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Sample records for low-mass eclipsing binaries

  1. Low-mass Eclipsing Binaries in the Initial Kepler Data Release

    NASA Astrophysics Data System (ADS)

    Coughlin, J. L.; López-Morales, M.; Harrison, T. E.; Ule, N.; Hoffman, D. I.

    2011-03-01

    We identify 231 objects in the newly released Cycle 0 data set from the Kepler Mission as double-eclipse, detached eclipsing binary systems with T eff < 5500 K and orbital periods shorter than ~32 days. We model each light curve using the JKTEBOP code with a genetic algorithm to obtain precise values for each system. We identify 95 new systems with both components below 1.0 M sun and eclipses of at least 0.1 mag, suitable for ground-based follow-up. Of these, 14 have periods less than 1.0 day, 52 have periods between 1.0 and 10.0 days, and 29 have periods greater than 10.0 days. This new sample of main-sequence, low-mass, double-eclipse, detached eclipsing binary candidates more than doubles the number of previously known systems and extends the sample into the completely heretofore unexplored P > 10.0 day period regime. We find preliminary evidence from these systems that the radii of low-mass stars in binary systems decrease with period. This supports the theory that binary spin-up is the primary cause of inflated radii in low-mass binary systems, although a full analysis of each system with radial-velocity and multi-color light curves is needed to fully explore this hypothesis. Also, we present seven new transiting planet candidates that do not appear among the list of 706 candidates recently released by the Kepler team, or in the Kepler False Positive Catalog, along with several other new and interesting systems. We also present novel techniques for the identification, period analysis, and modeling of eclipsing binaries.

  2. LOW-MASS ECLIPSING BINARIES IN THE INITIAL KEPLER DATA RELEASE

    SciTech Connect

    Coughlin, J. L.; Harrison, T. E.; Ule, N.; Lopez-Morales, M.; Hoffman, D. I.

    2011-03-15

    We identify 231 objects in the newly released Cycle 0 data set from the Kepler Mission as double-eclipse, detached eclipsing binary systems with T{sub eff} < 5500 K and orbital periods shorter than {approx}32 days. We model each light curve using the JKTEBOP code with a genetic algorithm to obtain precise values for each system. We identify 95 new systems with both components below 1.0 M{sub sun} and eclipses of at least 0.1 mag, suitable for ground-based follow-up. Of these, 14 have periods less than 1.0 day, 52 have periods between 1.0 and 10.0 days, and 29 have periods greater than 10.0 days. This new sample of main-sequence, low-mass, double-eclipse, detached eclipsing binary candidates more than doubles the number of previously known systems and extends the sample into the completely heretofore unexplored P > 10.0 day period regime. We find preliminary evidence from these systems that the radii of low-mass stars in binary systems decrease with period. This supports the theory that binary spin-up is the primary cause of inflated radii in low-mass binary systems, although a full analysis of each system with radial-velocity and multi-color light curves is needed to fully explore this hypothesis. Also, we present seven new transiting planet candidates that do not appear among the list of 706 candidates recently released by the Kepler team, or in the Kepler False Positive Catalog, along with several other new and interesting systems. We also present novel techniques for the identification, period analysis, and modeling of eclipsing binaries.

  3. Low Mass Eclipsing Binaries in Sparsely Sampled Time-Domain Surveys: SDSS Stripe 82

    NASA Astrophysics Data System (ADS)

    Bhatti, Waqas; Richmond, M. W.; Ford, H. C.; Petro, L. D.

    2011-01-01

    Observations of a small sample of eclipsing binary systems composed exclusively of low mass stars (< 0.8 Msun, spectral type K and M) indicate that theoretical models of stellar structure and evolution (e.g. Baraffe et al. 1998) systematically under-predict the observed radii by 10%. Tidal effects and rotation-induced magnetic fields in close binaries may be responsible for this disagreement, but the small observed sample of these objects presents difficulties in testing this hypothesis. Large scale time-domain surveys are an effective method for discovery and characterization of these intrinsically faint eclipsing binaries. Here, we present results of a search for periodic variables in multi-band sparsely sampled timeseries data from SDSS Stripe 82, including the discovery of 200 eclipsing binary candidates. These include 51 K and 79 M-dwarf eclipsing binaries as classified by their SDSS colors. We discuss the general properties of this sample, including the period, spectral type, and binary type distributions. For 30 of these objects that have sufficient phase coverage and secure orbital period determinations, we model the SDSS riz-band light-curves using the Wilson-Devinney code (Wilson & Devinney 1971), and determine relative radii, temperatures, luminosities, and orbital inclinations. Finally, we identify 5 M-dwarf eclipsing binaries in this sample with median SDSS r < 18.0 mag that are particularly suitable for photometric and spectroscopic followup observations. These observations will result in precise measurements of the binary components' masses and radii, placing better constraints on the observed mass-radius relation of the lower main-sequence, and the extent of its disagreement with predictions from theoretical models. Based on data from the Sloan Digital Sky Survey (http://www.sdss.org). This research was supported in part by NASA grant NAG5-7697.

  4. Substellar companions in low-mass eclipsing binaries. NSVS 01286630, NSVS 02502726, and NSVS 07453183

    NASA Astrophysics Data System (ADS)

    Wolf, M.; Zasche, P.; Kučáková, H.; Vraštil, J.; Hornoch, K.; Šmelcer, L.; Bílek, F.; Pilarčík, L.; Chrastina, M.

    2016-03-01

    Aims: As part of our long-term observational project we aim to measure very precise mid-eclipse times for low-mass eclipsing binaries, which are needed to accurately determine their period changes. Over two hundred new precise times of minimum light recorded with CCD were obtained for three eclipsing binaries with short orbital periods: NSVS 01286630 (P = 0.38°), NSVS 02502726 (0.56°), and NSVS 07453183 (0.37°). Methods: O-C diagrams of studied stars were analysed using all reliable timings, and new parameters of the light-time effect were obtained. Results: We derived for the first time or improved the very short orbital periods of third bodies of between one and seven years for all measured low-mass systems. We calculated that the lowest masses of the third components are between those of red and brown dwarfs. The multiplicity of these systems also plays an important role in the precise determination of their physical parameters. This research is part of an ongoing collaboration between professional astronomers and the Czech Astronomical Society, Variable Star and Exoplanet Section.

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

    SciTech Connect

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

    2009-08-20

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

  6. PHYSICAL PROPERTIES OF THE LOW-MASS ECLIPSING BINARY NSVS 02502726

    SciTech Connect

    Lee, Jae Woo; Youn, Jae-Hyuck; Kim, Seung-Lee; Lee, Chung-Uk E-mail: jhyoon@kasi.re.kr E-mail: leecu@kasi.re.kr

    2013-01-01

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

  7. Optical flare activity in the low-mass eclipsing binary GJ 3236

    NASA Astrophysics Data System (ADS)

    Parimucha, Š.; Dubovský, P.; Vaňko, M.; Čokina, M.

    2016-09-01

    We present our observations of the low-mass eclipsing binary GJ 3236. We have analyzed a phased RC light-curve and confirmed previously determined fundamental parameters of the components. We detected evolution of the spot(s) and found that there exists a large spot near a polar region of the primary component and another spot either on the primary or the secondary component. We also observed 7 flare events and determined a flare rate of about 0.1 flares per hour. We observed two high energy, long-term flares with a complex light curve and possibly four weak short-term flaring events. A majority of the flares was detected in the RC filter, which indicate their high energy.

  8. DETECTABILITY OF TRANSITING JUPITERS AND LOW-MASS ECLIPSING BINARIES IN SPARSELY SAMPLED PAN-STARRS-1 SURVEY DATA

    SciTech Connect

    Dupuy, Trent J.; Liu, Michael C.

    2009-10-20

    We present detailed simulations of the Pan-STARRS-1 (PS1) multi-epoch, multiband 3pi Survey in order to assess its potential yield of transiting planets and eclipsing binaries. This survey differs from dedicated transit surveys in that it will cover the entire northern sky but provide only sparsely sampled light curves. Since most eclipses would be detected at only a single epoch, the 3pi Survey will be most sensitive to deep eclipses (approx>0.10 mag) caused by Jupiters transiting M dwarfs and eclipsing stellar/substellar binaries. The survey will measure parallaxes for the approx4 x 10{sup 5} stars within 100 pc, which will enable a volume-limited eclipse search, reducing the number of astrophysical false positives compared with previous magnitude-limited searches. Using the best available empirical data, we constructed a model of the extended solar neighborhood that includes stars, brown dwarfs, and a realistic binary population. We computed the yield of deeply eclipsing systems using both a semianalytic and a full Monte Carlo approach. We examined statistical tests for detecting single-epoch eclipses in sparsely sampled data and assessed their vulnerability to false positives due to stellar variability. Assuming a short-period planet frequency of 0.5% for M dwarfs, our simulations predict that about a dozen transiting Jupiters around low-mass stars (M {sub *} < 0.3 M {sub sun}) within 100 pc are potentially detectable in the PS1 3pi Survey, along with approx300 low-mass eclipsing binaries (both component masses <0.5 M {sub sun}), including approx10 eclipsing field brown dwarfs. Extensive follow-up observations would be required to characterize these candidate eclipsing systems, thereby enabling comprehensive tests of structural models and novel insights into the planetary architecture of low-mass stars.

  9. IGR J17451-3022: a dipping and eclipsing low mass X-ray binary

    NASA Astrophysics Data System (ADS)

    Bozzo, E.

    2016-06-01

    We report on the available X-ray data collected by INTEGRAL, Swift, and XMM-Newton during the first outburst of the INTEGRAL transient IGR J17451-3022, discovered in 2014 August. The emission of the source during the 9 months-long outburst was dominated by a thermal component (kT˜14;1.2 keV), most likely produced by an accretion disk. The XMM-Newton observation carried out during the outburst revealed the presence of multiple absorption features in the soft X-ray emission that could be associated to the presence of an ionized absorber lying above the accretion disk, as observed in many high-inclination low mass X-ray binaries. The XMM-Newton data also revealed the presence of partial and rectangular X-ray eclipses (lasting about 820 s), together with dips. The latter can be associated with increases in the overall absorption column density in the direction of the source. The detection of two consecutive X-ray eclipses in the XMM-Newton data allowed us to estimate the source orbital period at Porb=22620.5(-1.8,+2.0) s (1σ c.l.).

  10. IGR J17451–3022: a dipping and eclipsing low mass X-ray binary

    NASA Astrophysics Data System (ADS)

    Bozzo, E.

    2016-06-01

    We report on the available X-ray data collected by INTEGRAL, Swift, and XMM-Newton during the first outburst of the INTEGRAL transient IGR J17451-3022, discovered in 2014 August. The emission of the source during the 9 months-long outburst was dominated by a thermal component (kT˜1.2 keV), most likely produced by an accretion disk. The XMM-Newton observation carried out during the outburst revealed the presence of multiple absorption features in the soft X-ray emission that could be associated to the presence of an ionized absorber lying above the accretion disk, as observed in many high-inclination low mass X-ray binaries. The XMM-Newton data also revealed the presence of partial and rectangular X-ray eclipses (lasting about 820 s), together with dips. The latter can be associated with increases in the overall absorption column density in the direction of the source. The detection of two consecutive X-ray eclipses in the XMM-Newton data allowed us to estimate the source orbital period at Porb=22620.5(‑1.8,+2.0) s (1σ c.l.).

  11. THE EFFECT OF MAGNETIC ACTIVITY ON LOW-MASS STARS IN ECLIPSING BINARIES

    SciTech Connect

    Morales, Juan Carlos; Ribas, Ignasi; Jordi, Carme; Baraffe, Isabelle; Chabrier, Gilles

    2010-07-20

    In recent years, analyses of eclipsing binary systems have unveiled differences between the observed fundamental properties of low-mass stars and those predicted by stellar structure models. Particularly, radius and effective temperatures computed from models are {approx}5%-10% lower and {approx}3%-5% higher than observed, respectively. These discrepancies have been attributed to different factors, notably the high levels of magnetic activity present on these stars. In this paper, we test the effect of magnetic activity both on models and on the observational analysis of eclipsing binaries using a sample of such systems with accurate fundamental properties. Regarding stellar models, we have found that unrealistically high spot coverages need to be assumed to reproduce the observations. Tests considering metallicity effects and missing opacities on models indicate that these are not able to explain the radius discrepancies observed. With respect to the observations, we have tested the effect of several spot distributions on the light curve analysis. Our results show that spots cause systematic deviations on the stellar radii derived from light curve analysis when mainly distributed over the stellar poles. Assuming the existence of polar spots, overall agreement between models and observations is reached when {approx}35% spot coverage is considered on stellar models. Such spot coverage induces a systematic deviation in the radius determination from the light curve analysis of {approx}3% and is also compatible with the modulations observed on the light curves of these systems. Finally, we have found that the effect of activity or rotation on convective transport in partially radiative stars may also contribute to the explanation of the differences seen in some of the systems with shorter orbital periods.

  12. BD -22 5866: A Low-Mass, Quadruple-lined Spectroscopic and Eclipsing Binary

    NASA Astrophysics Data System (ADS)

    Shkolnik, Evgenya; Liu, Michael C.; Reid, I. Neill; Hebb, Leslie; Cameron, Andrew C.; Torres, Carlos A.; Wilson, David M.

    2008-08-01

    We report our discovery of an extremely rare, low-mass, quadruple-lined spectroscopic binary BD -22 5866 (=NLTT 53279, integrated spectral type = M0 V), found during an ongoing search for the youngest M dwarfs in the solar neighborhood. From the cross-correlation function, we are able to measure relative flux levels, estimate the spectral types of the components, and set upper limits on the orbital periods and separations. The resulting system is hierarchical, composed of a K7 + K7 binary and an M1 + M2 binary with semimajor axes of aAsin iA <= 0.06 and aBsin iB <= 0.30 AU. A subsequent search of the SuperWASP photometric database revealed that the K7 + K7 binary is eclipsing with a period of 2.21 days and at an inclination angle of 85°. Within uncertainties of 5%, the masses and radii of both components appear to be equal (0.59 M⊙, 0.61 R⊙). These two tightly orbiting stars (a = 0.035 AU) are in synchronous rotation, causing the observed excess Ca II, Hα, X-ray, and UV emission. The fact that the system was unresolved with published adaptive optics imaging, limits the projected physical separation of the two binaries at the time of the observation to dABlesssim 4.1 AU at the photometric distance of 51 pc. The maximum observed radial velocity difference between the A and B binaries limits the orbit to aABsin iAB <= 6.1 AU. As this tight configuration is difficult to reproduce with current formation models of multiple systems, we speculate that an early dynamical process reduced the size of the system, such as the interaction of the two binaries with a circumquadruple disk. Intensive photometric, spectroscopic, and interferometric monitoring, as well as a parallax measurement of this rare quadruple system, is certainly warranted. Based on observations collected at the W. M. Keck Observatory and the Canada-France-Hawaii Telescope (CFHT). The Keck Observatory is operated as a scientific partnership between the California Institute of Technology, the University

  13. KEPLER STUDIES OF LOW-MASS ECLIPSING BINARIES. I. PARAMETERS OF THE LONG-PERIOD BINARY KIC 6131659

    SciTech Connect

    Bass, Gideon; Orosz, Jerome A.; Welsh, William F.; Windmiller, Gur; Gregg, Trevor Ames; Fetherolf, Tara; Wade, Richard A.; Quinn, Samuel N.

    2012-12-20

    KIC 6131659 is a long-period (17.5 days) eclipsing binary discovered by the Kepler mission. We analyzed six quarters of Kepler data along with supporting ground-based photometric and spectroscopic data to obtain accurate values for the mass and radius of both stars, namely, M{sub 1} = 0.922 {+-} 0.007 M{sub Sun }, R{sub 1} = 0.8800 {+-} 0.0028 R{sub Sun }, and M{sub 2} = 0.685 {+-} 0.005 M{sub Sun }, R{sub 2} = 0.6395 {+-} 0.0061 R{sub Sun }. There is a well-known issue with low-mass (M {approx}< 0.8 M{sub Sun }) stars (in cases where the mass and radius measurement uncertainties are smaller than 2% or 3%) where the measured radii are almost always 5% to 15% larger than expected from evolutionary models, i.e., the measured radii are all above the model isochrones in a mass-radius plane. In contrast, the two stars in KIC 6131659 were found to sit on the same theoretical isochrone in the mass-radius plane. Until recently, all of the well-studied eclipsing binaries with low-mass stars had periods of less than about three days. The stars in such systems may have been inflated by high levels of stellar activity induced by tidal effects in these close binaries. KIC 6131659 shows essentially no evidence of enhanced stellar activity, and our measurements support the hypothesis that the unusual mass-radius relationship observed in most low-mass stars is influenced by strong magnetic activity created by the rapid rotation of the stars in tidally locked, short-period systems. Finally, using short cadence data, we show that KIC 6131657 has one of the smallest measured non-zero eccentricities of a binary with two main-sequence stars, where ecos {omega} (4.57 {+-} 0.02) Multiplication-Sign 10{sup -5}.

  14. Photometric monitoring of open clusters: Low-mass eclipsing binary stars and the stellar mass-luminosity-radius relation

    NASA Astrophysics Data System (ADS)

    Hebb, Leslie

    2006-06-01

    This thesis describes a photometric monitoring survey of Galactic star clusters designed to detect low-mass eclipsing binary star systems through variations in their relative lightcurves. The aim is to use cluster eclipsing binaries to measure the masses and radii of M-dwarf stars with ages and metallicities known from studies of brighter cluster stars. This information will provide an improved calibration of the mass-luminosity-radius relation for low-mass stars, be used to test stellar structure and evolution models, and help quantify the contribution of low-mass stars to the global mass census in the Galaxy. The survey is designed to detect eclipse events in stars of ~0.3 M_sun and consists of 600 Gbytes of raw imaging data on six open clusters with a range of ages (~ 0.15 - 4 Gyr) and metallicites (~ -0.2 - 0.0 dex). The clusters NGC 1647 and M 35 contain excellent candidate systems showing eclipse like variations in brightness and photometry consistent with cluster membership. The analysis of these clusters and the eclipsing M-dwarf stars detected in them are presented. Analysis of the candidate system in NGC 1647 confirms the object as a newly discovered M-dwarf eclipsing binary in the cluster with compenent masses of M 1 = 0.47 ± 0.05[Special characters omitted.] and M 2 = 0.19 ± 0.02[Special characters omitted.] . The small mass ratio ( M 2 / M 1 ) and low secondary mass of this object provide an unprecedented opportunity to test stellar models. We find that no stellar evolution models are consistent with all the properties of both M-dwarf stars in the eclipsing binary. The candidate in M 35 has been confirmed as an M-dwarf eclipsing binary, and the masses of the individual components are estimated to be M 1 ~ 0.25 M_sun and M 2 ~ 0.15 M_sun . Additional high resolution spectroscopic and photometric observations, for which we have applied and been awarded time, are necessary to accurately derive the intrinsic properties of the individual stellar

  15. NSVS 06507557: a low-mass double-lined eclipsing binary

    NASA Astrophysics Data System (ADS)

    Çakırlı, Ö.; Ibanoǧlu, C.

    2010-01-01

    In this paper, we present the results of a detailed spectroscopic and photometric analysis of the V = 13.4 mag low-mass eclipsing binary NSVS 06507557 with an orbital period of 0.515d. We have obtained a series of mid-resolution spectra covering nearly the entire orbit of the system. In addition, we have obtained simultaneous VRI broad-band photometry using a small aperture telescope. From these spectroscopic and photometric data, we have derived the system's orbital parameters and we have determined the fundamental stellar parameters of the two components. Our results indicate that NSVS 06507557 consists of a K9 pre-main-sequence star and an M3 pre-main-sequence star. These have masses of 0.66 +/- 0.09 Msolar and 0.28 +/- 0.05 Msolar and radii of 0.60 +/- 0.03 and 0.44 +/- 0.02 Rsolar, respectively, and are located at a distance of 111 +/- 9 pc. The radius of the less massive secondary component is larger than that of a zero-age main-sequence (ZAMS) star having the same mass. While the radius of the primary component is in agreement with ZAMS, the secondary component appears to be larger by about 35 per cent with respect to its ZAMS counterpart. Night-to-night intrinsic light variations up to 0.2 mag have been observed. In addition, the Hα and Hβ lines and the forbidden line of [OI] are seen in emission. The LiI 6708 Å absorption line is seen in most of the spectra. These features are taken to be signs of the characteristics of classic T Tauri stars. The parameters we have derived are consistent with an age of about 20 Myr, according to stellar evolutionary models. The spectroscopic and photometric results are in agreement with those obtained using theoretical predictions. Based on spectroscopic observations collected at TÜBİTAK (Turkey). E-mail: omur.cakirli@ege.edu.tr

  16. Parameters of two low-mass contact eclipsing binaries near the short-period limit

    NASA Astrophysics Data System (ADS)

    Lohr, M. E.; Hodgkin, S. T.; Norton, A. J.; Kolb, U. C.

    2014-03-01

    The two objects 1SWASP J150822.80-054236.9 and 1SWASP J160156.04+202821.6 were initially detected from their SuperWASP archived light curves as candidate eclipsing binaries with periods close to the short-period cut-off of the orbital period distribution of main-sequence binaries, at ~0.2 d. Using spectroscopic data from the Isaac Newton Telescope in La Palma, Canary Islands, we here confirm them as double-lined spectroscopic and eclipsing binaries, in contact configuration. Following modelling of their visual light curves and radial velocity curves, we determine their component and system parameters to precisions between ~2 and 11%. The first system contains components of 1.07 and 0.55 M⊙, with radii of 0.90 and 0.68 R⊙, respectively; its primary exhibits pulsations with a period of 1/6 of the orbital period of the system. The latter contains components of 0.86 and 0.57 M⊙, with radii of 0.75 and 0.63 R⊙, respectively.

  17. ECLIPSE TIMINGS OF THE TRANSIENT LOW-MASS X-RAY BINARY EXO 0748-676. IV. THE ROSSI X-RAY TIMING EXPLORER ECLIPSES

    SciTech Connect

    Wolff, Michael T.; Ray, Paul S.; Wood, Kent S.; Hertz, Paul L. E-mail: Paul.Ray@nrl.navy.mil E-mail: Paul.Hertz@nasa.gov

    2009-07-01

    We report our complete database of X-ray eclipse timings of the low-mass X-ray binary EXO 0748-676 observed by the Rossi X-Ray Timing Explorer (RXTE) satellite. As of this writing we have accumulated 443 full X-ray eclipses, 392 of which have been observed with the Proportional Counter Array on RXTE. These include both observations where an eclipse was specifically targeted and those eclipses found in the RXTE data archive. Eclipse cycle count has been maintained since the discovery of the EXO 0748-676 system in 1985 February. We describe our observing and analysis techniques for each eclipse and describe improvements we have made since the last compilation by Wolff et al. The principal result of this paper is the database containing the timing results from a seven-parameter fit to the X-ray light curve for each observed eclipse along with the associated errors in the fitted parameters. Based on the standard O - C analysis, EXO 0748-676 has undergone four distinct orbital period epochs since its discovery. In addition, EXO 0748-676 shows small-scale events in the O - C curve that are likely due to short-lived changes in the secondary star.

  18. The orbital ephemeris and eclipse transitions of the low-mass X-ray binary EXO 0748 - 676

    NASA Technical Reports Server (NTRS)

    Parmar, A. N.; Smale, A. P.; Verbunt, F.; Corbet, R. H. D.

    1991-01-01

    Using the eclipses as fiducial markers, an updated ephemeris for EXO 0748 - 676 is derived and evidence is found that between February 1985 and March 1989 the 3.82-h orbital period of EXO 0748 - 676 decreased with a time scale of -5 x 10 to the 6th yr. The sense of this change is the same as that predicted by simple models for the evolution of low-mass X-ray binaries containing main-sequence companions, but is a factor about 100 faster than expected. This rapid change in orbital period could result from the expansion of the companion due to the effects of X-ray heating. The eclipse transition durations are variable, with the shortest observed taking 1.5 s and the longest 40 s. This latter figure is about an order of magnitude too large to be due to absorption effects in the atmosphere of the secondary assuming a Roche geometry and likely stellar temperature. Either flaring activity or the presence of an X-ray heated evaporative wind or a corona may enhance the scale height of the companion's atmosphere producing the extended eclipse transitions.

  19. The orbital ephemeris and eclipse transitions of the low-mass X-ray binary EXO 0748 - 676

    SciTech Connect

    Parmar, A.N.; Smale, A.P.; Verbunt, F.; Corbet, R.H.D. NASA, Goddard Space Flight Center, Greenbelt, MD Utrecht Rijksuniversitet Institute of Space and Astronautical Science, Sagamihara )

    1991-01-01

    Using the eclipses as fiducial markers, an updated ephemeris for EXO 0748 - 676 is derived and evidence is found that between February 1985 and March 1989 the 3.82-h orbital period of EXO 0748 - 676 decreased with a time scale of -5 x 10 to the 6th yr. The sense of this change is the same as that predicted by simple models for the evolution of low-mass X-ray binaries containing main-sequence companions, but is a factor about 100 faster than expected. This rapid change in orbital period could result from the expansion of the companion due to the effects of X-ray heating. The eclipse transition durations are variable, with the shortest observed taking 1.5 s and the longest 40 s. This latter figure is about an order of magnitude too large to be due to absorption effects in the atmosphere of the secondary assuming a Roche geometry and likely stellar temperature. Either flaring activity or the presence of an X-ray heated evaporative wind or a corona may enhance the scale height of the companion's atmosphere producing the extended eclipse transitions. 38 refs.

  20. The Low-Mass Double-Lined Eclipsing Binary CM Draconis

    NASA Astrophysics Data System (ADS)

    Metcalfe, Travis S.; Mathieu, Robert D.; Latham, David W.; Torres, Guillermo

    1994-12-01

    CM Draconis is the least massive main-sequence eclipsing double-lined spectroscopic binary currently known. Consequently, this system offers a unique opportunity to test stellar structure models near the bottom of the main sequence. The orbital solution of Lacy (1977) established the masses and radii of the two components with uncertainties of a few percent, but these errors are too large to distinguish between competing models. We present a new double-lined orbital solution based on 233 echelle spectra obtained with the CfA Digital Speedometers over the past ten years. Radial velocities for both components were determined using TODCOR, a two-dimensional correlation technique developed by Zucker and Mazeh (1994). We derive individual masses of MA = 0.231 +/- 0.002 and MB = 0.214 +/- 0.001 Msun and a mass ratio of q = 0.926 +/- 0.004. When plotted on a mass-radius diagram using the radii derived by Lacy, the slope defined by the two components of CM Draconis agrees well with the model slopes. The ability to distinguish between models is limited by the uncertainties in the radii and the metal abundance. Following the analysis of Paczynski and Sienkiewicz (1984) we derive bulk helium abundances for the two components of YA = 0.31 and YB = 0.30. The uncertainty is these helium abundances relative to each other is nominally +/- 0.02 and depends primarily on the uncertainty in the ratios of the masses and radii. The uncertainty in the absolute helium abundance is considerably larger and depends on the uncertainty in the absolute masses and radii, the parallax, bolometric correction, age, metallicity, and details of the stellar structure models (such as nuclear cross sections). The uncertainty in the absolute helium abundance is nominally +/- 0.05, but improved determinations of the radii, parallax, and bolometric correction are especially needed to confirm and improve this uncertainty. CM Draconis appears to be a member of Population II. Thus, it may be able to provide a

  1. Testing Stellar Evolution Models: Absolute Dimensions of the Low-Mass Eclipsing Binary Star V651 Cassiopeiae

    NASA Astrophysics Data System (ADS)

    Matthews, Allison; Torres, Guillermo

    2015-01-01

    We report accurate values of several key quantities for the low-mass, 0.9968096 day period, double-lined eclipsing binary V651 Cas. We determine accurate values for the masses, radii and temperatures of the primary and secondary as follows: M = 0.8553(81) solar masses, R = 0.957(17) solar radii, and effective temperature = 5733(100) K for the primary component, and M = 0.7564(48) solar masses, R = 0.771(15) solar radii, and effective temperature = 5113(105) for the secondary component, with formal uncertainties shown in parentheses. A comparison with the stellar evolution models from the Dartmouth Stellar Evolution Program suggests an age of 11(1) Gyr for a best-fit metallicity of [Fe/H] = -0.2. While the isochrone mentioned correctly reproduces the measured radii and temperatures of the stars within the current uncertainties, we note that the secondary radius appears marginally larger and the temperature marginally cooler than models would predict. This is consistent with similar discrepancies found for other low-mass stars, generally accredited to surface activity. With further improvement in the measurement errors, and a spectroscopic measure of the metallicity, V651 Cas should be a valuable system for understanding the effects of magnetic activity on the global structure of low-mass stars and for providing guidance to improve stellar evolution models.This work was supported in part by the NSF REU and DoD ASSURE programs under NSF grant no. 1262851 and by the Smithsonian Institution.

  2. Peculiar lapse of periodic eclipsing event at low-mass X-ray binary GRS 1747-312 during Suzaku observation in 2009

    NASA Astrophysics Data System (ADS)

    Saji, Shigetaka; Mori, Hideyuki; Matsumoto, Hironori; Dotani, Tadayasu; Iwai, Masachika; Maeda, Yoshitomo; Mitsuishi, Ikuyuki; Ozaki, Masanobu; Tawara, Yuzuru

    2016-03-01

    GRS 1747-312 is a neutron star low-mass X-ray binary in the globular cluster Terzan 6, located at a distance of 9.5 kpc from the Earth. During its outbursts, periodic eclipses were known to occur. Observations for the outbursts were performed with Chandra in 2004 and Swift in 2013. XMM-Newton observed its quiescent state in 2004. In addition, when Suzaku observed it in 2009 as a part of Galactic center mapping observations, GRS 1747-312 was found to be in a low-luminosity state with Lx ˜ 1.2 × 1035 erg s-1. All of the observations except for XMM-Newton included the time of the eclipses predicted. We analyzed archival data of these observations. During the Chandra and Swift observations, we found clear flux decreases at the expected time of the eclipses. During the Suzaku observation, however, there were no clear signs for the predicted eclipses. The lapse of the predicted eclipses during the Suzaku observation can be explained by a contaminant source quite close to GRS 1747-312. When GRS 1747-312 is in the quiescent state, we observe X-rays from the contaminant source rather than from GRS 1747-312. However, we have no clear evidence for the contaminant source in our data. The lapse might also be explained by thick material (NH > 1024 cm-2) between the neutron star and the companion star, though the origin of the thick material is not clear.

  3. Peculiar lapse of periodic eclipsing event at low-mass X-ray binary GRS 1747-312 during Suzaku observation in 2009

    NASA Astrophysics Data System (ADS)

    Saji, Shigetaka; Mori, Hideyuki; Matsumoto, Hironori; Dotani, Tadayasu; Iwai, Masachika; Maeda, Yoshitomo; Mitsuishi, Ikuyuki; Ozaki, Masanobu; Tawara, Yuzuru

    2016-06-01

    GRS 1747-312 is a neutron star low-mass X-ray binary in the globular cluster Terzan 6, located at a distance of 9.5 kpc from the Earth. During its outbursts, periodic eclipses were known to occur. Observations for the outbursts were performed with Chandra in 2004 and Swift in 2013. XMM-Newton observed its quiescent state in 2004. In addition, when Suzaku observed it in 2009 as a part of Galactic center mapping observations, GRS 1747-312 was found to be in a low-luminosity state with Lx ˜ 1.2 × 1035 erg s-1. All of the observations except for XMM-Newton included the time of the eclipses predicted. We analyzed archival data of these observations. During the Chandra and Swift observations, we found clear flux decreases at the expected time of the eclipses. During the Suzaku observation, however, there were no clear signs for the predicted eclipses. The lapse of the predicted eclipses during the Suzaku observation can be explained by a contaminant source quite close to GRS 1747-312. When GRS 1747-312 is in the quiescent state, we observe X-rays from the contaminant source rather than from GRS 1747-312. However, we have no clear evidence for the contaminant source in our data. The lapse might also be explained by thick material (NH > 1024 cm-2) between the neutron star and the companion star, though the origin of the thick material is not clear.

  4. A Peculiar Lapse of Periodic Eclipsing Event at Low Mass X-ray Binary GRS 1747-312 during Suzaku Observation in 2009

    NASA Astrophysics Data System (ADS)

    Saji, Shigetaka; Mori, Hideyuki; Matsumoto, Hironori; Dotani, Tadayasu; Iwai, Masachika; Maeda, Yoshitomo

    2015-08-01

    The Low Mass X-ray Binary (LMXB) GRS 1747-312 is a part of the globular cluster Terzan 6, located at a distance of 9.5 kpc from the Earth. Based on previous observations performed with BeppoSAX and RXTE, recurrent outbursts are known to occur with an interval of about 130-142 days. During the outbursts, periodic eclipses were discovered. During an eclipsing event, its flux declined precipitously by two orders of magnitude compared to its pre-eclipsing state. The periodic nature and its characteristic decline imply that this is likely a bona fide eclipsing event by an orbiting star. The duration (d) and orbital period (P) were estimated to be d = 2596 sec and P = 0.514980303 days.To investigate further, observations for outbursts were performed with Chandra (2004) and Swift (2013). In addition, XMM-Newton (2004) and Suzaku (2009) caught it at the quiescent state. All of the observations except for XMM-Newton included the time of the eclipses predicted. We analyzed archival data of these observations. The measured 0.5-10 keV flux were 5.7 × 10-10 erg cm-2 s-1 (Chandra), 2.0 × 10-13 (XMM), 1.1 × 10-11 (Suzaku) and 4.4 × 10-10 (Swift). During the Chandra and Swift observations, we found a sudden declining in the observed flux at the expected time of the eclipses. During the Suzaku observation, however, there were no signs for the predicted eclipses.Except for the Suzaku observation, the spectra were well described with a combination of blackbody and Comptonized emission models, commonly used for fitting on the spectra of LMXBs. The Suzaku spectrum, on the other hand, could be described with a Comptonized component covered partially by an absorber with NH ˜ 1023 cm-2 and covering fraction of ˜ 0.9. The spectrum had been becoming softer during the Suzaku observation. The softening may be explained by gradual decrease in the column density and covering fraction of the absorber. The spectral interpretation was consistent with the vanishing of the eclipses: the heavy

  5. Calibrating convective-core overshooting with eclipsing binary systems. The case of low-mass main-sequence stars

    NASA Astrophysics Data System (ADS)

    Valle, G.; Dell'Omodarme, M.; Prada Moroni, P. G.; Degl'Innocenti, S.

