescopes including the university observatories at ATU, UCA and joint ventures with amateur observatories in the state of Arkansas (Whispering Pines Observatory and Nubbin Ridge Observatory). The orbital period of this eclipsing system is 0.2508 days. The B-V light curve indicates colors of 1.2 around quadrature, to nearly 1.4 at primary eclipse. Binary star light curve models that best fit the BVR differential photometry suggest that the system is a contact binary overfilling the inner Roche Lobe by 12%, a primary component with a temperature of 4350K, a secondary component with a temperature of 3500K, a mass ratio of 0.37, and an inclination of 83 degrees. We present BVR light curves, an ephemeris, and best fit model parameters for the physical characteristics of this new eclipsing binary system.

Investigation of Times of Minima of Selected Early-Type Eclipsing Binaries

NASA Astrophysics Data System (ADS)

Mayer, Pavel; Wolf, Marek; Niarchos, P. G.; Gazeas, K. D.; Manimanis, V. N.; Chochol, Drahomír

2006-08-01

New precise times of minimum light for several early-type eclipsing binaries were obtained at three observatories. The changes of period of the following measured binaries are discussed: V1182 Aql, LY Aur, SZ Cam, FZ CMa, QZ Car, LZ Cen, V606 Cen, AH Cep and TU~Mus.

Indoor Astronomy: A Model Eclipsing Binary Star System.

ERIC Educational Resources Information Center

Bloomer, Raymond H., Jr.

1979-01-01

Describes a two-hour physics laboratory experiment modeling the phenomena of eclipsing binary stars developed by the Air Force Academy as part of a week-long laboratory-oriented experience for visiting high school students. (BT)

The Eclipsing Binary On-Line Atlas (EBOLA)

NASA Astrophysics Data System (ADS)

Bradstreet, D. H.; Steelman, D. P.; Sanders, S. J.; Hargis, J. R.

2004-05-01

In conjunction with the upcoming release of \\it Binary Maker 3.0, an extensive on-line database of eclipsing binaries is being made available. The purposes of the atlas are: \\begin {enumerate} Allow quick and easy access to information on published eclipsing binaries. Amass a consistent database of light and radial velocity curve solutions to aid in solving new systems. Provide invaluable querying capabilities on all of the parameters of the systems so that informative research can be quickly accomplished on a multitude of published results. Aid observers in establishing new observing programs based upon stars needing new light and/or radial velocity curves. Encourage workers to submit their published results so that others may have easy access to their work. Provide a vast but easily accessible storehouse of information on eclipsing binaries to accelerate the process of understanding analysis techniques and current work in the field. \\end {enumerate} The database will eventually consist of all published eclipsing binaries with light curve solutions. The following information and data will be supplied whenever available for each binary: original light curves in all bandpasses, original radial velocity observations, light curve parameters, RA and Dec, V-magnitudes, spectral types, color indices, periods, binary type, 3D representation of the system near quadrature, plots of the original light curves and synthetic models, plots of the radial velocity observations with theoretical models, and \\it Binary Maker 3.0 data files (parameter, light curve, radial velocity). The pertinent references for each star are also given with hyperlinks directly to the papers via the NASA Abstract website for downloading, if available. In addition the Atlas has extensive searching options so that workers can specifically search for binaries with specific characteristics. The website has more than 150 systems already uploaded. The URL for the site is http://ebola.eastern.edu/.

Photometric Analysis and Modeling of Five Mass-Transferring Binary Systems

NASA Astrophysics Data System (ADS)

Geist, Emily; Beaky, Matthew; Jamison, Kate

2018-01-01

In overcontact eclipsing binary systems, both stellar components have overfilled their Roche lobes, resulting in a dumbbell-shaped shared envelope. Mass transfer is common in overcontact binaries, which can be observed as a slow change on the rotation period of the system.We studied five overcontact eclipsing binary systems with evidence of period change, and thus likely mass transfer between the components, identified by Nelson (2014): V0579 Lyr, KN Vul, V0406 Lyr, V2240 Cyg, and MS Her. We used the 31-inch NURO telescope at Lowell Observatory in Flagstaff, Arizona to obtain images in B,V,R, and I filters for V0579 Lyr, and the 16-inch Meade LX200GPS telescope with attached SBIG ST-8XME CCD camera at Juniata College in Huntingdon, Pennsylvania to image KN Vul, V0406 Lyr, V2240 Cyg, and MS Her, also in B,V,R, and I.After data reduction, we created light curves for each of the systems and modeled the eclipsing binaries using the BinaryMaker3 and PHOEBE programs to determine their fundamental physical parameters for the first time. Complete light curves and preliminary models for each of these neglected eclipsing binary systems will be presented.

DEBCat: A Catalog of Detached Eclipsing Binary Stars

NASA Astrophysics Data System (ADS)

Southworth, J.

2015-07-01

Detached eclipsing binary star systems are our primary source of measured physical properties of normal stars. I introduce DEBCat: a catalog of detached eclipsing binaries with mass and radius measurements to the 2% precision necessary to put useful constraints on theoretical models of stellar evolution. The catalog was begun in 2006, as an update of the compilation by Andersen (1991). It now contains over 170 systems, and new results are added on appearance in the refereed literature. DEBCat is available at: http://www.astro.keele.ac.uk/jkt/debcat/.

Distinguishing Between Formation Channels for Binary Black Holes with LISA

NASA Astrophysics Data System (ADS)

Breivik, Katelyn; Rodriguez, Carl L.; Larson, Shane L.; Kalogera, Vassiliki; Rasio, Frederic A.

2017-01-01

The recent detections of GW150914 and GW151226 imply an abundance of stellar-mass binary-black-hole mergers in the local universe. While ground-based gravitational-wave detectors are limited to observing the final moments before a binary merges, space-based detectors, such as the Laser Interferometer Space Antenna (LISA), can observe binaries at lower orbital frequencies where such systems may still encode information about their formation histories. In particular, the orbital eccentricity and mass of binary black holes in the LISA frequency band can be used together to discriminate between binaries formed in isolation in galactic fields and those formed in dense stellar environments such as globular clusters. In this letter, we explore the orbital eccentricity and mass of binary-black-hole populations as they evolve through the LISA frequency band. Overall we find that there are two distinct populations discernible by LISA. We show that up to ~90% of binaries formed either dynamically or in isolation have eccentricities measurable by LISA. Finally, we note how measured eccentricities of low-mass binary black holes evolved in isolation could provide detailed constraints on the physics of black-hole natal kicks and common-envelope evolution.

A spectroscopic investigation of the eclipsing binary Epsilon Aurigae

NASA Technical Reports Server (NTRS)

Balachandran, Suchitra

1991-01-01

The objectives were to examine, in detail, the spectra of the eclipsing binary Epsilon Aurigae taken with the IUE satellite telescope during the 1982 to 1984 eclipse. All of the low resolution spectra were analyzed and UV light curves are presented. The primary findings are as follows: (1) a constant eclipse depth from 1600 A to longer wavelengths and a sharp drop in the eclipse depth from 1600 to 1200 A; (2) the absence of large amplitude fluctuations in the UV as expected from a Cepheid primary; and (3) equal ingress and egress times in contradiction to that interpreted from visible light curves. The effects of these findings on the eclipse geometry are being studied.

Accuracy of Estimating Highly Eccentric Binary Black Hole Parameters with Gravitational-wave Detections

NASA Astrophysics Data System (ADS)

Gondán, László; Kocsis, Bence; Raffai, Péter; Frei, Zsolt

2018-03-01

Mergers of stellar-mass black holes on highly eccentric orbits are among the targets for ground-based gravitational-wave detectors, including LIGO, VIRGO, and KAGRA. These sources may commonly form through gravitational-wave emission in high-velocity dispersion systems or through the secular Kozai–Lidov mechanism in triple systems. Gravitational waves carry information about the binaries’ orbital parameters and source location. Using the Fisher matrix technique, we determine the measurement accuracy with which the LIGO–VIRGO–KAGRA network could measure the source parameters of eccentric binaries using a matched filtering search of the repeated burst and eccentric inspiral phases of the waveform. We account for general relativistic precession and the evolution of the orbital eccentricity and frequency during the inspiral. We find that the signal-to-noise ratio and the parameter measurement accuracy may be significantly higher for eccentric sources than for circular sources. This increase is sensitive to the initial pericenter distance, the initial eccentricity, and the component masses. For instance, compared to a 30 {M}ȯ –30 {M}ȯ non-spinning circular binary, the chirp mass and sky-localization accuracy can improve by a factor of ∼129 (38) and ∼2 (11) for an initially highly eccentric binary assuming an initial pericenter distance of 20 M tot (10 M tot).

CCD Times of Minima of Faint Eclipsing Binaries in 2000

NASA Astrophysics Data System (ADS)

Zejda, Miloslav

2002-06-01

196 CCD minima observations of 122 eclipsing binaries made by the author in 2000 are presented. The observed stars were chosen from the catalogue BRKA of observing programme of BRNO-Variable Star Section of CAS.

Observations, Roche Lobe Analysis, and Period Study of the Eclipsing Contact Binary System GM Canum Venaticorum

NASA Astrophysics Data System (ADS)

Alton, K. B.; Nelson, R. H.

2018-06-01

GM CVn is an eclipsing W UMa binary system (P = 0.366984 d) which has been largely neglected since its variability was first detected during the ROTSE campaign (1999-2000). Other than a single unfiltered light curve (LC) no other photometric data have been published. LC data collected in three bandpasses (B, V, and Rc) at UnderOak Observatory (UO) produced three new times of minimum for GM CVn. These along with other eclipse timings from the literature were used to update the linear ephemeris. Roche modeling to produce synthetic LC fits to the observed data was accomplished using binary maker 3, wdwint56a, and phoebe v.31a. Newly acquired radial velocity data were pivotal to defining the absolute and geometric parameters for this partially eclipsing binary system. An unspotted solution achieved the best Roche model fits for the multi-color LCs collected in 2013.

Eccentric binaries - still interesting targets

NASA Astrophysics Data System (ADS)

Zasche, P.

2018-04-01

Eccentric binaries still provides us with valuable results and new observations of these systems are welcome. Especially these ones never analysed before should be observed for their light curves and minima.

Searching for planets around eclipsing binary stars using timing method: NSVS 14256825

NASA Astrophysics Data System (ADS)

Nasiroglu, Ilham; Goździewski, Krzysztof; Słowikowska, Aga; Krzeszowski, Krzysztof; Żejmo, Michal; Zola, Staszek; Er, Huseyin

2018-04-01

We present four new mid eclipse times and an updated O-C diagram of the short period eclipsing binary NSVS14256825. The new data follow the (O-C) trend and its model proposed in Nasiroglu et al. (2017). The (O-C) diagram shows quasi-periodic variations that can be explained with the presence of a brown-dwarf in a quasi-circular circumbinary orbit.

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

NASA Astrophysics Data System (ADS)

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.

Reducing orbital eccentricity of precessing black-hole binaries

DOE Office of Scientific and Technical Information (OSTI.GOV)

Buonanno, Alessandra; Taracchini, Andrea; Kidder, Lawrence E.

2011-05-15

Building initial conditions for generic binary black-hole evolutions which are not affected by initial spurious eccentricity remains a challenge for numerical-relativity simulations. This problem can be overcome by applying an eccentricity-removal procedure which consists of evolving the binary black hole for a couple of orbits, estimating the resulting eccentricity, and then restarting the simulation with corrected initial conditions. The presence of spins can complicate this procedure. As predicted by post-Newtonian theory, spin-spin interactions and precession prevent the binary from moving along an adiabatic sequence of spherical orbits, inducing oscillations in the radial separation and in the orbital frequency. For single-spinmore » binary black holes these oscillations are a direct consequence of monopole-quadrupole interactions. However, spin-induced oscillations occur at approximately twice the orbital frequency, and therefore can be distinguished and disentangled from the initial spurious eccentricity which occurs at approximately the orbital frequency. Taking this into account, we develop a new eccentricity-removal procedure based on the derivative of the orbital frequency and find that it is rather successful in reducing the eccentricity measured in the orbital frequency to values less than 10{sup -4} when moderate spins are present. We test this new procedure using numerical-relativity simulations of binary black holes with mass ratios 1.5 and 3, spin magnitude 0.5, and various spin orientations. The numerical simulations exhibit spin-induced oscillations in the dynamics at approximately twice the orbital frequency. Oscillations of similar frequency are also visible in the gravitational-wave phase and frequency of the dominant l=2, m=2 mode.« less

Searching Planets Around Some Selected Eclipsing Close Binary Stars Systems

NASA Astrophysics Data System (ADS)

Nasiroglu, Ilham; Slowikowska, Agnieszka; Krzeszowski, Krzysztof; Zejmo, M. Michal; Er, Hüseyin; Goździewski, Krzysztof; Zola, Stanislaw; Koziel-Wierzbowska, Dorota; Debski, Bartholomew; Ogloza, Waldemar; Drozdz, Marek

2016-07-01

We present updated O-C diagrams of selected short period eclipsing binaries observed since 2009 with the T100 Telescope at the TUBITAK National Observatory (Antalya, Turkey), the T60 Telescope at the Adiyaman University Observatory (Adiyaman, Turkey), the 60cm at the Mt. Suhora Observatory of the Pedagogical University (Poland) and the 50cm Cassegrain telescope at the Fort Skala Astronomical Observatory of the Jagiellonian University in Krakow, Poland. All four telescopes are equipped with sensitive, back-illuminated CCD cameras and sets of wide band filters. One of the targets in our sample is a post-common envelope eclipsing binary NSVS 14256825. We collected more than 50 new eclipses for this system that together with the literature data gives more than 120 eclipse timings over the time span of 8.5 years. The obtained O-C diagram shows quasi-periodic variations that can be well explained by the existence of the third body on Jupiter-like orbit. We also present new results indicating a possible light time travel effect inferred from the O-C diagrams of two other binary systems: HU Aqr and V470 Cam.

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

NASA Astrophysics Data System (ADS)

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.

Double-lined M dwarf eclipsing binaries from Catalina Sky Survey and LAMOST

NASA Astrophysics Data System (ADS)

Lee, Chien-Hsiu; Lin, Chien-Cheng

2017-02-01

Eclipsing binaries provide a unique opportunity to determine fundamental stellar properties. In the era of wide-field cameras and all-sky imaging surveys, thousands of eclipsing binaries have been reported through light curve classification, yet their basic properties remain unexplored due to the extensive efforts needed to follow them up spectroscopically. In this paper we investigate three M2-M3 type double-lined eclipsing binaries discovered by cross-matching eclipsing binaries from the Catalina Sky Survey with spectroscopically classified M dwarfs from the Large Sky Area Multi-Object Fiber Spectroscopic Telescope survey data release one and two. Because these three M dwarf binaries are faint, we further acquire radial velocity measurements using GMOS on the Gemini North telescope with R˜ 4000, enabling us to determine the mass and radius of individual stellar components. By jointly fitting the light and radial velocity curves of these systems, we derive the mass and radius of the primary and secondary components of these three systems, in the range between 0.28-0.42M_⊙ and 0.29-0.67R_⊙, respectively. Future observations with a high resolution spectrograph will help us pin down the uncertainties in their stellar parameters, and render these systems benchmarks to study M dwarfs, providing inputs to improving stellar models in the low mass regime, or establishing an empirical mass-radius relation for M dwarf stars.

Recent Minima of 171 Eclipsing Binary Stars

NASA Astrophysics Data System (ADS)

Samolyk, G.

2015-12-01

This paper continues the publication of times of minima for 171 eclipsing binary stars from observations reported to the AAVSO EB section. Times of minima from observations received by the author from March 2015 thru October 2015 are presented.

Using LISA to Learn How Pairs of Black Holes Formed

NASA Astrophysics Data System (ADS)

Kohler, Susanna

2016-11-01

Artists impression of the European Space Agencys Laser Interferometer Space Antenna, currently planned for a 2034 launch. [NASA]How are black-hole binaries built? Observations of gravitational waves from these systems made using the European Space Agencys upcoming mission, the Laser Interferometer Space Antenna (LISA) may be able to reveal their origins.Formation ChannelsThere are two primary placeswhere stellar-mass black-hole binaries are thought to form:In isolation in the galactic field, as the components of a stellar binary independently evolve into black holes but remain bound to each other.In dense stellar environments like globular clusters, where the high density of already-formed black holes can cause a pair to dynamically interact and form a binary before being ejected from the cluster.Can we differentiate between these origins based on future detections of gravitational waves from black-hole binaries? A team of scientists led by Katelyn Breivik (CIERA, Northwestern University) thinks that we can!The gravitational-wave spectrum and how we detect it (click for a closer look!). While ground-based interferometers like LIGO detect black-hole binaries in the final moments before merger, LISAs lower frequency band will allow it to detect binaries earlier in their inspiral. [NASA Goddard SFC]Differentiation by EccentricityBreivik and collaborators believe that the key clue is the binarys eccentricity. Gravitational-wave emission will eventually circularize all black-hole binaries during their inspiral. But in the first formation scenario, binary evolution processes like tidal circularization and mass transfer will reduce the binarys eccentricity early on whereas in the second scenario, the binaries that form in globular clusters may retain eccentricity in their orbits long enough that we can detect it.Ground-based interferometers wont be up to this task; by the time the binary orbits shrink enough to evolve into the LIGO frequency band, the orbits wont have measurable eccentricity anymore. But the upcoming space-based LISA mission, which will operate in a lower frequency band, might be able to pick up this signature.To determine if LISA can pull it off, Breivik and collaborators simulate two populations of binary black holes: one evolved in isolation in galactic fields, and the other formed dynamically in globular clusters and then ejected. The authors then explore the evolution of these populations masses and eccentricities as their orbits narrow into the LISA-detectable frequency band.Eccentricity evolution tracks as a function of gravitational-wave frequency for black-hole binaries formed in dynamical scenarios (black) and in isolation (blue for those with a common-envelope episode, green for those without). Eccentricities above 10-2 are measurable for all binaries; those above 10-3 are measurable for 90%. LISAs frequency band is shown in grey. [Breivik et al. 2016]Separating PopulationsBreivik and collaborators find that LISA will be able to make several important distinctions. First, if LISA detects binary black holes with eccentricities of e 0.01 at frequencies above 10-2 Hz, we can be fairly certainthat these originated from dynamical processes in dense stellar environments.For binary black holes detected with eccentricities of e 0.01 at lower frequencies, they could either have formed in dense stellar environments or they could have formed in isolation. Based on this studys results, however, those with measurable eccentricities that formed in isolation mostlikely originated from a common-envelope formation. Measuring eccentricities of such systems in the future could provide constraints on the physics of how this formation mechanism works.Though the field of gravitational-wave astronomy is only just beginning, its future is promising! Theoretical studies like this one will help us to extracta greater understanding from the observations we can expect down the road.BonusCheck out this beautiful simulationfrom Northwestern Visualization and Carl Rodriguez (a co-author on the above study) that shows what the formation of a binary black hole in a globular cluster might look like!http://aasnova.org/wp-content/uploads/2016/11/accelerated_nbody_hd.mp4CitationKatelyn Breivik et al 2016 ApJL 830 L18. doi:10.3847/2041-8205/830/1/L18

Complete waveform model for compact binaries on eccentric orbits

NASA Astrophysics Data System (ADS)

Huerta, E. A.; Kumar, Prayush; Agarwal, Bhanu; George, Daniel; Schive, Hsi-Yu; Pfeiffer, Harald P.; Haas, Roland; Ren, Wei; Chu, Tony; Boyle, Michael; Hemberger, Daniel A.; Kidder, Lawrence E.; Scheel, Mark A.; Szilagyi, Bela

2017-01-01

We present a time domain waveform model that describes the inspiral, merger and ringdown of compact binary systems whose components are nonspinning, and which evolve on orbits with low to moderate eccentricity. The inspiral evolution is described using third-order post-Newtonian equations both for the equations of motion of the binary, and its far-zone radiation field. This latter component also includes instantaneous, tails and tails-of-tails contributions, and a contribution due to nonlinear memory. This framework reduces to the post-Newtonian approximant TaylorT4 at third post-Newtonian order in the zero-eccentricity limit. To improve phase accuracy, we also incorporate higher-order post-Newtonian corrections for the energy flux of quasicircular binaries and gravitational self-force corrections to the binding energy of compact binaries. This enhanced prescription for the inspiral evolution is combined with a fully analytical prescription for the merger-ringdown evolution constructed using a catalog of numerical relativity simulations. We show that this inspiral-merger-ringdown waveform model reproduces the effective-one-body model of Ref. [Y. Pan et al., Phys. Rev. D 89, 061501 (2014)., 10.1103/PhysRevD.89.061501] for quasicircular black hole binaries with mass ratios between 1 to 15 in the zero-eccentricity limit over a wide range of the parameter space under consideration. Using a set of eccentric numerical relativity simulations, not used during calibration, we show that our new eccentric model reproduces the true features of eccentric compact binary coalescence throughout merger. We use this model to show that the gravitational-wave transients GW150914 and GW151226 can be effectively recovered with template banks of quasicircular, spin-aligned waveforms if the eccentricity e0 of these systems when they enter the aLIGO band at a gravitational-wave frequency of 14 Hz satisfies e0GW 150914≤0.15 and e0GW 151226≤0.1 . We also find that varying the spin combinations of the quasicircular, spin-aligned template waveforms does not improve the recovery of nonspinning, eccentric signals when e0≥0.1 . This suggests that these two signal manifolds are predominantly orthogonal.

International Ultraviolet Explorer observations of the peculiar variable spectrum of the eclipsing binary R Arae

NASA Technical Reports Server (NTRS)

Mccluskey, G. E.; Kondo, Y.

1983-01-01

The eclipsing binary system R Arae = HD 149730 is a relatively bright southern system with an orbital period of about 4.4 days. It is a single-lined spectroscopic binary. The spectral class of the primary component is B9 Vp. The system was included in a study of mass flow and evolution in close binary systems using the International Ultraviolet Explorer satellite (IUE). Four spectra in the wavelength range from 1150 to 1900 A were obtained with the far-ultraviolet SWP camera, and six spectra in the range from 1900 to 3200 range were obtained with the mid-ultraviolet LWR camera. The close binary R Arae exhibits very unusual ultraviolet spectra. It appears that no other close binary system, observed with any of the orbiting satellites, shows outside-eclipse ultraviolet continuum flux variations of this nature.

Dynamics of binary-disk interaction. 1: Resonances and disk gap sizes

NASA Technical Reports Server (NTRS)

Artymowicz, Pawel; Lubow, Stephen H.

1994-01-01

We investigate the gravitational interaction of a generally eccentric binary star system with circumbinary and circumstellar gaseous disks. The disks are assumed to be coplanar with the binary, geometrically thin, and primarily governed by gas pressure and (turbulent) viscosity but not self-gravity. Both ordinary and eccentric Lindblad resonances are primarily responsible for truncating the disks in binaries with arbitrary eccentricity and nonextreme mass ratio. Starting from a smooth disk configuration, after the gravitational field of the binary truncates the disk on the dynamical timescale, a quasi-equilibrium is achieved, in which the resonant and viscous torques balance each other and any changes in the structure of the disk (e.g., due to global viscous evolution) occur slowly, preserving the average size of the gap. We analytically compute the approximate sizes of disks (or disk gaps) as a function of binary mass ratio and eccentricity in this quasi-equilibrium. Comparing the gap sizes with results of direct simulations using the smoothed particle hydrodynamics (SPH), we obtain a good agreement. As a by-product of the computations, we verify that standard SPH codes can adequately represent the dynamics of disks with moderate viscosity, Reynolds number R approximately 10(exp 3). For typical viscous disk parameters, and with a denoting the binary semimajor axis, the inner edge location of a circumbinary disk varies from 1.8a to 2.6a with binary eccentricity increasing from 0 to 0.25. For eccentricities 0 less than e less than 0.75, the minimum separation between a component star and the circumbinary disk inner edge is greater than a. Our calculations are relevant, among others, to protobinary stars and the recently discovered T Tau pre-main-sequence binaries. We briefly examine the case of a pre-main-sequence spectroscopic binary GW Ori and conclude that circumbinary disk truncation to the size required by one proposed spectroscopic model cannot be due to Linblad resonances, even if the disk is nonviscous.

THE BANANA PROJECT. III. SPIN-ORBIT ALIGNMENT IN THE LONG-PERIOD ECLIPSING BINARY NY CEPHEI

DOE Office of Scientific and Technical Information (OSTI.GOV)

Albrecht, Simon; Winn, Joshua N.; Carter, Joshua A.

Binaries are not always neatly aligned. Previous observations of the DI Her system showed that the spin axes of both stars are highly inclined with respect to one another and the orbital axis. Here, we report on a measurement of the spin-axis orientation of the primary star of the NY Cep system, which is similar to DI Her in many respects: it features two young early-type stars ({approx}6 Myr, B0.5V+B2V), in an eccentric and relatively long-period orbit (e = 0.48, P = 15fd3). The sky projections of the rotation vector and the spin vector are well aligned ({beta}{sub p} =more » 2{sup 0} {+-} 4{sup 0}), in strong contrast to DI Her. Although no convincing explanation has yet been given for the misalignment of DI Her, our results show that the phenomenon is not universal, and that a successful theory will need to account for the different outcome in the case of NY Cep.« less

Spectroscopic obit for the eclipsing binary IQ Persei

DOE Office of Scientific and Technical Information (OSTI.GOV)

Young, A.

1975-10-01

Spectroscopic orbital elements are derived for the eclipsing binary IQ Per. Faint secondary lines are detected, and a mass ratio and individual masses are inferred. The components are found to be on the main sequence, and the system is detached. (auth)

Analysis of Pulsating Components in the Eclipsing Binary Systems LT Herculis, RZ Microscopii, LY Puppis, V632 Scorpii, and V638 Scorpii

NASA Astrophysics Data System (ADS)

Streamer, M.; Bohlsen, T.; Ogmen, Y.

2016-06-01

Eclipsing binary stars are especially valuable for studies of stellar evolution. If pulsating components are also present then the stellar interior can be studied using asteroseismology techniques. We present photometric data and the analysis of the delta Scuti pulsations that we have discovered in five eclipsing binary systems. The systems are: LT Herculis, RZ Microscopii, LY Puppis, V632 Scorpii and V638 Scorpii. The dominant pulsation frequencies range between 13 - 29 cycles per day with semi-amplitudes of 4 - 20 millimagnitudes.

New O-C Observations for 150 Algols: Insight to the Origins of Period Shifts

NASA Astrophysics Data System (ADS)

Hoffman, D. I.; Harrison, T. E.; McNamara, B. J.; Vestrand, W. T.

2005-12-01

Many eclipsing binaries of type Algol, RS CVn, and W UMa have observed orbital period shifts. Of these, many show both increasing and decreasing period shifts. Two leading explanations for these shifts are third body effects and magnetic activity changing the oblateness of the secondary, though neither one can explain all of the observed period oscillations. The first-generation Robotic Optical Transient Search Experiment (ROTSE-I) based in Los Alamos, NM, was primarily designed to look for the optical counterparts to gamma-ray bursts as well as searching for other optical transients not detected in gamma-rays. The telescope, consisting of four 200mm camera lenses, can image the entire northern sky twice in a night, which is a very useful tool in monitoring relatively bright eclipsing binaries for period shifts. The public data release from ROTSE-I, the Northern Sky Variability Survey (NSVS), spans one year of data stating in April, 1999. O-C data for 150 eclipsing binaries are presented using the NSVS data. We revisit work by Borkovits and Hegedüs on some third body candidates in several eclipsing binary systems using recent AAVSO and NSVS data. Some unusual light curves of eclipsing binaries produced from NSVS data is presented and discussed.

Binarity and Variable Stars in the Open Cluster NGC 2126

NASA Astrophysics Data System (ADS)

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.

A New Orbit for the Eclipsing Binary V577 Oph

DOE Office of Scientific and Technical Information (OSTI.GOV)

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

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 velocitymore » 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.« less

HAT-TR-318-007: A Double-lined M Dwarf Binary with Total Secondary Eclipses Discovered by HATNet and Observed by K2

NASA Astrophysics Data System (ADS)

Hartman, J. D.; Quinn, S. N.; Bakos, G. Á.; Torres, G.; Kovács, G.; Latham, D. W.; Noyes, R. W.; Shporer, A.; Fulton, B. J.; Esquerdo, G. A.; Everett, M. E.; Penev, K.; Bhatti, W.; Csubry, Z.

2018-03-01

We report the discovery by the HATNet survey of HAT-TR-318-007, a P=3.34395390+/- 0.00000020 day period detached double-lined M dwarf binary with total secondary eclipses. We combine radial velocity (RV) measurements from TRES/FLWO 1.5 m and time-series photometry from HATNet, FLWO 1.2 m, BOS 0.8 m, and NASA K2 Campaign 5, to determine the masses and radii of the component stars: MA=0.448+/-0.011 M⊙N, MB=0.2721-0.0042+0.0041 M⊙N, RA=0.4548-0.0036+0.0035 R⊙N, and RB=0.2913-0.0024+0.0023 R⊙N. We obtained a FIRE/Magellan near-infrared spectrum of the primary star during a total secondary eclipse, and we use this to obtain disentangled spectra of both components. We determine spectral types of STA=M 3.71+/- 0.69 and STB=M 5.01+/- 0.73 and effective temperatures of Teff, A= 3190+/-110 K and Teff, B=3100+/- 110 K for the primary and secondary star, respectively. We also measure a metallicity of [Fe/H] = +0.298+/- 0.080 for the system. We find that the system has a small, but significant, nonzero eccentricity of 0.0136+/- 0.0026. The K2 light curve shows a coherent variation at a period of 3.41315-0.00032+0.00030 days, which is slightly longer than the orbital period, and which we demonstrate comes from the primary star. We interpret this as the rotation period of the primary. We perform a quantitative comparison between the Dartmouth stellar evolution models and the seven systems, including HAT-TR-318-007, that contain M dwarfs with 0.2 M⊙N< M< 0.5 M⊙N, have metallicity measurements, and have masses and radii determined to better than 5% precision. Discrepancies between the predicted and observed masses and radii are found for three of the systems.

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

NASA Astrophysics Data System (ADS)

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.

The Eclipsing Central Stars of the Planetary Nebulae Lo 16 and PHR J1040-5417

NASA Astrophysics Data System (ADS)

Hillwig, Todd C.; Frew, David; Jones, David; Crispo, Danielle

2017-01-01

Binary central stars of planetary nebula are a valuable tool in understanding common envelope evolution. In these cases both the resulting close binary system and the expanding envelope (the planetary nebula) can be studied directly. In order to compare observed systems with common envelope evolution models we need to determine precise physical parameters of the binaries and the nebulae. Eclipsing central stars provide us with the best opportunity to determine high precision values for mass, radius, and temperature of the component stars in these close binaries. We present photometry and spectroscopy for two of these eclipsing systems; the central stars of Lo 16 and PHR 1040-5417. Using light curves and radial velocity curves along with binary modeling we provide physical parameters for the stars in both of these systems.

State-change in the "transition" binary millisecond pulsar J1023+0038

NASA Astrophysics Data System (ADS)

Stappers, B. W.; Archibald, A.; Bassa, C.; Hessels, J.; Janssen, G.; Kaspi, V.; Lyne, A.; Patruno, A.; Hill, A. B.

2013-10-01

We report a change in the state of PSR J1023+0038, a source which is believed to be transitioning from an X-ray binary to an eclipsing binary radio millisecond pulsar (Archibald et al. 2009, Science, 324, 1411). The system was known to contain an accretion disk in 2001 but has shown no signs of it, or of accretion, since then, rather exhibiting all the properties of an eclipsing binary millisecond radio pulsar (MSP).

The Age and Distance of the Kepler Open Cluster NGC 6811 from an Eclipsing Binary, Turnoff Star Pulsation, and Giant Asteroseismology

NASA Astrophysics Data System (ADS)

Sandquist, Eric L.; Jessen-Hansen, J.; Shetrone, Matthew D.; Brogaard, Karsten; Meibom, Søren; Leitner, Marika; Stello, Dennis; Bruntt, Hans; Antoci, Victoria; Orosz, Jerome A.; Grundahl, Frank; Frandsen, Søren

2016-11-01

We present the analysis of an eccentric, partially eclipsing long-period (P = 19.23 days) binary system KIC 9777062 that contains main-sequence stars near the turnoff of the intermediate-age open cluster NGC 6811. The primary is a metal-lined Am star with a possible convective blueshift to its radial velocities, and one star (probably the secondary) is likely to be a γ Dor pulsator. The component masses are 1.603 ± 0.006(stat.) ± 0.016(sys.) and 1.419 ± 0.003 ± 0.008 {M}⊙ , and the radii are 1.744 ± 0.004 ± 0.002 and 1.544 ± 0.002 ± 0.002 {R}⊙ . The isochrone ages of the stars are mildly inconsistent: the age from the mass-radius combination for the primary (1.05 ± 0.05 ± 0.09 Gyr, where the last quote was systematic uncertainty from models and metallicity) is smaller than that from the secondary (1.21 ± 0.05 ± 0.15 Gyr) and is consistent with the inference from the color-magnitude diagram (1.00 ± 0.05 Gyr). We have improved the measurements of the asteroseismic parameters Δν and ν max for helium-burning stars in the cluster. The masses of the stars appear to be larger (or alternately, the radii appear to be smaller) than predicted from isochrones using the ages derived from the eclipsing stars. The majority of stars near the cluster turnoff are pulsating stars: we identify a sample of 28 δ Sct, 15 γ Dor, and 5 hybrid types. We used the period-luminosity relation for high-amplitude δ Sct stars to fit the ensemble of the strongest frequencies for the cluster members, finding {(m-M)}V=10.37+/- 0.03. This is larger than most previous determinations, but smaller than values derived from the eclipsing binary (10.47 ± 0.05). Based on observations made with the Hobby-Eberly Telescope, which is a joint project of the University of Texas at Austin, the Pennsylvania State University, Stanford University, Ludwig-Maximilians-Universität München, and Georg-August-Universität Göttingen, and with the Nordic Optical Telescope, operated by the Nordic Optical Telescope Scientific Association at the Observatorio del Roque de los Muchachos, La Palma, Spain, of the Instituto de Astrofisica de Canarias.

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

NASA Astrophysics Data System (ADS)

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.

The massive multiple system HD 64315

NASA Astrophysics Data System (ADS)

Lorenzo, J.; Simón-Díaz, S.; Negueruela, I.; Vilardell, F.; Garcia, M.; Evans, C. J.; Montes, D.

2017-10-01

Context. The O6 Vn star HD 64315 is believed to belong to the star-forming region known as NGC 2467, but previous distance estimates do not support this association. Moreover, it has been identified as a spectroscopic binary, but existing data support contradictory values for its orbital period. Aims: We explore the multiple nature of this star with the aim of determining its distance, and understanding its connection to NGC 2467. Methods: A total of 52 high-resolution spectra have been gathered over a decade. We use their analysis, in combination with the photometric data from All Sky Automated Survey and Hipparcos catalogues, to conclude that HD 64315 is composed of at least two spectroscopic binaries, one of which is an eclipsing binary. We have developed our own program to fit four components to the combined line shapes. Once the four radial velocities were derived, we obtained a model to fit the radial-velocity curves using the Spectroscopic Binary Orbit Program (SBOP). We then implemented the radial velocities of the eclipsing binary and the light curves in the Wilson-Devinney code iteratively to derive stellar parameters for its components. We were also able to analyse the non-eclipsing binary, and to derive minimum masses for its components which dominate the system flux. Results: HD 64315 contains two binary systems, one of which is an eclipsing binary. The two binaries are separated by 0.09 arcsec (or 500 AU) if the most likely distance to the system, 5 kpc, is considered. The presence of fainter companions is not excluded by current observations. The non-eclipsing binary (HD 64315 AaAb) has a period of 2.70962901 ± 0.00000021 d. Its components are hotter than those of the eclipsing binary, and dominate the appearance of the system. The eclipsing binary (HD 64315 BaBb) has a shorter period of 1.0189569 ± 0.0000008 d. We derive masses of 14.6 ± 2.3 M⊙ for both components of the BaBb system. They are almost identical; both stars are overfilling their respective Roche lobes, and share a common envelope in an overcontact configuration. The non-eclipsing binary is a detached system composed of two stars with spectral types around O6 V with minimum masses of 10.8 M⊙ and 10.2 M⊙, and likely masses ≈ 30 M⊙. Conclusions: HD 64315 provides a cautionary tale about high-mass star isolation and multiplicity. Its total mass is likely above 90M⊙, but it seems to have formed without an accompanying cluster. It contains one the most massive overcontact binaries known, a likely merger progenitor in a very wide multiple system. Based on observations obtained at the European Southern Observatory under programmes 078.D-0665(A), 082-D.0136 and 093.A-9001(A). Based on observations made with the Nordic Optical Telescope, operated on the island of La Palma jointly by Denmark, Finland, Iceland, Norway, and Sweden, in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofísica de Canarias.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Prsa, Andrej; Engle, Scott G.; Conroy, Kyle

2011-03-15

The Kepler space mission is devoted to finding Earth-size planets orbiting other stars in their habitable zones. Its large, 105 deg{sup 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),more » ephemeris (BJD{sub 0}, P{sub 0}), morphology type, physical parameters (T{sub eff}, log g, E(B - V)), the estimate of third light contamination (crowding), and principal parameters (T{sub 2}/T{sub 1}, q, fillout factor, and sin i for overcontacts, and T{sub 2}/T{sub 1}, (R{sub 1} + R{sub 2})/a, esin {omega}, ecos {omega}, 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 {approx}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.« less

Towards a Fundamental Understanding of Short Period Eclipsing Binary Systems Using Kepler Data

NASA Astrophysics Data System (ADS)

Prsa, Andrej

Kepler's ultra-high precision photometry is revolutionizing stellar astrophysics. We are seeing intrinsic phenomena on an unprecedented scale, and interpreting them is both a challenge and an exciting privilege. Eclipsing binary stars are of particular significance for stellar astrophysics because precise modeling leads to fundamental parameters of the orbiting components: masses, radii, temperatures and luminosities to better than 1-2%. On top of that, eclipsing binaries are ideal physical laboratories for studying other physical phenomena, such as asteroseismic properties, chromospheric activity, proximity effects, mass transfer in close binaries, etc. Because of the eclipses, the basic geometry is well constrained, but a follow-up spectroscopy is required to get the dynamical masses and the absolute scale of the system. A conjunction of Kepler photometry and ground- based spectroscopy is a treasure trove for eclipsing binary star astrophysics. This proposal focuses on a carefully selected set of 100 short period eclipsing binary stars. The fundamental goal of the project is to study the intrinsic astrophysical effects typical of short period binaries in great detail, utilizing Kepler photometry and follow-up spectroscopy to devise a robust and consistent set of modeling results. The complementing spectroscopy is being secured from 3 approved and fully funded programs: the NOAO 4-m echelle spectroscopy at Kitt Peak (30 nights; PI Prsa), the 10- m Hobby-Eberly Telescope high-resolution spectroscopy (PI Mahadevan), and the 2.5-m Sloan Digital Sky Survey III spectroscopy (PI Mahadevan). The targets are prioritized by the projected scientific yield. Short period detached binaries host low-mass (K- and M- type) components for which the mass-radius relationship is sparsely populated and still poorly understood, as the radii appear up to 20% larger than predicted by the population models. We demonstrate the spectroscopic detection viability in the secondary-to-primary light ratio regime of ~1-2% for the circumbinary host system Kepler-16. Semi-detached binaries are ideal targets to study the dynamical processes such as mass flow and accretion, and the associated thermal processes such as intensity variation due to distortion of the lobe-filling component and material inflow collisions with accretion disks. Overcontact binaries are very abundant, yet their evolution and radiative properties are poorly understood and conflicting theories exist to explain their population frequency and structure. In addition, we will measure eclipse timing variations for all program binaries that attest to the presence of perturbing third bodies (stellar and substellar!) or dynamical interaction between the components. By a dedicated, detailed, manual modeling of these sets of targets, we will be able to use Kepler's ultra-high precision photometry to a rewarding scientific end. Thanks to the unprecedented quality of Kepler data, this will be a highly focused effort that maximizes the scientific yield and the reliability of the results. Our team has ample experience dealing with Kepler data (PI Prsa serves as chair of the Eclipsing Binary Working Group in the Kepler Science Team), spectroscopic follow-up (Co-Is Mahadevan and Bender both have experience with radial velocity instrumentation and large spectroscopic surveys), and eclipsing binary modeling (PI Prsa and Co-I Devinney both have a long record of theoretical and computational development of modeling tools). The bulk of funding we are requesting is for two postdoctoral research fellows to conduct this work at 0.5 FTE/year each, for the total of 2 years.

First photometric study of two southern eclipsing binaries IS Tel and DW Aps

NASA Astrophysics Data System (ADS)

Özer, S.; Sürgit, D.; Erdem, A.; Öztürk, O.

2017-02-01

The paper presents the first photometric analysis of two southern eclipsing binary stars, IS Tel and DW Aps. Their V light curves from the All Sky Automated Survey were modelled by using Wilson-Devinney method. The final models give these two Algol-like binary stars as having detached configurations. Absolute parameters of the components of the systems were also estimated.

ORBITAL PHASE VARIATIONS OF THE ECCENTRIC GIANT PLANET HAT-P-2b

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lewis, Nikole K.; Showman, Adam P.; Knutson, Heather A.

2013-04-01

We present the first secondary eclipse and phase curve observations for the highly eccentric hot Jupiter HAT-P-2b in the 3.6, 4.5, 5.8, and 8.0 {mu}m bands of the Spitzer Space Telescope. The 3.6 and 4.5 {mu}m data sets span an entire orbital period of HAT-P-2b (P = 5.6334729 d), making them the longest continuous phase curve observations obtained to date and the first full-orbit observations of a planet with an eccentricity exceeding 0.2. We present an improved non-parametric method for removing the intrapixel sensitivity variations in Spitzer data at 3.6 and 4.5 {mu}m that robustly maps position-dependent flux variations. Wemore » find that the peak in planetary flux occurs at 4.39 {+-} 0.28, 5.84 {+-} 0.39, and 4.68 {+-} 0.37 hr after periapse passage with corresponding maxima in the planet/star flux ratio of 0.1138% {+-} 0.0089%, 0.1162% {+-} 0.0080%, and 0.1888% {+-} 0.0072% in the 3.6, 4.5, and 8.0 {mu}m bands, respectively. Our measured secondary eclipse depths of 0.0996% {+-} 0.0072%, 0.1031% {+-} 0.0061%, 0.071%{sub -0.013%}{sup +0.029,} and 0.1392% {+-} 0.0095% in the 3.6, 4.5, 5.8, and 8.0 {mu}m bands, respectively, indicate that the planet cools significantly from its peak temperature before we measure the dayside flux during secondary eclipse. We compare our measured secondary eclipse depths to the predictions from a one-dimensional radiative transfer model, which suggests the possible presence of a transient day side inversion in HAT-P-2b's atmosphere near periapse. We also derive improved estimates for the system parameters, including its mass, radius, and orbital ephemeris. Our simultaneous fit to the transit, secondary eclipse, and radial velocity data allows us to determine the eccentricity (e = 0.50910 {+-} 0.00048) and argument of periapse ({omega} = 188. Degree-Sign 09 {+-} 0. Degree-Sign 39) of HAT-P-2b's orbit with a greater precision than has been achieved for any other eccentric extrasolar planet. We also find evidence for a long-term linear trend in the radial velocity data. This trend suggests the presence of another substellar companion in the HAT-P-2 system, which could have caused HAT-P-2b to migrate inward to its present-day orbit via the Kozai mechanism.« less

Data Mining the Ogle-II I-band Database for Eclipsing Binary Stars

NASA Astrophysics Data System (ADS)

Ciocca, M.

2013-08-01

The OGLE I-band database is a searchable database of quality photometric data available to the public. During Phase 2 of the experiment, known as "OGLE-II", I-band observations were made over a period of approximately 1,000 days, resulting in over 1010 measurements of more than 40 million stars. This was accomplished by using a filter with a passband near the standard Cousins Ic. The database of these observations is fully searchable using the mysql database engine, and provides the magnitude measurements and their uncertainties. In this work, a program of data mining the OGLE I-band database was performed, resulting in the discovery of 42 previously unreported eclipsing binaries. Using the software package Peranso (Vanmuster 2011) to analyze the light curves obtained from OGLE-II, the eclipsing types, the epochs and the periods of these eclipsing variables were determined, to one part in 106. A preliminary attempt to model the physical parameters of these binaries was also performed, using the Binary Maker 3 software (Bradstreet and Steelman 2004).

A magnetic accretion switch in pre-cataclysmic binaries

NASA Astrophysics Data System (ADS)

Drake, Jeremy J.; Garraffo, Cecilia; Takei, Dai; Gaensicke, Boris

2014-02-01

We have investigated the mass accretion rate implied by published surface abundances of Si and C in the white dwarf component of the 3.62 h period pre-cataclysmic binary and planet host candidate QS Vir (DA+M2-4). Diffusion time-scales for gravitational settling imply dot{M} ˜ 10^{-16} M_{odot } yr-1 for the 1999 epoch of the observations, which is three orders of magnitude lower than measured from a 2006 XMM-Newton observation. This is the first time that large accretion rate variations have been seen in a detached pre-cataclysmic variable (pre-CV). A third body in a 14 yr eccentric orbit suggested in a recent eclipse timing study is too distant to perturb the central binary sufficiently to influence accretion. A hypothetical coronal mass ejection just prior to the XMM-Newton observation might explain the higher accretion rate, but the implied size and frequency of such events appear too great. We suggest accretion is most likely modulated by a magnetic cycle on the secondary acting as a wind `accretion switch', a mechanism that can be tested by X-ray and ultraviolet monitoring. If so, QS Vir and similar pre-CVs could provide powerful insights into hitherto inscrutable CV and M dwarf magnetospheres, and mass- and angular-momentum-loss rates.

New Precision Orbits of Bright Double-lined Spectroscopic Binaries. X. HD 96511, HR 7578, and KZ Andromedae

NASA Astrophysics Data System (ADS)

Fekel, Francis C.; Henry, Gregory W.; Tomkin, Jocelyn

2017-09-01

From an extensive number of newly acquired radial velocities we determine the orbital elements for three late-type dwarf systems, HD 96511, HR 7578, and KZ And. The orbital periods are 18.89737 ± 0.00002, 46.81610 ± 0.00006, and 3.0329113 ± 0.0000005 days, respectively, and all three systems are eccentric, although KZ And is just barely so. We have detected lines of the secondary of HD 96511 for the first time. The orbital dimensions (a 1 sin I and a 2 sin I) and minimum masses (m 1 sin3 I and m 2 sin3 I) of the binary components all have accuracies of 0.2% or better. Extensive photometry of the chromospherically active binary HR 7578 confirms a rather long rotation period of 16.446 ± 0.002 days and that the K3 V components do not eclipse. We have estimated the basic properties of the stars in the three systems and compared those results with evolutionary tracks. The results for KZ And that we computed with the revised Hipparcos parallax of van Leeuwen produce inconsistencies. That parallax appears to be too large, and so, instead, we used the original Hipparcos parallax of the common proper motion primary, which improves the results, although some problems remain.

Black Hole Mergers in Galactic Nuclei Induced by the Eccentric Kozai–Lidov Effect

NASA Astrophysics Data System (ADS)

Hoang, Bao-Minh; Naoz, Smadar; Kocsis, Bence; Rasio, Frederic A.; Dosopoulou, Fani

2018-04-01

Nuclear star clusters around a central massive black hole (MBH) are expected to be abundant in stellar black hole (BH) remnants and BH–BH binaries. These binaries form a hierarchical triple system with the central MBH, and gravitational perturbations from the MBH can cause high-eccentricity excitation in the BH–BH binary orbit. During this process, the eccentricity may approach unity, and the pericenter distance may become sufficiently small so that gravitational-wave emission drives the BH–BH binary to merge. In this work, we construct a simple proof-of-concept model for this process, and specifically, we study the eccentric Kozai–Lidov mechanism in unequal-mass, soft BH–BH binaries. Our model is based on a set of Monte Carlo simulations for BH–BH binaries in galactic nuclei, taking into account quadrupole- and octupole-level secular perturbations, general relativistic precession, and gravitational-wave emission. For a typical steady-state number of BH–BH binaries, our model predicts a total merger rate of ∼1–3 {Gpc} ‑3 {yr} ‑1, depending on the assumed density profile in the nucleus. Thus, our mechanism could potentially compete with other dynamical formation processes for merging BH–BH binaries, such as the interactions of stellar BHs in globular clusters or in nuclear star clusters without an MBH.

Observations of the eclipsing binary b Persei

NASA Astrophysics Data System (ADS)

Templeton, Matthew R.

2015-01-01

Dr. Robert Zavala (USNO-Flagstaff) et al. request V time-series observations of the bright variable star b Persei 7-21 January 2015 UT, in hopes of catching a predicted eclipse on January 15. This is a follow-up to the February 2013 campaign announced in Alert Notice 476, and will be used as a photometric comparison for upcoming interferometric observations with the Navy Precision Optical Interferometer (NPOI) in Arizona. b Per (V=4.598, B-V=0.054) is ideal for photoelectric photometers or DSLR cameras. Telescopic CCD observers may observe by stopping down larger apertures. Comparison and check stars assigned by PI: Comp: SAO 24412, V=4.285, B-V = -0.013; Check: SAO 24512, V=5.19, B-V = -0.05. From the PI: "[W]e wanted to try and involve AAVSO observers in a follow up to our successful detection of the b Persei eclipse of Feb 2013, AAVSO Alert Notice 476 and Special Notice 333. Our goal now is to get good time resolution photometry as the third star passes in front of the close ellipsoidal binary. The potential for multiple eclipses exists. The close binary has a 1.5 day orbital period, and the eclipsing C component requires about 4 days to pass across the close binary pair. The primary eclipse depth is 0.15 magnitude. Photometry to 0.02 or 0.03 mags would be fine to detect this eclipse. Eclipse prediction date (JD 2457033.79 = 2015 01 11 UT, ~+/- 1 day) is based on one orbital period from the 2013 eclipse." More information is available at PI's b Persei eclipse web page: http://inside.warren-wilson.edu/~dcollins/bPersei/. Finder charts with sequence may be created using the AAVSO Variable Star Plotter (https://www.aavso.org/vsp). Observations should be submitted to the AAVSO International Database. See full Alert Notice for more details and information on the targets.