    2016-03-01

    Context. Double-lined eclipsing binaries have often been adopted in literature to calibrate the extension of the convective-core overshooting beyond the border defined by the Schwarzschild criterion. Aims: In a robust statistical way, we quantify the magnitude of the uncertainty that affects the calibration of the overshooting efficiency parameter β that is owing to the uncertainty on the observational data. We also quantify the biases on the β determination that is caused by the lack of constraints on the initial helium content and on the efficiencies of the superadiabatic convection and microscopic diffusion. Methods: We adopted a modified grid-based SCEPtER pipeline to recover the β parameter from synthetic stellar data. Our grid spans the mass range [1.1; 1.6] M⊙ and evolutionary stages from the zero-age main sequence (MS) to the central hydrogen depletion. The β estimates were obtained by generalising the maximum likelihood technique described in our previous works. As observational constraint, we adopted the effective temperatures, [Fe/H], masses, and radii of the two stars. Results: By means of Monte Carlo simulations, adopting a reference scenario of mild overshooting β = 0.2 for the synthetic data, and taking typical observational errors into account, we found both large statistical uncertainties and biases on the estimated values of β. For the first 80% of the MS evolution, β is biased by about -0.04, with the 1σ error practically unconstrained in the whole explored range [0.0; 0.4]. In the last 5% of the evolution the bias vanishes and the 1σ error is about 0.05. The 1σ errors are similar when adopting different reference values of β. Interestingly, for synthetic data computed without convective-core overshooting, the estimated β is biased by about 0.12 in the first 80% of the MS evolution, and by 0.05 afterwards. Assuming an uncertainty of ±1 in the helium-to-metal enrichment ratio ΔY/ ΔZ, we found a large systematic uncertainty in the

  6. 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

  7. THIRTY NEW LOW-MASS SPECTROSCOPIC BINARIES

    SciTech Connect

    Shkolnik, Evgenya L.; Hebb, Leslie; Cameron, Andrew C.; Liu, Michael C.; Neill Reid, I. E-mail: Andrew.Cameron@st-and.ac.u E-mail: mliu@ifa.hawaii.ed

    2010-06-20

    As part of our search for young M dwarfs within 25 pc, we acquired high-resolution spectra of 185 low-mass stars compiled by the NStars project that have strong X-ray emission. By cross-correlating these spectra with radial velocity standard stars, we are sensitive to finding multi-lined spectroscopic binaries. We find a low-mass spectroscopic binary fraction of 16% consisting of 27 SB2s, 2 SB3s, and 1 SB4, increasing the number of known low-mass spectroscopic binaries (SBs) by 50% and proving that strong X-ray emission is an extremely efficient way to find M-dwarf SBs. WASP photometry of 23 of these systems revealed two low-mass eclipsing binaries (EBs), bringing the count of known M-dwarf EBs to 15. BD-22 5866, the ESB4, was fully described in 2008 by Shkolnik et al. and CCDM J04404+3127 B consists of two mid-M stars orbiting each other every 2.048 days. WASP also provided rotation periods for 12 systems, and in the cases where the synchronization time scales are short, we used P{sub rot} to determine the true orbital parameters. For those with no P{sub rot}, we used differential radial velocities to set upper limits on orbital periods and semimajor axes. More than half of our sample has near-equal-mass components (q > 0.8). This is expected since our sample is biased toward tight orbits where saturated X-ray emission is due to tidal spin-up rather than stellar youth. Increasing the samples of M-dwarf SBs and EBs is extremely valuable in setting constraints on current theories of stellar multiplicity and evolution scenarios for low-mass multiple systems.

  8. KEPLER CYCLE 1 OBSERVATIONS OF LOW-MASS STARS: NEW ECLIPSING BINARIES, SINGLE STAR ROTATION RATES, AND THE NATURE AND FREQUENCY OF STARSPOTS

    SciTech Connect

    Harrison, T. E.; Coughlin, J. L.; Ule, N. M.; Lopez-Morales, M. E-mail: jlcough@nmsu.edu E-mail: mlopez@ieec.uab.es

    2012-01-15

    We have analyzed Kepler light curves for 849 stars with T{sub eff} {<=} 5200 K from our Cycle 1 Guest Observer program. We identify six new eclipsing binaries, one of which has an orbital period of 29.91 days and two of which are probably W UMa variables. In addition, we identify a candidate 'warm Jupiter' exoplanet. We further examine a subset of 670 sources for variability. Of these objects, 265 stars clearly show periodic variability that we assign to rotation of the low-mass star. At the photometric precision level provided by Kepler, 251 of our objects showed no evidence for variability. We were unable to determine periods for 154 variable objects. We find that 79% of stars with T{sub eff} {<=} 5200 K are variable. The rotation periods we derive for the periodic variables span the range 0.31 days {<=} P{sub rot} {<=} 126.5 days. A considerable number of stars with rotation periods similar to the solar value show activity levels that are 100 times higher than the Sun. This is consistent with results for solar-like field stars. As has been found in previous studies, stars with shorter rotation periods generally exhibit larger modulations. This trend flattens beyond P{sub rot} = 25 days, demonstrating that even long-period binaries may still have components with high levels of activity and investigating whether the masses and radii of the stellar components in these systems are consistent with stellar models could remain problematic. Surprisingly, our modeling of the light curves suggests that the active regions on these cool stars are either preferentially located near the rotational poles, or that there are two spot groups located at lower latitudes, but in opposing hemispheres.

  9. Orbital and physical parameters of eclipsing binaries from the All-Sky Automated Survey catalogue. III. Two new low-mass systems with rapidly evolving spots

    NASA Astrophysics Data System (ADS)

    Hełminiak, K. G.; Konacki, M.; Złoczewski, K.; Ratajczak, M.; Reichart, D. E.; Ivarsen, K. M.; Haislip, J. B.; Crain, J. A.; Foster, A. C.; Nysewander, M. C.; Lacluyze, A. P.

    2011-03-01

    Aims: We present the results of our spectroscopic and photometric analysis of two newly discovered low-mass detached eclipsing binaries found in the All-Sky Automated Survey (ASAS) catalogue: ASAS J093814-0104.4 and ASAS J212954-5620.1. Methods: Using the Grating Instrument for Radiation Analysis with a Fibre-Fed Echelle (GIRAFFE) on the 1.9-m Radcliffe telescope at the South African Astronomical Observatory (SAAO) and the University College London Echelle Spectrograph (UCLES) on the 3.9-m Anglo-Australian Telescope, we obtained high-resolution spectra of both objects and derived their radial velocities (RVs) at various orbital phases. The RVs of both objects were measured with the two-dimensional cross-correlation technique (TODCOR) using synthetic template spectra as references. We also obtained V and I band photometry using the 1.0-m Elizabeth telescope at SAAO and the 0.4-m Panchromatic Robotic Optical Monitoring and Polarimetry Telescopes (PROMPT) located at the Cerro Tololo Inter-American Observatory (CTIO). The orbital and physical parameters of the systems were derived with PHOEBE and JKTEBOP codes. We compared our results with several sets of widely-used isochrones. Results: Our multi-epoch photometric observations demonstrate that both objects show significant out-of-eclipse modulations, which vary in time. We believe that this effect is caused by stellar spots, which evolve on time scales of tens of days. For this reason, we constructed our models on the basis of photometric observations spanning short time scales (less than a month). Our modeling indicates that (1) ASAS J093814-0104.04 is a main sequence active system with nearly-twin components with masses of M1 = 0.771 ± 0.033 M⊙, M2 = 0.768 ± 0.021 M⊙ and radii of R1 = 0.772 ± 0.012 R⊙ and R2 = 0.769 ± 0.013 R⊙. (2) ASAS J212954-5620.1 is a main sequence active binary with component masses of M1 = 0.833 ± 0.017 M⊙, M2 = 0.703 ± 0.013 M⊙ and radii of R1 = 0.845 ± 0.012 R⊙ and R2

  10. The G+M eclipsing binary V530 Orionis: a stringent test of magnetic stellar evolution models for low-mass stars

    SciTech Connect

    Torres, Guillermo; Lacy, Claud H. Sandberg; Pavlovski, Krešimir; Feiden, Gregory A.; Sabby, Jeffrey A.; Bruntt, Hans; Clausen, Jens Viggo

    2014-12-10

    We report extensive photometric and spectroscopic observations of the 6.1 day period, G+M-type detached double-lined eclipsing binary V530 Ori, an important new benchmark system for testing stellar evolution models for low-mass stars. We determine accurate masses and radii for the components with errors of 0.7% and 1.3%, as follows: M {sub A} = 1.0038 ± 0.0066 M {sub ☉}, M {sub B} = 0.5955 ± 0.0022 M {sub ☉}, R {sub A} = 0.980 ± 0.013 R {sub ☉}, and R {sub B} = 0.5873 ± 0.0067 R {sub ☉}. The effective temperatures are 5890 ± 100 K (G1 V) and 3880 ± 120 K (M1 V), respectively. A detailed chemical analysis probing more than 20 elements in the primary spectrum shows the system to have a slightly subsolar abundance, with [Fe/H] = –0.12 ± 0.08. A comparison with theory reveals that standard models underpredict the radius and overpredict the temperature of the secondary, as has been found previously for other M dwarfs. On the other hand, models from the Dartmouth series incorporating magnetic fields are able to match the observations of the secondary star at the same age as the primary (∼3 Gyr) with a surface field strength of 2.1 ± 0.4 kG when using a rotational dynamo prescription, or 1.3 ± 0.4 kG with a turbulent dynamo approach, not far from our empirical estimate for this star of 0.83 ± 0.65 kG. The observations are most consistent with magnetic fields playing only a small role in changing the global properties of the primary. The V530 Ori system thus provides an important demonstration that recent advances in modeling appear to be on the right track to explain the long-standing problem of radius inflation and temperature suppression in low-mass stars.

  11. Cyclic period changes and the light-time effect in eclipsing binaries: A low-mass companion around the system VV Ursae Majoris

    NASA Astrophysics Data System (ADS)

    Tanrıver, Mehmet

    2015-04-01

    In this article, a period analysis of the late-type eclipsing binary VV UMa is presented. This work is based on the periodic variation of eclipse timings of the VV UMa binary. We determined the orbital properties and mass of a third orbiting body in the system by analyzing the light-travel time effect. The O-C diagram constructed for all available minima times of VV UMa exhibits a cyclic character superimposed on a linear variation. This variation includes three maxima and two minima within approximately 28,240 orbital periods of the system, which can be explained as the light-travel time effect (LITE) because of an unseen third body in a triple system that causes variations of the eclipse arrival times. New parameter values of the light-time travel effect because of the third body were computed with a period of 23.22 ± 0.17 years in the system. The cyclic-variation analysis produces a value of 0.0139 day as the semi-amplitude of the light-travel time effect and 0.35 as the orbital eccentricity of the third body. The mass of the third body that orbits the eclipsing binary stars is 0.787 ± 0.02 M⊙, and the semi-major axis of its orbit is 10.75 AU.

  12. Thirty New Low-mass Spectroscopic Binaries

    NASA Astrophysics Data System (ADS)

    Shkolnik, Evgenya L.; Hebb, Leslie; Liu, Michael C.; Reid, I. Neill; Collier Cameron, Andrew

    2010-06-01

    As part of our search for young M dwarfs within 25 pc, we acquired high-resolution spectra of 185 low-mass stars compiled by the NStars project that have strong X-ray emission. By cross-correlating these spectra with radial velocity standard stars, we are sensitive to finding multi-lined spectroscopic binaries. We find a low-mass spectroscopic binary fraction of 16% consisting of 27 SB2s, 2 SB3s, and 1 SB4, increasing the number of known low-mass spectroscopic binaries (SBs) by 50% and proving that strong X-ray emission is an extremely efficient way to find M-dwarf SBs. WASP photometry of 23 of these systems revealed two low-mass eclipsing binaries (EBs), bringing the count of known M-dwarf EBs to 15. BD-22 5866, the ESB4, was fully described in 2008 by Shkolnik et al. and CCDM J04404+3127 B consists of two mid-M stars orbiting each other every 2.048 days. WASP also provided rotation periods for 12 systems, and in the cases where the synchronization time scales are short, we used P rot to determine the true orbital parameters. For those with no P rot, we used differential radial velocities to set upper limits on orbital periods and semimajor axes. More than half of our sample has near-equal-mass components (q > 0.8). This is expected since our sample is biased toward tight orbits where saturated X-ray emission is due to tidal spin-up rather than stellar youth. Increasing the samples of M-dwarf SBs and EBs is extremely valuable in setting constraints on current theories of stellar multiplicity and evolution scenarios for low-mass multiple systems. Based on observations collected at the W. M. Keck Observatory, the Canada-France-Hawaii Telescope and by the WASP Consortium. The Keck Observatory is operated as a scientific partnership between the California Institute of Technology, the University of California, and NASA, and was made possible by the generous financial support of the W. M. Keck Foundation. The CFHT is operated by the National Research Council of Canada

  13. Modeling the System Parameters of 2M 1533+3759: A New Longer Period Low-Mass Eclipsing sdB+dM Binary

    NASA Astrophysics Data System (ADS)

    For, B.-Q.; Green, E. M.; Fontaine, G.; Drechsel, H.; Shaw, J. S.; Dittmann, J. A.; Fay, A. G.; Francoeur, M.; Laird, J.; Moriyama, E.; Morris, M.; Rodríguez-López, C.; Sierchio, J. M.; Story, S. M.; Strom, A.; Wang, C.; Adams, S. M.; Bolin, D. E.; Eskew, M.; Chayer, P.

    2010-01-01

    We present new photometric and spectroscopic observations for 2M 1533+3759 (= NSVS 07826147), the seventh eclipsing subdwarf B star + M dwarf (sdB+dM) binary ever found. It has an orbital period of 0.16177042 days, or ~3.88 hr, significantly longer than the 2.3-3.0 hr periods of the other known eclipsing sdB+dM systems. Spectroscopic analysis of the hot primary yields T eff = 29230 ± 125 K, log g = 5.58 ± 0.03, and log N(He)/N(H) = -2.37 ± 0.05. The sdB velocity amplitude is K 1 = 71.1 ± 1.0 km s-1. The only detectable light contribution from the secondary is due to the surprisingly strong reflection effect, whose peak-to-peak BVRI amplitudes are 0.10, 0.13, 0.15, and 0.19 mag, respectively. Light-curve modeling produced several solutions corresponding to different values of the system mass ratio, q (M 2/M 1), but only one is consistent with a core helium burning star, q = 0.301. The orbital inclination is 86fdg6. The sdB primary mass is M 1 = 0.376 ± 0.055 M sun and its radius is R 1 = 0.166 ± 0.007 R sun. 2M 1533+3759 joins PG 0911+456 (and possibly also HS 2333+3927) in having an unusually low mass for an sdB star. SdB stars with masses significantly lower than the canonical value of 0.48 M sun, down to as low as 0.30 M sun, were theoretically predicted by Han et al., but observational evidence has only recently begun to confirm the existence of such stars. The existence of core helium burning stars with masses lower than 0.40-0.43 M sun implies that at least some sdB progenitors have initial main-sequence masses of 1.8-2.0 M sun or more, i.e., they are at least main-sequence A stars. The orbital separation in 2M 1533+3759 is a = 0.98 ± 0.04R sun. The secondary has M 2 = 0.113 ± 0.017 M sun, R 2 = 0.152 ± 0.005R sun, and T_eff_{2} = 3100 ± 600 K, consistent with a main-sequence M5 star. If 2M 1533+3759 becomes a cataclysmic variable (CV), its orbital period will be 1.6 hr, below the CV period gap.

  14. A POSSIBLE SIGNATURE OF LENSE-THIRRING PRECESSION IN DIPPING AND ECLIPSING NEUTRON-STAR LOW-MASS X-RAY BINARIES

    SciTech Connect

    Homan, Jeroen

    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-star 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.

  15. Spectroscopic Orbits for Kepler FOV Eclipsing Binaries

    NASA Astrophysics Data System (ADS)

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

    2013-02-01

    We are currently involved in a four year program of precise eclipsing binary photometry with the NASA Kepler Observatory. Our goal is to search for variations in minimum light timing for intermediate mass eclipsing binaries. Such periodic variations will reveal the reflex motion caused by any distant, low mass object that orbits the close binary. it Kepler's unprecedented accuracy and continuous observations provide a unique opportunity to detect the low mass companions that are predicted to result from the angular momentum of the natal cloud. The goal of this proposal is to obtain blue spectra of short period (0.9-6d) eclipsing binaries, derive radial velocities, and produce a double-lined spectroscopic orbit (as well as estimates of the stellar effective temperatures, gravities, and metallicities). Combined with the it Kepler light curve, we will determine very accurate masses and radii for the members of the close binary, which will yield the mass-inclination product M_3 sin i for any companions detected by light travel time or other effects. An extended sample of eclipsing binaries with longer periods (up to 50d) is now being investigated to test whether the presence of a tertiary companion declines with increasing period. We propose to obtain a single spectrum at quadrature for the brightest 48 stars in this expanded sample to characterize the effective temperatures and total mass contained in these systems.

  16. Outburst from low-mass X-ray binary GRS 1747-312 in Terzan 6

    NASA Astrophysics Data System (ADS)

    Bahramian, A.; Heinke, C. O.; Sivakoff, G. R.; Kennea, J. A.; Wijnands, R.; Altamirano, D.

    2016-05-01

    GRS 1747-312 is an eclipsing transient low-mass X-ray binary in the core of the globular cluster Terzan 6. This source shows regular outbursts ~ every 6 months and, due to its eclipsing behaviour, has an accurately-constrained orbital period (12.36 hrs, in't Zand et al. 2003, A & A, 406, 233).

  17. Combining Astrometry and Light-time Effect: Low-mass Companions around Eclipsing Systems

    NASA Astrophysics Data System (ADS)

    Ribas, I.

    2005-07-01

    We discuss a method to determine orbital properties and masses of low-mass bodies orbiting eclipsing binaries based on combined analyses of light-travel time (LTT) and astrometry. The presence of a third body causes the relative distance of the eclipsing pair to the Earth to change as it orbits the barycenter of the triple system, thus causing periodic variations of the eclipse arrival times. Studies of the eclipsing systems V471 Tau and R CMa are presented to illustrate the method. The eclipse timings of V471 Tau indicate the presence of a third body with substellar minimum mass. In R CMa the companion is an M-type star or a white dwarf with a minimum mass of about 0.3 M⊙. The same reflex motion responsible for LTT effects also causes a displacement of the binary pair around the barycenter. The combination of the LTT analysis and accurate astrometry leads to the determination of the orbital inclination and thus to a full characterization of the orbital and physical properties of the tertiary component. With the upcoming microarcsecond-level astrometric missions, the technique that we discuss can be successfully applied to detect long-period planetary-size objects and brown dwarfs around eclipsing binaries.

  18. Substellar objects around the sdB eclipsing Binaries

    NASA Astrophysics Data System (ADS)

    Zhu, Liying; Qian, Shengbang; Liao, Wenping; Zhao, Ergang; Li, Linjia

    2016-07-01

    The sdB-type eclipsing binary consists a very hot subdwarf B (sdB) type primary and a low mass secondary with short period. They are detached binaries and show very narrow eclipse profiles, which benefits the determination of the precise eclipse times. With the precise times of light minimum, we can detected small mass objects around them by analyzing the observed-calculated (O-C) curve based on the light time effect. For searching the substellar objects orbiting around the binaries, we have monitored sdB-type eclipsing binaries for decades. A group of brown dwarfs and planets have been detected since then. In the present paper, we focus on the target NSVS07826147, which may be another exoplanet host candidate among the group of the sdB-type eclipsing binaries.

  19. Multiples Among Detached Eclipsing Binaries from the ASAS Catalog

    NASA Astrophysics Data System (ADS)

    Hełminiak, K. G.; Konacki, M.; Ratajczak, M.; Jordán, A.; Espinoza, N.; Brahm, R.; Kambe, E.; Ukita, N.

    2015-07-01

    We have been conducting a spectroscopic survey of detached eclipsing binaries (DEBs) from the All-Sky Automated Survey (ASAS) database for more than three years. Thousands of high-resolution spectra of >300 systems have been secured, and used for radial velocity measurements and spectral analysis. We have found a zoo of multiple systems in our sample, such as spectroscopic triples and quadruples, visual binaries with eclipsing components, and circumbinary low-mass companions, including sub-stellar-mass candidates.

  20. PHOEBE: PHysics Of Eclipsing BinariEs

    NASA Astrophysics Data System (ADS)

    Prsa, Andrej; Matijevic, Gal; Latkovic, Olivera; Vilardell, Francesc; Wils, Patrick

    2011-06-01

    PHOEBE (PHysics Of Eclipsing BinariEs) is a modeling package for eclipsing binary stars, built on top of the widely used WD program (Wilson & Devinney 1971). This introductory paper overviews most important scientific extensions (incorporating observational spectra of eclipsing binaries into the solution-seeking process, extracting individual temperatures from observed color indices, main-sequence constraining and proper treatment of the reddening), numerical innovations (suggested improvements to WD's Differential Corrections method, the new Nelder & Mead's downhill Simplex method) and technical aspects (back-end scripter structure, graphical user interface). While PHOEBE retains 100% WD compatibility, its add-ons are a powerful way to enhance WD by encompassing even more physics and solution reliability.

  1. Recent Minima of 193 Eclipsing Binary Stars

    NASA Astrophysics Data System (ADS)

    Samolyk, G.

    2016-06-01

    This paper continues the publication of times of minima for eclipsing binary stars from observations reported to the AAVSO Eclipsing Binary section. Times of minima from CCD observations received by the author from November 2015 through January 2016 are presented.

  2. THE BINARY FRACTION OF LOW-MASS WHITE DWARFS

    SciTech Connect

    Brown, Justin M.; Kilic, Mukremin; Brown, Warren R.; Kenyon, Scott J.

    2011-04-01

    We describe spectroscopic observations of 21 low-mass ({<=}0.45 M{sub sun}) white dwarfs (WDs) from the Palomar-Green survey obtained over four years. We use both radial velocities and infrared photometry to identify binary systems, and find that the fraction of single, low-mass WDs is {<=}30%. We discuss the potential formation channels for these single stars including binary mergers of lower-mass objects. However, binary mergers are not likely to explain the observed number of single low-mass WDs. Thus, additional formation channels, such as enhanced mass loss due to winds or interactions with substellar companions, are likely.

  3. 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

  4. 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.

  5. Radius constraints from high-speed photometry of 20 low-mass white dwarf binaries

    SciTech Connect

    Hermes, J. J.; Brown, Warren R.; Kilic, Mukremin; Gianninas, A.; Chote, Paul; Sullivan, D. J.; Winget, D. E.; Bell, Keaton J.; Falcon, R. E.; Winget, K. I.; Harrold, Samuel T.; Montgomery, M. H.; Mason, Paul A.

    2014-09-01

    We carry out high-speed photometry on 20 of the shortest-period, detached white dwarf binaries known and discover systems with eclipses, ellipsoidal variations (due to tidal deformations of the visible white dwarf), and Doppler beaming. All of the binaries contain low-mass white dwarfs with orbital periods of less than four hr. Our observations identify the first eight tidally distorted white dwarfs, four of which are reported for the first time here. We use these observations to place empirical constraints on the mass-radius relationship for extremely low-mass (≤0.30 M {sub ☉}) white dwarfs. We also detect Doppler beaming in several of these binaries, which confirms their high-amplitude radial-velocity variability. All of these systems are strong sources of gravitational radiation, and long-term monitoring of those that display ellipsoidal variations can be used to detect spin-up of the tidal bulge due to orbital decay.

  6. ROTATIONAL DOPPLER BEAMING IN ECLIPSING BINARIES

    SciTech Connect

    Groot, Paul J.

    2012-01-20

    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 photometric 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.

  7. Eclipse Binary System BB Pegasus

    NASA Astrophysics Data System (ADS)

    Snyder, Leroy F.

    2008-05-01

    CCD ground-based photometry of the contact binary system BB Pegasus is presented along with analyses of the light curve. Recent radial velocity data with these obtained light curves were used to compute parameters. These results are compared with published values computed using spectroscopic values. The light curve displays total annular eclipses in the primary. The period is very short, equal to 0.3615015 days. A recent spectroscopic study indicates the existence of a third body. Three times of minimums were gathered for this poster paper and when added to those found in the literature a plotted quadratic ephemeris displays a sine-like variation of the O -- C curve indicating a tertiary component to the system. The light curve of this system shows an asymmetry in which the maximum after primary eclipse is higher than the other maximum, O'Connell effect. Two small cool stellar spots on star number 1 were used to make the parameter model fit the light curve data.

  8. Eclipsing Binaries: The Primary Distance Indicator

    NASA Astrophysics Data System (ADS)

    Kang, Y.-W.; Hong, K.-S.; Lee, J.

    2007-06-01

    we have investigated how much confidence we can place in eclipsing binaries as distance indicators. The absolute visual magnitudes and the photometric distances of the selected 318 eclipsing binaries were calculated and compared with those calculated from Hipparcos parallaxes. The absolute magnitudes and distances of eclipsing binary systems deduced from analysis of light curves and radial velocity curves are confirmed to have the same accuracy as the Hipparcos parallaxes within an error of 10 percent of the parallax value. This means that photometric distances are accurate enough over a couple thousand parsecs on the basis of the eclipsing binaries used in this paper. The photometric distances of contact binaries show good agreement with those of Rucinski (1996).

  9. Eclipsing binaries in the ASAS survey

    NASA Astrophysics Data System (ADS)

    Nedoroščík, J.; Vaňko, M.; Pribulla, T.

    2014-03-01

    We present a statistical investigation of eclipsing binaries presented in the ASAS (http://www.astrouw.edu.pl/asas/?page=download) survey. Applying the Fourier analysis on the ASAS light curves, we used the relations between coefficients to infer principal properties of eclipsing binaries. The systems with eccentric orbits were found and for the same sample the minimum eccentricity was estimated. We also selected short-period detached eclipsing binaries suitable for the detection of circumbinary exoplanets. Systems with the equal minima depth were also discussed.

  10. Minima Times of Selected Eclipsing Binaries

    NASA Astrophysics Data System (ADS)

    Parimucha, S.; Dubovsky, P.; Kudak, V.; Perig, V.

    2016-05-01

    We present 221 CCD minima times of the 76 selected eclipsing binaries obtained during 2013-2016 at Observatory at Kolonica Saddle in Slovakia and Observatory of Laboratory of Space Research, Uzhhorod National University in Ukraine

  11. 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.

  12. Eclipsing Binaries: Precise Clocks to Detect Extrasolar Planets

    NASA Astrophysics Data System (ADS)

    Kundra, Emil; Pribulla, Theodor; Vaňko, Martin; Hambálek, Ľubomír

    2014-04-01

    Project Dwarf is a new observing campaign focused on the detection of substellar companions to low-mass (composed of late-type, subdwarf (sd) or/and white dwarf (WD) components) detached eclipsing binaries using minima timing. The crucial condition for the object selection for this campaign is possibility to determine times of the minima with high precision. This is naturally fullfilled for eclipsing binaries with deep and narrow minima or systems hosting a WD component showing fast ingress or egress. The observing project includes three groups of close eclipsing binaries indicating presence of substellar circum-binary components: (i) systems with K or/and M dwarf components (ii) systems with hot subdwarf (sd) and M dwarf components (iii) systems with white dwarf (WD) component(s). The sample of the eclipsing systems have orbital periods in range of 0.1 to almost 3 days and their brightness fits possibilities of small telescopes equipped with a low-end CCD camera and at least VRI filter set. Such kind of telescopes allow us to develop observing network including also amateur astronomers.

  13. Discovery of Low Mass Binary with Super Jupiter Companion

    NASA Astrophysics Data System (ADS)

    Anthes Rich, Evan; Wisniewski, John P.; Hashimoto, Jun; Brandt, Timothy; Kuzuhara, Masayuki; Tamura, Motohide

    2015-12-01

    Transit and radial velocity surveys have been prolific in detecting ~2000 confirmed planets to date. While few directly imaged planets have detected, such systems provide a unique scientific opportunity to probe exoplanets at larger angular separation, younger ages, and study their atmospheres. We present new L- and M-band AO observations, obtained with IRCS on Subaru, of a super Jupiter companion orbiting a cool dwarf. We show that the central object is likely a binary, thereby making this system the first likely directly imaged planetary mass companion surrounding a low mass binary system.

  14. Most Double Degenerate Low-mass White Dwarf Binaries Merge

    NASA Astrophysics Data System (ADS)

    Brown, Warren R.; Kilic, Mukremin; Kenyon, Scott J.; Gianninas, A.

    2016-06-01

    We estimate the merger rate of double degenerate binaries containing extremely low mass (ELM; \\lt 0.3 M ⊙) white dwarfs (WDs) in the Galaxy. Such WDs are detectable for timescales of 0.1–1 Gyr in the ELM Survey; the binaries they reside in have gravitational wave merger times of 0.001–100 Gyr. To explain the observed distribution requires that most ELM WD binary progenitors detach from the common envelope phase with <1 hr orbital periods. We calculate the local space density of ELM WD binaries and estimate a merger rate of 3 × 10‑3 yr‑1 over the entire disk of the Milky Way; the merger rate in the halo is 10 times smaller. The ELM WD binary merger rate exceeds by a factor of 40 the formation rate of stable mass transfer AM CVn binaries, marginally exceeds the rate of underluminous supernovae, and is identical to the formation rate of R CrB stars. On this basis, we conclude that ELM WD binaries can be the progenitors of all observed AM CVn and possibly underluminous supernovae; however, the majority of He+CO WD binaries go through unstable mass transfer and merge, e.g., into single massive ∼1 M ⊙ WDs.

  15. GBS-discovered quiescent X-ray binaries: XMM eclipse duration and VLT spectra

    NASA Astrophysics Data System (ADS)

    Jonker, Peter

    2013-10-01

    We propose to use XMM to observe eclipsing probable quiescent low-mass X-ray binaries selected from the Galactic Bulge Survey. The XMM data are crucial to determine the eclipsing duration, one cannot do this as accurately from optical light curves as from X-ray light curves as the X-ray emission region is small compared to the mass donor star. Using the XMM eclipse duration and the VLT spectroscopy we can determine virtually model independent masses of the compact objects. Furthermore, we may select different mass ratio systems favoring low-mass black holes.

  16. Eclipsing binaries in the MOST satellite fields

    NASA Astrophysics Data System (ADS)

    Pribulla, T.; Rucinski, S. M.; Latham, D. W.; Quinn, S. N.; Siwak, M.; Matthews, J. M.; Kuschnig, R.; Rowe, J. F.; Guenther, D. B.; Moffat, A. F. J.; Sasselov, D.; Walker, G. A. H.; Weiss, W. W.

    2010-04-01

    Sixteen new eclipsing binaries have been discovered by the MOST satellite among guide stars used to point its telescope in various fields. Several previously known eclipsing binaries were also observed by MOST with unprecedented quality. Among the objects we discuss in more detail are short-period eclipsing binaries with eccentric orbits in young open clusters: V578 Mon in NGC 2244 and HD 47934 in NGC 2264. Long nearly-continuous photometric runs made it possible to discover three long-period eclipsing binaries with orbits seen almost edge-on: HD 45972 with P = 28.1 days and two systems (GSC 154 1247 and GSC 2141 526) with P > 25 days. The high precision of the satellite data led to discoveries of binaries with very shallow eclipses (e.g., HD 46180 with A = 0.016 mag, and HD 47934 with A = 0.025 mag). Ground-based spectroscopy to support the space-based photometry was used to refine the models of several of the systems. Based on photometric data from MOST, a Canadian Space Agency mission (jointly operated by Microsat Systems Canada Inc. (formerly the Space Division of Dynacon Inc.), the University of Toronto Institute for Aerospace Studies - SpaceFlight Lab and the University of British Columbia, with the assistance of the University of Vienna), and on spectroscopic data from the David Dunlap Observatory, University of Toronto, and Las Campanas Observatory, Carnegie Institute Washington.

  17. The low-mass classic Algol-type binary UU Leo revisited

    NASA Astrophysics Data System (ADS)

    Yang, Yuan-Gui

    2013-12-01

    New multi-color photometry of the eclipsing binary UU Leo, acquired from 2010 to 2013, was carried out by using the 60-cm and 85-cm telescopes at the Xinglong station, which is administered by National Astronomical Observatories, Chinese Academy of Sciences. With the updated Wilson-Devinney code, the photometric solution was derived from BVR light curves. The results imply that UU Leo is a semi-detached Algol-type binary, with a mass ratio of q = 0.100(±0.002). The change in orbital period was reanalyzed based on all available eclipsing times. The O - C curve could be described by an upward parabola superimposed on a quasi-sinusoidal curve. The period and semi-amplitudes are Pmod = 54.5(±1.1) yr and A = 0.0273d(±0.0015d), which may be attributed to the light-time effect via the presence of an invisible third body. The long-term period increases at a rate of dP/dt = +4.64(±0.14) × 10-7d yr-1, which may be interpreted by the conserved mass being transferred from the secondary to the primary. With mass being transferred, the low-mass Algol-type binary UU Leo may evolve into a binary system with a main sequence star and a helium white dwarf.