ECLIPSING BINARY SCIENCE VIA THE MERGING OF TRANSIT AND DOPPLER EXOPLANET SURVEY DATA-A CASE STUDY WITH THE MARVELS PILOT PROJECT AND SuperWASP

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fleming, Scott W.; Ge Jian; De Lee, Nathan M.

2011-08-15

Exoplanet transit and Doppler surveys discover many binary stars during their operation that can be used to conduct a variety of ancillary science. Specifically, eclipsing binary stars can be used to study the stellar mass-radius relationship and to test predictions of theoretical stellar evolution models. By cross-referencing 24 binary stars found in the MARVELS Pilot Project with SuperWASP photometry, we find two new eclipsing binaries, TYC 0272-00458-1 and TYC 1422-01328-1, which we use as case studies to develop a general approach to eclipsing binaries in survey data. TYC 0272-00458-1 is a single-lined spectroscopic binary for which we calculate a massmore » of the secondary and radii for both components using reasonable constraints on the primary mass through several different techniques. For a primary mass of M{sub 1} = 0.92 {+-} 0.1 M{sub sun}, we find M{sub 2} = 0.610 {+-} 0.036 M{sub sun}, R{sub 1} = 0.932 {+-} 0.076 R{sub sun}, and R{sub 2} = 0.559 {+-} 0.102 R{sub sun}, and find that both stars have masses and radii consistent with model predictions. TYC 1422-01328-1 is a triple-component system for which we can directly measure the masses and radii of the eclipsing pair. We find that the eclipsing pair consists of an evolved primary star (M{sub 1} = 1.163 {+-} 0.034 M{sub sun}, R{sub 1} = 2.063 {+-} 0.058 R{sub sun}) and a G-type dwarf secondary (M{sub 2} = 0.905 {+-} 0.067 M{sub sun}, R{sub 2} = 0.887 {+-} 0.037 R{sub sun}). We provide the framework necessary to apply this analysis to much larger data sets.« less

Frequency and time-domain inspiral templates for comparable mass compact binaries in eccentric orbits

NASA Astrophysics Data System (ADS)

Tanay, Sashwat; Haney, Maria; Gopakumar, Achamveedu

2016-03-01

Inspiraling compact binaries with non-negligible orbital eccentricities are plausible gravitational wave (GW) sources for the upcoming network of GW observatories. In this paper, we present two prescriptions to compute post-Newtonian (PN) accurate inspiral templates for such binaries. First, we adapt and extend the postcircular scheme of Yunes et al. [Phys. Rev. D 80, 084001 (2009)] to obtain a Fourier-domain inspiral approximant that incorporates the effects of PN-accurate orbital eccentricity evolution. This results in a fully analytic frequency-domain inspiral waveform with Newtonian amplitude and 2PN-order Fourier phase while incorporating eccentricity effects up to sixth order at each PN order. The importance of incorporating eccentricity evolution contributions to the Fourier phase in a PN-consistent manner is also demonstrated. Second, we present an accurate and efficient prescription to incorporate orbital eccentricity into the quasicircular time-domain TaylorT4 approximant at 2PN order. New features include the use of rational functions in orbital eccentricity to implement the 1.5PN-order tail contributions to the far-zone fluxes. This leads to closed form PN-accurate differential equations for evolving eccentric orbits, and the resulting time-domain approximant is accurate and efficient to handle initial orbital eccentricities ≤0.9 . Preliminary GW data analysis implications are probed using match estimates.

Induced Ellipticity for Inspiraling Binary Systems

NASA Astrophysics Data System (ADS)

Randall, Lisa; Xianyu, Zhong-Zhi

2018-01-01

Although gravitational waves tend to erase eccentricity of an inspiraling binary system, ellipticity can be generated in the presence of surrounding matter. We present a semianalytical method for understanding the eccentricity distribution of binary black holes (BHs) in the presence of a supermassive BH in a galactic center. Given a matter distribution, we show how to determine the resultant eccentricity analytically in the presence of both tidal forces and evaporation up to one cutoff and one matter-distribution-independent function, paving the way for understanding the environment of detected inspiraling BHs. We furthermore generalize Kozai–Lidov dynamics to situations where perturbation theory breaks down for short time intervals, allowing more general angular momentum exchange, such that eccentricity is generated even when all bodies orbit in the same plane.

Updated O-C Diagrams for Several Bright HW Vir Binaries Observed with the Evryscope

NASA Astrophysics Data System (ADS)

Corcoran, Kyle A.; Barlow, Brad; Corbett, Hank; Fors, Octavi; Howard, Ward S.; Law, Nicholas; Ratzloff, Jeff

2018-01-01

HW Vir systems are eclipsing, post-common-envelope binaries consisting of a hot subdwarf star and a cooler M dwarf or brown dwarf companion. They show a strong reflection effect and have characteristically short orbital periods of only a few hours, allowing observers to detect multiple eclipses per night. Observed minus calculated (O-C) studies allow one to measure miniscule variations in the orbital periods of these systems by comparing observed eclipse timings to a calculated ephemeris. This technique is useful for detecting period changes due to secular evolution of the binary, gravitational wave emission, or reflex motion from an orbiting circumbinary object. Numerous eclipse timings obtained over several years are vital to the proper interpretation and analysis of O-C diagrams. The Evryscope – an array of twenty-four individual telescopes built by UNC and deployed on Cerro Tololo – images the entire Southern sky once every two minutes, producing an insurmountable amount of data for objects brighter than 16th magnitude. The cadence with which Evryscope exposes makes it an unparalleled tool for O-C analyses of HW Vir binaries; it will catalogue thousands of eclipses over the next several years. Here we present updated O-C diagrams for several HW Vir binaries using recent measurements from the Evryscope. We also use observations of AA Dor, an incredibly stable astrophysical clock, to characterize the accuracy of the Evryscope’s timestamps.

1SWASP J200503.05-343726.5: A high mass ratio eclipsing binary near the period limit

NASA Astrophysics Data System (ADS)

Bin, Zhang; Shengbang, Qian; Zejda, Miloslav; Liying, Zhu; Nianping, Liu

2017-07-01

First CCD photometric light curves of the eclipsing binary system 1SWASP J200503.05-343726.5 are presented. Our complete light curves in V, R and I bands using the Bessell filter show an out-of-eclipsing distortion, which means that the components of the system may be active. The preliminary photometric solutions with a cool star-spot are derived by using the 2013 version of the Wilson-Devinney (W-D) code. The photometric solutions suggest that 1SWASP J200503.05-343726.5 is a shallow-contact eclipsing binary(f = 9.0 %) with a mass ratio of q = 1.0705 , which is very high for late-type binary systems near the period limit. The primary component is about 230 K hotter than the secondary component. Based on our new CCD eclipse times, the orbital period change was analyzed. According to O - C diagram, the orbital period of the 1SWASP J200503.05-343726.5 shows an increase at a rate of P˙ = + 5.43 ×10-8 days year-1. The period increase may be caused by mass transfer from the less massive component to the more massive one. This shallow-contact system may be formed from a detached short-period binary via orbital shrinkage because of dynamical interactions with a third component or by magnetic braking.

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

NASA Astrophysics Data System (ADS)

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.

Interfacing modeling suite Physics Of Eclipsing Binaries 2.0 with a Virtual Reality Platform

NASA Astrophysics Data System (ADS)

Harriett, Edward; Conroy, Kyle; Prša, Andrej; Klassner, Frank

2018-01-01

To explore alternate methods for modeling eclipsing binary stars, we extrapolate upon PHOEBE’s (PHysics Of Eclipsing BinariEs) capabilities in a virtual reality (VR) environment to create an immersive and interactive experience for users. The application used is Vizard, a python-scripted VR development platform for environments such as Cave Automatic Virtual Environment (CAVE) and other off-the-shelf VR headsets. Vizard allows the freedom for all modeling to be precompiled without compromising functionality or usage on its part. The system requires five arguments to be precomputed using PHOEBE’s python front-end: the effective temperature, flux, relative intensity, vertex coordinates, and orbits; the user can opt to implement other features from PHOEBE to be accessed within the simulation as well. Here we present the method for making the data observables accessible in real time. An Occulus Rift will be available for a live showcase of various cases of VR rendering of PHOEBE binary systems including detached and contact binary stars.

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

NASA Astrophysics Data System (ADS)

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.

An ultraviolet investigation of the unusual eclipsing binary system FF AQR

NASA Technical Reports Server (NTRS)

Dorren, J. D.; Guinan, E. F.; Sion, E. M.

1982-01-01

A series of seven low dispersion IUE exposures in ultraviolet and wavelength regions obtained on December 6, 1981 during the eclipse of the subdwarf, during egress, and out of eclipse is analyzed. These observations and the binary phase at which they were made are shown on a schematic representation of the V-band light curve obtained in 1975. The depth in V is 0.15 mag. The circles are IUE V magnitudes from FES measures obtained during the observing run. They indicate an eclipse depth some 0.05 mag lower than expected, possibly due to difficulties with the color term in the FES calibration. The eclipse depths of Dworetsky in U, B and V were assumed in the calculations.

A NEW CLASS OF NASCENT ECLIPSING BINARIES WITH EXTREME MASS RATIOS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Moe, Maxwell; Stefano, Rosanne Di, E-mail: mmoe@cfa.harvard.edu

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-massmore » 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.« less

Distinguishing between Formation Channels for Binary Black Holes with LISA

NASA Astrophysics Data System (ADS)

Breivik, Katelyn; Rodriguez, Carl L.; Larson, Shane L.; Kalogera, Vassiliki; Rasio, Frederic A.

2016-10-01

The recent detections of GW150914 and GW151226 imply an abundance of stellar-mass binary black hole (BBH) mergers in the local universe. While ground-based gravitational wave detectors are limited to observing the final moments before a binary merges, space-based detectors, such as the Laser Interferometer Space Antenna (LISA), can observe binaries at lower orbital frequencies where such systems may still encode information about their formation histories. In particular, the orbital eccentricity and mass of BBHs in the LISA frequency band can be used together to discriminate between binaries formed in isolation in galactic fields and those formed in dense stellar environments such as globular clusters. In this letter, we explore the orbital eccentricity and mass of BBH populations as they evolve through the LISA frequency band. Overall we find that there are two distinct populations discernible by LISA. We show that up to ∼ 90 % of binaries formed either dynamically or in isolation have eccentricities that are measurable with LISA. Finally, we note how measured eccentricities of low-mass BBHs evolved in isolation could provide detailed constraints on the physics of black hole natal kicks and common-envelope evolution.

Spitzer secondary eclipses of Qatar-1b

NASA Astrophysics Data System (ADS)

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

EPIC 219217635: A Doubly Eclipsing Quadruple System Containing an Evolved Binary

NASA Astrophysics Data System (ADS)

Borkovits, T.; Albrecht, S.; Rappaport, S.; Nelson, L.; Vanderburg, A.; Gary, B. L.; Tan, T. G.; Justesen, A. B.; Kristiansen, M. H.; Jacobs, T. L.; LaCourse, D.; Ngo, H.; Wallack, N.; Ruane, G.; Mawet, D.; Howell, S. B.; Tronsgaard, R.

2018-05-01

We have discovered a doubly eclipsing, bound, quadruple star system in the field of K2 Campaign 7. EPIC 219217635 is a stellar image with Kp = 12.7 that contains an eclipsing binary (`EB') with PA = 3.59470 d and a second EB with PB = 0.61825 d. We have obtained followup radial-velocity (`RV') spectroscopy observations, adaptive optics imaging, as well as ground-based photometric observations. From our analysis of all the observations, we derive good estimates for a number of the system parameters. We conclude that (1) both binaries are bound in a quadruple star system; (2) a linear trend to the RV curve of binary A is found over a 2-year interval, corresponding to an acceleration, \\dot{γ }= 0.0024 ± 0.0007 cm s-2; (3) small irregular variations are seen in the eclipse-timing variations (`ETVs') detected over the same interval; (4) the orbital separation of the quadruple system is probably in the range of 8-25 AU; and (5) the orbital planes of the two binaries must be inclined with respect to each other by at least 25°. In addition, we find that binary B is evolved, and the cooler and currently less massive star has transferred much of its envelope to the currently more massive star. We have also demonstrated that the system is sufficiently bright that the eclipses can be followed using small ground-based telescopes, and that this system may be profitably studied over the next decade when the outer orbit of the quadruple is expected to manifest itself in the ETV and/or RV curves.

Effects of Accretion Disks on Spins and Eccentricities of Binaries, and Implications for Gravitational Waves

NASA Technical Reports Server (NTRS)

Baker, John

2012-01-01

Effects of accretion disks on spins and eccentricities of binaries, and implications for gravitational waves. John Baker Space-based gravitational wave observations will allow exquisitely precise measurements of massive black hole binary properties. Through several recently suggested processes, these properties may depend on interactions with accretion disks through the merger process. I will discuss ways that accretion may influence those binary properties which may be probed by gravitational-wave observations.

Dynamics of binary and planetary-system interaction with disks - Eccentricity changes

NASA Technical Reports Server (NTRS)

Atrymowicz, Pawel

1992-01-01

Protostellar and protoplanetary systems, as well as merging galactic nuclei, often interact tidally and resonantly with the astrophysical disks via gravity. Underlying our understanding of the formation processes of stars, planets, and some galaxies is a dynamical theory of such interactions. Its main goals are to determine the geometry of the binary-disk system and, through the torque calculations, the rate of change of orbital elements of the components. We present some recent developments in this field concentrating on eccentricity driving mechanisms in protoplanetary and protobinary systems. In those two types of systems the result of the interaction is opposite. A small body embedded in a disk suffers a decrease of orbital eccentricity, whereas newly formed binary stars surrounded by protostellar disks may undergo a significant orbital evolution increasing their eccentricities.

Planet Formation in Binaries: Dynamics of Planetesimals Perturbed by the Eccentric Protoplanetary Disk and the Secondary

NASA Astrophysics Data System (ADS)

Silsbee, Kedron; Rafikov, Roman R.

2015-01-01

Detections of planets in eccentric, close (separations of ~20 AU) binary systems such as α Cen or γ Cep provide an important test of planet formation theories. Gravitational perturbations from the companion are expected to excite high planetesimal eccentricities, resulting in destruction rather than growth of objects with sizes of up to several hundred kilometers in collisions of similar-sized bodies. It was recently suggested that the gravity of a massive axisymmetric gaseous disk in which planetesimals are embedded drives rapid precession of their orbits, suppressing eccentricity excitation. However, disks in binaries are themselves expected to be eccentric, leading to additional planetesimal excitation. Here we develop a secular theory of eccentricity evolution for planetesimals perturbed by the gravity of an elliptical protoplanetary disk (neglecting gas drag) and the companion. For the first time, we derive an expression for the disturbing function due to an eccentric disk, which can be used for a variety of other astrophysical problems. We obtain explicit analytical solutions for planetesimal eccentricity evolution neglecting gas drag and delineate four different regimes of dynamical excitation. We show that in systems with massive (gsim 10-2 M ⊙) disks, planetesimal eccentricity is usually determined by the gravity of the eccentric disk alone, and is comparable to the disk eccentricity. As a result, the latter imposes a lower limit on collisional velocities of solids, making their growth problematic. In the absence of gas drag, this fragmentation barrier can be alleviated if the gaseous disk rapidly precesses or if its own self-gravity is efficient at lowering disk eccentricity.

COMPLEX VARIABILITY OF THE H{alpha} EMISSION LINE PROFILE OF THE T TAURI BINARY SYSTEM KH 15D: THE INFLUENCE OF ORBITAL PHASE, OCCULTATION BY THE CIRCUMBINARY DISK, AND ACCRETION PHENOMENA

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hamilton, Catrina M.; Johns-Krull, Christopher M.; Mundt, Reinhard

2012-06-01

We have obtained 48 high-resolution echelle spectra of the pre-main-sequence eclipsing binary system KH 15D (V582 Mon, P = 48.37 days, e {approx} 0.6, M{sub A} = 0.6 M{sub Sun }, M{sub B} = 0.7 M{sub Sun }). The eclipses are caused by a circumbinary disk (CBD) seen nearly edge on, which at the epoch of these observations completely obscured the orbit of star B and a large portion of the orbit of star A. The spectra were obtained over five contiguous observing seasons from 2001/2002 to 2005/2006 while star A was fully visible, fully occulted, and during several ingressmore » and egress events. The H{alpha} line profile shows dramatic changes in these time series data over timescales ranging from days to years. A fraction of the variations are due to 'edge effects' and depend only on the height of star A above or below the razor sharp edge of the occulting disk. Other observed variations depend on the orbital phase: the H{alpha} emission line profile changes from an inverse P-Cygni-type profile during ingress to an enhanced double-peaked profile, with both a blue and a red emission component, during egress. Each of these interpreted variations are complicated by the fact that there is also a chaotic, irregular component present in these profiles. We find that the complex data set can be largely understood in the context of accretion onto the stars from a CBD with gas flows as predicted by the models of eccentric T Tauri binaries put forward by Artymowicz and Lubow, Guenther and Kley, and de Val-Borro et al. In particular, our data provide strong support for the pulsed accretion phenomenon, in which enhanced accretion occurs during and after perihelion passage.« less

Correlations among the parameters of the spherical model for eclipsing binaries

NASA Technical Reports Server (NTRS)

Sobieski, S.; White, J. E.

1971-01-01

Correlation coefficients were computed to investigate the parameters for describing the spherical model of an eclipsing binary system. Regions in parameter hyperspace were identified where strong correlations exist and, by implication, the solution determinacy is low. The results are presented in tabular form for a large number of system configurations.

Precision of Times-of-Minima and the Detection of Low-Mass Third Bodies Orbiting Eclipsing Binaries

NASA Astrophysics Data System (ADS)

Genet, R. M.; Smith, T. C.

2004-12-01

Low-mass third bodies orbiting eclipsing binaries are difficult to detect by way of periodic shifts in photometric times-of-minima because the observational precision of these timings are of the same order as the expected effects of any low-mass companions. We are implementing three approaches to increasing the precision of our times-of-minima. First, we are obtaining many times-of-minima by utilizing relatively low-cost, dedicated telescopes and CCD cameras (10- and 14-inch Meade LX-200 telescopes and SBIG ST7-XE cameras). Operating in a semiautomatic mode, we select an eclipsing binary system, based on its placement in the sky, and observe it all night long - usually many nights in a row. We choose binaries with short enough periods to assure us of obtaining a complete light curve (and hence an eclipse) every night we observe. Second, we are striving to increase the photometric precision of each observation through the use of multiple comparison stars (ensemble photometry). We are also, in conjunction with California Polytechnic State University, investigating other ways of increasing the photometric precision of these low-cost systems (see E. Sturm this conference). Finally, we are utilizing complete, as opposed to partial, light curves in our analysis. Information outside primary eclipses is gathered as a matter of course, and its use can improve precision. A total of 186 complete light curves were obtained at the Dark Ridge and Orion Observatories during the 2004 observing season on six eclipsing binaries (TZ Boo, V523 Cas, RW Com, V1191 Cyg, GM Dra, and V400 Lyr). Please see T. Smith and R. Genet (this conference) for preliminary results on V523 Cas (30+ complete light curves).

Eccentric black hole mergers forming in globular clusters

NASA Astrophysics Data System (ADS)

Samsing, Johan

2018-05-01

We derive the probability for a newly formed binary black hole (BBH) to undergo an eccentric gravitational wave (GW) merger during binary-single interactions inside a stellar cluster. By integrating over the hardening interactions such a BBH must undergo before ejection, we find that the observable rate of BBH mergers with eccentricity >0.1 at 10 Hz relative to the rate of circular mergers can be as high as ˜5 % for a typical globular cluster (GC). This further suggests that BBH mergers forming through GW captures in binary-single interactions, eccentric or not, are likely to constitute ˜10 % of the total BBH merger rate from GCs. Such GW capture mergers can only be probed with an N -body code that includes general relativistic corrections, which explains why recent Newtonian cluster studies have not been able to resolve this population. Finally, we show that the relative rate of eccentric BBH mergers depends on the compactness of their host cluster, suggesting that an observed eccentricity distribution can be used to probe the origin of BBH mergers.

Observational Evidence for Tidal Interaction in Close Binary Systems

NASA Astrophysics Data System (ADS)

Mazeh, T.

This paper reviews the rich corpus of observational evidence for tidal effects, mostly based on photometric and radial-velocity measurements. This is done in a period when the study of binaries is being revolutionized by large-scaled photometric surveys that are detecting many thousands of new binaries and tens of extrasolar planets. We begin by examining the short-term effects, such as ellipsoidal variability and apsidal motion. We next turn to the long-term effects, of which circularization was studied the most: a transition period between circular and eccentric orbits has been derived for eight coeval samples of binaries. The study of synchronization and spin-orbit alignment is less advanced. As binaries are supposed to reach synchronization before circularization, one can expect finding eccentric binaries in pseudo-synchronization state, the evidence for which is reviewed. We also discuss synchronization in PMS and young stars, and compare the emerging timescale with the circularization timescale. We next examine the tidal interaction in close binaries that are orbited by a third distant companion, and review the effect of pumping the binary eccentricity by the third star. We elaborate on the impact of the pumped eccentricity on the tidal evolution of close binaries residing in triple systems, which may shrink the binary separation. Finally we consider the extrasolar planets and the observational evidence for tidal interaction with their parent stars. This includes a mechanism that can induce radial drift of short-period planets, either inward or outward, depending on the planetary radial position relative to the corotation radius. Another effect is the circularization of planetary orbits, the evidence for which can be found in eccentricity-versus-period plot of the planets already known. Whenever possible, the paper attempts to address the possible confrontation between theory and observations, and to point out noteworthy cases and observations that can be performed in the future and may shed some light on the key questions that remain open.

The Late-type Eclipsing Binaries in the Large Magellanic Cloud: Catalog of Fundamental Physical Parameters

NASA Astrophysics Data System (ADS)

Graczyk, Dariusz; Pietrzyński, Grzegorz; Thompson, Ian B.; Gieren, Wolfgang; Pilecki, Bogumił; Konorski, Piotr; Villanova, Sandro; Górski, Marek; Suchomska, Ksenia; Karczmarek, Paulina; Stepień, Kazimierz; Storm, Jesper; Taormina, Mónica; Kołaczkowski, Zbigniew; Wielgórski, Piotr; Narloch, Weronika; Zgirski, Bartłomiej; Gallenne, Alexandre; Ostrowski, Jakub; Smolec, Radosław; Udalski, Andrzej; Soszyński, Igor; Kervella, Pierre; Nardetto, Nicolas; Szymański, Michał K.; Wyrzykowski, Łukasz; Ulaczyk, Krzysztof; Poleski, Radosław; Pietrukowicz, Paweł; Kozłowski, Szymon; Skowron, Jan; Mróz, Przemysław

2018-06-01

We present a determination of the precise fundamental physical parameters of 20 detached, double-lined, eclipsing binary stars in the Large Magellanic Cloud (LMC) containing G- or early K-type giant stars. Eleven are new systems; the remaining nine are systems already analyzed by our team for which we present updated parameters. The catalog results from our long-term survey of eclipsing binaries in the Magellanic Clouds suitable for high-precision determination of distances (the Araucaria Project). The V-band brightnesses of the systems range from 15.4 to 17.7 mag, and their orbital periods range from 49 to 773 days. Six systems have favorable geometry showing total eclipses. The absolute dimensions of all eclipsing binary components are calculated with a precision of better than 3%, and all systems are suitable for a precise distance determination. The measured stellar masses are in the range 1.4 to 4.6 M ⊙, and comparison with the MESA isochrones gives ages between 0.1 and 2.1 Gyr. The systems show an age–metallicity relation with no evolution of metallicity for systems older than 0.6 Gyr, followed by a rise to a metallicity maximum at age 0.5 Gyr and then a slow metallicity decrease until 0.1 Gyr. Two systems have components with very different masses: OGLE LMC-ECL-05430 and OGLE LMC-ECL-18365. Neither system can be fitted by a single stellar evolution isochrone, explained by a past mass transfer scenario in the case of ECL-18365 and a gravitational capture or hierarchical binary merger scenario in the case of ECL-05430. The longest-period system, OGLE LMC SC9_230659, shows a surprising apsidal motion that shifts the apparent position of the eclipses. This is a clear sign of a physical companion to the system; however, neither investigation of the spectra nor light-curve analysis indicates a third-light contribution larger than 2%–3%. In one spectrum of OGLE LMC-ECL-12669, we noted a peculiar dimming of one of the components by 65% well outside of the eclipses. We interpret this observation as arising from an extremely rare occultation event, as a foreground Galactic object covers only one component of an extragalactic eclipsing binary.

The disruption of multiplanet systems through resonance with a binary orbit.

PubMed

Touma, Jihad R; Sridhar, S

2015-08-27

Most exoplanetary systems in binary stars are of S-type, and consist of one or more planets orbiting a primary star with a wide binary stellar companion. Planetary eccentricities and mutual inclinations can be large, perhaps forced gravitationally by the binary companion. Earlier work on single planet systems appealed to the Kozai-Lidov instability wherein a sufficiently inclined binary orbit excites large-amplitude oscillations in the planet's eccentricity and inclination. The instability, however, can be quenched by many agents that induce fast orbital precession, including mutual gravitational forces in a multiplanet system. Here we report that orbital precession, which inhibits Kozai-Lidov cycling in a multiplanet system, can become fast enough to resonate with the orbital motion of a distant binary companion. Resonant binary forcing results in dramatic outcomes ranging from the excitation of large planetary eccentricities and mutual inclinations to total disruption. Processes such as planetary migration can bring an initially non-resonant system into resonance. As it does not require special physical or initial conditions, binary resonant driving is generic and may have altered the architecture of many multiplanet systems. It can also weaken the multiplanet occurrence rate in wide binaries, and affect planet formation in close binaries.

VizieR Online Data Catalog: Minima of 41 binaries from entire Kepler mission (Gies+, 2015)

NASA Astrophysics Data System (ADS)

Gies, D. R.; Matson, R. A.; Guo, Z.; Lester, K. V.; Orosz, J. A.; Peters, G. J.

2016-06-01

We embarked on a search for eclipse timing variations among a subset of 41 eclipsing binaries that were identified prior to the start of Kepler observations (see our first paper, Gies et al. 2012, cat. J/AJ/143/137). Our first paper documented the eclipse times in observations made over quarters Q0-Q9 (2009.3-2011.5). Now with the Kepler mission complete with observations through Q17 (ending 2013.4), we present here the eclipse timings for our sample of 41 binaries over the entire duration of the mission. The associated times given in our first paper were based upon UTC (Coordinated Universal Time) while the current set uses TDB (Barycentric Dynamical Time), and here we report the times in reduced Barycentric Julian Date (BJD-2400000 days). We used the Simple Aperture Photometry (SAP) flux except in the case of KIC04678873. The list of targets appears in Table1. The eclipse timing measurements were made in almost the same way as described in our first paper. Our measurements appear in Table2. (2 data files).

A complete waveform model for compact binaries on eccentric orbits

NASA Astrophysics Data System (ADS)

George, Daniel; Huerta, Eliu; Kumar, Prayush; Agarwal, Bhanu; Schive, Hsi-Yu; Pfeiffer, Harald; Chu, Tony; Boyle, Michael; Hemberger, Daniel; Kidder, Lawrence; Scheel, Mark; Szilagyi, Bela

2017-01-01

We present a time domain waveform model that describes the inspiral, merger and ringdown of compact binary systems whose components are non-spinning, and which evolve on orbits with low to moderate eccentricity. We show that this inspiral-merger-ringdown waveform model reproduces the effective-one-body model for black hole binaries with mass-ratios between 1 to 15 in the zero eccentricity limit over a wide range of the parameter space under consideration. We use this model to show that the gravitational wave transients GW150914 and GW151226 can be effectively recovered with template banks of quasicircular, spin-aligned waveforms if the eccentricity e0 of these systems when they enter the aLIGO band at a gravitational wave frequency of 14 Hz satisfies e0GW 150914 <= 0 . 15 and e0GW 151226 <= 0 . 1 .

An Eccentric Binary Millisecond Pulsar in the Galactic Plane

NASA Technical Reports Server (NTRS)

Champion, David J.; Ransom, Scott M.; Lazarus, Patrick; Camilo, Fernando; Bassa, Cess; Kaspi, Victoria M.; Nice, David J.; Freire, Paulo C. C.; Stairs, Ingrid H.; vanLeeuwen, Joeri;

The dynamical mass of a classical Cepheid variable star in an eclipsing binary system.

PubMed

Pietrzyński, G; Thompson, I B; Gieren, W; Graczyk, D; Bono, G; Udalski, A; Soszyński, I; Minniti, D; Pilecki, B

2010-11-25

Stellar pulsation theory provides a means of determining the masses of pulsating classical Cepheid supergiants-it is the pulsation that causes their luminosity to vary. Such pulsational masses are found to be smaller than the masses derived from stellar evolution theory: this is the Cepheid mass discrepancy problem, for which a solution is missing. An independent, accurate dynamical mass determination for a classical Cepheid variable star (as opposed to type-II Cepheids, low-mass stars with a very different evolutionary history) in a binary system is needed in order to determine which is correct. The accuracy of previous efforts to establish a dynamical Cepheid mass from Galactic single-lined non-eclipsing binaries was typically about 15-30% (refs 6, 7), which is not good enough to resolve the mass discrepancy problem. In spite of many observational efforts, no firm detection of a classical Cepheid in an eclipsing double-lined binary has hitherto been reported. Here we report the discovery of a classical Cepheid in a well detached, double-lined eclipsing binary in the Large Magellanic Cloud. We determine the mass to a precision of 1% and show that it agrees with its pulsation mass, providing strong evidence that pulsation theory correctly and precisely predicts the masses of classical Cepheids.

Correlations among the parameters of the spherical model for eclipsing binaries.

NASA Technical Reports Server (NTRS)

Sobieski, S.; White, J.

1973-01-01

Correlation coefficients have been computed to investigate the parameters used to describe the spherical model of an eclipsing binary system. Regions in parameter hyperspace have been identified where strong correlations exist and, by implication, the solution determinacy is low. The results are presented in tabular form for a large number of system configurations.

Photoelectric observations of the long-period eclipsing binaries at Yonsei University Observatory

NASA Technical Reports Server (NTRS)

Nha, I. S.; Lee, Y. S.; Chun, Y. W.; Kim, H. I.; Kim, Y. S.

1985-01-01

A long term project (ten-years; 1982-92) for the photoelectric observation in the UBV passbands of selected eclipsing binaries with P 10 days has initiated at Yonsei University Observatory using 40-cm and 61-cm reflectors. The instrumentation used and the observation techniques and the reduction procedures applied to this investigation are described.

Eclipsing Binary V1178 Tau: A Reddening Independent Determination of the Age and Distance to NGC 1817

NASA Astrophysics Data System (ADS)

Hedlund, Anne; Sandquist, Eric L.; Arentoft, Torben; Brogaard, Karsten; Grundahl, Frank; Stello, Dennis; Bedin, Luigi R.; Libralato, Mattia; Malavolta, Luca; Nardiello, Domenico; Molenda-Zakowicz, Joanna; Vanderburg, Andrew

2018-06-01

V1178 Tau is a double-lined spectroscopic eclipsing binary in NGC1817, one of the more massive clusters observed in the K2 mission. We have determined the orbital period (P = 2.20 d) for the first time, and we model radial velocity measurements from the HARPS and ALFOSC spectrographs, light curves collected by Kepler, and ground based light curves using the Eclipsing Light Curve code (ELC, Orosz & Hauschildt 2000). We present masses and radii for the stars in the binary, allowing for a reddening-independent means of determining the cluster age. V1178 Tau is particularly useful for calculating the age of the cluster because the stars are close to the cluster turnoff, providing a more precise age determination. Furthermore, because one of the stars in the binary is a delta Scuti variable, the analysis provides improved insight into their pulsations.

HII 2407: AN ECLIPSING BINARY REVEALED BY K2 OBSERVATIONS OF THE PLEIADES

DOE Office of Scientific and Technical Information (OSTI.GOV)

David, Trevor J.; Hillenbrand, Lynne A.; Zhang, Celia

2015-11-20

The star HII 2407 is a member of the relatively young Pleiades star cluster and was previously discovered to be a single-lined spectroscopic binary. It is newly identified here within Kepler/K2 photometric time series data as an eclipsing binary system. Mutual fitting of the radial velocity and photometric data leads to an orbital solution and constraints on fundamental stellar parameters. While the primary has arrived on the main sequence, the secondary is still pre-main sequence and we compare our results for the M/M{sub ⊙} and R/R{sub ⊙} values with stellar evolutionary models. We also demonstrate that the system is likelymore » to be tidally synchronized. Follow-up infrared spectroscopy is likely to reveal the lines of the secondary, allowing for dynamically measured masses and elevating the system to benchmark eclipsing binary status.« less

Photometric Study of the Pulsating, Eclipsing Binary OO Dra

NASA Astrophysics Data System (ADS)

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

2014-12-01

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.

Photometric study of the pulsating, eclipsing binary OO DRA

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, X. B.; Deng, L. C.; Tian, J. F.

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.more » 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.« less

PLANET FORMATION IN BINARIES: DYNAMICS OF PLANETESIMALS PERTURBED BY THE ECCENTRIC PROTOPLANETARY DISK AND THE SECONDARY

DOE Office of Scientific and Technical Information (OSTI.GOV)

Silsbee, Kedron; Rafikov, Roman R., E-mail: ksilsbee@astro.princeton.edu

2015-01-10

Detections of planets in eccentric, close (separations of ∼20 AU) binary systems such as α Cen or γ Cep provide an important test of planet formation theories. Gravitational perturbations from the companion are expected to excite high planetesimal eccentricities, resulting in destruction rather than growth of objects with sizes of up to several hundred kilometers in collisions of similar-sized bodies. It was recently suggested that the gravity of a massive axisymmetric gaseous disk in which planetesimals are embedded drives rapid precession of their orbits, suppressing eccentricity excitation. However, disks in binaries are themselves expected to be eccentric, leading to additionalmore » planetesimal excitation. Here we develop a secular theory of eccentricity evolution for planetesimals perturbed by the gravity of an elliptical protoplanetary disk (neglecting gas drag) and the companion. For the first time, we derive an expression for the disturbing function due to an eccentric disk, which can be used for a variety of other astrophysical problems. We obtain explicit analytical solutions for planetesimal eccentricity evolution neglecting gas drag and delineate four different regimes of dynamical excitation. We show that in systems with massive (≳ 10{sup –2} M {sub ☉}) disks, planetesimal eccentricity is usually determined by the gravity of the eccentric disk alone, and is comparable to the disk eccentricity. As a result, the latter imposes a lower limit on collisional velocities of solids, making their growth problematic. In the absence of gas drag, this fragmentation barrier can be alleviated if the gaseous disk rapidly precesses or if its own self-gravity is efficient at lowering disk eccentricity.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

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

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{sub C}I{sub 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{sub B} = 1.090 ± 0.010 M{sub ⊙} and M{sub C} = 1.075 ± 0.013 M{sub ⊙}, and radii R{sub B} = 1.099 ± 0.006 ± 0.005 R{sub ⊙} and R{sub C} = 1.069 ± 0.006 ± 0.013 R{submore » ⊙}. 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{sub A} = 1.251 ± 0.057 M{sub ⊙}. 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){sub 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.« less

Confusing Binaries: The Role of Stellar Binaries in Biasing Disk Properties in the Galactic Center

NASA Astrophysics Data System (ADS)

Naoz, Smadar; Ghez, Andrea M.; Hees, Aurelien; Do, Tuan; Witzel, Gunther; Lu, Jessica R.

2018-02-01

The population of young stars near the supermassive black hole (SMBH) in the Galactic Center (GC) has presented an unexpected challenge to theories of star formation. Kinematic measurements of these stars have revealed a stellar disk structure (with an apparent 20% disk membership) that has provided important clues regarding the origin of these mysterious young stars. However, many of the apparent disk properties are difficult to explain, including the low disk membership fraction and the high eccentricities given the youth of this population. Thus far, all efforts to derive the properties of this disk have made the simplifying assumption that stars at the GC are single stars. Nevertheless, stellar binaries are prevalent in our Galaxy, and recent investigations suggested that they may also be abundant in the Galactic Center. Here, we show that binaries in the disk can largely alter the apparent orbital properties of the disk. The motion of binary members around each other adds a velocity component, which can be comparable to the magnitude of the velocity around the SMBH in the GC. Thus, neglecting the contribution of binaries can significantly vary the inferred stars’ orbital properties. While the disk orientation is unaffected, the apparent disk’s 2D width will be increased to about 11.°2, similar to the observed width. For a population of stars orbiting the SMBH with zero eccentricity, unaccounted for binaries will create a wide apparent eccentricity distribution with an average of 0.23. This is consistent with the observed average eccentricity of the stars’ in the disk. We suggest that this high eccentricity value, which poses a theoretical challenge, may be an artifact of binary stars. Finally, our results suggest that the actual disk membership might be significantly higher than the one inferred by observations that ignore the contribution of binaries, alleviating another theoretical challenge.

A modern study of HD 166734: a massive supergiant system

NASA Astrophysics Data System (ADS)

Mahy, L.; Damerdji, Y.; Gosset, E.; Nitschelm, C.; Eenens, P.; Sana, H.; Klotz, A.

2017-11-01

Aims: HD 166734 is an eccentric eclipsing binary system composed of two supergiant O-type stars, orbiting with a 34.5-day period. In this rare configuration for such stars, the two objects mainly evolve independently, following single-star evolution so far. This system provides a chance to study the individual parameters of two supergiant massive stars and to derive their real masses. Methods: An intensive monitoring was dedicated to HD 166734. We analyzed mid- and high-resolution optical spectra to constrain the orbital parameters of this system. We also studied its light curve for the first time, obtained in the VRI filters. Finally, we disentangled the spectra of the two stars and modeled them with the CMFGEN atmosphere code in order to determine the individual physical parameters. Results: HD 166734 is a O7.5If+O9I(f) binary. We confirm its orbital period but we revise the other orbital parameters. In comparison to what we found in the literature, the system is more eccentric and, now, the hottest and the most luminous component is also the most massive one. The light curve exhibits only one eclipse and its analysis indicates an inclination of 63.0° ± 2.7°. The photometric analysis provides us with a good estimation of the luminosities of the stars, and therefore their exact positions in the Hertzsprung-Russell diagram. The evolutionary and the spectroscopic masses show good agreement with the dynamical masses of 39.5 M⊙ for the primary and 33.5 M⊙ for the secondary, within the uncertainties. The two components are both enriched in helium and in nitrogen and depleted in carbon. In addition, the primary also shows a depletion in oxygen. Their surface abundances are however not different from those derived from single supergiant stars, yielding, for both components, an evolution similar to that of single stars. Based on observations collected at the European Southern Observatory (La Silla, Chile) with FEROS and TAROT and on data collected at the San Pedro Mártir observatory (Mexico).The reduced spectra and the light curves 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/607/A96

A Pulsar and White Dwarf in an Unexpected Orbit

NASA Astrophysics Data System (ADS)

Kohler, Susanna

2016-11-01

Astronomers have discovered a binary system consisting of a low-mass white dwarf and a millisecond pulsar but its eccentric orbit defies all expectations of how such binaries form.Observed orbital periods and binary eccentricities for binary millisecond pulsars. PSR J2234+0511 is the furthest right of the green stars that mark the five known eccentric systems. [Antoniadis et al. 2016]Unusual EccentricityIt would take a low-mass (0.4 solar masses) white dwarf over 100 billion years to form from the evolution of a single star. Since this is longer than the age of the universe, we believe that these lightweights are instead products of binary-star evolution and indeed, we observe many of these stars to still be in binary systems.But the binary evolution that can create a low-mass white dwarf includes a period of mass transfer, in which efficient tidal dissipation damps the systems orbital eccentricity. Because of this, we would expect all systems containing low-mass white dwarfs to have circular orbits.In the past, our observations of low-mass white dwarfmillisecond pulsar binaries have all been consistent with this expectation. But a new detection has thrown a wrench in the works: the unambiguous identification of a low-mass white dwarf thats in an eccentric (e=0.13) orbit with the millisecond pulsar PSR J2234+0511. How could this system have formed?Eliminating Formation ModelsLed by John Antoniadis (Dunlap Institute at University of Toronto), a team of scientists has used newly obtained optical photometry (from the Sloan Digital Sky Survey) and spectroscopy (from the Very Large Telescope in Chile) of the white dwarf to confirm the identification of this system.Antoniadis and collaborators then use measurements of the bodies masses (0.28 and 1.4 solar masses for the white dwarf and pulsar, respectively) and velocities, and constraints on the white dwarfs temperature, radius and surface gravity, to address three proposed models for the formation of this system.The 3D motion of the pulsar (black solid lines; current position marked with diamond) in our galaxy over the past 1.5 Gyr. This motion is typical for low-mass X-ray binary descendants, favoring a binary-evolution model over a 3-body-interaction model. [Antoniadis et al. 2016]In the first model, the eccentric binary was created via adynamic three-body formation channel. This possibility is deemed unlikely, as the white-dwarf properties and all the kinematic properties of the system point to normal binary evolution.In the secondmodel, the binary system gains its high eccentricity after mass transfer ends, when the pulsar progenitor experiences a spontaneous phase transition. The authors explore two options for this: one in which the neutron star implodes into a strange-quark star, and the other in which an over-massive white dwarf suffers a delayed collapse into a neutron star. Both cases are deemed unlikely, because the mass inferred for the pulsar progenitor is not consistent with either model.In the third model, the system forms a circumbinary disk fueled by material escaping the proto-white dwarf. After mass transfer has ended, interactions between the binary and its disk gradually increase the eccentricity of the system, pumping it up to what we observe today. All of the properties of the system measured by Antoniadis and collaborators are thus far consistent with this model.Further observations of this system and systems like it (several others have been detected, though not yet confirmed) will help determine whether binary evolution combined with interactions with a disk can indeed explain the formation of this unexpectedly eccentricsystem.CitationJohn Antoniadis et al 2016 ApJ 830 36. doi:10.3847/0004-637X/830/1/36

Numerical black hole initial data with low eccentricity based on post-Newtonian orbital parameters

DOE Office of Scientific and Technical Information (OSTI.GOV)

Walther, Benny; Bruegmann, Bernd; Mueller, Doreen

2009-06-15

Black hole binaries on noneccentric orbits form an important subclass of gravitational wave sources, but it is a nontrivial issue to construct numerical initial data with minimal initial eccentricity for numerical simulations. We compute post-Newtonian orbital parameters for quasispherical orbits using the method of Buonanno, Chen and Damour, (2006) and examine the resulting eccentricity in numerical simulations. Four different methods are studied resulting from the choice of Taylor-expanded or effective-one-body Hamiltonians, and from two choices for the energy flux. For equal-mass, nonspinning binaries the approach succeeds in obtaining low-eccentricity numerical initial data with an eccentricity of about e=0.002 for rathermore » small initial separations of D > or approx. 10M. The eccentricity increases for unequal masses and for spinning black holes, but remains smaller than that obtained from previous post-Newtonian approaches. The effective-one-body Hamiltonian offers advantages for decreasing initial separation as expected, but in the context of this study also performs significantly better than the Taylor-expanded Hamiltonian for binaries with spin. For mass ratio 4 ratio 1 and vanishing spin, the eccentricity reaches e=0.004. For mass ratio 1 ratio 1 and aligned spins of size 0.85M{sup 2} the eccentricity is about e=0.07 for the Taylor method and e=0.014 for the effective-one-body method.« less

Circumbinary discs: Numerical and physical behaviour

NASA Astrophysics Data System (ADS)

Thun, Daniel; Kley, Wilhelm; Picogna, Giovanni

2017-08-01

Aims: Discs around a central binary system play an important role in star and planet formation and in the evolution of galactic discs. These circumbinary discs are strongly disturbed by the time varying potential of the binary system and display a complex dynamical evolution that is not well understood. Our goal is to investigate the impact of disc and binary parameters on the dynamical aspects of the disc. Methods: We study the evolution of circumbinary discs under the gravitational influence of the binary using two-dimensional hydrodynamical simulations. To distinguish between physical and numerical effects we apply three hydrodynamical codes. First we analyse in detail numerical issues concerning the conditions at the boundaries and grid resolution. We then perform a series of simulations with different binary parameters (eccentricity, mass ratio) and disc parameters (viscosity, aspect ratio) starting from a reference model with Kepler-16 parameters. Results: Concerning the numerical aspects we find that the length of the inner grid radius and the binary semi-major axis must be comparable, with free outflow conditions applied such that mass can flow onto the central binary. A closed inner boundary leads to unstable evolutions. We find that the inner disc turns eccentric and precesses for all investigated physical parameters. The precession rate is slow with periods (Tprec) starting at around 500 binary orbits (Tbin) for high viscosity and a high aspect ratio H/R where the inner hole is smaller and more circular. Reducing α and H/R increases the gap size and Tprec reaches 2500 Tbin. For varying binary mass ratios qbin the gap size remains constant, whereas Tprec decreases with increasing qbin. For varying binary eccentricities ebin we find two separate branches in the gap size and eccentricity diagram. The bifurcation occurs at around ecrit ≈ 0.18 where the gap is smallest with the shortest Tprec. For ebin lower and higher than ecrit, the gap size and Tprec increase. Circular binaries create the most eccentric discs. Movies associated to Figs. 1 and 8 are available at http://www.aanda.org

Structure coefficients for different initial metallicities for use in stellar analysis

NASA Astrophysics Data System (ADS)

Inlek, Gulay; Budding, Edwin; Demircan, Osman

2017-09-01

Internal structure coefficients for zero age Main Sequence (ZAMS) model stars with different initial metallicities are presented. A series of (Eggleton) stellar models with masses between 1-40 M_{⊙} and metallicities Z=0.0001, Z=0.001, Z=0.004, Z=0.01, Z=0.02, and Z=0.03 were used. We have also calculated the same coefficients for a recommended solar metallicity value Z=0.0134 (Asplund et al. in Annu. Rev. Astron. Astrophys. 47:481, 2009). For each model, values of the internal structure constants k2, k3, k4 and related coefficients have been derived by numerically integrating Radau's equation with the (FORTRAN) program RADAU. The (Eggleton) stellar models used come from the ` EZ-Web' compilation of the Dept. of Astronomy, University of Wisconsin, Madison. The calculations follow the procedure given by Inlek and Budding (Astrophys. Space Sci. 342:365, 2012). These new results were compared with others in the literature. We deduce that the current state of theoretical evaluation of structure coefficients is generally in sufficient agreement with data obtained from apsidal advance rates of selected well-observed eccentric eclipsing binary stars at the present time, given the probable errors of the latter. However, new results coming from more precise and extensive data sets in the wake of the Kepler Mission, or similar future surveys, may call for further theoretical specification or refinement. The derivation of structure coefficients from observations of apsidal motion in close eccentric binary systems requires specification of relevant parameters from light curve analysis. A self-consistent treatment then implies inclusion of the structure coefficients within the fitting function of such analysis.

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

NASA Astrophysics Data System (ADS)

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.

A model of V356 Sagittarii. [eclipsing binary star

NASA Technical Reports Server (NTRS)

Wilson, R. E.; Caldwell, C. N.

1978-01-01

It is pointed out that V356 Sgr is an abnormal member of the Algol class of binaries. According to Popper (1955), the primary component is of spectral type B3V and is rotating rapidly, while the secondary is of type A2II and is rotating at least approximately in synchronism with the orbital motion. The system is either semidetached or quite near to being semidetached. The main anomalies are related to the ratio of eclipse depths, the very small reflection effect of the light curves, differences between the duration of the primary and the secondary eclipse, and the unusual characteristics of the primary eclipse. It is concluded that the lack of agreement between theory and observation can be due only to an important attribute of the binary which has not yet been incorporated into the theory. The peculiarities can most reasonably be explained in terms of a geometrically and optically thick disk which surrounds the primary component.

VizieR Online Data Catalog: OGLE II SMC eclipsing binaries (Wyrzykowski+, 2004)

NASA Astrophysics Data System (ADS)

Wyrzykowski, L.; Udalski, A.; Kubiak, M.; Szymanski, M. K.; Zebrun, K.; Soszinski, I.; Wozniak, P. R.; Pietrzynski, G.; Szewczyk, O.

2009-03-01

We present new version of the OGLE-II catalog of eclipsing binary stars detected in the Small Magellanic Cloud, based on Difference Image Analysis catalog of variable stars in the Magellanic Clouds containing data collected from 1997 to 2000. We found 1351 eclipsing binary stars in the central 2.4 square degree area of the SMC. 455 stars are newly discovered objects, not found in the previous release of the catalog. The eclipsing objects were selected with the automatic search algorithm based on the artificial neural network. The full catalog with individual photometry is accessible from the OGLE INTERNET archive, at ftp://sirius.astrouw.edu.pl/ogle/ogle2/var_stars/smc/ecl . Regular observations of the SMC fields started on June 26, 1997 and covered about 2.4 square degrees of central parts of the SMC. Reductions of the photometric data collected up to the end of May 2000 were performed with the Difference Image Analysis (DIA) package. (1 data file).

Atmospheric, Orbital and Secondary Eclipse Analysis of HAT-P-30-WASP-51b

NASA Astrophysics Data System (ADS)

Foster, Andrew S.; Harrington, Joseph; Cubillos, Patricio; Blecic, Jasmina; Challener, Ryan; Foster, Austin James; Garland, Justin

2016-01-01

HAT-P-30-WASP-51b is a hot-Jupiter planet that orbits an F star every 2.8106 days at a distance of 0.0419 AU. Using the Spitzer Space Telescope in 2012 (Spitzer Program Number 70084) we observed two secondary eclipses of the planet, one in the 3.6 μm channel on 3 January and one in the 4.5 μm channel on 17 January. We present eclipse-depth measurements of 0.00163±0.0001 and 0.00146±0.00013 and we esitmate the infrared brightness temperatures to be 1900±50 and 1600±60 for these two channels, respectively, from an analysis using our Photometry for Orbits, Eclipses, and Transits (POET) pipeline. We also refine its orbit using our own secondary-eclipse measurements in combination with radial-velocity and transit observations from both professional and amateur observers. The most notable result from this orbital analysis is a detection of eccentricity in the planet's orbit. Using only the phase of our secondary eclipses, we can constrain ecosw to a minimum of 0.0084±0.0004, a 20 sigma detection of one component of the orbit's eccentricity that is independent of the effects that stellar tides have on radial velocity data. We then characterize its atmosphere's temperature- pressure profile and molecular abundances using our Bayesian Atmospheric Radiative Transfer code (BART). 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 NNX12AI69G and NASA Astrophysics Data Analysis Program grant NNX13AF38G. J. Blecic holds a NASA Earth and Space Sciences Fellowship.

Atmospheric, Orbital and Eclipse Depth Analysis of the Hot Jupiter HAT-P-30-WASP-51b

NASA Astrophysics Data System (ADS)

Foster, Andrew S.; Harrington, Joseph; Cubillos, Patricio; Blecic, Jasmina; Foster, A. J.; Challener, Ryan; Garland, Justin

2015-11-01

HAT-P-30-WASP-51b is a hot-Jupiter planet that orbits an F star every 2.8106 days at a distance of 0.0419 AU. Using the Spitzer Space Telescope in 2012 (Spitzer Program Number 70084) we observed two secondary eclipses of the planet, one in the 3.6 μm channel on 3 January and one in the 4.5 μm channel on 17 January. We present eclipse-depth measurements of 0.00163 ± 0.0001 and 0.00146 ± 0.00013 and we esitmate the infrared brightness temperatures to be 1900 ± 50 and 1600 ± 60 for these two channels, respectively, from an analysis using our Photometry for Orbits, Eclipses, and Transits (POET) pipeline. We also refine its orbit using our own secondary-eclipse measurements in combination with radial-velocity and transit observations from both professional and amateur observers. The most notable result from this orbital analysis is a detection of eccentricity in the planet's orbit. Using only the phase of our secondary eclipses, we can constrain ecosw to a minimum of 0.0084 ± 0.0004, a 20 sigma detection of one component of the orbit's eccentricity that is independent of the effects that stellar tides have on radial velocity data. We then characterize its atmosphere's temperature- pressure profile and molecular abundances using our Bayesian Atmospheric Radiative Transfer code (BART). 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 NNX12AI69G and NASA Astrophysics Data Analysis Program grant NNX13AF38G. J. Blecic holds a NASA Earth and Space Science Fellowship.

Planetary Systems Dynamics Eccentric patterns in debris disks & Planetary migration in binary systems

NASA Astrophysics Data System (ADS)

Faramaz, V.; Beust, H.; Augereau, J.-C.; Bonsor, A.; Thébault, P.; Wu, Y.; Marshall, J. P.; del Burgo, C.; Ertel, S.; Eiroa, C.; Montesinos, B.; Mora, A.

2014-01-01

We present some highlights of two ongoing investigations that deal with the dynamics of planetary systems. Firstly, until recently, observed eccentric patterns in debris disks were found in young systems. However recent observations of Gyr-old eccentric debris disks leads to question the survival timescale of this type of asymmetry. One such disk was recently observed in the far-IR by the Herschel Space Observatory around ζ2 Reticuli. Secondly, as a binary companion orbits a circumprimary disk, it creates regions where planet formation is strongly handicapped. However, some planets were detected in this zone in tight binary systems (γ Cep, HD 196885). We aim to determine whether a binary companion can affect migration such that planets are brought in these regions and focus in particular on the planetesimal-driven migration mechanism.

Primordial main equence binary stars in the globular cluster M71

NASA Technical Reports Server (NTRS)

Yan, Lin; Mateo, Mario

1994-01-01

We report the identification of five short-period variables near the center of the metal-rich globular cluster M71. Our observations consist of multiepoch VI charge coupled device (CCD) images centered on the cluster and covering a 6.3 min x 6.3 min field. Four of these variables are contact eclipsing binaries with periods between 0.35 and 0.41 days; one is a detached or semidetached eclipsing binary with a period of 0.56 days. Two of the variables were first identified as possible eclipsing binaries in an earlier survey by Hodder et al. (1992). We have used a variety of arguments to conclude that all five binary stars are probable members of M71, a result that is consistent with the low number (0.15) of short-period field binaries expected along this line of sight. Based on a simple model of how contact binaries evolve from initially detached binaries, we have determined a lower limit of 1.3% on the frequency of primordial binaries in M71 with initial orbital periods in the range 2.5 - 5 days. This implies that the overall primordial binary frequency, f, is 22(sup +26)(sub -12)% assuming df/d log P = const ( the 'flat' distribution), or f = 57(sup +15)(sub -8)% for df/d log P = 0.032 log P + const as observed for G-dwarf binaries in the solar neighborhood (the 'sloped' distribution). Both estimates of f correspond to binaries with initial periods shorter than 800 yr since any longer-period binaries would have been disrupted over the lifetime of the cluster. Our short-period binary frequency is in excellent agreement with the observed frequency of red-giant binaries observed in globulars if we adopt the flat distribution. For the sloped distribution, our results significantly overestimate the number of red-giant binaries. All of the short-period M71 binaries lie within 1 mag of the luminosity of the cluster turnoff in the color-magnitude diagram despite the fact we should have easily detected similar eclipsing binaries 2 - 2.5 mag fainter than this. We discuss the implications of this on our estimates of the binary frequency in M71 and on the formation of blue stragglers.

Dynamical tides in highly eccentric binaries: chaos, dissipation, and quasi-steady state

NASA Astrophysics Data System (ADS)

Vick, Michelle; Lai, Dong

2018-05-01

Highly eccentric binary systems appear in many astrophysical contexts, ranging from tidal capture in dense star clusters, precursors of stellar disruption by massive black holes, to high-eccentricity migration of giant planets. In a highly eccentric binary, the tidal potential of one body can excite oscillatory modes in the other during a pericentre passage, resulting in energy exchange between the modes and the binary orbit. These modes exhibit one of three behaviours over multiple passages: low-amplitude oscillations, large-amplitude oscillations corresponding to a resonance between the orbital frequency and the mode frequency, and chaotic growth, with the mode energy reaching a level comparable to the orbital binding energy. We study these phenomena with an iterative map that includes mode dissipation, fully exploring how the mode evolution depends on the orbital and mode properties of the system. The dissipation of mode energy drives the system towards a quasi-steady state, with gradual orbital decay punctuated by resonances. We quantify the quasi-steady state and the long-term evolution of the system. A newly captured star around a black hole can experience significant orbital decay and heating due to the chaotic growth of the mode amplitude and dissipation. A giant planet pushed into a high-eccentricity orbit may experience a similar effect and become a hot or warm Jupiter.

V380 Dra: New short-period totally eclipsing active binary

NASA Astrophysics Data System (ADS)

Özdarcan, O.

2014-02-01

In this study, first complete and standard BVR light curves and photometric analysis of the eclipsing binary system V380 Dra are presented. Photometric analysis result indicates that the system has components which are cool main sequence stars. In light and color curves, remarkable asymmetry is observed, especially after secondary minimum, which is believed to be a result of chromospheric activity in one or both components. O-C diagram of available small number of eclipse times, together with new eclipse timings in this work, exhibits no significant variation. Preliminary light curve solution shows that the secondary minimum is total eclipse. By using the advantage of total eclipse and mass-luminosity relation, it is found that the system has a possible mass ratio of q = 0.81. First estimation of masses and radii of primary and secondary components are M1 = 0.77 M⊙,M2 = 0.62 M⊙ and R1 = 0.93 R⊙,R2 = 0.77 R⊙, respectively.

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

NASA Astrophysics Data System (ADS)

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.

A computer program for modeling non-spherical eclipsing binary star systems

NASA Technical Reports Server (NTRS)

Wood, D. B.

1972-01-01

The accurate analysis of eclipsing binary light curves is fundamental to obtaining information on the physical properties of stars. The model described accounts for the important geometric and photometric distortions such as rotational and tidal distortion, gravity brightening, and reflection effect. This permits a more accurate analysis of interacting eclipsing star systems. The model is designed to be useful to anyone with moderate computing resources. The programs, written in FORTRAN 4 for the IBM 360, consume about 80k bytes of core. The FORTRAN program listings are provided, and the computational aspects are described in some detail.

Search for Pulsating Stars in the Open Cluster NGC 1502

NASA Astrophysics Data System (ADS)

Stęślicki, M.

2006-04-01

We present results of a variability search in the field of the young open cluster NGC 1502. We confirm that a beta Cephei suspect WEBDA 26 is indeed pulsating with a period of 0.09612 d and semi-amplitude of about 3 mmag in V. A new VI light curve of the bright eclipsing binary and cluster member SZ Cam was obtained. In addition, we found two new variable stars. One is an interesting eclipsing binary showing total eclipses, which can be used to derive the distance to the cluster once radial velocities of the components will be obtained.

MM Herculis - An eclipsing binary of the RS CVn

NASA Technical Reports Server (NTRS)

Sowell, J. R.; Hall, D. S.; Henry, G. W.; Burke, E. W., Jr.; Milone, E. F.

1983-01-01

V, B and U differential photoelectric photometry has been obtained for the RS Canum Venaticorum-class eclipsing binary star MM Her, with the light outside the eclipse being Fourier-analyzed to study wave migration and amplitude. These, together with the mean light level of the system, have been monitored from 1976 through 1980. Observations within the eclipse have revealed eclipses to be partial, rather than total as previously thought. The geometric elements of the presently rectified light curve are forced on the pre-1980 light curves and found to be compatible. With these elements, and previously obtained double line radial velocity curves, new absolute dimensions of 1.18 solar masses and 1.58 solar radii are calculated for the hotter star and 1.27 solar masses and 2.83 solar radii for the cooler star. The plotting of color indices on the color-color curve indicates G2V and K2IV spectral types.

A new study of the interacting binary star V356 Sgr

NASA Technical Reports Server (NTRS)

Polidan, R. S.

1988-01-01

Results on V356 Sgr from IUE and Voyager ultraviolet (500 to 3200 A) observations obtained in 1986 and 1987, primarily during 2 total eclipses are presented. The eclipse of Aug. 15, 1986 was fully covered with IUE low dispersion images and 9 hr of Voyager UVS data. The eclipse of Mar. 25, 1987 was covered with IUE low dispersion images and 1 high dispersion SWP image. During both eclipses the total strength of the emission lines is found to be invariant. An uneclipsed UV continuum is detected at wavelengths shorter than 1500 A. The high dispersion SWP spectrum reveals that the emission lines are extremely broad, almost symmetrical emissions with weak, slightly blue shifted absorption components. No evidence of carbon, C I, C II, C III, or C IV, is seen in the emission or absorption spectrum of V356 Sgr in eclipse. Models for this binary system are presented.

Vulcan Identification of Eclipsing Binaries in the Kepler Field of View

NASA Astrophysics Data System (ADS)

Mjaseth, Kimberly; Batalha, N.; Borucki, W.; Caldwell, D.; Latham, D.; Martin, K. R.; Rabbette, M.; Witteborn, F.

2007-05-01

We report the discovery of 236 new eclipsing binary stars located in and around the field of view of the Kepler Mission. The binaries were identified from photometric light curves from the Vulcan exoplanet transit survey. The Vulcan camera is comprised of a modest aperture (10cm) f/2.8 Canon lens focusing a 7° x 7° field of view onto a 4096 x 4096 Kodak CCD. The system yields an hour-to-hour relative precision of 0.003 on 12th magnitude stars and saturates at 9th magnitude. The binaries have magnitudes in the range of 9.5 < V < 13.5 and periods ranging from 0.5 to 13 days. The milli-magnitude photometric precision allows detection of transits as shallow as 1%. The catalog contains a total of 273 eclipsing binary stars, including detached systems (high and low mass ratio), contact binaries, and triple systems. We present the derived orbital/transit properties, light curves, and stellar properties for selected targets. In addition, we summarize the results of radial velocity follow-up work. Support for this work came from NASA's Discovery Program and NASA's Origins of the Solar System Program.

Linear analysis of the evolution of nearly polar low-mass circumbinary discs

NASA Astrophysics Data System (ADS)

Lubow, Stephen H.; Martin, Rebecca G.

2018-01-01

In a recent paper Martin & Lubow showed through simulations that an initially tilted disc around an eccentric binary can evolve to polar alignment in which the disc lies perpendicular to the binary orbital plane. We apply linear theory to show both analytically and numerically that a nearly polar aligned low-mass circumbinary disc evolves to polar alignment and determine the alignment time-scale. Significant disc evolution towards the polar state around moderately eccentric binaries can occur for typical protostellar disc parameters in less than a typical disc lifetime for binaries with orbital periods of order 100 yr or less. Resonant torques are much less effective at truncating the inner parts of circumbinary polar discs than the inner parts of coplanar discs. For polar discs, they vanish for a binary eccentricity of unity. The results agree with the simulations in showing that discs can evolve to a polar state. Circumbinary planets may then form in such discs and reside on polar orbits.

VizieR Online Data Catalog: ASAS, NSVS, and LINEAR detached eclipsing binaries (Lee, 2015)

NASA Astrophysics Data System (ADS)

Lee, C.-H.

2016-04-01

We follow the approach of Devor et al. (2008AJ....135..850D, Cat. J/AJ/135/850) to analyse the LC from ASAS (Pojmanski et al., Cat. II/264, NSVS (Wozniak et al., 2004AJ....127.2436W, and LINEAR (Palaversa et al., Cat. J/AJ/146/101) and extract the physical properties of the eclipsing binaries. (3 data files).

New spectroscopic binary companions of giant stars and updated metallicity distribution for binary systems

NASA Astrophysics Data System (ADS)

Bluhm, P.; Jones, M. I.; Vanzi, L.; Soto, M. G.; Vos, J.; Wittenmyer, R. A.; Drass, H.; Jenkins, J. S.; Olivares, F.; Mennickent, R. E.; Vučković, M.; Rojo, P.; Melo, C. H. F.

2016-10-01

We report the discovery of 24 spectroscopic binary companions to giant stars. We fully constrain the orbital solution for 6 of these systems. We cannot unambiguously derive the orbital elements for the remaining stars because the phase coverage is incomplete. Of these stars, 6 present radial velocity trends that are compatible with long-period brown dwarf companions. The orbital solutions of the 24 binary systems indicate that these giant binary systems have a wide range in orbital periods, eccentricities, and companion masses. For the binaries with restricted orbital solutions, we find a range of orbital periods of between ~97-1600 days and eccentricities of between ~0.1-0.4. In addition, we studied the metallicity distribution of single and binary giant stars. We computed the metallicity of a total of 395 evolved stars, 59 of wich are in binary systems. We find a flat distribution for these binary stars and therefore conclude that stellar binary systems, and potentially brown dwarfs, have a different formation mechanism than planets. This result is confirmed by recent works showing that extrasolar planets orbiting giants are more frequent around metal-rich stars. Finally, we investigate the eccentricity as a function of the orbital period. We analyzed a total of 130 spectroscopic binaries, including those presented here and systems from the literature. We find that most of the binary stars with periods ≲30 days have circular orbits, while at longer orbital periods we observe a wide spread in their eccentricities. Based on observations collected at La Silla - Paranal Observatory under programs IDs IDs 085.C-0557, 087.C.0476, 089.C-0524, 090.C-0345, 096.A-9020 and through the Chilean Telescope Time under programs IDs CN2012A-73, CN2012B-47, CN2013A-111, CN2013B-51, CN2014A-52 and CN2015A-48.

Eccentric Black Hole Gravitational-wave Capture Sources in Galactic Nuclei: Distribution of Binary Parameters

NASA Astrophysics Data System (ADS)

Gondán, László; Kocsis, Bence; Raffai, Péter; Frei, Zsolt

2018-06-01

Mergers of binary black holes on eccentric orbits are among the targets for second-generation ground-based gravitational-wave detectors. These sources may commonly form in galactic nuclei due to gravitational-wave emission during close flyby events of single objects. We determine the distributions of initial orbital parameters for a population of these gravitational-wave sources. Our results show that the initial dimensionless pericenter distance systematically decreases with the binary component masses and the mass of the central supermassive black hole, and its distribution depends sensitively on the highest possible black hole mass in the nuclear star cluster. For a multi-mass black hole population with masses between 5 {M}ȯ and 80 {M}ȯ , we find that between ∼43–69% (68–94%) of 30 {M}ȯ –30 {M}ȯ (10 M ⊙–10 M ⊙) sources have an eccentricity greater than 0.1 when the gravitational-wave signal reaches 10 Hz, but less than ∼10% of the sources with binary component masses less than 30 {M}ȯ remain eccentric at this level near the last stable orbit (LSO). The eccentricity at LSO is typically between 0.005–0.05 for the lower-mass BHs, and 0.1–0.2 for the highest-mass BHs. Thus, due to the limited low-frequency sensitivity, the six currently known quasicircular LIGO/Virgo sources could still be compatible with this originally highly eccentric source population. However, at the design sensitivity of these instruments, the measurement of the eccentricity and mass distribution of merger events may be a useful diagnostic to identify the fraction of GW sources formed in this channel.

Period changes of the sample of eclipsing binaries with active chromospheres

NASA Astrophysics Data System (ADS)

Jableka, D.; Zola, S.; Zakrzewski, B.; Szymanski, T.; Kuzmicz, A.; de Villiers, S. N.; Zejda, M.; Koziel-Wierzbowska, D.

2012-11-01

In this work we present results derived from analysis of the O-C behaviour of ten eclipsing binary systems: AR Lac, CG Cyg, HP Aur, MM Her, RS CVn, RT And, SV Cam, V471 Tau, WW Dra and CF Tuc. It was proved on the basis of moments of minima compiled from the literature and new ones determined from recent observations, that these binaries show long term (19-91 years) modulations of their orbital periods, clearly visible in their O-C diagrams. Two possible explanations for this effect are considered: (1) the light-travel time effect due to the presence of a third body orbiting the eclipsing systems; (2) the Applegate mechanism predicting period modulation by changes in the distribution of angular momentum as a star goes through its activity cycles. It was found that in the case of four systems the existence of a third star, orbiting the binary, is a more plausible explanation of observations.

The Surface Brightness-color Relations Based on Eclipsing Binary Stars: Toward Precision Better than 1% in Angular Diameter Predictions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Graczyk, Dariusz; Gieren, Wolfgang; Konorski, Piotr

In this study we investigate the calibration of surface brightness–color (SBC) relations based solely on eclipsing binary stars. We selected a sample of 35 detached eclipsing binaries with trigonometric parallaxes from Gaia DR1 or Hipparcos whose absolute dimensions are known with an accuracy better than 3% and that lie within 0.3 kpc from the Sun. For the purpose of this study, we used mostly homogeneous optical and near-infrared photometry based on the Tycho-2 and 2MASS catalogs. We derived geometric angular diameters for all stars in our sample with a precision better than 10%, and for 11 of them with amore » precision better than 2%. The precision of individual angular diameters of the eclipsing binary components is currently limited by the precision of the geometric distances (∼5% on average). However, by using a subsample of systems with the best agreement between their geometric and photometric distances, we derived the precise SBC relations based only on eclipsing binary stars. These relations have precisions that are comparable to the best available SBC relations based on interferometric angular diameters, and they are fully consistent with them. With very precise Gaia parallaxes becoming available in the near future, angular diameters with a precision better than 1% will be abundant. At that point, the main uncertainty in the total error budget of the SBC relations will come from transformations between different photometric systems, disentangling of component magnitudes, and for hot OB stars, the main uncertainty will come from the interstellar extinction determination. We argue that all these issues can be overcome with modern high-quality data and conclude that a precision better than 1% is entirely feasible.« less

The EB factory project. I. A fast, neural-net-based, general purpose light curve classifier optimized for eclipsing binaries

DOE Office of Scientific and Technical Information (OSTI.GOV)

Paegert, Martin; Stassun, Keivan G.; Burger, Dan M.

2014-08-01

We describe a new neural-net-based light curve classifier and provide it with documentation as a ready-to-use tool for the community. While optimized for identification and classification of eclipsing binary stars, the classifier is general purpose, and has been developed for speed in the context of upcoming massive surveys such as the Large Synoptic Survey Telescope. A challenge for classifiers in the context of neural-net training and massive data sets is to minimize the number of parameters required to describe each light curve. We show that a simple and fast geometric representation that encodes the overall light curve shape, together withmore » a chi-square parameter to capture higher-order morphology information results in efficient yet robust light curve classification, especially for eclipsing binaries. Testing the classifier on the ASAS light curve database, we achieve a retrieval rate of 98% and a false-positive rate of 2% for eclipsing binaries. We achieve similarly high retrieval rates for most other periodic variable-star classes, including RR Lyrae, Mira, and delta Scuti. However, the classifier currently has difficulty discriminating between different sub-classes of eclipsing binaries, and suffers a relatively low (∼60%) retrieval rate for multi-mode delta Cepheid stars. We find that it is imperative to train the classifier's neural network with exemplars that include the full range of light curve quality to which the classifier will be expected to perform; the classifier performs well on noisy light curves only when trained with noisy exemplars. The classifier source code, ancillary programs, a trained neural net, and a guide for use, are provided.« less

On the Existence of t-Identifying Codes in Undirected De Bruijn Networks

DTIC Science & Technology

2015-08-04

remaining cases remain open. Additionally, we show that the eccentricity of the undirected non-binary de Bruijn graph is n. 15. SUBJECT TERMS...Additionally, we show that the eccentricity of the undirected non-binary de Bruijn graph is n. 1 Introduction and Background Let x ∈ V (G), and...we must have d(y, x) = n + 2. In other words, Theorem 2.5 tells us the eccentricity of every node in the graph B(d, n) is n for d ≥ 3, and so the

PG0027 + 260 - An example of a class of cataclysmic binaries with mysterious, but consistent, behavior

NASA Technical Reports Server (NTRS)

Thorstensen, John R.; Ringwald, F. A.; Wade, Richard A.; Schmidt, Gary D.; Norsworthy, Jane E.

1991-01-01

This paper reports extensive optical observations on the PG0027 + 260 binary, carried out on August 1984 with the 1.3 McGraw-Hill telescope and Mark II spectrometer at Michigan-Dartmouth-MIT Observatory on Kitt Peak. It is shown that this object is an eclipsing novalike variable with an orbital period of 3.51 hr. The PG0027 + 260 displays several unexplained phenomena which are remarkably similar to those of the SW Sex, DW UMa, and V1315 Aql, which are eclipsing novalike stars with periods between 3 and 4 hrs. The eclipse of the PG0027 + 260 is modeled, and it is shown that, while the mean eclipse light curve is easy to match, there is no simple explanation for the variable depth.

Optical polarization observations of epsilon Aurigae during the 2009-2011 eclipse

NASA Astrophysics Data System (ADS)

Henson, Gary D.; Burdette, John; Gray, Sharon

2012-05-01

Polarization observations of the unique eclipsing binary, Epsilon Aurigae, are being carried out using a new dual beam imaging polarimeter on the 0.36m telescope of the Harry D. Powell Observatory. This bright binary system has a 27.1 year period with an eclipse duration of nearly two years. The primary is known to be a pulsating F0 supergiant with the secondary a large and essentially opaque disk. We report here on the characteristics of the polarimeter and on the status of V-band observations that are being obtained to better understand the system's geometry and the nature of its two components. In particular, the characteristics of the secondary disk remain a puzzle. Results are compared to polarization observations from the 1982-1984 eclipse.

Implications of the Secondary Eclipse of Exoplanet HAT-P-11b

NASA Technical Reports Server (NTRS)

Barry, Richard K.; Deming, L. D.; Bakos, G.; Harrington, J.; Madhusudhan, N.; Noyes, R.; Seager, S.

2010-01-01

We observed exoplanet HAT-P-11b and have successfully detected its secondary eclipse. We conducted observations using the Spitzer Space Telescope in the post-cryo mission at 3.6 microns for a period of 22 hours centered on the anticipated secondary eclipse time, to detect the eclipse and determine its phase. Having detected the secondary eclipse, we are at present making a more focused series of observations in both the 3.6 and 4.5 micron bands to fully characterize it. HAT-P-11b is one of only two known exo-Neptunes and has a period of 4.8878 days, radius of 0.422 RJ, mass of 0.081 MJ and semi-major axis 0.053 AU. Measurements of the secondary eclipse will serve to clarify two key issues; 1) the planetary brightness temperature and the nature of its atmosphere, and 2) the eccentricity of its orbit, with implications for its dynamical evolution. We discuss implications of these observations.

Photometric and Spectroscopic Analysis for the Determination of Physical Parameters of an Eclipsing Binary Star System

NASA Astrophysics Data System (ADS)

Reid, Piper

2013-01-01

A binary star system is a pair of stars that are bound together by gravity. Most of the stars that we see in the night sky are members of multiple star systems. A system of stars where one star passes in front of the other (as observed from Earth) on a periodic basis is called an eclipsing binary. Eclipsing binaries can have very short rotational periods and in all cases these pairs of stars are so far away that they can only be resolved from Earth as a single point of light. The interaction of the two stars serves to produce physical phenomena that can be observed and used to study stellar properties. By careful data collection and analysis is it possible for an amateur astronomer using commercial, low cost equipment (including a home built spectroscope) to gather photometric (brightness versus time) and spectroscopic (brightness versus wavelength) data, analyze the data, and calculate the physical properties of a binary star system? Using a CCD camera, tracking mount and telescope photometric data of BB Pegasi was collected and a light curve produced. 57 Cygni was also studied using a spectroscope, tracking mount and telescope to prove that Doppler shift of Hydrogen Balmer absorption lines can be used to determine radial velocity. The orbital period, orbital velocity, radius of each star, separation of the two stars and mass of each star was calculated for the eclipsing binary BB Pegasi using photometric and spectroscopic data and Kepler’s 3rd Law. These data were then compared to published data. By careful use of consumer grade astronomical equipment it is possible for an amateur astronomer to determine an array of physical parameters of a distant binary star system from a suburban setting.

Pervasive orbital eccentricities dictate the habitability of extrasolar earths.

PubMed

Kita, Ryosuke; Rasio, Frederic; Takeda, Genya

2010-09-01

The long-term habitability of Earth-like planets requires low orbital eccentricities. A secular perturbation from a distant stellar companion is a very important mechanism in exciting planetary eccentricities, as many of the extrasolar planetary systems are associated with stellar companions. Although the orbital evolution of an Earth-like planet in a stellar binary system is well understood, the effect of a binary perturbation on a more realistic system containing additional gas-giant planets has been very little studied. Here, we provide analytic criteria confirmed by a large ensemble of numerical integrations that identify the initial orbital parameters leading to eccentric orbits. We show that an extrasolar earth is likely to experience a broad range of orbital evolution dictated by the location of a gas-giant planet, which necessitates more focused studies on the effect of eccentricity on the potential for life.

Infrared radiation from an extrasolar planet.

PubMed

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

2005-04-07

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

Einstein@Home Discovery of a PALFA Millisecond Pulsar in an Eccentric Binary Orbit

NASA Astrophysics Data System (ADS)

Knispel, B.; Lyne, A. G.; Stappers, B. W.; Freire, P. C. C.; Lazarus, P.; Allen, B.; Aulbert, C.; Bock, O.; Bogdanov, S.; Brazier, A.; Camilo, F.; Cardoso, F.; Chatterjee, S.; Cordes, J. M.; Crawford, F.; Deneva, J. S.; Eggenstein, H.-B.; Fehrmann, H.; Ferdman, R.; Hessels, J. W. T.; Jenet, F. A.; Karako-Argaman, C.; Kaspi, V. M.; van Leeuwen, J.; Lorimer, D. R.; Lynch, R.; Machenschalk, B.; Madsen, E.; McLaughlin, M. A.; Patel, C.; Ransom, S. M.; Scholz, P.; Siemens, X.; Spitler, L. G.; Stairs, I. H.; Stovall, K.; Swiggum, J. K.; Venkataraman, A.; Wharton, R. S.; Zhu, W. W.

2015-06-01

We report the discovery of the millisecond pulsar (MSP) PSR J1950+2414 (P = 4.3 ms) in a binary system with an eccentric (e = 0.08) 22 day orbit in Pulsar Arecibo L-band Feed Array survey observations with the Arecibo telescope. Its companion star has a median mass of 0.3 M⊙ and is most likely a white dwarf (WD). Fully recycled MSPs like this one are thought to be old neutron stars spun-up by mass transfer from a companion star. This process should circularize the orbit, as is observed for the vast majority of binary MSPs, which predominantly have orbital eccentricities e < 0.001. However, four recently discovered binary MSPs have orbits with 0. 027 < e < 0.44; PSR J1950+2414 is the fifth such system to be discovered. The upper limits for its intrinsic spin period derivative and inferred surface magnetic field strength are comparable to those of the general MSP population. The large eccentricities are incompatible with the predictions of the standard recycling scenario: something unusual happened during their evolution. Proposed scenarios are (a) initial evolution of the pulsar in a triple system which became dynamically unstable, (b) origin in an exchange encounter in an environment with high stellar density, (c) rotationally delayed accretion-induced collapse of a super-Chandrasekhar WD, and (d) dynamical interaction of the binary with a circumbinary disk. We compare the properties of all five known eccentric MSPs with the predictions of these formation channels. Future measurements of the masses and proper motion might allow us to firmly exclude some of the proposed formation scenarios.

Observations of candidate oscillating eclipsing binaries and two newly discovered pulsating variables

NASA Astrophysics Data System (ADS)

Liakos, A.; Niarchos, P.

2009-03-01

CCD observations of 24 eclipsing binary systems with spectral types ranging between A0-F0, candidate for containing pulsating components, were obtained. Appropriate exposure times in one or more photometric filters were used so that short-periodic pulsations could be detected. Their light curves were analyzed using the Period04 software in order to search for pulsational behaviour. Two new variable stars, namely GSC 2673-1583 and GSC 3641-0359, were discov- ered as by-product during the observations of eclipsing variables. The Fourier analysis of the observations of each star, the dominant pulsation frequencies and the derived frequency spectra are also presented.

MOST: A Powerful Tool to Reveal the True Nature of the Mysterious Dust-Forming Wolf-Rayet Binary CV Ser

NASA Astrophysics Data System (ADS)

David-Uraz, A.; Moffat, A. F. J.; Chené, A.-N.; MOST Collaboration

2012-12-01

The WR + O binary CV Ser has been a source of mystery since it was shown that its atmospheric eclipses change with time over decades, in addition to its sporadic dust production. However, the first high-precision time-dependent photometric observations obtained with the MOST space telescope in 2009 show two consecutive eclipses over the 29 day orbit, with varying depths. A subsequent MOST run in 2010 showed a somewhat asymmetric eclipse profile. Parallel optical spectroscopy was obtained from the Observatoire du Mont-Mégantic (2009 and 2010) and from the Dominion Astrophysical Observatory (2009).

Photometric study of the eclipsing binary GR Bootis

NASA Astrophysics Data System (ADS)

Zhang, Z. L.; Zhang, Y. P.; Fu, J. N.; Xue, H. F.

2016-07-01

We present CCD photometry and low-resolution spectra of the eclipsing binary GR Boo. A new ephemeris is determined based on all the available times of the minimum light. The period analysis reveals that the orbital period is decreasing with a rate of dP / dt = - 2.05 ×10-10 d yr-1 . A photometric analysis for the obtained light curves is performed with the Wilson-Devinney Differential Correction program for the first time. The photometric solutions confirm the W UMa-type nature of the binary system. The mass ratio turns out to be q = 0.985 ± 0.001 . The evolutionary status and physical nature of the binary system are briefly discussed.

A New Binary Star System of EW Type in Draco: GSC 03905-01870

NASA Astrophysics Data System (ADS)

Barquin, S.

2018-05-01

Discovery of a new binary star system (GSC 03905-01870 = USNO-B1.0 1431-0327922 = UCAC4 716-059522) in the Draco constellation is presented. It was discovered during a search for previously unreported eclipsing binary stars through the ASAS-SN database. The shape of the light curve and its characteristics (period of 0.428988+-0.000001 d, amplitude of 0.34+-0.02 V Mag, primary minimum epoch HJD 2457994.2756+-0.0002) indicates that the new variable star is an eclipsing binary of W Ursae Majoris type. I registered this variable star in The International Variable Star Index (VSX), its AAVSO UID is 000-BMP-891.

Sub-1% accuracy in fundamental stellar parameters from triply eclipsing systems

NASA Astrophysics Data System (ADS)

Prsa, Andrej

The current state-of-the-art level of accuracy in fundamental stellar parameters from eclipsing binary stars is 2-3%. Here we propose to use eclipsing triple stars to reduce the error bars by an entire order of magnitude, i.e. to 0.2-0.3%. This can be done because a presence of the third component breaks most of the degeneracy inherent in binary systems between the inclination and stellar sizes. We detail the feasibility arguments and foresee that these results will provide exceptional benchmark objects for stringent tests of stellar evolution and population models. The formation channel of close binary stars (with separations of several stellar radii) is a matter of debate. It is clear that close binaries cannot form in situ because (1) the physical radius of a star shrinks by a large factor between birth and the main sequence, yet many main-sequence stars have companions orbiting at a distance of only a few stellar radii, and (2) in current theories of planet formation, the region within 0.1 AU of a protostar is too hot and rarefied for a Jupiter-mass planet to form, yet many hot jupiters are observed at such distances. Current theories of dynamic orbital evolution attribute orbital shrinking to Kozai cycles and tidal friction, which are long-lasting, perturbative effects that take Gyrs to shrink orbits by 1-2 orders of magnitude. This implies that, if a binary star system has a tertiary companion, it will be in a hierarchical structure, and any disruptive orbital encounters should be exceedingly rare after a certain period. The Kepler satellite observed continuously over 2800 eclipsing binary stars over 4 years of its mission lifetime. The ultra-high precision photometry and essentially uninterrupted time coverage enables us to time the eclipses to a 6 second precision. Because of the well understood physics that governs the orbital motion of two bodies around the center of mass, the expected times of eclipses can be predicted to a fraction of a second. When other physical processes interplay, such as apsidal motion, mass transfer or third body interactions, the times of eclipses deviate from predictions: they either come early or late. These deviations are called eclipse timing variations (ETVs) and can range from a few seconds to a few hours. Our team measured ETVs for the entire Kepler data-set of eclipsing binaries and found 516 that demonstrate significant deviations. Of those, 16 show strong interactions between the binary system and the tertiary component that significantly affects the binary orbit within a single encounter. This observed rate of dynamical perturbation events is unexpectedly high and at odds with current theories. We propose to study these objects in great detail: (1) to apply a developed photodynamical code to model multiple body interactions; (2) to fully solve orbital dynamics of these interacting bodies using all available Kepler data, deriving masses of all objects to better than 1%; (3) to measure the occurrence rate of strong orbital interactions in multiple systems and compare it to the predicted rates; (4) to hypothesize and simulate additional evolution channels that could potentially lead to such a high occurrence rate of disruptive events; and (5) to integrate these systems over time and test whether this dynamic evolution can cause efficient orbital tightening and the creation of short period binaries. The team consists of a PI who has experience with Kepler satellite's idiosyncrasies, two postdoctoral fellows, one graduate student, and six undergraduate students that will invest their summer months to learn about multiple body interactions. The proposed study has far-reaching research goals in stellar and planetary science astrophysics, a strong educational/training component and is aligned with NASA's objectives as outlined in the NRA call. Kepler is the only instrument that can provide the accuracy and temporal coverage required for the execution of this project.

Two white dwarfs in ultrashort binaries with detached, eclipsing, likely sub-stellar companions detected by K2

NASA Astrophysics Data System (ADS)

Parsons, S. G.; Hermes, J. J.; Marsh, T. R.; Gänsicke, B. T.; Tremblay, P.-E.; Littlefair, S. P.; Sahman, D. I.; Ashley, R. P.; Green, M.; Rattanasoon, S.; Dhillon, V. S.; Burleigh, M. R.; Casewell, S. L.; Buckley, D. A. H.; Braker, I. P.; Irawati, P.; Dennihy, E.; Rodríguez-Gil, P.; Winget, D. E.; Winget, K. I.; Bell, Keaton J.; Kilic, Mukremin

2017-10-01

Using data from the extended Kepler mission in K2 Campaign 10, we identify two eclipsing binaries containing white dwarfs with cool companions that have extremely short orbital periods of only 71.2 min (SDSS J1205-0242, a.k.a. EPIC 201283111) and 72.5 min (SDSS J1231+0041, a.k.a. EPIC 248368963). Despite their short periods, both systems are detached with small, low-mass companions, in one case a brown dwarf and in the other case either a brown dwarf or a low-mass star. We present follow-up photometry and spectroscopy of both binaries, as well as phase-resolved spectroscopy of the brighter system, and use these data to place preliminary estimates on the physical and binary parameters. SDSS J1205-0242 is composed of a 0.39 ± 0.02 M⊙ helium-core white dwarf that is totally eclipsed by a 0.049 ± 0.006 M⊙ (51 ± 6MJ) brown-dwarf companion, while SDSS J1231+0041 is composed of a 0.56 ± 0.07 M⊙ white dwarf that is partially eclipsed by a companion of mass ≲0.095 M⊙. In the case of SDSS J1205-0242, we look at the combined constraints from common-envelope evolution and brown-dwarf models; the system is compatible with similar constraints from other post-common-envelope binaries, given the current parameter uncertainties, but has potential for future refinement.

Tidal disruption of inclined or eccentric binaries by massive black holes

NASA Astrophysics Data System (ADS)

Brown, Harriet; Kobayashi, Shiho; Rossi, Elena M.; Sari, Re'em

2018-07-01

Binary stars that are on close orbits around massive black holes (MBHs) such as Sgr A* in the centre of the Milky Way are liable to undergo tidal disruption and eject a hypervelocity star. We study the interaction between such an MBH and circular binaries for general binary orientations and penetration depths (i.e. binaries penetrate into the tidal radius around the BH). We show that for very deep penetrators, almost all binaries are disrupted when the binary rotation axis is roughly oriented towards the BH or it is in the opposite direction. The surviving chance becomes significant when the angle between the binary rotation axis and the BH direction is between 0.15π and 0.85π. The surviving chance is as high as ˜20 per cent when the binary rotation axis is perpendicular to the BH direction. However, for shallow penetrators, the highest disruption chance is found in such a perpendicular case, especially in the prograde case. This is because the dynamics of shallow penetrators is more sensitive to the relative orientation of the binary and orbital angular momenta. We provide numerical fits to the disruption probability and energy gain at the BH encounter as a function of the penetration depth. The latter can be simply rescaled in terms of binary masses, their initial separation, and the binary-to-BH mass ratio to evaluate the ejection velocity of a binary members in various systems. We also investigate the disruption of coplanar, eccentric binaries by an MBH. It is shown that for highly eccentric binaries retrograde orbits have a significantly increased disruption probability and ejection velocities compared to the circular binaries.

Tidal Disruption of Inclined or Eccentric Binaries by Massive Black Holes

NASA Astrophysics Data System (ADS)

Brown, Harriet; Kobayashi, Shiho; Rossi, Elena M.; Sari, Re'em

2018-04-01

Binary stars that are on close orbits around massive black holes (MBH) such as Sgr A* in the centre of the Milky Way are liable to undergo tidal disruption and eject a hypervelocity star. We study the interaction between such a MBH and circular binaries for general binary orientations and penetration depths (i.e. binaries penetrate into the tidal radius around the BH). We show that for very deep penetrators, almost all binaries are disrupted when the binary rotation axis is roughly oriented toward the BH or it is in the opposite direction. The surviving chance becomes significant when the angle between the binary rotation axis and the BH direction is between 0.15π and 0.85π. The surviving chance is as high as ˜20% when the binary rotation axis is perpendicular to the BH direction. However, for shallow penetrators, the highest disruption chance is found in such a perpendicular case, especially in the prograde case. This is because the dynamics of shallow penetrators is more sensitive to the relative orientation of the binary and orbital angular momenta. We provide numerical fits to the disruption probability and energy gain at the the BH encounter as a function of the penetration depth. The latter can be simply rescaled in terms of binary masses, their initial separation and the binary-to-BH mass ratio to evaluate the ejection velocity of a binary members in various systems. We also investigate the disruption of coplanar, eccentric binaries by a MBH. It is shown that for highly eccentric binaries retrograde orbits have a significantly increased disruption probability and ejection velocities compared to the circular binaries.

CoRoT 101186644: A transiting low-mass dense M-dwarf on an eccentric 20.7-day period orbit around a late F-star. Discovered in the CoRoT lightcurves

NASA Astrophysics Data System (ADS)

Tal-Or, L.; Mazeh, T.; Alonso, R.; Bouchy, F.; Cabrera, J.; Deeg, H. J.; Deleuil, M.; Faigler, S.; Fridlund, M.; Hébrard, G.; Moutou, C.; Santerne, A.; Tingley, B.

2013-05-01

We present the study of the CoRoT transiting planet candidate 101186644, also named LRc01_E1_4780. Analysis of the CoRoT lightcurve and the HARPS spectroscopic follow-up observations of this faint (mV = 16) candidate revealed an eclipsing binary composed of a late F-type primary (Teff = 6090 ± 200 K) and a low-mass, dense late M-dwarf secondary on an eccentric (e = 0.4) orbit with a period of ~20.7 days. The M-dwarf has a mass of 0.096 ± 0.011 M⊙, and a radius of 0.104-0.006+0.026 R⊙, which possibly makes it the smallest and densest late M-dwarf reported so far. Unlike the claim that theoretical models predict radii that are 5-15% smaller than measured for low-mass stars, this one seems to have a radius that is consistent and might even be below the radius predicted by theoretical models. Based on observations made with the 1-m telescope at the Wise Observatory, Israel, the Swiss 1.2-m Leonhard Euler telescope at La Silla Observatory, Chile, the IAC-80 telescope at the Observatory del Teide, Canarias, Spain, and the 3.6-m telescope at La Silla Observatory (ESO), Chile (program 184.C-0639).

The 1984 eclipse of the symbiotic binary SY Muscae

NASA Technical Reports Server (NTRS)

Kenyon, S. J.; Michalitisianos, A. G.; Lutz, J. H.; Kafatos, M.

1985-01-01

Data from IUE spectra obtained with the 10 x 20-arcsec aperture on May 13, 1984, and optical spectrophotometry obtained with an SIT vidicon on the 1.5-m telescope at CTIO on April 29-May 1, 1984, are reported for the symbiotic binary SY Mus. The data are found to be consistent with a model of a red-giant secondary of 60 solar radii which completely eclipses the hot primary every 627 d but only partially eclipses the 75-solar-radius He(+) region surrounding the primary. The distance to SY Mus is estimated as 1.3 kpc. It is suggested that the large Balmer decrement in eclipse, with (H-alpha)/(H-beta) = 8.3 and (H-beta)/(H-gamma) = 1.5, is associated with an electron density of about 10 to the 10th/cu cm.

Periodicity and eclipse minima timing of CM Draconis.

NASA Astrophysics Data System (ADS)

Vázquez-Martín, S.; Deeg, H. J.; Dreizler, S.; von Essen, C.; Kozhevnikov, V. P.

2015-05-01

Periodic deviations from a linear ephemeris of a binary star's eclipses can indicate the presence of a third body in orbit around both. Hints for such companion around the M4.5/M4.5 binary CMDra were published by Deeg et al. (2008). The assignment of a planet in the CMDra system can however only be accepted if the earlier observed periodicity trends can be verified through further observations over several years. For eclipsing binary stars of low mass, the method of eclipse minimum timing allows one to set mass limits for the detection of a third body. Deeg et al. (2008) concluded that the two possibilities for the source of CMDra's timing variations that remain valid are a planet of a few Jupiter masses on a two decade-long orbit, or an object on a century-to-millenium long orbit with masses 1.5M_J < M_{p} < 0.1M_{⊙}. However, they concluded that it is necessary to do continued observations of the timing of CMDra's eclipses to be decisive regarding the continued viability of the sinusoidal-fit-model, and hence, about the validity of a Jovian-type planet in a circumbinary orbiting around the system. Here we update the analysis of Deeg et al. (2008), including further data presented in Morales et al. (2009r) and new observations taken at Ural Observatory (2008-2013). Eclipse minimum times were obtained using the Kwee-van-Woerden method.

Record-Breaking Eclipsing Binary

NASA Astrophysics Data System (ADS)

Kohler, Susanna

2016-05-01

A new record holder exists for the longest-period eclipsing binary star system: TYC-2505-672-1. This intriguing system contains a primary star that is eclipsed by its companion once every 69 years with each eclipse lasting several years!120 Years of ObservationsIn a recent study, a team of scientists led by Joseph Rodriguez (Vanderbilt University) characterizes the components of TYC-2505-672-1. This binary star system consists of an M-type red giant star that undergoes a ~3.45-year-long, near-total eclipse with a period of ~69.1 years. This period is more than double that of the previous longest-period eclipsing binary!Rodriguez and collaborators combined photometric observations of TYC-2505-672-1 by the Kilodegree Extremely Little Telescope (KELT) with a variety of archival data, including observations by the American Association of Variable Star Observers (AAVSO) network and historical data from the Digital Access to a Sky Century @ Harvard (DASCH) program.In the 120 years spanned by these observations, two eclipses are detected: one in 1942-1945 and one in 2011-2015. The authors use the observations to analyze the components of the system and attempt to better understand what causes its unusual light curve.Characterizing an Unusual SystemObservations of TYC-2505-672-1 plotted from 1890 to 2015 reveal two eclipses. (The blue KELT observations during the eclipse show upper limits only.) [Rodriguez et al. 2016]By modeling the systems emission, Rodriguez and collaborators establish that TYC-2505-672-1 consists of a 3600-K primary star thats the M giant orbited by a small, hot, dim companion thats a toasty 8000 K. But if the companion is small, why does the eclipse last several years?The authors argue that the best model of TYC-2505-672-1 is one in which the small companion star is surrounded by a large, opaque circumstellar disk. Rodriguez and collaborators suggest that the companion could be a former red giant whose atmosphere was stripped from it, leaving behind the small, hot core shrouded by a large, cool disk of stripped gas. The large size of the disk causes the eclipse of the primary to last for years, as viewed from Earth.The authors estimate the properties such a disk would need to produce the observed light curve. They find that if the companion were surrounded by a disk several AU in diameter, it could orbit at a distance of ~20-30 AU from the primary and reproduce the emission we see.The next eclipse of TYC-2505-672-1 will begin in April 2080. We neednt wait until then to gather more information about this system, however! Radial velocity measurements will help establish the masses of the two components, and high-cadence UV observations could reveal more about the evolutionary state of the system. Studying this extreme binary provides an excellent opportunity to learn more about the environments in late-life star systems.CitationJoseph E. Rodriguez et al 2016 AJ 151 123. doi:10.3847/0004-6256/151/5/123

Absolute Parameters for the F-type Eclipsing Binary BW Aquarii

NASA Astrophysics Data System (ADS)

Maxted, P. F. L.

2018-05-01

BW Aqr is a bright eclipsing binary star containing a pair of F7V stars. The absolute parameters of this binary (masses, radii, etc.) are known to good precision so they are often used to test stellar models, particularly in studies of convective overshooting. ... Maxted & Hutcheon (2018) analysed the Kepler K2 data for BW Aqr and noted that it shows variability between the eclipses that may be caused by tidally induced pulsations. ... Table 1 shows the absolute parameters for BW Aqr derived from an improved analysis of the Kepler K2 light curve plus the RV measurements from both Imbert (1979) and Lester & Gies (2018). ... The values in Table 1 with their robust error estimates from the standard deviation of the mean are consistent with the values and errors from Maxted & Hutcheon (2018) based on the PPD calculated using emcee for a fit to the entire K2 light curve.

The Search for Pre-Main Sequence Eclipsing Binary Stars in the Lagoon Nebula

NASA Astrophysics Data System (ADS)

Henderson, Calen B.; Stassun, K. G.

2009-01-01

We report time-series CCD I-band photometry for the pre-main-sequence cluster NGC 6530, located within the Lagoon Nebula. The data were obtained with the 4Kx4K imager on the SMARTS 1.0m telescope at CTIO on 36 nights over the summers of 2005 and 2006. In total we have light curves for 50,000 stars in an area 1 deg2, with a sampling cadence of 1 hour. The stars in our sample have masses in the range 0.25-4.0 Msun, assuming a distance of 1.25 kpc to the cluster. Our goals are to look for stars with rotation periods and to identify eclipsing binary candidates. Here we present light curves of photometrically variable stars and potential eclipsing binary star systems. This work has been supported by the National Science Foundation under Career grant AST-0349075.

The observed distribution of spectroscopic binaries from the Anglo-Australian Planet Search

NASA Astrophysics Data System (ADS)

Jenkins, J. S.; Díaz, M.; Jones, H. R. A.; Butler, R. P.; Tinney, C. G.; O'Toole, S. J.; Carter, B. D.; Wittenmyer, R. A.; Pinfield, D. J.

2015-10-01

We report the detection of sixteen binary systems from the Anglo-Australian Planet Search. Solutions to the radial velocity data indicate that the stars have companions orbiting with a wide range of masses, eccentricities and periods. Three of the systems potentially contain brown-dwarf companions while another two have eccentricities that place them in the extreme upper tail of the eccentricity distribution for binaries with periods less than 1000 d. For periods up to 12 years, the distribution of our stellar companion masses is fairly flat, mirroring that seen in other radial velocity surveys, and contrasts sharply with the current distribution of candidate planetary masses, which rises strongly below 10 MJ. When looking at a larger sample of binaries that have FGK star primaries as a function of the primary star metallicity, we find that the distribution maintains a binary fraction of ˜43 ± 4 per cent between -1.0 and +0.6 dex in metallicity. This is in stark contrast to the giant exoplanet distribution. This result is in good agreement with binary formation models that invoke fragmentation of a collapsing giant molecular cloud, suggesting that this is the dominant formation mechanism for close binaries and not fragmentation of the primary star's remnant protoplanetary disc.