  18. Eclipsing Binaries with the Kepler Mission

    NASA Astrophysics Data System (ADS)

    Prsa, Andrej; Kepler Eclipsing Binary Working Group

    2012-05-01

    Kepler has revolutionized the eclipsing binary field by providing us essentially uninterrupted data of unprecedented quality. Out of 160,000 targets, we detected over 2500 eclipsing binaries. These range in orbital periods from as short as 0.3 days, all the way to several years, and encompass stellar types across the H-R diagram. In this talk I will present the collaborative effort of the Kepler Eclipsing Binary Working Group to study and characterize these systems on a statistical level: their distribution in periods, galactic latitude, spectral type, fundamental stellar properties and multiplicity as evidenced by eclipse timing variations. I will further show the gems that have sprung from this sample, which were modeled and interpreted to reveal intrinsically pulsating components, runaway encounters with massive tertiaries, stellar objects that populate the lowest end of the main sequence and circumbinary planets. I will critically review and discuss the causes of data systematics and detrending, and introduce a novel algorithm to classify light curves into morphological types using Locally Linear Embedding. Finally, I will touch on the dark side of eclipsing binaries as the primary cause of false positives in extrasolar planet detections with Kepler.

  19. ROTATIONAL VELOCITIES OF INDIVIDUAL COMPONENTS IN VERY LOW MASS BINARIES

    SciTech Connect

    Konopacky, Q. M.; Macintosh, B. A.; Ghez, A. M.; Fabrycky, D. C.; White, R. J.; Barman, T. S.; Rice, E. L.; Hallinan, G.; Duchene, G. E-mail: konopacky@di.utoronto.ca E-mail: fabrycky@ucolick.org E-mail: barman@lowell.edu E-mail: gh@astro.caltech.edu

    2012-05-01

    We present rotational velocities for individual components of 11 very low mass (VLM) binaries with spectral types between M7 and L7.5. These results are based on observations taken with the near-infrared spectrograph, NIRSPEC, and the Keck II laser guide star adaptive optics system. We find that the observed sources tend to be rapid rotators (v sin i > 10 km s{sup -1}), consistent with previous seeing-limited measurements of VLM objects. The two sources with the largest v sin i, LP 349-25B and HD 130948C, are rotating at {approx}30% of their break-up speed, and are among the most rapidly rotating VLM objects known. Furthermore, five binary systems, all with orbital semimajor axes {approx}<3.5 AU, have component v sin i values that differ by greater than 3{sigma}. To bring the binary components with discrepant rotational velocities into agreement would require the rotational axes to be inclined with respect to each other, and that at least one component is inclined with respect to the orbital plane. Alternatively, each component could be rotating at a different rate, even though they have similar spectral types. Both differing rotational velocities and inclinations have implications for binary star formation and evolution. We also investigate possible dynamical evolution in the triple system HD 130948A-BC. The close binary brown dwarfs B and C have significantly different v sin i values. We demonstrate that components B and C could have been torqued into misalignment by the primary star, A, via orbital precession. Such a scenario can also be applied to another triple system in our sample, GJ 569A-Bab. Interactions such as these may play an important role in the dynamical evolution of VLM binaries. Finally, we note that two of the binaries with large differences in component v sin i, LP 349-25AB and 2MASS 0746+20AB, are also known radio sources.

  20. The Low-mass Astrometric Binary LSR 1610-0040

    NASA Astrophysics Data System (ADS)

    Koren, Seth C.; Blake, Cullen H.; Dahn, Conard C.; Harris, Hugh C.

    2016-03-01

    Even though it was discovered more than a decade ago, LSR 1610-0040 remains an enigma. This object has a peculiar spectrum that exhibits some features typically found in L subdwarfs, and others common in the spectra of more massive M dwarf stars. It is also a binary system with a known astrometric orbital solution. Given the available data, it remains a challenge to reconcile the observed properties of the combined light of LSR 1610-0040AB with current theoretical models of low-mass stars and brown dwarfs. We present the results of a joint fit to both astrometric and radial velocity measurements of this unresolved, low-mass binary. We find that the photocentric orbit has a period P=633.0+/- 1.7 days, somewhat longer than previous results, eccentricity of e=0.42+/- 0.03, and we estimate that the semimajor axis of the orbit of the primary is {a}1≈ 0.32 {{AU}}, consistent with previous results. While a complete characterization of the system is limited by our small number of radial velocity measurements, we establish a likely primary mass range of 0.09-0.10 {M}⊙ from photometric and color-magnitude data. For a primary mass in this range, the secondary is constrained to be 0.06-0.075 {M}⊙ , making a negligible contribution to the total I-band luminosity. This effectively rules out the possibility of the secondary being a compact object such as an old, low-mass white dwarf. Based on our analysis, we predict a likely angular separation at apoapsis comparable to the resolution limits of current high-resolution imaging systems. Measuring the angular separation of the A and B components would finally enable a full, unambiguous solution for the masses of the components of this system.

  1. THE RADIUS DISCREPANCY IN LOW-MASS STARS: SINGLE VERSUS BINARIES

    SciTech Connect

    Spada, F.; Demarque, P.; Kim, Y.-C.; Sills, A.

    2013-10-20

    A long-standing issue in the theory of low-mass stars is the discrepancy between predicted and observed radii and effective temperatures. In spite of the increasing availability of very precise radius determinations from eclipsing binaries and interferometric measurements of radii of single stars, there is no unanimous consensus on the extent (or even the existence) of the discrepancy and on its connection with other stellar properties (e.g., metallicity, magnetic activity). We investigate the radius discrepancy phenomenon using the best data currently available (accuracy ∼< 5%). We have constructed a grid of stellar models covering the entire range of low-mass stars (0.1-1.25 M{sub ☉}) and various choices of the metallicity and mixing length parameter, α. We used an improved version of the Yale Rotational stellar Evolution Code, implementing surface boundary conditions based on the most up-to-date PHOENIX atmosphere models. Our models are in good agreement with others in the literature and improve and extend the low mass end of the Yale-Yonsei isochrones. Our calculations include rotation-related quantities, such as moments of inertia and convective turnover timescales, useful in studies of magnetic activity and rotational evolution of solar-like stars. Consistent with previous works, we find that both binaries and single stars have radii inflated by about 3% with respect to the theoretical models; among binaries, the components of short orbital period systems are found to be the most deviant. We conclude that both binaries and single stars are comparably affected by the radius discrepancy phenomenon.

  2. Binaries in a medium of fast low-mass objects

    NASA Astrophysics Data System (ADS)

    Gould, Andrew

    1991-09-01

    The effect of dynamical friction on binaries in a medium of fast low-mass objects is determined. Results are obtained for an arbitrary particle distribution and for any value of Eb/m(sigma squared). Heggie's Law is confirmed and made more precise. The error in the calculation of Hills (1990) is traced to the very specialized and atypical choice of phase space for performing numerical simulations. The efforts of Bekenstein and Zamir (1990) are traced to inconsistencies in their use of the Vlasov equation. It is found that both the hardening and softening terms are generated by the action of objects with speeds relative to the binary center of mass which are greater than the orbital speed. For binaries at rest with respect to isotropic distribution, this contradicts a standard result, namely, that the viscous effect of fast objects vanishes identically. This paradox is resolved by deriving a more accurate dynamical friction formula. It is shown that a term which is usually dropped is in fact the dominant one.

  3. WISE Detection of Low-Mass X-ray Binaries

    NASA Astrophysics Data System (ADS)

    Wang, Zhongxiang

    2014-08-01

    I will report on the results from our search for the Wide-field Infrared Survey Explorer detection of the Galactic low-mass X-ray binaries. Among 187 catalogued binaries, we find 13 counterparts and two candidate counterparts. For the 13 counterparts, two (4 0614+091 and G 339-4) have already been confirmed by previous studies to have a jet and one (GR 1915+105) to have a candidate circumbinary disk, from which the detected infrared emission arose. Having collected the broad-band optical and near-infrared data in literature and constructed flux density spectra for the other 10 binaries, we identify that three (A0620-00, XTE J1118+480, and GX 1+4) are candidate circumbinary disk systems, four (Cen X-4, 4U 1700+24, 3A 1954+319, and Cyg X-2) had thermal emission from their companion stars, and three (Sco X-1, Her X-1, and Swift J1753.5-0127) are peculiar systems with the origin of their infrared emission rather uncertain. Discussion of the results and WISE counterparts' brightness distribution will be provided, which suggests that more than half of the LMXBs would have a jet, a circumbinary disk, or the both.

  4. 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.

  5. The low mass ratio contact binary system V728 Herculis

    NASA Astrophysics Data System (ADS)

    Erkan, N.; Ulaş, B.

    2016-07-01

    We present the orbital period study and the photometric analysis of the contact binary system V728 Her. Our orbital period analysis shows that the period of the system increases (dP / dt = 1.92 ×10-7 dyr-1) and the mass transfer rate from the less massive component to more massive one is 2.51 ×10-8 M⊙y-1 . In addition, an advanced sinusoidal variation in period can be attributed to the light-time effect by a tertiary component or the Applegate mechanism triggered by the secondary component. The simultaneous multicolor BVR light and radial velocity curves solution indicates that the physical parameters of the system are M1 = 1.8M⊙ , M2 = 0.28M⊙ , R1 = 1.87R⊙ , R2 = 0.82R⊙ , L1 = 5.9L⊙ , and L2 = 1.2L⊙ . We discuss the evolutionary status and conclude that V728 Her is a deep (f = 81%), low mass ratio (q = 0.16) contact binary system.

  6. KEPLER ECLIPSING BINARY STARS. II. 2165 ECLIPSING BINARIES IN THE SECOND DATA RELEASE

    SciTech Connect

    Slawson, Robert W.; Doyle, Laurance R.; Prsa, Andrej; Engle, Scott G.; Conroy, Kyle; Coughlin, Jared; Welsh, William F.; Orosz, Jerome A.; Gregg, Trevor A.; Fetherolf, Tara; Short, Donald R.; Windmiller, Gur; Rucker, Michael; Batalha, Natalie; Fabrycky, Daniel C.; Jenkins, Jon M.; Mullally, F.; Seader, Shawn E.

    2011-11-15

    The Kepler Mission provides nearly continuous monitoring of {approx}156,000 objects with unprecedented photometric precision. Coincident with the first data release, we presented a catalog of 1879 eclipsing binary systems identified within the 115 deg{sup 2} Kepler field of view (FOV). Here, we provide an updated catalog augmented with the second Kepler data release which increases the baseline nearly fourfold to 125 days. Three hundred and eighty-six new systems have been added, ephemerides and principal parameters have been recomputed. We have removed 42 previously cataloged systems that are now clearly recognized as short-period pulsating variables and another 58 blended systems where we have determined that the Kepler target object is not itself the eclipsing binary. A number of interesting objects are identified. We present several exemplary cases: four eclipsing binaries that exhibit extra (tertiary) eclipse events; and eight systems that show clear eclipse timing variations indicative of the presence of additional bodies bound in the system. We have updated the period and galactic latitude distribution diagrams. With these changes, the total number of identified eclipsing binary systems in the Kepler FOV has increased to 2165, 1.4% of the Kepler target stars. An online version of this catalog is maintained at http://keplerEBs.villanova.edu.

  7. Eclipsing Binary B-Star Mass Determinations

    NASA Astrophysics Data System (ADS)

    Townsend, Amanda; Eikenberry, Stephen S.

    2016-01-01

    B-stars in binary pairs provide a laboratory for key astrophysical measurements of massive stars, including key insights for the formation of compact objects (neutron stars and black holes). In their paper, Martayan et al (2004) find 23 Be binary star pairs in NGC2004 in the Large Magellanic Cloud, five of which are both eclipsing and spectroscopic binaries with archival data from VLT-Giraffe and photometric data from MACHO. By using the Wilson eclipsing binary code (e.g., Wilson, 1971), we can determine preliminary stellar masses of the binary components. We present the first results from this analysis. This study also serves as proof-of-concept for future observations with the Photonic Synthesis Telescope Array (Eikenberry et al., in prep) that we are currently building for low-cost, precision spectroscopic observations. With higher resolution and dedicated time for observations, we can follow-up observations of these Be stars as well as Be/X-ray binaries, for improved mass measurements of neutron stars and black holes and better constraints on their origin/formation.

  8. HIGH-PRECISION DYNAMICAL MASSES OF VERY LOW MASS BINARIES

    SciTech Connect

    Konopacky, Q. M.; Ghez, A. M.; McLean, I. S.; Barman, T. S.; Rice, E. L.; Bailey, J. I.; White, R. J.; Duchene, G. E-mail: ghez@astro.ucla.ed E-mail: barman@lowell.ed E-mail: white@chara.gsu.ed

    2010-03-10

    We present the results of a three year monitoring program of a sample of very low mass (VLM) field binaries using both astrometric and spectroscopic data obtained in conjunction with the laser guide star adaptive optics system on the W. M. Keck II 10 m telescope. Among the 24 systems studied, 15 have undergone sufficient orbital motion, allowing us to derive their relative orbital parameters and hence their total system mass. These measurements more than double the number of mass measurements for VLM objects, and include the most precise mass measurement to date (<2%). Among the 11 systems with both astrometric and spectroscopic measurements, six have sufficient radial velocity variations to allow us to obtain individual component masses. This is the first derivation of the component masses for five of these systems. Altogether, the orbital solutions of these low mass systems show a correlation between eccentricity and orbital period, consistent with their higher mass counterparts. In our primary analysis, we find that there are systematic discrepancies between our dynamical mass measurements and the predictions of theoretical evolutionary models (TUCSON and LYON) with both models either underpredicting or overpredicting the most precisely determined dynamical masses. These discrepancies are a function of spectral type, with late-M through mid-L systems tending to have their masses underpredicted, while one T-type system has its mass overpredicted. These discrepancies imply that either the temperatures predicted by evolutionary and atmosphere models are inconsistent for an object of a given mass, or the mass-radius relationship or cooling timescales predicted by the evolutionary models are incorrect. If these spectral-type trends are correct and hold into the planetary mass regime, the implication is that the masses of directly imaged extrasolar planets are overpredicted by the evolutionary models.

  9. Relativistic apsidal motion in eccentric eclipsing binaries

    NASA Astrophysics Data System (ADS)

    Wolf, M.; Claret, A.; Kotková, L.; Kučáková, H.; Kocián, R.; Brát, L.; Svoboda, P.; Šmelcer, L.

    2010-01-01

    Context. The study of apsidal motion in detached eclipsing binary systems is known to be an important source of information about stellar internal structure as well as the possibility of verifying of General Relativity outside the Solar System. Aims: As part of the long-term Ondřejov and Ostrava observational projects, we aim to measure precise times of minima for eccentric eclipsing binaries, needed for the accurate determination of apsidal motion, providing a suitable test of the effects of General Relativity. Methods: About seventy new times of minimum light recorded with photoelectric or CCD photometers were obtained for ten eccentric-orbit eclipsing binaries with significant relativistic apsidal motion. Their O-C diagrams were analysed using all reliable timings found in the literature, and new or improved elements of apsidal motion were obtained. Results: We confirm very long periods of apsidal motion for all systems. For BF Dra and V1094 Tau, we present the first apsidal-motion solution. The relativistic effects are dominant, representing up to 100% of the total observable apsidal-motion rate in several systems. The theoretical and observed values of the internal structure constant k 2 were compared for systems with lower relativistic contribution. Using the light-time effect solution, we predict a faint third component for V1094 Tau orbiting with a short period of about 8 years. Partly based on photoelectric observations secured at the Hvar Observatory, Faculty of Geodesy, Zagreb, Croatia, in October 2008.

  10. Apsidal motion in eclipsing binary GG Orionis

    NASA Astrophysics Data System (ADS)

    Yilan, E.; Bulut, I.

    2016-03-01

    The study of apsidal motion in binary stars with eccentric orbit is well known as an important source of information for the stellar internal structure as well as the possibility of verification of general relativity. In this study, the apsidal motion of the eccentric eclipsing binary GG Ori (P = 6.631 days, e = 0.22) has been analyzed using the times of minimum light taken from the literature and databases and the elements of apsidal motion have been computed. The method described by Giménez and García-Pelayo (1983) has been used for the apsidal motion analysis.

  11. A Unified Model of Low Mass X-ray Binaries

    NASA Astrophysics Data System (ADS)

    Balucinska-Church, M.; Church, M.

    2014-07-01

    We present a unified physical model of Low Mass X-ray Binaries explaining the basic Atoll and Z-track types of source. In all LMXB with luminosity above 1-2.10^{37} erg/s, we have a new fundamental result that the temperature of the Comptonizing ADC corona equals that of the neutron star, i.e. there is thermal equilibrium. This equilibrium explains the properties of the basic Banana State of Atoll sources. Below this luminosity, equilibrium breaks down, T_ADC rising towards 100 keV by an unknown heating mechanism, explaining the Island State. Above 5.10^{37} erg/s flaring begins in the GX-Atolls which we show is unstable nuclear burning. Above 1.10^{38} erg/s, LMXB are seen as Z-track sources. Flaring in these and the GX-Atolls occurs when the mass accretion rate to the neutron star falls to the critical value for unstable nuclear burning on the star. Below 2.10^{37} erg/s, a different unstable burning: X-ray bursting, takes over. We show that the Normal Branch of the Z-track consists simply of increasing mass accretion rate, as is the Banana State in Atolls. In the Horizontal Branch, a measured, strongly increasing radiation pressure of the neutron star disrupts the inner disk launching the relativistic jets seen on this branch.

  12. Probing Binary Formation Theories with the Largest Catalog of Ultra-wide, Low-mass Binaries

    NASA Astrophysics Data System (ADS)

    Dhital, Saurav; West, Andrew A.; Stassun, Keivan G.; Law, Nicholas M.; Massey, Angela P.

    2013-07-01

    We present results from the Sloan Low-mass Wide Pairs of Kinematically Equivalent Stars (SLoWPoKES) catalogs of ultra-wide (10^3-5.5 AU), low-mass (K5-M7) visual binaries, comprising of over 100,000 pairs. We constructed a Galactic model, based on empirical stellar number density and 3D velocity distributions, to select bona fide pairs with probability of chance alignment ≤5%, making SLoWPoKES an efficient sample for followup observations. The diversity - in mass, metallicity, age, and evolutionary states - of SLoWPoKES pairs makes it a valuable resource of coeval laboratories to examine and constrain the physical properties of low-mass stars. SLoWPoKES appears to contain two populations of wide binaries, with a break at projected physical separation of 0.1 pc, suggesting that they were formed via different mechanisms or have significantly different dynamical history. Followup high-resolution imaging has revealed that the multiplicity in "individual" stars in the ultra-wide binaries (higher-order multiplicity) is significantly higher than in tighter binaries or low-mass field stars. This is consistent with the premise that ultra-wide systems are the result of dynamical widening via transfer of angular momentum from the outer orbit to the inner orbit, followed by dissipation via interactions with Galactic tide and giant molecular clouds. Indeed, we find that the higher-order multiplicity decreases with Galactic height, evidence that they are destroyed over time. This bimodality, however, is also consistent with recent theoretical predictions, which show that the ultra-wide binaries are not formed primordially but during dissipation of star clusters. Our data do not rule out either scenario but indicate neither mechanism can form all of the observed wide binaries. We conclude that multiple processes, not all of which are primordial, are likely responsible for the observed distribution of stellar binaries.

  13. Kepler Eclipsing Binary Stars. VIII. Identification of False Positive Eclipsing Binaries and Re-extraction of New Light Curves

    NASA Astrophysics Data System (ADS)

    Abdul-Masih, Michael; Prša, Andrej; Conroy, Kyle; Bloemen, Steven; Boyajian, Tabetha; Doyle, Laurance R.; Johnston, Cole; Kostov, Veselin; Latham, David W.; Matijevič, Gal; Shporer, Avi; Southworth, John

    2016-04-01

    The Kepler mission has provided unprecedented, nearly continuous photometric data of ∼200,000 objects in the ∼105 deg2 field of view (FOV) from the beginning of science operations in May of 2009 until the loss of the second reaction wheel in May of 2013. The Kepler Eclipsing Binary Catalog contains information including but not limited to ephemerides, stellar parameters, and analytical approximation fits for every known eclipsing binary system in the Kepler FOV. Using target pixel level data collected from Kepler in conjunction with the Kepler Eclipsing Binary Catalog, we identify false positives among eclipsing binaries, i.e., targets that are not eclipsing binaries themselves, but are instead contaminated by eclipsing binary sources nearby on the sky and show eclipsing binary signatures in their light curves. We present methods for identifying these false positives and for extracting new light curves for the true source of the observed binary signal. For each source, we extract three separate light curves for each quarter of available data by optimizing the signal-to-noise ratio, the relative percent eclipse depth, and the flux eclipse depth. We present 289 new eclipsing binaries in the Kepler FOV that were not targets for observation, and these have been added to the catalog. An online version of this catalog with downloadable content and visualization tools is maintained at http://keplerEBs.villanova.edu.

  14. Phenomenological modelling of eclipsing binary stars

    NASA Astrophysics Data System (ADS)

    Andronov, I. L.; Tkachenko, M. G.; Chinarova, L. L.

    2016-03-01

    We review the method NAV ("New Algol Variable") first introduced in (2012Ap.....55..536A) which uses the locally-dependent shapes of eclipses in an addition to the trigonometric polynomial of the second order (which typically describes the "out-of-eclipse" part of the light curve with effects of reflection, ellipticity and O'Connell). Eclipsing binary stars are believed to show distinct eclipses only if belonging to the EA (Algol) type. With a decreasing eclipse width, the statistically optimal value of the trigonometric polynomial s(2003ASPC..292..391A) drastically increases from ~2 for elliptic (EL) variables without eclipses, ~6-8 for EW and up to ~30-50 for some EA with narrow eclipses. In this case of large number of parameters, the smoothing curve becomes very noisy and apparent waves (the Gibbs phenomenon) may be seen. The NAV set of the parameters may be used for classification in the GCVS, VSX and similar catalogs. The maximal number of parameters is m=12, which corresponds to s=5, if correcting both the period and the initial epoch. We have applied the method to few stars, also in a case of multi-color photometry (2015JASS...32..127A), when it is possible to use the phenomenological parameters from the NAV fit to estimate physical parameters using statistical dependencies. For the one-color observations, one may estimate the ratio of the surface brightnesses of the components. We compiled a catalog of phenomenological characteristics based on published observations. We conclude that the NAV approximation is better than the TP one even for the case of EW-type stars with much wider eclipses. It may also be used to determine timings (see 2005ASPC..335...37A for a review of methods) or to determine parameters in the case of variable period, using a complete light curve modeling the phase variations. The method is illustrated on 2MASS J11080447-6143290 (EA-type), USNO-B1.0 1265-0306001 and USNO-B1.01266-0313413 (EW-type) and compared to various other methods

  15. Double riches: asteroseismology in eclipsing binaries

    NASA Astrophysics Data System (ADS)

    Southworth, John

    2015-08-01

    Abstract: Eclipsing binaries are a cornerstone of modern astrophysics: their components are the only stars beyond the solar neighbourhood whose masses and radii can be measured directly and to high precision. This makes them critical objects for testing and facilitating the improvement of theoretical stellar models. Asteroseismology is another window on the properties of stars: pulsation frequencies and amplitudes carry information on their bulk properties and interior structure. The combination of asteroseismology and eclipses holds the promise of determining the pulsation properties of stars of precisely known mass and radius, providing an unprecedented test of stellar models. I review what can be learnt, how the measurements are made, and possible sources of the necessary observational data. Work so far has primarily relied on space-based photometry, and the future holds the tantalizing prospect of results from K2, BRITE, CHEOPS, TESS and PLATO.

  16. Properties of an eclipsing double white dwarf binary NLTT 11748

    SciTech Connect

    Kaplan, David L.; Walker, Arielle N.; Marsh, Thomas R.; Bours, Madelon C. P.; Breedt, Elmé; Bildsten, Lars; Copperwheat, Chris M.; Dhillon, Vik S.; Littlefair, Stuart P.; Howell, Steve B.; Shporer, Avi; Steinfadt, Justin D. 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 eclipses 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).

  17. Apsidal motion in five eccentric eclipsing binaries

    NASA Astrophysics Data System (ADS)

    Wolf, M.; Zasche, P.; Kučáková, H.; Lehký, M.; Svoboda, P.; Šmelcer, L.; Zejda, M.

    2013-01-01

    Aims: As part of the long-term Ondřejov and Ostrava observational projects, we aim to measure the precise times of minimum light for eccentric eclipsing binaries, needed for accurate determination of apsidal motion. Over fifty new times of minimum light recorded with CCD photometers were obtained for five early-type and eccentric-orbit eclipsing binaries: V785 Cas (P = 2.d70, e = 0.09), V821 Cas (1.d77, 0.14), V796 Cyg (1.d48, 0.07), V398 Lac (5.d41, 0.23), and V871 Per (3.d02, 0.24). Methods: O-C diagrams of binaries were analysed using all reliable timings found in the literature, and new elements of apsidal motion were obtained. Results: We derived for the first time or improved the relatively short periods of apsidal motion of about 83, 140, 33, 440, and 70 years for V785 Cas, V821 Cas, V796 Cyg, V398 Lac, and V871 Per, respectively. The internal structure constants, log k2, for V821 Cas and V398 Lac are then found to be -2.70 and -2.35, under the assumption that the component stars rotate pseudosynchronously. The relativistic effects are weak, up to 7% of the total apsidal motion rate.

  18. Propertires of K/M Dwarf Eclipsing Binaries

    NASA Astrophysics Data System (ADS)

    Riddle, Andrew; Kraus, Adam L.

    2016-01-01

    Stellar models of low-mass stars (M < 0.8 M_Sun) have been found to be in disagreement with observed properties, the observed radii being larger and the observed temperatures being lower. To characterize this discrepancy and search for possible confounding parameters, we are observing a sample of low-mass eclipsing binaries using the McDonald 2.7-m telescope and archival Keck data for spectroscopic observations as well as the 0.8-m telescope at McDonald. This study will greatly increase the number of well-characterized low-mass stars, allowing for a better understanding of how fundamental stellar parameters (T_eff, R_*, M_*, abundances, activity, luminosity, etc.) depend on one another. We are using IGRINS, a high resolution (R=40,000) IR (H+K) spectrograph on the McDonald 2.7-m, to measure T_eff and abundances of the sample to a higher precision than previously capable. Relationships between the stellar parameters could reveal the influence of extra parameters on the mass-radius relation, indicating the additional physics that must be added to stellar evolutionary models to bring them into agreement with observations.

  19. A Photometric Study of ASAS J184708-3340.2: an Eclipsing Binary with Total Eclipses

    NASA Astrophysics Data System (ADS)

    Berrington, R. C.; Tuhey, E. M.

    2015-06-01

    We present new multi-band differential aperture photometry of the eclipsing variable star ASAS J184708-3340.2. The light curves are analyzed with the Wilson-Devinney model to determine best-fit stellar models. Our models show that ASAS J184708-3340.2 is consistent with an overcontact eclipsing binary (W Ursae Majoris) system with total eclipses.

  20. Deep, Low Mass Ratio Overcontact Binary Systems. XIII. DZ Piscium with Intrinsic Light Variability

    NASA Astrophysics Data System (ADS)

    Yang, Y.-G.; Qian, S.-B.; Zhang, L.-Y.; Dai, H.-F.; Soonthornthum, B.

    2013-08-01

    New multi-color photometry for the eclipsing binary DZ Psc was performed in 2011 and 2012 using the 85 cm telescope at the Xinglong Station of the National Astronomical Observatories of China. Using the updated Wilson-Devinney (W-D) code, we deduced two sets of photometric solutions. The overcontact degree is f = 89.7(± 1.0)%, identifying DZ Psc as a deep, low mass ratio overcontact binary. The asymmetric light curves (i.e., LC2 in 2012) were modeled by a hot spot on the primary star. Based on all of the available light minimum times, we discovered that the orbital period of DZ Psc may be undergoing a secular period increase with a cyclic variation. The modulated period and semi-amplitude of this oscillation are P mod = 11.89(± 0.19) yr and A = 0.0064(± 0.0006) days, which may be possibly attributed to either cyclic magnetic activity or light-time effect due to the third body. The long-term period increases at a rate of dP/dt=+7.43(+/- 0.17)\\times 10^{-7}{\\,days\\, yr^{-1}}, which may be interpreted as conserved mass transfer from the less massive component to the more massive one. With mass transferring, DZ Psc will finally merge into a rapid-rotation single star when J spin/J orb > 1/3.

  1. DEEP, LOW MASS RATIO OVERCONTACT BINARY SYSTEMS. XIII. DZ PISCIUM WITH INTRINSIC LIGHT VARIABILITY

    SciTech Connect

    Yang, Y.-G.; Dai, H.-F.; Qian, S.-B.; Soonthornthum, B. E-mail: qsb@ynao.ac.cn

    2013-08-01

    New multi-color photometry for the eclipsing binary DZ Psc was performed in 2011 and 2012 using the 85 cm telescope at the Xinglong Station of the National Astronomical Observatories of China. Using the updated Wilson-Devinney (W-D) code, we deduced two sets of photometric solutions. The overcontact degree is f = 89.7({+-} 1.0)%, identifying DZ Psc as a deep, low mass ratio overcontact binary. The asymmetric light curves (i.e., LC{sub 2} in 2012) were modeled by a hot spot on the primary star. Based on all of the available light minimum times, we discovered that the orbital period of DZ Psc may be undergoing a secular period increase with a cyclic variation. The modulated period and semi-amplitude of this oscillation are P{sub mod} = 11.89({+-} 0.19) yr and A = 0.0064({+-} 0.0006) days, which may be possibly attributed to either cyclic magnetic activity or light-time effect due to the third body. The long-term period increases at a rate of dP/dt=+7.43({+-}0.17) Multiplication-Sign 10{sup -7} days yr{sup -1}, which may be interpreted as conserved mass transfer from the less massive component to the more massive one. With mass transferring, DZ Psc will finally merge into a rapid-rotation single star when J{sub spin}/J{sub orb} > 1/3.

  2. Three eclipsing white dwarf plus main sequence binaries from SDSS

    NASA Astrophysics Data System (ADS)

    Pyrzas, S.; Gänsicke, B. T.; Marsh, T. R.; Aungwerojwit, A.; Rebassa-Mansergas, A.; Southworth, J.; Rodríguez-Gil, P.; Schreiber, M. R.; Koester, D.

    2009-06-01

    We identify SDSS 0110+1326, SDSS 0303+0054 and SDSS 1435+3733 as three eclipsing white dwarf plus main sequence binaries from the Sloan Digital Sky Survey, and report on their follow-up observations. Orbital periods for the three systems are established through multi-season photometry. Time-resolved spectroscopic observations lead to the determination of the radial velocities of the secondary stars. A decomposition technique of the SDSS spectra is used to estimate the surface gravities and effective temperatures of the white dwarfs, as well as the spectral types of the secondaries. By combining the constraints from the spectral decomposition, the radial velocity data and the modeling of the systems' light curves, we determine the physical parameters of the stellar components. Two of the white dwarfs are of low mass (Mwd ~ 0.4 Modot), while the third white dwarf is unusually massive (MWD ~ 0.8-0.9 Modot) for a post-common envelope system.

  3. The Reflection Effect in Eclipsing Binaries

    NASA Astrophysics Data System (ADS)

    Gropp, Jeffrey D.; Prsa, Andrej

    2016-01-01

    Using a database of eclipsing binaries (EBs) from the Kepler space telescope, we identified star systems which displayed characteristics corresponding to the reflection effect. The reflection effect is the brightening of one star due to irradiation by its companion. We found 40 candidates amongst the nearly 2,800 EBs in the database. We analyze these candidates and derive parameters and properties of each system using the PHOEBE modeling program. We examine each model fit using probabilistic inference in order to statistically evaluate the best fit model. The model critically tests the reflection effect and provides physical constraints on the principal parameters.

  4. DEEP, LOW MASS RATIO OVERCONTACT BINARY SYSTEMS. XI. V1191 CYGNI

    SciTech Connect

    Zhu, L. Y.; Qian, S. B.; He, J. J.; Liu, L.

    2011-10-15

    Complete CCD photometric light curves in BV(RI){sub c} bands obtained on one night in 2009 for the short-period close-binary system V1191 Cygni are presented. A new photometric analysis with the 2003 version of the Wilson-Van Hamme code shows that V1191 Cyg is a W-type overcontact binary system and suggests that it has a high degree of overcontact (f = 68.6%) with very low mass ratio, implying that it is at the late stage of overcontact evolution. The absolute parameters of V1191 Cyg are derived using spectroscopic and photometric solutions. Combining new determined times of light minimum with others published in the literature, the period change of the binary star is investigated. A periodic variation, with a period of 26.7 years and an amplitude of 0.023 days, was discovered to be superimposed on a long-term period increase (dP/dt = +4.5({+-} 0.1) x 10{sup -7} days yr{sup -1}). The cyclic period oscillation may be caused by the magnetic activity cycles of either of the components or the light-time effect due to the presence of a third body with a mass of m{sub 3} = 0.77 M{sub sun} and an orbital radius of a{sub 3} = 7.6 AU, when this body is coplanar to the orbit of the eclipsing pair. The secular orbital period increase can be interpreted as a mass transfer from the less massive component to the more massive one. With the period increases, V1191 Cyg will evolve from its present low mass ratio, high filled overcontact state to a rapidly rotating single star when its orbital angular momentum is less than three times the total spin angular momentum. V1191 Cyg is too blue for its orbital period and it is an unusual W-type overcontact system with such a low mass ratio and high fill-out overcontact configuration, which is worth monitoring continuously in the future.

  5. Studies of Long Period Eclipsing Binaries

    NASA Astrophysics Data System (ADS)

    Ratajczak, M.; Hełminiak, K. G.; Konacki, M.