Applications Of Binary Image Analysis Techniques

NASA Astrophysics Data System (ADS)

Tropf, H.; Enderle, E.; Kammerer, H. P.

1983-10-01

After discussing the conditions where binary image analysis techniques can be used, three new applications of the fast binary image analysis system S.A.M. (Sensorsystem for Automation and Measurement) are reported: (1) The human view direction is measured at TV frame rate while the subject's head is free movable. (2) Industrial parts hanging on a moving conveyor are classified prior to spray painting by robot. (3) In automotive wheel assembly, the eccentricity of the wheel is minimized by turning the tyre relative to the rim in order to balance the eccentricity of the components.

Dynamics of quadruple systems composed of two binaries: stars, white dwarfs, and implications for Ia supernovae

NASA Astrophysics Data System (ADS)

Fang, Xiao; Thompson, Todd A.; Hirata, Christopher M.

2018-05-01

We investigate the long-term secular dynamics and Lidov-Kozai (LK) eccentricity oscillations of quadruple systems composed of two binaries at quadrupole and octupole orders in the perturbing Hamiltonian. We show that the fraction of systems reaching high eccentricities is enhanced relative to triple systems, over a broader range of parameter space. We show that this fraction grows with time, unlike triple systems evolved at quadrupole order. This is fundamentally because with their additional degrees of freedom, quadruple systems do not have a maximal set of commuting constants of the motion, even in secular theory at quadrupole order. We discuss these results in the context of star-star and white dwarf-white dwarf (WD) binaries, with emphasis on WD-WD mergers and collisions relevant to the Type Ia supernova problem. For star-star systems, we find that more than 30 per cent of systems reach high eccentricity within a Hubble time, potentially forming triple systems via stellar mergers or close binaries. For WD-WD systems, taking into account general relativistic and tidal precession and dissipation, we show that the merger rate is enhanced in quadruple systems relative to triple systems by a factor of 3.5-10, and that the long-term evolution of quadruple systems leads to a delay-time distribution ˜1/t for mergers and collisions. In gravitational wave-driven mergers of compact objects, we classify the mergers by their evolutionary patterns in phase space and identify a regime in about 8 per cent of orbital shrinking mergers, where eccentricity oscillations occur on the general relativistic precession time-scale, rather than the much longer LK time-scale. Finally, we generalize previous treatments of oscillations in the inner binary eccentricity (evection) to eccentric mutual orbits. We assess the merger rate in quadruple and triple systems and the implications for their viability as progenitors of stellar mergers and Type Ia supernovae.

New Precision Orbits of Bright Double-lined Spectroscopic Binaries. X. HD 96511, HR 7578, and KZ Andromedae

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fekel, Francis C.; Henry, Gregory W.; Tomkin, Jocelyn, E-mail: fekel@evans.tsuniv.edu, E-mail: gregory.w.henry@gmail.com

2017-09-01

From an extensive number of newly acquired radial velocities we determine the orbital elements for three late-type dwarf systems, HD 96511, HR 7578, and KZ And. The orbital periods are 18.89737 ± 0.00002, 46.81610 ± 0.00006, and 3.0329113 ± 0.0000005 days, respectively, and all three systems are eccentric, although KZ And is just barely so. We have detected lines of the secondary of HD 96511 for the first time. The orbital dimensions ( a {sub 1} sin i and a {sub 2} sin i ) and minimum masses ( m {sub 1} sin{sup 3} i and m {sub 2} sin{sup 3} i ) of the binary components all have accuracies ofmore » 0.2% or better. Extensive photometry of the chromospherically active binary HR 7578 confirms a rather long rotation period of 16.446 ± 0.002 days and that the K3 V components do not eclipse. We have estimated the basic properties of the stars in the three systems and compared those results with evolutionary tracks. The results for KZ And that we computed with the revised Hipparcos parallax of van Leeuwen produce inconsistencies. That parallax appears to be too large, and so, instead, we used the original Hipparcos parallax of the common proper motion primary, which improves the results, although some problems remain.« less

Contact Binaries on Their Way Towards Merging

NASA Astrophysics Data System (ADS)

Gazeas, K.

2015-07-01

Contact binaries are the most frequently observed type of eclipsing star system. They are small, cool, low-mass binaries belonging to a relatively old stellar population. They follow certain empirical relationships that closely connect a number of physical parameters with each other, largely because of constraints coming from the Roche geometry. As a result, contact binaries provide an excellent test of stellar evolution, specifically for stellar merger scenarios. Observing campaigns by many authors have led to the cataloging of thousands of contact binaries and enabled statistical studies of many of their properties. A large number of contact binaries have been found to exhibit extraordinary behavior, requiring follow-up observations to study their peculiarities in detail. For example, a doubly-eclipsing quadruple system consisting of a contact binary and a detached binary is a highly constrained system offering an excellent laboratory to test evolutionary theories for binaries. A new observing project was initiated at the University of Athens in 2012 in order to investigate the possible lower limit for the orbital period of binary systems before coalescence, prior to merging.

The first comprehensive catalog of γ Dor pulsators and their characteristics

NASA Astrophysics Data System (ADS)

Ibanoglu, C.; Çakırlı, Ö.; Sipahi, E.

2018-07-01

We present the first comprehensive catalog of the γ Doradus type pulsating stars. This catalog covers observational properties of all γ Dor variables obtained until January 2017. The photometric and physical properties of 109 well - known γ Dor pulsators, 18 hybrid stars, 13 anomalous γ Dor stars, and 22 γ Dor stars in eclipsing plus 1 non-eclipsing SB2 binary systems are presented as separate tables. In addition, 291 candidate γ Dor variables discovered by CoRot, 307 candidate γ Dor, 205 hybrid and 11 candidate γ Dor in binaries discovered by Kepler were also presented. Distribution of the genuine single γ Dor pulsators in the Ppuls-Teff, Amplitude-Teff, Amplitude-Ppuls and L-Teff diagrams are presented and discussed. We find following correlations for the γ Dor pulsators in the eclipsing binaries: Ppuls ∝ Porb0.27, Ppuls ∝ Q0.45, and Ppuls ∝ r-0.44, where (Q) is the pulsation constant and r is the fractional radius of the pulsating component in the binary system. The correlation coefficients are not high enough due to limited sample and scattering in the data.

Observations and Light Curve Solutions of the Eclipsing Binaries KR Lyn, CSS J110212+244412, NSVS 4917488 and NSVS 7336024

NASA Astrophysics Data System (ADS)

Kjurkchieva, D.; Popov, V. A.; Eneva, J.; Petrov, N.

2018-05-01

We present photometric observations in Sloan filters g', i' of the short-period eclipsing stars KR Lyn, CSS J110212+244412, NSVS 4917488 and NSVS 7336024. The light curve solutions revealed that all targets are overcontact binaries whose components are G and K stars. Their temperature differences do not exceed 300 K but they differ considerably in size and mass. NSVS 4917488 and NSVS 7336024 reveal total eclipses and their parameters can be considered as well-determined. We found that KR Lyn, NSVS 4917488 and NSVS 7336024 are of W-subtype while CSS J110212+244412 is A-subtype W UMa-type star.

Einstein@Home DISCOVERY OF A PALFA MILLISECOND PULSAR IN AN ECCENTRIC BINARY ORBIT

DOE Office of Scientific and Technical Information (OSTI.GOV)

Knispel, B.; Allen, B.; Lyne, A. G.

2015-06-10

We report the discovery of the millisecond pulsar (MSP) PSR J1950+2414 (P = 4.3 ms) in a binary system with an eccentric (e = 0.08) 22 day orbit in Pulsar Arecibo L-band Feed Array survey observations with the Arecibo telescope. Its companion star has a median mass of 0.3 M{sub ⊙} and is most likely a white dwarf (WD). Fully recycled MSPs like this one are thought to be old neutron stars spun-up by mass transfer from a companion star. This process should circularize the orbit, as is observed for the vast majority of binary MSPs, which predominantly have orbitalmore » eccentricities e < 0.001. However, four recently discovered binary MSPs have orbits with 0. 027 < e < 0.44; PSR J1950+2414 is the fifth such system to be discovered. The upper limits for its intrinsic spin period derivative and inferred surface magnetic field strength are comparable to those of the general MSP population. The large eccentricities are incompatible with the predictions of the standard recycling scenario: something unusual happened during their evolution. Proposed scenarios are (a) initial evolution of the pulsar in a triple system which became dynamically unstable, (b) origin in an exchange encounter in an environment with high stellar density, (c) rotationally delayed accretion-induced collapse of a super-Chandrasekhar WD, and (d) dynamical interaction of the binary with a circumbinary disk. We compare the properties of all five known eccentric MSPs with the predictions of these formation channels. Future measurements of the masses and proper motion might allow us to firmly exclude some of the proposed formation scenarios.« less

The Exciting World of Binary Stars: Not Just Eclipses Anymore (Abstract)

NASA Astrophysics Data System (ADS)

Pablo, B.

2018-06-01

(Abstract only) Binary stars have always been essential to astronomy. Their periodic eclipses are the most common and efficient method for determining precise masses and radii of stars. Binaries are known for their predictability and have been observed for hundreds if not thousands of years. As such, they are often ignored by observers as uninteresting, however, nothing could be farther from the truth. In the last ten years alone the importance of binary stars, as well of our knowledge of them, has changed significantly. In this talk, I will introduce you to this new frontier of heartbeats, mergers, and evolution, while hopefully motivating a change in the collective thinking of how this unique class of objects is viewed. Most importantly,

1998 UBV Light Curves of Eclipsing Binary AI Draconis and Absolute Parameters

NASA Astrophysics Data System (ADS)

Jassur, D. M. Z.; Khaledian, M. S.; Kermani, M. H.

New UBV photometry of Algol-Type eclipsing binary star AI Dra and the absolute physical parameters of this system have been presented. The light curve analysis carried out by the method of differential corrections indicates that both components are inside their Roche-Lobes. From combining the photometric solution with spectroscopic data obtained from velocity curve analysis, it has been found that the system consist of a main sequence primary and an evolved (subgiant) secondary.

A Photometric Study of the Eclipsing Binary NSV 1000

NASA Astrophysics Data System (ADS)

Richards, T. J.; Bembrick, C. S.

2018-06-01

Abstract NSV 1000 is an unstudied eclipsing binary in Hydrus. Our photometric research in the period 2014-2016 shows it is a W UMa system with a period of 0.336 579 6(3) d, consistent with the catalogued period. Model fitting to our B, V, and Ic light curves shows the two stars are barely in contact. The parameters derived from the fit satisfy the broadly defined characteristics of a W-type W UMa system.

A Bright Short Period M-M Eclipsing Binary from the KELT Survey: Magnetic Activity and the Mass-Radius Relationship for M Dwarfs

NASA Astrophysics Data System (ADS)

Lubin, Jack B.; Rodriguez, Joseph E.; Zhou, George; Conroy, Kyle E.; Stassun, Keivan G.; Collins, Karen; Stevens, Daniel J.; Labadie-Bartz, Jonathan; Stockdale, Christopher; Myers, Gordon; Colón, Knicole D.; Bento, Joao; Kehusmaa, Petri; Petrucci, Romina; Jofré, Emiliano; Quinn, Samuel N.; Lund, Michael B.; Kuhn, Rudolf B.; Siverd, Robert J.; Beatty, Thomas G.; Harlingten, Caisey; Pepper, Joshua; Gaudi, B. Scott; James, David; Jensen, Eric L. N.; Reichart, Daniel; Kedziora-Chudczer, Lucyna; Bailey, Jeremy; Melville, Graeme

2017-08-01

We report the discovery of KELT J041621-620046, a moderately bright (J ˜ 10.2) M-dwarf eclipsing binary system at a distance of 39 ± 3 pc. KELT J041621-620046 was first identified as an eclipsing binary using observations from the Kilodegree Extremely Little Telescope (KELT) survey. The system has a short orbital period of ˜1.11 days and consists of components with {M}1={0.447}+0.052-0.047 {M}⊙ and {M}2={0.399}+0.046-0.042 {M}⊙ in nearly circular orbits. The radii of the two stars are {R}1={0.540}+0.034-0.032 {R}⊙ and {\\text{}}{R}2=0.453+/- 0.017 {R}⊙ . Full system and orbital properties were determined (to ˜10% error) by conducting an EBOP (Eclipsing Binary Orbit Program) global modeling of the high precision photometric and spectroscopic observations obtained by the KELT Follow-up Network. Each star is larger by 17%-28% and cooler by 4%-10% than predicted by standard (non-magnetic) stellar models. Strong Hα emission indicates chromospheric activity in both stars. The observed radii and temperature discrepancies for both components are more consistent with those predicted by empirical relations that account for convective suppression due to magnetic activity.

A connection between long-term luminosity variations and orbital period changes in chromospherically active binaries

NASA Technical Reports Server (NTRS)

Hall, Douglas S.

1991-01-01

The eclipsing binary CG Cyg provides observational confirmation of three predictions made by Applegate's (1991) improvement on the theory that magnetic cycles cause the quasi-periodic orbital period changes in binaries containing a convective star. The mean brightness outside eclipse and the period vary with the same cycle length of about 50 yr. The light curve and O - C curve are in phase, with maximum light and period increase occurring in early 1980. The chromospherically active star becomes bluer in phase with the brightening. Because a period increase occurs at maximum brightness, the sense of the star's differential rotation is specified: outside rotating faster.

A SUBSTELLAR COMPANION TO THE WHITE DWARF-RED DWARF ECLIPSING BINARY NN Ser

DOE Office of Scientific and Technical Information (OSTI.GOV)

Qian, S.-B.; Dai, Z.-B.; Liao, W.-P.

2009-11-20

NN Ser is a short-period (P = 3.12 hr) close binary containing a very hot white dwarf primary with a mass of 0.535 M{sub sun} and a fully convective secondary with a mass of 0.111 M{sub sun}. The changes in the orbital period of the eclipsing binary were analyzed based on our five newly determined eclipse times together with those compiled from the literature. A small-amplitude (0fd00031) cyclic period variation with a period of 7.56 years was discovered to be superimposed on a possible long-term decrease. The periodic change was plausibly explained as the light-travel time effect via the presencemore » of a tertiary companion. The mass of the tertiary companion is determined to be M{sub 3}sin i' = 0.0107(+-0.0017) M{sub sun} when a total mass of 0.646 M{sub sun} for NN Ser is adopted. For orbital inclinations i' >= 49.{sup 0}56, the mass of the tertiary component was calculated to be M {sub 3} <= 0.014 M{sub sun}; thus it would be an extrasolar planet. The third body is orbiting the white dwarf-red dwarf eclipsing binary at a distance shorter than 3.29 AU. Since the observed decrease rate of the orbital period is about two orders larger than that caused by gravitational radiation, it can be plausibly interpreted by magnetic braking of the fully convective component, which is driving this binary to evolve into a normal cataclysmic variable.« less

The Light-time Effect in the Eclipsing Binaries with Early-type Components U CrB and RW Tau

NASA Astrophysics Data System (ADS)

Khaliullina, A. I.

2018-04-01

A detailed study of the orbital-period variations of the Algol-type eclipsing binaries with earlyspectral- type primary components U CrB and RW Tau has been performed. The period variations in both systems can be described as a superposition of secular and cyclic variations of the period. A secular period increase at a rate of 2.58d × 10-7/year is observed for U CrB, which can be explained if there is a uniform flow of matter from the lower-mass to the higher-mass component, with the total angular momentum conserved. RW Tau features a secular period decrease at a rate of -8.6d × 10-7/year; this could be due to a loss of angular momentum by the binary due to magnetic braking. The cyclic orbital-period variations of U CrB and RWTau can be explained by the motion of the eclipsing binary systems along their long-period orbits. In U CrB, this implies that the eclipsing binary moves with a period of 91.3 years around a third body with mass M 3 > 1.13 M ⊙; in RW Tau, the period of the motion around the third body is 66.6 years, and the mass of the third body is M 3 > 1.24 M ⊙. It also cannot be ruled out that the variations are due to the magnetic cycles of the late-type secondaries. The residual period variations could be a superposition of variations due to non-stationary ejection of matter and effects due to magnetic cycles.

The puzzling orbital period evolution of the LMXB AX J1745.6-2901

NASA Astrophysics Data System (ADS)

Ponti, G.; De, K.; Munoz-Darias, T.; Stella, L.; Nandra, K.

2017-10-01

The discovery of gravitational waves through mergers of binary black holes raises the question of how such compact systems form, renewing issues related to the orbital evolution of binary systems. Eclipsing X-ray binaries are excellent tools to constrain the orbital period evolution and how the system loses angular momentum. I will present an X-ray eclipse timing analysis (spanning an interval of more than 20 yr) of one of such objects, AX J1745.6-2901. Its orbital period is decreasing at a rate Pdotorb=-4.03+-0.32 e-11 s s-1, at least one order of magnitude larger than expected from conservative mass transfer and angular momentum losses due to gravitational waves and magnetic braking, and it might result from either non-conservative mass transfer or magnetic activity changing the quadrupole moment of the companion star. I will also show that imprinted on the long-term evolution of the orbit, there are highly significant eclipse leads delays of 10-30 s, characterized by a clear state dependence in which, on average, eclipses occur earlier during the hard state. Finally, I will discuss whether accretion disc winds might have an impact onto the orbital evolution.

Hot subdwarfs in (eclipsing) binaries with brown dwarf or low-mass main-sequence companions

NASA Astrophysics Data System (ADS)

Schaffenroth, Veronika; Geier, Stephan; Heber, Uli

2014-09-01

The formation of hot subdwarf stars (sdBs), which are core helium-burning stars located on the extended horizontal branch, is not yet understood. Many of the known hot subdwarf stars reside in close binary systems with short orbital periods of between a few hours and a few days, with either M-star or white-dwarf companions. Common-envelope ejection is the most probable formation channel. Among these, eclipsing systems are of special importance because it is possible to constrain the parameters of both components tightly by combining spectroscopic and light-curve analyses. They are called HW Virginis systems. Soker (1998) proposed that planetary or brown-dwarf companions could cause the mass loss necessary to form an sdB. Substellar objects with masses greater than >10 M_J were predicted to survive the common-envelope phase and end up in a close orbit around the stellar remnant, while planets with lower masses would entirely evaporate. This raises the question if planets can affect stellar evolution. Here we report on newly discovered eclipsing or not eclipsing hot subdwarf binaries with brown-dwarf or low-mass main-sequence companions and their spectral and photometric analysis to determine the fundamental parameters of both components.

Mapping the accretion disc of the short period eclipsing binary SDSS J0926+3624

NASA Astrophysics Data System (ADS)

Schlindwein, Wagner; Baptista, Raymundo

2018-05-01

We report the analysis of time-series of optical photometry of SDSS J0926+3624 collected with the Liverpool Robotic Telescope between 2012 February and March while the object was in quiescence. We combined our median eclipse timing with those in the literature to revise the ephemeris and confirm that the binary period is increasing at a rate \\dot{P}=(3.2 ± 0.4)× 10^{-13} s/s. The light curves show no evidence of either the orbital hump produced by a bright spot at disc rim or of superhumps; the average out-of-eclipse brightness level is consistently lower than previously reported. The eclipse map from the average light curve shows a hot white dwarf surrounded by a faint, cool accretion disc plus enhanced emission along the gas stream trajectory beyond the impact point at the outer disc rim, suggesting the occurrence of gas stream overflow/penetration at that epoch. We estimate a disc mass input rate of \\dot{M}=(9 ± 1)× 10^{-12} M_⊙ yr^{-1}, more than an order of magnitude lower than that expected from binary evolution with conservative mass transfer.

Digitizing Villanova University's Eclipsing Binary Card Catalogue

NASA Astrophysics Data System (ADS)

Guzman, Giannina; Dalton, Briana; Conroy, Kyle; Prsa, Andrej

2018-01-01

Villanova University’s Department of Astrophysics and Planetary Science has years of hand-written archival data on Eclipsing Binaries at its disposal. This card catalog began at Princeton in the 1930’s with notable contributions from scientists such as Henry Norris Russel. During World War II, the archive was moved to the University of Pennsylvania, which was one of the world centers for Eclipsing Binary research, consequently, the contributions to the catalog during this time were immense. It was then moved to University of Florida at Gainesville before being accepted by Villanova in the 1990’s. The catalog has been kept in storage since then. The objective of this project is to digitize this archive and create a fully functional online catalog that contains the information available on the cards, along with the scan of the actual cards. Our group has built a database using a python-powered infrastructure to contain the collected data. The team also built a prototype web-based searchable interface as a front-end to the catalog. Following the data-entry process, information like the Right Ascension and Declination will be run against SIMBAD and any differences between values will be noted as part of the catalog. Information published online from the card catalog and even discrepancies in information for a star, could be a catalyst for new studies on these Eclipsing Binaries. Once completed, the database-driven interface will be made available to astronomers worldwide. The group will also acquire, from the database, a list of referenced articles that have yet to be found online in order to further pursue their digitization. This list will be comprised of references in the cards that were neither found on ADS nor online during the data-entry process. Pursuing the integration of these references to online queries such as ADS will be an ongoing process that will contribute and further facilitate studies on Eclipsing Binaries.

Detection of the Secondary Eclipse of Exoplanet HAT P-11b

NASA Technical Reports Server (NTRS)

Barry, R. K.; Deming, L. D.; Bakos, G.; Harrington, J.; Madhusudhan, N.; Noyes, R.; Seager, S.

2010-01-01

We have successfully conducted secondary eclipse observations of exoplanet HAT-P-11b using the Spitzer Space Telescope. HAT-P-11b was, until very recently, the smallest transiting extrasolar planet yet found and one of only two known exo-Neptunes. We observed the system at 3.6 microns for a period of 22 hours centered on the anticipated secondary eclipse time, to detect the eclipse and determine its phase. Having detected the secondary eclipse, we are at present making a more focused series of observations in both the 3.6 and 4.5 micron bands to fully characterize it. HAT-P-11b has a period of 4.8878 days, radius of 0.422 RJ, mass of 0.081 MJ and semi-major axis 0.053 AU. Measurements of the secondary eclipse will serve to clarify two key issues; 1) the planetary brightness temperature and the nature of its atmosphere, and 2) the eccentricity of its orbit, with implications for its dynamical evolution. A precise determination of the orbit phase for the secondary eclipse will also be of great utility for Kepler observations of this system at visible wavelengths.

Observations and light curve solutions of a selection of middle-contact W UMa binaries

NASA Astrophysics Data System (ADS)

Kjurkchieva, Diana Petrova; Popov, Velimir Angelov; Lyubenova Vasileva, Doroteya; Petrov, Nikola Ivanov

2018-04-01

Photometric observations in Sloan g‧ and i‧ bands of W UMa binaries NSVS 4340949, T-Dra0–00959, GSC 03950–00707, NSVS 4665041, NSVS 4803568, MM Peg, MM Com and NSVS 4751449 are presented. The light curve solutions revealed that the components of each target are of G and K spectral types. The binaries of the sample have middle-contact configurations whose fillout factors are within the range 0.2–0.4. The only exception is NSVS 4751449 which is in deeper contact (fillout factor of 0.55). It precisely obeys the relation between mass ratio and fillout factor for deep, low mass ratio overcontact binaries. One of the eclipses of almost all targets (except MM Peg) is an occultation and their photometric mass ratios and solutions could be accepted with confidence. We found that the target components have almost equal temperatures but differ considerably in size and mass. The components of the partially-eclipsed MM Peg have close parameters. Our solutions reveal that NSVS 4340949, T-Dra0–00959, NSVS 4803568 and MM Com are of W subtype while GSC 03950–00707, NSVS 4665041, MM Peg and NSVS 4751449 are of A subtype. This subclassification is well-determined for all totally-eclipsed binaries. The targets confirm the trends in which W-subtype systems have smaller periods and lower temperatures than A subtype binaries.

WW Geminorum: An Early B-type Eclipsing Binary Evolving into the Contact Phase

NASA Astrophysics Data System (ADS)

Yang, Y.-G.; Yang, Y.; Dai, H.-F.; Yin, X.-G.

2014-11-01

WW Gem is a B-type eclipsing binary with a period of 1.2378 days. The CCD photometry of this binary was performed in 2013 December using the 85 cm telescope at the Xinglong Stations of the National Astronomical Observatories of China. Using the updated W-D program, the photometric model was deduced from the VRI light curves. The results imply that WW Gem is a near-contact eclipsing binary whose primary component almost fills its Roche lobe. The photometric mass ratio is q ph = 0.48(± 0.05). All collected times of minimum light, including two new ones, were used for the period studies. The orbital period changes of WW Gem could be described by an upward parabola, possibly overlaid by a light-time orbit with a period of P mod = 7.41(± 0.04) yr and a semi-amplitude of A = 0.0079 days(± 0.0005 days), respectively. This kind of cyclic oscillation may be attributed to the light-travel time effect via the third body. The long-term period increases at a rate of dP/dt = +3.47(±0.04) × 10-8 day yr-1, which may be explained by the conserved mass transfer from the less massive component to the more massive one. With mass transfer, the massive binary WW Gem may be evolving into a contact binary.

The Palomar Transient Factory Orion Project: Eclipsing Binaries and Young Stellar Objects

NASA Astrophysics Data System (ADS)

van Eyken, Julian C.; Ciardi, David R.; Rebull, Luisa M.; Stauffer, John R.; Akeson, Rachel L.; Beichman, Charles A.; Boden, Andrew F.; von Braun, Kaspar; Gelino, Dawn M.; Hoard, D. W.; Howell, Steve B.; Kane, Stephen R.; Plavchan, Peter; Ramírez, Solange V.; Bloom, Joshua S.; Cenko, S. Bradley; Kasliwal, Mansi M.; Kulkarni, Shrinivas R.; Law, Nicholas M.; Nugent, Peter E.; Ofek, Eran O.; Poznanski, Dovi; Quimby, Robert M.; Grillmair, Carl J.; Laher, Russ; Levitan, David; Mattingly, Sean; Surace, Jason A.

2011-08-01

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 (3fdg5 × 2fdg3) 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 one previously reported as a candidate weak-line T-Tauri star (SDSS J052700.12+010136.8).

WARM SPITZER PHOTOMETRY OF THREE HOT JUPITERS: HAT-P-3b, HAT-P-4b AND HAT-P-12b

DOE Office of Scientific and Technical Information (OSTI.GOV)

Todorov, Kamen O.; Deming, Drake; Knutson, Heather A.

2013-06-20

We present Warm Spitzer/IRAC secondary eclipse time series photometry of three short-period transiting exoplanets, HAT-P-3b, HAT-P-4b and HAT-P-12b, in both the available 3.6 and 4.5 {mu}m bands. HAT-P-3b and HAT-P-4b are Jupiter-mass objects orbiting an early K and an early G dwarf star, respectively. For HAT-P-3b we find eclipse depths of 0.112%+0.015%-0.030% (3.6 micron) and 0.094%+0.016%-0.009% (4.5 {mu}m). The HAT-P-4b values are 0.142%+0.014%-0.016% (3.6 micron) and 0.122%+0.012%-0.014% 4.5 {mu}m). The two planets' photometry is consistent with inefficient heat redistribution from their day to night sides (and low albedos), but it is inconclusive about possible temperature inversions in their atmospheres. HAT-P-12bmore » is a Saturn-mass planet and is one of the coolest planets ever observed during secondary eclipse, along with the hot Neptune GJ 436b and the hot Saturn WASP-29b. We are able to place 3{sigma} upper limits on the secondary eclipse depth of HAT-P-12b in both wavelengths: <0.042% (3.6 {mu}m) and <0.085% (4.5 {mu}m). We discuss these results in the context of the Spitzer secondary eclipse measurements of GJ 436b and WASP-29b. It is possible that we do not detect the eclipses of HAT-P-12b due to high eccentricity, but find that weak planetary emission in these wavelengths is a more likely explanation. We place 3{sigma} upper limits on the |e cos {omega}| quantity (where e is eccentricity and {omega} is the argument of periapsis) for HAT-P-3b (<0.0081) and HAT-P-4b (<0.0042), based on the secondary eclipse timings.« less

Orbital period variation study of the low-mass Algol eclipsing binary AI Draconis

NASA Astrophysics Data System (ADS)

Hanna, Magdy A.

2013-06-01

Orbital period changes for the Algol-type eclipsing binary AI Dra were studied based on the analysis of its observed times of light minimum. The period variation showed cyclic changes in the interval from JD. ≈ 24 36000 to JD. ≈ 24 47500 and a secular period increase rate (dP/dt = 2.44 × 10-7 d/year) starting from JD. ≈ 24 48500 up to 24 55262, in a time scale equals to 5 × 106 year.

Variable Star and Exoplanet Section of the Czech Astronomical Society

NASA Astrophysics Data System (ADS)

Brát, L.; Zejda, M.

2010-12-01

We present activities of Czech variable star observers organized in the Variable Star and Exoplanet Section of the Czech Astronomical Society. We work in four observing projects: B.R.N.O. - eclipsing binaries, MEDUZA - intrinsic variable stars, TRESCA - transiting exoplanets and candidates, HERO - objects of high energy astrophysics. Detailed information together with O-C gate (database of eclipsing binaries minima timings) and OEJV (Open European Journal on Variable stars) are available on our internet portal http://var.astro.cz.

YSOVAR: Six Pre-main-sequence Eclipsing Binaries in the Orion Nebula Cluster

DTIC Science & Technology

2012-06-25

reserved. Printed in the U.S.A. YSOVAR: SIX PRE-MAIN-SEQUENCE ECLIPSING BINARIES IN THE ORION NEBULA CLUSTER M. Morales-Calderón1,2, J. R. Stauffer1, K. G...multi-color light curves for∼2400 candidate Orion Nebula Cluster (ONC) members from our Warm Spitzer Exploration Science Program YSOVAR, we have...readable tables 1. INTRODUCTION The Orion Nebula Cluster (ONC) contains several thousand members, and since it is nearby, it provides an excellent em

First Spectroscopic Solutions of Two Southern Eclipsing Binaries: HO Tel and QY Tel

NASA Astrophysics Data System (ADS)

Sürgit, D.; Erdem, A.; Engelbrecht, C. A.; van Heerden, P.; Manick, R.

2015-07-01

We present preliminary results from the analysis of spectroscopic observations of two southern eclipsing binary stars, HO Tel and QY Tel. The grating spectra of these two systems were obtained at the Sutherland Station of the South African Astronomical Observatory in 2013. Radial velocities of the components were determined by the Fourier disentangling technique. Keplerian radial velocity models of HO Tel and QY Tel give their mass ratio as 0.921±0.005 and 1.089±0.007, respectively.

VizieR Online Data Catalog: Light curves for the eclipsing binary V1094 Tau (Maxted+, 2015)

NASA Astrophysics Data System (ADS)

Maxted, P. F. L.; Hutcheon, R. J.; Torres, G.; Lacy, C. H. S.; Southworth, J.; Smalley, B.; Pavlovski, K.; Marschall, L. A.; Clausen, J. V.

2015-04-01

Photometric light curves of the detached eclipsing binary V1094 Tau in the Stroemgren u-,v-,b- and y-bands, and in the Johnson V-band. The curves in the Stroemgren bands were obtained with the Stroemgren Automatic Telescope (SAT) at ESO, La Silla. The curves in the V-band were obtained with the NFO telescope in New Mexico and with the URSA telescope at the University of Arkansas. (6 data files).

The KOI 425 Multi-star System

NASA Astrophysics Data System (ADS)

Hughes, Anna; Boley, Aaron C.

2017-10-01

Kepler Object of Interest 425 (KOI 425) is an eclipsing binary with periodic features in addition to the known primary and secondary transits. This KOI has been observed by Saterne et al. 2012 with SOPHIE, who found its phase variance to be indicative of a diluted eclipsing binary, likely produced by a multi-star system. We analyze the complete set of Kepler archival data for this system along with the published SOPHIE results to assess the multiplicity and the dynamics of the system.

GK Dra: a delta Scuti Star in a New Eclipsing System Discovered by Hipparcos

NASA Astrophysics Data System (ADS)

Dallaporta, Sergio; Tomov, Toma; Zwitter, Tomaz; Munari, Ulisse

2002-09-01

GK Dra has been discovered by the Hipparcos mission as a 17 days eclipsing binary. We present here the first ground-based study of this star, based on extensive BV photoelectric photometry. We found a period of 9.974 days, equal depth primary and secondary eclipse (m=0.35 mag), no color variation in eclipse, and one of the components being a Sct star with an amplitude of 0.04 mag and a period of about 2.7 hours.

The High Time Resolution Universe Pulsar Survey - XII. Galactic plane acceleration search and the discovery of 60 pulsars

NASA Astrophysics Data System (ADS)

Ng, C.; Champion, D. J.; Bailes, M.; Barr, E. D.; Bates, S. D.; Bhat, N. D. R.; Burgay, M.; Burke-Spolaor, S.; Flynn, C. M. L.; Jameson, A.; Johnston, S.; Keith, M. J.; Kramer, M.; Levin, L.; Petroff, E.; Possenti, A.; Stappers, B. W.; van Straten, W.; Tiburzi, C.; Eatough, R. P.; Lyne, A. G.

2015-07-01

We present initial results from the low-latitude Galactic plane region of the High Time Resolution Universe pulsar survey conducted at the Parkes 64-m radio telescope. We discuss the computational challenges arising from the processing of the terabyte-sized survey data. Two new radio interference mitigation techniques are introduced, as well as a partially coherent segmented acceleration search algorithm which aims to increase our chances of discovering highly relativistic short-orbit binary systems, covering a parameter space including potential pulsar-black hole binaries. We show that under a constant acceleration approximation, a ratio of data length over orbital period of ≈0.1 results in the highest effectiveness for this search algorithm. From the 50 per cent of data processed thus far, we have redetected 435 previously known pulsars and discovered a further 60 pulsars, two of which are fast-spinning pulsars with periods less than 30 ms. PSR J1101-6424 is a millisecond pulsar whose heavy white dwarf (WD) companion and short spin period of 5.1 ms indicate a rare example of full-recycling via Case A Roche lobe overflow. PSR J1757-27 appears to be an isolated recycled pulsar with a relatively long spin period of 17 ms. In addition, PSR J1244-6359 is a mildly recycled binary system with a heavy WD companion, PSR J1755-25 has a significant orbital eccentricity of 0.09 and PSR J1759-24 is likely to be a long-orbit eclipsing binary with orbital period of the order of tens of years. Comparison of our newly discovered pulsar sample to the known population suggests that they belong to an older population. Furthermore, we demonstrate that our current pulsar detection yield is as expected from population synthesis.

Recent Observations of the Neglected Southern Eclipsing Binary Systems V343 Cen, UY Mus, HT Aps, and V1961 Sgr

NASA Astrophysics Data System (ADS)

Faulkner, D. R.; Samec, R. G.; Stoddard, M. L.; McKenzie, R.; Rebar, D.; Lavoie, G. D.; Moody, S.; Miller, J.; Van Hamme, W.

2002-12-01

As a part of our continuing search for solar type binaries with impacting gas streams, we present light curves of V343 Cen, UY Mus, HT Aps, and V1961 Sgr. These are all neglected variables whose observing histories show little or no observations since their discovery. The CCD observations were taken at the 0.9-m at CTI0 in the UBVRI Johnson-Cousins system. The observations were taken in on 2002, May 31-June 8 and 2001, May 16 - 23 respectively. UY Mus is a near contact binary with a large difference in eclipse depths of V = 0.67 mag. Otherwise the curve appears symmetric. The times of minimum light determined from our data are HJD Min I = 242047.62316(6) and Min II = 2452050.4874(3) where the value in parentheses is the standard error in the last decimal place. V1961 Sgr (GCVS 6848 485) is a W UMa binary with a difference in eclipse depths of V = 0.11 mag and a possible variable spot area causing a V = 0.04 mag variation in MAX I from night to night. HT Aps is a near contact solar type binary with a large difference in eclipse depths of V= 0.47 mag and a somewhat asymmetric (difference in maxima, V= 0.4 mag) light curve. It is a possibly a candidate for a binary with a gas stream. One time of minimum light determined from our data is HJD Min I = 2452331.63725 (12). V343 Cen is a near contact binary with a large difference in eclipse depths of V= 0.42 mag and distortions that give evidence of a gas stream collision. The difference in maxima is V = 0.07 mag. The curve shows little variation over the 4 day interval of observation. Light curves analyses, new period determinations and photometric data will be presented for these variables. Acknowledgements: We wish to thank the American Astronomical Society for their continued support of our undergraduate research programs through their small research grants. Faulkner and Samec were visiting Astronomers, Cerro Tololo InterAmerican Observatory, National Optical Astronomical Observatories, which are operated by the Association of Universities for Research in Astronomy, Inc. under contract with the National Science Foundation.

Binary model of Circinus X-1. I - Eccentricity from combined X-ray and radio observations

NASA Technical Reports Server (NTRS)

Murdin, P.; Jauncey, D. L.; Lerche, I.; Nicolson, G. D.; Kaluzienski, L. J.; Holt, S. S.; Haynes, R. F.

1980-01-01

A binary star model is used to account for the 16.59-d flaring behavior of the X-ray emission from Circinus X-1. The orbital eccentricity of 0.8 + or - 0.1 is derived from the X-ray light curve by assuming that the sharp X-ray cut-off every 16.59-d is a result of bound-free absorption in the primary star's stellar wind. The shape of the light curve has changed over the last eight years, and this is interpreted as due to orbital precession of the binary system. Simultaneous radio and X-ray observations of the flare from Circinus X-1 on February 1-5, 1978 are reported. These are accounted for within the framework of the model. The radio observations at 5 GHz are used independently to derive a high value of the orbital eccentricity (e = 0.7).

DOE Office of Scientific and Technical Information (OSTI.GOV)

Key, Joey Shapiro; Cornish, Neil J.

The Laser Interferometer Space Antenna (LISA) is designed to detect gravitational wave signals from astrophysical sources, including those from coalescing binary systems of compact objects such as black holes. Colliding galaxies have central black holes that sink to the center of the merged galaxy and begin to orbit one another and emit gravitational waves. Some galaxy evolution models predict that the binary black hole system will enter the LISA band with significant orbital eccentricity, while other models suggest that the orbits will already have circularized. Using a full 17 parameter waveform model that includes the effects of orbital eccentricity, spinmore » precession, and higher harmonics, we investigate how well the source parameters can be inferred from simulated LISA data. Defining the reference eccentricity as the value one year before merger, we find that for typical LISA sources, it will be possible to measure the eccentricity to an accuracy of parts in a thousand. The accuracy with which the eccentricity can be measured depends only very weakly on the eccentricity, making it possible to distinguish circular orbits from those with very small eccentricities. LISA measurements of the orbital eccentricity can help constraints theories of galaxy mergers in the early universe. Failing to account for the eccentricity in the waveform modeling can lead to a loss of signal power and bias the estimation of parameters such as the black hole masses and spins.« less

Fundamental parameters and origin of the very eccentric binary 41 Dra

NASA Astrophysics Data System (ADS)

Tokovinin, A.; Balega, Y. Y.; Pluzhnik, E. A.; Shatsky, N. I.; Gorynya, N. A.; Weigelt, G.

2003-10-01

The evolutionary status and origin of the most eccentric known binary in a quadruple system, 41 Dra (e=0.9754, period 3.413 yr), are discussed. New observations include the much improved combined speckle-interferometric orbit, resolved photometry of the components and their spectroscopic analysis. The age of the system is 2.5 +/- 0.2 Gyr; all four components are likely coeval. The high eccentricity of the orbit together with known age and masses provide a constraint on the tidal circularization theory: it seems that the eccentric orbit survived because the convective zones of the F-type dwarfs were very thin. Now as the components of 41 Dra are leaving the Main Sequence, their increased interaction at each periastron passage may result in detectable changes in period and eccentricity. Tables 1, 2, and 3 are only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/409/245

A simultaneous spectroscopic and photometric study of two eclipsing binaries: V566 Oph and V972 Her

NASA Astrophysics Data System (ADS)

Selam, S. O.; Esmer, E. M.; Şenavcı, H. V.; Bahar, E.; Yörükoğlu, O.; Yılmaz, M.; Baştürk, Ö.

2018-02-01

In this study, we have performed simultaneous solutions of light and radial velocity curves of two eclipsing binary systems, V566 Oph and V972 Her. We observed both systems spectroscopically with a very recently installed spectrograph on the 40 cm telescope, T40, located in Ankara University Kreiken Observatory (AUKR), for the first time. We made use of the photometric data from the Hipparcos satellite for V972 Her, while we obtained the photometric observations of V566 Oph by using the 35 cm telescope, T35, located also in our observatory campus. We derived the absolute parameters for both systems and discussed their evolutionary states. In addition to the simultaneous analysis, we have also analyzed the change in mid-eclipse times for V566 Oph, and found cyclic variations, for which we have discussed light-time effect and magnetic activity as their potential origin, superimposed on a secular change due to a mass transfer between the components of the binary.

K2 Variable Catalogue: Variable stars and eclipsing binaries in K2 campaigns 1 and 0

NASA Astrophysics Data System (ADS)

Armstrong, D. J.; Kirk, J.; Lam, K. W. F.; McCormac, J.; Walker, S. R.; Brown, D. J. A.; Osborn, H. P.; Pollacco, D. L.; Spake, J.

2015-07-01

Aims: We have created a catalogue of variable stars found from a search of the publicly available K2 mission data from Campaigns 1 and 0. This catalogue provides the identifiers of 8395 variable stars, including 199 candidate eclipsing binaries with periods up to 60 d and 3871 periodic or quasi-periodic objects, with periods up to 20 d for Campaign 1 and 15 d for Campaign 0. Methods: Lightcurves are extracted and detrended from the available data. These are searched using a combination of algorithmic and human classification, leading to a classifier for each object as an eclipsing binary, sinusoidal periodic, quasi periodic, or aperiodic variable. The source of the variability is not identified, but could arise in the non-eclipsing binary cases from pulsation or stellar activity. Each object is cross-matched against variable star related guest observer proposals to the K2 mission, which specifies the variable type in some cases. The detrended lightcurves are also compared to lightcurves currently publicly available. Results: The resulting catalogue gives the ID, type, period, semi-amplitude, and range of the variation seen. We also make available the detrended lightcurves for each object. The catalogue is available at http://deneb.astro.warwick.ac.uk/phrlbj/k2varcat/ and at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/579/A19

A matched filter method for ground-based sub-noise detection of terrestrial extrasolar planets in eclipsing binaries: application to CM Draconis.

PubMed

Jenkins, J M; Doyle, L R; Cullers, D K

1996-02-01

The photometric detection of extrasolar planets by transits in eclipsing binary systems can be significantly improved by cross-correlating the observational light curves with synthetic models of possible planetary transit features, essentially a matched filter approach. We demonstrate the utility and application of this transit detection algorithm for ground-based detections of terrestrial-sized (Earth-to-Neptune radii) extrasolar planets in the dwarf M-star eclipsing binary system CM Draconis. Preliminary photometric observational data of this system demonstrate that the observational noise is well characterized as white and Gaussian at the observational time steps required for precision photometric measurements. Depending on planet formation scenarios, terrestrial-sized planets may form quite close to this low-luminosity system. We demonstrate, for example, that planets as small as 1.4 Earth radii with periods on the order of a few months in the CM Draconis system could be detected at the 99.9% confidence level in less than a year using 1-m class telescopes from the ground. This result contradicts commonly held assumptions limiting present ground-based efforts to, at best, detections of gas giant planets after several years of observation. This method can be readily extended to a number of other larger star systems with the utilization of larger telescopes and longer observing times. Its extension to spacecraft observations should also allow the determination of the presence of terrestrial-sized planets in nearly 100 other known eclipsing binary systems.

A matched filter method for ground-based sub-noise detection of terrestrial extrasolar planets in eclipsing binaries: application to CM Draconis

NASA Technical Reports Server (NTRS)

Jenkins, J. M.; Doyle, L. R.; Cullers, D. K.

1996-01-01

The photometric detection of extrasolar planets by transits in eclipsing binary systems can be significantly improved by cross-correlating the observational light curves with synthetic models of possible planetary transit features, essentially a matched filter approach. We demonstrate the utility and application of this transit detection algorithm for ground-based detections of terrestrial-sized (Earth-to-Neptune radii) extrasolar planets in the dwarf M-star eclipsing binary system CM Draconis. Preliminary photometric observational data of this system demonstrate that the observational noise is well characterized as white and Gaussian at the observational time steps required for precision photometric measurements. Depending on planet formation scenarios, terrestrial-sized planets may form quite close to this low-luminosity system. We demonstrate, for example, that planets as small as 1.4 Earth radii with periods on the order of a few months in the CM Draconis system could be detected at the 99.9% confidence level in less than a year using 1-m class telescopes from the ground. This result contradicts commonly held assumptions limiting present ground-based efforts to, at best, detections of gas giant planets after several years of observation. This method can be readily extended to a number of other larger star systems with the utilization of larger telescopes and longer observing times. Its extension to spacecraft observations should also allow the determination of the presence of terrestrial-sized planets in nearly 100 other known eclipsing binary systems.

Hidden slow pulsars in binaries

NASA Technical Reports Server (NTRS)

Tavani, Marco; Brookshaw, Leigh

1993-01-01

The recent discovery of the binary containing the slow pulsar PSR 1718-19 orbiting around a low-mass companion star adds new light on the characteristics of binary pulsars. The properties of the radio eclipses of PSR 1718-19 are the most striking observational characteristics of this system. The surface of the companion star produces a mass outflow which leaves only a small 'window' in orbital phase for the detection of PSR 1718-19 around 400 MHz. At this observing frequency, PSR 1718-19 is clearly observable only for about 1 hr out of the total 6.2 hr orbital period. The aim of this Letter is twofold: (1) to model the hydrodynamical behavior of the eclipsing material from the companion star of PSR 1718-19 and (2) to argue that a population of binary slow pulsars might have escaped detection in pulsar surveys carried out at 400 MHz. The possible existence of a population of partially or totally hidden slow pulsars in binaries will have a strong impact on current theories of binary evolution of neutron stars.

W UMa Type Eclipsing Binary VW Cep

NASA Astrophysics Data System (ADS)

Kang, Bong-Seok; Lee, Yong-Sam; Jeong, Jang-Hae

2000-06-01

A total of 1,018 observations (509 in B, 509 in V ) of the eclipsing binary VW Cep was made during 7 nights from April through May in 1999 at Sobaeksan Optical Astronomy Observatory, using the CCD camera attached to the 61cm telescope. A time of minimum light of HJD2451327.2282 was determined from our data, and we constructed BV light curves with the data. Using Wilson-Devinney's binary model, we analized the light curves. The absolute dimension of M1 = 0.95Msolar, M2 = 0.33Msolar, R1 = 1.02Rsolar, R2 = 0.66Rsolar of the VW Cep system were derived from our light curve solution and Kaszas et al. (1998) spectroscoppic rsult.

A Photometric Study of Three Eclipsing Binary Stars (Poster abstract)

NASA Astrophysics Data System (ADS)

Ryan, A.

2016-12-01

(Abstract only) As part of a program to study eclipsing binary stars that exhibit the O'Connell Effect (OCE) we are observing a selection of binary stars in a long term study. The OCE is a difference in maximum light across the ligthcurve possibly cause by starspots. We observed for 7 nights at McDonald Observatory using the 30-inch telescope in July 2015, and used the same telescope remotely for a total of 20 additional nights in August, October, December, and January. We will present lightcurves for three stars from this study, characterize the OCE for these stars, and present our model results for the physical parameters of the star making up each of these systems.

A New Light Curve and Analysis of the Long Period Eclipsing Binary BF Draconis

NASA Astrophysics Data System (ADS)

Wolf, G. W.; Craig, L. E.; Caffey, J. F.

1999-01-01

The star BF Draconis was found to be an eclipsing binary by Strohmeier, Knigge and Ott (1962) and originally thought to be an Algol-type system with a period of 5.6 days. A spectrographic study by Imbert (1985) showed that the period was actually double this value and that the system consisted of two well-separated, almost-equal F-type stars in elliptical orbit. Diethelm, Wolf and Agerer (1993) later published a preliminary light curve of this system showing minima of unequal depth and width with a displaced secondary, confirming the elliptical orbit but disagreeing with Imbert on the specific orbital parameters. As a part of our long-term program of obtaining improved light curves of double-lined spectroscopic and eclipsing binaries, we have observed BF Draconis for the past four years using the 0.4 meter telescope at the Baker Observatory of Southwest Missouri State University. Complete light curves in the Cousins BVRI passbands have been obtained with our Photometrics CCD system, and a new model and orbital parameters for the binary have been determined using the Wilson-Devinney program. This research has been supported by NSF Grants AST-9315061 and AST-9605822 and NASA Grant NGT5-40060.

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

NASA Astrophysics Data System (ADS)

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 minutes was determined for the secondary eclipse and the light curve solution. Additional and more detailed information is given in the poster paper.

HD 66051: the first eclipsing binary hosting an early-type magnetic star

NASA Astrophysics Data System (ADS)

Kochukhov, O.; Johnston, C.; Alecian, E.; Wade, G. A.

2018-05-01

Early-type magnetic stars are rarely found in close binary systems. No such objects were known in eclipsing binaries prior to this study. Here we investigated the eclipsing, spectroscopic double-lined binary HD 66051, which exhibits out-of-eclipse photometric variations suggestive of surface brightness inhomogeneities typical of early-type magnetic stars. Using a new set of high-resolution spectropolarimetric observations, we discovered a weak magnetic field on the primary and found intrinsic, element-dependent variability in its spectral lines. The magnetic field structure of the primary is dominated by a nearly axisymmetric dipolar component with a polar field strength Bd ≈ 600 G and an inclination with respect to the rotation axis of βd = 13°. A weaker quadrupolar component is also likely to be present. We combined the radial velocity measurements derived from our spectra with archival optical photometry to determine fundamental masses (3.16 and 1.75 M⊙) and radii (2.78 and 1.39 R⊙) with a 1-3% precision. We also obtained a refined estimate of the effective temperatures (13000 and 9000 K) and studied chemical abundances for both components with the help of disentangled spectra. We demonstrate that the primary component of HD 66051 is a typical late-B magnetic chemically peculiar star with a non-uniform surface chemical abundance distribution. It is not an HgMn-type star as suggested by recent studies. The secondary is a metallic-line star showing neither a strong, global magnetic field nor intrinsic spectral variability. Fundamental parameters provided by our work for this interesting system open unique possibilities for probing interior structure, studying atomic diffusion, and constraining binary star evolution.

An eclipsing post common-envelope system consisting of a pulsating hot subdwarf B star and a brown dwarf companion

NASA Astrophysics Data System (ADS)

Schaffenroth, V.; Barlow, B. N.; Drechsel, H.; Dunlap, B. H.

2015-04-01

Hot subdwarf B stars (sdBs) are evolved, core helium-burning objects located on the extreme horizontal branch. Their formation history is still puzzling because the sdB progenitors must lose nearly all of their hydrogen envelope during the red-giant phase. About half of the known sdBs are in close binaries with periods from 1.2 h to a few days, which implies that they experienced a common-envelope phase. Eclipsing hot subdwarf binaries (also called HW Virginis systems) are rare but important objects for determining fundamental stellar parameters. Even more significant and uncommon are those binaries containing a pulsating sdB, since the mass can be determined independently by asteroseismology. Here we present a first analysis of the eclipsing hot subdwarf binary V2008-1753. The light curve shows a total eclipse, a prominent reflection effect, and low-amplitude pulsations with periods from 150 to 180 s. An analysis of the light- and radial velocity curves indicates a mass ratio close to q = 0.146, an radial velocity semi-amplitude of K = 54.6 km s-1, and an inclination of i = 86.8°. Combining these results with our spectroscopic determination of the surface gravity, log g = 5.83, the best-fitting model yields an sdB mass of 0.47 M⊙ and a companion mass of 69 MJup. Because the latter mass is below the hydrogen-burning limit, V2008-1753 represents the first HW Vir system that is known to consist of a pulsating sdB and a brown dwarf companion. Consequently, it holds strong potential for better constraining models of sdB binary evolution and asteroseismology.

TESTING THE ASTEROSEISMIC SCALING RELATIONS FOR RED GIANTS WITH ECLIPSING BINARIES OBSERVED BY KEPLER

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gaulme, P.; McKeever, J.; Jackiewicz, J.

2016-12-01

Given the potential of ensemble asteroseismology for understanding fundamental properties of large numbers of stars, it is critical to determine the accuracy of the scaling relations on which these measurements are based. From several powerful validation techniques, all indications so far show that stellar radius estimates from the asteroseismic scaling relations are accurate to within a few percent. Eclipsing binary systems hosting at least one star with detectable solar-like oscillations constitute the ideal test objects for validating asteroseismic radius and mass inferences. By combining radial velocity (RV) measurements and photometric time series of eclipses, it is possible to determine themore » masses and radii of each component of a double-lined spectroscopic binary. We report the results of a four-year RV survey performed with the échelle spectrometer of the Astrophysical Research Consortium’s 3.5 m telescope and the APOGEE spectrometer at Apache Point Observatory. We compare the masses and radii of 10 red giants (RGs) obtained by combining radial velocities and eclipse photometry with the estimates from the asteroseismic scaling relations. We find that the asteroseismic scaling relations overestimate RG radii by about 5% on average and masses by about 15% for stars at various stages of RG evolution. Systematic overestimation of mass leads to underestimation of stellar age, which can have important implications for ensemble asteroseismology used for Galactic studies. As part of a second objective, where asteroseismology is used for understanding binary systems, we confirm that oscillations of RGs in close binaries can be suppressed enough to be undetectable, a hypothesis that was proposed in a previous work.« less

The Optical Gravitational Lensing Experiment. Ellipsoidal Variability of Red Giants in the Large Magellanic Cloud

NASA Astrophysics Data System (ADS)

Soszynski, I.; Udalski, A.; Kubiak, M.; Szymanski, M. K.; Pietrzynski, G.; Zebrun, K.; Szewczyk, O.; Wyrzykowski, L.; Dziembowski, W. A.

2004-12-01

We used the OGLE-II and OGLE-III photometry of red giants in the Large Magellanic Cloud to select and study objects revealing ellipsoidal variability. We detected 1546 candidates for long period ellipsoidal variables and 121 eclipsing binary systems with clear ellipsoidal modulation. The ellipsoidal red giants follow a period--luminosity (PL) relationship (sequence E), and the scatter of the relation is correlated with the amplitude of variability: the larger the amplitude, the smaller the scatter. We note that some of the ellipsoidal candidates exhibit simultaneously OGLE Small Amplitude Red Giants pulsations. Thus, in some cases the Long Secondary Period (LSP) phenomenon can be explained by the ellipsoidal modulation. We also select about 1600 red giants with distinct LSP, which are not ellipsoidal variables. We discover that besides the sequence D in the PL diagram known before, the LSP giants form additional less numerous sequence for longer periods. We notice that the PL sequence of the ellipsoidal candidates is a direct continuation of the LSP sequence toward fainter stars, what might suggest that the LSP phenomenon is related to binarity but there are strong arguments against such a possibility. About 10% of the presented light curves reveal clear deformation by the eccentricity of the system orbits. The largest estimated eccentricity in our sample is about 0.4. All presented data, including individual BVI observations and finding charts are available from the OGLE Internet archive.

SS Bootis - A totally eclipsing binary of the RS CVn type

NASA Technical Reports Server (NTRS)

Vaucher, C. A.; Africano, J. L.; Henry, G. W.; Hall, D. S.; Wilson, J. W.

1983-01-01

Photoelectric photometry gathered for SS Bootis over the 1976-1981 period shows a distortion wave amplitude variation from 0.05 to 0.20 mag, with no apparent pattern. From the rectified light curve, a new time of midprimary eclipse was found to be 2444332.0335 + or - 0.0005 days. Solutions of the primary eclipse data, rectified for star spots as well as for ellipticity and reflection, are presented.

Asiago eclipsing binaries program IV. SZ Camelopardalis, a β Cephei pulsator in a quadruple, eclipsing system

NASA Astrophysics Data System (ADS)

Tamajo, E.; Munari, U.; Siviero, A.; Tomasella, L.; Dallaporta, S.

2012-03-01

We present a spectroscopic and photometric analysis of the multiple system and early-type eclipsing binary SZ Cam (O9 IV + B0.5 V), which consists of an eclipsing SB2 pair of orbital period P = 2.7 days in a long orbit (~55 yrs) around a non-eclipsing SB1 pair of orbital period P = 2.8 days. We have reconstructed the spectra of the individual components of SZ Cam from the observed composite spectra using the technique of spectral disentangling. We used them together with extensive and accurate BVIC CCD photometry to obtain an orbital solution. Our photometry revealed the presence of a β Cep variable in the SZ Cam hierarchical system, probably located within the non-eclipsing SB1 pair. The pulsation period is (0.33265 ± 0.00005) days and the observed total amplitude in the B band is (0.0105 ± 0.0005) mag. NLTE analysis of the disentangled spectra provided atmospheric parameters for all three components, consistent with those derived from orbital solution. Full Table 3 is only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/539/A139

Analysis of GSC 2475-1587 and GSC 841-277: Two Eclipsing Binary Stars Found During Asteroid Lightcurve Observations

NASA Astrophysics Data System (ADS)

Stephens, R. D.; Warner, B. D.

2006-05-01

When observing asteroids we select from two to five comparison stars for differential photometry, taking the average value of the comparisons for the single value to be subtracted from the value for the asteroid. As a check, the raw data of each comparison star are plotted as is the difference between any single comparison and the average of the remaining stars in the set. On more than one occasion, we have found that at least one of the comparisons was variable. In two instances, we took time away from our asteroid lightcurve work to determine the period of the two binaries and attempted to model the system using David Bradstreet's Binary Maker 3. Unfortunately, neither binary showed a total eclipse. Therefore, our results are not conclusive and present only one of many possibilities.

WW Geminorum: An early B-type eclipsing binary evolving into the contact phase

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yang, Y.-G.; Dai, H.-F.; Yin, X.-G.

2014-11-01

WW Gem is a B-type eclipsing binary with a period of 1.2378 days. The CCD photometry of this binary was performed in 2013 December using the 85 cm telescope at the Xinglong Stations of the National Astronomical Observatories of China. Using the updated W-D program, the photometric model was deduced from the VRI light curves. The results imply that WW Gem is a near-contact eclipsing binary whose primary component almost fills its Roche lobe. The photometric mass ratio is q {sub ph} = 0.48(± 0.05). All collected times of minimum light, including two new ones, were used for the periodmore » studies. The orbital period changes of WW Gem could be described by an upward parabola, possibly overlaid by a light-time orbit with a period of P {sub mod} = 7.41(± 0.04) yr and a semi-amplitude of A = 0.0079 days(± 0.0005 days), respectively. This kind of cyclic oscillation may be attributed to the light-travel time effect via the third body. The long-term period increases at a rate of dP/dt = +3.47(±0.04) × 10{sup –8} day yr{sup –1}, which may be explained by the conserved mass transfer from the less massive component to the more massive one. With mass transfer, the massive binary WW Gem may be evolving into a contact binary.« less

The MUCHFUSS photometric campaign

NASA Astrophysics Data System (ADS)

Schaffenroth, V.; Geier, S.; Heber, U.; Gerber, R.; Schneider, D.; Ziegerer, E.; Cordes, O.

2018-06-01

Hot subdwarfs (sdO/Bs) are the helium-burning cores of red giants, which have lost almost all of their hydrogen envelope. This mass loss is often triggered by common envelope interactions with close stellar or even substellar companions. Cool companions like late-type stars or brown dwarfs are detectable via characteristic light-curve variations like reflection effects and often also eclipses. To search for such objects, we obtained multi-band light curves of 26 close sdO/B binary candidates from the MUCHFUSS project with the BUSCA instrument. We discovered a new eclipsing reflection effect system (P = 0.168938 d) with a low-mass M dwarf companion (0.116 M⊙). Three more reflection effect binaries found in the course of the campaign have already been published; two of them are eclipsing systems, and in one system only showing the reflection effect but no eclipses, the sdB primary is found to be pulsating. Amongst the targets without reflection effect a new long-period sdB pulsator was discovered and irregular light variations were found in two sdO stars. The found light variations allowed us to constrain the fraction of reflection effect binaries and the substellar companion fraction around sdB stars. The minimum fraction of reflection effect systems amongst the close sdB binaries might be greater than 15% and the fraction of close substellar companions in sdB binaries may be as high as 8.0%. This would result in a close substellar companion fraction to sdB stars of about 3%. This fraction is much higher than the fraction of brown dwarfs around possible progenitor systems, which are solar-type stars with substellar companions around 1 AU, as well as close binary white dwarfs with brown dwarf companions. This might suggest that common envelope interactions with substellar objects are preferentially followed by a hot subdwarf phase.

Eclipse timings of the low-mass X-ray binary EXO 0748-676: Statistical arguments against orbital period changes

NASA Technical Reports Server (NTRS)

Hertz, Paul; Wood, Kent S.; Cominsky, Lynn

1995-01-01

EXO 0748-676, an eclipsing low-mass X-ray binary, is one of only about four or five low-mass X-ray binaries for which orbital period evolution has been reported. We observed a single eclipse egress with ROSAT . The time of this egress is consistent with the apparent increase in P(sub orb) previously reported on the basis of EXOSAT and Ginga observations. Standard analysis, in which O-C (observed minus calculated) timing residuals are examined for deviations from a constant period, implicitly assume that the only uncertainty in each residual is measurement error and that these errors are independent. We argue that the variable eclipse durations and profiles observed in EXO 0748-676 imply that there is an additional source of uncertainty in timing measurements, that this uncertainty is intrinsic to the binary system, and that it is correlated from observation to observation with a variance which increases as a function of the number of binary cycles between observations. This intrinsic variability gives rise to spurious trends in O-C residuals which are misinterpreted as changes in the orbital period. We describe several statistics tests which can be used to test for the presence of intrinsic variability. We apply those statistical tests which are suitable to the EXO 0748-676 observations. The apparent changes in the orbital period of EXO 0748-676 can be completely accounted for by intrinsic variability with an rms variability of approximately 0.35 s per orbital cycle. The variability appears to be correlated from cycle-to-cycle on timescales of less than 1 yr. We suggest that the intrinsic variability is related to slow changes in either the source's X-ray luminosity or the structure of the companion star's atmosphere. We note that several other X-ray binaries and cataclysmic variables have previously reported orbital period changes which may also be due to intrinsic variability rather than orbital period evolution.

Line Identifications in the Far Ultraviolet Spectrum of the Eclipsing Binary System 31 Cygni

NASA Astrophysics Data System (ADS)

Hagen Bauer, Wendy; Bennett, P. D.

2011-05-01

The eclipsing binary system 31 Cygni (K4 Ib + B3 V) was observed at several phases with the Far Ultraviolet Spectrosocopic Explorer (FUSE) satellite. During total eclipse, a rich emission spectrum was observed, produced by scattering of hot star photons in the extended wind of the K supergiant. The system was observed during deep chromospheric eclipse, and 2.5 months after total eclipse ended. We present an atlas of line identifications in these spectra. During total eclipse, emission features from C II , C III, N I, N II, N III, O I, Si II, P II, P III, S II, S III, Ar I, Cr III, Fe II, Fe III, and Ni II were detected. The strongest emission features arise from N II. These lines appear strongly in absorption during chromospheric eclipse, and even 2.5 months after total eclipse, the absorption bottoms out on the underlying emission seen during total eclipse. The second strongest features in the emission spectrum arise from Fe III. Any chromospheric Fe III absorption is buried within strong chromospheric absorption from other species, mainly Fe II. The emission profiles of most of the doubly-ionized species are red-shifted relative to the systemic velocity, with asymmetric profiles with a steeper long-wavelength edge. Emission profiles from singly-ionized species tend to be more symmetric and centered near the systemic velocity. In deep chromospheric eclipse, absorption features are seen from neutral and singly-ionized species, arising from lower levels up to 3 eV. Many strong chromospheric features are doubled in the observation obtained during egress from eclipse. The 31 Cygni spectrum taken 2.5 months after total eclipse ended ws compared to single-star B spectra from the FUSE archives. There was still some additional chromospheric absorption from strong low-excitation Fe II, O I and Ar I.

Timing of AB And eclipses

NASA Astrophysics Data System (ADS)

Kozyreva, V. S.; Ibrahimov, M. A.; Gaynullina, E. R.; Karimov, R. G.; Hafizov, B. M.; Satovskii, B. L.; Krushevska, V. N.; Kuznyetsova, Yu. G.; Bogomazov, A. I.; Irsmambetova, T. R.; Tutukov, A. V.

2018-01-01

This study aims timing the eclipses of the short period low mass binary star AB And. The times of minima are taken from the literature and from our observations in October 2013 (22 times of minima) and in August 2014 (23 times of minima). We find and discuss an inaccuracy in the determination of the types of minima in the previous investigation by Li et al. (2014). We study the secular evolution of the central binary's orbital period and the possibility of the existence of third and fourth companions in the system.

LX Persei, an eclipsing binary with H and K emission

NASA Technical Reports Server (NTRS)

Weiler, E. J.

1974-01-01

The masses and MK classes were calculated for the eclipsing spectroscopic binary LX Persei. Its spectrum shows strong H and K emission and doubled lines in the photographic region. The Ca II emission velocity shifts vary in phase with the secondary's absorption lines and are presumably associated with this component. The stars are tentatively classed as G0 V and K0 IV, and the cooler component is the more massive by a ratio of 0.96. The system has a period of 8.0 days.

Physical implications of the eclipsing binary pulsar

NASA Technical Reports Server (NTRS)

Wasserman, Ira; Cordes, James M.

1988-01-01

The observed characteristics of the msec pulsar P1957+20, discovered in an eclipsing binary by Fruchter et al. (1988), are considered theoretically. Model equations for the stellar wind and optical emission are derived and used to estimate the effective temperature and optical luminosity associated with wind excitation; then the energy levels required to generate such winds are investigated. The color temperature of the pulsar-heated stellar surface calculated under the assumption of adiabatic expansion is 1000-10,000 K, in good agreement with the observational estimate of 5500 K.

A Catalog of Eclipsing Binaries and Variable Stars Observed with ASTEP 400 from Dome C, Antarctica

NASA Astrophysics Data System (ADS)

Chapellier, E.; Mékarnia, D.; Abe, L.; Guillot, T.; Agabi, K.; Rivet, J.-P.; Schmider, F.-X.; Crouzet, N.; Aristidi, E.

2016-10-01

We used the large photometric database of the ASTEP program, whose primary goal was to detect exoplanets in the southern hemisphere from Antarctica, to search for eclipsing binaries (EcBs) and variable stars. 673 EcBs and 1166 variable stars were detected, including 31 previously known stars. The resulting online catalogs give the identification, the classification, the period, and the depth or semi-amplitude of each star. Data and light curves for each object are available at http://astep-vo.oca.eu.

Orbital Characteristics of the Subdwarf-B and F V Star Binary EC 20117-4014 (=V4640 Sgr)

NASA Astrophysics Data System (ADS)

Otani, T.; Oswalt, T. D.; Lynas-Gray, A. E.; Kilkenny, D.; Koen, C.; Amaral, M.; Jordan, R.

2018-06-01

Among the competing evolution theories for subdwarf-B (sdB) stars is the binary evolution scenario. EC 20117-4014 (=V4640 Sgr) is a spectroscopic binary system consisting of a pulsating sdB star and a late F main-sequence companion; however, the period and the orbit semimajor axes have not been precisely determined. This paper presents orbital characteristics of the EC 20117-4014 binary system using 20 years of photometric data. Periodic observed minus calculated (O–C) variations were detected in the two highest-amplitude pulsations identified in the EC 20117-4014 power spectrum, indicating the binary system’s precise orbital period (P = 792.3 days) and the light-travel-time amplitude (A = 468.9 s). This binary shows no significant orbital eccentricity, and the upper limit of the eccentricity is 0.025 (using 3σ as an upper limit). This upper limit of the eccentricity is the lowest among all wide sdB binaries with known orbital parameters. This analysis indicated that the sdB is likely to have lost its hydrogen envelope through stable Roche lobe overflow, thus supporting hypotheses for the origin of sdB stars. In addition to those results, the underlying pulsation period change obtained from the photometric data was \\dot{P} = 5.4 (±0.7) × 10‑14 d d‑1, which shows that the sdB is just before the end of the core helium-burning phase.

A SEARCH FOR X-RAY EMISSION FROM COLLIDING MAGNETOSPHERES IN YOUNG ECCENTRIC STELLAR BINARIES

DOE Office of Scientific and Technical Information (OSTI.GOV)

Getman, Konstantin V.; Broos, Patrick S.; Kóspál, Ágnes

Among young binary stars whose magnetospheres are expected to collide, only two systems have been observed near periastron in the X-ray band: the low-mass DQ Tau and the older and more massive HD 152404. Both exhibit elevated levels of X-ray emission at periastron. Our goal is to determine whether colliding magnetospheres in young high-eccentricity binaries commonly produce elevated average levels of X-ray activity. This work is based on Chandra snapshots of multiple periastron and non-periastron passages in four nearby young eccentric binaries (Parenago 523, RX J1622.7-2325 Nw, UZ Tau E, and HD 152404). We find that for the merged samplemore » of all four binaries the current X-ray data show an increasing average X-ray flux near periastron (at a ∼2.5-sigma level). Further comparison of these data with the X-ray properties of hundreds of young stars in the Orion Nebula Cluster, produced by the Chandra Orion Ultradeep Project (COUP), indicates that the X-ray emission from the merged sample of our binaries cannot be explained within the framework of the COUP-like X-ray activity. However, due to the inhomogeneities of the merged binary sample and the relatively low statistical significance of the detected flux increase, these findings are regarded as tentative only. More data are needed to prove that the flux increase is real and is related to the processes of colliding magnetospheres.« less

A Search For X-Ray Emission From Colliding Magnetospheres In Young Eccentric Stellar Binaries

NASA Astrophysics Data System (ADS)

Getman, Konstantin V.; Broos, Patrick S.; Kóspál, Ágnes; Salter, Demerese M.; Garmire, Gordon P.

2016-12-01

Among young binary stars whose magnetospheres are expected to collide, only two systems have been observed near periastron in the X-ray band: the low-mass DQ Tau and the older and more massive HD 152404. Both exhibit elevated levels of X-ray emission at periastron. Our goal is to determine whether colliding magnetospheres in young high-eccentricity binaries commonly produce elevated average levels of X-ray activity. This work is based on Chandra snapshots of multiple periastron and non-periastron passages in four nearby young eccentric binaries (Parenago 523, RX J1622.7-2325 Nw, UZ Tau E, and HD 152404). We find that for the merged sample of all four binaries the current X-ray data show an increasing average X-ray flux near periastron (at a ˜2.5-sigma level). Further comparison of these data with the X-ray properties of hundreds of young stars in the Orion Nebula Cluster, produced by the Chandra Orion Ultradeep Project (COUP), indicates that the X-ray emission from the merged sample of our binaries cannot be explained within the framework of the COUP-like X-ray activity. However, due to the inhomogeneities of the merged binary sample and the relatively low statistical significance of the detected flux increase, these findings are regarded as tentative only. More data are needed to prove that the flux increase is real and is related to the processes of colliding magnetospheres.

Period changes of the long-period cataclysmic binary EX Draconis

NASA Astrophysics Data System (ADS)

Pilarčík, L.; Wolf, M.; Dubovský, P. A.; Hornoch, K.; Kotková, L.

2012-03-01

The cataclysmic variable star EX Dra is a relatively faint but frequently investigated eclipsing dwarf nova. In total 35 new eclipses were measured photometrically as part of our long-term monitoring of interesting eclipsing systems. Using published and new mid-eclipse times obtained between 2004 and 2011 we constructed the observed-minus-calculated diagram. The current data present 21 years of period modulation with a semi-amplitude of 2.5 min. The eclipse timings show significant deviations from the best sinusoidal fit, which indicates that this ephemeris is not a complete description of the data. The fractional period change is roughly ΔP/P = 3 × 10-6.

GJ 3236 - radial velocity determination

NASA Astrophysics Data System (ADS)

Kára, J.; Wolf, M.; Zharikov, S.

2018-04-01

We present a new study of low-mass red-dwarf eclipsing binary GJ 3236 using spectroscopic data obtained by the 2.12-m telescope at the San Pedro Mártir Observatory. We resolved radial velocities of both components of the binary and improved determination of the physical parameters of the binary.

The Araucaria project. The distance to the small Magellanic Cloud from late-type eclipsing binaries

DOE Office of Scientific and Technical Information (OSTI.GOV)

Graczyk, Dariusz; Pietrzyński, Grzegorz; Gieren, Wolfgang

2014-01-01

We present a distance determination to the Small Magellanic Cloud (SMC) based on an analysis of four detached, long-period, late-type eclipsing binaries discovered by the Optical Gravitational Lensing Experiment (OGLE) survey. The components of the binaries show negligible intrinsic variability. A consistent set of stellar parameters was derived with low statistical and systematic uncertainty. The absolute dimensions of the stars are calculated with a precision of better than 3%. The surface brightness-infrared color relation was used to derive the distance to each binary. The four systems clump around a distance modulus of (m – M) = 18.99 with a dispersionmore » of only 0.05 mag. Combining these results with the distance published by Graczyk et al. for the eclipsing binary OGLE SMC113.3 4007, we obtain a mean distance modulus to the SMC of 18.965 ± 0.025 (stat.) ± 0.048 (syst.) mag. This corresponds to a distance of 62.1 ± 1.9 kpc, where the error includes both uncertainties. Taking into account other recent published determinations of the SMC distance we calculated the distance modulus difference between the SMC and the Large Magellanic Cloud equal to 0.458 ± 0.068 mag. Finally, we advocate μ{sub SMC} = 18.95 ± 0.07 as a new 'canonical' value of the distance modulus to this galaxy.« less

Orbital period changes in RW CrA, DX Vel and V0646 Cen

NASA Astrophysics Data System (ADS)

Volkov, I. M.; Chochol, D.; Grygar, J.; Mašek, M.; Juryšek, J.

2017-06-01

We aim to determine the absolute parameters of the components of southern Algol-type binaries with deep eclipses RW CrA, DX Vel, V0646 Cen and interpret their orbital period changes. The data analysis is based on a high quality Walraven photoelectric photometry, obtained in the 1960-70s, our recent CCD photometry, ASAS (Pojmanski, 2002), and Hipparcos (Perryman et al., 1997) photometry of the objects. Their light curves were analyzed using the PHOEBE program with fixed effective temperatures of the primary components, found from disentangling the Walraven (B-U) and (V-B) colour indices. We found the absolute parameters of the components of all three objects. All reliable observed times of minimum light were used to construct and analyze the Eclipse Time Variation (ETV) diagrams. We interpreted the ETV diagrams of the detached binary RW CrA and the semi-detached binary DX Vel by a LIght-Time Effect (LITE), estimated parameters of their orbits and masses of their third bodies. We suggest a long term variation of the inclination angle of both eclipsing binaries, caused by a non-coplanar orientation of their third body orbits. We interpreted the detected orbital period increase in the semi-detached binary V0646 Cen by a mass transfer from the less to more massive component with the rate M⊙ = 6.08×10-9 M⊙/yr.

Young and Waltzing Binary Stars

NASA Astrophysics Data System (ADS)

2001-10-01

ADONIS Observes Low-mass Eclipsing System in Orion Summary A series of very detailed images of a binary system of two young stars have been combined into a movie . In merely 3 days, the stars swing around each other. As seen from the earth, they pass in front of each other twice during a full revolution, producing eclipses during which their combined brightness diminishes . A careful analysis of the orbital motions has now made it possible to deduce the masses of the two dancing stars . Both turn out to be about as heavy as our Sun. But while the Sun is about 4500 million years old, these two stars are still in their infancy. They are located some 1500 light-years away in the Orion star-forming region and they probably formed just 10 million years ago . This is the first time such an accurate determination of the stellar masses could be achieved for a young binary system of low-mass stars . The new result provides an important piece of information for our current understanding of how young stars evolve. The observations were obtained by a team of astronomers from Italy and ESO [1] using the ADaptive Optics Near Infrared System (ADONIS) on the 3.6-m telescope at the ESO La Silla Observatory. PR Photo 29a/01 : The RXJ 0529.4+0041 system before primary eclipse PR Photo 29b/01 : The RXJ 0529.4+0041 system at mid-primary eclipse PR Photo 29c/01 : The RXJ 0529.4+0041 system after primary eclipse PR Photo 29d/01 : The RXJ 0529.4+0041 system before secondary eclipse PR Photo 29e/01 : The RXJ 0529.4+0041 system at mid-secondary eclipse PR Photo 29f/01 : The RXJ 0529.4+0041 system after secondary eclipse PR Video Clip 06/01 : Video of the RXJ 0529.4+0041 system Binary stars and stellar masses Since some time, astronomers have noted that most stars seem to form in binary or multiple systems. This is quite fortunate, as the study of binary stars is the only way in which it is possible to measure directly one of the most fundamental quantities of a star, its mass. The mass of a star determines its fate . Massive stars (with masses more than 50 times that of the Sun) lead a glorious, but short life. They are hot and very luminous and exhaust their energy supply in just a few million years. At the other end of the scale, low-mass stars like the Sun are more economical with their resources. Being cooler and dimmer, they are able to shine for billions of years [2]. But although the mass determines the fate of a star, it is not a trivial matter to measure this crucial parameter. In fact, it can only be determined directly if the star happens to be gravitationally bound to another star in a binary stellar system. Observations of the orbital motions of the two stars as they circle each other allows to "weigh" them, and also provide other important information, e.g. about their sizes and temperatures. Orbital motions The understanding of orbital motions has a long history in astronomy. The basic laws of Johannes Kepler (1571-1630) are still used to calculate the masses of orbiting objects, in the solar system as well as in binary stellar systems. However, while the observations of the motion of the nine planets and moons have allowed us to measure quite accurately the masses of objects in our vicinity, the information needed to "weigh" the binary stellar systems is not that easy to obtain. As a result, the mass estimates of the stars in binary systems are often rather uncertain. A main problem is that the individual stars in many binary systems can not be visually separated, even in the best telescopes. The information about the orbit may then come from the motions of the stars, if these are revealed by spectroscopic observations of the combined light (such systems are referred to as "spectroscopic binaries"). If absorption lines from both components are present in the spectrum, the measured wavelength of these double lines will shift periodically back and forth. This is the well-known Doppler effect and it directly reflects the changing velocities of the stars, as they move along their orbits and periodically approach and recede from the observer. Such spectroscopic observations therefore allow to measure the orbital velocities of the stars. It is exactly the same technique that is used to study and weigh extra-solar planets orbiting other stars [3]. However, this method has an important limitation. From the spectroscopical observations alone, it is only possible to deduce limits on the masses, as the inclination of orbits to the line-of-sight is usually unknown. The masses derived in this way (for stars as well as for exoplanets) are therefore only lower limits on the actual masses. Eclipsing Binaries However, fortunate observational circumstances sometimes allow to obtain all information about the stellar orbits. If a binary system is viewed (almost exactly) edge-on, the stars may pass in front of each other from time to time. Astronomers refer to this phenomenon as an "eclipse" and speak about an "eclipsing binary". The effect is similar to a "solar" eclipse as seen on the Earth, whenever the Moon passes in front of the Sun. Like the Moon blocks the sunlight, less light is received from the eclipsed star and thus the combined light from the binary system decreases during the eclipse. The way this happens (astronomers speak about the system's "lightcurve") then provides the additional information about the inclination of the orbit that is needed to determine exactly the stellar masses in a "spectroscopic" binary system. Very accurate values for the stellar diameters and the surface temperatures of the two stars can also be deduced. In short, when a full set of observations is available, it is possible to give a comprehensive description of an eclipsing binary system and its components. Eclipsing, spectroscopic binaries thus represent true cornerstones for the determination of stellar masses , and as such they are fundamental for our understanding of stellar evolution . Rather few such systems are known, but they can also be used to check ("calibrate") other, indirect methods to derive stellar parameters. It is on this background that the first discovery of an eclipsing binary system with two young, solar-like stars is of great interest. The Orion Binary Young stars are not so easy to find. One way is to look for their high-energy emission from a hot corona, created by their enhanced magnetic activity. The object RXJ 0529.4+0041 was first discovered in this way by the X-ray satellite ROSAT. Subsequent optical spectroscopy showed this object to be a young, low-mass spectroscopic binary system. And when a team of astronomers [1] used a 91-cm telescope at the Serra La Nave observing station on the slope of the Etna volcano (Sicily) to monitor the light curve, they also discovered that this system undergoes eclipses. All data confirm that RXJ 0529.4+0041 is located in the Orion Nebula at a distance of about 1500 light-years. This is one of the nearest star-forming regions and almost all stars in this area are quite young. Spectroscopic observations soon confirmed that the binary system was no exception. In particular, fairly strong absorption lines of the fragile element Lithium [4] were detected in both of the binary stars. As Lithium is known to be rapidly destroyed in stars, the finding of a relatively high content of this element implies that the stars must indeed be young. They were probably formed no more than 10 million years ago, i.e., in astronomical terms, they are "infant" stars . High-resolution spectroscopic observations, mostly with the CORALIE spectrometer on the Swiss 1.2-m Leonard Euler telescope at the ESO La Silla Observatory , were used to determine the radial velocities of the stars. From these, a first determination of the orbital and stellar parameters was possible. The orbital period turned out to be short. The two stars swing around each other in just 3 days. This also means they must be very close to each other (but still entirely detached from each other) - the detailed analysis showed that the distance between the two components is only 12 solar radii, or a little more than 8 million kilometres. If you would image yourself standing on the surface of the smaller star, the disk of the companion star would extend some 15° in the sky. This is 30 times larger than our view of the Sun! ADONIS observations The short orbital period and the even shorter duration of the eclipses, only 6 hours, posed a real challenge for the observers. They decided to obtain further high-angular resolution observations with the ADaptive Optics Near Infrared System (ADONIS) on the 3.6-m telescope at the ESO La Silla Observatory. Most fortunately, early ADONIS images demonstrated that this binary stellar system has a third companion, sufficiently far away from the two others to be seen as a separate star by ADONIS. This unexpected bonus made it possible to monitor the light changes of the binary system in great detail, by using the third companion as a convenient "reference" star. In December 2000 and January 2001, detailed ADONIS images of the RXJ 0529.4+0041 system were obtained in three near-infrared filters (the J-, H- and K-bands). ADONIS is equipped with the SHARP II camera and eliminates the adverse image-smearing effects of the atmospheric turbulence in real-time by means of a computer-controlled flexible mirror. As expected, the new, extremely sharp images of RXJ 0529.4+0041 greatly improved the achievable photometric precision. In particular, as the image of the third component was perfectly separated from the others, it did not "contaminate" the derived light curve of the eclipsing binary. The movie Primary eclipse Secondary eclipse ESO PR Photo 29a/01 ESO PR Photo 29a/01 [Preview - JPEG: 375 x 400 pix - 87k] [Normal - JPEG: 750 x 800 pix - 240k] ESO PR Photo 29d/01 ESO PR Photo 29d/01 [Preview - JPEG: 375 x 400 pix - 112k] [Normal - JPEG: 750 x 800 pix - 272k] ESO PR Photo 29b/01 ESO PR Photo 29b/01 [Preview - JPEG: 375 x 400 pix - 90k] [Normal - JPEG: 750 x 800 pix - 240k] ESO PR Photo 29e/01 ESO PR Photo 29e/01 [Preview - JPEG: 375 x 400 pix - 112k] [Normal - JPEG: 750 x 800 pix - 280k] ESO PR Photo 29c/01 ESO PR Photo 29c/01 [Preview - JPEG: 375 x 400 pix - 94k] [Normal - JPEG: 750 x 800 pix - 256k] ESO PR Photo 29f/01 ESO PR Photo 29f/01 [Preview - JPEG: 375 x 400 pix - 112k] [Normal - JPEG: 750 x 800 pix - 280k] Caption : Six individual frames from the ADONIS movie of the RXJ 0529.4+0041 eclipsing, binary stellar system, corresponding to the time around the "primary" and "secondary" eclipses, respectively. For a detailed explanation, read the text. ESO PR Video Clip 06/01 [512 x 448 pix MPEG] ESO PR Video Clip 06/01 (150 frames/00:06 min) [MPEG Video; 512 x 448 pix; 871 k] ESO Video Clip 06/01 shows the ADONIS images of the RXJ 0529.4+0041 eclipsing, binary stellar system, as recorded in three near-infrared filters (J, H, and K; to the left), with the observed light-curves (top) and a graphical representation of the system during a full orbit, as it would look like to a nearby observer. More details in the text The ADONIS images have been combined into an instructive movie ( PR Video Clip 06/01 ). The left-hand panel shows the eclipsing binary system (it is the upper right and brighter of the two objects; the light from the two stars merge into a single point of light) and the well visible third component (lower left), as they were recorded by ADONIS in the three different filter bands. As the two stars in the binary system move around each other in their orbits, eclipses occur and the brightness of the binary system clearly changes - it may help to play the movie several times to see this more clearly. For reference, the Universal Time (UT) and the orbital phase (increasing from 0 to 1 during a full revolution) are continuously displayed in the movie. The right-hand panel shows a build-up of the observed light curves for the binary system. It represents the brightness difference between binary system and the third object that shines with constant light. Both the primary, deeper and the secondary, less deep eclipses are well visible. The primary eclipse was observed on December 8, 2000 and is here displayed at phase zero. During this minimum, the brightness of the binary system decreases by about 45% (0.4 magnitudes). The primary eclipse takes place when the smaller component blocks the light from the brighter and hotter star. The orbital motions of the two stars are illustrated by a computer-generated, animated sequence. The secondary eclipse (at phase 0.5) dims the light from the system less; it occurs when the larger and brighter star almost completely (about 90%) hides its smaller companion. The second minimum was recorded on January 12, 2001. None of the eclipses is therefore "total". The stellar parameters A detailed analysis of these high-precision light curves allowed the astronomers to determine the orbits and hence, to perform an extremely accurate measurement of the fundamental stellar parameters for the two young stars of RXJ 0529.4+0041 . The star that is eclipsed during the primary eclipse (the "primary") is the more massive and also the hotter and brighter of the two stars. Its mass is 1.3 times that of our Sun, i.e., about 2.6 10 30 kg [2]. Its diameter is nearly 1.6 times larger than that of our Sun (i.e., about 2.2 million km) and the surface temperature is found to be a little more than 5000 °C, or a few hundred degrees cooler than the Sun. The "secondary" star is slightly lighter than our Sun. Its weight is about 90% of that of the Sun (1.8 10 30 kg) and the diameter is 20% larger (about 1.7 million km), while the surface temperature is 4000 degrees. In fact, these two stars are still so young that most of their energy comes from the contraction process - the first phase during which they are formed from an interstellar cloud by this process is not yet over and they are still getting smaller. It is by this process that collapsing stars heat up enough to start nuclear burning. When infant stars in RXJ 0529.4+0041 eventually reach middle-age, their sizes will most likely also be quite similar to that of the Sun. The significance of RXJ 0529.4+0041 Few systems are known for which such precise determinations of the stellar parameters have ever been possible - and this binary system represents the first case where both the components are such young stars . A detailed comparison of the derived stellar parameters with current models for the evolution of young stars shows fairly good agreement for the primary component. However, there are certain discrepancies in the case of the secondary component, showing that the current models for the early stages of lower-mass stars must still be refined. More information Part of the results described in this press release are described in more detail in a scientific article ( "RXJ 0529.4+0041: a low-mass pre-main sequence eclipsing-spectroscopic binary" by E. Covino et al.) that has been published in the European research journal Astronomy & Astrophysics (Vol. 361, p. 49). Notes [1] The team consists of Elvira Covino (Principal Investigator), Juan M. Alcalá , Rosita Paladino (all Osservatorio Astronomico di Capodimonte, Napoli, Italy), Antonio Frasca , Santo Catalano , Ettore Marilli (all Osservatorio Astrofisico di Catania, Italy) and Michael Sterzik (ESO-Chile). [2] One solar mass corresponds to 1.99 10 30 kg, or about 330,000 times the mass of the Earth. The Sun is about 4500 million years old and its total lifetime is of the order of 12-13,000 million years. It is an interesting thought that if the Sun would have been somewhat heavier, its total lifetime might have been too short for living organisms to develop on the Earth. In fact, the biological evolution that ultimately lead to the emergence of human beings apparently lasted about 4 billion years; this corresponds to the total lifetime of a star that is only about 20 % heavier than the Sun. Note also the current ESO-ESA CERN educational programme on "Life in the Universe". [3] In the case of exoplanets, the planet itself is not visible, but the spectral lines from the star are seen to wobble due to the gravitational influence of the planet, cf. ESO PR 07/01. [4] Several ESO Press Releases concern observations of the element Lithium in stars, e.g., PR 03/99 (in a giant star), PR 08/00 (in a metal-poor star) and PR 10/01 (from a "swallowed" exoplanet).

Light curve variations of the eclipsing binary V367 Cygni

NASA Astrophysics Data System (ADS)

Akan, M. C.

1987-07-01

The long-period eclipsing binary star V367 Cygni has been observed photoelectrically in two colours, B and V, in 1984, 1985, and 1986. These new light curves of the system have been discussed and compared for the light-variability with the earlier ones presented by Heiser (1962). Using some of the previously published photoelectric light curves and the present ones, several primary minima times have been derived to calculate the light elements. Any attempt to obtain a photometric solution of the binary is complicated by the peculiar nature of the light curve caused by the presence of the circumstellar matter in the system. Despite this difficulty, however, some approaches are being carried out to solve the light curves which are briefly discussed.

WIYN OPEN CLUSTER STUDY. XLVIII. THE HARD-BINARY POPULATION OF NGC 188

DOE Office of Scientific and Technical Information (OSTI.GOV)

Geller, Aaron M.; Mathieu, Robert D., E-mail: a-geller@northwestern.edu, E-mail: mathieu@astro.wisc.edu

2012-08-15

We present an in-depth study of the hard-binary population of the old (7 Gyr) open cluster NGC 188. Utilizing 85 spectroscopic binary orbits out of a complete sample of 129 detected binary members, we study the cluster binary frequency and the distributions of binary orbital elements among the main-sequence (MS), giant, and blue straggler (BS) populations. The results are derived from our ongoing radial velocity survey of the cluster, which spans in magnitude from the brightest stars in the cluster to V = 16.5 (about 1.1-0.9 M{sub Sun} ), and extends to a projected radius of 17 pc ({approx}13 coremore » radii). Our detectable binaries have periods ranging from a few days to of order 10{sup 4} days, and thus are hard binaries that dynamically power the cluster. The MS solar-type hard binaries in NGC 188 are nearly indistinguishable from similar binaries in the Galactic field. We observe a global solar-type MS hard-binary frequency in NGC 188 of 23% {+-} 2%, which when corrected for incompleteness results in a frequency of 29% {+-} 3% for binaries with periods less than 10{sup 4} days. For MS hard binaries in the cluster, we observe a log-period distribution that rises toward our detection limit, a roughly Gaussian eccentricity distribution centered on e = 0.35 (for binaries with periods longer than the circularization period), and a secondary-mass distribution that rises toward lower-mass companions. Importantly, the NGC 188 BS binaries show significantly different characteristics than the solar-type MS binaries in NGC 188. We observe a BS hard-binary frequency of 76% {+-} 19%, three times that of the MS. The excess of this binary frequency over the normal MS binary frequency is valid at the >99% confidence level. Furthermore, the BS binary eccentricity-log-period distribution is distinct from that of the MS at the 99% confidence level, with the majority of the BS binaries having periods of order 1000 days and lower eccentricities. The secondary-mass distribution for these long-period BS binaries is narrow and peaked with a mean value of about 0.5 M{sub Sun }. Predictions for mass-transfer products are most closely consistent with the binary properties of these NGC 188 BSs, which comprise two-thirds of the BS population. Additionally, we compare the NGC 188 binaries to those evolved within the sophisticated Hurley et al. (2005) N-body open cluster simulation. The MS hard-binary population predicted by the simulation is significantly different from the MS hard-binary population observed in NGC 188, in frequency and distributions of period and eccentricity. Many of these differences result from the adopted initial binary population, while others reflect on the physics used in the simulation (e.g., tidal circularization). Additional simulations with initial conditions that are better motivated by observations are necessary to properly investigate the dynamical evolution of a rich binary population in open clusters like NGC 188.« less

On Orbital Elements of Extrasolar Planetary Candidates and Spectroscopic Binaries

NASA Technical Reports Server (NTRS)

Stepinski, T. F.; Black, D. C.

2001-01-01

We estimate probability densities of orbital elements, periods, and eccentricities, for the population of extrasolar planetary candidates (EPC) and, separately, for the population of spectroscopic binaries (SB) with solar-type primaries. We construct empirical cumulative distribution functions (CDFs) in order to infer probability distribution functions (PDFs) for orbital periods and eccentricities. We also derive a joint probability density for period-eccentricity pairs in each population. Comparison of respective distributions reveals that in all cases EPC and SB populations are, in the context of orbital elements, indistinguishable from each other to a high degree of statistical significance. Probability densities of orbital periods in both populations have P(exp -1) functional form, whereas the PDFs of eccentricities can he best characterized as a Gaussian with a mean of about 0.35 and standard deviation of about 0.2 turning into a flat distribution at small values of eccentricity. These remarkable similarities between EPC and SB must be taken into account by theories aimed at explaining the origin of extrasolar planetary candidates, and constitute an important clue us to their ultimate nature.

Spectral irradiance curve calculations for any type of solar eclipse

NASA Technical Reports Server (NTRS)

Deepak, A.; Merrill, J. E.

1974-01-01

A simple procedure is described for calculating the eclipse function (EF), alpha, and hence the spectral irradiance curve (SIC), (1-alpha), for any type of solar eclipse: namely, the occultation (partial/total) eclipse and the transit (partial/annular) eclipse. The SIC (or the EF) gives the variation of the amount (or the loss) of solar radiation of a given wavelength reaching a distant observer for various positions of the moon across the sun. The scheme is based on the theory of light curves of eclipsing binaries, the results of which are tabulated in Merrill's Tables, and is valid for all wavelengths for which the solar limb-darkening obeys the cosine law: J = sub c (1 - X + X cost gamma). As an example of computing the SIC for an occultation eclipse which may be total, the calculations for the March 7, 1970, eclipse are described in detail.

Fundamental frequencies and resonances from eccentric and precessing binary black hole inspirals

NASA Astrophysics Data System (ADS)

Lewis, Adam G. M.; Zimmerman, Aaron; Pfeiffer, Harald P.

2017-06-01

Binary black holes which are both eccentric and undergo precession remain unexplored in numerical simulations. We present simulations of such systems which cover about 50 orbits at comparatively high mass ratios 5 and 7. The configurations correspond to the generic motion of a nonspinning body in a Kerr spacetime, and are chosen to study the transition from finite mass-ratio inspirals to point particle motion in Kerr. We develop techniques to extract analogs of the three fundamental frequencies of Kerr geodesics, compare our frequencies to those of Kerr, and show that the differences are consistent with self-force corrections entering at first order in mass ratio. This analysis also locates orbital resonances where the ratios of our frequencies take rational values. At the considered mass ratios, the binaries pass through resonances in one to two resonant cycles, and we find no discernible effects on the orbital evolution. We also compute the decay of eccentricity during the inspiral and find good agreement with the leading order post-Newtonian prediction.

VX Her: Eclipsing Binary System or Single Variable Star

NASA Astrophysics Data System (ADS)

Perry, Kathleen; Castelaz, Michael; Henson, Gary; Boghozian, Andrew

2015-01-01

VX Her is a pulsating variable star with a period of .4556504 days. It is believed to be part of an eclipsing binary system (Fitch et al. 1966). This hypothesis originated from Fitch seeing VX Her's minimum point on its light curve reaching a 0.7 magnitude fainter than normal and remaining that way for nearly two hours. If VX Her were indeed a binary system, I would expect to see similar results with a fainter minimum and a broader, more horizontal dip. Having reduced and analyzed images from the Southeastern Association for Research in Astronomy Observatory in Chile and Kitt Peak, as well as images from a 0.15m reflector at East Tennessee State University, I found that VX Her has the standard light curve of the prototype variable star, RR Lyrae. Using photometry, I found no differing features in its light curve to suggest that it is indeed a binary system. However, more observations are needed in case VX Her is a wide binary.

Observations of hot stars and eclipsing binaries with FRESIP

NASA Technical Reports Server (NTRS)

Gies, Douglas R.

1994-01-01

The FRESIP project offers an unprecedented opportunity to study pulsations in hot stars (which vary on time scales of a day) over a several year period. The photometric data will determine what frequencies are present, how or if the amplitudes change with time, and whether there is a connection between pulsation and mass loss episodes. It would initiate a new field of asteroseismology studies of hot star interiors. A search should be made for selected hot stars for inclusion in the list of project targets. Many of the primary solar mass targets will be eclipsing binaries, and I present estimates of their frequency and typical light curves. The photometric data combined with follow up spectroscopy and interferometric observations will provide fundamental data on these stars. The data will provide definitive information on the mass ratio distribution of solar-mass binaries (including the incidence of brown dwarf companions) and on the incidence of planets in binary systems.

What Makes Red Giants Tick? Linking Tidal Forces, Activity, and Solar-Like Oscillations via Eclipsing Binaries

NASA Astrophysics Data System (ADS)

Rawls, Meredith L.; Gaulme, Patrick; McKeever, Jean; Jackiewicz, Jason

2016-01-01

Thanks to advances in asteroseismology, red giants have become astrophysical laboratories for studying stellar evolution and probing the Milky Way. However, not all red giants show solar-like oscillations. It has been proposed that stronger tidal interactions from short-period binaries and increased magnetic activity on spotty giants are linked to absent or damped solar-like oscillations, yet each star tells a nuanced story. In this work, we characterize a subset of red giants in eclipsing binaries observed by Kepler. The binaries exhibit a range of orbital periods, solar-like oscillation behavior, and stellar activity. We use orbital solutions together with a suite of modeling tools to combine photometry and spectroscopy in a detailed analysis of tidal synchronization timescales, star spot activity, and stellar evolution histories. These red giants offer an unprecedented opportunity to test stellar physics and are important benchmarks for ensemble asteroseismology.

The infrared counterpart of the eclipsing X-ray binary HO253 + 193

NASA Technical Reports Server (NTRS)

Zuckerman, B.; Becklin, E. E.; Mclean, I. S.; Patterson, Joseph

1992-01-01

We report the identification of the infrared counterpart of the pulsating X-ray source HO253 + 193. It is a highly reddened star varying in K light with a period near 3 hr, but an apparent even-odd effect in the light curve implies that the true period is 6.06 hr. Together with the recent report of X-ray eclipses at the latter period, this establishes the close binary nature of the source. Infrared minimum occurs at X-ray minimum, certifying that the infrared variability arises from the tidal distortion of the lobe-filling secondary. The absence of a point source at radio wavelengths, plus the distance derived from the infrared data, suggests that the binary system is accidentally located behind the dense core of the molecular cloud Lynds 1457. The eclipses and pulsations in the X-ray light curve, coupled with the hard X-ray spectrum and low luminosity, demonstrate that HO253 + 193 contains an accreting magnetic white dwarf, and hence belongs to the 'DQ Herculis' class of cataclysmic variables.