    2015-07-01

    The survey of long period eclipsing binaries from the All Sky Automated Survey (ASAS) catalog aims at searching for and characterizing subgiants and red giants in double-lined detached binary systems. Absolute physical and orbital parameters are presented based on radial velocities from high-quality optical spectra obtained with the following telescope/instrument combinations: 8.2 m Subaru/HDS, ESO 3.6 m/HARPS, 1.9 m Radcliffe/GIRAFFE, CTIO 1.5 m/CHIRON, and 1.2 m Euler/CORALIE. Photometric data from ASAS, SuperWASP, and the Solaris Project were also used. We discuss the derived uncertainties for the individual masses and radii of the components (better than 3% for several systems), as well as results from the spectral analysis performed for components of systems whose spectra we disentangled.

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

    SciTech Connect

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

    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 levels in and out of eclipse. We identify 236 systems for which we find a timing variation signal compatible with the presence of a third body. These are modeled for the light travel time effect and the basic properties of the third body are derived. This study complements J. A. Orosz et al. (in preparation), which focuses on eclipse timing variations of longer period binaries with flat out-of-eclipse regions. Together, these two papers provide comprehensive eclipse timings for all binaries in the Kepler Eclipsing Binary Catalog, as an ongoing resource freely accessible online to the community.

  7. Properties of eclipsing binaries from all-sky surveys - I. Detached eclipsing binaries in ASAS, NSVS, and LINEAR

    NASA Astrophysics Data System (ADS)

    Lee ( ), Chien-Hsiu

    2015-11-01

    Eclipsing binaries provide a unique opportunity to measure fundamental properties of stars. With the advent of all-sky surveys, thousands of eclipsing binaries have been reported, yet their light curves are not fully exploited. The goal of this work is to make use of the eclipsing binary light curves delivered by all-sky surveys. We attempt to extract physical parameters of the binary systems from their light curves and colour. Inspired by the work of Devor et al., we use the Detached Eclipsing Binary Light curve fitter (DEBIL) and the Method for Eclipsing Component Identification (MECI) to derive basic properties of the binary systems reported by the All Sky Automated Survey, the Northern Sky Variability Survey, and the Lincoln Near Earth Asteroids Research. We derive the mass, fractional radius, and age for 783 binary systems. We report a subsample of eccentric systems and compare their properties to the tidal circularization theory. With MECI, we are able to estimate the distance of the eclipsing binary systems and use them to probe the structure of the Milky Way. Following the approach of Devor et al., we demonstrate that DEBIL and MECI are instrumental to investigate eclipsing binary light curves in the era of all-sky surveys, and provide estimates of stellar parameters of both binary components without spectroscopic information.

  8. A New Eclipsing Binary Discovered in a Crowded Star Field

    NASA Astrophysics Data System (ADS)

    Larson, Jessica A.; Ranquist, E.; Hernandez, A.; Stoker, E.; Gaillard, C.

    2013-06-01

    Using the 0.9 meter telescope on West Mountain to follow-up possible transiting planets with ground based photometry, we discovered a previously unknown eclipsing binary system. This eclipsing binary is located in a crowded star field and so could not be reduced using photometry. In order to figure out which object in our field of view is the eclipsing binary, we learned how to use DAO phot. By using DAO phot we hope to be able to learn more about the individual stars that make up the binary system and their parameters.

  9. The Behavior of Accretion Disks in Low Mass X-ray Binaries: Disk Winds and Alpha Model

    NASA Astrophysics Data System (ADS)

    Bayless, Amanda J.

    2010-01-01

    This dissertation presents research on two low mass X-ray binaries. The eclipsing low-mass X-ray binary 4U 1822-371 is the prototypical accretion disk corona (ADC) system. We have obtained new time-resolved UV spectroscopy with the ACS/SBC on the Hubble Space Telescope and new V- and J-band photometry with the 1.3-m SMARTS telescope at CTIO. We show that the accretion disk in the system has a strong wind with projected velocities up to 4000 km/s as determined from the Doppler width of the C IV emission line. The broad and shallow eclipse indicates that the disk has a vertically-extended, optically-thick component at optical wavelengths. This component extends almost to the edge of the disk and has a height equal to 50% of the disk radius. As it has a low brightness temperature, we identify it as the optically-thick base of the disk wind. V1408 Aql (=4U 1957+115) is a low mass X-ray binary which continues to be a black hole candidate. We have new photometric data of this system from the Otto Struve 2.1-m telescope's high speed CCD photometer at McDonald Observatory. The light curve is largely sinusoidal which we model with two components: a constant light source from the disk and a sinusoidal modulation at the orbital period from the irradiated face of the companion star. This is a radical re-interpretation of the orbital light curve. We do not require a large or asymmetric disk rim to account for the modulation in the light curve. Thus, the orbital inclination is unconstrained in our new model, removing the foundation for any claims of the compact object being a black hole.

  10. Photometric study of an eclipsing binary in Praesepe

    NASA Astrophysics Data System (ADS)

    Shanti Priya, Devarapalli; Sriram, Kandulapati; Vivekananda Rao, Pasagada

    2013-04-01

    We present CCD photometric observations of an eclipsing binary in the direction of the open cluster Praesepe using the 2 m telescope at IUCAA Girawali Observatory, India. Though the system was classified as an eclipsing binary by Pepper et al., detailed investigations have been lacking. The photometric solutions using the Wilson-Devinney code suggest that it is a W-type W UMa system and, interestingly, the system parameters are similar to another contact binary system SW Lac.

  11. The hot subdwarf in the eclipsing binary HD 185510

    NASA Technical Reports Server (NTRS)

    Jeffery, C. S.; Simon, Theodore; Evans, T. L.

    1992-01-01

    High-resolution spectroscopic measurements of radial velocity are employed to characterize the eclipsing binary HD 185510 in terms of masses and evolutionary status. The IUE is used to obtain the radial velocities which indicate a large mass ratio Mp/Ms of 7.45 +/- 0.15, and Teff is given at 25,000 +/- 1000 K based on Ly alpha and UV spectrophotometry. Photometric observations are used to give an orbital inclination of between 90 and 70 deg inclusive, leading to masses of 0.31-0.37 and 2.3-2.8 solar mass for the hot star and the K star, respectively. The surface gravity of HD 185510B is shown to be higher than those values for sdB stars suggesting that the object is a low-mass white dwarf that has not reached its fully degenerate configuration. The object is theorized to be a low-mass helium main-sequence star or a nascent helium degenerate in a post-Algol system.

  12. The Kepler Mission and Eclipsing Binaries

    NASA Technical Reports Server (NTRS)

    Koch, David; Borucki, William; Lissauer, J.; Basri, Gibor; Brown, Timothy; Caldwell, Douglas; Cochran, William; Jenkins, Jon; Dunham, Edward; Gautier, Nick

    2006-01-01

    The Kepler Mission is a photometric mission with a precision of 14 ppm (at R=12) that is designed to continuously observe a single field of view (FOV) of greater 100 sq deg in the Cygnus-Lyra region for four or more years. The primary goal of the mission is to monitor greater than 100,000 stars for transits of Earth-size and smaller planets in the habitable zone of solar-like stars. In the process, many eclipsing binaries (EB) will also be detected and light curves produced. To enhance and optimize the mission results, the stellar characteristics for all the stars in the FOV with R less than 16 will have been determined prior to launch. As part of the verification process, stars with transit candidates will have radial velocity follow-up observations performed to determine the component masses and thereby separate eclipses caused by stellar companions from transits caused by planets. The result will be a rich database on EBs. The community will have access to the archive for further analysis, such as, for EB modeling of the high-precision light curves. A guest observer program is also planned to allow for photometric observations of objects not on the target list but within the FOV, since only the pixels of interest from those stars monitored will be transmitted to the ground.

  13. Deep, Low Mass Ratio Overcontact Binary Systems. V. The Lowest Mass Ratio Binary V857 Herculis

    NASA Astrophysics Data System (ADS)

    Qian, S.-B.; Zhu, L.-Y.; Soonthornthum, B.; Yuan, J.-Z.; Yang, Y.-G.; He, J.-J.

    2005-09-01

    Charge-coupled device (CCD) photometric light curves in the B, V, and R bands of the complete eclipsing binary star V857 Her are presented. It is shown that the light curves of the W UMa-type binary are symmetric and of A type according to Binnendijk's classification. Our four epochs of light minimum along with others compiled from the literature were used to revise the period and study the period change. Weak evidence indicates that the orbital period of V857 Her may show a continuous increase at a rate of dP/dt=+2.90×10-7 days yr-1. The photometric parameters of the system were determined with the 2003 version of the Wilson-Devinney code. It is shown that V857 Her is a deep overcontact binary system with f=83.8%+/-5.1%. The derived mass ratio of q=0.06532+/-0.0002 suggests that it has the lowest mass ratio among overcontact binary systems. As the orbital period increases, the decrease of the mass ratio will cause it to evolve into a single rapidly rotating star when it meets the more familiar criterion that the orbital angular momentum be less than 3 times the total spin angular momentum. To understand the evolutionary state of the system, long-term photometric monitoring and spectroscopic observations will be required.

  14. B-type stars in eclipsing binaries

    NASA Astrophysics Data System (ADS)

    Ratajczak, Milena; Pigulski, Andrzej

    2016-07-01

    B-type stars in eclipsing binary systems are unique astrophysical tools to test several aspects of stellar evolution. Such objects can be used e.g. to determine the masses of Beta Cephei variable stars, as well as help to place tighter constraints on the value of the convective core overshooting parameter α. Both precise photometry and high-resolution spectroscopy with high SNR are required to achieve these goals, but since many of the targets are bright enough, the challenge is fair. Following this assumption, we shall explain how we plan to examine both the aforementioned aspects of stellar evolution using observations of B-type stars obtained with a wide range of spectrographs, as well as BRITE-Constellation satellites.

  15. The reflection effect in eclipsing binary systems

    NASA Astrophysics Data System (ADS)

    Vaz, L. P. R.

    1985-07-01

    The weakest point in the modern models of eclipsing binary systems (EBS) is the treatment given to the effects of mutual irradiation. In this review, which does not have a similar one in the literature, an attempt is made to collect all the work done on the irradiation problem until the middle of 1984, in order to make possible an evaluation of the present status of this problem. Special emphasis is given to the applicability of the results to the analysis of EBS. The treatment given to the effect by the early studies, as well as by practically all the modern models of EBS, is described, and special attention is given to works analysing the problem using stellar model atmospheres. It turns out that the effect is more complex than suspected earlier, but that significant progress has been made recently.

  16. Evolution of Intermediate and Low Mass Binary Systems

    SciTech Connect

    Eggleton, P P

    2005-10-25

    There are a number of binaries, fairly wide and with one or even two evolved giant components, that do not agree very well with conventional stellar evolution: the secondaries are substantially larger (oversized) than they should be because their masses are quite low compared with the primaries. I discuss the possibility that these binaries are former triples, in which a merger has occurred fairly recently in a short-period binary sub-component. Some mergers are expected, and may follow a phase of contact evolution. I suggest that in contact there is substantial transfer of luminosity between the components due to differential rotation, of the character observed by helioseismology in the Sun's surface convection zone.

  17. Evolution of Very Close Binaries of Low Mass

    SciTech Connect

    Eggleton, P

    2009-07-17

    Binaries of low total mass (say 1-3 M{sub {circle_dot}}) and very short period (say {approx}< 4 d) are subject to a number of evolutionary processes, such as nuclear evolution, Roche-Lobe overflow, mass loss by stellar wind enhanced by rapid rotation, angular momentum loss by stellar wind with magnetic braking and tidal friction, mass transfer in contact (potentially in either direction), and heat transport from one component to the other during contact. Unfortunately all of these phenomena can be expected to occur on something like the same timescale. This makes it especially difficult to tie a particular system to a particular set of evolutionary processes. Theory suggests that very close binaries should appear in four morphological forms: detached binaries, semidetached binaries in which the more massive component is the one that fills its Roche lobe (reverse Algols), semidetached binaries in which the less massive component is the one that fills its Roche lobe (normal Algols), and contact, or, as some would say, overcontact binaries, where both components overfill their Roche lobes up to the same equipotential surface. This is not to say that perhaps some other configuration may be important, but I am not sure that any has yet been put forward that is incontrovertible. I have developed an evolutionary code in which the two components are solved simultaneously, and subject in principle to all six of the processes in the first paragraph. All four morphological forms are achievable by the code, as the physics demands. The code is still preliminary, partly at least because of the difficulty of quantifying all six processes. I will illustrate some possibly peculiar evolutionary scenarios that can emerge; but I will mainly argue, on the basis of observed data from a variety of systems, that it is indeed necessary to include all these processes, and not, for example, to ignore mass loss by stellar wind by claiming that it cannot be strong enough to be significant.

  18. CCD Photometry of Low Mass Ratio Contact Binary FP Boo - IV

    NASA Astrophysics Data System (ADS)

    Oh, Kyu-Dong; Lee, Woo-Baik

    2009-03-01

    We present new B, V, and R CCD photometric light curves for the low mass ratio contact binay FP Boo. A new photometric solution and absolute physical dimensions of the system were derived by applying the Wilson-Devinney program to our observed light curves and to previously published Rucinski et al.'s radial velocity curves. From the H-R diagram of 24 low mass ratio contact binary system including FP Boo, the evolutionary stage of FP Boo was found to coincide with those of the general low mass ratio contact binary systems. The light curves obtained in this season show a small asymmetry in their shapes.

  19. Precise Orbital Solutions for KEPLER Eclipsing Binaries of W UMa Type Showing Total Eclipses

    NASA Astrophysics Data System (ADS)

    Şenavcı, H. V.; Doǧruel, M. B.; Nelson, R. H.; Yılmaz, M.; Selam, S. O.

    2016-09-01

    We aim to discover the accuracy of photometric mass ratios (q ph) determined for eclipsing binary stars, in the case of the system having at least one `flat bottom' as a minimum profile, as well as the accuracy of data used in that sense. Within this context, we present the results of two-dimensional grid search (q - i) for some W UMa-type eclipsing binaries showing total eclipses, based on the high precision photometric data provided by the KEPLER Mission. The radial velocity data obtained for KIC10618253 in this study, enables us to compare both q ph and the corresponding spectroscopic mass ratio (q sp) values. The results indicate that the high precision photometric data for overcontact eclipsing binaries showing total eclipses allow us to obtain the photometric mass ratios as accurate as the spectroscopic values.

  20. MICROLENSING DISCOVERY OF A POPULATION OF VERY TIGHT, VERY LOW MASS BINARY BROWN DWARFS

    SciTech Connect

    Choi, J.-Y.; Han, C.; Udalski, A.; Sumi, T.; Gaudi, B. S.; Gould, A.; Bennett, D. P.; Dominik, M.; Beaulieu, J.-P.; Tsapras, Y.; Bozza, V.; Abe, F.; Furusawa, K.; Itow, Y.; Bond, I. A.; Ling, C. H.; Botzler, C. S.; Freeman, M.; Chote, P.; Fukui, A.; Collaboration: MOA Collaboration; OGLE Collaboration; muFUN Collaboration; MiNDSTEp Consortium; PLANET Collaboration; RoboNet Collaboration; and others

    2013-05-10

    Although many models have been proposed, the physical mechanisms responsible for the formation of low-mass brown dwarfs (BDs) are poorly understood. The multiplicity properties and minimum mass of the BD mass function provide critical empirical diagnostics of these mechanisms. We present the discovery via gravitational microlensing of two very low mass, very tight binary systems. These binaries have directly and precisely measured total system masses of 0.025 M{sub Sun} and 0.034 M{sub Sun }, and projected separations of 0.31 AU and 0.19 AU, making them the lowest-mass and tightest field BD binaries known. The discovery of a population of such binaries indicates that BD binaries can robustly form at least down to masses of {approx}0.02 M{sub Sun }. Future microlensing surveys will measure a mass-selected sample of BD binary systems, which can then be directly compared to similar samples of stellar binaries.

  1. MARVELS Radial Velocity Solutions to Seven Kepler Eclipsing Binaries

    NASA Astrophysics Data System (ADS)

    Heslar, Michael Francis; Thomas, Neil B.; Ge, Jian; Ma, Bo; Herczeg, Alec; Reyes, Alan; SDSS-III MARVELS Team

    2016-01-01

    Eclipsing binaries serve momentous purposes to improve the basis of understanding aspects of stellar astrophysics, such as the accurate calculation of the physical parameters of stars and the enigmatic mass-radius relationship of M and K dwarfs. We report the investigation results of 7 eclipsing binary candidates, initially identified by the Kepler mission, overlapped with the radial velocity observations from the SDSS-III Multi-Object APO Radial-Velocity Exoplanet Large-Area Survey (MARVELS). The RV extractions and spectroscopic solutions of these eclipsing binaries were generated by the University of Florida's 1D data pipeline with a median RV precision of ~60-100 m/s, which was utilized for the DR12 data release. We performed the cross-reference fitting of the MARVELS RV data and the Kepler photometric fluxes obtained from the Kepler Eclipsing Binary Catalog (V2) and modelled the 7 eclipsing binaries in the BinaryMaker3 and PHOEBE programs. This analysis accurately determined the absolute physical and orbital parameters of each binary. Most of the companion stars were determined to have masses of K and M dwarf stars (0.3-0.8 M⊙), and allowed for an investigation into the mass-radius relationship of M and K dwarfs. Among the cases are KIC 9163796, a 122.2 day period "heartbeat star", a recently-discovered class of eccentric binaries known for tidal distortions and pulsations, with a high eccentricity (e~0.75) and KIC 11244501, a 0.29 day period, contact binary with a double-lined spectrum and mass ratio (q~0.45). We also report on the possible reclassification of 2 Kepler eclipsing binary candidates as background eclipsing binaries based on the analysis of the flux measurements, flux ratios of the spectroscopic and photometric solutions, the differences in the FOVs, the image processing of Kepler, and RV and spectral analysis of MARVELS.

  2. Accretion disc mapping of the shortest period eclipsing binary SDSS J0926+36

    NASA Astrophysics Data System (ADS)

    Schlindwein, W.; Baptista, R.

    2014-10-01

    AM CVn stars are ultracompact binaries (P_{orb}< 65 min) where a hydrogen-deficient low-mass, degenerate donor star overfills its Roche lobe and transfers matter to a companion white dwarf via an accretion disc. SDSS J0926+36 is currently the only eclipsing AM CVn star and also the shortest period eclipsing binary known. Its light curve displays deep (˜ 2 mag) eclipses every 28.3 min, which last for ˜ 2 min, as well as ˜ 2 mag amplitude outbursts every ˜ 100-200 d. Superhumps were seen in its quiescent light curve in some occasions, probably as a reminiscence of a (in some cases undetected) previous outburst. Its eclipsing nature allows a unique opportunity to disentangle the emission from several different light sources, and to map the surface brightness distribution of its hydrogen-deficient accretion disc with the aid of maximum entropy eclipse mapping techniques. Here we report the eclipse mapping analysis of optical light curves of SDSS J0926+36, collected with the 2.4 m Liverpool Robotic Telescope, covering 20 orbits of the binary over 5 nights of observations between 2012 February and March. The object was in quiescence at all runs. Our data show no evidence of superhumps nor of orbital modulation due to anisotropic emission from a bright spot at disc rim. Accordingly, the average out-of-eclipse flux level is consistent with that of the superhump-subtracted previous light curves. We combined all runs to obtain an orbital light curve of improved S/N. The corresponding eclipse map shows a compact source at disc centre (T_{b}simeq 17000 K), a faint, cool accretion disc (˜ 4000 K) plus enhanced emission along the gas stream (˜ 6000 K) beyond the impact point at the outer disc rim, suggesting the occurrence of gas stream overflow at that epoch.

  3. 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.

  4. Properties OF M31. V. 298 eclipsing binaries from PAndromeda

    SciTech Connect

    Lee, C.-H.; Koppenhoefer, J.; Seitz, S.; Bender, R.; Riffeser, A.; Kodric, M.; Hopp, U.; Snigula, J.; Gössl, C.; Kudritzki, R.-P.; Burgett, W.; Chambers, K.; Hodapp, K.; Kaiser, N.; Waters, C.

    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 detached eclipsing binaries spectroscopically and determine the distance to M31.

  5. OGLE-2005-BLG-153: MICROLENSING DISCOVERY AND CHARACTERIZATION OF A VERY LOW MASS BINARY

    SciTech Connect

    Hwang, K.-H.; Han, C.; Ryu, Y.-H.; Udalski, A.; Kubiak, M.; Szymanski, M. K.; Pietrzynski, G.; Soszynski, I.; Szewczyk, O.; Ulaczyk, K.; Wyrzykowski, L.; Bond, I. A.; Beaulieu, J.-P.; Dominik, M.; Horne, K.; Gould, A.; Gaudi, B. S.; Abe, F.; Botzler, C. S.; Hearnshaw, J. B.

    2010-11-01

    The mass function and statistics of binaries provide important diagnostics of the star formation process. Despite this importance, the mass function at low masses remains poorly known due to observational difficulties caused by the faintness of the objects. Here we report the microlensing discovery and characterization of a binary lens composed of very low mass stars just above the hydrogen-burning limit. From the combined measurements of the Einstein radius and microlens parallax, we measure the masses of the binary components of 0.10 {+-} 0.01 M{sub sun} and 0.09 {+-} 0.01 M{sub sun}. This discovery demonstrates that microlensing will provide a method to measure the mass function of all Galactic populations of very low mass binaries that is independent of the biases caused by the luminosity of the population.

  6. No eclipses in the double WD binary SDSS J125733.63+542850.5

    NASA Astrophysics Data System (ADS)

    Shporer, A.; Kaplan, D.; Bildsten, L.; Howell, S.; Steinfadt, J.

    2010-08-01

    We have carried out a search with the Faulkes Telescope North (FTN) for eclipses in the binary white dwarf (WD) system SDSS J125733.63+542850.5, resulting in a non-detection. SDSS J125733.63+542850.5 was identified by Marsh et al. (2010) and Kulkarni & van Kerkwijk (2010) as a binary system consisting of a low-mass He WD (the primary) and a high-mass CO WD (the secondary), with an orbital period of 4.56 hours.

  7. STATE TRANSITIONS IN LOW-MASS X-RAY BINARIES

    SciTech Connect

    Bradley, Charles K.; Frank, Juhan

    2009-10-10

    We investigate the model of disk/coronal accretion into a black hole. We show that the inner regions of an accretion disk in X-ray binaries can transform from a cool standard disk to an advection-dominated flow through the known properties of Coulomb interaction in a two-temperature plasma, viscous heating, radiative processes, and thermal conduction. A hot, diffuse corona covering the disk is powered by accretion, but it exchanges mass with the underlying cold disk. If the accretion rate in the system is low enough, we show that the corona evaporates the disk away, leaving an advective flow to continue toward the hole. In the soft/hard transition commonly seen in X-ray binaries, we show that this advective flow can recondense back onto the underlying disk if the change in the system's accretion rate is slow enough due to thermal conduction. Unabsorbed spectra are produced to test against observations as well as prediction of the location of truncation radii of the accretion disk.

  8. Eclipsing Binaries with Classical Cepheid Component in the Magellanic System

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

    We present a census of eclipsing binary systems with classical Cepheid as a component. All such systems known were found in the OGLE collection of classical Cepheids in the Magellanic System. We extend the list of potential candidates adding four new objects found in the OGLE-IV photometric data. One of the new Cepheids in the eclipsing system, OGLE-SMC-CEP-3235, revealed only one eclipse during 15 years of the OGLE photometric monitoring. However, it additionally shows very well pronounced light-time effect indicating that the binarity is real and the system is physically bound. We also search for the light-time effect in other known eclipsing Cepheids and we clearly detect it in OGLE-LMC-CEP-1812. We discuss application of this tool for the search for Cepheids in non-eclipsing binary systems.

  9. High ionisation absorption in low mass X-ray binaries

    NASA Astrophysics Data System (ADS)

    Ponti, G.; Bianchi, S.; Muñoz-Darias, T.; De, K.; Fender, R.; Merloni, A.

    2016-05-01

    The advent of the new generation of X-ray telescopes yielded a significant step forward in our understanding of ionised absorption generated in the accretion discs of X-ray binaries. It has become evident that these relatively weak and narrow absorption features, sporadically present in the X-ray spectra of some systems, are actually the signature of equatorial outflows, which might carry away more matter than that being accreted. Therefore, they play a major role in the accretion phenomenon. These outflows (or ionised atmospheres) are ubiquitous during the softer states but absent during the power-law dominated, hard states, suggesting a strong link with the state of the inner accretion disc, presence of the radio-jet and the properties of the central source. Here, we discuss the current understanding of this field.

  10. The detached eclipsing binary TX Her revisited

    NASA Astrophysics Data System (ADS)

    Erdem, A.; Aliçavuş, F.; Soydugan, F.; Doğru, S. S.; Soydugan, E.; Çiçek, C.; Demircan, O.

    2011-12-01

    This paper presents new CCD Bessell BVRI light curves and photometric analysis of the Algol-type binary star TX Her. The CCD observations were carried out at Çanakkale Onsekiz Mart University Observatory in 2010. New BVRI light curves from this study and radial velocity curves from Popper (1970) were solved simultaneously using modern light and radial velocity curves synthesis methods. The general results show that TX Her is a well-detached eclipsing binary, however, both component stars fill at least half of their Roche lobes. A significant third light contribution to the total light of the system could not be determined. Using O- C residuals formed by the updated minima times, an orbital period study of the system was performed. It was confirmed that the tilted sinusoidal O- C variation corresponds to an apparent period variation caused by the light travel time effect due to an unseen third body. The following absolute parameters of the components were derived: M1 = 1.62 ± 0.04 M ⊙, M2 = 1.45 ± 0.03 M ⊙, R1 = 1.69 ± 0.03 R ⊙, R2 = 1.43 ± 0.03 R ⊙, L1 = 8.21 ± 0.90 L ⊙ and L2 = 3.64 ± 0.60 L ⊙. The distance to TX Her was calculated as 155 ± 10 pc, taking into account interstellar extinction. The position of the components of TX Her in the HR diagram are also discussed. The components are young stars with an age of ˜500 Myr.

  11. Eclipsing Binaries from the Kepler Mission

    NASA Technical Reports Server (NTRS)

    Koch, David; Borucki, William; Lissauer, J.; Basri, Gibor; Brown, Timothy; Caldwell, Douglas; Cochran, William; Jenkins, Jon; Dunham, Edward; Gautier, Nick

    2005-01-01

    The Kepler Mission is a photometric space mission that will continuously observe a single 100 sq deg field of view (FOV) of greater than 100,000 stars in the Cygnus-Lyra region for 4 or more years with a precision of 14 ppm (R=12). The primary goal of the mission is to detect Earth-size planets in the habitable zone of solar-like stars. In the process, many eclipsing binaries (EB) will also be detected. Prior to launch, the stellar characteristics will have been detennined for all the stars in the FOV with R<16. As part of the verification process, stars with transits <5% will need to have follow-up radial velocity observations performed to determine the component masses and thereby separate transits caused by stellar companions from those caused by planets. The result will be a rich database on EBs. The community will have access to the archive for uses such as for EB modeling of the high-precision light curves. A guest observer program is also planned for objects not already on the target list.

  12. A New Class of Nascent Eclipsing Binaries with Extreme Mass Ratios

    NASA Astrophysics Data System (ADS)

    Moe, Maxwell; Di Stefano, Rosanne

    2015-03-01

    Early B-type main-sequence (MS) stars (M 1 ≈ 5-16 M ⊙) with closely orbiting low-mass stellar companions (q = M 2/M 1 < 0.25) can evolve to produce Type Ia supernovae, low-mass X-ray binaries, and millisecond pulsars. However, the formation mechanism and intrinsic frequency of such close extreme mass-ratio binaries have been debated, especially considering none have hitherto been detected. Utilizing observations of the Large Magellanic Cloud galaxy conducted by the Optical Gravitational Lensing Experiment, we have discovered a new class of eclipsing binaries in which a luminous B-type MS star irradiates a closely orbiting low-mass pre-MS companion that has not yet fully formed. The primordial pre-MS companions have large radii and discernibly reflect much of the light they intercept from the B-type MS primaries (ΔI 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 2 ≈ 0.8-2.4 M ⊙ (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 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.

  13. Timing of eclipsing binary V0873 Per: a third body candidate

    NASA Astrophysics Data System (ADS)

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

    2016-01-01

    We analyze a set of moments of minima of eclipsing variable V0873 Per. V0873 Per is a short-period low-mass binary star. Data about moments of minima of V0873 Per were taken from the literature and our observations during 2013-2014. Our aim is to test the system on existence of new bodies using timing of minima of eclipses. We found a periodic variation of orbital period of V0873 Per. This variation can be explained by the gravitational influence of a third companion on the central binary star. The mass of the third body candidate is ≈ 0.2 M_{⊙}, and its orbital period is ≈300 days. The paper also includes a table with moments of minima calculated from our observations, which can be used in future investigations of V0873 Per.

  14. The ELM Survey. VII. Orbital Properties of Low-Mass White Dwarf Binaries

    NASA Astrophysics Data System (ADS)

    Brown, Warren R.; Gianninas, A.; Kilic, Mukremin; Kenyon, Scott J.; Allende Prieto, Carlos

    2016-02-01

    We present the discovery of 15 extremely low-mass (5\\lt {log}g\\lt 7) white dwarf (WD) candidates, 9 of which are in ultra-compact double-degenerate binaries. Our targeted extremely low-mass Survey sample now includes 76 binaries. The sample has a lognormal distribution of orbital periods with a median period of 5.4 hr. The velocity amplitudes imply that the binary companions have a normal distribution of mass with 0.76 M⊙ mean and 0.25 M⊙ dispersion. Thus extremely low-mass WDs are found in binaries with a typical mass ratio of 1:4. Statistically speaking, 95% of the WD binaries have a total mass below the Chandrasekhar mass, and thus are not type Ia supernova progenitors. Yet half of the observed binaries will merge in less than 6 Gyr due to gravitational wave radiation; probable outcomes include single massive WDs and stable mass transfer AM CVn binaries. Based on observations obtained at the MMT Observatory, a joint facility of the Smithsonian Institution and the University of Arizona.

  15. 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.

  16. PERIOD ERROR ESTIMATION FOR THE KEPLER ECLIPSING BINARY CATALOG

    SciTech Connect

    Mighell, Kenneth J.; Plavchan, Peter

    2013-06-15

    The Kepler Eclipsing Binary Catalog (KEBC) describes 2165 eclipsing binaries identified in the 115 deg{sup 2} Kepler Field based on observations from Kepler quarters Q0, Q1, and Q2. The periods in the KEBC are given in units of days out to six decimal places but no period errors are provided. We present the PEC (Period Error Calculator) algorithm, which can be used to estimate the period errors of strictly periodic variables observed by the Kepler Mission. The PEC algorithm is based on propagation of error theory and assumes that observation of every light curve peak/minimum in a long time-series observation can be unambiguously identified. The PEC algorithm can be efficiently programmed using just a few lines of C computer language code. The PEC algorithm was used to develop a simple model that provides period error estimates for eclipsing binaries in the KEBC with periods less than 62.5 days: log {sigma}{sub P} Almost-Equal-To - 5.8908 + 1.4425(1 + log P), where P is the period of an eclipsing binary in the KEBC in units of days. KEBC systems with periods {>=}62.5 days have KEBC period errors of {approx}0.0144 days. Periods and period errors of seven eclipsing binary systems in the KEBC were measured using the NASA Exoplanet Archive Periodogram Service and compared to period errors estimated using the PEC algorithm.

  17. A DEEPLY ECLIPSING DETACHED DOUBLE HELIUM WHITE DWARF BINARY

    SciTech Connect

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

    2011-07-10

    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} = 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.

  18. Period Error Estimation for the Kepler Eclipsing Binary Catalog

    NASA Astrophysics Data System (ADS)

    Mighell, Kenneth J.; Plavchan, Peter

    2013-06-01

    The Kepler Eclipsing Binary Catalog (KEBC) describes 2165 eclipsing binaries identified in the 115 deg2 Kepler Field based on observations from Kepler quarters Q0, Q1, and Q2. The periods in the KEBC are given in units of days out to six decimal places but no period errors are provided. We present the PEC (Period Error Calculator) algorithm, which can be used to estimate the period errors of strictly periodic variables observed by the Kepler Mission. The PEC algorithm is based on propagation of error theory and assumes that observation of every light curve peak/minimum in a long time-series observation can be unambiguously identified. The PEC algorithm can be efficiently programmed using just a few lines of C computer language code. The PEC algorithm was used to develop a simple model that provides period error estimates for eclipsing binaries in the KEBC with periods less than 62.5 days: log σ P ≈ - 5.8908 + 1.4425(1 + log P), where P is the period of an eclipsing binary in the KEBC in units of days. KEBC systems with periods >=62.5 days have KEBC period errors of ~0.0144 days. Periods and period errors of seven eclipsing binary systems in the KEBC were measured using the NASA Exoplanet Archive Periodogram Service and compared to period errors estimated using the PEC algorithm.

  19. A LONG-PERIOD TOTALLY ECLIPSING BINARY STAR AT THE TURNOFF OF THE OPEN CLUSTER NGC 6819 DISCOVERED WITH KEPLER

    SciTech Connect

    Sandquist, Eric L.; Orosz, Jerome A.; Jeffries, Mark W. Jr.; Brewer, Lauren N. E-mail: orosz@sciences.sdsu.edu; and others

    2013-01-01

    We present the discovery of the totally eclipsing long-period (P = 771.8 days) binary system WOCS 23009 in the old open cluster NGC 6819 that contains both an evolved star near central hydrogen exhaustion and a low-mass (0.45 M {sub Sun }) star. This system was previously known to be a single-lined spectroscopic binary, but the discovery of an eclipse near apastron using data from the Kepler space telescope makes it clear that the system has an inclination that is very close to 90 Degree-Sign . Although the secondary star has not been identified in spectra, the mass of the primary star can be constrained using other eclipsing binaries in the cluster. The combination of the total eclipses and a mass constraint for the primary star allows us to determine a reliable mass for the secondary star and radii for both stars, and to constrain the cluster age. Unlike well-measured stars of similar mass in field binaries, the low-mass secondary is not significantly inflated in radius compared to model predictions. The primary star characteristics, in combination with cluster photometry and masses from other cluster binaries, indicate a best age of 2.62 {+-} 0.25 Gyr, although stellar model physics may introduce systematic uncertainties at the {approx}10% level. We find preliminary evidence that the asteroseismic predictions for red giant masses in this cluster are systematically too high by as much as 8%.