The Chandra Delta Ori Large Project: Occultation Measurements of the Shocked Gas tn the Nearest Eclipsing O-Star Binary

NASA Technical Reports Server (NTRS)

Corcoran, Michael F.; Nichols, Joy; Naze, Yael; Rauw, Gregor; Pollock, Andrew; Moffat, Anthony; Richardson, Noel; Evans, Nancy; Hamaguchi, Kenji; Oskinova, Lida;

Timing of Five PALFA-discovered Millisecond Pulsars

NASA Astrophysics Data System (ADS)

Stovall, K.; Allen, B.; Bogdanov, S.; Brazier, A.; Camilo, F.; Cardoso, F.; Chatterjee, S.; Cordes, J. M.; Crawford, F.; Deneva, J. S.; Ferdman, R.; Freire, P. C. C.; Hessels, J. W. T.; Jenet, F.; Kaplan, D. L.; Karako-Argaman, C.; Kaspi, V. M.; Knispel, B.; Kotulla, R.; Lazarus, P.; Lee, K. J.; van Leeuwen, J.; Lynch, R.; Lyne, A. G.; Madsen, E.; McLaughlin, M. A.; Patel, C.; Ransom, S. M.; Scholz, P.; Siemens, X.; Stairs, I. H.; Stappers, B. W.; Swiggum, J.; Zhu, W. W.; Venkataraman, A.

2016-12-01

We report the discovery and timing results for five millisecond pulsars (MSPs) from the Arecibo PALFA survey: PSRs J1906+0055, J1914+0659, J1933+1726, J1938+2516, and J1957+2516. Timing observations of the five pulsars were conducted with the Arecibo and Lovell telescopes for time spans ranging from 1.5 to 3.3 years. All of the MSPs except one (PSR J1914+0659) are in binary systems with low eccentricities. PSR J1957+2516 is likely a redback pulsar, with a ˜ 0.1 {M}⊙ companion and possible eclipses that last ˜10% of the orbit. The position of PSR J1957+2516 is also coincident with a near-infrared source. All five MSPs are distant (\\gt 3.1 kpc) as determined from their dispersion measures, and none of them show evidence of γ-ray pulsations in a fold of Fermi Gamma-Ray Space Telescope data. These five MSPs bring the total number of MSPs discovered by the PALFA survey to 26 and further demonstrate the power of this survey in finding distant, highly dispersed MSPs deep in the Galactic plane.

The Bulgarian Contribution to the Study of variable stars on observational data from the Kepler mission

NASA Astrophysics Data System (ADS)

Kjurkchieva, D. P.; Dimitrov, D. P.; Radeva, V. S.; Vasileva, D. L.; Atanasova, T. V.; Stateva, I. V.; Petrov, N. I.; Iliev, I. Kh.

2018-02-01

This review paper presents the results of investigations of variable stars obtained by Bulgarian astronomers based on observations of Kepler mission. The main contributions are: determination of orbits and global parameters of more than 100 binary stars; creation of the largest catalog of eccentric stars; identification of sixty new binaries with eccentricity over 0.5; discovery of 19 heartbeat stars; detailed investigation of the spot and flare activity of several binary stars; asteroseismic study of three pulsating stars; detection of deep transits of WD 1145+017 due to its disentangling planet system. The paper illustrates not only scientific significance but also educational and social impact of the work on these tasks.

Searching for Extrasolar Trojan Planets: A Status Report

NASA Astrophysics Data System (ADS)

Caton, D. B.; Davis, S. A.; Kluttz, K. A.; Stamilio, R. J.; Wohlman, K. D.

2001-05-01

We are exploring the light curves of eclipsing binaries for the photometric signature of planets that may exist at the L4 and L5 Lagrange points of the stellar system. While no binaries are known to exist that strictly satisfy the stellar mass ratio constraint for the restricted three-body problem, the general solution would allow a planet formed at the L-point to remain there if there are no major perturbing bodies such as an additional planet. We have coined such objects "Trojan planets." The advantage of this approach is that the phases of the planetary eclipses are known. We picked systems with deep primary eclipses, to maximize the amount of system light eclipsed by the planet when in front of the hotter star. We also scanned the Finding List for Observers of Interactive Binary Stars, for G dwarf systems, but found only a few that were high inclination and detached. The target list includes QY Aql, YZ Aql, V442 Cas, SS Cet, S Cnc, VW Cyg, WW Cyg, RR Dra, RX Gem, RY Gem, VW Hya, Y Leo, TV Mon, BN Sct, UW Vir, AC UMa, and GSC 1657. We have concentrated on V442 Cas and YZ Aql, based on initial results that show anomalies in the light curves near the phases where a Trojan planet eclipse is expected. New work is being done on brighter systems by using a "spot filter," similar to that developed by Castellano (PASP 112, 821-6),2000), to allow longer exposures that provide brighter comparison stars. We will report on the observations made to date on several systems. We gratefully acknowledge the support of the National Science Foundation, through grants AST-9731062 and AST-0089248. We also appreciate the support of the Fund for Astrophysical Research. Gregory Shelton and Brenda Corbin, at the U.S. naval Observatory Library, have been indispensable in providing references for these binary systems. This research has made use of the Simbad database, operated at CDS, Strasbourg, France

Simulating the X-ray luminosity of Be X-ray binaries: the case for black holes versus neutron stars

NASA Astrophysics Data System (ADS)

Brown, R. O.; Ho, W. C. G.; Coe, M. J.; Okazaki, A. T.

2018-04-01

There are over 100 Be stars that are known to have neutron star companions but only one such system with a black hole. Previous theoretical work suggests this is not due to their formation but due to differences in X-ray luminosity. It has also been proposed that the truncation of the Be star's circumstellar disc is dependent on the mass of the compact object. Hence, Be star discs in black hole binaries are smaller. Since accretion onto the compact object from the Be star's disc is what powers the X-ray luminosity, a smaller disc in black hole systems leads to a lower luminosity. In this paper, simulations are performed with a range of eccentricities and compact object mass. The disc's size and density are shown to be dependent on both quantities. Mass capture and, in turn, X-ray luminosity are heavily dependent on the size and density of the disc. Be/black hole binaries are expected to be up to ˜10 times fainter than Be/neutron star binaries when both systems have the same eccentricity and can be 100 times fainter when comparing systems with different eccentricity.

GSC 4232.2850, a new eclipsing binary with elliptical orbit

NASA Astrophysics Data System (ADS)

Goranskij, V.; Shugarov, S.; Kroll, P.; Golovin, A.

2005-04-01

GSC 4232.2830 (20h 01m 28s.407, +61? 10' 17".18, 2000.0, v=12m.1) was suspected to be an eclipsing binary by VPG in the routine overview of photographical plates taken with 40-cm astrograph of SAI Crimean station. To define orbital elements of the binary, we searched for observations in Sonneberg Observatory plate collection, NSVS database (Wozniak et al., 2004), and carried out visual monitoring with a small telescope equipped with an electronic image tube, an analogue of a night vision device. Later, when we had found a preliminary solution, we carried out accurate CCD photometry to improve the orbital elements. We should note, that the depths of eclipses in the NSVS database do not exceed 0m.2, what contradicts to other observations. We suppose that NSVS measurements concern to integral light of two stars, a variable star, and a nearby brighter star, GSC 4232.2395, due to low resolution of this survey, 72". Using all the available observations we found the single orbital solution with an elliptical orbit and the period of 11,6 day. The center of the secondary minimum occurs at the orbital phase 0.69835 or 8.1 day after the primary minimum. The improved ephemeris derived using accurate CCD observations is following: HJD Min I = 2453278,3185(2) + 11.628188 (5) x E. O-C analysis does not show orbital period variations during the time interval of observations, or any evidence of apsidal motion. The observations show that both eclipses have about equal depth 0m.60, but essentially different duration, 0p.028 (7 h.8) for Min I, and 0 p.0175 (4 h.9) for Min II. The eclipses are partial. CCD photometry gives mean colors U-B = -0 m.06, B-V = 0 m.57, and V-R = 0 m.50 without notable color variations in the eclipse phases. Old Sonneberg photographic observations indicate that the eclipses were shallower in the middle of the past century than in the present time! Such contradictions may suggest that the depth of eclipses varied, as in the well-known system SSLac (Mossakovskaja, 1993; Milone et al, 2000; Torres and Stefanic, 2001). The eclipse depth variations should be verified with more precise observations taken during the longer time interval.

High-energy emission from the eclipsing millisecond pulsar PSR 1957+20

NASA Technical Reports Server (NTRS)

Arons, Jonathan; Tavani, Marco

1993-01-01

The properties of the high-energy emission expected from the eclipsing millisecond pulsar system PSR 1957+20 are investigated. Emission is considered by both the relativistic shock produced by the pulsar wind in the nebula surrounding the binary and by the shock constraining the mass outflow from the companion star of PSR 1957+20. On the basis of the results of microscopic plasma physical models of relativistic shocks it is suggested that the high-energy radiation is produced in the range from X-rays to MeV gamma rays in the binary and in the range from 0.01 eV to about 40 keV in the nebula. Doppler boost of the emission in the radiating wind suggests the flux should vary on the orbital time scale, with the largest flux observed roughly coincident with the pulsar's radio eclipse.

Modeling Radial Velocities and Eclipse Photometry of the Kepler Target KIC 4054905: an Oscillating Red Giant in an Eclipsing Binary

NASA Astrophysics Data System (ADS)

Benbakoura, M.; Gaulme, P.; McKeever, J.; Beck, P. G.; Jackiewicz, J.; García, R. A.

2017-12-01

Asteroseismology is a powerful tool to measure the fundamental properties of stars and probe their interiors. This is particularly efficient for red giants because their modes are well detectable and give information on their deep layers. However, the seismic relations used to infer the mass and radius of a star have been calibrated on the Sun. Therefore, it is crucial to assess their accuracy for red giants which are not perfectly homologous to it. We study eclipsing binaries with a giant component to test their validity. We identified 16 systems for which we intend to compare the dynamical masses and radii obtained by combined photometry and spectroscopy to the values obtained from asteroseismology. In the present work, we illustrate our approach on a system from our sample.

IUE observations of the atmospheric eclipsing binary system Zeta Aurigae

NASA Technical Reports Server (NTRS)

Champman, R. D.

1980-01-01

IUE observations of the eclipsing binary system Zeta Aurigae made prior to and during the eclipse of the relatively small B8 V star by the cool supergiant star (spectral type K2 II) are reported. Spectral lines produced by the absorption of B star radiation in the atmosphere of the K star during eclipse can be used as a probe of the extended K star atmosphere, due to the negligible cool star continuum in the 1200-3200 A region. Spectra taken prior to eclipse are found to be similar to those of the single B8 V star 64 Ori, with the exception of very strong multi-component absorption lines of Si II, Si IV, C IV and the Mg resonance doublet with strong P Cygni profiles, indicating a double shell. Absorption lines including those corresponding to Al II, Al III, Cr II, Mn II, Fe II, Ni II and Ca II are observed to increase in strength and number as the eclipse progresses, with high-ionization-potential lines formed far from the K star, possibly in a shock wave, and low-ionization potential lines, formed in cool plasma, probably a cool wind, nearer to the K star. Finally, an emission-line spectra with lines corresponding to those previously observed in absorption is noted at the time the B-star continuum had disappeared.

Terrestrial Planet Formation in Binary Star Systems

NASA Technical Reports Server (NTRS)

Lissauer, J. J.; Quintana, E. V.; Adams, F. C.; Chambers, J. E.

2006-01-01

Most stars reside in binary/multiple star systems; however, previous models of planet formation have studied growth of bodies orbiting an isolated single star. Disk material has been observed around one or both components of various young close binary star systems. If planets form at the right places within such disks, they can remain dynamically stable for very long times. We have simulated the late stages of growth of terrestrial planets in both circumbinary disks around 'close' binary star systems with stellar separations ($a_B$) in the range 0.05 AU $\\le a_B \\le$ 0.4 AU and binary eccentricities in the range $0 \\le e \\le 0.8$ and circumstellar disks around individual stars with binary separations of tens of AU. The initial disk of planetary embryos is the same as that used for simulating the late stages of terrestrial planet growth within our Solar System and around individual stars in the Alpha Centauri system (Quintana et al. 2002, A.J., 576, 982); giant planets analogous to Jupiter and Saturn are included if their orbits are stable. The planetary systems formed around close binaries with stellar apastron distances less than or equal to 0.2 AU with small stellar eccentricities are very similar to those formed in the Sun-Jupiter-Saturn, whereas planetary systems formed around binaries with larger maximum separations tend to be sparser, with fewer planets, especially interior to 1 AU. Likewise, when the binary periastron exceeds 10 AU, terrestrial planets can form over essentially the entire range of orbits allowed for single stars with Jupiter-like planets, although fewer terrestrial planets tend to form within high eccentricity binary systems. As the binary periastron decreases, the radial extent of the terrestrial planet systems is reduced accordingly. When the periastron is 5 AU, the formation of Earth-like planets near 1 AU is compromised.

Analysis of Secondary Eclipse Observations of Exoplanet WASP-34b

NASA Astrophysics Data System (ADS)

Challener, Ryan; Harrington, Joseph; Garland, Justin; Cubillos, Patricio; Blecic, Jasmina; Smalley, Barry

2014-11-01

WASP-34b is a short-period exoplanet with a mass of 0.59 +/- 0.01 Jupiter masses orbiting a sun-like star with a period of 4.3177 days and an eccentricity of 0.038 +/- 0.012 (Smalley, 2010). We observed WASP-34b using the 3.6 and 4.5 micron channels of the Infrared Array Camera aboard the Spitzer Space Telescope in 2010 (Program 60003). We present eclipse-depth measurements, estimates of infrared brightness temperatures, and refine the orbit using our secondary eclipse measurements. 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 NNX12AI69G and NASA Astrophysics Data Analysis Program grant NNX13AF38G. JB holds a NASA Earth and Space Science Fellowship.

An eclipsing-binary distance to the Large Magellanic Cloud accurate to two per cent.

PubMed

Pietrzyński, G; Graczyk, D; Gieren, W; Thompson, I B; Pilecki, B; Udalski, A; Soszyński, I; Kozłowski, S; Konorski, P; Suchomska, K; Bono, G; Moroni, P G Prada; Villanova, S; Nardetto, N; Bresolin, F; Kudritzki, R P; Storm, J; Gallenne, A; Smolec, R; Minniti, D; Kubiak, M; Szymański, M K; Poleski, R; Wyrzykowski, L; Ulaczyk, K; Pietrukowicz, P; Górski, M; Karczmarek, P

2013-03-07

In the era of precision cosmology, it is essential to determine the Hubble constant to an accuracy of three per cent or better. At present, its uncertainty is dominated by the uncertainty in the distance to the Large Magellanic Cloud (LMC), which, being our second-closest galaxy, serves as the best anchor point for the cosmic distance scale. Observations of eclipsing binaries offer a unique opportunity to measure stellar parameters and distances precisely and accurately. The eclipsing-binary method was previously applied to the LMC, but the accuracy of the distance results was lessened by the need to model the bright, early-type systems used in those studies. Here we report determinations of the distances to eight long-period, late-type eclipsing systems in the LMC, composed of cool, giant stars. For these systems, we can accurately measure both the linear and the angular sizes of their components and avoid the most important problems related to the hot, early-type systems. The LMC distance that we derive from these systems (49.97 ± 0.19 (statistical) ± 1.11 (systematic) kiloparsecs) is accurate to 2.2 per cent and provides a firm base for a 3-per-cent determination of the Hubble constant, with prospects for improvement to 2 per cent in the future.

Photometric Mapping of Two Kepler Eclipsing Binaries: KIC11560447 and KIC8868650

NASA Astrophysics Data System (ADS)

Senavci, Hakan Volkan; Özavci, I.; Isik, E.; Hussain, G. A. J.; O'Neal, D. O.; Yilmaz, M.; Selam, S. O.

2018-04-01

We present the surface maps of two eclipsing binary systems KIC11560447 and KIC8868650, using the Kepler light curves covering approximately 4 years. We use the code DoTS, which is based on maximum entropy method in order to reconstruct the surface maps. We also perform numerical tests of DoTS to check the ability of the code in terms of tracking phase migration of spot clusters. The resulting latitudinally averaged maps of KIC11560447 show that spots drift towards increasing orbital longitudes, while the overall behaviour of spots on KIC8868650 drifts towards decreasing latitudes.

Massive companions of binary systems

NASA Astrophysics Data System (ADS)

Jableka, D.; Zola, S.; Zakrzewski, B.; Kreiner, J. M.; Ogloza, W.

2018-04-01

We examined the O-C diagrams of eclipsing binary systems and selected these exhibiting cyclic shape, either sinusoidal or quasi sinusoidal. Assuming these variations being due to the Light Time Travel effect (LTE), we estimated the parameters of companions with the Monte Carlo method. As a result, we identified nearly two dozen of eclipsing systems that might have companions with a minimum mass larger than that of a neutron star. Their masses fall into the range between 1.7 and 34 solar masses. This sample of triples with high mass companions can be confirmed with the help of observations gathered by Gaia: parallaxes and astrometric measurements.

Classification of close binary systems by Svechnikov

NASA Astrophysics Data System (ADS)

Dryomova, G. N.

The paper presents the historical overview of classification schemes of eclipsing variable stars with the foreground of advantages of the classification scheme by Svechnikov being widely appreciated for Close Binary Systems due to simplicity of classification criteria and brevity.

Evolution of Binary Supermassive Black Holes in Rotating Nuclei

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rasskazov, Alexander; Merritt, David

The interaction of a binary supermassive black hole with stars in a galactic nucleus can result in changes to all the elements of the binary’s orbit, including the angles that define its orientation. If the nucleus is rotating, the orientation changes can be large, causing large changes in the binary’s orbital eccentricity as well. We present a general treatment of this problem based on the Fokker–Planck equation for f , defined as the probability distribution for the binary’s orbital elements. First- and second-order diffusion coefficients are derived for the orbital elements of the binary using numerical scattering experiments, and analyticmore » approximations are presented for some of these coefficients. Solutions of the Fokker–Planck equation are then derived under various assumptions about the initial rotational state of the nucleus and the binary hardening rate. We find that the evolution of the orbital elements can become qualitatively different when we introduce nuclear rotation: (1) the orientation of the binary’s orbit evolves toward alignment with the plane of rotation of the nucleus and (2) binary orbital eccentricity decreases for aligned binaries and increases for counteraligned ones. We find that the diffusive (random-walk) component of a binary’s evolution is small in nuclei with non-negligible rotation, and we derive the time-evolution equations for the semimajor axis, eccentricity, and inclination in that approximation. The aforementioned effects could influence gravitational wave production as well as the relative orientation of host galaxies and radio jets.« less

Binary Black Hole Mergers from Field Triples: Properties, Rates, and the Impact of Stellar Evolution

DOE Office of Scientific and Technical Information (OSTI.GOV)

Antonini, Fabio; Toonen, Silvia; Hamers, Adrian S.

We consider the formation of binary black hole (BH) mergers through the evolution of field massive triple stars. In this scenario, favorable conditions for the inspiral of a BH binary are initiated by its gravitational interaction with a distant companion, rather than by a common-envelope phase invoked in standard binary evolution models. We use a code that follows self-consistently the evolution of massive triple stars, combining the secular triple dynamics (Lidov–Kozai cycles) with stellar evolution. After a BH triple is formed, its dynamical evolution is computed using either the orbit-averaged equations of motion, or a high-precision direct integrator for triplesmore » with weaker hierarchies for which the secular perturbation theory breaks down. Most BH mergers in our models are produced in the latter non-secular dynamical regime. We derive the properties of the merging binaries and compute a BH merger rate in the range (0.3–1.3) Gpc{sup −3} yr{sup −1}, or up to ≈2.5 Gpc{sup −3} yr{sup −1} if the BH orbital planes have initially random orientation. Finally, we show that BH mergers from the triple channel have significantly higher eccentricities than those formed through the evolution of massive binaries or in dense star clusters. Measured eccentricities could therefore be used to uniquely identify binary mergers formed through the evolution of triple stars. While our results suggest up to ≈10 detections per year with Advanced-LIGO, the high eccentricities could render the merging binaries harder to detect with planned space based interferometers such as LISA.« less

The effects of external planets on inner systems: multiplicities, inclinations and pathways to eccentric warm Jupiters

NASA Astrophysics Data System (ADS)

Mustill, Alexander J.; Davies, Melvyn B.; Johansen, Anders

2017-07-01

We study how close-in systems such as those detected by Kepler are affected by the dynamics of bodies in the outer system. We consider two scenarios: outer systems of giant planets potentially unstable to planet-planet scattering and wide binaries that may be capable of driving Kozai or other secular variations of outer planets' eccentricities. Dynamical excitation of planets in the outer system reduces the multiplicity of Kepler-detectable planets in the inner system in ˜20-25 per cent of our systems. Accounting for the occurrence rates of wide-orbit planets and binary stars, ≈18 per cent of close-in systems could be destabilized by their outer companions in this way. This provides some contribution to the apparent excess of systems with a single transiting planet compared to multiple; however, it only contributes at most 25 per cent of the excess. The effects of the outer dynamics can generate systems similar to Kepler-56 (two coplanar planets significantly misaligned with the host star) and Kepler-108 (two significantly non-coplanar planets in a binary). We also identify three pathways to the formation of eccentric warm Jupiters resulting from the interaction between outer and inner systems: direct inelastic collision between an eccentric outer and an inner planet; secular eccentricity oscillations that may 'freeze out' when scattering resolves in the outer system; and scattering in the inner system followed by 'uplift', where inner planets are removed by interaction with the outer planets. In these scenarios, the formation of eccentric warm Jupiters is a signature of a past history of violent dynamics among massive planets beyond ˜1 au.

News From The Erebos Project

NASA Astrophysics Data System (ADS)

Schaffenroth, Veronika; Barlow, Brad; Geier, Stephan; Vučković, Maja; Kilkenny, Dave; Schaffenroth, Johannes

2017-12-01

Planets and brown dwarfs in close orbits will interact with their host stars, as soon as the stars evolve to become red giants. However, the outcome of those interactions is still unclear. Recently, several brown dwarfs have been discovered orbiting hot subdwarf stars at very short orbital periods of 0.065 - 0.096 d. More than 8% of the close hot subdwarf binaries might have sub-stellar companions. This shows that such companions can significantly affect late stellar evolution and that sdB binaries are ideal objects to study this influence. Thirty-eight new eclipsing sdB binary systems with cool low-mass companions and periods from 0.05 to 0.5 d were discovered based on their light curves by the OGLE project. In the recently published catalog of eclipsing binaries in the Galactic bulge, we discovered 75 more systems. We want to use this unique and homogeneously selected sample to derive the mass distribution of the companions, constrain the fraction of sub-stellar companions and determine the minimum mass needed to strip off the red-giant envelope. We are especially interested in testing models that predict hot Jupiter planets as possible companions. Therefore, we started the EREBOS (Eclipsing Reflection Effect Binaries from the OGLE Survey) project, which aims at analyzing those new HW Vir systems based on a spectroscopic and photometric follow up. For this we were granted an ESO Large Program for ESO-VLT/FORS2. Here we give an update on the the current status of the project and present some preliminary results.

Stability of Multi-Planet Systems Orbiting in the Alpha Centauri AB System

NASA Astrophysics Data System (ADS)

Lissauer, Jack

2018-04-01

We evaluate how closely-spaced planetary orbits in multiple planet systems can be and still survive for billion-year timescales within the alpha Centauri AB system. Although individual planets on nearly circular, coplanar orbits can survive throughout the habitable zones of both stars, perturbations from the companion star imply that the spacing of such planets in multi-planet systems must be significantly larger than the spacing of similar systems orbiting single stars in order to be long-lived. Because the binary companion induces a forced eccentricity upon circumstellar planets, stable orbits with small initial eccentricities aligned with the binary orbit are possible to slightly larger initial semimajor axes than are initially circular orbits. Initial eccentricities close to the appropriate forced eccentricity can have a much larger affect on how closely planetary orbits can be spaced, on how many planets may remain in the habitable zones, although the required spacing remains significantly higher than for planets orbiting single stars.

Orbital Period Variations in the NY Vir System, Revisited in the Light of New Data

NASA Astrophysics Data System (ADS)

Baştürk, Özgür; Esmer, Ekrem Murat

2018-02-01

NY Virginis is an eclipsing binary system with a subdwarf B primary and an M type dwarf secondary. Recent studies (Qian et al. 2012; Lee et al. 2014) suggested the presence of two circumbinary planets with a few Jovian masses within the system. Lee et al. (2014) examined the orbital stabilities of the suggested planets, using the best-fit parameters derived from their eclipse timing variation analysis. They found that the outer companion should be ejected from the system in about 800 000 years. An observational report from Pulley et al. (2016) pointed out that the recent mideclipse times of the binary deviate significantly from the models suggested by Lee et al. (2014). In fact, variations in the orbital period of the system had already been recognized by many authors, but the parameters of these variations vary significantly as new data accumulate. Here, we analyze the eclipse timing variations of the NY Vir system, using new mid-eclipse times that we have obtained together with earlier published measurements in order to understand the nature of the system and constrain its parameters.

Observations and Analysis of the F-type Near-Contact Binary, NSVS 1054 1123

NASA Astrophysics Data System (ADS)

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

2018-01-01

NSVS 1054 1123 is a F2±2 type (T~ 6750K) eclipsing binary. It was observed in April and May, 2015 at the Appalachian State University’s Dark Sky Observatory in North Carolina with the 32-inch telescope. Six times of minimum light were determined from our present observations, which include two primary eclipses and four secondary eclipses:HJD Min I = 2457113.9330 ±0. 0.0002, 24 57147.8761 ±0.0001,HJD Min II = 2457117.80391 ±0.0006, 2457136.8600 ±0. 0007, 2457148.77040 ±0.0004, 2457151.7468 ±0.0002In addition, six observations at minima were introduced as low weighted times of minimum light taken from archived NSVS Data.The following quadratic ephemerides was determined from all available times of minimum light:JD Hel Min I=2457147.87646±0.00049d + 0 .5954966±0.0000065 X E -0.0000000017± 0.0000000007 X E2A period decrease may indicate that the binary is undergoing magnetic braking and is approaching its contact configuration. A BVRcIc simultaneous (preliminary) Wilson-Devinney Program (W-D) solution indicates that the system has a mass ratio of 0.5828±0.0004, and a component temperature difference of 2350 K. The large DT in the components verify that the binary is not in contact. A Binary Maker fitted hot spot altered slightly but was not eliminated in the WD Synthetic Light Curve Computations. It remains on the larger component at the equator on the correct (following) side for a stream spot directed from the secondary component (as dictated by the Coriolis effect). This could indicate that the components are near filling their respective Roche Lobes. The fill-out of our model is -0.036 for the primary component and -0.048 for the secondary component. The inclination is ~79 degrees, not enough for the system to undergo a total eclipse.Additional and more detailed information is given in this report.

New Pleiades Eclipsing Binaries and a Hyades Transiting System Identified by K2

NASA Astrophysics Data System (ADS)

David, Trevor J.; Conroy, Kyle E.; Hillenbrand, Lynne A.; Stassun, Keivan G.; Stauffer, John; Rebull, Luisa M.; Cody, Ann Marie; Isaacson, Howard; Howard, Andrew W.; Aigrain, Suzanne

2016-05-01

We present the discovery in Kepler’s K2 mission observations and our follow-up radial velocity (RV) observations from Keck/HIRES for four eclipsing binary (EB) star systems in the young benchmark Pleiades and Hyades clusters. Based on our modeling results, we announce two new low mass ({M}{tot}\\lt 0.6 {M}⊙ ) EBs among Pleiades members (HCG 76 and MHO 9) and we report on two previously known Pleiades binaries that are also found to be EB systems (HII 2407 and HD 23642). We measured the masses of the binary HCG 76 to ≲2.5% precision, and the radii to ≲4.5% precision, which together with the precise effective temperatures yield an independent Pleiades distance of 132 ± 5 pc. We discuss another EB toward the Pleiades that is a possible but unlikely Pleiades cluster member (AK II 465). The two new confirmed Pleiades systems extend the mass range of Pleiades EB components to 0.2-2 {M}⊙ . Our initial measurements of the fundamental stellar parameters for the Pleiades EBs are discussed in the context of the current stellar models and the nominal cluster isochrone, finding good agreement with the stellar models of Baraffe et al. at the nominal Pleiades age of 120 Myr. Finally, in the Hyades, we report a new low mass eclipsing system (vA 50) that was concurrently discovered and studied by Mann et al. We confirm that the eclipse is likely caused by a Neptune-sized transiting planet, and with the additional RV constraints presented here we improve the constraint on the maximum mass of the planet to be ≲1.2 MJup.

CONSTRAINING RELATIVISTIC BOW SHOCK PROPERTIES IN ROTATION-POWERED MILLISECOND PULSAR BINARIES.

PubMed

Wadiasingh, Zorawar; Harding, Alice K; Venter, Christo; Böttcher, Markus; Baring, Matthew G

2017-04-20

Multiwavelength followup of unidentified Fermi sources has vastly expanded the number of known galactic-field "black widow" and "redback" millisecond pulsar binaries. Focusing on their rotation-powered state, we interpret the radio to X-ray phenomenology in a consistent framework. We advocate the existence of two distinct modes differing in their intrabinary shock orientation, distinguished by the phase-centering of the double-peaked X-ray orbital modulation originating from mildly-relativistic Doppler boosting. By constructing a geometric model for radio eclipses, we constrain the shock geometry as functions of binary inclination and shock stand-off R 0 . We develop synthetic X-ray synchrotron orbital light curves and explore the model parameter space allowed by radio eclipse constraints applied on archetypal systems B1957+20 and J1023+0038. For B1957+20, from radio eclipses the stand-off is R 0 ~ 0.15-0.3 fraction of binary separation from the companion center, depending on the orbit inclination. Constructed X-ray light curves for B1957+20 using these values are qualitatively consistent with those observed, and we find occultation of the shock by the companion as a minor influence, demanding significant Doppler factors to yield double peaks. For J1023+0038, radio eclipses imply R 0 ≲ 0.4 while X-ray light curves suggest 0.1 ≲ R 0 ≲ 0.3 (from the pulsar). Degeneracies in the model parameter space encourage further development to include transport considerations. Generically, the spatial variation along the shock of the underlying electron power-law index should yield energy-dependence in the shape of light curves motivating future X-ray phase-resolved spectroscopic studies to probe the unknown physics of pulsar winds and relativistic shock acceleration therein.

X-RAY SPECTROSCOPY OF THE HIGH-MASS X-RAY BINARY PULSAR CENTAURUS X-3 OVER ITS BINARY ORBIT

DOE Office of Scientific and Technical Information (OSTI.GOV)

Naik, Sachindra; Ali, Zulfikar; Paul, Biswajit, E-mail: snaik@prl.res.in

2011-08-20

We present a comprehensive spectral analysis of the high-mass X-ray binary (HMXB) pulsar Centaurus X-3 with the Suzaku observatory covering nearly one orbital period. The light curve shows the presence of extended dips which are rarely seen in HMXBs. These dips are seen up to as high as {approx}40 keV. The pulsar spectra during the eclipse, out-of-eclipse, and dips are found to be well described by a partial covering power-law model with high-energy cutoff and three Gaussian functions for 6.4 keV, 6.7 keV, and 6.97 keV iron emission lines. The dips in the light curve can be explained by themore » presence of an additional absorption component with high column density and covering fraction, the values of which are not significant during the rest of the orbital phases. The iron line parameters during the dips and eclipse are significantly different compared to those during the rest of the observation. During the dips, the iron line intensities are found to be lesser by a factor of 2-3 with a significant increase in the line equivalent widths. However, the continuum flux at the corresponding orbital phase is estimated to be lesser by more than an order of magnitude. Similarities in the changes in the iron line flux and equivalent widths during the dips and eclipse segments suggest that the dipping activity in Cen X-3 is caused by an obscuration of the neutron star by dense matter, probably structures in the outer region of the accretion disk, as in the case of dipping low-mass X-ray binaries.« less

CONSTRAINING RELATIVISTIC BOW SHOCK PROPERTIES IN ROTATION-POWERED MILLISECOND PULSAR BINARIES

PubMed Central

Wadiasingh, Zorawar; Harding, Alice K.; Venter, Christo; Böttcher, Markus; Baring, Matthew G.

2018-01-01

Multiwavelength followup of unidentified Fermi sources has vastly expanded the number of known galactic-field “black widow” and “redback” millisecond pulsar binaries. Focusing on their rotation-powered state, we interpret the radio to X-ray phenomenology in a consistent framework. We advocate the existence of two distinct modes differing in their intrabinary shock orientation, distinguished by the phase-centering of the double-peaked X-ray orbital modulation originating from mildly-relativistic Doppler boosting. By constructing a geometric model for radio eclipses, we constrain the shock geometry as functions of binary inclination and shock stand-off R0. We develop synthetic X-ray synchrotron orbital light curves and explore the model parameter space allowed by radio eclipse constraints applied on archetypal systems B1957+20 and J1023+0038. For B1957+20, from radio eclipses the stand-off is R0 ~ 0.15–0.3 fraction of binary separation from the companion center, depending on the orbit inclination. Constructed X-ray light curves for B1957+20 using these values are qualitatively consistent with those observed, and we find occultation of the shock by the companion as a minor influence, demanding significant Doppler factors to yield double peaks. For J1023+0038, radio eclipses imply R0 ≲ 0.4 while X-ray light curves suggest 0.1 ≲ R0 ≲ 0.3 (from the pulsar). Degeneracies in the model parameter space encourage further development to include transport considerations. Generically, the spatial variation along the shock of the underlying electron power-law index should yield energy-dependence in the shape of light curves motivating future X-ray phase-resolved spectroscopic studies to probe the unknown physics of pulsar winds and relativistic shock acceleration therein. PMID:29651167

Photometric Properties of the HW Vir-type Binary OGLE-GD-ECL-11388

NASA Astrophysics Data System (ADS)

Hong, Kyeongsoo; Lee, Jae Woo; Lee, Dong-Joo; Kim, Seung-Lee; Koo, Jae-Rim; Park, Jang-Ho; Lee, Chung-Uk; Kim, Dong-Jin; Cha, Sang-Mok; Lee, Yongseok

2017-01-01

We present the first extensive photometric results for the eclipsing binary OGLE-GD-ECL-11388 with a period of about 3.5 hours located in the Galactic disk. For the photometric solutions, we obtained the BVI light curves from both the KMTNet observations in 2015 and the OGLE-III survey data from 2001-2009, which show striking reflection effects and very sharp eclipses. The light curve synthesis indicates that the eclipsing system is a HW Vir-type binary with a mass ratio of q = 0.289, an orbital inclination of i = 81.9 deg, and a temperature ratio between both components of T 2/T 1 = 0.091. A frequency analysis was applied to the light residuals from our binary model; however, no pulsating periodicity from the subdwarf B-type primary component was detected under signal-to-noise amplitude ratios larger than 4.0. A total of 27 minimum epochs spanning 15 yr were used to analyze the eclipse timing variations of OGLE-GD-ECL-11388. It was found that the orbital period has varied due to a continuous period decrease at a rate of dP/dt = -1.1 × 10-8 day yr-1 or a sinusoidal oscillation with a semiamplitude of K = 35 s and a cycle of P 3 = 8.9 yr. The period decrease may be explained by an angular momentum loss via magnetic stellar wind braking or may be only a part of the sinusoidal variation. We think the most likely interpretation of the orbital period change, at present, is the light-time effect via the presence of a third body with a mass of {M}3\\sin {i}3=12.5 M Jup, putting it in the boundary zone between planets and brown dwarfs.

Constraining Relativistic Bow Shock Properties in Rotation-Powered Millisecond Pulsar Binaries

NASA Technical Reports Server (NTRS)

Wadiasingh, Zorawar; Harding, Alice K.; Venter, Christo; Bottcher, Markus; Baring, Matthew G.

2017-01-01

Multiwavelength follow-up of unidentified Fermi sources has vastly expanded the number of known galactic-field "black widow" and "redback" millisecond pulsar binaries. Focusing on their rotation-powered state, we interpret the radio to X-ray phenomenology in a consistent framework. We advocate the existence of two distinct modes differing in their intrabinary shock orientation, distinguished by the phase-centering of the double-peaked X-ray orbital modulation originating from mildly-relativistic Doppler boosting. By constructing a geometric model for radio eclipses, we constrain the shock geometry as functions of binary inclination and shock stand-off R(sub 0). We develop synthetic X-ray synchrotron orbital light curves and explore the model parameter space allowed by radio eclipse constraints applied on archetypal systems B1957+20 and J1023+0038. For B1957+20, from radio eclipses the stand-off is R(sub 0) approximately 0:15 - 0:3 fraction of binary separation from the companion center, depending on the orbit inclination. Constructed X-ray light curves for B1957+20 using these values are qualitatively consistent with those observed, and we find occultation of the shock by the companion as a minor influence, demanding significant Doppler factors to yield double peaks. For J1023+0038, radio eclipses imply R(sub 0) is approximately less than 0:4 while X-ray light curves suggest 0:1 is approximately less than R(sub 0) is approximately less than 0:3 (from the pulsar). Degeneracies in the model parameter space encourage further development to include transport considerations. Generically, the spatial variation along the shock of the underlying electron power-law index should yield energy-dependence in the shape of light curves motivating future X-ray phase-resolved spectroscopic studies to probe the unknown physics of pulsar winds and relativistic shock acceleration therein.

Constraining Relativistic Bow Shock Properties in Rotation-powered Millisecond Pulsar Binaries

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wadiasingh, Zorawar; Venter, Christo; Böttcher, Markus

2017-04-20

Multiwavelength follow-up of unidentified Fermi sources has vastly expanded the number of known galactic-field “black widow” and “redback” millisecond pulsar binaries. Focusing on their rotation-powered state, we interpret the radio to X-ray phenomenology in a consistent framework. We advocate the existence of two distinct modes differing in their intrabinary shock orientation, distinguished by the phase centering of the double-peaked X-ray orbital modulation originating from mildly relativistic Doppler boosting. By constructing a geometric model for radio eclipses, we constrain the shock geometry as functions of binary inclination and shock standoff R {sub 0}. We develop synthetic X-ray synchrotron orbital light curvesmore » and explore the model parameter space allowed by radio eclipse constraints applied on archetypal systems B1957+20 and J1023+0038. For B1957+20, from radio eclipses the standoff is R {sub 0} ∼ 0.15–0.3 fraction of binary separation from the companion center, depending on the orbit inclination. Constructed X-ray light curves for B1957+20 using these values are qualitatively consistent with those observed, and we find occultation of the shock by the companion as a minor influence, demanding significant Doppler factors to yield double peaks. For J1023+0038, radio eclipses imply R {sub 0} ≲ 0.4, while X-ray light curves suggest 0.1 ≲ R {sub 0} ≲ 0.3 (from the pulsar). Degeneracies in the model parameter space encourage further development to include transport considerations. Generically, the spatial variation along the shock of the underlying electron power-law index should yield energy dependence in the shape of light curves, motivating future X-ray phase-resolved spectroscopic studies to probe the unknown physics of pulsar winds and relativistic shock acceleration therein.« less

r-Process Nucleosynthesis in the Early Universe Through Fast Mergers of Compact Binaries in Triple Systems

NASA Astrophysics Data System (ADS)

Bonetti, Matteo; Perego, Albino; Capelo, Pedro R.; Dotti, Massimo; Miller, M. Coleman

2018-05-01

Surface abundance observations of halo stars hint at the occurrence of r-process nucleosynthesis at low metallicity ([Fe/H] < -3), possibly within the first 108 yr after the formation of the first stars. Possible loci of early-Universe r-process nucleosynthesis are the ejecta of either black hole-neutron star or neutron star-neutron star binary mergers. Here, we study the effect of the inclination-eccentricity oscillations raised by a tertiary (e.g. a star) on the coalescence time-scale of the inner compact object binaries. Our results are highly sensitive to the assumed initial distribution of the inner binary semi-major axes. Distributions with mostly wide compact object binaries are most affected by the third object, resulting in a strong increase (by more than a factor of 2) in the fraction of fast coalescences. If instead the distribution preferentially populates very close compact binaries, general relativistic precession prevents the third body from increasing the inner binary eccentricity to very high values. In this last case, the fraction of coalescing binaries is increased much less by tertiaries, but the fraction of binaries that would coalesce within 108 yr even without a third object is already high. Our results provide additional support to the compact-binary merger scenario for r-process nucleosynthesis.

Observations of the Eclipsing Millisecond Pulsar

NASA Astrophysics Data System (ADS)

Bookbinder, Jay

1990-12-01

FRUCHTER et al. (1988a) HAVE RECENTLY DISCOVERED a 1.6 MSEC PULSAR (PSR 1957+20) IN A 9.2 HOUR ECLIPSING BINARY SYSTEM. THE UNUSUAL BEHAVIOR OF THE DISPERSION MEASURE AS A FUNCTION OF ORBITAL PHASE, AND THE DISAPPEARANCE OF THE PULSAR SIGNAL FOR 50 MINUTES DURING EACH ORBIT, IMPLIES THAT THE ECLIPSES ARE DUE TO A PULSAR-INDUCED WIND FLOWING OFF OF THE COMPANION. THE OPTICAL COUNTERPART IS A 21ST MAGNITUDE OBJECT WHICH VARIES IN INTENSITY OVER THE BINARY PERIOD; ACCURATE GROUND-BASED OBSERVATIONS ARE PREVENTED BY THE PROXIMITY (0.7") OF A 20TH MAGNITUDE K DWARF. WE PROPOSE TO OBSERVE THE OPTICAL COUNTERPART IN A TWO-PART STUDY. FIRST, THE WF/PC WILL PROVIDE ACCURATE MULTICOLOR PHOTOMETRY, ENABLING US TO DETERMINE UNCONTAMINATED MAGNITUDES AND COLORS BOTH AT MAXIMUM (ANTI-ECLIPSE) AS WELL AS AT MINIMUM (ECLIPSE). SECOND, WE PROPOSE TO OBSERVE THE EXPECTED UV LINE EMISSION WITH FOS, ALLOWING FOR AN INTIAL DETERMINATION OF THE TEMPERATURE AND DENSITY STRUCTURE AND ABUNDANCES OF THE WIND THAT IS BEING ABLATED FROM THE COMPANION. STUDY OF THIS UNIQUE SYSTEM HOLDS ENORMOUS POTENTIAL FOR THE UNDERSTANDING OF THE RADIATION FIELD OF A MILLISECOND PULSAR AND THE EVOLUTION OF LMXRBs AND MSPs IN GENERAL. WE EXPECT THESE OBSERVATIONS TO PLACE VERY SIGNIFICANT CONTRAINTS ON MODELS OF THIS UNIQUE OBJECT.

Determination of the Fundamental Properties of the Eclipsing Binary V541 Cygni

NASA Astrophysics Data System (ADS)

McGruder, Chima; Torres, Guillermo; Siverd, Robert; Pepper, Joshua; Rodriguez, Joseph; KELT Collaboration

2017-01-01

We report new high-resolution spectroscopic observations of the B-type detached spectroscopic eclipsing binary V541 Cygni (e = 0.465 and P =15.34 days). We combine analysis of these new spectra with analysis of V-band photometry from the literature to obtain the most precise measurements of the fundamental properties of the stars to date (yielding ~1% errors in the masses and ~2% for the radii). A comparison with current stellar evolution models indicates good fits for an age of ~ 200 million years and [Fe/H] ~ -0.2. Available eclipse timings gathered over 40 years were used to re-determine the apsidal motion of the system, dω/dt = 0.993 degs/cent, which is larger than what theory suggests.The SAO REU program was funded in part by the National Science Foundation REU and Department of Defense ASSURE programs under NSF Grant no. 1262851, and by the Smithsonian Institution.

Photometric Analysis of Eclipsing Binary Az Vir

NASA Astrophysics Data System (ADS)

Neugarten, Andrew; Akiba, Tatsuya; Gokhale, Vayujeet

2018-06-01

We present photometric analysis of the eclipsing binary star system Az Vir. Standard BVR filter data were obtained using the 17-inch PlaneWave Instruments CDK telescope at the Truman State University Observatory in Kirksville, Mo and the 31-inch NURO telescope at the Lowell Observatory complex in Flagstaff, AZ. We apply an eight-term truncated Fourier fit to the light curves generated from these data to confirm the classification of Az Vir as a W Ursae Majoris-type eclipsing variable, using criteria specified by Rucinski (1997). We also calculate the values for the O’Connell Effect Ratio (OER) and the Light Curve Asymmetry (LCA) to quantify the asymmetry in the BVR light curves. In addition, we use data provided by the SuperWASP mission to perform long term O-C (observed minus calculated) analysis on the system to determine if and how its period is changing.

Photometric analysis of the eclipsing binary star AI Draconis

NASA Astrophysics Data System (ADS)

Deǧirmenci, Ö. L.; Gülmen, Ö.; Sezer, C.; Erdem, A.; Devlen, A.

2000-11-01

New photometric data from the eclipsing binary star AI Draconis has been analyzed with the method of Wilson-Devinney. The system shows a period increase of about 0.91 sec per century, which corresponds to a mass transfer from the less to the more massive component at a rate of 7.5 10-7 Msun/yr under the conservative mass transfer hypothesis. We also suggest that the system has an unseen component which orbits around the mass center of the triplet system with a period of about 23 yrs. We found that the projectional angular separation between the third star and eclipsing pair varies from 0.048 arcsec to 0.235 arcsec. These results suggestive of a third body should be checked in the future with more sensitive observations. Table 1 is only available electronically with the On-Line publication at http://link.springer.de/link/service/00230/

WHITE-LIGHT FLARES ON CLOSE BINARIES OBSERVED WITH KEPLER

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gao, Qing; Xin, Yu; Liu, Ji-Feng

2016-06-01

Based on Kepler data, we present the results of a search for white light flares on 1049 close binaries. We identify 234 flare binaries, of which 6818 flares are detected. We compare the flare-binary fraction in different binary morphologies (“detachedness”). The result shows that the fractions in over-contact and ellipsoidal binaries are approximately 10%–20% lower than those in detached and semi-detached systems. We calculate the binary flare activity level (AL) of all the flare binaries, and discuss its variations along the orbital period ( P {sub orb}) and rotation period ( P {sub rot}, calculated for only detached binaries). Wemore » find that the AL increases with decreasing P {sub orb} or P {sub rot}, up to the critical values at P {sub orb} ∼ 3 days or P {sub rot} ∼ 1.5 days, and thereafter the AL starts decreasing no matter how fast the stars rotate. We examine the flaring rate as a function of orbital phase in two eclipsing binaries on which a large number of flares are detected. It appears that there is no correlation between flaring rate and orbital phase in these two binaries. In contrast, when we examine the function with 203 flares on 20 non-eclipse ellipsoidal binaries, bimodal distribution of amplitude-weighted flare numbers shows up at orbital phases 0.25 and 0.75. Such variation could be larger than what is expected from the cross section modification.« less

The Kozai-Lidov mechanism in hydrodynamical disks. II. Effects of binary and disk parameters

DOE PAGES

Fu, Wen; Lubow, Stephen H.; Martin, Rebecca G.

2015-07-01

Martin et al. (2014b) showed that a substantially misaligned accretion disk around one component of a binary system can undergo global damped Kozai–Lidov (KL) oscillations. During these oscillations, the inclination and eccentricity of the disk are periodically exchanged. However, the robustness of this mechanism and its dependence on the system parameters were unexplored. In this paper, we use three-dimensional hydrodynamical simulations to analyze how various binary and disk parameters affect the KL mechanism in hydrodynamical disks. The simulations include the effect of gas pressure and viscosity, but ignore the effects of disk self-gravity. We describe results for different numerical resolutions,more » binary mass ratios and orbital eccentricities, initial disk sizes, initial disk surface density profiles, disk sound speeds, and disk viscosities. We show that the KL mechanism can operate for a wide range of binary-disk parameters. We discuss the applications of our results to astrophysical disks in various accreting systems.« less

Effect of intruder mass on collisions with hard binaries. II - Dependence on impact parameter and computations of the interaction cross sections

NASA Astrophysics Data System (ADS)

Hills, J. G.

1992-06-01

Over 125,000 encounters between a hard binary with equal mass, components and orbital eccentricity of 0, and intruders with solar masses ranging from 0.01 to 10,000 are simulated. Each encounter was followed up to a maximum of 5 x 10 exp 6 integration steps to allow long-term 'resonances', temporary trinary systems, to break into a binary and a single star. These simulations were done over a range of impact parameters to find the cross sections for various processes occurring in these encounters. A critical impact parameter found in these simulations is the one beyond which no exchange collisions can occur. The energy exchange between the binary and a massive intruder decreases greatly in collisions with Rmin of not less than Rc. The semimajor axes and orbital eccentricity of the surviving binary also drops rapidly at Rc in encounters with massive intruders. The formation of temporary trinary systems is important for all intruder masses.

The 1982-1984 Eclipse of Epsilon Aurigae

NASA Technical Reports Server (NTRS)

Stencel, R. E. (Editor)

1985-01-01

A workshop proceedings concerned with the new data collected during the 1982-1984 eclipse period of the 27-year system Epsilon Aurigae is presented. This binary star has been a classic problem in astrophysics because the opaque eclipsing object is nonstellar, and probably disk shaped. Invited papers concerning the history of the system, optical, infrared and ultraviolet photometry, optical polarimetry and ultraviolet spectroscopy are included. An invited paper concerning comprehensive theoretical interpretation in the context of stellar evolution also is included. The information collected herein is unparalleled in scope and will remain a standard reference until the next eclipse cycle in the year 2009 A.D., in all probability.

Post-Newtonian Dynamics in Dense Star Clusters: Highly Eccentric, Highly Spinning, and Repeated Binary Black Hole Mergers

NASA Astrophysics Data System (ADS)

Rodriguez, Carl L.; Amaro-Seoane, Pau; Chatterjee, Sourav; Rasio, Frederic A.

2018-04-01

We present models of realistic globular clusters with post-Newtonian dynamics for black holes. By modeling the relativistic accelerations and gravitational-wave emission in isolated binaries and during three- and four-body encounters, we find that nearly half of all binary black hole mergers occur inside the cluster, with about 10% of those mergers entering the LIGO/Virgo band with eccentricities greater than 0.1. In-cluster mergers lead to the birth of a second generation of black holes with larger masses and high spins, which, depending on the black hole natal spins, can sometimes be retained in the cluster and merge again. As a result, globular clusters can produce merging binaries with detectable spins regardless of the birth spins of black holes formed from massive stars. These second-generation black holes would also populate any upper mass gap created by pair-instability supernovae.