  20. Eclipsing binaries in the Gaia era: automated detection performance

    NASA Astrophysics Data System (ADS)

    Holl, Berry; Mowlavi, Nami; Lecoeur-Taïbi, Isabelle; Geneva Gaia CU7 Team members

    2014-09-01

    Binary systems can have periods from a fraction of a day to several years and exist in a large range of possible configurations at various evolutionary stages. About 2% of them are oriented such that eclipses can be observed. Such observations provide unique opportunities for the determination of their orbital and stellar parameters. Large-scale multi-epoch photometric surveys produce large sets of eclipsing binaries that allow for statistical studies of binary systems. In this respect the ESA Gaia mission, launched in December 2013, is expected to deliver an unprecedented sample of millions of eclipsing binaries. Their detection from Gaia photometry and estimation of their orbital periods are essential for their subclassification and orbital and stellar parameter determination. For a subset of these eclipsing systems, Gaia radial velocities and astrometric orbital measurements will further complement the Gaia light curves. A key challenge of the detection and period determination of the expected millions of Gaia eclipsing binaries is the automation of the procedure. Such an automated pipeline is being developed within the Gaia Data Processing Analysis Consortium, in the framework of automated detection and identification of various types of photometric variable objects. In this poster we discuss the performance of this pipeline on eclipsing binaries using simulated Gaia data and the existing Hipparcos data. We show that we can detect a wide range of binary systems and very often determine their orbital periods from photometry alone, even though the data sampling is relatively sparse. The results can further be improved for those objects for which spectroscopic and/or astrometric orbital measurements will also be available from Gaia.

  1. Relativistic Astrophysics in Black Hole and Low-Mass Neutron Star X-ray Binaries

    NASA Technical Reports Server (NTRS)

    2000-01-01

    During the five-year period, our study of "Relativistic Astrophysics in Black Hole and Low-Mass Neutron Star X-ray Binaries" has been focused on the following aspects: observations, data analysis, Monte-Carlo simulations, numerical calculations, and theoretical modeling. Most of the results of our study have been published in refereed journals and conference presentations.

  2. 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. PMID:21107425

  3. Towards a fully automated eclipsing binary solver for Gaia

    NASA Astrophysics Data System (ADS)

    Tingley, Brandon; Sadowski, Gilles; Siopis, Christos

    2009-02-01

    Gaia, an ESA cornerstone mission, will obtain of the order of 100 high-precision photometric observations and lower precision radial velocity measurements over five years for around a billion stars several hundred thousand of which will be eclipsing binaries. In order to extract the characteristics of these systems, a fully automated code must be available. During the process of this development, two tools that may be of use to the transit community have emerged: a very fast, simple, detached eclipsing binary simulator/solver based on a new approach and an interacting eclipsing binary simulator with most of the features of the Wilson-Devinney and Nightfall codes, but fully documented and written in easy-to-follow and highly portable Java. Currently undergoing development and testing, this code includes an intuitive graphical interface and an optimizer for the estimation of the physical parameters of the system.

  4. A search for eclipses of HD 114762 by a low-mass companion

    SciTech Connect

    Robinson, E.L.; Cochran, A.L.; Cochran, W.D.; Shafter, A.W.; Zhang, Erho Beijing Observatory )

    1990-02-01

    HD 114762 has an unseen companion with a dynamical mass that satisfies the constraint mass sin i = 2.5 x 10 to the 31st gm. The companion is a good candidate for a planetary-mass object, but the inclination of its orbit is unknown and its mass is indeterminate. Tests were conducted for the specific case of a nearly edge-on orbit by looking for eclipses of HD 114762 by the companion. Although the a priori probability of an eclipse is low, this is a crucial case because the companion has its minimum mass if the orbit is edge on. No eclipses were found with a depth greater than 0.01 mag and, therefore, the inclination of the orbit of HD 114762 is less than 89 deg. 12 refs.

  5. Discovery of Triple Star Systems through Dynamical Eclipse Timing Variations with Kepler Eclipsing Binaries

    NASA Astrophysics Data System (ADS)

    Conroy, Kyle E.

    2016-05-01

    We present a catalog of precise eclipse times and analysis of third-body signals among 1279 close binaries in the latest Kepler Eclipsing Binary Catalog. For these short-period binaries, Kepler's 30 minute exposure time causes significant smearing of light curves. In addition, common astrophysical phenomena such as chromospheric activity, as well as imperfections in the light curve detrending process, can create systematic artifacts that may produce fictitious signals in the eclipse timings. We present a method to measure precise eclipse times in the presence of distorted light curves, such as in contact and near-contact binaries which exhibit continuously changing light levels in and out of eclipse. We identify 236 systems for which we find a timing variation signal compatible with the presence of a third body. These are modeled for the light travel time effect and the basic properties of the third body are derived. We summarize the overall distribution of mutual orbital inclination angles, which together now provide strong confirmation of the basic predictions of dynamical evolution through Kozai Cycles and Tidal Friction.

  6. Spectroscopy of Low Mass X-Ray Binaries: New Insights into Accretion

    NASA Technical Reports Server (NTRS)

    DilVrtilek, Saeqa; Mushotsky, Richard (Technical Monitor)

    2004-01-01

    This project is to observe two low mass X-ray binaries, chosen for their X-ray brightness, low column density, and diversity of accretion behavior. The high spectral resolution of the RGS, the broad energy range and tremendous collecting power of EPIC, and simultaneous optical monitoring with the OM are particularly well-suited to these studies. The second of two objects was observed on September of 2002. Data analysis for both observation has been completed: an investigation of the physical conditions of the emitting gas using emission and recombination line diagnostics to determine temperatures, densities, elemental abundances, and ionization structure. A study of behavior of the emission features as a function of binary orbit shows modulated behavior in one of the systems. A paper on "High-resolution observations of low-mass X-ray binaries" is near completion. The paper includes observations with the Chandra HETG that are not yet completed.

  7. 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/.

  8. ON THE DISTRIBUTION OF ORBITAL ECCENTRICITIES FOR VERY LOW-MASS BINARIES

    SciTech Connect

    Dupuy, Trent J.; Liu, Michael C.

    2011-06-01

    We have compiled a sample of 16 orbits for very low-mass stellar (<0.1 M{sub sun}) and brown dwarf binaries, including updated orbits for HD 130948BC and LP 415-20AB. This sample enables the first comprehensive study of the eccentricity distribution for such objects. We find that very low-mass binaries span a broad range of eccentricities from near-circular to highly eccentric (e {approx} 0.8), with a median eccentricity of 0.34. We have examined potential observational biases in this sample, and for visual binaries we show through Monte Carlo simulations that if we choose appropriate selection criteria then all eccentricities are equally represented ({approx}< 5% difference between input and output eccentricity distributions). The orbits of this sample of very low-mass binaries show some significant differences from their solar-type counterparts. They lack a correlation between orbital period and eccentricity, and display a much higher fraction of near-circular orbits (e < 0.1) than solar-type stars, which together may suggest a different formation mechanism or dynamical history for these two populations. Very low-mass binaries also do not follow the e{sup 2} distribution of Ambartsumian, which would be expected if their orbits were distributed in phase space according to a function of energy alone (e.g., the Boltzmann distribution). We find that current numerical simulations of very low-mass star formation do not completely reproduce the observed properties of our binary sample. The cluster formation model of Bate agrees very well with the overall e distribution, but the lack of any high-e (>0.6) binaries at orbital periods comparable to our sample suggests that tidal damping due to gas disks may play too large of a role in the simulations. In contrast, the circumstellar disk fragmentation model of Stamatellos and Whitworth predicts only high-e binaries and thus is highly inconsistent with our sample. These discrepancies could be explained if multiple formation

  9. On the formation of galactic black hole low-mass X-ray binaries

    NASA Astrophysics Data System (ADS)

    Wang, Chen; Jia, Kun; Li, Xiang-Dong

    2016-03-01

    Currently, there are 24 black hole (BH) X-ray binary systems that have been dynamically confirmed in the Galaxy. Most of them are low-mass X-ray binaries (LMXBs) comprised of a stellar-mass BH and a low-mass donor star. Although the formation of these systems has been extensively investigated, some crucial issues remain unresolved. The most noticeable one is that, the low-mass companion has difficulties in ejecting the tightly bound envelope of the massive primary during the spiral-in process. While initially intermediate-mass binaries are more likely to survive the common envelope (CE) evolution, the resultant BH LMXBs mismatch the observations. In this paper, we use both stellar evolution and binary population synthesis to study the evolutionary history of BH LMXBs. We test various assumptions and prescriptions for the supernova mechanisms that produce BHs, the binding energy parameter, the CE efficiency and the initial mass distributions of the companion stars. We obtain the birthrate and the distributions of the donor mass, effective temperature and orbital period for the BH LMXBs in each case. By comparing the calculated results with the observations, we put useful constraints on the aforementioned parameters. In particular, we show that it is possible to form BH LMXBs with the standard CE scenario if most BHs are born through failed supernovae.

  10. Photometric Analysis and Period Investigation of the EW Type Eclipsing Binary V441 Lac

    NASA Astrophysics Data System (ADS)

    Li, K.; Hu, S.-M.; Guo, D.-F.; Jiang, Y.-G.; Gao, D.-Y.; Chen, X.

    2016-09-01

    Four color light curves of the EW type eclipsing binary V441 Lac were presented and analyzed by the W-D code. It is found that V441 Lac is an extremely low mass ratio ( q = 0.093±0.001) semi-detached binary with the less massive secondary component filling the inner Roche lobe. Two dark spots on the primary component were introduced to explain the asymmetric light curves. By analyzing all times of light minimum, we determined that the orbital period of V441 Lac is continuously increasing at a rate of d P/d t = 5.874(±0.007) × 10-7 d yr-1. The semi-detached Algol type configuration of V441 Lac is possibly formed by a contact configuration destroyed shallow contact binary due to mass transfer from the less massive component to the more massive one predicted by the thermal relaxation oscillation theory.

  11. Photometric Study on an Eclipsing Close Binary System NSVS 14256825

    NASA Astrophysics Data System (ADS)

    Yilmaz, Semra; Kalomeni, Belinda

    2016-07-01

    Photometric Study on an Eclipsing Close Binary System NSVS 14256825 We present multi colour light variations of a close binary system NSVS14256825 obtained at the TÜBİTAK National Observatory with T100 telescope. Orbital and physical parameters of the system NSVS14256825 are obtained by simultaneous solution of the newly obtained data with the photometric and spectroscopic data that exist in the literature .

  12. Photoelectric Photometry of the Eclipsing Binary V505-MONOCEROTIS

    NASA Astrophysics Data System (ADS)

    Chochol, D.; Bakos, G. A.; Bartolini, C.; Guarnieri, A.; Dapergolas, A.; Szabados, L.

    Photoelectric U, B, V observations of the eclipsing binary V 505 Mon, performed at the observatories in Skalnate Pleso, Budapest, Bologna and Waterloo in the years 1972-1984 are presented. The following ephemeris has been derived, using all these data: prim.min. Indications of ongoing mass transfer in a semidetached binary configuration are presented. The possible causes of the observed short-term changes of brightness are discussed.

  13. Discovery of the Eclipsing Detached Double White Dwarf Binary NLTT 11748

    NASA Astrophysics Data System (ADS)

    Steinfadt, Justin D. R.; Kaplan, D. L.; Shporer, A.; Bildsten, L.; Howell, S. B.

    2011-01-01

    We report the discovery of the first eclipsing detached double white dwarf (WD) binary, NLTT 11748. In a photometric search for pulsations from this low-mass helium core WD, we discovered approx 180 s 3%--6% dips in the photometry. Subsequent radial velocity measurements found variations with a semi-amplitude K1 = 271 ± 3 km/s (also now reported by Kawka et al. and Kilic et al.) and confirmed the dips as eclipses caused by an orbiting WD with a mass M2 = 0.648--0.771 Msun for M1 = 0.1--0.2 Msun. We detect both the primary and secondary eclipses during the Porb = 5.64 hr orbit and measure the secondary's brightness to be 3.5% ± 0.3% of the primary at SDSS-g'. Assuming that the secondary follows the mass-radius relation of a cold C/O WD and including the effects of microlensing in the binary, the primary eclipse yields a primary radius of R1 = 0.043--0.039 Rsun for M1 = 0.1--0.2 Msun, consistent with the theoretically expected values for a helium core WD with a thick, stably burning hydrogen envelope. I will discuss how our future observational efforts, such as detection of the secondary semi-amplitude K2, multiband high-cadence photometric eclipse observations, and cross system time-delay measurements, will determine M1, yielding accurate WD mass-radius measurement of both components, as well as a clearer indication of the binary's fate once contact is reached.

  14. 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.

  15. 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

  16. Kepler Eclipsing Binary Stars. VII. The Catalog of Eclipsing Binaries Found in the Entire Kepler Data Set

    NASA Astrophysics Data System (ADS)

    Kirk, Brian; Conroy, Kyle; Prša, Andrej; Abdul-Masih, Michael; Kochoska, Angela; Matijevič, Gal; Hambleton, Kelly; Barclay, Thomas; Bloemen, Steven; Boyajian, Tabetha; Doyle, Laurance R.; Fulton, B. J.; Hoekstra, Abe Johannes; Jek, Kian; Kane, Stephen R.; Kostov, Veselin; Latham, David; Mazeh, Tsevi; Orosz, Jerome A.; Pepper, Joshua; Quarles, Billy; Ragozzine, Darin; Shporer, Avi; Southworth, John; Stassun, Keivan; Thompson, Susan E.; Welsh, William F.; Agol, Eric; Derekas, Aliz; Devor, Jonathan; Fischer, Debra; Green, Gregory; Gropp, Jeff; Jacobs, Tom; Johnston, Cole; LaCourse, Daryll Matthew; Saetre, Kristian; Schwengeler, Hans; Toczyski, Jacek; Werner, Griffin; Garrett, Matthew; Gore, Joanna; Martinez, Arturo O.; Spitzer, Isaac; Stevick, Justin; Thomadis, Pantelis C.; Vrijmoet, Eliot Halley; Yenawine, Mitchell; Batalha, Natalie; Borucki, William

    2016-03-01

    The primary Kepler Mission provided nearly continuous monitoring of ∼200,000 objects with unprecedented photometric precision. We present the final catalog of eclipsing binary systems within the 105 deg2 Kepler field of view. This release incorporates the full extent of the data from the primary mission (Q0-Q17 Data Release). As a result, new systems have been added, additional false positives have been removed, ephemerides and principal parameters have been recomputed, classifications have been revised to rely on analytical models, and eclipse timing variations have been computed for each system. We identify several classes of systems including those that exhibit tertiary eclipse events, systems that show clear evidence of additional bodies, heartbeat systems, systems with changing eclipse depths, and systems exhibiting only one eclipse event over the duration of the mission. We have updated the period and galactic latitude distribution diagrams and included a catalog completeness evaluation. The total number of identified eclipsing and ellipsoidal binary systems in the Kepler field of view has increased to 2878, 1.3% of all observed Kepler targets. An online version of this catalog with downloadable content and visualization tools is maintained at http://keplerEBs.villanova.edu.

  17. The Turbulent Fragmentation Origin of Low-Mass Binary Star Systems

    NASA Astrophysics Data System (ADS)

    Offner, Stella; Kratter, K. M.; Matzner, C. D.; Krumholz, M. R.; Klein, R. I.

    2011-01-01

    Using self-gravitating, radiation-hydrodynamic simulations, we compare turbulent fragmentation and disk fragmentation as avenues for forming low-mass binary systems. We employ two dimensionless parameters to characterize the infall rate onto protostellar systems, describe disks' susceptability to fragmentation, and place limits on protostellar system multiplicity. While protostellar disks are predominatly stable in the presence of radiative feedback, purely hydrodynamic systems exhibit fundamentally different parameters and are strongly susceptible to disk fragmentation. Consequently, we find that turbulent fragmentation, occuring on thousand AU scales, is the more common mode of fragmentation and is likely responsible for producing most low-mass binary systems. Although fragmentation in young embedded protostellar disks cannot be directly imaged, turbulent fragmentation on these scales is potentially observable.

  18. Accretion disc atmospheres and winds in low-mass X-ray binaries

    NASA Astrophysics Data System (ADS)

    Díaz Trigo, M.; Boirin, L.

    2016-05-01

    In the last decade, X-ray spectroscopy has enabled a wealth of discoveries of photoionised absorbers in X-ray binaries. Studies of such accretion disc atmospheres and winds are of fundamental importance to understand accretion processes and possible feedback mechanisms to the environment. In this work, we review the current observational state and theoretical understanding of accretion disc atmospheres and winds in low-mass X-ray binaries, focusing on the wind launching mechanisms and on the dependence on accretion state. We conclude with issues that deserve particular attention.

  19. 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.

  20. Eclipsing Binary Science through the Monocle of Kepler

    NASA Astrophysics Data System (ADS)

    Prsa, Andrej; Eclipsing Binary Working Group

    2013-07-01

    The notable success of space-borne missions such as MOST, CoRoT and Kepler triggered a surge of exciting new results in stellar astrophysics, ranging from asteroseismology, discoveries of new subclasses of objects such as heartbeat stars, to the literal firehose of extrasolar planets. The nearly continuous observing mode and an unprecedented photometric precision provide us with data that challenge even the most sophisticated models. Eclipsing binary stars play a major role since their accurate modeling provides fundamental stellar parameters (masses, radii, temperatures and luminosities) across the H-R diagram by relying on the uniquely favorable geometry that alleviates the need for any calibrations. NASA's Kepler mission is particularly well suited for the study of binaries; the ~10-ppm precision and the ~105-square degree field of view yield a sample of ~2500 eclipsing systems of varying types and morphologies, that have been observed uninterruptedly for 4 years in a row. I will present statistical results of the complete set of Kepler eclipsing binaries, including the distributions of the periods, galactic latitudes, morphologies, orbital properties and fundamental stellar parameters. The mission provided us with ground-breaking observations of multiple components through the measurements of eclipse timing variations. I will emphasize the pioneering efforts to detect and analyze stellar and substellar tertiaries orbiting binary stars and explore the implications of multiplicity on the evolution of these systems. Several theoretical aspects of reliable modeling still elude our grasp, and I will provide a theorist's perspective of the direction that our field might take in the next several years. Lastly, I will focus on a few notable "head-scratchers", systems that deserve special attention because of their uniqueness and/or general importance to astrophysics. This presentation will encapsulate the results based on the work and dedication of the entire Kepler

  1. The highly eccentric detached eclipsing binaries in ACVS and MACC

    NASA Astrophysics Data System (ADS)

    Shivvers, Isaac; Bloom, Joshua S.; Richards, Joseph W.

    2014-06-01

    Next-generation synoptic photometric surveys will yield unprecedented (for the astronomical community) volumes of data and the processes of discovery and rare-object identification are, by necessity, becoming more autonomous. Such autonomous searches can be used to find objects of interest applicable to a wide range of outstanding problems in astronomy, and in this paper we present the methods and results of a largely autonomous search for highly eccentric detached eclipsing binary systems in the Machine-learned All-Sky Automated Survey Classification Catalog. 106 detached eclipsing binaries with eccentricities of e ≳ 0.1 are presented, most of which are identified here for the first time. We also present new radial-velocity curves and absolute parameters for six of those systems with the long-term goal of increasing the number of highly eccentric systems with orbital solutions, thereby facilitating further studies of the tidal circularization process in binary stars.

  2. Photometric study of the pulsating, eclipsing binary OO DRA

    SciTech Connect

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

    2014-12-01

    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.

  3. Kepler Eclipsing Binary Stars. III. Classification of Kepler Eclipsing Binary Light Curves with Locally Linear Embedding

    NASA Astrophysics Data System (ADS)

    Matijevič, Gal; Prša, Andrej; Orosz, Jerome A.; Welsh, William F.; Bloemen, Steven; Barclay, Thomas

    2012-05-01

    We present an automated classification of 2165 Kepler eclipsing binary (EB) light curves that accompanied the second Kepler data release. The light curves are classified using locally linear embedding, a general nonlinear dimensionality reduction tool, into morphology types (detached, semi-detached, overcontact, ellipsoidal). The method, related to a more widely used principal component analysis, produces a lower-dimensional representation of the input data while preserving local geometry and, consequently, the similarity between neighboring data points. We use this property to reduce the dimensionality in a series of steps to a one-dimensional manifold and classify light curves with a single parameter that is a measure of "detachedness" of the system. This fully automated classification correlates well with the manual determination of morphology from the data release, and also efficiently highlights any misclassified objects. Once a lower-dimensional projection space is defined, the classification of additional light curves runs in a negligible time and the method can therefore be used as a fully automated classifier in pipeline structures. The classifier forms a tier of the Kepler EB pipeline that pre-processes light curves for the artificial intelligence based parameter estimator.

  4. KEPLER ECLIPSING BINARY STARS. III. CLASSIFICATION OF KEPLER ECLIPSING BINARY LIGHT CURVES WITH LOCALLY LINEAR EMBEDDING

    SciTech Connect

    Matijevic, Gal; Prsa, Andrej; Orosz, Jerome A.; Welsh, William F.; Bloemen, Steven; Barclay, Thomas E-mail: andrej.prsa@villanova.edu

    2012-05-15

    We present an automated classification of 2165 Kepler eclipsing binary (EB) light curves that accompanied the second Kepler data release. The light curves are classified using locally linear embedding, a general nonlinear dimensionality reduction tool, into morphology types (detached, semi-detached, overcontact, ellipsoidal). The method, related to a more widely used principal component analysis, produces a lower-dimensional representation of the input data while preserving local geometry and, consequently, the similarity between neighboring data points. We use this property to reduce the dimensionality in a series of steps to a one-dimensional manifold and classify light curves with a single parameter that is a measure of 'detachedness' of the system. This fully automated classification correlates well with the manual determination of morphology from the data release, and also efficiently highlights any misclassified objects. Once a lower-dimensional projection space is defined, the classification of additional light curves runs in a negligible time and the method can therefore be used as a fully automated classifier in pipeline structures. The classifier forms a tier of the Kepler EB pipeline that pre-processes light curves for the artificial intelligence based parameter estimator.

  5. The first light curve analysis of eclipsing binary NR Cam

    NASA Astrophysics Data System (ADS)

    Tavakkoli, F.; Hasanzadeh, A.; Poro, A.

    2015-05-01

    New observations of the eclipsing binary system NR Cam were carried out using a CCD in B, V, and R filters and new times of light minimum and new ephemeris were obtained. The B, V, and R light curves were analyzed using both the Binary Maker 3.0 and PHOEBE 0.31 programs to determine some geometrical and physical parameters of the system. These results show that NR Cam is an overcontact binary and that both components are Main Sequence stars. The O'Connell effect on NR Cam was studied and some variations in spot parameters were obtained over the different years.

  6. 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}ȯ ) 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}ȯ . 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.

  7. 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.

  8. Formation of millisecond pulsars with low-mass helium white dwarf companions in very compact binaries

    SciTech Connect

    Jia, Kun; Li, X.-D.

    2014-08-20

    Binary millisecond pulsars (BMSPs) are thought to have evolved from low-mass X-ray binaries (LMXBs). If the mass transfer in LMXBs is driven by nuclear evolution of the donor star, the final orbital period is predicted to be well correlated with the mass of the white dwarf (WD), which is the degenerate He core of the donor. Here we show that this relation can be extended to very small WD mass (∼0.14-0.17 M {sub ☉}) and narrow orbital period (about a few hours), depending mainly on the metallicities of the donor stars. There is also discontinuity in the relation, which is due to the temporary contraction of the donor when the H-burning shell crosses the hydrogen discontinuity. BMSPs with low-mass He WD companions in very compact binaries can be accounted for if the progenitor binary experienced very late Case A mass transfer. The WD companion of PSR J1738+0333 is likely to evolve from a Pop II star. For PSR J0348+0432, to explain its extreme compact orbit in the Roche-lobe-decoupling phase, even lower metallicity (Z = 0.0001) is required.

  9. 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.

  10. The Formation of Low-mass Binary Star Systems Via Turbulent Fragmentation

    NASA Astrophysics Data System (ADS)

    Offner, Stella S. R.; Kratter, Kaitlin M.; Matzner, Christopher D.; Krumholz, Mark R.; Klein, Richard I.

    2010-12-01

    We characterize the infall rate onto protostellar systems forming in self-gravitating radiation-hydrodynamics simulations. Using two dimensionless parameters to determine the disks' susceptibility to gravitational fragmentation, we infer limits on protostellar system multiplicity and the mechanism of binary formation. We show that these parameters give robust predictions even in the case of marginally resolved protostellar disks. We find that protostellar systems with radiation feedback predominately form binaries via turbulent fragmentation, not disk instability, and predict that turbulent fragmentation is the dominant channel for binary formation for low-mass stars. We clearly demonstrate that systems forming in simulations including radiative feedback have fundamentally different parameters than those in purely hydrodynamics simulations.

  11. NIP of Stars: early results and new eclipsing binaries

    NASA Astrophysics Data System (ADS)

    Jaque Arancibia, M.; Barba, R.; Morrell, N.; Roman Lopes, A.; Torres Robledo, S.; Gunthardt, G.; Soto, M.; Ferrero, G.; Arias, J. I.; Gamen, R.; Fernadez Lajus, E.

    2014-10-01

    We have performed a near-infrared photometric monitoring of 39 galactic young star clusters and star-forming regions, known as NIP of Stars, between the years 2009-2011, using the Swope telescope at Las Campanas Observatory (Chile) and the RetroCam camera, in H- and Y-bands. This monitoring program is complementary to the Vista Variables in the Via Láctea (VVV), as the brightest sources observed in NIP of Stars are saturated in VVV. The aim of this campaign is to perform a census of photometric variability of such clusters and star-forming regions, with the main goal of discovering massive eclipsing binary stars. In this work, we present a preliminary analysis of this photometric monitoring program with the discovery of tens of candidates for variable stars, among them candidates for massive eclipsing binaries. We included also to the analysis of variability, a small set of images obtained in the Ks with the VISTA telescope in the framework of VVV survey (Minniti et al. 2010). In special, we announce the infrared discovering of four massive eclipsing binaries in the massive young cluster NGC 3603. The stars have been classified spectroscopically as O-type stars, and one of them, MTT 58, has a rare star with a spectral type of O2 If*/WN6, as one of its components. We present a preliminary analysis of the light-curves of these binaries.

  12. A catalogue of temperatures for Kepler eclipsing binary stars

    NASA Astrophysics Data System (ADS)

    Armstrong, D. J.; Gómez Maqueo Chew, Y.; Faedi, F.; Pollacco, D.

    2014-02-01

    We have combined the Kepler Eclipsing Binary Catalogue with information from the HES, KIS and 2MASS photometric surveys to produce spectral energy distribution fits to over 2600 eclipsing binaries in the catalogue over a wavelength range of 0.36-2.16 Å. We present primary (T1) and secondary (T2) stellar temperatures, plus information on the stellar radii and system distance ratios. The derived temperatures are on average accurate to 370 K in T1 and 620 K in T2. Our results improve on the similarly derived physical parameters of the Kepler Input Catalogue through consideration of both stars of the binary system rather than a single star model, and inclusion of additional U-band photometry. We expect these results to aid future uses of the Kepler eclipsing binary data, both in target selection and to inform users of the extremely high-precision light curves available. We do not include surface gravities or system metallicities, as these were found to have an insignificant effect on the observed photometric bands.

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

    SciTech Connect

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

    2011-08-15

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

  14. DISCOVERY OF THE ECLIPSING DETACHED DOUBLE WHITE DWARF BINARY NLTT 11748

    SciTech Connect

    Steinfadt, Justin D. R.; Shporer, Avi; Bildsten, Lars; Kaplan, David L.; Howell, Steve B.

    2010-06-20

    We report the discovery of the first eclipsing detached double white dwarf (WD) binary. In a pulsation search, the low-mass helium core WD NLTT 11748 was targeted for fast ({approx}1 minute) differential photometry with the Las Cumbres Observatory's Faulkes Telescope North. Rather than pulsations, we discovered {approx}180 s 3%-6% dips in the photometry. Subsequent radial velocity measurements of the primary white dwarf from the Keck telescope found variations with a semi-amplitude K{sub 1} = 271 {+-} 3 km s{sup -1} and confirmed the dips as eclipses caused by an orbiting WD with a mass M{sub 2} = 0.648-0.771 M{sub sun} for M{sub 1} = 0.1-0.2 M{sub sun}. We detect both the primary and secondary eclipses during the P{sub orb} = 5.64 hr orbit and measure the secondary's brightness to be 3.5% {+-} 0.3% of the primary at SDSS-g'. Assuming that the secondary follows the mass-radius relation of a cold C/O WD and including the effects of microlensing in the binary, the primary eclipse yields a primary radius of R{sub 1} = 0.043-0.039 R{sub sun} for M{sub 1} = 0.1-0.2 M{sub sun}, consistent with the theoretically expected values for a helium core WD with a thick, stably burning hydrogen envelope. Though nearby (at {approx}150 pc), the gravitational wave strain from NLTT 11748 is likely not adequate for direct detection by the Laser Interferometer Space Antenna. Future observational efforts will determine M{sub 1}, yielding accurate WD mass-radius measurement of both components, as well as a clearer indication of the binary's fate once contact is reached.

  15. 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.

  16. Southern Very Low Mass Stars and Brown Dwarfs in Wide Binary and Multiple Systems

    NASA Astrophysics Data System (ADS)

    Caballero, José Antonio

    2007-09-01

    The results of the Königstuhl survey in the Southern Hemisphere are presented. I have searched for common proper motion companions to 173 field very low mass stars and brown dwarfs with spectral types >M5.0 V and magnitudes J<~14.5 mag. I have measured for the first time the common proper motion of two new wide systems containing very low mass components, Königstuhl 2 AB and 3 A-BC. Together with Königstuhl 1 AB and 2M 0126-50 AB, they are among the widest systems in their respective classes (r=450-11,900 AU). I have determined the minimum frequency of field wide multiples (r>100 AU) with late-type components at 5.0%+/-1.8% and the frequency of field wide late-type binaries with mass ratios q>0.5 at 1.2%+/-0.9%. These values represent a key diagnostic of evolution history and low-mass star and brown dwarf formation scenarios. In addition, the proper motions of 62 field very low mass dwarfs are measured here for the first time.

  17. Orbital Circularization of Hot and Cool Kepler Eclipsing Binaries

    NASA Astrophysics Data System (ADS)

    Van Eylen, Vincent; Winn, Joshua N.; Albrecht, Simon

    2016-06-01

    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 the 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.

  18. Period change investigation of the low mass ratio contact binary BO Ari

    NASA Astrophysics Data System (ADS)

    Kriwattanawong, W.; Tasuya, O.; Poojon, P.

    2016-04-01

    A photometric study and period change analysis for the A-type low mass ratio contact binary BO Ari is presented. The BVR light curves were fitted by using the Wilson-Devinney method. The photometric solution yields a low mass ratio of q = 0.1754(±0.0016) with a contact degree of f = 27.72%(±2.37%). We found a long-term orbital period decrease at a rate of dPdt = - 3.49 ×10-7 d yr-1. This result indicates that the system is undergoing mass transfer from the primary component to the secondary with a mass transfer rate of m˙1m1 = - 7.77 ×10-8 yr-1. With the period decrease, the inner and outer critical Roche surfaces will tighten and cause the degree of contact to increase. Therefore, BO Ari may evolve into a deeper contact system.

  19. Orbital period variations in eclipsing post-common-envelope binaries

    NASA Astrophysics Data System (ADS)

    Parsons, S. G.; Marsh, T. R.; Copperwheat, C. M.; Dhillon, V. S.; Littlefair, S. P.; Hickman, R. D. G.; Maxted, P. F. L.; Gänsicke, B. T.; Unda-Sanzana, E.; Colque, J. P.; Barraza, N.; Sánchez, N.; Monard, L. A. G.

    2010-10-01

    We present high-speed ULTRACAM photometry of the eclipsing post-common-envelope binaries DE CVn, GK Vir, NN Ser, QS Vir, RR Cae, RX J2130.6+4710, SDSS 0110+1326 and SDSS 0303+0054 and use these data to measure precise mid-eclipse times in order to detect any period variations. We detect a large (~250 s) departure from linearity in the eclipse times of QS Vir which Applegate's mechanism fails to reproduce by an order of magnitude. The only mechanism able to drive this period change is a third body in a highly elliptical orbit. However, the planetary/sub-stellar companion previously suggested to exist in this system is ruled out by our data. Our eclipse times show that the period decrease detected in NN Ser is continuing, with magnetic braking or a third body the only mechanisms able to explain this change. The planetary/sub-stellar companion previously suggested to exist in NN Ser is also ruled out by our data. Our precise eclipse times also lead to improved ephemerides for DE CVn and GK Vir. The width of a primary eclipse is directly related to the size of the secondary star and variations in the size of this star could be an indication of Applegate's mechanism or Wilson (starspot) depressions which can cause jitter in the O-C curves. We measure the width of primary eclipses for the systems NN Ser and GK Vir over several years but find no definitive variations in the radii of the secondary stars. However, our data are precise enough (Δ Rsec/Rsec < 10-5) to show the effects of Applegate's mechanism in the future. We find no evidence of Wilson depressions in either system. We also find tentative indications that flaring rates of the secondary stars depend on their mass rather than rotation rates.

  20. What is causing the eclipse in the millisecond binary pulsar

    SciTech Connect

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

    1989-07-01

    Possible physical mechanisms for explaining the radio eclipses in the millisecond binary pulsar PSR 1957 + 20 are discussed. If, as recent observations suggest, the duration of the eclipses depends on the observing frequency, a plausible mechanism is free-free absorption of the radio pulses by a low-density ionized wind surrounding the companion. Detailed numerical calculations are performed for this case, and it is found that all of the observations made at 430 MHz can be reliably reproduced, including the asymmetry in the excess time delay of the pulses. The model leads to definite predictions for the duration of the eclipse at other observing frequencies, as well as the radio intensity and excess time delay of the pulses as a function of orbital phase. If the duration of the eclipses were found to be independent of frequency, then the likely mechanism would be reflection of the radio signal at a contact discontinuity between a high-density wind and the pulsar radiation. In this case, however, it is difficult to explain the observed symmetry of the eclipse. 12 refs.

  1. Physical parameters of eclipsing binary components, discovered by STEREO

    NASA Astrophysics Data System (ADS)

    Belcheva, Maya; Markov, Haralambi; Tsvetanov, Zlatan; Iliev, Ilian; Stateva, Ivanka

    2015-01-01

    Using photometric observations made with the Heliospheric Imager 1 onboard NASA's STEREO mission a list of eclipsing binary systems was prepared which can be observed with the Coude spectrograph of the National Astronomical Observatory of Bulgaria, Smolyan, Bulgaria. The epoch and orbital period of each system were determined. The full complement of data consist of light curves extracted from STEREO HI-1 cameras photometry, wide coverage Echelle spectra obtained with the ARCES spectrograph at Apache Point Observatory, New Mexico, USA, for stellar characterization and Coude spectra with R ≈ 15000 and R ≈ 30000 obtained at NAO Rozhen for radial velocity curves. Here we present preliminary results from applying the Wilson-Devinney models for the determination of some physical parameters of three SB2 eclipsing binary systems - HD 103694, HD 185990, and HD 214688.

  2. Searching Kepler Variable Stars with the Eclipsing Binary Factory Pipeline

    NASA Astrophysics Data System (ADS)

    Parvizi, Mahmoud; Paegert, M.

    2014-01-01

    Repositories of large survey data, such as the Mikulski Archive for Space Telescopes, provide an ideally sized sample from which to identify astrophysically interesting eclipsing binary systems (EBs). However, constraints on the rate of human analysis in solving for the characteristic parameters make mining this data using classical techniques prohibitive. The Kepler data set provides both the high precision simple aperture photometry necessary to detect EBs and a corresponding Kepler Eclipsing Binary Catalog - V3 (KEBC3) of 2,406 EBs in the Kepler filed of view (FoV) as a benchmark. We developed a fully automated end-to-end computational pipeline known as the Eclipsing Binary Factory (EBF) that employs pre-classification data processing modules, a feed-forward single layer perception neural network classifier (NNC), and a subsequent neural network solution estimator (NNSE). This paper focuses on the EBF component modules to include NNC, but excludes the NNSE, as a precursor to a fully automated pipeline that uses solution estimates of characteristic parameters to identify astrophysically interesting EBs. The EBF was found to recover ~94% of KEBC3 EBs contained in the Kepler “Q3” data release where the period is less than thirty days.

  3. Fundamental Parameters of Kepler Eclipsing Binaries. I. KIC 5738698

    NASA Astrophysics Data System (ADS)

    Matson, Rachel A.; Gies, Douglas R.; Guo, Zhao; Orosz, Jerome A.

    2016-06-01

    Eclipsing binaries serve as a valuable source of stellar masses and radii that inform stellar evolutionary models and provide insight into additional astrophysical processes. The exquisite light curves generated by space-based missions such as Kepler offer the most stringent tests to date. We use the Kepler light curve of the 4.8 day eclipsing binary KIC 5739896 with ground based optical spectra to derive fundamental parameters for the system. We reconstruct the component spectra to determine the individual atmospheric parameters, and model the Kepler photometry with the binary synthesis code Eclipsing Light Curve to obtain accurate masses and radii. The two components of KIC 5738698 are F-type stars with {M}1\\=\\1.39+/- 0.04 {M}ȯ , {M}2\\=\\1.34+/- 0.06 {M}ȯ , and {R}1\\=\\1.84+/- 0.03 {R}ȯ , {R}2\\=\\1.72+/- 0.03 {R}ȯ . We also report a small eccentricity (e≲ 0.0017) and unusual albedo values that are required to match the detailed shape of the Kepler light curve. Comparison with evolutionary models indicate an approximate age of 2.3 Gyr for the system.

  4. On the eclipsing binary ELHC 10 with occulting dark disc in the Large Magellanic Cloud

    NASA Astrophysics Data System (ADS)

    Garrido, H. E.; Mennickent, R. E.; Djurašević, G.; Schmidtobreick, L.; Graczyk, D.; Villanova, S.; Barría, D.

    2016-04-01

    We investigate the luminous star ELHC 10 located in the bar of the Large Magellanic Cloud (LMC), concluding that it is a SB1 long-period eclipsing binary where the main eclipse is produced by an opaque structure hiding the secondary star. For the more luminous component we determine an effective temperature of 6500 ± 250 K, log g = 1.0 ± 0.5 and luminosity 5970 L⊙. From the radial velocities of their photospheric lines, we calculate a mass function of 7.37 ± 0.55 M⊙. Besides Balmer and forbidden N II emission, we find splitting of metallic lines, characterized by strong discrete absorption components, alternatively seen at the blue and red side of the photospheric spectrum. These observations hardly can be interpreted in terms of an structured atmosphere but might reflect mass streams in an interacting binary. The primary shows signatures of s-process nucleosynthesis and might be a low-mass post-asymptotic giant branch star with a rare evolutionary past if the binary is semidetached. The peak separation and constancy of radial velocity in H α suggest that most of the Balmer emission comes from a circumbinary disc.

  5. FORMATION OF BLACK WIDOWS AND REDBACKS—TWO DISTINCT POPULATIONS OF ECLIPSING BINARY MILLISECOND PULSARS

    SciTech Connect

    Chen, Hai-Liang; Chen, Xuefei; Han, Zhanwen; Tauris, Thomas M.

    2013-09-20

    Eclipsing binary millisecond pulsars (MSPs; the so-called black widows and redbacks) can provide important information about accretion history, pulsar irradiation of their companion stars, and the evolutionary link between accreting X-ray pulsars and isolated MSPs. However, the formation of such systems is not well understood, nor the difference in progenitor evolution between the two populations of black widows and redbacks. Whereas both populations have orbital periods between 0.1 and 1.0 days, their companion masses differ by an order of magnitude. In this paper, we investigate the formation of these systems via the evolution of converging low-mass X-ray binaries by employing the MESA stellar evolution code. Our results confirm that one can explain the formation of most of these eclipsing binary MSPs using this scenario. More notably, we find that the determining factor for producing either black widows or redbacks is the efficiency of the irradiation process, such that the redbacks absorb a larger fraction of the emitted spin-down energy of the radio pulsar (resulting in more efficient mass loss via evaporation) compared to that of the black widow systems. We argue that geometric effects (beaming) are responsible for the strong bimodality of these two populations. Finally, we conclude that redback systems do not evolve into black widow systems with time.

  6. Searching for pulsations in Kepler eclipsing binary stars

    NASA Astrophysics Data System (ADS)

    Gaulme, Patrick; Guzik, Joyce A.

    2014-02-01

    Eclipsing binaries can in principle provide additional constraints to facilitate asteroseismology of one or more pulsating components. We have identified 94 possible eclipsing binary systems in a sample of over 1800 stars observed in long cadence as part of the Kepler Guest Observer Program to search for γ Doradus and δ Scuti star candidates. We show the results of a procedure to fold the light curve to identify the potential binary period, subtract a fit to the binary light curve, and perform a Fourier analysis on the residuals to search for pulsation frequencies that may arise in one or both of the stellar components. From this sample, we have found a large variety of light curve types; about a dozen stars show frequencies consistent with δ Sct or γ Dor pulsations, or light curve features possibly produced by stellar activity (rotating spots). For several stars, the folded candidate `binary' light curve resembles more closely that of an RR Lyr, Cepheid, or high-amplitude δ Sct star. We show highlights of our results and discuss the potential for asteroseismology of the most interesting objects.

  7. Tidal capture formation of low-mass X-ray binaries from wide binaries in the field

    NASA Astrophysics Data System (ADS)

    Michaely, Erez; Perets, Hagai B.

    2016-06-01

    We present a dynamical formation scenario for low mass X-ray binaries (LMXBs) in the field, focusing on black hole (BH) LMXBs. In this formation channel, LMXBs are formed from wide binaries (>1000 au) with a BH component and a stellar companion. The wide binary is perturbed by fly-bys of field stars, its orbit random walks, until driven into a sufficiently eccentric orbit such that the binary components tidally interact and the binary evolves to become a short period binary, which eventually evolves into an LMXB. We consider several models for the formation and survival of such wide binaries, and calculate the LMXB formation rates for each model. We find that models where BHs form through direct collapse with no/little natal kicks can give rise to high formation rates comparable with those inferred from observations. This formation scenario had several observational signatures: (1) the number density of LMXBs generally follows the background stellar density, beside the densest regions, where the dependence is stronger, (2) the mass function of the BH stellar companion should be comparable to the mass function of the background stellar population, likely peaking at 0.4-0.6 M⊙, and (3) the LMXBs orbit should not correlate with the spin of the BH. These aspects generally differ from the expectations from previously suggested LMXB formation models following common envelope binary stellar evolution. We note that neutron star LMXBs can similarly form from wide binaries, but their formation rate through this channel is likely significantly smaller due to their much higher natal kicks.

  8. Spectroscopy of Low Mass X-Ray Binaries: New Insights into Accretion

    NASA Technical Reports Server (NTRS)

    Vrtilek, Saeqa Dil; Mushotzky, Richard F. (Technical Monitor)

    2002-01-01

    This project is to observe two low mass X-ray binaries, chosen for their X-ray brightness, low column density, and diversity of accretion behavior. The high spectral resolution of the RGS, the broad energy range and tremendous collecting power of EPIC, and simultaneous optical monitoring with the OM are particularly well-suited to these studies. The second of two objects was not observed until September of 2002. Data analysis for the new observation is underway. over the next year we will: investigate the physical conditions of the emitting gas using emission and recombination line diagnostics to determine temperatures, densities, elemental abundances, and ionization structure; study the behavior of emission features as a function of binary orbit; and test and improve models of X-ray line emission developed by us over the past decade. We will gain insight on both the geometry of the accretion flow and on the evolutionary history of LMXBs.

  9. Spectroscopy of Low Mass X-Ray Binaries: New Insights into Accretion. Revised

    NASA Technical Reports Server (NTRS)

    DilVrtilek, Saeqa; Mushotzky, Richard (Technical Monitor)

    2001-01-01

    This project is to observe two low mass X-ray binaries, chosen for their X-ray brightness, low column density, and diversity of accretion behavior. The high spectral resolution of the RGS, the broad energy range and tremendous collecting power of EPIC, and simultaneous optical monitoring with the OM are particularly well-suited to these studies. observation of one of the two objects has taken place and the data were received in late November. The second object is yet to be observed. Over the next year we will: investigate the physical conditions of the emitting gas using emission and recombination line diagnostics to determine temperatures, densities, elemental abundances, and ionization structure; study the behavior of emission features as a function of binary orbit; and test and improve models of X-ray line emission developed by us over the past decade. We will gain insight on both the geometry of the accretion flow and on the evolutionary history of LMXBs.

  10. Sigma observations of the low mass X-ray binaries of the galactic bulge

    NASA Technical Reports Server (NTRS)

    Goldwurm, A.; Denis, M.; Paul, J.; Faisse, S.; Roques, J. P.; Bouchet, L.; Vedrenne, G.; Mandrou, P.; Sunyaev, R.; Churazov, E.

    1995-01-01

    The soft gamma-ray telescope (35-1300 keV) SIGMA aboard the high energy GRANAT space observatory has been monitoring the Galactic Bulge region for more than 2000 h of effective time since March 1990. In the resulting average 35-75 keV image we detected ten sources at a level of greater than 5 standard deviations, 6 of which can be identified with low mass X-ray binaries (LMXB). Among them, one is the 1993 X-ray nova in Ophiuchus (GRS 1726-249), one is an X-ray pulsar (GX 1+4), two are associated with X-ray bursters (GX 354-0 and A 1742-294) and two with bursting X-ray binaries in the globular clusters Terzan 2 and Terzan 1. Their spectral and long term variability behavior as measured by SIGMMA are presented and discussed.

  11. ASAS J083241+2332.4: A New Extreme Low Mass Ratio Overcontact Binary System

    NASA Astrophysics Data System (ADS)

    Sriram, K.; Malu, S.; Choi, C. S.; Vivekananda Rao, P.

    2016-03-01

    We present the R- and V-band CCD photometry and Hα line studies of an overcontact binary ASAS J083241+2332.4. The light curves exhibit totality along with a trace of the O’Connell effect. The photometric solution indicates that this system falls into the category of extreme low-mass ratio overcontact binaries with a mass ratio, q ˜ 0.06. Although a trace of the O’ Connell effect is observed, constancy of the Hα line along various phases suggest that a relatively higher magnetic activity is needed for it to show a prominent fill-in effect. The study of O-C variations reveals that the period of the binary shows a secular increase at the rate of dP/dt ˜ 0.0765 s years-1, which is superimposed by a low, but significant, sinusoidal modulation with a period of ˜8.25 years. Assuming that the sinusoidal variation is due to the presence of a third body, orbital elements have been derived. There exist three other similar systems, SX Crv, V857 Her, and E53, which have extremely low mass ratios and we conclude that ASAS J083241+2332.4 resembles SX Crv in many respects. Theoretical studies indicate that at a critical mass ratio range, qcritical = 0.07-0.09, overcontact binaries should merge and form a fast rotating star, but it has been suggested that qcritical can continue to fall up to 0.05 depending on the primary's mass and structure. Moreover, the obtained fill-out factors (50%-70%) indicate that mass loss is considerable and hydrodynamical simulations advocate that mass loss from L2 is mandatory for a successful merging process. Comprehensively, the results indicate that ASAS J083241+2332.4 is at a stage of merger. The pivotal role played by the subtle nature of the derived mass ratio in forming a rapidly rotating star has been discussed.

  12. Potential Gamma-Ray Emissions from Low-mass X-Ray Binary Jets

    NASA Astrophysics Data System (ADS)

    Zhang, Jian-Fu; Gu, Wei-Min; Liu, Tong; Xue, Li; Lu, Ju-Fu

    2015-06-01

    By proposing a pure leptonic radiation model, we study the potential gamma-ray emissions from the jets of low-mass X-ray binaries. In this model, the relativistic electrons that are accelerated in the jets are responsible for radiative outputs. Nevertheless, jet dynamics are dominated by magnetic and proton-matter kinetic energies. The model involves all kinds of related radiative processes and considers the evolution of relativistic electrons along the jet by numerically solving the kinetic equation. Numerical results show that the spectral energy distributions can extend up to TeV bands, in which synchrotron radiation and synchrotron self-Compton scattering are dominant components. As an example, we apply the model to the low-mass X-ray binary GX 339-4. The results not only can reproduce the currently available observations from GX 339-4, but also predict detectable radiation at GeV and TeV bands by the Fermi and CTA telescopes. Future observations with Fermi and CTA can be used to test our model, which could be employed to distinguish the origin of X-ray emissions.

  13. ORBITAL SOLUTIONS FOR TWO YOUNG, LOW-MASS SPECTROSCOPIC BINARIES IN OPHIUCHUS

    SciTech Connect

    Rosero, V.; Prato, L.; Wasserman, L. H.; Rodgers, B. E-mail: lprato@lowell.edu E-mail: brodgers@gemini.edu

    2011-01-15

    We report the orbital parameters for ROXR1 14 and RX J1622.7-2325Nw, two young, low-mass, and double-lined spectroscopic binaries recently discovered in the Ophiuchus star-forming region. Accurate orbital solutions were determined from over a dozen high-resolution spectra taken with the Keck II and Gemini South telescopes. These objects are T Tauri stars with mass ratios close to unity and periods of {approx}5 and {approx}3 days, respectively. In particular, RX J1622.7-2325Nw shows a non-circularized orbit with an eccentricity of 0.30, higher than any other short-period pre-main-sequence (PMS) spectroscopic binary known to date. We speculate that the orbit of RX J1622.7-2325Nw has not yet circularized because of the perturbing action of a {approx}1'' companion, itself a close visual pair. A comparison of known young spectroscopic binaries (SBs) and main-sequence (MS) SBs in the eccentricity-period plane shows an indistinguishable distribution of the two populations, implying that orbital circularization occurs in the first 1 Myr of a star's lifetime. With the results presented in this paper we increase by {approx}4% the small sample of PMS spectroscopic binary stars with known orbital elements.

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

    SciTech Connect

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

    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), 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.

  15. Deep, Low Mass Ratio Overcontact Binary Systems. VI. AH Cancri in the Old Open Cluster M67

    NASA Astrophysics Data System (ADS)

    Qian, S.-B.; Liu, L.; Soonthornthum, B.; Zhu, L.-Y.; He, J.-J.

    2006-06-01

    CCD photometric light curves in the B and V bands obtained in 2001 and in the V band obtained in 2002 of AH Cnc in the old open cluster M67 are presented. It is shown that AH Cnc is a total-eclipsing binary and its light curves correspond to a typical A type according to Binnendijk's classification. The variations of the light curve around the primary minimum and second maximum were found. Our nine epochs of light minimum monitored from 2001 to 2005, including others collected from the literature, were used to create the first study of the period changes of the binary system. A cyclic oscillation with a period of 36.5 yr and an amplitude of 0.0237 days was discovered to be superposed on a continuous period increase (dP/dt=3.99×10-7 days yr-1). Weak evidence indicates that there exists another small-amplitude period oscillation (A4=0.0035 days, P4=7.75 yr). The symmetric light curves in the B and V bands obtained in 2001 were analyzed with the 2003 version of the Wilson-Devinney code. It is confirmed that AH Cnc is a deep overcontact binary system with a high degree of overcontact f=58.5%+/-4.5% and a low mass ratio of q=0.1682+/-0.0012. The existence of the third light and the cyclic period oscillation both may suggest that AH Cnc is a triple system containing an unseen third body. The tertiary component may have played an important role in the origin of the overcontact binary star by removing angular momentum from the central system, which would cause it to have a short initial orbital period and thus evolve into an overcontact configuration by angular momentum loss. The long-term period increase can be interpreted as a mass transfer from the less massive component to the more massive one. As the orbital period increases, the decrease of the mass ratio will cause it finally to evolve into a single rapid-rotating star when the system meets the more familiar criterion that the orbital angular momentum be less than 3 times the total spin angular momentum. Therefore

  16. 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.

  17. 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.

  18. Formation and Evolution of Galactic Intermediate/Low-Mass X-ray Binaries

    NASA Astrophysics Data System (ADS)

    Shao, Yong; Li, Xiang-Dong

    2015-08-01

    We investigate the formation and evolutionary sequences of Galactic intermediate- and low-mass X-ray binaries (I/LMXBs) by combining binary population synthesis (BPS) and detailed stellar evolutionary calculations. Using an updated BPS code we compute the evolution of massive binaries that leads to the formation of incipient I/LMXBs and present their distribution in the initial donor mass versus initial orbital period diagram. We then follow the evolution of the I/LMXBs until the formation of binary millisecond pulsars (BMSPs). We find that the birthrate of the I/LMXB population is in the range of 9 × 10-6-3.4 × 10-5 yr-1, compatible with that of BMSPs that are thought to descend from I/LMXBs. We show that during the evolution of I/LMXBs they are likely to be observed as relatively compact binaries with orbital periods ≲1 day and donor masses ≲0.3M⊙. The resultant BMSPs have orbital periods ranging from less than 1 day to a few hundred days. These features are consistent with observations of LMXBs and BMSPs. We also confirm the discrepancies between theoretical predictions and observations mentioned in the literature, that is, the theoretical average mass transfer rates (˜10-10 M⊙ yr-1) of LMXBs are considerably lower than observed, and the number of BMSPs with orbital periods ˜0.1-10 days is severely underestimated. These discrepancies imply that something is missing in the modeling of LMXBs, which is likely to be related to the mechanisms of the orbital angular momentum loss.

  19. THE ORIGIN OF BLACK HOLE SPIN IN GALACTIC LOW-MASS X-RAY BINARIES

    SciTech Connect

    Fragos, T.; McClintock, J. E.

    2015-02-10

    Galactic field black hole (BH) low-mass X-ray binaries (LMXBs) are believed to form in situ via the evolution of isolated binaries. In the standard formation channel, these systems survived a common envelope phase, after which the remaining helium core of the primary star and the subsequently formed BH are not expected to be highly spinning. However, the measured spins of BHs in LMXBs cover the whole range of spin parameters. We propose here that the BH spin in LMXBs is acquired through accretion onto the BH after its formation. In order to test this hypothesis, we calculated extensive grids of detailed binary mass-transfer sequences. For each sequence, we examined whether, at any point in time, the calculated binary properties are in agreement with their observationally inferred counterparts of 16 Galactic LMXBs. The ''successful'' sequences give estimates of the mass that the BH has accreted since the onset of Roche-Lobe overflow. We find that in all Galactic LMXBs with measured BH spin, the origin of the spin can be accounted for by the accreted matter, and we make predictions about the maximum BH spin in LMXBs where no measurement is yet available. Furthermore, we derive limits on the maximum spin that any BH can have depending on current properties of the binary it resides in. Finally we discuss the implication that our findings have on the BH birth-mass distribution, which is shifted by ∼1.5 M {sub ☉} toward lower masses, compared to the currently observed one.

  20. Kepler eclipsing binary stars - VI. Identification of eclipsing binaries in the K2 Campaign 0 data set

    NASA Astrophysics Data System (ADS)

    LaCourse, Daryll M.; Jek, Kian J.; Jacobs, Thomas L.; Winarski, Troy; Boyajian, Tabetha S.; Rappaport, Saul A.; Sanchis-Ojeda, Roberto; Conroy, Kyle E.; Nelson, Lorne; Barclay, Tom; Fischer, Debra A.; Schmitt, Joseph R.; Wang, Ji; Stassun, Keivan G.; Pepper, Joshua; Coughlin, Jeffrey L.; Shporer, Avi; Prša, Andrej

    2015-10-01

    The original Kepler mission observed and characterized over 2400 eclipsing binaries (EBs) in addition to its prolific exoplanet detections. Despite the mechanical malfunction and subsequent non-recovery of two reaction wheels used to stabilize the instrument, the Kepler satellite continues collecting data in its repurposed K2 mission surveying a series of fields along the ecliptic plane. Here, we present an analysis of the first full baseline K2 data release: the Campaign 0 data set. In the 7761 light curves we have identified a total of 207 EBs. Of these, 97 are new discoveries that were not previously identified. Our pixel-level analysis of these objects has also resulted in identification of several false positives (observed targets contaminated by neighbouring EBs), as well as the serendipitous discovery of two short-period exoplanet candidates. We provide catalogue cross-matched source identifications, orbital periods, morphologies and ephemerides for these eclipsing systems. We also describe the incorporation of the K2 sample into the Kepler Eclipsing Binary Catalog,§ present spectroscopic follow-up observations for a limited selection of nine systems and discuss prospects for upcoming K2 campaigns.

  1. WISE detection of the galactic low-mass X-ray binaries

    SciTech Connect

    Wang, Xuebing; Wang, Zhongxiang

    2014-06-20

    We report on the results from our search for the Wide-field Infrared Survey Explorer (WISE) detection of the Galactic low-mass X-ray binaries (LMXBs). Among 187 binaries cataloged in Liu et al., we find 13 counterparts and 2 candidate counterparts. For the 13 counterparts, 2 (4U 0614+091 and GX 339–4) have already been confirmed by previous studies to have a jet and 1 (GRS 1915+105) to have a candidate circumbinary disk, from which the detected infrared emission arose. Having collected the broadband optical and near-infrared data in the literature and constructed flux density spectra for the other 10 binaries, we identify that 3 (A0620–00, XTE J1118+480, and GX 1+4) are candidate circumbinary disk systems, 4 (Cen X-4, 4U 1700+24, 3A 1954+319, and Cyg X-2) had thermal emission from their companion stars, and 3 (Sco X-1, Her X-1, and Swift J1753.5–0127) are peculiar systems with the origin of their infrared emission rather uncertain. We discuss the results and WISE counterparts' brightness distribution among the known LMXBs, and suggest that more than half of the LMXBs would have a jet, a circumbinary disk, or both.

  2. WISE Detection of the Galactic Low-mass X-Ray Binaries

    NASA Astrophysics Data System (ADS)

    Wang, Xuebing; Wang, Zhongxiang

    2014-06-01

    We report on the results from our search for the Wide-field Infrared Survey Explorer (WISE) detection of the Galactic low-mass X-ray binaries (LMXBs). Among 187 binaries cataloged in Liu et al., we find 13 counterparts and 2 candidate counterparts. For the 13 counterparts, 2 (4U 0614+091 and GX 339-4) have already been confirmed by previous studies to have a jet and 1 (GRS 1915+105) to have a candidate circumbinary disk, from which the detected infrared emission arose. Having collected the broadband optical and near-infrared data in the literature and constructed flux density spectra for the other 10 binaries, we identify that 3 (A0620-00, XTE J1118+480, and GX 1+4) are candidate circumbinary disk systems, 4 (Cen X-4, 4U 1700+24, 3A 1954+319, and Cyg X-2) had thermal emission from their companion stars, and 3 (Sco X-1, Her X-1, and Swift J1753.5-0127) are peculiar systems with the origin of their infrared emission rather uncertain. We discuss the results and WISE counterparts' brightness distribution among the known LMXBs, and suggest that more than half of the LMXBs would have a jet, a circumbinary disk, or both.

  3. Searches for millisecond pulsations in low-mass X-ray binaries, 2

    NASA Technical Reports Server (NTRS)

    Vaughan, B. A.; Van Der Klis, M.; Wood, K. S.; Norris, J. P.; Hertz, P.; Michelson, P. F.; Paradijs, J. Van; Lewin, W. H. G.; Mitsuda, K.; Penninx, W.

    1994-01-01

    Coherent millisecond X-ray pulsations are expected from low-mass X-ray binaries (LMXBs), but remain undetected. Using the single-parameter Quadratic Coherence Recovery Technique (QCRT) to correct for unknown binary orbit motion, we have performed Fourier transform searches for coherent oscillations in all long, continuous segments of data obtained at 1 ms time resolution during Ginga observations of LMXB. We have searched the six known Z sources (GX 5-1, Cyg X-2, Sco X-1, GX 17+2, GX 340+0, and GX 349+2), seven of the 14 known atoll sources (GX 3+1. GX 9+1, GX 9+9, 1728-33. 1820-30, 1636-53 and 1608-52), the 'peculiar' source Cir X-1, and the high-mass binary Cyg X-3. We find no evidence for coherent pulsations in any of these sources, with 99% confidence limits on the pulsed fraction between 0.3% and 5.0% at frequencies below the Nyquist frequency of 512 Hz. A key assumption made in determining upper limits in previous searches is shown to be incorrect. We provide a recipe for correctly setting upper limits and detection thresholds. Finally we discuss and apply two strategies to improve sensitivity by utilizing multiple, independent, continuous segments of data with comparable count rates.

  4. Spectroscopic Orbit of the Eclipsing Binary BD +52°2009

    NASA Astrophysics Data System (ADS)

    Khalesseh, B.

    The light variability of the above system was suspected first by Schilt and Hill (1938) and its eclipsing binary nature was confirmed by Reim and Geger (1955). Photoelectric minimum times of this Algol type eclipsing binary system have been presented by many observers, Scarfe et al (1973), Pohl and Kizilimark (1975). The spectroscopic orbital elements of the brighter A0 component has been obtained from 56 radial velocities by Ebbighausen (1967). In this work new radial velocity measurements of the BD+52 ̂ 2009 system based on Reticon observations are presented. The velocity measurements themselves are based on fitting theoretical profiles generated by a physical model of the binary, to the observed cross-correlation functions (ccf). Such profiles match this function very well, much better in fact than gaussian profiles which are generally used. The procedures used here have been mentioned in a paper by Hill and Khalesseh (1991). Stars, HD154417 and HR7001 were used as the comparison stars which were successfully used in work by Khalesseh and Hill (1992). All spectrograms were obtained at the Dominion Astrophysical Observatory (DAO) of Victoria with a variety of instruments which are described in the paper by Hill et al (1994). The above system with ``c-e'' quality orbits was selected from the Eighth Catalogue of the Orbital Elements of Spectroscopic Stars (Batten et al 1989). The results show: (The ADS regrets that the array can not be depicted in ASCII.)

  5. Hydrodynamics of winds from irradiated companion stars in low-mass X-ray binaries

    NASA Technical Reports Server (NTRS)

    Tavani, Marco; London, Richard

    1993-01-01

    We study the hydrodynamics of evaporative winds driven by X-rays and/or soft gamma-rays irradiating the outer layers of companion stars in low-mass X-ray binaries (LMXBs). We consider several irradiating fluxes and spectra for LMXBs with white dwarf and main-sequence companion stars. The thermal structure of the base of the coronal region, the position of the sonic point, and the value of the mass-loss rate are calculated in the case of spherical geometry. We consider photospheric and coronal heating from both X-ray photoionization and Compton scattering of X-rays and soft gamma-rays with energy about 1 MeV possibly irradiating the companion star in LMXBs. Evaporative winds may play a relevant role for the evolution of a special class of radiation-driven LMXBs, and this study is a step toward a quantitative understanding of the mechanism driving LMXB evolution.

  6. The evolution of cataclysmic and low-mass X-ray binaries

    NASA Technical Reports Server (NTRS)

    Patterson, J.

    1984-01-01

    The observational data for the 124 cataclysmic and low-mass X-ray binaries of known orbital period are compiled. It is found that the eruption properties are very well correlated with the orbital periods, in a manner that suggests that the mass transfer is the all-important determinant of evolution and of the eruptive behavior. Transfer rates of 10 to the -11th to 10 to the -7th solar mass/year are found, which are well correlated with orbital period. It is concluded that the mechanism which drives these systems is the magnetic braking of the secondary's rotation by its own stellar wind, coupled with the enforcement of synchronous rotation by tidal friction. This permits CVs to lose sufficient angular momentum to begin mass transfer in a reasonable time and drives the mass transfer at a high rate once it begins. An account of the long-lived phases of CV evolution is given.

  7. Rapidly evolving light curves of Low Mass X-Ray Binaries

    NASA Astrophysics Data System (ADS)

    Muhli, P.; Hakala, P. J.; Hjalmarsdotter, L.; Hannikainen, D. C.; Schultz, J.

    2004-07-01

    A few Galactic Low Mass X-Ray Binaries (LMXBs) have shown drastically evolving X-ray and/or optical orbital light curves. In two short-period LMXBs, MS 1603+2600 (= UW CrB, P[orb] = 111 min) and 4U 1916-053 (see e.g. Homer et al. 2001), the variations in the light curve morphology seem to be repeating in a periodic manner. We present first results of a photometric monitoring campaign of MS 1603+2600, showing evidence of a 5-day superorbital period in this yet unclassified source. The observations also unraveled optical flares, reminiscent of type I bursts, suggesting a neutron star primary.

  8. V404 Cyg - an Interacting Black-Hole Low-Mass X-ray Binary

    NASA Astrophysics Data System (ADS)

    Fox, Ori; Mauerhan, Jon; Graham, Melissa

    2015-07-01

    This DDT proposal is prompted by the June 15, 2015 outburst of V404 Cyg, a black-hole (BH) low-mass X-ray binary (LMXB). This outburst stands out since it is the first black hole system with a measured parallax, lying at a distance of only 2.39+/-0.14 kpc. An extensive and loosely organized multi-wavelength campaign is already underway by the astronomical community. One of the missing pieces of the puzzle is the mid-infrared (IR). Combined with radio, optical, and X-ray data, the mid-IR will help to discriminate discriminate between an accretion disk, jet emission, or circumstellar dust scenarios. Spitzer offers a unique opportunity to observe at these wavelengths. Here we propose 4 very short (5-minutes at 3.6 and 4.5 micron) observations of IRAC hotometry to search for the presence of warm dust and, if present, constrain the heating mechanism.

  9. BVRI Photometry of the Eclipsing Spectroscopic Binary V1061 Cygni

    NASA Astrophysics Data System (ADS)

    Sheets, H. A.; Marschall, L. A.; Torres, G.

    2003-05-01

    A series of over 2000 images of the 9th magnitude eclipsing binary V1061 (HD235444, spectral type F8) was obtained during Autumn, 2002 using the 16-inch reflecting telescope of the Gettysburg College Observatory and a Photometrics 350 Camera equipped with a SITe 1024 x 1024 back-illuminated CCD chip. From the densely sampled BVRI light curves derived from these images, along with high-precision radial velocity data obtained at the Center for Astrophysics, we have computed a preliminary set of physical characteristics of the components of the V1061 Cygni system.

  10. Apsidal motion in eclipsing binaries: FT Ori and MZ Lac

    NASA Astrophysics Data System (ADS)

    Bulut, A.; Bulut, I.; ćiçek, C.; Erdem, A.

    2016-03-01

    In this study, the apsidal motion analysis of two eccentric eclipsing binaries, FT Ori (P = 3.150 days, e = 0.397) and MZ Lac (P = 3.158 days, e = 0.399), have been presented. Their O - C diagrams were studied using all reliable times of minima found in the literature and new values for the elements of the apsidal motion for two systems have been computed. We found long periods of apsidal motion of 538 ± 12 years and 424 ± 6 years for FT Ori and MZ Lac, respectively.

  11. Fundamental Parameters of 4 Massive Eclipsing Binaries in Westerlund 1

    NASA Astrophysics Data System (ADS)

    Bonanos, Alceste Z.; Koumpia, E.