Post-Newtonian Dynamics in Dense Star Clusters: Highly Eccentric, Highly Spinning, and Repeated Binary Black Hole Mergers.

PubMed

Rodriguez, Carl L; Amaro-Seoane, Pau; Chatterjee, Sourav; Rasio, Frederic A

2018-04-13

We present models of realistic globular clusters with post-Newtonian dynamics for black holes. By modeling the relativistic accelerations and gravitational-wave emission in isolated binaries and during three- and four-body encounters, we find that nearly half of all binary black hole mergers occur inside the cluster, with about 10% of those mergers entering the LIGO/Virgo band with eccentricities greater than 0.1. In-cluster mergers lead to the birth of a second generation of black holes with larger masses and high spins, which, depending on the black hole natal spins, can sometimes be retained in the cluster and merge again. As a result, globular clusters can produce merging binaries with detectable spins regardless of the birth spins of black holes formed from massive stars. These second-generation black holes would also populate any upper mass gap created by pair-instability supernovae.

THREE NEW ECLIPSING WHITE-DWARF-M-DWARF BINARIES DISCOVERED IN A SEARCH FOR TRANSITING PLANETS AROUND M-DWARFS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Law, Nicholas M.; Kraus, Adam L.; Street, Rachel

2012-10-01

We present three new eclipsing white-dwarf/M-dwarf binary systems discovered during a search for transiting planets around M-dwarfs. Unlike most known eclipsing systems of this type, the optical and infrared emission is dominated by the M-dwarf components, and the systems have optical colors and discovery light curves consistent with being Jupiter-radius transiting planets around early M-dwarfs. We detail the PTF/M-dwarf transiting planet survey, part of the Palomar Transient Factory (PTF). We present a graphics processing unit (GPU)-based box-least-squares search for transits that runs approximately 8 Multiplication-Sign faster than similar algorithms implemented on general purpose systems. For the discovered systems, we decomposemore » low-resolution spectra of the systems into white-dwarf and M-dwarf components, and use radial velocity measurements and cooling models to estimate masses and radii for the white dwarfs. The systems are compact, with periods between 0.35 and 0.45 days and semimajor axes of approximately 2 R{sub Sun} (0.01 AU). The M-dwarfs have masses of approximately 0.35 M{sub Sun }, and the white dwarfs have hydrogen-rich atmospheres with temperatures of around 8000 K and have masses of approximately 0.5 M{sub Sun }. We use the Robo-AO laser guide star adaptive optics system to tentatively identify one of the objects as a triple system. We also use high-cadence photometry to put an upper limit on the white-dwarf radius of 0.025 R{sub Sun} (95% confidence) in one of the systems. Accounting for our detection efficiency and geometric factors, we estimate that 0.08%{sub -0.05%}{sup +0.10%} (90% confidence) of M-dwarfs are in these short-period, post-common-envelope white-dwarf/M-dwarf binaries where the optical light is dominated by the M-dwarf. The lack of detections at shorter periods, despite near-100% detection efficiency for such systems, suggests that binaries including these relatively low-temperature white dwarfs are preferentially found at relatively large orbital radii. Similar eclipsing binary systems can have arbitrarily small eclipse depths in red bands and generate plausible small-planet-transit light curves. As such, these systems are a source of false positives for M-dwarf transiting planet searches. We present several ways to rapidly distinguish these binaries from transiting planet systems.« less

The formation of Kuiper-belt binaries through exchange reactions.

PubMed

Funato, Yoko; Makino, Junichiro; Hut, Piet; Kokubo, Eiichiro; Kinoshita, Daisuke

2004-02-05

Recent observations have revealed that an unexpectedly high fraction--a few per cent--of the trans-Neptunian objects (TNOs) that inhabit the Kuiper belt are binaries. The components have roughly equal masses, with very eccentric orbits that are wider than a hundred times the radius of the primary. Standard theories of binary asteroid formation tend to produce close binaries with circular orbits, so two models have been proposed to explain the unique characteristics of the TNOs. Both models, however, require extreme assumptions regarding the size distribution of the TNOs. Here we report a mechanism that is capable of producing binary TNOs with the observed properties during the early stages of their formation and growth. The only required assumption is that the TNOs were initially formed through gravitational instabilities in the protoplanetary dust disk. The basis of the mechanism is an exchange reaction in which a binary whose primary component is much more massive than the secondary interacts with a third body, whose mass is comparable to that of the primary. The low-mass secondary component is ejected and replaced by the third body in a wide but eccentric orbit.

Probing the low-stellar-mass domain with Kepler and APOGEE observations of eclipsing binaries

NASA Astrophysics Data System (ADS)

Prsa, Andrej; Hambleton, Kelly

2018-01-01

Observations of low-mass stars (M < 0.5 Msun) have been shown to systematically disagree with the predictions of stellar evolutionary models, where observed radii can be inflated by as much as 5-15% as compared to model predictions. One of the proposed explanations for this discrepancy that is gaining traction are stellar magnetic fields impeding the onset of convection and the subsequent bloating of the star. Here we present modeling analysis results of two benchmark eclipsing binaries, KIC 3003991 and KIC 2445134, with low mass companions (M ~ 0.2 MSun and M ~ 0.5 MSun, respectively). The models are based on Kepler photometry and APOGEE spectroscopy. APOGEE is a part of the Sloan spectroscopic survey that observes in the near-infrared, providing greater sensitivity towards fainter, red companions. We combine the binary modeling software PHOEBE with emcee, an affine invariant Markov chain Monte Carlo sampler; celerite, a Gaussian process library; and our own codes to create a modeling suite capable of modeling correlated noise, shot noise, nuisance astrophysical signals (such as spots) and the full set of eclipsing binary parameters. The results are obtained within a probabilistic framework, with robust mass and radius uncertainties ~1-4%. We overplot the derived masses, radii and temperatures over evolutionary models and note stellar size bloating w.r.t. model predictions for both systems. This work has been funded by the NSF grant #1517460.

BVRI Photometric Study of the High Mass Ratio, Detached, Pre-contact W UMa Binary GQ Cancri

NASA Astrophysics Data System (ADS)

Samec, R. G.; Olson, A.; Caton, D.; Faulkner, D. R.

2017-12-01

CCD BVRcIc light curves of GQ Cancri were observed in April 2013 using the SARA North 0.9-meter Telescope at Kitt Peak National Observatory in Arizona in remote mode. It is a high-amplitude (V 0.9 magnitude) K0±V type eclipsing binary (T1 5250 K) with a photometrically-determined mass ratio of M2 / M1 = 0.80. Its spectral color type classifies it as a pre-contact W UMa Binary (PCWB). The Wilson-Devinney Mode 2 solutions show that the system has a detached binary configuration with fill-outs of 94% and 98% for the primary and secondary component, respectively. As expected, the light curve is asymmetric due to spot activity. Three times of minimum light were calculated, for two primary eclipses and one secondary eclipse, from our present observations. In total, some 26 times of minimum light covering nearly 20 years of observation were used to determine linear and quadratic ephemerides. It is noted that the light curve solution remained in a detached state for every iteration of the computer runs. The components are very similar with a computed temperature difference of only 4 K, and the flux of the primary component accounts for 53±55% of the system's light in B, V, Rc, and Ic. A 12-degree radius high latitude white spot (faculae) was iterated on the primary component.

Photometric Study of The Solar Type, Total Eclipsing Binary, TYC 2853-18-1

NASA Astrophysics Data System (ADS)

Samec, Ronald G.; Figg, E. R.; Faulkner, D.; Van Hamme, W.

2009-12-01

We present an analysis of the Solar-Type eclipsing binary, TYC 2853-18-1 (Persei), based on observations taken at the National Undergraduate Research Observatory (NURO) and the Southeastern Association for Research in Astronomy (SARA) in the Fall, 2007 and Spring, 2008. Light curves, a period study and a synthetic light curve solution are presented for this variable which was recently discovered by TYCHO as an eclipsing binary (2006, IBVS 5700). Our CCD observations of TYC 2853-18-1 [GSC 2853 0018, RA(2000) = 02h 47m 07.996s, DEC(2000) = +41° 22’ 32.80"] were taken on 20,27 December, 2007 at Lowell Observatory with the 0.81-m reflector with NURO time and 25 November, 3 December, 2007 and 19 February, 2008 via remote observing from Kitt Peak with SARA. NURO observations were take with the thermoelectrically cooled (<-100C) 2KX2K CCD NASACAM. Standard BVRcIc Johnson-Cousins filters were used. Our light curve solution was calculated with the 2004 Wilson code. Mean times of eclipse include, HJDMinI = 2454516.6131(±0.0005), 2454440.52974(±0.00008), 2454438.7605 (±0.0001), 2454462.6464 (±0.0003), HJDMinII = 2454455.71985 (±0.00060), 255462.7943 (±0.0002). These, including the epoch by ROTSE (2006, IBVS 5699) and the epoch calculated by the Wilson code, yielded the following ephemeris: HJD Hel Min I =2451370.8753(±.0.0010)d + 0.2949039 (±0.0000001)E Our unspotted Wilson code solution reveals TYC 2853-18-1 to be a W-type W UMa contact binary with unequal eclipse depths (amplitudes are 0.72 and 0.61 mags in V). It has shallow contact (8% fill-out) and a brief, but total eclipse. Its curves dictate a mass ratio of 2.62±0.01, a component temperature difference of only 73±5 ° K and an inclination of 82.0±0.2°. Spot activity is indicated by night to night variations. We wish to thank the NURO and SARA for their allocation of observing time, as well as NASA and the AAS for their support in paying for travel and publication expenses.

Period variations of Algol-type eclipsing binaries AD And, TWCas and IV Cas

NASA Astrophysics Data System (ADS)

Parimucha, Štefan; Gajdoš, Pavol; Kudak, Viktor; Fedurco, Miroslav; Vaňko, Martin

2018-04-01

We present new analyses of variations in O – C diagrams of three Algol-type eclipsing binary stars: AD And, TW Cas and IV Cas. We have used all published minima times (including visual and photographic) as well as newly determined ones from our and SuperWasp observations. We determined orbital parameters of 3rd bodies in the systems with statistically significant errors, using our code based on genetic algorithms and Markov chain Monte Carlo simulations. We confirmed the multiple nature of AD And and the triple-star model of TW Cas, and we proposed a quadruple-star model of IV Cas.

Finding False Positives Planet Candidates Due To Background Eclipsing Binaries in K2

NASA Astrophysics Data System (ADS)

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

2016-06-01

We adapt the difference image centroid approach, used for finding background eclipsing binaries, to vet K2 planet candidates. Difference image centroids were used with great success to vet planet candidates in the original Kepler mission, where the source of a transit could be identified by subtracting images of out-of-transit cadences from in-transit cadences. To account for K2's roll pattern, we reconstruct out-of-transit images from cadences that are nearby in both time and spacecraft roll angle. We describe the method and discuss some K2 planet candidates which this method suggests are false positives.

IUE spectra of the eclipsing binary NN Serpentis

NASA Technical Reports Server (NTRS)

Wood, Janet H.; Marsh, Thomas R.

1991-01-01

Low-resolution SWP and LWP IUE spectra are used to fit the temperature and angular radius of the white dwarf in the detached eclipsing binary NN Ser. It is found that the redenning to the system has E(B-V) of 0.05 +/-0.05, the white dwarf temperature is 60,000 +/-10,000 K, and the age of the white dwarf is less than 10 exp 7. The shape of eclipse and the K-magnitude of the secondary star are used to constrain the inclination of the binary and the masses and radii of the two stars. The size of the secondary star relative to its Roche lobe and the age of the white dwarf indicate that mass transfer has not yet occurred and that the system is a precataclysmic variable rather than a cataclysmic variable which has entered the period gap. Fitting the observed magnitude of the sinusoidal modulation with a reprocessing model shows that only when i is approximately equal to 90 deg is the required temperature of the secondary star consistent with these results. For this solution the white dwarf temperature is also consistent with those obtained from the IUE spectra.

Learning a Novel Detection Metric for the Detection of O’Connell Effect Eclipsing Binaries

NASA Astrophysics Data System (ADS)

Johnston, Kyle; Haber, Rana; Knote, Matthew; Caballero-Nieves, Saida Maria; Peter, Adrian; Petit, Véronique

2018-01-01

With the advent of digital astronomy, new benefits and new challenges have been presented to the modern day astronomer. No longer can the astronomer rely on manual processing, instead the profession as a whole has begun to adopt more advanced computational means. Here we focus on the construction and application of a novel time-domain signature extraction methodology and the development of a supporting supervised pattern detection algorithm for the targeted identification of eclipsing binaries which demonstrate a feature known as the O’Connell Effect. A methodology for the reduction of stellar variable observations (time-domain data) into Distribution Fields (DF) is presented. Push-Pull metric learning, a variant of LMNN learning, is used to generate a learned distance metric for the specific detection problem proposed. The metric will be trained on a set of a labelled Kepler eclipsing binary data, in particular systems showing the O’Connell effect. Performance estimates will be presented, as well the results of the detector applied to an unlabeled Kepler EB data set; this work is a crucial step in the upcoming era of big data from the next generation of big telescopes, such as LSST.

Discovery of a Detached, Eclipsing 40 Minute Period Double White Dwarf Binary and a Friend: Implications for He+CO White Dwarf Mergers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Brown, Warren R.; Kilic, Mukremin; Kosakowski, Alekzander

We report the discovery of two detached double white dwarf (WD) binaries, SDSS J082239.546+304857.19 and SDSS J104336.275+055149.90, with orbital periods of 40 and 46 minutes, respectively. The 40 minute system is eclipsing; it is composed of a 0.30 M {sub ⊙} and a 0.52 M {sub ⊙} WD. The 46 minute system is a likely LISA verification binary. The short 20 ± 2 Myr and ∼34 Myr gravitational-wave merger times of the two binaries imply that many more such systems have formed and merged over the age of the Milky Way. We update the estimated Milky Way He+CO WD binarymore » merger rate and affirm our previously published result: He+CO WD binaries merge at a rate at least 40 times greater than the formation rate of stable mass-transfer AM CVn binaries, and so the majority must have unstable mass-transfer. The implication is that spin–orbit coupling in He+CO WD mergers is weak, or perhaps nova-like outbursts drive He+CO WDs into merger, as proposed by Shen.« less

Photometric Solutions of Three Eclipsing Binary Stars Observed from Dome A, Antarctica

NASA Astrophysics Data System (ADS)

Liu, N.; Fu, J. N.; Zong, W.; Wang, L. Z.; Uddin, S. A.; Zhang, X. B.; Zhang, Y. P.; Cang, T. Q.; Li, G.; Yang, Y.; Yang, G. C.; Mould, J.; Morrell, N.

2018-04-01

Based on spectroscopic observations for the eclipsing binaries CSTAR 036162 and CSTAR 055495 with the WiFeS/2.3 m telescope at SSO and CSTAR 057775 with the Mage/Magellan I at LCO in 2017, stellar parameters are derived. More than 100 nights of almost-continuous light curves reduced from the time-series photometric observations by CSTAR at Dome A of Antarctic in i in 2008 and in g and r in 2009, respectively, are applied to find photometric solutions for the three binaries with the Wilson–Devinney code. The results show that CSTAR 036162 is a detached configuration with the mass ratio q = 0.354 ± 0.0009, while CSTAR 055495 is a semi-detached binary system with the unusual q = 0.946 ± 0.0006, which indicates that CSTAR 055495 may be a rare binary system with mass ratio close to one and the secondary component filling its Roche Lobe. This implies that a mass-ratio reversal has just occurred and CSTAR 055495 is in a rapid mass-transfer stage. Finally, CSTAR 057775 is believed to be an A-type W UMa binary with q = 0.301 ± 0.0008 and a fill-out factor of f = 0.742(8).

Reducing junk radiation and eccentricity in binary-black-hole initial data

NASA Astrophysics Data System (ADS)

Lovelace, Geoffrey; Pfeiffer, Harald; Brown, Duncan; Lindblom, Lee; Scheel, Mark; Kidder, Lawrence

2007-04-01

Numerical simulations of binary-black-hole (BBH) collisions require initial data that satisfy the Einstein constraint equations. Several well-known methods generate constraint-satisfying BBH data, but the commonly-used simplifying assumptions lead to undesirable effects. BBH data typically assume a conformally flat spatial metric; this leads to an initial pulse of unphysical ``junk'' gravitational radiation. Also, the initial radial velocity of the holes is often neglected; this can lead to significant eccentricity in the holes' trajectories. This talk will discuss efforts to reduce these effects by constructing and evolving generalizations of the BBH initial data of Cook and Pfeiffer (2004). By giving the holes a small radial velocity, the eccentricity can be greatly reduced (although the emitted waves are largely unaffected). The junk radiation for flat and non-flat conformal metrics will also be compared.

Multi-wavelength photometry of the T Tauri binary V582 Mon (KH 15D): A new epoch of occultations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Windemuth, Diana; Herbst, William, E-mail: dwindemuth@wesleyan.edu

2014-01-01

We present multi-wavelength (VRIJHK) observations of KH 15D obtained in 2012/2013, as well as a master table of standard photometry spanning the years 1967 to 2013. The system is a close, eccentric T Tauri binary embedded in an inclined precessing circumbinary (CB) ring. The most recent data show the continued rise of star B with respect to the trailing edge of the occulting horizon as the system's maximum brightness steadily increases. The wealth of data in time and wavelength domains allows us to track the long-term CCD color evolution of KH 15D. We find that the V – I behaviormore » is consistent with direct and scattered light from the composite color of two stars with slightly different temperatures. There is no evidence for any reddening or bluing associated with extinction or scattering by interstellar-medium-size dust grains. Furthermore, we probe the system's faint phase behavior at near-infrared wavelengths in order to investigate extinction properties of the ring and signatures of a possible shepherding planet sometimes invoked to confine the CB ring at ∼5 AU. The wavelength independence of eclipse depth at second contact is consistent with the ring material being fully opaque to 2.2 μm. The color-magnitude diagrams demonstrate excess flux in J and H at low light levels, which may be due to the presence of a hot, young Jupiter-mass planet.« less

Multi-wavelength Photometry of the T Tauri Binary V582 Mon (KH 15D): a New Epoch of Occultations

NASA Astrophysics Data System (ADS)

Windemuth, Diana; Herbst, William

2014-01-01

We present multi-wavelength (VRIJHK) observations of KH 15D obtained in 2012/2013, as well as a master table of standard photometry spanning the years 1967 to 2013. The system is a close, eccentric T Tauri binary embedded in an inclined precessing circumbinary (CB) ring. The most recent data show the continued rise of star B with respect to the trailing edge of the occulting horizon as the system's maximum brightness steadily increases. The wealth of data in time and wavelength domains allows us to track the long-term CCD color evolution of KH 15D. We find that the V - I behavior is consistent with direct and scattered light from the composite color of two stars with slightly different temperatures. There is no evidence for any reddening or bluing associated with extinction or scattering by interstellar-medium-size dust grains. Furthermore, we probe the system's faint phase behavior at near-infrared wavelengths in order to investigate extinction properties of the ring and signatures of a possible shepherding planet sometimes invoked to confine the CB ring at ~5 AU. The wavelength independence of eclipse depth at second contact is consistent with the ring material being fully opaque to 2.2 μm. The color-magnitude diagrams demonstrate excess flux in J and H at low light levels, which may be due to the presence of a hot, young Jupiter-mass planet.

The Great Exoplanet Eclipse: Spitzer Observations of the Benchmark Sub-Saturn-Mass Planet KELT-11b

NASA Astrophysics Data System (ADS)

Colon, Knicole; Beatty, Thomas; Line, Michael; Kreidberg, Laura; Lopez, Eric; Stassun, Keivan; Rodriguez, Joseph; Pepper, Joshua; James, David

2017-10-01

KELT-11b is a unique sub-Saturn-mass planet with a super-Jupiter radius that is in orbit around a bright, metal-rich, sub-giant star. We propose to observe a single eclipse of KELT-11b with Spitzer in IRAC Channel 2, which will allow us to precisely constrain the orbital eccentricity of the planet, study atmospheric circulation in an as yet unexplored regime of planetary surface gravity and temperature, and perform comparative science with other exoplanets in order to explore the correlation between surface gravity and thermal structure. Spitzer is the only active facility capable of providing the high precision, continuous infrared eclipse photometry of KELT-11b that is required to reach these objectives. The Spitzer infrared eclipse combined with near-infrared transmission spectroscopy that we will obtain with WFC3 on the Hubble Space Telescope will ultimately enable a detailed investigation of the atmospheric properties of KELT-11b and will provide a benchmark for planning thermal observations of exoplanets with the James Webb Space Telescope.

Can Eccentric Debris Disks Be Long-lived? A First Numerical Investigation and Application to Zeta(exp 2) Reticuli

NASA Technical Reports Server (NTRS)

Faramaz, V.; Beust, H.; Thebault, P.; Augereau, J.-C.; Bonsor, A.; delBurgo, C.; Ertel, S.; Marshall, J. P.; Milli, J.; Montesinos, B.;

THE PROPERTIES OF HYPERVELOCITY STARS AND S-STARS ORIGINATING FROM AN ECCENTRIC DISK AROUND A SUPERMASSIVE BLACK HOLE

DOE Office of Scientific and Technical Information (OSTI.GOV)

Šubr, Ladislav; Haas, Jaroslav, E-mail: subr@sirrah.troja.mff.cuni.cz, E-mail: haas@sirrah.troja.mff.cuni.cz

2016-09-01

Hypervelocity stars (HVSs), which are observed in the Galactic halo, are believed to be accelerated to large velocities by a process of tidal disruption of binary stars passing close to the supermassive black hole (SMBH) which resides in the center of the Galaxy. It is, however, still unclear where these relatively young stars were born and what dynamical process pushed them to nearly radial orbits around the SMBH. In this paper we investigate the possibility that the young binaries originated from a thin eccentric disk, similar to the one currently observed in the Galactic center. By means of direct Nmore » -body simulations, we follow the dynamical evolution of an initially thin and eccentric disk of stars with a 100% binary fraction orbiting around the SMBH. Such a configuration leads to Kozai–Lidov oscillations of orbital elements, bringing a considerable number of binaries to the close vicinity of the black hole. Subsequent tidal disruption of these binaries accelerates one of their components to velocities well above the escape velocity from the SMBH, while the second component becomes tightly bound to the SMBH. We describe the main kinematic properties of the escaping and tightly bound stars within our model, and compare them qualitatively to the properties of the observed HVSs and S-stars, respectively. The most prominent feature is strong anisotropy in the directions of the escaping stars, which is observed for Galactic HVSs but has not yet been explained.« less

A Detailed Survey of Pulsating Variables in Five Globular Clusters (Abstract)

NASA Astrophysics Data System (ADS)

Murphy, B. W.

2016-12-01

(Abstract only) Globular clusters are ideal laboratories for conducting a stellar census. Of particular interest are pulsating variables, which provide astronomers with a tool to probe the properties of the stars and the cluster. We observed each of five globular clusters hundreds to thousands of times over a time span ranging from 2 to 4 years in B, V, and I filters using the SARA 0.6-meter telescope located at Cerro Tololo Interamerican Observatory and the 0.9-meter telescope located at Kitt Peak, Arizona. The images were analyzed using difference image analysis to identify and produce light curves of all variables found in each cluster. In total we identified 377 variables with 140 of these being newly discovered increasing the number of known variables stars in these clusters by 60%. Of the total we have identified 319 RR Lyrae variables (193 RR0, 18 RR01, 101 RR1, 7 RR2), 9 SX Phe stars, 5 Cepheid variables, 11 eclipsing variables, and 33 long period variables. For IC4499 we identified 64 RR0, 18 RR01, 14 RR1, 4 RR2, 1 SX Phe, 1 eclipsing binary, and 2 long period variables. For NGC4833 we identified 10 RR0, 7 RR1, 3 RR2, 6 SX Phe, 5 eclipsing binaries, and 9 long period variables. For NGC6171 (M107) we identified 14 RR0, 7 RR1, and 1 SX Phe. For NGC6402 (M14) we identified 55 RR0, 57 RR1, 1 RR2, 1 SX Phe, 6 Cepheids, 1 eclipsing binary, and 15 long period variables. For NGC6584 we identified 50 RR0, 16 RR1, 4 eclipsing binaries, and 7 long period variables. From our extensive data set we were able to obtain sufficient temporal and complete phase coverage of the RR Lyrae variables. This has allowed us not only to properly classify each of the RR Lyrae variables but also to use Fourier decomposition of the B, V, and I light curves to further analyze the properties of the variable stars and hence the physical properties of each globular cluster.

NEAR-INFRARED THERMAL EMISSION FROM THE HOT JUPITER TrES-2b: GROUND-BASED DETECTION OF THE SECONDARY ECLIPSE

DOE Office of Scientific and Technical Information (OSTI.GOV)

Croll, Bryce; Jayawardhana, Ray; Albert, Loic

2010-07-10

We present near-infrared Ks-band photometry bracketing the secondary eclipse of the hot Jupiter TrES-2b using the Wide-field Infrared Camera on the Canada-France-Hawaii Telescope. We detect its thermal emission with an eclipse depth of 0.062{sup +0.013}{sub -0.011}% (5{sigma}). Our best-fit secondary eclipse is consistent with a circular orbit (a 3{sigma} upper limit on the eccentricity, e, and argument or periastron, {omega}, of |e cos {omega}| < 0.0090), in agreement with mid-infrared detections of the secondary eclipse of this planet. A secondary eclipse of this depth corresponds to a dayside Ks-band brightness temperature of T{sub B} = 1636{sup +79}{sub -88} K. Ourmore » thermal emission measurement, when combined with the thermal emission measurements using Spitzer/IRAC from O'Donovan and collaborators, suggests that this planet exhibits relatively efficient dayside to nightside redistribution of heat and a near isothermal dayside atmospheric temperature structure, whose spectrum is well approximated by a blackbody. It is unclear if the atmosphere of TrES-2b requires a temperature inversion; if it does it is likely due to chemical species other than TiO/VO as the atmosphere of TrES-2b is too cool to allow TiO/VO to remain in gaseous form. Our secondary eclipse has the smallest depth of any detected from the ground, at around 2 {mu}m, to date.« less

Absolute parameters for AI Phoenicis using WASP photometry

NASA Astrophysics Data System (ADS)

Kirkby-Kent, J. A.; Maxted, P. F. L.; Serenelli, A. M.; Turner, O. D.; Evans, D. F.; Anderson, D. R.; Hellier, C.; West, R. G.

2016-06-01

Context. AI Phe is a double-lined, detached eclipsing binary, in which a K-type sub-giant star totally eclipses its main-sequence companion every 24.6 days. This configuration makes AI Phe ideal for testing stellar evolutionary models. Difficulties in obtaining a complete lightcurve mean the precision of existing radii measurements could be improved. Aims: Our aim is to improve the precision of the radius measurements for the stars in AI Phe using high-precision photometry from the Wide Angle Search for Planets (WASP), and use these improved radius measurements together with estimates of the masses, temperatures and composition of the stars to place constraints on the mixing length, helium abundance and age of the system. Methods: A best-fit ebop model is used to obtain lightcurve parameters, with their standard errors calculated using a prayer-bead algorithm. These were combined with previously published spectroscopic orbit results, to obtain masses and radii. A Bayesian method is used to estimate the age of the system for model grids with different mixing lengths and helium abundances. Results: The radii are found to be R1 = 1.835 ± 0.014 R⊙, R2 = 2.912 ± 0.014 R⊙ and the masses M1 = 1.1973 ± 0.0037 M⊙, M2 = 1.2473 ± 0.0039 M⊙. From the best-fit stellar models we infer a mixing length of 1.78, a helium abundance of YAI = 0.26 +0.02-0.01 and an age of 4.39 ± 0.32 Gyr. Times of primary minimum show the period of AI Phe is not constant. Currently, there are insufficient data to determine the cause of this variation. Conclusions: Improved precision in the masses and radii have improved the age estimate, and allowed the mixing length and helium abundance to be constrained. The eccentricity is now the largest source of uncertainty in calculating the masses. Further work is needed to characterise the orbit of AI Phe. Obtaining more binaries with parameters measured to a similar level of precision would allow us to test for relationships between helium abundance and mixing length.

Kepler-16: a transiting circumbinary planet.

PubMed

Doyle, Laurance R; Carter, Joshua A; Fabrycky, Daniel C; Slawson, Robert W; Howell, Steve B; Winn, Joshua N; Orosz, Jerome A; Prša, Andrej; Welsh, William F; Quinn, Samuel N; Latham, David; Torres, Guillermo; Buchhave, Lars A; Marcy, Geoffrey W; Fortney, Jonathan J; Shporer, Avi; Ford, Eric B; Lissauer, Jack J; Ragozzine, Darin; Rucker, Michael; Batalha, Natalie; Jenkins, Jon M; Borucki, William J; Koch, David; Middour, Christopher K; Hall, Jennifer R; McCauliff, Sean; Fanelli, Michael N; Quintana, Elisa V; Holman, Matthew J; Caldwell, Douglas A; Still, Martin; Stefanik, Robert P; Brown, Warren R; Esquerdo, Gilbert A; Tang, Sumin; Furesz, Gabor; Geary, John C; Berlind, Perry; Calkins, Michael L; Short, Donald R; Steffen, Jason H; Sasselov, Dimitar; Dunham, Edward W; Cochran, William D; Boss, Alan; Haas, Michael R; Buzasi, Derek; Fischer, Debra

2011-09-16

We report the detection of a planet whose orbit surrounds a pair of low-mass stars. Data from the Kepler spacecraft reveal transits of the planet across both stars, in addition to the mutual eclipses of the stars, giving precise constraints on the absolute dimensions of all three bodies. The planet is comparable to Saturn in mass and size and is on a nearly circular 229-day orbit around its two parent stars. The eclipsing stars are 20 and 69% as massive as the Sun and have an eccentric 41-day orbit. The motions of all three bodies are confined to within 0.5° of a single plane, suggesting that the planet formed within a circumbinary disk.

INFERRING THE ECCENTRICITY DISTRIBUTION

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hogg, David W.; Bovy, Jo; Myers, Adam D., E-mail: david.hogg@nyu.ed

2010-12-20

Standard maximum-likelihood estimators for binary-star and exoplanet eccentricities are biased high, in the sense that the estimated eccentricity tends to be larger than the true eccentricity. As with most non-trivial observables, a simple histogram of estimated eccentricities is not a good estimate of the true eccentricity distribution. Here, we develop and test a hierarchical probabilistic method for performing the relevant meta-analysis, that is, inferring the true eccentricity distribution, taking as input the likelihood functions for the individual star eccentricities, or samplings of the posterior probability distributions for the eccentricities (under a given, uninformative prior). The method is a simple implementationmore » of a hierarchical Bayesian model; it can also be seen as a kind of heteroscedastic deconvolution. It can be applied to any quantity measured with finite precision-other orbital parameters, or indeed any astronomical measurements of any kind, including magnitudes, distances, or photometric redshifts-so long as the measurements have been communicated as a likelihood function or a posterior sampling.« less

Line profiles variations from atmospheric eclipses: Constraints on the wind structure in Wolf-Rayet stars

NASA Technical Reports Server (NTRS)

Auer, L. H.; Koenigsberger, G.

1994-01-01

Binary systems in which one of the components has a stellar wind may present a phenomenon known as 'wind' or 'atmospheric eclipse', in which that wind occults the luminous disk of the companion. The enhanced absorption profile, relative to the spectrum at uneclipsed orbital phases, can be be modeled to yield constraints on the spatial structure of the eclipsing wind. A new, very efficient approach to the radiative transfer problem, which makes no requirements with respect to monotonicity of the velocity gradient or size of that gradient, is presented. The technique recovers both the comoving frame calculation and the Sobolev approximation in the appropiate limits. Sample computer simulations of the line profile variations induced by wind eclipses are presented. It is shown that the location of the wind absorption features in frequency is a diagnostic tool for identifying the size of the wind acceleration region. Comparison of the model profile variations with the observed variations in the Wolf-Rayet (W-R)+6 binary system V444 Cyg illustrate how the method can be used to derive information on the structure of the wind of the W-R star constrain the size of the W-R core radius.

Planet formation in binary systems: simulating coagulation using analytically determined collision velocities.

NASA Astrophysics Data System (ADS)

Silsbee, Kedron; Rafikov, Roman

2017-06-01

The existence of planets in tight binary systems presents an interesting puzzle. It is thought that cores of giant planets form via agglomeration of planetesimals in mutual collisions. However, in tight binary systems, one would naïvely expect the collision velocities between planetesimals to be so high that even 100 km bodies would be destroyed, rather than growing in mutual collisions. In these systems, planetesimals are perturbed by gravity from the companion star, and gravity and gas drag from a massive eccentric gas disk. There is a damaging secular resonance that occurs due to the combination of disk gravity and gravity from the binary companion, however the disk gravity can also create locations of low relative eccentricity between planetesimals of different sizes that would not exist if the disk gravity were ignored. Because the gas drag acts more strongly on smaller planetesimals, orbital eccentricity and apsidal angle depend on planetesimal size. Consequently, planetesimal collision velocities depend on the sizes of the collision partners. Same-size bodies collide at low velocity because their orbits are apsidally aligned. Therefore, often in a given environment some collisions will lead to planetesimal growth, and some to erosion or destruction. This variety of collisional outcomes makes it difficult to determine whether any planetesimals can grow to large sizes. We run a multi-annulus coagulation/fragmentation simulation that also includes the effect of size-dependent radial drift of planetesimals to determine the minimum size of initial planetesimal necessary for growth to large sizes in collisions. The minimum initial size of planetesimal necessary for growth depends greatly on the disk mass, eccentricity and the degree of apsidal alignment with the binary. We find that in a wide variety of situations, it is a reasonable approximation that growth occurs as long as there are no collisions capable of completely destroying a planetesimal, but erosion by moderately damaging collisions can also prevent growth from occurring.

Spectral Eclipse Timing

NASA Astrophysics Data System (ADS)

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.

The Influence of Mass Loss on the Eccentricity of Double Star Orbits

NASA Astrophysics Data System (ADS)

Docobo, J. A.; Prieto, C.; Ling, J. F.

In this comunication we study the behaviour of the eccentricity of double star orbits (visual and wide spectroscopic binaries) according to simplified laws of mass loss. Applications to the systems WDS 05245S0224 - HD 35411, WDS 05387S0236 - HD 37468 and WDS 06154S0902 - HD 43362 are included.

Birth of millisecond pulsars in globular clusters

NASA Technical Reports Server (NTRS)

Grindlay, J. E.; Bailyn, C. D.

1988-01-01

It is argued here that accretion-induced collapse of white dwarfs in binaries can form millisecond pulsars directly without requiring a precursor low-mass X-ray binary stage. Ablation of the precollapse binary companion by the millisecond pulsar's radiation field, a process invoked to explain some of the characteristics of the recently discovered eclipsing millisecond pulsar, can then yield isolated neutron stars witout requiring an additional stellar encounter.

Constraining stellar binary black hole formation scenarios with eLISA eccentricity measurements

NASA Astrophysics Data System (ADS)

Nishizawa, Atsushi; Sesana, Alberto; Berti, Emanuele; Klein, Antoine

2017-03-01

A space-based interferometer such as the evolved Laser Interferometer Space Antenna (eLISA) could observe a few to a few thousands of progenitors of black hole binaries (BHBs) similar to those recently detected by Advanced LIGO. Gravitational radiation circularizes the orbit during inspiral, but some BHBs retain a measurable eccentricity at the low frequencies where eLISA is the most sensitive. The eccentricity of a BHB carries precious information about its formation channel: BHBs formed in the field, in globular clusters, or close to a massive black hole (MBH) have distinct eccentricity distributions in the eLISA band. We generate mock eLISA observations, folding in measurement errors, and using a Bayesian model selection, we study whether eLISA measurements can identify the BHB formation channel. We find that a handful of observations would suffice to tell whether BHBs were formed in the gravitational field of an MBH. Conversely, several tens of observations are needed to tell apart field formation from globular cluster formation. A 5-yr eLISA mission with the longest possible armlength is desirable to shed light on BHB formation scenarios.

Constraining stellar binary black hole formation scenarios with LISA eccentricity measurements

NASA Astrophysics Data System (ADS)

Berti, Emanuele; Nishizawa, Atsushi; Sesana, Alberto; Klein, Antoine

2017-01-01

A space-based interferometer such as LISA could observe few to few thousands progenitors of black hole binaries (BHBs) similar to those recently detected by Advanced LIGO. Gravitational radiation circularizes the orbit during inspiral, but some BHBs retain a measurable eccentricity at the low frequencies where LISA is most sensitive. The eccentricity of a BHB carries precious information about its formation channel: BHBs formed in the field, in globular clusters, or close to a massive black hole (MBH) have distinct eccentricity distributions in the LISA band. We generate mock LISA observations, folding in measurement errors, and using Bayesian model selection we study whether LISA measurements can identify the BHB formation channel. We find that a handful of observations would suffice to tell whether BHBs were formed in the gravitational field of a MBH. Conversely, several tens of observations are needed to tell apart field formation from globular cluster formation. A five-year LISA mission with the longest possible armlength is desirable to shed light on BHB formation scenarios. NSF CAREER Grant No. PHY-1055103, NSF Grant No. PHY-1607130, FCT contract IF/00797/2014/CP1214/CT0012.

Simultaneous CCD Photometry of Two Eclipsing Binary Stars in Pegasus - Part2: BX Peg

NASA Astrophysics Data System (ADS)

Alton, K. B.

2013-05-01

BX Peg is an overcontact W UMa binary system (P = 0.280416 d) which has been rather well studied, but not fully understood due to complex changes in eclipse timings and light curve variations attributed to star spots. Photometric data collected in three bandpasses (B, V, and Ic) produced nineteen new times of minimum for BX Peg. These were used to update the linear ephemeris and further analyze potential changes in orbital periodicity by examining long-term changes in eclipse timings. In addition, synthetic fitting of light curves by Roche modeling was accomplished with the assistance of three different programs, two of which employ the Wilson-Devinney code. Different spotted solutions were necessary to achieve the best Roche model fits for BX Peg light curves collected in 2008 and 2011. Overall, the long-;term decrease (9.66 × 10-3 sec y-1) in orbital period defined by the parabolic fit of eclipse timing data could arise from mass transfer or angular momentum loss. The remaining residuals from observed minus predicted eclipse timings for BX Peg exhibit complex but non-random behavior. These may be related to magnetic activity cycles and/or the presence of an unseen mass influencing the times of minimum, however, additional minima need to be collected over a much longer timescale to resolve the nature of these complex changes.

Recent Uhuru results on Centaurus X-3

NASA Technical Reports Server (NTRS)

Schreier, E. J.; Fabbiano, G.

1976-01-01

The current status of the analysis of Cen X-3 data from Uhuru concerning pulsations, orbital period and eccentricity, and extended lows, are reviewed. The pulse period decreases irregularly. The pulsed fraction (2-7 keV) is 70%-90% for single pulses but significantly less for superpositions of pulses, due to variability in shape. The pulses are narrower at higher energies with a correlated increase in fraction pulsed. The orbital period is found to both decrease and increase with p/p on the order of a few times 0.00001/year. A three sigma upper limit on the eccentricity of 0.003 is obtained; if no significant periastron motion is allowed over two years, the upper limit becomes 0.0016. The orbital period is found to be detectable during some extended lows but with a significantly decreased ratio of eclipsed to non-eclipsed intensity. Two transitions between normal high states and extended lows are studied, and a consistent model is obtained in which extended lows are caused by both burying the source in an increased stellar wind from the companion, and starving the source by decreasing the stellar wind. Changes in fraction pulsed during transitions and systematic differences in the harmonic content of the pulses are also found.

Orbital evolution of small binary asteroids

NASA Astrophysics Data System (ADS)

Ćuk, Matija; Nesvorný, David

2010-06-01

About 15% of both near-Earth and main-belt asteroids with diameters below 10 km are now known to be binary. These small asteroid binaries are relatively uniform and typically contain a fast-spinning, flattened primary and a synchronously rotating, elongated secondary that is 20-40% as large (in diameter) as the primary. The principal formation mechanism for these binaries is now thought to be YORP (Yarkovsky-O'Keefe-Radzievskii-Paddack) effect induced spin-up of the primary followed by mass loss and accretion of the secondary from the released material. It has previously been suggested (Ćuk, M. [2007]. Astrophys. J. 659, L57-L60) that the present population of small binary asteroids is in a steady state between production through YORP and destruction through binary YORP (BYORP), which should increase or decrease secondary's orbit, depending on the satellite's shape. However, BYORP-driven evolution has not been directly modeled until now. Here we construct a simple numerical model of the binary's orbital as well the secondary's rotational dynamics which includes BYORP and selected terms representing main solar perturbations. We find that many secondaries should be vulnerable to chaotic rotation even for relatively low-eccentricity mutual orbits. We also find that the precession of the mutual orbit for typical small binary asteroids might be dominated by the perturbations from the prolate and librating secondary, rather than the oblate primary. When we evolve the mutual orbit by BYORP we find that the indirect effects on the binary's eccentricity (through the coupling between the orbit and the secondary's spin) dominate over direct ones caused by the BYORP acceleration. In particular, outward evolution causes eccentricity to increase and eventually triggers chaotic rotation of the secondary. We conclude that the most likely outcome will be reestablishing of the synchronous lock with a "flipped" secondary which would then evolve back in. For inward evolution we find an initial decrease of eccentricity and secondary's librations, to be followed by later increase. We think that it is likely that various forms of dissipation we did not model may damp the secondary's librations close to the primary, allowing for further inward evolution and a possible merger. We conclude that a merger or a tidal disruption of the secondary are the most likely outcomes of the BYORP evolution. Dissociation into heliocentric pairs by BYORP alone should be very difficult, and satellite loss might be restricted to the minority of systems containing more than one satellite at the time.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yagi, Kent; Tanaka, Takahiro; Yukawa Institute for Theoretical Physics, Kyoto University, Kyoto 606-8502

We calculate how strongly one can put constraints on alternative theories of gravity such as Brans-Dicke and massive graviton theories with LISA. We consider inspiral gravitational waves from a compact binary composed of a neutron star and an intermediate mass black hole in Brans-Dicke (BD) theory and that composed of a super massive black hole in massive graviton theories. We use the restricted second post-Newtonian waveforms including the effects of spins. We also take both precession and eccentricity of the orbit into account. For simplicity, we set the fiducial value for the spin of one of the binary constituents tomore » zero so that we can apply the approximation called simple precession. We perform the Monte Carlo simulations of 10{sup 4} binaries, estimating the determination accuracy of binary parameters including the BD parameter {omega}{sub BD} and the Compton wavelength of graviton {lambda}{sub g} for each binary using the Fisher matrix method. We find that including both the spin-spin coupling {sigma} and the eccentricity e into the binary parameters reduces the determination accuracy by an order of magnitude for the Brans-Dicke case, while it has less influence on massive graviton theories. On the other hand, including precession enhances the constraint on {omega}{sub BD} only 20% but it increases the constraint on {lambda}{sub g} by several factors. Using a (1.4+1000)M{sub {center_dot}}neutron star/black hole binary of SNR={radical}(200), one can put a constraint {omega}{sub BD}>6944, while using a (10{sup 7}+10{sup 6})M{sub {center_dot}}black hole/black hole binary at 3 Gpc, one can put {lambda}{sub g}>3.10x10{sup 21} cm, on average. The latter is 4 orders of magnitude stronger than the one obtained from the solar system experiment. These results are consistent with previous results within uncontrolled errors and indicate that the effects of precession and eccentricity must be taken carefully in the parameter estimation analysis.« less

Period Variations of the Eclipsing Binary Systems T LMi and VX Lac

NASA Astrophysics Data System (ADS)

Yılmaz, M.; İzci, D. D.; Gümüş, D.; Özavci, İ.; Selam, S. O.

2015-07-01

We present a period analysis of the two Algol-type eclipsing binary systems T LMi and VX Lac using all available times of minimum in the literature, as well as new minima obtained at the Ankara University Kreiken Observatory. The period analysis of T LMi suggests mass transfer between the components and also a third body that is dynamically bound to the binary system. The analysis of VX Lac also suggests mass transfer between the components, and the presence of a third and a fourth body under the assumption of a Light-Time Effect. In addition, the periodic variation of VX Lac was examined under the hypothesis of magnetic activity, and the corresponding parameters were derived. We report here the orbital parameters for both systems, along with the ones related to mass transfer, and those for the third and fourth bodies.

Kottamia 74-inch telescope discovery of the new eclipsing binary 2MASS J20004638 + 0547475.: First CCD photometry and light curve analysis

NASA Astrophysics Data System (ADS)

Darwish, M. S.; Shokry, A.; Saad, S. M.; El-Sadek, M. A.; Essam, A.; Ismail, M.

2017-05-01

A CCD photometric study is presented for the eclipsing binary system 2MASS J20004638 + 0547475. Observations of the system were obtained in the V, R and I colours with the 2Kx2K CCD attached to 1.88 m Kottamia Optical Telescope. New times of light minimum and new ephemeris were obtained. The V, R and I light curves were analyzed using the PHOEBE 0.31 program to determine geometrical and physical parameters of the system. The results show that 2MASS J20004638 + 0547475, is A-Type WUMa and is an overcontact binary with high fill-out factor = 69%. The current evolutionary status of the system indicates that the primary component lies very close to the main sequence while the secondary is evolved. The asymmetric maxima were studied and a modeling of the hot spot parameters is given.

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

NASA Astrophysics Data System (ADS)

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.

Photometric study of two eclipsing binary stars: Light curve analysis and system parameters for GU CMa and SWASP J011732.10+525204.9

NASA Astrophysics Data System (ADS)

Shokry, A.; Saad, S. M.; Hamdy, M. A.; Beheary, M. M.; Abolazm, M. S.; Gadallah, K. A.; El-Depsey, M. H.; Al-Gazzar, M. S.

2018-02-01

A new photometric study of two eclipsing binary systems (GU CMa and SWASP J011732.10+525204.9) is presented. The accepted solutions of analyzing the light curves revealed that GU CMa is a semi-detached system consisting of two early spectral type components, (B2 and B2.5) while SWASP J011732.10+525204.9 is a contact binary with two late type components (K2 and M1). The primary component of each system is the massive one. The geometric configuration indicates that SWASP J011732.10+525204.9 passes through a very critical phase in which each component exactly fills its limited lobe with zero fill out ratio. New times of minimum and the absolute physical parameters for each system are determined. The evolution status for each system has been investigated.

A possible third component in the eclipsing binary system HS 2231+2441

NASA Astrophysics Data System (ADS)

Vidmachenko, A. P.; Romanyuk, Ya. O.; Shliahetskaya, Ya. O.

2016-05-01

We used a differential photometry method in which we compared the flow of program star and standard one. Observations of the 21 nights in the period from July 26 to December 2, 2015 are used for processing. The accuracy of determining for each measurement is in the range 0,003...0,009 m for different nights. On the basis of obtained data were created corresponding light curves. Next, we calculate the time difference between the centers of transits. Its time dependence showed the presence of a possible periodic change in the deflection of the middle transit time from the calculated average value. This may indicate the presence of a third object in the eclipsing binary system. It has been found that the periodic variation of the orbital period can be explained by the gravitational influence of a third companion on the central binary system with an orbital period of about 97±10 d.

Light Curve and Analysis of the Eclipsing Binary BF Centauri

NASA Astrophysics Data System (ADS)

Morris, M. A.; Wolf, G. W.

2003-12-01

The eclipsing binary star BF Centauri was observed photometrically by GWW in the uvby filter system from Mt. John Observatory in New Zealand during 1982, 1989 and 1998. It was also observed spectroscopically at 10 A/mm by W. A. Lawson in 1993 at Mt. Stromlo in Australia to obtain a radial velocity solution. The combined light curves and spectroscopic results have been analyzed using the 1998 version of Robert Wilson's WD light-curve programs. A consistent model for the system will be presented. This analysis was done as a part of a senior research project by MAM, who would like to acknowledge financial support from the Missouri Space Grant Consortium.

Timing of millisecond pulsars in globular clusters

NASA Astrophysics Data System (ADS)

D'Amico, Nichi; Possenti, Andrea; Manchester, Dick; Johnston, Simon; Kramer, Michael; Sarkissian, John; Lyne, Andrew; Burgay, Marta; Corongiu, Alessandro; Camilo, Fernando; Bailes, Matthew; van Straten, Willem

2014-10-01

Timing of the dozen pulsars discovered by us in P303 is ensuring high quality results: (a) the peculiarities (in position or projected acceleration) of all the 5 millisecond pulsars in NGC6752 suggested the presence of non thermal dynamics in the core, perhaps due to black-holes of intermediate mass; (b) the eclipsing pulsar in NGC6397 is a stereotype for studying the late evolution of exotic binaries. We propose to continue our timing project focusing mostly on NGC6397 at 10cm, for studying the orbital secular evolution, the eclipse region, and the role played by the high energy photons released from the pulsar in the ejection of matter from the binary system.

Photometric Follow-up of Eclipsing Binary Candidates from KELT and Kepler

NASA Astrophysics Data System (ADS)

Garcia Soto, Aylin; Rodriguez, Joseph E.; Bieryla, Allyson; KELT survey

2018-01-01

Eclipsing binaries (EBs) are incredibly valuable, as they provide the opportunity to precisely measure fundamental stellar parameters without the need for stellar models. Therefore, we can use EBs to directly test stellar evolution models. Constraining the stellar properties of stars is important since they directly influence our understanding of any planets orbiting them. Using the Harvard University's Clay 0.4m telescope and Fred Lawrence Whipple Observatory’s 1.2m telescope on Mount Hopkins, Arizona, we conducted follow-up multi-band photometric observations of EB candidates from the Kilodegree Extremely Little Telescope (KELT) survey and the Kepler mission. We will present our follow-up observations and AstroImageJ analysis on these 5 EB systems.

Eccentricity in planetary systems and the role of binarity. Sample definition, initial results, and the system of HD 211847

NASA Astrophysics Data System (ADS)

Moutou, C.; Vigan, A.; Mesa, D.; Desidera, S.; Thébault, P.; Zurlo, A.; Salter, G.

2017-06-01

We explore the multiplicity of exoplanet host stars with high-resolution images obtained with VLT/SPHERE. Two different samples of systems were observed: one containing low-eccentricity outer planets, and the other containing high-eccentricity outer planets. We find that 10 out of 34 stars in the high-eccentricity systems are members of a binary, while the proportion is 3 out of 27 for circular systems. Eccentric-exoplanet hosts are, therefore, significantly more likely to have a stellar companion than circular-exoplanet hosts. The median magnitude contrast over the 68 data sets is 11.26 and 9.25, in H and K, respectively, at 0.30 arcsec. The derived detection limits reveal that binaries with separations of less than 50 au are rarer for exoplanet hosts than for field stars. Our results also imply that the majority of high-eccentricity planets are not embedded in multiple stellar systems (24 out of 34), since our detection limits exclude the presence of a stellar companion. We detect the low-mass stellar companions of HD 7449 and HD 211847, both members of our high-eccentricity sample. HD 7449B was already detected and our independent observation is in agreement with this earlier work. HD 211847's substellar companion, previously detected by the radial velocity method, is actually a low-mass star seen face-on. The role of stellar multiplicity in shaping planetary systems is confirmed by this work, although it does not appear as the only source of dynamical excitation. Based on observations collected with SPHERE on the Very Large Telescope (ESO, Chile).

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tokovinin, Andrei, E-mail: atokovinin@ctio.noao.edu

Radial velocity (RV) monitoring of solar-type visual binaries has been conducted at the CTIO/SMARTS 1.5 m telescope to study short-period systems. The data reduction is described, and mean and individual RVs of 163 observed objects are given. New spectroscopic binaries are discovered or suspected in 17 objects, and for some of them the orbital periods could be determined. Subsystems are efficiently detected even in a single observation by double lines and/or by the RV difference between the components of visual binaries. The potential of this detection technique is quantified by simulation and used for statistical assessment of 96 wide binariesmore » within 67 pc. It is found that 43 binaries contain at least one subsystem, and the occurrence of subsystems is equally probable in either primary or secondary components. The frequency of subsystems and their periods matches the simple prescription proposed by the author. The remaining 53 simple wide binaries with a median projected separation of 1300 AU have an RV difference distribution between their components that is not compatible with the thermal eccentricity distribution f (e) = 2e but rather matches the uniform eccentricity distribution.« less

A spectroscopic binary in the Hercules dwarf spheroidal galaxy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Koch, Andreas; Hansen, Terese; Feltzing, Sofia

2014-01-01

We present the radial velocity curve of a single-lined spectroscopic binary in the faint Hercules dwarf spheroidal (dSph) galaxy, based on 34 individual spectra covering more than 2 yr of observations. This is the first time that orbital elements could be derived for a binary in a dSph. The system consists of a metal-poor red giant and a low-mass companion, possibly a white dwarf, with a 135 day period in a moderately eccentric (e = 0.18) orbit. Its period and eccentricity are fully consistent with metal-poor binaries in the Galactic halo, while the projected semimajor axis is small, at a{submore » p} sin i = 38 R {sub ☉}. In fact, a very close orbit could inhibit the production of heavier elements through s-process nucleosynthesis, leading to the very low abundances of neutron-capture elements that are found in this star. We discuss the further implications for the chemical enrichment history of the Hercules dSph, but find no compelling binary scenario that could reasonably explain the full, peculiar abundance pattern of the Hercules dSph galaxy.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, Xian; Amaro-Seoane, Pau, E-mail: xian.chen@pku.edu.cn, E-mail: pau@ice.cat

The formation of compact stellar-mass binaries is a difficult, but interesting problem in astrophysics. There are two main formation channels: in the field via binary star evolution, or in dense stellar systems via dynamical interactions. The Laser Interferometer Gravitational-wave Observatory (LIGO) has detected black hole binaries (BHBs) via their gravitational radiation. These detections provide us with information about the physical parameters of the system. It has been claimed that when the Laser Interferometer Space Antenna (LISA) is operating, the joint observation of these binaries with LIGO will allow us to derive the channels that lead to their formation. However, wemore » show that for BHBs in dense stellar systems dynamical interactions could lead to high eccentricities such that a fraction of the relativistic mergers are not audible to LISA. A non-detection by LISA puts a lower limit of about 0.005 on the eccentricity of a BHB entering the LIGO band. On the other hand, a deci-Hertz observatory, like DECIGO or Tian Qin, would significantly enhance the chances of a joint detection and shed light on the formation channels of these binaries.« less

Dayside atmospheric structure of HD209458b from Spitzer eclipses

NASA Astrophysics Data System (ADS)

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.

Worldwide photometry of the January 1989 Tau Persei eclipse

NASA Technical Reports Server (NTRS)

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.

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

NASA Astrophysics Data System (ADS)

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.

Time-resolved spectroscopy and photometry of the eclipsing AM Herculis binary EXO 033319 - 2554.2

NASA Technical Reports Server (NTRS)

Allen, Richard G.; Berriman, Graham; Smith, Paul S.; Schmidt, Gary D.

1989-01-01

Time-resolved optical observations of the eclipsing AM Herculis binary EXO 033319 - 2554.2 are presented. High-speed photometry of an eclipse is presented and used to derive a new ephemeris for the system and to estimate the size of the region responsible for the cyclotron emission. Optical spectra that span the orbital cycle are presented, the cyclotron emission in these spectra is discussed, and the flux and radial velocity variations of H-beta, H-gamma, and He II 4686 A are examined. Models of the flux and radial velocity variations of the emission lines indicate that about half the line emission comes from low-velocity material that is about 1.4 x 10 to the 10th cm from the white dwarf. The rest comes from high-velocity material that is about 10 to the 10th cm from the white dwarf and is moving toward it at about 600 km/s.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gong, Yan-Xiang, E-mail: yxgong@sina.com

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

VizieR Online Data Catalog: Orbital parameters of 341 new binaries (Murphy+, 2018)

NASA Astrophysics Data System (ADS)

Murphy, S. J.; Moe, M.; Kurtz, D. W.; Bedding, T.; Shibahashi, H.; Boffin, H. M. J.

2018-01-01

Kepler targets with effective temperatures between 6600 and 10000K have been investigated for pulsational phase modulation that can be attributed to binary orbital motion. For each target, we provide a binary status, which also reflects whether or not the target pulsates. For the binary systems, we provide the Kepler Input Catalogue (KIC) number, as well as the binary orbital elements: the period, semi-major axis, eccentricity, longitude of periastron, time of periastron passage, binary mass function and a calculated radial velocity semi-amplitude. (3 data files).

Discovery of two eclipsing X-ray binaries in M 51

NASA Astrophysics Data System (ADS)

Wang, Song; Soria, Roberto; Urquhart, Ryan; Liu, Jifeng

2018-04-01

We discovered eclipses and dips in two luminous (and highly variable) X-ray sources in M 51. One (CXOM51 J132943.3+471135) is an ultraluminous supersoft source, with a thermal spectrum at a temperature of about 0.1 keV and characteristic blackbody radius of about 104 km. The other (CXOM51 J132946.1+471042) has a two-component spectrum with additional thermal-plasma emission; it approached an X-ray luminosity of 1039erg s-1 during outbursts in 2005 and 2012. From the timing of three eclipses in a series of Chandra observations, we determine the binary period (52.75 ± 0.63 hr) and eclipse fraction (22% ± 0.1%) of CXOM51 J132946.1+471042. We also identify a blue optical counterpart in archival Hubble Space Telescope images, consistent with a massive donor star (mass of ˜20-35M⊙). By combining the X-ray lightcurve parameters with the optical constraints on the donor star, we show that the mass ratio in the system must be M_2/M_1 ≳ 18, and therefore the compact object is most likely a neutron star (exceeding its Eddington limit in outburst). The general significance of our result is that we illustrate one method (applicable to high-inclination sources) of identifying luminous neutron star X-ray binaries, in the absence of X-ray pulsations or phase-resolved optical spectroscopy. Finally, we discuss the different X-ray spectral appearance expected from super-Eddington neutron stars and black holes at high viewing angles.

EC 10246-2707: an eclipsing subdwarf B + M dwarf binary

NASA Astrophysics Data System (ADS)

Barlow, B. N.; Kilkenny, D.; Drechsel, H.; Dunlap, B. H.; O'Donoghue, D.; Geier, S.; O'Steen, R. G.; Clemens, J. C.; LaCluyze, A. P.; Reichart, D. E.; Haislip, J. B.; Nysewander, M. C.; Ivarsen, K. M.

2013-03-01

We announce the discovery of a new eclipsing hot subdwarf B + M dwarf binary, EC 10246-2707, and present multicolour photometric and spectroscopic observations of this system. Similar to other HW Vir-type binaries, the light curve shows both primary and secondary eclipses, along with a strong reflection effect from the M dwarf; no intrinsic light contribution is detected from the cool companion. The orbital period is 0.118 507 9936 ± 0.000 000 0009 d, or about 3 h. Analysis of our time series spectroscopy reveals a velocity semi-amplitude of K1 = 71.6 ± 1.7 km s-1 for the sdB and best-fitting atmospheric parameters of Teff = 28 900 ± 500 K, log g = 5.64 ± 0.06 and log N(He)/N(H) = -2.5 ± 0.2. Although we cannot claim a unique solution from modelling the light curve, the best-fitting model has an sdB mass of 0.45 M⊙ and a cool companion mass of 0.12 M⊙. These results are roughly consistent with a canonical-mass sdB and M dwarf separated by a ˜ 0.84 R⊙. We find no evidence of pulsations in the light curve and limit the amplitude of rapid photometric oscillations to <0.08 per cent. Using 15 yr of eclipse timings, we construct an observed minus calculated (O - C) diagram but find no statistically significant period changes; we rule out |dot{P}| > 7.2 × 10^{-12}. If EC 10246-2707 evolves into a cataclysmic variable, its period should fall below the famous cataclysmic variable period gap.

Discovery of two eclipsing X-ray binaries in M 51

NASA Astrophysics Data System (ADS)

Wang, Song; Soria, Roberto; Urquhart, Ryan; Liu, Jifeng

2018-07-01

We discovered eclipses and dips in two luminous (and highly variable) X-ray sources in M 51. One (CXOM51 J132943.3+471135) is an ultraluminous supersoft source, with a thermal spectrum at a temperature of about 0.1 keV and characteristic blackbody radius of about 104 km. The other (CXOM51 J132946.1+471042) has a two-component spectrum with additional thermal-plasma emission; it approached an X-ray luminosity of 1039 erg s-1 during outbursts in 2005 and 2012. From the timing of three eclipses in a series of Chandra observations, we determine the binary period (52.75 ± 0.63 h) and eclipse fraction (22 ± 0.1 per cent) of CXOM51 J132946.1+471042. We also identify a blue optical counterpart in archival Hubble Space Telescope images, consistent with a massive donor star (mass of ˜20-35 M⊙). By combining the X-ray light-curve parameters with the optical constraints on the donor star, we show that the mass ratio in the system must be M_2/M_1 ≳ 18 and therefore the compact object is most likely a neutron star (exceeding its Eddington limit in outburst). The general significance of our result is that we illustrate one method (applicable to high-inclination sources) of identifying luminous neutron star X-ray binaries, in the absence of X-ray pulsations or phase-resolved optical spectroscopy. Finally, we discuss the different X-ray spectral appearance expected from super-Eddington neutron stars and black holes at high viewing angles.

Further studies on criteria for the onset of dynamical instability in general three-body systems

NASA Technical Reports Server (NTRS)

Pendleton, Y. J.; Black, D. C.

1983-01-01

Numerical experiments designed for the elucidation of the conditions under which self-gravitating, three-body systems become dynamically unstable are examined of the cases of four orbital configuration types: circular, prograde, and coplanar; circular, retrograde, and coplanar; circular, direct, and inclined; and eccentric, direct, and coplanar. Results indicate that orbital inclination does not significantly affect stability in 'outer planet' configurations, while the stability of 'inner planet' configurations, where the tertiary is in close orbit about one member of the binary, is markedly less affected, once the relative orbital inclination is greater than 50 deg. It is found that the onset of dynamical instability is only weakly dependent on the eccentricity of either the binary or tertiary orbit, as long as the mass of the tertiary is comparable to the reduced mass of the binary.

Astronomy in Denver: Spectropolarimetric Observations of 5 Wolf-Rayet Binary Stars with SALT/RSS

NASA Astrophysics Data System (ADS)

Fullard, Andrew; Ansary, Zyed; Azancot Luchtan, Daniel; Gallegos, Hunter; Luepker, Martin; Hoffman, Jennifer L.; Nordsieck, Kenneth H.; SALT observation team

2018-06-01

Mass loss from massive stars is an important yet poorly understood factor in shaping their evolution. Wolf-Rayet (WR) stars are of particular interest due to their stellar winds, which create large regions of circumstellar material (CSM). They are also supernova and possible gamma-ray burst (GRB) progenitors. Like other massive stars, WR stars often occur in binaries, where interaction can affect their mass loss rates and provide the rapid rotation thought to be required for GRB production. The diagnostic tool of spectropolarimetry, along with the potentially eclipsing nature of a binary system, helps us to better characterize the CSM created by the stars’ colliding winds. Thus, we can determine mass loss rates and infer rapid rotation. We present spectropolarimetric results for five WR+O eclipsing binary systems, obtained with the Robert Stobie Spectrograph at the South African Large Telescope, between April 2017 and April 2018. The data allow us to map both continuum and emission line polarization variations with phase, which constrains where different CSM components scatter light in the systems. We discuss our initial findings and interpretations of the polarimetric variability in each binary system, and compare the systems.

Tapir: A web interface for transit/eclipse observability

NASA Astrophysics Data System (ADS)

Jensen, Eric

2013-06-01

Tapir is a set of tools, written in Perl, that provides a web interface for showing the observability of periodic astronomical events, such as exoplanet transits or eclipsing binaries. The package provides tools for creating finding charts for each target and airmass plots for each event. The code can access target lists that are stored on-line in a Google spreadsheet or in a local text file.

THE KOZAI–LIDOV MECHANISM IN HYDRODYNAMICAL DISKS. II. EFFECTS OF BINARY AND DISK PARAMETERS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fu, Wen; Lubow, Stephen H.; Martin, Rebecca G., E-mail: wf5@rice.edu

2015-07-01

Martin et al. showed that a substantially misaligned accretion disk around one component of a binary system can undergo global damped Kozai–Lidov (KL) oscillations. During these oscillations, the inclination and eccentricity of the disk are periodically exchanged. However, the robustness of this mechanism and its dependence on the system parameters were unexplored. In this paper, we use three-dimensional hydrodynamical simulations to analyze how various binary and disk parameters affect the KL mechanism in hydrodynamical disks. The simulations include the effect of gas pressure and viscosity, but ignore the effects of disk self-gravity. We describe results for different numerical resolutions, binarymore » mass ratios and orbital eccentricities, initial disk sizes, initial disk surface density profiles, disk sound speeds, and disk viscosities. We show that the KL mechanism can operate for a wide range of binary-disk parameters. We discuss the applications of our results to astrophysical disks in various accreting systems.« less

V850 Cyg: An eclipsing binary with a giant γ Dor pulsator

NASA Astrophysics Data System (ADS)

Çakırlı, Ö.; Ibanoglu, C.; Sipahi, E.; Akan, M. C.

2017-04-01

We present new spectroscopic observations of the double-lined eclipsing binary V850 Cyg. The long-cadence photometric observations obtained by Kepler were analysed and combined with the analysis of radial velocities for deriving the absolute parameters of the components. Masses and radii were determined as Mp=1.601 ± 0.076 M⊙ and Rp=4.239 ± 0.076 R⊙, Ms=0.851 ± 0.053 M⊙ and Rs=5.054 ± 0.087 R⊙ for the components of V850 Cyg. We estimate an interstellar reddening of 0.28 ± 0.12 mag and a distance of 1040 ± 160 pc for the system. The measured rotational velocity of the secondary appears to lower than that of synchronize rotation. However its spectral lines are too weak to be measured the rotational velocity with reasonable accuracy. We have extracted the synthetic light curve from the observations and excluded the data within the eclipses for the frequency analysis. We obtained at least nine frequencies in the γ Dor regime. It seems that the primary component oscillates with a dominant period of about 1.152549 ± 0.000009 days. We also compare pulsational properties of the primary star of V850 Cyg with the γ Dor type pulsating components in other binaries.

On a possible additional component in an eclipsing binary system HS 2231 + 2441

NASA Astrophysics Data System (ADS)

Vidmachenko, A. P.; Romanyuk, Ya. O.; Shliahetskaya, Ya. O.

2016-05-01

Timing method based on the registration period of variations of a periodic process, associated with the star. The study of stellar eclipsing binary system for a long time allows a series of several transits, depending on the orbital period of the satellite smaller. We present a photometric study of system of the type HW Vir HS 2231 + 2441. Photometric data processing was performed using C-MuniWin Version 1.2.30 program. The accuracy of values for each observation point is in the range 0,003...0,009m for different nights. The calculated ephemeris determined from the light curve by fitting of arc of minimums to the nuclei of primary and secondary eclipses. The amplitude of the periodic changes of minimums moments that arise from the orbital motion of a close pair of stars around the barycenter of the triple system, is less than 0.0008 days (1.15 minutes). It was found that the periodic variation of the orbital period can be explained by the gravitational influence of a third companion on the central binary system with an orbital period of about 97±10d. Periodogram analysis of the observational data series indicate also on the periodicity with values of 48±5d and 195±15d, but with substantially less reliably

Dramatic Evolution of the Disk-shaped Secondary in the Orion Trapezium Star θ1 Ori B1 (BM Ori): MOST Satellite Observations

NASA Astrophysics Data System (ADS)

Windemuth, Diana; Herbst, William; Tingle, Evan; Fuechsl, Rachel; Kilgard, Roy; Pinette, Melanie; Templeton, Matthew; Henden, Arne

2013-05-01

The eclipsing binary θ1 Orionis B1, variable star designation BM Ori, is the faintest of the four well-known Trapezium stars at the heart of the Orion Nebula. The primary is a B3 star (~6 M ⊙) but the nature of the secondary (~2 M ⊙) has long been mysterious, since the duration and shape of primary eclipse are inappropriate for any sort of ordinary star. Here we report nearly continuous photometric observations obtained with the MOST satellite over ~4 cycles of the 6.47 d binary period. The light curve is of unprecedented quality, revealing a deep, symmetric primary eclipse as well as a clear reflection effect and secondary eclipse. In addition, there are other small disturbances, some of which repeat at the same phase over the four cycles monitored. The shape of the primary light curve has clearly evolved significantly over the past 40 years. While its overall duration and depth have remained roughly constant, the slopes of the descent and ascent phases are significantly shallower now than in the past and its distinctive flat-bottomed "pseudo-totality" is much less obvious or even absent in the most recent data. We further demonstrate that the primary eclipse was detected at X-ray wavelengths during the Chandra Orion Ultradeep Project (COUP) study. The light curve continues to be well modeled by a self-luminous and reflective disk-shaped object seen nearly edge-on orbiting the B3 primary. The dramatic change in shape over four decades is modeled as an opacity variation in a tenuous outer envelope or disk of the secondary object. We presume that the secondary is an extremely young protostar at an earlier evolutionary phase than can be commonly observed elsewhere in the Galaxy and that the opacity variations observed are related to its digestion of some accreted matter over the last 50-100 years. Indeed, this object deserves continued observational and theoretical attention as the youngest known eclipsing binary system.

DRAMATIC EVOLUTION OF THE DISK-SHAPED SECONDARY IN THE ORION TRAPEZIUM STAR {theta}{sup 1} Ori B{sub 1} (BM Ori): MOST SATELLITE OBSERVATIONS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Windemuth, Diana; Herbst, William; Tingle, Evan

2013-05-01

The eclipsing binary {theta}{sup 1} Orionis B{sub 1}, variable star designation BM Ori, is the faintest of the four well-known Trapezium stars at the heart of the Orion Nebula. The primary is a B3 star ({approx}6 M{sub Sun }) but the nature of the secondary ({approx}2 M{sub Sun }) has long been mysterious, since the duration and shape of primary eclipse are inappropriate for any sort of ordinary star. Here we report nearly continuous photometric observations obtained with the MOST satellite over {approx}4 cycles of the 6.47 d binary period. The light curve is of unprecedented quality, revealing a deep,more » symmetric primary eclipse as well as a clear reflection effect and secondary eclipse. In addition, there are other small disturbances, some of which repeat at the same phase over the four cycles monitored. The shape of the primary light curve has clearly evolved significantly over the past 40 years. While its overall duration and depth have remained roughly constant, the slopes of the descent and ascent phases are significantly shallower now than in the past and its distinctive flat-bottomed ''pseudo-totality'' is much less obvious or even absent in the most recent data. We further demonstrate that the primary eclipse was detected at X-ray wavelengths during the Chandra Orion Ultradeep Project (COUP) study. The light curve continues to be well modeled by a self-luminous and reflective disk-shaped object seen nearly edge-on orbiting the B3 primary. The dramatic change in shape over four decades is modeled as an opacity variation in a tenuous outer envelope or disk of the secondary object. We presume that the secondary is an extremely young protostar at an earlier evolutionary phase than can be commonly observed elsewhere in the Galaxy and that the opacity variations observed are related to its digestion of some accreted matter over the last 50-100 years. Indeed, this object deserves continued observational and theoretical attention as the youngest known eclipsing binary system.« less

ON THE LIKELIHOOD OF PLANET FORMATION IN CLOSE BINARIES

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jang-Condell, Hannah, E-mail: hjangcon@uwyo.edu

2015-02-01

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

BIRTH LOCATIONS OF THE KEPLER CIRCUMBINARY PLANETS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Silsbee, Kedron; Rafikov, Roman R., E-mail: ksilsbee@astro.princeton.edu

2015-07-20

The Kepler mission has discovered about a dozen circumbinary planetary systems, all containing planets on ∼1 AU orbits. We place bounds on the locations in the circumbinary protoplanetary disk, where these planets could have formed through collisional agglomeration starting from small (kilometer-sized or less) planetesimals. We first present a model of secular planetesimal dynamics that accounts for the (1) perturbation due to the eccentric precessing binary, as well as the (2) gravity and (3) gas drag from a precessing eccentric disk. Their simultaneous action leads to rich dynamics, with (multiple) secular resonances emerging in the disk. We derive analytic resultsmore » for size-dependent planetesimal eccentricity and demonstrate the key role of the disk gravity for circumbinary dynamics. We then combine these results with a simple model for collisional outcomes and find that in systems like Kepler-16, planetesimal growth starting with 10–100 m planetesimals is possible outside a few AU. The exact location exterior to which this happens is sensitive to disk eccentricity, density, and precession rate, as well as to the size of the first generation of planetesimals. Strong perturbations from the binary in the inner part of the disk, combined with a secular resonance at a few AU, inhibit the growth of kilometer-sized planetesimals within 2–4 AU of the binary. In situ planetesimal growth in the Kepler circumbinary systems is possible only starting from large initial planetesimals (few-kilometer-sized even assuming favorable disk properties, i.e., low surface density)« less

First Precision Photometric Observations and Analyses of The Totally Eclipsing, Solar Type Binary, V573 Pegasi

NASA Astrophysics Data System (ADS)

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

2018-06-01

CCD, VRI light curves of V573 Peg were taken in 26,27 September and 2, 4 and 6 October, 2017 at the Dark Sky Observatory in North Carolina with the 0.81-m reflector of Appalachian State University by D. Caton. V573 Peg was discovered by the SAVS survey which classified it as a V= 0.51 amplitude, EW variable. They included a rough spectrum identifying the binary was about a type G, although the period would indicate it is an F-type contact binary. Five times of minimum light were calculated, two primary eclipses and three secondary, from our present observations:HJD I = 2458023.6420±0.0012, 2458028.6522±0.0021,HJD II = 2458022.5991±0.0011, 2458023.8510±0.0010 and 2458028.8608±0.0005,The following linear and quadratic ephemerides were determined from all available times of minimum light.JD Hel MinI = 2456876.49437±0.00078d + 0.41745021±0. 00000017 × E, -JD Hel MinI = 2456876.49580±0.00023d + 0. 417448601±0.000000083× E - 0.000000000274±0.000000000012 X E2A 14-year period study (24 times of minimum light) revealed that the orbital period decreasing with a high level of confidence, possibly due to magnetic braking. The mass ratio is found to be somewhat extreme, M2/M1=0.2629±0.0006.Its Roche Lobe fill-out is 25%. The solution had no need of spots. The temperature difference of the components is about ~130 K, with the secondary as the hotter star, so it is a W-type W UMa Binary. The inclination is 80.4±0.1° . The secondary eclipse shows a time of constant light with an eclipse duration of 24 minutes. More details of our results will be given at the meeting.

Discovery of a Detached, Eclipsing 40 Minute Period Double White Dwarf Binary and a Friend: Implications for He+CO White Dwarf Mergers

NASA Astrophysics Data System (ADS)

Brown, Warren R.; Kilic, Mukremin; Kosakowski, Alekzander; Gianninas, A.

2017-09-01

We report the discovery of two detached double white dwarf (WD) binaries, SDSS J082239.546+304857.19 and SDSS J104336.275+055149.90, with orbital periods of 40 and 46 minutes, respectively. The 40 minute system is eclipsing; it is composed of a 0.30 M ⊙ and a 0.52 M ⊙ WD. The 46 minute system is a likely LISA verification binary. The short 20 ± 2 Myr and ˜34 Myr gravitational-wave merger times of the two binaries imply that many more such systems have formed and merged over the age of the Milky Way. We update the estimated Milky Way He+CO WD binary merger rate and affirm our previously published result: He+CO WD binaries merge at a rate at least 40 times greater than the formation rate of stable mass-transfer AM CVn binaries, and so the majority must have unstable mass-transfer. The implication is that spin-orbit coupling in He+CO WD mergers is weak, or perhaps nova-like outbursts drive He+CO WDs into merger, as proposed by Shen. Based on observations obtained at the MMT Observatory, a joint facility of the Smithsonian Institution and the University of Arizona, and on observations obtained with the Apache Point Observatory 3.5 m telescope, which is owned and operated by the Astrophysical Research Consortium.

High Fill-out, Extreme Mass Ratio Overcontact Binary Systems. X. The Newly Discovered Binary XY Leonis Minoris

NASA Astrophysics Data System (ADS)

Qian, S.-B.; Liu, L.; Zhu, L.-Y.; He, J.-J.; Yang, Y.-G.; Bernasconi, L.

2011-05-01

The newly discovered short-period close binary star, XY LMi, has been monitored photometrically since 2006. Its light curves are typical EW-type light curves and show complete eclipses with durations of about 80 minutes. Photometric solutions were determined through an analysis of the complete B, V, R, and I light curves using the 2003 version of the Wilson-Devinney code. XY LMi is a high fill-out, extreme mass ratio overcontact binary system with a mass ratio of q = 0.148 and a fill-out factor of f = 74.1%, suggesting that it is in the late evolutionary stage of late-type tidal-locked binary stars. As observed in other overcontact binary stars, evidence for the presence of two dark spots on both components is given. Based on our 19 epochs of eclipse times, we found that the orbital period of the overcontact binary is decreasing continuously at a rate of dP/dt = -1.67 × 10-7 days yr-1, which may be caused by mass transfer from the primary to the secondary and/or angular momentum loss via magnetic stellar wind. The decrease of the orbital period may result in the increase of the fill-out, and finally, it will evolve into a single rapid-rotation star when the fluid surface reaches the outer critical Roche lobe.

Ingress observations of the 1980 eclipse of the symbiotic star CI Cyngni

NASA Technical Reports Server (NTRS)

Stencel, R. E.; Michalitsianos, A. G.; Kafatos, M.; Boyarchuk, A. A.

1981-01-01

One of the major results from the IUE may prove to be the knowledge gained by studies of the ultraviolet spectra of symbiotic stars. Symbiotics combine spectral features of a cool M giant like photosphere with strong high excitation emission lines of nebular origin, superposed. The UV spectra are dominated by intense permitted and semiforbidden emission lines and weak continua indicative of hot compact objects and accretion disks. Two symbiotics, AR Pav and CI Cyg are thought to be eclipsing binaries and IUE observations during the 1980 eclipse of CI Cygni are discussed.

RR Lyrae stars in eclipsing systems -- historical candidates

NASA Astrophysics Data System (ADS)

Liška, J.; Skarka, M.; Hájková, P.; Auer, R. F.

2016-03-01

Discovery of binary systems among RR Lyrae stars belongs to challenges of present astronomy. So far, none of classical RR Lyrae stars was clearly confirmed, that it is a part of an eclipsing system. From this reason we studied two RR Lyrae stars, VX Her and RW Ari, in which changes assigned to eclipses were detected in sixties and seventies of the 20th century. In this paper our preliminary results based on analysis of new photometric measurements are presented as well as the results from the detailed analysis of original measurements. A new possible eclipsing system, RZ Cet was identified in the archive data. Our analysis rather indicates errors in measurements and reductions of the old data than real changes for all three stars.

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

NASA Astrophysics Data System (ADS)

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.

A POSSIBLE SIGNATURE OF LENSE-THIRRING PRECESSION IN DIPPING AND ECLIPSING NEUTRON-STAR LOW-MASS X-RAY BINARIES

DOE Office of Scientific and Technical Information (OSTI.GOV)

Homan, Jeroen, E-mail: jeroen@space.mit.edu

2012-12-01

Relativistic Lense-Thirring precession of a tilted inner accretion disk around a compact object has been proposed as a mechanism for low-frequency ({approx}0.01-70 Hz) quasi-periodic oscillations (QPOs) in the light curves of X-ray binaries. A substantial misalignment angle ({approx}15 Degree-Sign -20 Degree-Sign ) between the inner-disk rotation axis and the compact-object spin axis is required for the effects of this precession to produce observable modulations in the X-ray light curve. A consequence of this misalignment is that in high-inclination X-ray binaries the precessing inner disk will quasi-periodically intercept our line of sight to the compact object. In the case of neutron-starmore » systems, this should have a significant observational effect, since a large fraction of the accretion energy is released on or near the neutron-star surface. In this Letter, I suggest that this specific effect of Lense-Thirring precession may already have been observed as {approx}1 Hz QPOs in several dipping/eclipsing neutron-star X-ray binaries.« less

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Faigler, S.; Mazeh, T.; Tal-Or, L.

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 weremore » confirmed by spectroscopic RV follow-up observations, indicating minimum secondary masses in the range 0.07-0.4 M{sub Sun }. 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.« less

Can eccentric debris disks be long-lived?. A first numerical investigation and application to ζ2 Reticuli

NASA Astrophysics Data System (ADS)

Faramaz, V.; Beust, H.; Thébault, P.; Augereau, J.-C.; Bonsor, A.; del Burgo, C.; Ertel, S.; Marshall, J. P.; Milli, J.; Montesinos, B.; Mora, A.; Bryden, G.; Danchi, W.; Eiroa, C.; White, G. J.; Wolf, S.

2014-03-01

Context. Imaging of debris disks has found evidence for both eccentric and offset disks. One hypothesis is that they provide evidence for massive perturbers, for example, planets or binary companions, which sculpt the observed structures. One such disk was recently observed in the far-IR by the Herschel Space Observatory around ζ2 Reticuli. In contrast with previously reported systems, the disk is significantly eccentric, and the system is several Gyr old. Aims: We aim to investigate the long-term evolution of eccentric structures in debris disks caused by a perturber on an eccentric orbit around the star. We hypothesise that the observed eccentric disk around ζ2 Reticuli might be evidence of such a scenario. If so, we are able to constrain the mass and orbit of a potential perturber, either a giant planet or a binary companion. Methods: Analytical techniques were used to predict the effects of a perturber on a debris disk. Numerical N-body simulations were used to verify these results and further investigate the observable structures that may be produced by eccentric perturbers. The long-term evolution of the disk geometry was examined, with particular application to the ζ2 Reticuli system. In addition, synthetic images of the disk were produced for direct comparison with Herschel observations. Results: We show that an eccentric companion can produce both the observed offsets and eccentric disks. These effects are not immediate, and we characterise the timescale required for the disk to develop to an eccentric state (and any spirals to vanish). For ζ2 Reticuli, we derive limits on the mass and orbit of the companion required to produce the observations. Synthetic images show that the pattern observed around ζ2 Reticuli can be produced by an eccentric disk seen close to edge-on, and allow us to bring additional constraints on the disk parameters of our model (disk flux and extent). Conclusions: We conclude that eccentric planets or stellar companions can induce long-lived eccentric structures in debris disks. Observations of such eccentric structures thus provide potential evidence of the presence of such a companion in a planetary system. We considered the specific example of ζ2 Reticuli, whose observed eccentric disk can be explained by a distant companion (at tens of AU) on an eccentric orbit (ep ≳ 0.3). Appendices are available in electronic form at http://www.aanda.orgHerschel Space Observatory is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA.

An Atlas of Far-ultraviolet Spectra of the Zeta Aurigae Binary 31 Cygni with Line Identifications

NASA Astrophysics Data System (ADS)

Hagen Bauer, Wendy; Bennett, Philip D.

2014-04-01

The ζ Aurigae system 31 Cygni (K4 Ib + B4 V) was observed by the FUSE satellite during total eclipse and at three phases during chromospheric eclipse. We present the coadded, calibrated spectra and atlases with line identifications. During total eclipse, emission from high ionization states (e.g., Fe III and Cr III) shows asymmetric profiles redshifted from the systemic velocity, while emission from lower ionization states (e.g., Fe II and O I) appears more symmetric and is centered closer to the systemic velocity. Absorption from neutral and singly ionized elements is detected during chromospheric eclipse. Late in chromospheric eclipse, absorption from the K star wind is detected at a terminal velocity of ~80 km s-1. These atlases will be useful for interpreting the far-UV spectra of other ζ Aur systems, as the observed FUSE spectra of 32 Cyg, KQ Pup, and VV Cep during chromospheric eclipse resemble that of 31 Cyg.

Secondary eclipse observations and the atmosphere of exoplanet WASP-34b

NASA Astrophysics Data System (ADS)

Challener, Ryan C.; Harrington, Joseph; Cubillos, Patricio; Garland, Justin; Foster, Andrew S. D.; Blecic, Jasmina; Foster, AJ; Smalley, Barry

2015-11-01

WASP-34b is a short-period exoplanet with a mass of 0.59 ± 0.01 Jupiter masses orbiting a G5 star with a period of 4.3177 days and an eccentricity of 0.038 ± 0.012 (Smalley, 2010). We observed WASP-34b using the 3.6 and 4.5 μm channels of the Infrared Array Camera aboard the Spitzer Space Telescope in 2010 (Program 60003). We applied our Photometry for Orbits, Eclipses, and Transits (POET) code to present eclipse-depth measurements, estimates of infrared brightness temperatures, and a refined orbit. With our Bayesian Atmospheric Radiative Transfer (BART) code, we characterized the atmosphere's temperature and pressure profile, and molecular abundances. 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 NNX12AI69G and NASA Astrophysics Data Analysis Program grant NNX13AF38G. J. Blecic holds a NASA Earth and Space Science Fellowship.

WASP-12b: Orbital Decay or Apsidal Precession?

NASA Astrophysics Data System (ADS)

Winn, Joshua; Knutson, Heather

2018-05-01

Over the last decade, the interval between the transits of the hot Jupiter WASP-12b has been steadily shrinking by 29 milliseconds per year. This may represent the first direct detection of tidal orbital decay, a phenomenon that has long been predicted to occur for hot Jupiters and that features in many theories to explain their properties. Another viable explanation for the apparent period decrease is that the orbit is slightly eccentric and apsidally precessing, in which case the data could be used to measure the planet's Love number. This would be a rare and precious constraint on its interior density distribution. The best way to tell the difference is to combine new Spitzer observations of secondary eclipses with ongoing ground-based transit observations. Orbital decay predicts that the transit and eclipse timing residuals will have the same sign, while apsidal precession would produce anti-correlated residuals. We propose to observe 4 eclipses with Spitzer during Cycle 14, which will allow the two hypotheses to be distinguished with high confidence.

SECULAR EVOLUTION OF BINARIES NEAR MASSIVE BLACK HOLES: FORMATION OF COMPACT BINARIES, MERGER/COLLISION PRODUCTS AND G2-LIKE OBJECTS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Prodan, Snezana; Antonini, Fabio; Perets, Hagai B., E-mail: sprodan@cita.utoronto.ca, E-mail: antonini@cita.utoronto.ca

2015-02-01

Here we discuss the evolution of binaries around massive black holes (MBHs) in nuclear stellar clusters. We focus on their secular evolution due to the perturbation by the MBHs, while simplistically accounting for their collisional evolution. Binaries with highly inclined orbits with respect to their orbits around MBHs are strongly affected by secular processes, which periodically change their eccentricities and inclinations (e.g., Kozai-Lidov cycles). During periapsis approach, dissipative processes such as tidal friction may become highly efficient, and may lead to shrinkage of a binary orbit and even to its merger. Binaries in this environment can therefore significantly change theirmore » orbital evolution due to the MBH third-body perturbative effects. Such orbital evolution may impinge on their later stellar evolution. Here we follow the secular dynamics of such binaries and its coupling to tidal evolution, as well as the stellar evolution of such binaries on longer timescales. We find that stellar binaries in the central parts of nuclear stellar clusters (NSCs) are highly likely to evolve into eccentric and/or short-period binaries, and become strongly interacting binaries either on the main sequence (at which point they may even merge), or through their later binary stellar evolution. The central parts of NSCs therefore catalyze the formation and evolution of strongly interacting binaries, and lead to the enhanced formation of blue stragglers, X-ray binaries, gravitational wave sources, and possible supernova progenitors. Induced mergers/collisions may also lead to the formation of G2-like cloud-like objects such as the one recently observed in the Galactic center.« less

Determination of the atmospheric structure of the BO star companion of SMC X-1 by analysis of Ginga observations

NASA Technical Reports Server (NTRS)

Clark, George W.

1994-01-01

The x-ray phenomena of the binary system SMC X-1/Sk 160, observed with the Ginga and ROSAT x-ray observatories, are compared with computed phenomena derived from a three dimensional hydrodynamical model of the stellar wind perturbed by x-ray heating and ionization which is described in the accompanying paper. In the model the BOI primary star has a line-driven stellar wind in the region of the x-ray shadow and a thermal wind in the region heated by x-rays. We find general agreement between the observed and predicted x-ray spectra throughout the binary orbit cycle, including the extended, variable, and asymmetric eclipse transitions and the period of deep eclipse.

Timing of millisecond pulsars in globular clusters

NASA Astrophysics Data System (ADS)

D'Amico, Nichi; Possenti, Andrea; Manchester, Dick; Johnston, Simon; Kramer, Michael; Sarkissian, John; Lyne, Andrew; Burgay, Marta; Corongiu, Alessandro; Camilo, Fernando; Bailes, Matthew; van Straten, Willem

2011-04-01

Timing of the dozen pulsars discovered by us in P303 is ensuring high quality results: (a) the peculiarities (in position or projected acceleration) of all the 5 millisecond pulsars in NGC6752 suggested the presence of non thermal dynamics in the core, perhaps due to black-holes of intermediate mass; (b) the eclipsing pulsar in NGC6397 is a stereotype for studying the late evolution of exotic binaries. We propose to continue our timing project focusing mostly on NGC6752 at 20cm (in order to measure additional parameters useful to constrain the existence of a black-hole) and NGC6397 at 10cm (for studying the orbital secular evolution, the eclipse region, and the mechanisms leading to the ejection of matter from the binary system).

Timing of millisecond pulsars in globular clusters

NASA Astrophysics Data System (ADS)

D'Amico, Nichi; Possenti, Andrea; Manchester, Dick; Johnston, Simon; Kramer, Michael; Sarkissian, John; Lyne, Andrew; Burgay, Marta; Corongiu, Alessandro; Camilo, Fernando; Bailes, Matthew; van Straten, Willem

2012-10-01

Timing of the dozen pulsars discovered by us in P303 is ensuring high quality results: (a) the peculiarities (in position or projected acceleration) of all the 5 millisecond pulsars in NGC6752 suggested the presence of non thermal dynamics in the core, perhaps due to black-holes of intermediate mass; (b) the eclipsing pulsar in NGC6397 is a stereotype for studying the late evolution of exotic binaries. We propose to continue our timing project focusing mostly on NGC6752 at 20cm (in order to measure additional parameters useful to constrain the existence of a black-hole) and NGC6397 at 10cm (for studying the orbital secular evolution, the eclipse region, and the mechanisms leading to the ejection of matter from the binary system).

Timing of millisecond pulsars in globular clusters

NASA Astrophysics Data System (ADS)

D'Amico, Nichi; Possenti, Andrea; Manchester, Dick; Johnston, Simon; Kramer, Michael; Sarkissian, John; Lyne, Andrew; Burgay, Marta; Corongiu, Alessandro; Camilo, Fernando; Bailes, Matthew; van Straten, Willem

2012-04-01

Timing of the dozen pulsars discovered by us in P303 is ensuring high quality results: (a) the peculiarities (in position or projected acceleration) of all the 5 millisecond pulsars in NGC6752 suggested the presence of non thermal dynamics in the core, perhaps due to black-holes of intermediate mass; (b) the eclipsing pulsar in NGC6397 is a stereotype for studying the late evolution of exotic binaries. We propose to continue our timing project focusing mostly on NGC6752 at 20cm (in order to measure additional parameters useful to constrain the existence of a black-hole) and NGC6397 at 10cm (for studying the orbital secular evolution, the eclipse region, and the mechanisms leading to the ejection of matter from the binary system).

Timing of millisecond pulsars in globular clusters

NASA Astrophysics Data System (ADS)

D'Amico, Nichi; Possenti, Andrea; Manchester, Dick; Johnston, Simon; Kramer, Michael; Sarkissian, John; Lyne, Andrew; Burgay, Marta; Corongiu, Alessandro; Camilo, Fernando; Bailes, Matthew; van Straten, Willem

2011-10-01

Timing of the dozen pulsars discovered by us in P303 is ensuring high quality results: (a) the peculiarities (in position or projected acceleration) of all the 5 millisecond pulsars in NGC6752 suggested the presence of non thermal dynamics in the core, perhaps due to black-holes of intermediate mass; (b) the eclipsing pulsar in NGC6397 is a stereotype for studying the late evolution of exotic binaries. We propose to continue our timing project focusing mostly on NGC6752 at 20cm (in order to measure additional parameters useful to constrain the existence of a black-hole) and NGC6397 at 10cm (for studying the orbital secular evolution, the eclipse region, and the mechanisms leading to the ejection of matter from the binary system).

Timing of millisecond pulsars in globular clusters

NASA Astrophysics Data System (ADS)

D'Amico, Nichi; Possenti, Andrea; Manchester, Dick; Johnston, Simon; Kramer, Michael; Sarkissian, John; Lyne, Andrew; Burgay, Marta; Corongiu, Alessandro; Camilo, Fernando; Bailes, Matthew; van Straten, Willem

2013-04-01

Timing of the dozen pulsars discovered by us in P303 is ensuring high quality results: (a) the peculiarities (in position or projected acceleration) of all the 5 millisecond pulsars in NGC6752 suggested the presence of non thermal dynamics in the core, perhaps due to black-holes of intermediate mass; (b) the eclipsing pulsar in NGC6397 is a stereotype for studying the late evolution of exotic binaries. We propose to continue our timing project focusing mostly on NGC6752 at 20cm (in order to measure additional parameters useful to constrain the existence of a black-hole) and NGC6397 at 10cm (for studying the orbital secular evolution, the eclipse region, and the mechanisms leading to the ejection of matter from the binary system).

White dwarf-main sequence binaries from LAMOST: the DR5 catalogue

NASA Astrophysics Data System (ADS)

Ren, J.-J.; Rebassa-Mansergas, A.; Parsons, S. G.; Liu, X.-W.; Luo, A.-L.; Kong, X.; Zhang, H.-T.

2018-07-01

We present the data release (DR) 5 catalogue of white dwarf-main sequence (WDMS) binaries from the Large sky Area Multi-Object fibre Spectroscopic Telescope (LAMOST). The catalogue contains 876 WDMS binaries, of which 757 are additions to our previous LAMOST DR1 sample and 357 are systems that have not been published before. We also describe a LAMOST-dedicated survey that aims at obtaining spectra of photometrically selected WDMS binaries from the Sloan Digital Sky Survey (SDSS) that are expected to contain cool white dwarfs and/or early-type M dwarf companions. This is a population under-represented in previous SDSS WDMS binary catalogues. We determine the stellar parameters (white dwarf effective temperatures, surface gravities and masses, and M dwarf spectral types) of the LAMOST DR5 WDMS binaries and make use of the parameter distributions to analyse the properties of the sample. We find that, despite our efforts, systems containing cool white dwarfs remain under-represented. Moreover, we make use of LAMOST DR5 and SDSS DR14 (when available) spectra to measure the Na I λλ 8183.27, 8194.81 absorption doublet and/or Hα emission radial velocities of our systems. This allows identifying 128 binaries displaying significant radial velocity variations, 76 of which are new. Finally, we cross-match our catalogue with the Catalina Surveys and identify 57 systems displaying light-curve variations. These include 16 eclipsing systems, two of which are new, and nine binaries that are new eclipsing candidates. We calculate periodograms from the photometric data and measure (estimate) the orbital periods of 30 (15) WDMS binaries.

White dwarf-main sequence binaries from LAMOST: the DR5 catalogue

NASA Astrophysics Data System (ADS)

Ren, J.-J.; Rebassa-Mansergas, A.; Parsons, S. G.; Liu, X.-W.; Luo, A.-L.; Kong, X.; Zhang, H.-T.

2018-03-01

We present the data release (DR) 5 catalogue of white dwarf-main sequence (WDMS) binaries from the Large Area Multi-Object fiber Spectroscopic Telescope (LAMOST). The catalogue contains 876 WDMS binaries, of which 757 are additions to our previous LAMOST DR1 sample and 357 are systems that have not been published before. We also describe a LAMOST-dedicated survey that aims at obtaining spectra of photometrically-selected WDMS binaries from the Sloan Digital Sky Survey (SDSS) that are expected to contain cool white dwarfs and/or early type M dwarf companions. This is a population under-represented in previous SDSS WDMS binary catalogues. We determine the stellar parameters (white dwarf effective temperatures, surface gravities and masses, and M dwarf spectral types) of the LAMOST DR5 WDMS binaries and make use of the parameter distributions to analyse the properties of the sample. We find that, despite our efforts, systems containing cool white dwarfs remain under-represented. Moreover, we make use of LAMOST DR5 and SDSS DR14 (when available) spectra to measure the Na I λλ 8183.27, 8194.81 absorption doublet and/or Hα emission radial velocities of our systems. This allows identifying 128 binaries displaying significant radial velocity variations, 76 of which are new. Finally, we cross-match our catalogue with the Catalina Surveys and identify 57 systems displaying light curve variations. These include 16 eclipsing systems, two of which are new, and nine binaries that are new eclipsing candidates. We calculate periodograms from the photometric data and measure (estimate) the orbital periods of 30 (15) WDMS binaries.

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

NASA Astrophysics Data System (ADS)

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

2017-12-01

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

Kozai-Lidov disc instability

NASA Astrophysics Data System (ADS)

Lubow, Stephen H.; Ogilvie, Gordon I.

2017-08-01

Recent results by Martin et al. showed in 3D smoothed particle hydrodynamics simulations that tilted discs in binary systems can be unstable to the development of global, damped Kozai-Lidov (KL) oscillations in which the discs exchange tilt for eccentricity. We investigate the linear stability of KL modes for tilted inviscid discs under the approximations that the disc eccentricity is small and the disc remains flat. By using 1D equations, we are able to probe regimes of large ratios of outer to inner disc edge radii that are realistic for binary systems of hundreds of astronomical unit separations and are not easily probed by multidimensional simulations. For order unity binary mass ratios, KL instability is possible for a window of disc aspect ratios H/r in the outer parts of a disc that roughly scale as (nb/n)2 ≲ H/r ≲ nb/n, for binary orbital frequency nb and orbital frequency n at the disc outer edge. We present a framework for understanding the zones of instability based on the determination of branches of marginally unstable modes. In general, multiple growing eccentric KL modes can be present in a disc. Coplanar apsidal-nodal precession resonances delineate instability branches. We determine the range of tilt angles for unstable modes as a function of disc aspect ratio. Unlike the KL instability for free particles that involves a critical (minimum) tilt angle, disc instability is possible for any non-zero tilt angle depending on the disc aspect ratio.

GLOBAL ANALYSIS OF KOI-977: SPECTROSCOPY, ASTEROSEISMOLOGY, AND PHASE-CURVE ANALYSIS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hirano, Teruyuki; Sato, Bun'ei; Kobayashi, Atsushi

2015-01-20

We present a global analysis of KOI-977, one of the planet host candidates detected by Kepler. The Kepler Input Catalog (KIC) reports that KOI-977 is a red giant, for which few close-in planets have been discovered. Our global analysis involves spectroscopic and asteroseismic determinations of stellar parameters (e.g., mass and radius) and radial velocity (RV) measurements. Our analyses reveal that KOI-977 is indeed a red giant, possibly in the red clump, but its estimated radius (≳ 20 R {sub ☉} = 0.093 AU) is much larger than KOI-977.01's orbital distance (∼0.027 AU) estimated from its period (P {sub orb} ∼more » 1.35 days) and host star's mass. RV measurements show a small variation, which also contradicts the amplitude of ellipsoidal variations seen in the light curve folded with KOI-977.01's period. Therefore, we conclude that KOI-977.01 is a false positive, meaning that the red giant, for which we measured the radius and RVs, is different from the object that produces the transit-like signal (i.e., an eclipsing binary). On the basis of this assumption, we also perform a light curve analysis including the modeling of transits/eclipses and phase-curve variations, adopting various values for the dilution factor D, which is defined as the flux ratio between the red giant and eclipsing binary. Fitting the whole folded light curve as well as individual transits in the short cadence data simultaneously, we find that the estimated mass and radius ratios of the eclipsing binary are consistent with those of a solar-type star and a late-type star (e.g., an M dwarf) for D ≳ 20.« less