    2011-05-01

    We present fundamental parameters of 4 massive eclipsing binaries in the young massive cluster Westerlund 1. The goal is to measure accurate masses and radii of their component stars, which provide much needed constraints for evolutionary models of massive stars. Accurate parameters can further be used to determine a dynamical lower limit for the magnetar progenitor and to obtain an independent distance to the cluster. Our results confirm and extend the evidence for a high mass for the progenitor of the magnetar. The authors acknowledge research and travel support from the European Commission Framework Program Seven under the Marie Curie International Reintegration Grant PIRG04-GA-2008-239335.

  12. KIC11560447: An Active Eclipsing Binary From the Kepler Field

    NASA Astrophysics Data System (ADS)

    Ozavci, Ibrahim; Hussain, Gaitee; Yılmaz, Mesut; O'Neal, Douglas; osman Selam, Selim; Şenavcı, Hakan Volkan

    2016-07-01

    We performed spectroscopic and photometric analysis of the detached eclipsing binary KIC11560447, in order to investigate the spot activity of the system. In this context, we reconstructed the surface maps with the help of the code DoTS, using time series spectra obtained at the 2.1m Otto Struve Telescope of the McDonald Observatory. We also analysed high precision Kepler light curves of the system simultaneously with the code DoTS to reveal the spot migration and activity behaviour.

  13. Calibrating the Updated Overshoot Mixing Model on Eclipsing Binary Stars: HY Vir, YZ Cas, χ2 Hya, and VV Crv

    NASA Astrophysics Data System (ADS)

    Meng, Y.; Zhang, Q. S.

    2014-06-01

    Detached eclipsing binary stars with convective cores provide a good tool to investigate convective core overshoot. It has been performed on some binary stars to restrict the classical overshoot model which simply extends the boundary of the fully mixed region. However, the classical overshoot model is physically unreasonable and inconsistent with helioseismic investigations. An updated model of overshoot mixing was established recently. There is a key parameter in the model. In this paper, we use observations of four eclipsing binary stars, i.e., HY Vir, YZ Cas, χ2 Hya, and VV Crv, to investigate a suitable value for the parameter. It is found that the value suggested by calibrations on eclipsing binary stars is the same as the value recommended by other methods. In addition, we have studied the effects of the updated overshoot model on the stellar structure. The diffusion coefficient of convective/overshoot mixing is very high in the convection zone, then quickly decreases near the convective boundary, and exponentially decreases in the overshoot region. The low value of the diffusion coefficient in the overshoot region leads to weak mixing and a partially mixed overshoot region. Semi-convection, which appears in the standard stellar models of low-mass stars with convective cores, is removed by partial overshoot mixing.

  14. Timing of Eclipses of Binary Stars from the ASAS Catalog

    NASA Astrophysics Data System (ADS)

    Kozlowski, S. K.; Konacki, M.; Sybilski, P.

    2011-09-01

    Light was thought of as something infinite and transcendent till 1676 when Olaus Roemer carried out precise measurements of the times of eclipses of Jovian moons. Roemer's scrupulous observations led him to a qualitative conclusion that light travels at a finite speed, at the same time providing scientists with the basics of the Light-Time Effect (LTE). LTE is observed whenever the distance between the observer and any kind of periodic event changes in time. The usual cause of this distance change is the reflex motion about the system's barycenter due to the gravitational influence of one or more additional bodies. We present results of the analysis of 5032 eclipsing contact and detached binaries from the All Sky Automated Survey (ASAS) catalogue for variations in the times of eclipses. We use an approach known from the radio pulsar timing where a template radio pulse of a pulsar is used as a reference to measure the times of arrivals of the collected pulses. Most of the variations we detect in O--Cs correspond to a linear period change, but three show evidence of more than one complete LTE-orbit. For these objects we present preliminary orbital solutions. Our results demonstrate that the timing analysis employed in radio pulsar timing can be effectively used to study large data sets from photometric surveys. This is the prelude to the analysis of data gathered by the Solaris Project which aims at the search for circumbinary planets.

  15. Phenomenological Modelling of a Group of Eclipsing Binary Stars

    NASA Astrophysics Data System (ADS)

    Andronov, Ivan L.; Tkachenko, Mariia G.; Chinarova, Lidia L.

    2016-03-01

    Phenomenological modeling of variable stars allows determination of a set of the parameters, which are needed for classification in the "General Catalogue of Variable Stars" and similar catalogs. We apply a recent method NAV ("New Algol Variable") to eclipsing binary stars of different types. Although all periodic functions may be represented as Fourier series with an infinite number of coefficients, this is impossible for a finite number of the observations. Thus one may use a restricted Fourier series, i.e. a trigonometric polynomial (TP) of order s either for fitting the light curve, or to make a periodogram analysis. However, the number of parameters needed drastically increases with decreasing width of minimum. In the NAV algorithm, the special shape of minimum is used, so the number of parameters is limited to 10 (if the period and initial epoch are fixed) or 12 (not fixed). We illustrate the NAV method by application to a recently discovered Algol-type eclipsing variable 2MASS J11080308-6145589 (in the field of previously known variable star RS Car) and compare results to that obtained using the TP fits. For this system, the statistically optimal number of parameters is 44, but the fit is still worse than that of the NAV fit. Application to the system GSC 3692-00624 argues that the NAV fit is better than the TP one even for the case of EW-type stars with much wider eclipses. Model parameters are listed.

  16. X-ray spectroscopy of low-mass X-ray binaries

    NASA Astrophysics Data System (ADS)

    Juett, Adrienne Marie

    2004-10-01

    I present high-resolution X-ray grating spectroscopy of neutron stars in low-mass X-ray binaries (LMXBs) using instruments onboard the Chandra X-ray Observatory and the X-ray Multi-Mirror Mission (XMM-Newton). The first part of this thesis concentrates on results from the subset of LMXBs with orbital periods less than an hour, known as ultracompact binaries. Previous low- resolution X-ray spectra of four systems (4U 0614+091, 2S 0918-549, 4U 1543-624, and 4U 1850-087) all contain a broad residual near 0.7 keV which had been attributed to unresolved line emission. I show that this residual is due to an incorrect model of the intervening photoelectric absorption and can be accounted for by allowing a non-standard Ne/O abundance ratio in the intervening material. I propose that there is neon-rich material local to each binary and that the mass donor is a low-mass, neon-rich degenerate dwarf in an ultracompact binary. Follow-up spectroscopy of 2S 0918-549 and 4U 1543-624 with the High Energy Transmission Grating Spectrometer (HETGS) onboard Chandra and the Reflection Grating Spectrometer onboard XMM confirms the excess neutral neon absorption. Interestingly, the Ne/O ratio of 4U 1543-624 varies by a factor of three between the Chandra and XMM observations, supporting the suggestion that some of the absorption originates local to the binaries. I also present X-ray spectroscopy of another ultracompact binary, the accretion-powered millisecond pulsar XTE J0929-314. No emission or absorption features are found in the high-resolution spectrum of this source, and the neutral absorption edge depths are consistent with the estimated interstellar absorption. The second part of this thesis uses LMXBs as probes of the interstellar medium (ISM). High-resolution X-ray studies of ISM absorption features can provide measurements of the relative abundances and ionization fractions of all the elements from carbon through iron. X-ray studies also probe the ISM on larger scales than is

  17. Revised Photometric Elements of the Eclipsing Binary Di-Pegasi

    NASA Astrophysics Data System (ADS)

    Mardirossian, F.; Predolin, F.; Giuricin, G.

    1980-11-01

    Using Wood's (1972) model we have analyzed Binnendijk's (1973) two-colour photoelectric observations - as yet unsolved - of the eclipsing binary DI Peg and the photoelectric lightcurves published by Rucin'ski (1967). Our photoelectric elements, though still in favour of a semidetached configuration considerably differ from Ruciński's previous solution. The F4 primary is accompanied by a fainter and smaller (probably late G) cooler star, which fills its Roche lobe for our photometric mass ratio q = 0.3. The absolute elements of DI Peg, tentatively estimated by assuming for the primary a mass of 1.4 Msun, reveal that the secondary appears to be clearly undermassive for its temperature, size and luminosity, like common mass-exchange cooler remnants of Algol-type binaries.

  18. Neural network analysis of W UMa eclipsing binaries

    NASA Astrophysics Data System (ADS)

    Zeraatgari, F. Z.; Abedi, A.; Farshad, M.; Ebadian, M.; Riazi, N.

    2015-04-01

    We try five different artificial neural models, four models based on PNN (Perceptron Neural Network), and one using GRNN (Generalized Regression Neural Network) as tools for the automated light curve analysis of W UMa-type eclipsing binary systems. These algorithms, which are inspired by the Rucinski method, are designed and trained using MATLAB 7.6. A total of 17,820 generated contact binary light curves are first analyzed using a truncated cosine series with 11 coefficients and the most significant coefficients are applied as inputs of the neural models. The required sample light curves are systematically generated, using the WD2007 program (Wilson and Devinney 2007). The trained neural models are then applied to estimate the geometrical parameters of seven W UMa-type systems. The efficiency of different neural network models are then evaluated and compared to find the most efficient one.

  19. 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.

  20. ORBITAL PERIOD AND OUTBURST LUMINOSITY OF TRANSIENT LOW MASS X-RAY BINARIES

    SciTech Connect

    Wu, Y. X.; Yu, W.; Li, T. P.; Maccarone, T. J.; Li, X. D.

    2010-08-01

    In this paper, we investigate the relationship between the maximal luminosity of X-ray outburst and the orbital period in transient low mass X-ray binaries (or soft X-ray transients) observed by the Rossi X-ray Timing Explorer (RXTE) in the past decade. We find that the maximal luminosity (3-200 keV) in Eddington units generally increases with increasing orbital period, which does not show a luminosity saturation but in general agrees with theoretical prediction. The peak luminosities in ultra-compact binaries might be higher than those with an orbital period of 2-4 hr, but more data are needed to make this claim. We also find that there is no significant difference in the 3-200 keV peak outburst luminosity between neutron star (NS) systems and black hole (BH) systems with orbital periods above 4 hr; however, there might be a significant difference at smaller orbital periods where only NS systems are observed and radiatively inefficient accretion flow is expected to work at low luminosities for BH accreters.

  1. Discovery and Characterization of Wide Binary Systems with a Very Low Mass Component

    NASA Astrophysics Data System (ADS)

    Baron, Frédérique; Lafrenière, David; Artigau, Étienne; Doyon, René; Gagné, Jonathan; Davison, Cassy L.; Malo, Lison; Robert, Jasmin; Nadeau, Daniel; Reylé, Céline

    2015-03-01

    We report the discovery of 14 low-mass binary systems containing mid-M to mid-L dwarf companions with separations larger than 250 AU. We also report the independent discovery of nine other systems with similar characteristics that were recently discovered in other studies. We have identified these systems by searching for common proper motion sources in the vicinity of known high proper motion stars, based on a cross-correlation of wide area near-infrared surveys (2MASS, SDSS, and SIMP). An astrometric follow-up, for common proper motion confirmation, was made with SIMON and/or CPAPIR at the Observatoire du Mont Mégantic 1.6 m and CTIO 1.5 m telescopes for all the candidates identified. A spectroscopic follow-up was also made with GMOS or GNIRS at Gemini to determine the spectral types of 11 of our newly identified companions and 10 of our primaries. Statistical arguments are provided to show that all of the systems we report here are very likely to be physical binaries. One of the new systems reported features a brown dwarf companion: LSPM J1259+1001 (M5) has an L4.5 (2M1259+1001) companion at ˜340 AU. This brown dwarf was previously unknown. Seven other systems have a companion of spectral type L0-L1 at a separation in the 250-7500 AU range. Our sample includes 14 systems with a mass ratio below 0.3.

  2. Studies of Two Massive Eclipsing Double-lined Spectroscopic Binaries

    NASA Astrophysics Data System (ADS)

    Williams, Stephen J.; Gies, D. R.; Hillwig, T. C.; McSwain, M. V.; Huang, W.

    2013-06-01

    As part of an ongoing investigation into the spectroscopic variability of massive stars, we present preliminary results for two double-lined eclipsing binary systems, HD 130146 (VZ Cen) and LS 3052 (V 1176 Cen). In our analysis we used archival Hipparcos photometry for HD 103146 and All Sky Automated Survey V-band photometry for LS 3052. All spectra were obtained from the Cerro Tololo Inter-American Observatory 1.5-m telescope. The systems were analyzed using the Eclipsing Light Curve code (ELC; Orosz & Hauschildt 2000). A combined analysis of these data yields masses, radii, effective temperatures, gravities, and estimates for the ages and distances of each system. HD 103146 is a 4.9 day binary with a slightly evolved primary (T_{eff} 28000 K and log g 3.75) while the secondary nearly fills its Roche lobe. LS 3052 has an eccentric orbit with a period of 31 days and contains both an evolved primary and secondary. Preliminary solutions indicate the primary's mass to be 33 Mo with a 21 Mo secondary.

  3. MASS CONSTRAINTS FROM ECLIPSE TIMING IN DOUBLE WHITE DWARF BINARIES

    SciTech Connect

    Kaplan, David L.

    2010-07-10

    I demonstrate that an effect similar to the Roemer delay, familiar from timing radio pulsars, should be detectable in the first eclipsing double white dwarf (WD) binary, NLTT 11748. By measuring the difference of the time between the secondary and primary eclipses from one-half period (4.6 s), one can determine the physical size of the orbit and hence constrain the masses of the individual WDs. A measurement with uncertainty <0.1 s-possible with modern large telescopes-will determine the individual masses to {+-}0.02 M{sub sun} when combined with good-quality (<1 km s{sup -1}) radial velocity data, although the eccentricity must also be known to high accuracy ({+-}10{sup -3}). Mass constraints improve as P {sup -1/2} (where P is the orbital period), so this works best in wide binaries and should be detectable even for non-degenerate stars, but such constraints require the mass ratio to differ from 1, as well as undistorted orbits.

  4. Eclipses and occultations on binary Trojan asteroid (617) Patroclus

    NASA Astrophysics Data System (ADS)

    Marchis, Franck; Berthier, Jerome; Descamps, Pascal; Emery, Josh; Harris, Alan; Hestroffer, Daniel; Mottola, Stefano; Mueller, Michael; Vachier, Frederic

    2006-05-01

    We propose to observe a combined eclipse- and occultation event of the binary asteroid system (617) Patroclus, a member of the intriguing population of Jupiter Trojans. This will be the first thermal-IR observation of such a rare event. Patroclus, the only known Trojan binary, is a particularly well-suited target because its orbital parameters are well known (Marchis et al. 2006) and both components are of roughly equal size, which maximizes the observable effects of the eclipse event. Observing a nearly total eclipse allows the surface thermal inertia, which depends on key physical properties such as the surface porosity, to be determined in a uniquely direct way. Also, occultations allow one component to be studied without significant contamination from the other, thereby facilitating the determination of possible differences between their surface compositions. Note that the angular distance between the components does not exceed 0.15". The proposed Spitzer IRS observations will allow us to clarify the physical nature of the Patroclus system and constrain its mineralogy by providing measurements of the thermal inertia, size and albedo of each component, and the spectral silicate features around 10microns. From spatially resolved Keck imaging Marchis et al. (2006) have recently determined the orbital parameters of the Patroclus system. From these they determined the total mass of the system which, combined with a previous estimate of Patroclus' size, implies a bulk mass density of only 0.8 g cm-3, indicative of a composition dominated by water ice. This supports the idea that large Jupiter Trojans, such as Patroclus, are among the most primordial bodies in the solar system accessible to observations, and that they are basically collisionally unaltered since their formation.

  5. 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.

  6. DISCOVERY OF PSR J1227−4853: A TRANSITION FROM A LOW-MASS X-RAY BINARY TO A REDBACK MILLISECOND PULSAR

    SciTech Connect

    Roy, Jayanta; Bhattacharyya, Bhaswati; Stappers, Ben; Ray, Paul S.; Wolff, Michael; Wood, Kent S.; Chengalur, Jayaram N.; Deneva, Julia; Camilo, Fernando; Johnson, Tyrel J.; Hessels, Jason W. T.; Bassa, Cees G.; Keane, Evan F.; Ferrara, Elizabeth C.; Harding, Alice K.

    2015-02-10

    XSS J12270−4859 is an X-ray binary associated with the Fermi Large Area Telescope gamma-ray source 1FGL J1227.9−4852. In 2012 December, this source underwent a transition where the X-ray and optical luminosity dropped and the spectral signatures of an accretion disk disappeared. We report the discovery of a 1.69 millisecond pulsar (MSP), PSR J1227−4853, at a dispersion measure of 43.4 pc cm{sup −3} associated with this source, using the Giant Metrewave Radio Telescope (GMRT) at 607 MHz. This demonstrates that, post-transition, the system hosts an active radio MSP. This is the third system after PSR J1023+0038 and PSR J1824−2452I showing evidence of state switching between radio MSP and low-mass X-ray binary states. We report timing observations of PSR J1227−4853 with the GMRT and Parkes, which give a precise determination of the rotational and orbital parameters of the system. The companion mass measurement of 0.17–0.46 M{sub ⊙} suggests that this is a redback system. PSR J1227−4853 is eclipsed for about 40% of its orbit at 607 MHz with additional short-duration eclipses at all orbital phases. We also find that the pulsar is very energetic, with a spin-down luminosity of ∼10{sup 35} erg s{sup −1}. We report simultaneous imaging and timing observations with the GMRT, which suggests that eclipses are caused by absorption rather than dispersion smearing or scattering.

  7. Formation of Black Hole Low-mass X-Ray Binaries in Hierarchical Triple Systems

    NASA Astrophysics Data System (ADS)

    Naoz, Smadar; Fragos, Tassos; Geller, Aaron; Stephan, Alexander P.; Rasio, Frederic A.

    2016-05-01

    The formation of black hole (BH) low-mass X-ray binaries (LMXB) poses a theoretical challenge, as low-mass companions are not expected to survive the common-envelope scenario with the BH progenitor. Here we propose a formation mechanism that skips the common-envelope scenario and relies on triple-body dynamics. We study the evolution of hierarchical triples following the secular dynamical evolution up to the octupole-level of approximation, including general relativity, tidal effects, and post-main-sequence evolution such as mass loss, changes to stellar radii, and supernovae. During the dynamical evolution of the triple system the “eccentric Kozai-Lidov” mechanism can cause large eccentricity excitations in the LMXB progenitor, resulting in three main BH-LMXB formation channels. Here we define BH-LMXB candidates as systems where the inner BH-companion star crosses its Roche limit. In the “eccentric” channel (∼81% of the LMXBs in our simulations) the donor star crosses its Roche limit during an extreme eccentricity excitation while still on a wide orbit. Second, we find a “giant” LMXB channel (∼11%), where a system undergoes only moderate eccentricity excitations but the donor star fills its Roche-lobe after evolving toward the giant branch. Third, we identify a “classical” channel (∼8%), where tidal forces and magnetic braking shrink and circularize the orbit to short periods, triggering mass-transfer. Finally, for the giant channel we predict an eccentric (∼0.3–0.6) preferably inclined (∼40°, ∼140°) tertiary, typically on a wide enough orbit (∼104 au) to potentially become unbound later in the triple evolution. While this initial study considers only one representative system and neglects BH natal kicks, we expect our scenario to apply across a broad region of parameter space for triple-star systems.

  8. Red Giants in Eclipsing Binaries as a Benchmark for Asteroseismology

    NASA Astrophysics Data System (ADS)

    Rawls, Meredith L.

    2016-04-01

    Red giants with solar-like oscillations are astrophysical laboratories for probing the Milky Way. The Kepler Space Telescope revolutionized asteroseismology by consistently monitoring thousands of targets, including several red giants in eclipsing binaries. Binarity allows us to directly measure stellar properties independently of asteroseismology. In this dissertation, we study a subset of eight red giant eclipsing binaries observed by Kepler with a range of orbital periods, oscillation behavior, and stellar activity. Two of the systems do not show solar-like oscillations at all. We use a suite of modeling tools to combine photometry and spectroscopy into a comprehensive picture of each star's life. One noteworthy case is a double red giant binary. The two stars are nearly twins, but have one main set of solar-like oscillations with unusually low-amplitude, wide modes, likely due to stellar activity and modest tidal forces acting over the 171 day eccentric orbit. Mixed modes indicate the main oscillating star is on the secondary red clump (a core-He-burning star), and stellar evolution modeling supports this with a coeval history for a pair of red clump stars. The other seven systems are all red giant branch stars (shell-H-burning) with main sequence companions. The two non-oscillators have the strongest magnetic signatures and some of the strongest lifetime tidal forces with nearly-circular 20–34 day orbits. One system defies this trend with oscillations and a 19 day orbit. The four long-period systems (>100 days) have oscillations, more eccentric orbits, and less stellar activity. They are all detached binaries consistent with coevolution. We find the asteroseismic scaling laws are approximately correct, but fail the most for stars that are least like the Sun by systematically overestimating both mass and radius. Strong magnetic activity and tidal effects often occur in tandem and act to suppress solar-like oscillations. These red giant binaries offer an

  9. LSPM J1112+7626: DETECTION OF A 41 DAY M-DWARF ECLIPSING BINARY FROM THE MEARTH TRANSIT SURVEY

    SciTech Connect

    Irwin, Jonathan M.; Quinn, Samuel N.; Berta, Zachory K.; Latham, David W.; Torres, Guillermo; Burke, Christopher J.; Charbonneau, David; Dittmann, Jason; Esquerdo, Gilbert A.; Stefanik, Robert P.; Oksanen, Arto; Buchhave, Lars A.; Nutzman, Philip; Berlind, Perry; Calkins, Michael L.; Falco, Emilio E.

    2011-12-01

    We report the detection of eclipses in LSPM J1112+7626, which we find to be a moderately bright (I{sub C} = 12.14 {+-} 0.05) very low mass binary system with an orbital period of 41.03236 {+-} 0.00002 days, and component masses M{sub 1} = 0.395 {+-} 0.002 M{sub Sun} and M{sub 2} = 0.275 {+-} 0.001 M{sub Sun} in an eccentric (e = 0.239 {+-} 0.002) orbit. A 65 day out-of-eclipse modulation of approximately 2% peak-to-peak amplitude is seen in I-band, which is probably due to rotational modulation of photospheric spots on one of the binary components. This paper presents the discovery and characterization of the object, including radial velocities sufficient to determine both component masses to better than 1% precision, and a photometric solution. We find that the sum of the component radii, which is much better determined than the individual radii, is inflated by 3.8{sup +0.9}{sub -0.5}% compared to the theoretical model predictions, depending on the age and metallicity assumed. These results demonstrate that the difficulties in reproducing observed M-dwarf eclipsing binary radii with theoretical models are not confined to systems with very short orbital periods. This object promises to be a fruitful testing ground for the hypothesized link between inflated radii in M-dwarfs and activity.

  10. Low mass binary neutron star mergers: Gravitational waves and neutrino emission

    NASA Astrophysics Data System (ADS)

    Foucart, Francois; Haas, Roland; Duez, Matthew D.; O'Connor, Evan; Ott, Christian D.; Roberts, Luke; Kidder, Lawrence E.; Lippuner, Jonas; Pfeiffer, Harald P.; Scheel, Mark A.

    2016-02-01

    Neutron star mergers are among the most promising sources of gravitational waves for advanced ground-based detectors. These mergers are also expected to power bright electromagnetic signals, in the form of short gamma-ray bursts, infrared/optical transients powered by r-process nucleosynthesis in neutron-rich material ejected by the merger, and radio emission from the interaction of that ejecta with the interstellar medium. Simulations of these mergers with fully general relativistic codes are critical to understand the merger and postmerger gravitational wave signals and their neutrinos and electromagnetic counterparts. In this paper, we employ the Spectral Einstein Code to simulate the merger of low mass neutron star binaries (two 1.2 M⊙ neutron stars) for a set of three nuclear-theory-based, finite temperature equations of state. We show that the frequency peaks of the postmerger gravitational wave signal are in good agreement with predictions obtained from recent simulations using a simpler treatment of gravity. We find, however, that only the fundamental mode of the remnant is excited for long periods of time: emission at the secondary peaks is damped on a millisecond time scale in the simulated binaries. For such low mass systems, the remnant is a massive neutron star which, depending on the equation of state, is either permanently stable or long lived (i.e. rapid uniform rotation is sufficient to prevent its collapse). We observe strong excitations of l =2 , m =2 modes, both in the massive neutron star and in the form of hot, shocked tidal arms in the surrounding accretion torus. We estimate the neutrino emission of the remnant using a neutrino leakage scheme and, in one case, compare these results with a gray two-moment neutrino transport scheme. We confirm the complex geometry of the neutrino emission, also observed in previous simulations with neutrino leakage, and show explicitly the presence of important differences in the neutrino luminosity, disk

  11. Results of ongoing Swift/XRT monitoring of the low mass X-ray binary IGR J17091-3624

    NASA Astrophysics Data System (ADS)

    Ballhausen, Ralf; Grinberg, Victoria; Wilms, Joern; Fuerst, Felix; Eikmann, Wiebke; Bozzo, Enrico; Cadolle Bel, Marion; Egron, Elise; Favre, Thierry; Ferrigno, Carlo; Krauss, Felicia; Kreykenbohm, Ingo; Nowak, Michael A.; Pottschmidt, Katja; Rodriguez, Jerome; Bachetti, Matteo

    2016-03-01

    The low mass X-ray binary IGR J17091-3624 has been reported to be in outburst by Miller et al. (ATel #8742) on 2016 February 26. Subsequent observations by Swift/XRT and INTEGRAL revealed the transient to be in the hard/low state (Grinberg et al., ATel #8761).

  12. Low-mass X-Ray Binaries and Globular Clusters Streamers and Arcs in NGC 4278

    NASA Astrophysics Data System (ADS)

    D'Abrusco, R.; Fabbiano, G.; Brassington, N. J.

    2014-03-01

    We report significant inhomogeneities in the projected two-dimensional spatial distributions of low-mass X-ray binaries (LMXBs) and globular clusters (GCs) of the intermediate mass elliptical galaxy NGC 4278. In the inner region of NGC 4278, a significant arc-like excess of LMXBs extending south of the center at ~50'' in the western side of the galaxy can be associated with a similar overdensity of the spatial distribution of red GCs from Brassington et al. Using a recent catalog of GCs produced by Usher et al. and covering the whole field of the NGC 4278 galaxy, we have discovered two other significant density structures outside the D 25 isophote to the W and E of the center of NGC 4278, associated with an overdensity and an underdensity, respectively. We discuss the nature of these structures in the context of the similar spatial inhomogeneities discovered in the LMXBs and GCs populations of NGC 4649 and NGC 4261, respectively. These features suggest streamers from disrupted and accreted dwarf companions.

  13. Low mass binary neutron star mergers : gravitational waves and neutrino emission

    NASA Astrophysics Data System (ADS)

    Foucart, Francois; SXS Collaboration Collaboration

    2016-03-01

    We present numerical simulations of low mass binary neutron star mergers (1 . 2M⊙ - 1 . 2M⊙) with the SpEC code for a set of three nuclear-theory based, finite temperature equations of state. The merger remnant is a massive neutron star which is either permanently stable or long-lived. We focus on the post-merger gravitational wave signal, and on neutrino-matter interactions in the merger remnant. We show that the frequency peaks of the post-merger gravitational wave signal are in good agreement with predictions obtained from simulations using a simpler treatment of gravity. We then estimate the neutrino emission of the remnant using a neutrino leakage scheme and, in one case, compare these results with a gray two-moment neutrino transport scheme. We confirm the complex geometry of the neutrino emission, also observed in previous simulations with neutrino leakage, and show explicitly the presence of important differences in the neutrino luminosity, disk composition, and outflow properties between the neutrino leakage and transport schemes. We discuss the impact of our results on our ability to measure the neutron star equation of state, and on the post-merger electromagnetic signal and r-process nucleosynthesis in neutron star mergers. Einstein Fellow.

  14. Quiescent thermal emission from neutron stars in low-mass X-ray binaries

    NASA Astrophysics Data System (ADS)

    Turlione, A.; Aguilera, D. N.; Pons, J. A.

    2015-05-01

    Context. We monitored the quiescent thermal emission from neutron stars in low-mass X-ray binaries after active periods of intense activity in X-rays (outbursts). Aims: The theoretical modeling of the thermal relaxation of the neutron star crust may be used to establish constraints on the crust composition and transport properties, depending on the astrophysical scenarios assumed. Methods: We numerically simulated the thermal evolution of the neutron star crust and compared them with inferred surface temperatures for five sources: MXB 1659-29, KS 1731-260, XTE J1701-462, EXO 0748-676 and IGR J17480-2446. Results: We find that the evolution of MXB 1659-29, KS 1731-260 and EXO 0748-676 can be well described within a deep crustal cooling scenario. Conversely, we find that the other two sources can only be explained with models beyond crustal cooling. For the peculiar emission of XTE J1701-462 we propose alternative scenarios such as residual accretion during quiescence, additional heat sources in the outer crust, and/or thermal isolation of the inner crust due to a buried magnetic field. We also explain the very recent reported temperature of IGR J17480-2446 with an additional heat deposition in the outer crust from shallow sources.

  15. A Dynamical Study of the Low Mass X-ray Binary GX 349+2

    NASA Astrophysics Data System (ADS)

    Wachter, S.

    1997-12-01

    We have obtained simultaneous optical photometry and spectroscopy of the low mass X-ray binary (and Z-source) GX 349+2 with the CTIO 0.9 m and 4 m telescopes in July 1997. The spectrum of GX 349+2 only shows strong, narrow Hα emission. The observed radial velocities indicate that our previously reported 22 hour photometric modulation is indeed the orbital period. We find gamma =-250+/-10 km s(-1) and K=65+/-6 km s(-1) for the systemic and semi-amplitude velocities respectively. The photometric light curve and radial velocity curve are offset by 0.25 in phase. Doppler tomography shows the Hα emission centered on the position of the neutron star. The relative phasing implies that the photometric variability is probably caused by the heated face of the companion star while the Hα emission may arise in an accretion disk and traces the motion of the neutron star. It also indicates that the emission region is symmetric around the neutron star. If the Hα emission does originate in the accretion disk, the narrowness of the line suggests a low inclination for the system.

  16. Absolute properties of the eclipsing binary star IM Persei

    SciTech Connect

    Lacy, Claud H. Sandberg; Torres, Guillermo; Fekel, Francis C.; Muterspaugh, Matthew W.; Southworth, John E-mail: gtorres@cfa.harvard.edu E-mail: matthew1@coe.tsuniv.edu

    2015-01-01

    IM Per is a detached A7 eccentric eclipsing binary star. We have obtained extensive measurements of the light curve (28,225 differential magnitude observations) and radial velocity curve (81 spectroscopic observations) which allow us to fit orbits and determine the absolute properties of the components very accurately: masses of 1.7831 ± 0.0094 and 1.7741 ± 0.0097 solar masses, and radii of 2.409 ± 0.018 and 2.366 ± 0.017 solar radii. The orbital period is 2.25422694(15) days and the eccentricity is 0.0473(26). A faint third component was detected in the analysis of the light curves, and also directly observed in the spectra. The observed rate of apsidal motion is consistent with theory (U = 151.4 ± 8.4 year). We determine a distance to the system of 566 ± 46 pc.

  17. ABSOLUTE PROPERTIES OF THE ECLIPSING BINARY STAR V335 SERPENTIS

    SciTech Connect

    Lacy, Claud H. Sandberg; Fekel, Francis C.; Claret, Antonio E-mail: fekel@evans.tsuniv.edu

    2012-08-15

    V335 Ser is now known to be an eccentric double-lined A1+A3 binary star with fairly deep (0.5 mag) partial eclipses. Previous studies of the system are improved with 7456 differential photometric observations from the URSA WebScope and 5666 from the NFO WebScope, and 67 high-resolution spectroscopic observations from the Tennessee State University 2 m automatic spectroscopic telescope. From dates of minima, the apsidal period is about 880 years. Accurate (better than 2%) masses and radii are determined from analysis of the two new light curves and the radial velocity curve. Theoretical models match the absolute properties of the stars at an age of about 380 Myr, though the age agreement for the two components is poor. Tidal theory correctly confirms that the orbit should still be eccentric, but we find that standard tidal theory is unable to match the observed asynchronous rotation rates of the components' surface layers.

  18. ABSOLUTE PROPERTIES OF THE ECLIPSING BINARY STAR HY VIRGINIS

    SciTech Connect

    Sandberg Lacy, Claud H.; Fekel, Francis C. E-mail: fekel@evans.tsuniv.edu

    2011-12-15

    HY Vir is found to be a double-lined F0m+F5 binary star with relatively shallow (0.3 mag) partial eclipses. Previous studies of the system are improved with 7509 differential photometric observations from the URSA WebScope and 8862 from the NFO WebScope, and 68 high-resolution spectroscopic observations from the Tennessee State University 2 m automatic spectroscopic telescope, and the 1 m coude-feed spectrometer at Kitt Peak National Observatory. Very accurate (better than 0.5%) masses and radii are determined from analysis of the new light curves and radial velocity curves. Theoretical models match the absolute properties of the stars at an age of about 1.35 Gy.

  19. Population synthesis of classical low-mass X-ray binaries in the Galactic Bulge

    NASA Astrophysics Data System (ADS)

    van Haaften, L. M.; Nelemans, G.; Voss, R.; van der Sluys, M. V.; Toonen, S.

    2015-07-01

    Aims: We model the present-day population of classical low-mass X-ray binaries (LMXBs) with neutron star accretors, which have hydrogen-rich donor stars. Their population is compared with that of hydrogen-deficient LMXBs, known as ultracompact X-ray binaries (UCXBs). We model the observable LMXB population and compare it to observations. We model the Galactic Bulge because it contains a well-observed population and it is the target of the Galactic Bulge Survey. Methods: We combine the binary population synthesis code SeBa with detailed LMXB evolutionary tracks to model the size and properties of the present-day LMXB population in the Galactic Bulge. Whether sources are persistent or transient, and what their instantaneous X-ray luminosities are, is predicted using the thermal-viscous disk instability model. Results: We find a population of ~2.1 × 103 LMXBs with neutron star accretors. Of these about 15-40 are expected to be persistent (depending on model assumptions), with luminosities higher than 1035 erg s-1. About 7-20 transient sources are expected to be in outburst at any given time. Within a factor of two these numbers are consistent with the observed population of bright LMXBs in the Bulge. This gives credence to our prediction of the existence of a population of ~1.6 × 103 LMXBs with low donor masses that have gone through the period minimum, and have present-day mass transfer rates below 10-11 M⊙ yr-1. Conclusions: Even though the observed population of hydrogen-rich LMXBs in the Bulge is larger than the observed population of (hydrogen-deficient) UCXBs, the latter have a higher formation rate. While UCXBs may dominate the total LMXB population at the present time, the majority would be very faint or may have become detached and produced millisecond radio pulsars. In that case UCXBs would contribute significantly more to the formation of millisecond radio pulsars than hydrogen-rich LMXBs.

  20. ellc: Light curve model for eclipsing binary stars and transiting exoplanets

    NASA Astrophysics Data System (ADS)

    Maxted, P. F. L.

    2016-03-01

    ellc analyzes the light curves of detached eclipsing binary stars and transiting exoplanet systems. The model represents stars as triaxial ellipsoids, and the apparent flux from the binary is calculated using Gauss-Legendre integration over the ellipses that are the projection of these ellipsoids on the sky. The code can also calculate the fluxweighted radial velocity of the stars during an eclipse (Rossiter-McLaghlin effect). ellc can model a wide range of eclipsing binary stars and extrasolar planetary systems, and can enable the use of modern Monte Carlo methods for data analysis and model testing.

  1. Occultation/Eclipse Events in Binary Asteroid 1991 VH

    NASA Astrophysics Data System (ADS)

    Pravec, Petr; Wolf, Marek; Šarounová, Lenka

    1998-05-01

    We present the results of photometric observations of the Apollo asteroid 1991 VH. Its lightcurve consists of two components: the first is the rotational lightcurve with periodPs= (0.109327 ± 0.000003) d and amplitude 0.09 mag, while the second, with periodPl= (1.362 ± 0.001) d, shows two minima with depth 0.16-0.19 mag, each with a duration of about 0.10 d, and little or no variation at phases between them. We present a model of the occulting/eclipsing binary asteroid with the secondary-to-primary diameter ratiods/dp= 0.40 that explains the observed lightcurve. In this model, the primary's rotation is not synchronized with the orbital motion and produces the short-period lightcurve component (Ps). The orbital period isPl. The mutual orbit's semimajor axis is estimated to bea= (2.7 ± 0.3)dp; the eccentricity is 0.07 ± 0.02. The similarity between the lightcurve of 1991 VH and those of 1994 AW1(Pravec and Hahn,Icarus127, 431, 1997) and (3671) Dionysus (Mottolaet al.1997,IAU Circular6680) suggests that binary asteroids may be common among near-Earth asteroids. Based on the three known cases, we tentatively derive some typical characteristics of this new class of asteroids. They are mostly consistent with the hypothesis that binary asteroids are generated by tidal disruptions of weak, gravitationally bound aggregates (so-called “rubble piles”) during encounters with the Earth (Bottke and Melosh,Nature281, 51, 1996). A possible relationship between the population of binary asteroids and the belt of small near-Earth asteroids is discussed.

  2. Discovery and Characterization of Eclipsing Binary Stars and Transiting Planets in Young Benchmark Clusters: The Pleiades and Hyades

    NASA Astrophysics Data System (ADS)

    Stassun, Keivan; David, Trevor J.; Conroy, Kyle E.; Hillenbrand, Lynne; Stauffer, John R.; Pepper, Joshua; Rebull, Luisa M.; Cody, Ann Marie

    2016-06-01

    Prior to K2, only one eclipsing binary in the Pleiades was known (HD 23642). We present the discovery and characterization of three additional eclipsing binaries (EBs) in this ~120 Myr old benchmark open cluster. Unlike HD 23642, all three of the new EBs are low mass (Mtot < 1 M⊙) and thus their components are still undergoing pre-main-sequence contraction at the Pleiades age. Low mass EBs are rare, especially in the pre-main-sequence phase, and thus these systems are valuable for constraining theoretical stellar evolution models. One of the three new EBs is single-lined with a K-type primary (HII 2407). The second (HCG 76) comprises two nearly equal-mass 0.3 M⊙ stars, with masses and radii measured with precisions of better than 3% and 5%, respectively. The third (MHO 9) has an M-type primary with a secondary that is possibly quite close to the hydrogen-burning limit, but needs additional follow-up observations to better constrain its parameters. We use the precise parameters of HCG 76 to test the predictions of stellar evolution models, and to derive an independent distance to the Pleiades of 132±5 pc. Finally, we present tentative evidence for differential rotation in the primary component of the newly discovered Pleiades EB HII 2407, and we also characterize a newly discovered transiting Neptune-sized planet orbiting an M-dwarf in the Hyades.

  3. Radial Velocity Solution for Kepler Eclipsing Binary Stars from SDSS APOGEE

    NASA Astrophysics Data System (ADS)

    Clark, Joni Marie; Mason, Paul A.; Rawls, Meredith L.; Jackiewicz, Jason; SDSS NMSU FAST

    2016-06-01

    Proper characterization of binary stars is provided by high quality spectra combined with light curves allowing for precise determination of stellar masses, radii, and effective temperatures along with binary semi-major axes and eccentricities. A program to extract radial velocities of Kepler eclipsing binaries observed by SDSS APOGEE is presented. We combine the quality light curves from the Kepler telescope with high precision radial velocity measurements from SDSS APOGEE in order to characterize the binary and stellar components. We report on the first results of this program on three eclipsing binaries, KIC 6864859, KIC 6698670, and KIC 7121885.

  4. KIC 4739791: A New R CMa-type Eclipsing Binary with a Pulsating Component

    NASA Astrophysics Data System (ADS)

    Lee, Jae Woo; Kim, Seung-Lee; Hong, Kyeongsoo; Koo, Jae-Rim; Lee, Chung-Uk; Youn, Jae-Hyuck

    2016-02-01

    The Kepler light curve of KIC 4739791 exhibits partial eclipses, the inverse O’Connell effect, and multiperiodic pulsations. Including a starspot on either of the binary components, the light-curve synthesis indicates that KIC 4739791 is in detached or semi-detached configuration with both a short orbital period and a low mass ratio. Multiple frequency analyses were performed in the light residuals after subtracting the binarity effects from the original Kepler data. We detected 14 frequencies: 6 in the low-frequency region (0.1-2.3 days-1) and 8 in the high-frequency region (18.2-22.0 days-1). Among these, six high frequencies with amplitudes of 0.62-1.97 mmag were almost constant over time for 200 days. Their pulsation periods and pulsation constants are in the ranges of 0.048-0.054 days and 0.025-0.031 days, respectively. In contrast, the other frequencies may arise from the alias effects caused by the orbital frequency or combination frequencies. We propose that KIC 4739791 is a short-period R CMa binary with the lowest mass ratio in the known classical Algols and that its primary component is a δ Sct pulsating star. Only four R CMa stars have been identified, three of which exhibit δ Sct-type oscillations. These findings make KIC 4739791 an attractive target for studies of stellar interior structure and evolution.

  5. The distribution of kHz QPO frequencies in bright low mass X-ray binaries

    NASA Astrophysics Data System (ADS)

    Belloni, T.; Méndez, M.; Homan, J.

    2005-07-01

    We analyzed all published frequencies, ν1 and ν2, of the twin kilohertz quasi-periodic oscillations (kHz QPOs) in bright neutron star low-mass X-ray binaries. The two frequencies are well correlated but, contrary to recent suggestions, the frequency-frequency correlation is significantly different from a ν2 = (3/2) ν1 relation. To check whether, although not following the the 3/2 relation, the QPO frequencies cluster around a region where ν2/ν1 ≈ 3/2, we re-analyzed the Sco X-1 data that were used to report that ratio and show that, because the distribution of ratios of linearly correlated measurements is intrinsically biased, although the significance of the clustering around ν2/ν1 ≈ 3/2 previously reported in the case of Sco X-1 is formally correct, it does not provide any useful information about a possible underlying resonance mechanism in this source. Using the same data, we then show that the (unbiased) distribution of QPO frequencies is consistent with a uniform distribution at a 2.4σ level. To investigate this further, we analyzed a larger data set of Sco X-1 and four other sources, 4U 1608-52, 4U 1636-53, 4U 1728-34 and 4U 1820-30. We find that for all five sources the distribution of the kHz QPO frequencies is not uniform and has multiple peaks, which have no analogy in the distribution of points in the spectral color-color diagrams of these sources. Finally, we demonstrate that a simple random walk of the QPO frequencies can reproduce qualitatively the observed distributions in frequency and frequency ratio. This result weakens the support for resonance models of kHz QPOs in neutron stars.

  6. Neutron star masses and radii from quiescent low-mass x-ray binaries

    SciTech Connect

    Lattimer, James M.; Steiner, Andrew W. E-mail: steiner3@uw.edu

    2014-04-01

    We perform a systematic analysis of neutron star radius constraints from five quiescent low-mass X-ray binaries and examine how they depend on measurements of their distances and amounts of intervening absorbing material, as well as their assumed atmospheric compositions. We construct and calibrate to published results a semi-analytic model of the neutron star atmosphere which approximates these effects for the predicted masses and radii. Starting from mass and radius probability distributions established from hydrogen-atmosphere spectral fits of quiescent sources, we apply this model to compute alternate sets of probability distributions. We perform Bayesian analyses to estimate neutron star mass-radius curves and equation of state (EOS) parameters that best-fit each set of distributions, assuming the existence of a known low-density neutron star crustal EOS, a simple model for the high-density EOS, causality, and the observation that the neutron star maximum mass exceeds 2 M {sub ☉}. We compute the posterior probabilities for each set of distance measurements and assumptions about absorption and composition. We find that, within the context of our assumptions and our parameterized EOS models, some absorption models are disfavored. We find that neutron stars composed of hadrons are favored relative to those with exotic matter with strong phase transitions. In addition, models in which all five stars have hydrogen atmospheres are found to be weakly disfavored. Our most likely models predict neutron star radii that are consistent with current experimental results concerning the nature of the nucleon-nucleon interaction near the nuclear saturation density.

  7. The nature of the Cygnus X-2 like Low Mass X-ray Binaries

    NASA Astrophysics Data System (ADS)

    Gibiec, Andrzej; Balucinska-Church, Monika; Church, Michael

    We propose a physical model of the Cygnus X-2 like Z-track sources: GX 340+0, GX 5-1 and Cygnus X-2 based on the results of applying a particular emission model for low mass X-ray binaries to high quality Rossi-XTE data on the sources. In this emission model the Comptonizing Accretion Disk Corona is very extended, and the evidence for this is now very secure. In our physical model, the Normal Branch is dominated by an increasing mass accretion rate between the soft and hard apex leading to a much increased neutron star temperature resulting in high radiation pressure of the neutron star. The radiation pressure continues to increase on the Horizontal Branch becoming several times super-Eddington. We propose that this disrupts the inner accretion disk and that part of the accretion flow is diverted vertically forming jets which are detected by their radio emission on this part of the Z-track. We thus propose that high radiation pressure is the main factor responsible for the launching of jets. On the Flaring Branch there is a large increase in the neutron star blackbody luminosity at constant mass accretion rate showing that there is an additional energy source on the neutron star. We find good agreement between the mass accretion rate per unit emitting area of the neutron star at the onset of flaring and the theoretical critical value at which burning becomes unstable and propose that flaring in the Cygnus X-2 like sources consists of unstable nuclear burning. Correlation of kilohertz QPO frequencies in all three sources with spectral fitting results leads to the proposal that the upper kHz QPO always takes place at the inner accretion disk edge, the radius of which increases due to disruption of the disk by the high radiation pressure.

  8. Dip Spectroscopy of the Low Mass X-Ray Binary XB 1254-690

    NASA Technical Reports Server (NTRS)

    Smale, Alan P.; Church, M. J.; BalucinskaChurch, M.; White, Nicholas E. (Technical Monitor)

    2002-01-01

    We observed the low mass X-ray binary XB 1254-690 with the Rossi X-ray Timing Explorer in 2001 May and December. During the first observation strong dipping on the 3.9-hr orbital period and a high degree of variability were observed, along with "shoulders" approx. 15% deep during extended intervals on each side of the main dips. The first observation also included pronounced flaring activity. The non-dip spectrum obtained using the PCA instrument was well-described by a two-component model consisting of a blackbody with kT = 1.30 +/- 0.10 keV plus a cut-off power law representation of Comptonized emission with power law photon index 1.10 +/- 0.46 and a cut-off energy of 5.9(sup +3.0, sub -1.4) keV. The intensity decrease in the shoulders of dipping is energy-independent, consistent with electron scattering in the outer ionized regions of the absorber. In deep dipping the depth of dipping reached 100%, in the energy band below 5 keV, indicating that all emitting regions were covered by absorber. Intensity-selected dip spectra were well-fit by a model in which the point-like blackbody is rapidly covered, while the extended Comptonized emission is progressively overlapped by the absorber, with the, covering fraction rising to 95% in the deepest portion of the dip. The intensity of this component in the dip spectra could be modeled by a combination of electron scattering and photoelectric absorption. Dipping did not occur during the 2001 December observation, but remarkably, both bursting and flaring were observed contemporaneously.

  9. The first Doppler images of the eclipsing binary SZ Piscium

    NASA Astrophysics Data System (ADS)

    Xiang, Yue; Gu, Shenghong; Cameron, A. Collier; Barnes, J. R.; Zhang, Liyun

    2016-02-01

    We present the first Doppler images of the active eclipsing binary system SZ Psc, based on the high-resolution spectral data sets obtained in 2004 November and 2006 September-December. The least-squares deconvolution technique was applied to derive high signal-to-noise profiles from the observed spectra of SZ Psc. Absorption features contributed by a third component of the system were detected in the LSD profiles at all observed phases. We estimated the mass and period of the third component to be about 0.9 M⊙ and 1283 ± 10 d, respectively. After removing the contribution of the third body from the least-squares deconvolved profiles, we derived the surface maps of SZ Psc. The resulting Doppler images indicate significant star-spot activities on the surface of the K subgiant component. The distributions of star-spots are more complex than that revealed by previous photometric studies. The cooler K component exhibited pronounced high-latitude spots as well as numerous low- and intermediate-latitude spot groups during the entire observing seasons, but did not show any large, stable polar cap, different from many other active RS CVn-type binaries.

  10. The Araucaria project. Precise physical parameters of the eclipsing binary IO Aquarii

    NASA Astrophysics Data System (ADS)

    Graczyk, D.; Maxted, P. F. L.; Pietrzyński, G.; Pilecki, B.; Konorski, P.; Gieren, W.; Storm, J.; Gallenne, A.; Anderson, R. I.; Suchomska, K.; West, R. G.; Pollacco, D.; Faedi, F.; Pojmański, G.

    2015-09-01

    Aims: Our aim is to precisely measure the physical parameters of the eclipsing binary IO Aqr and derive a distance to this system by applying a surface brightness - colour relation. Our motivation is to combine these parameters with future precise distance determinations from the Gaia space mission to derive precise surface brightness - colour relations for stars. Methods: We extensively used photometry from the Super-WASP and ASAS projects and precise radial velocities obtained from HARPS and CORALIE high-resolution spectra. We analysed light curves with the code JKTEBOP and radial velocity curves with the Wilson-Devinney program. Results: We found that IO Aqr is a hierarchical triple system consisting of a double-lined short-period (P = 2.37 d) spectroscopic binary and a low-luminosity and low-mass companion star orbiting the binary with a period of ≳25 000 d (≳70 yr) on a very eccentric orbit. We derive high-precision (better than 1%) physical parameters of the inner binary, which is composed of two slightly evolved main-sequence stars (F5 V-IV + F6 V-IV) with masses of M1 = 1.569 ± 0.004 and M2 = 1.655 ± 0.004 M⊙ and radii R1 = 2.19 ± 0.02 and R2 = 2.49 ± 0.02 R⊙. The companion is most probably a late K-type dwarf with mass ≈0.6 M⊙. The distance to the system resulting from applying a () surface brightness - colour relation is 255 ± 6 (stat.) ± 6 (sys.) pc, which agrees well with the Hipparcos value of 270+91-55 pc, but is more precise by a factor of eight.

  11. A search for eclipsing binaries in galactic globular clusters

    NASA Astrophysics Data System (ADS)

    von Braun, Kaspar

    2002-09-01

    We report on the discovery and analysis of short-period (0.1 days < P < 5 days), photometrically varying binary stars around and below the main-sequence turnoff of the globular clusters (GCs) NGC 3201, M10, & M12. These eclipsing binaries (EBs) may be used to determine directly the distances to GCs and constrain the Population II stellar main-sequence masses. During our search for binaries, we discovered the signature of differential reddening across the cluster fields which was especially strong for NGC 3201 and M10. We correct for this differential reddening by calculating average EV-I values for stars in small subregions of the field with respect to a fiducial region, which significantly improves the appearance of the GC color-magnitude diagrams (CMDs). The reddening zero point to be added to the differential value is determined by isochrone fitting. The results of our differential dereddening are presented in the form of high-resolution extinction maps. Our search for EBs returned 14 variable stars (11 EBs) in the field of NGC 3201, 3 variables (1 EB) in M10, and 2 EBs in M12. Of these variables, only one EB in NGC 3201 (a blue straggler W Ursa Majoris contact system) is a definite GC-member, based on spectroscopic observations. Another W UMa contact EB in M12 is most likely a member of M12, based on its location in the color-magnitude diagram (CMD) and its empirically calculated absolute magnitude. We present the phased lightcurves for all variables, estimate their distances and GC membership, and show their locations in the GC fields and CMDs, as well as the spectra of the NGC 3201 EBs. Finally, we discuss the implications of our results and outline future work.

  12. The Masses and Radii of the Eclipsing Binary zeta Aurigae

    NASA Astrophysics Data System (ADS)

    Bennett, Philip D.; Harper, Graham M.; Brown, Alexander; Hummel, Christian A.

    1996-11-01

    We present a full determination of the fundamental stellar and orbital parameters of the eclipsing binary ζ Aurigae (K4 Ib + BS V) using recent observations with the Hubble Space Telescope Goddard High Resolution Spectrograph (GHRS) and the Mark III long-baseline optical interferometer. The information obtained from spectroscopic and interferometric measurements is complementary, and the combination permits a complete determination of the stellar masses, the absolute semimajor axis of the orbit, and the distance. A complete solution requires that both components be visible spectroscopically, and this has always been difficult for the ζ Aur systems. The ζ Aur K star primary presents no difficulty, and accurate radial velocities are readily obtainable in the optical. However, the B star secondary is more problematic. Ground-based radial velocity measurements are hampered by the difficulty of working with the composite spectrum in the blue-violet region, the small number of suitable lines in the generally featureless optical spectrum of the B star, and the great width of the few available lines (the Balmer lines of hydrogen and a few weak He I lines) due to rapid rotation. We avoid the worst of these problems by using GHRS observations in the ultraviolet, where the K star flux is negligible and the intrinsic B star spectrum is more distinctive, and obtain the most accurate determination of the B star radial velocity amplitude to date. We also analyze published photometry of previous eclipses and near-eclipse phases of ζ Aur in order to obtain eclipse durations, which fix the length of the eclipse chord and therefore determine the orbit inclination. The long-baseline interferometry (LBI) yields, in conjunction with the spectroscopic solution, the distance to the system and thus the absolute stellar radius of the resolved K supergiant primary star, ζ Aur A. The secondary is not resolved by LBI, but its angular (and absolute) radius is found by fitting the model

  13. Analysis of the Spitzer/MIPS24 Light Curve of the M-Dwarf Eclipsing Binary GU Boo

    NASA Astrophysics Data System (ADS)

    von Braun, Kaspar; van Belle, G. T.; Ciardi, D. R.; Wachter, S.; Hoard, D. W.

    2006-12-01

    We present a carefully controlled set of Spitzer 24 micron MIPS time series observations of the M-dwarf eclipsing binary star GU Bootes. These observations serve to characterize the MIPS-24 observing techniques of the spacecraft, precisely establishing the photometric repeatability of this instrument at the tens of microJy level. The data aim to substantiate the previously reported and upcoming observations of extrasolar planet transits at similar flux levels. A further science return is the long wavelength (and thus limb darkening-independent) characterization of such a low-mass object's light curve, allowing for improved characterization of the components' linear radii and other aspects of their surface morphologies. In this presentation, we show GU Boo's 24 micron light curve and give our estimates concerning astrophysical parameters of the binary system. We furthermore give a detailed description of our analysis methods and discuss the comparison between our results and previous optical studies of this system.

  14. A Photometric Study of the Eclipsing Binary Star V958 Monocerotis

    NASA Astrophysics Data System (ADS)

    Michaels, E. J.

    2016-06-01

    Presented are new precision multi-band observations for the eclipsing binary V958 Mon. The orbital period is less than 0.3d and the light curves exhibit total eclipses. A new ephemeris was determined and a simultaneous 4-color light curve solution was obtained with the Wilson-Devinney program. The geometric and photometric elements derived are consistent with a W-type contact binary.

  15. Collective Properties of Neutron-star X-Ray Binary Populations of Galaxies. II. Pre-low-mass X-Ray Binary Properties, Formation Rates, and Constraints

    NASA Astrophysics Data System (ADS)

    Bhadkamkar, H.; Ghosh, P.

    2014-04-01

    We continue our exploration of the collective properties of neutron-star X-ray binaries in the stellar fields (i.e., outside globular clusters) of normal galaxies. In Paper I of this series, we considered high-mass X-ray binaries (HMXBs). In this paper (Paper II), we consider low-mass X-ray binaries (LMXBs), whose evolutionary scenario is very different from that of HMXBs. We consider the evolution of primordial binaries up to the stage where the neutron star just formed in the supernova explosion of the primary is in a binary with its low-mass, unevolved companion, and this binary has circularized tidally, producing what we call a pre-low-mass X-ray binary (pre-LMXB). We study the constraints on the formation of such pre-LMXBs in detail (since these are low-probability events), and calculate their collective properties and formation rates. To this end, we first consider the changes in the binary parameters in the various steps involved, viz., the common-envelope phase, the supernova, and the tidal evolution. This naturally leads to a clarification of the constraints. We then describe our calculation of the evolution of the distributions of primordial binary parameters into those of pre-LMXB parameters, following the standard evolutionary scenario for individual binaries. We display the latter as both bivariate and monovariate distributions, discuss their essential properties, and indicate the influences of some essential factors on these. Finally, we calculate the formation rate of these pre-LMXBs. The results of this paper will be used in a subsequent one to compute the expected X-ray luminosity function of LMXBs.

  16. Suzaku spectra of the neutron-star low-mass X-ray binary 4U 1608-52

    NASA Astrophysics Data System (ADS)

    Lei, Yajuan; Zhang, Haotong; zhang, Yanxia

    2015-08-01

    We present the spectral analysis of the neutron-star low-mass X-ray binary 4U 1608-52 using data from four Suzaku observations in 2010 March. 4U 1608-52 is a transient atoll source, and the analyzed observations contain the “island” and “banana” states, corresponding transitional, and soft states. The spectra are fitted with the hybrid model for the soft states, which consists of two thermal components (a multicolor accretion disk and a single-temperature blackbody) plus a broken power law. The fitting results show that the continuum spectra evolve during the different states. Fe emission line is often detected in low-mass X-ray binary, however, no obviously Fe line is detected in the four observations of 4U 1608-52.

  17. Extracting multipole moments of neutron stars from quasi-periodic oscillations in low mass X-ray binaries

    NASA Astrophysics Data System (ADS)

    Boshkayev, Kuantay; Rueda, Jorge; Muccino, Marco

    2015-06-01

    We consider the kilohertz quasi-periodic oscillations of low-mass X-ray binaries within the Hartle-Thorne spacetime. We show that the interpretation of the epicyclic frequencies of this spacetime with the observed kilohertz quasi-periodic oscillations, within the Relativistic Precession Model, allows us to extract the total mass M, angular momentum J, and quadrupole moment Q of the compact object in a low-mass X-ray binary. We exemplify this fact by analyzing the data of the Z-source GX 5-1. We show that the extracted multipole structure of the compact component of this source deviates from the one expected from a Kerr black hole and instead it points to a neutron star explanation.

  18. Coordinated X-Ray, Ultraviolet, Optical, and Radio Observations of the PSR J1023+0038 System in a Low-mass X-Ray Binary State

    NASA Astrophysics Data System (ADS)

    Bogdanov, Slavko; Archibald, Anne M.; Bassa, Cees; Deller, Adam T.; Halpern, Jules P.; Heald, George; Hessels, Jason W. T.; Janssen, Gemma H.; Lyne, Andrew G.; Moldón, Javier; Paragi, Zsolt; Patruno, Alessandro; Perera, Benetge B. P.; Stappers, Ben W.; Tendulkar, Shriharsh P.; D'Angelo, Caroline R.; Wijnands, Rudy

    2015-06-01

    The PSR J1023+0038 binary system hosts a neutron star and a low-mass, main-sequence-like star. It switches on year timescales between states as an eclipsing radio millisecond pulsar and a low-mass X-ray binary (LMXB). We present a multi-wavelength observational campaign of PSR J1023+0038 in its most recent LMXB state. Two long XMM-Newton observations reveal that the system spends ˜70% of the time in a ≈3 × 1033 erg s-1 X-ray luminosity mode, which, as shown in Archibald et al., exhibits coherent X-ray pulsations. This emission is interspersed with frequent lower flux mode intervals with ≈ 5× {10}32 erg s-1 and sporadic flares reaching up to ≈1034 erg s-1, with neither mode showing significant X-ray pulsations. The switches between the three flux modes occur on timescales of order 10 s. In the UV and optical, we observe occasional intense flares coincident with those observed in X-rays. Our radio timing observations reveal no pulsations at the pulsar period during any of the three X-ray modes, presumably due to complete quenching of the radio emission mechanism by the accretion flow. Radio imaging detects highly variable, flat-spectrum continuum radiation from PSR J1023+0038, consistent with an origin in a weak jet-like outflow. Our concurrent X-ray and radio continuum data sets do not exhibit any correlated behavior. The observational evidence we present bears qualitative resemblance to the behavior predicted by some existing “propeller” and “trapped” disk accretion models although none can account for key aspects of the rich phenomenology of this system.

  19. New Ephemeris and Model for the Eclipsing Binary DE CVn

    NASA Astrophysics Data System (ADS)

    Flora, C. T.; Ezhkova, O.; Khruzina, T.; Samus, N. N.; Wilson, R. E.

    2005-12-01

    Past photometric observations (1,2) of the eclipsing binary DE CVn have suggested that it is a white dwarf/red dwarf pair. The data show a deep (1 mag) primary minimum in the U band with a very steep ingress and egress, a much shallower (0.1 mag) primary minimum in R, and lack of a secondary minimum. In May 2005, we obtained more accurate CCD photometry in the U band with the 31" Lowell Observatory telescope. Photometric points on both branches of the eclipse and a well represented plateau at its bottom allowed for accurate determinations of the middles of the observed minima. By combining those with the times of minima from our previous observations in UBVR(2), from unpublished data of Robb & Greimel (priv. comm.), and from(1,3), we improved the ephemeris to HJD= 2450549.4697 + 0.36413865E. We used two independent programs (4,5) to model the binary. The physical and geometrical parameters obtained from the two models are similar and close to those proposed in (1), except for the position of a dark spot (or collection of small spots) needed to explain the asymmetry of the wave seen in V and R and the inequality of light in quadratures. The authors thank R.M. Robb and R. Greimel for permission to use their unpublished data. This project was supported by the NSF/REU grant AST-0354056 and the Nantucket Maria Mitchell Association. REW's participation was supported by the NSF as part of grant 0307561. References: (1) Robb, R.M. & Greimel R. 1997, IBVS, No.4486. (2) Samus, N.N., Flora, C.T., Khruzina, T., Holms, S., Ezhkova, O. & Wilson, R.E. (in prep.). (3) Tas, G. et al. 2004, IBVS, No.5548. (4) Wilson R.E., Devinney E.J. 1971, ApJ, 166, 605. (5) Khruzina, T.S. 1998, Astronomy Reports, 42, 180; Khruzina, T.S. & Cherepashchuk, A.M. 1995, Astronomy Reports, 39, 178.

  20. Estimates of black hole natal kick velocities from observations of low-mass X-ray binaries

    NASA Astrophysics Data System (ADS)

    Mandel, Ilya

    2016-02-01

    The birth kicks of black holes, arising from asymmetric mass ejection or neutrino emission during core-collapse supernovae, are of great interest for both observationally constraining supernova models and population-synthesis studies of binary evolution. Recently, several efforts were undertaken to estimate black hole birth kicks from observations of black hole low-mass X-ray binaries. We follow up on this work, specifically focusing on the highest estimated black hole kick velocities. We find that existing observations do not require black hole birth kicks in excess of approximately 80 km s-1, although higher kicks are not ruled out.

  1. Discovery of a 3.6-hr Eclipsing Luminous X-Ray Binary in the Galaxy NGC 4214

    NASA Technical Reports Server (NTRS)

    Ghosh, Kajal K.; Rappaport, Saul; Tennant, Allyn F.; Swartz, Douglas A.; Pooley, David; Madhusudhan, N.

    2006-01-01

    We report the discovery of an eclipsing X-ray binary with a 3.62-hr period within 24 arcsec of the center of the dwarf starburst galaxy NGC 4214. The orbital period places interesting constraints on the nature of the binary, and allows for a few very different interpretations. The most likely possibility is that the source lies within NGC 4214 and has an X-ray luminosity of up to 7e38. In this case the binary may well be comprised of a naked He-burning donor star with a neutron-star accretor, though a stellar-mass black-hole accretor cannot be completely excluded. There is no obvious evidence for a strong stellar wind in the X-ray orbital light curve that would be expected from a massive He star; thus, the mass of the He star should be <3-4 solar masses. If correct, this would represent a new class of very luminous X-ray binary----perhaps related to Cyg X-3. Other less likely possibilities include a conventional low-mass X-ray binary that somehow manages to produce such a high X-ray luminosity and is apparently persistent over an interval of years; or a foreground AM Her binary of much lower luminosity that fortuitously lies in the direction of NGC 4214. Any model for this system must accommodate the lack of an optical counterpart down to a limiting magnitude of 22.6 in the visible.

  2. Analysis of the Extreme Mass Ratio, High Contact Eclipsing Binary, V802 Aquilae

    NASA Astrophysics Data System (ADS)

    Samec, R. G.; Martin, M. W.; Faulkner, D. R.

    2004-05-01

    We present our observations and initial analysis of BVRI light curves of the solar type, high contact binary, V802 Aquilae [GSC 5119 948, α (2000) = 18h 58m 54.82s, δ (2000) = -03° 01' 11.5"]. The observations were taken on the evenings of 5, 6 and 8 June 2002, by RGS and DRF with the 0.9-m reflector at CTIO. Standard UBVRcIc filters were used. We took from 138 to 148 observations in each BVRI pass band and about 100 in U. Mean epochs of minimum light for one primary eclipse, HJD = 2452431.82156 (81) as well as two secondary eclipses 2452434.89764 (11) and 2452432.75617 (21) were calculated. We calculated the following linear ephemeris: J.D. Hel Min I = 2450300.43417 (69) + 0.26769479 (11) d*E. (2) The light curves are shallow (0.35 mag in V) yet show a broad time of constant light (width about 0.1 phase) in the secondary eclipse. Its depressed primary maxima (about 0.06 mag in B) suggest the presence of heavy spot activity. Our Wilson code BVRI simultaneous solution of the instrumental magnitude light curves yields a mass ratio of M2/M1 = 0.16, and a fill-out 32.7 %. The temperature difference is T2-T1 = 136 K with the tiny secondary component having the higher mean surface temperature. A 20.2° cool spot was modeled on the primary component. Its longitude, co-latitude and temperature factor were 281° , 67° , and 0.915 respectively. Further results are presented. The system is a part of a rare group of binaries with a very low mass secondary and high mass ratio that are near a phase of final coalescence into an FK Comae type star. Much of the work was done by an undergraduate student, MWM. We wish to thank Cerro Tololo InterAmerican Observatory for their allocation of observing time, and the grant from NASA administered by the American Astronomical Society.

  3. 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).

  4. Three X-ray flares near primary eclipse of the RS CVn binary XY UMa

    NASA Astrophysics Data System (ADS)

    Gong, Hang; Osten, Rachel; Maccarone, Thomas; Reale, Fabio; Liu, Ji-Feng; Heckert, Paul A.

    2016-08-01

    We report on an archival X-ray observation of the eclipsing RS CVn binary XY UMa (P orb ≈ 0.48 d). In two Chandra ACIS observations spanning 200 ks and almost five orbital periods, three flares occurred. We find no evidence for eclipses in the X-ray flux. The flares took place around times of primary eclipse, with one flare occurring shortly (< 0.125 P orb) after a primary eclipse, and the other two happening shortly (< 0.05 P orb) before a primary eclipse. Two flares occurred within roughly one orbital period (Δα ≈ 1.024 P orb) of each other. We analyze the light curve and spectra of the system, and investigate coronal length scales during both quiescence and flares, as well as the timing of the flares. We explore the possibility that the flares are orbit-induced by introducing a small orbital eccentricity, which is quite challenging for this close binary.

  5. 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. (9 data files).

  6. CSS 41177: an eclipsing double white dwarf binary

    NASA Astrophysics Data System (ADS)

    Bours, Madelon

    2013-10-01

    The overwhelming majority of stellar remnants are white dwarfs. Despite their abundance and importance to, amongst others, Galactic age determinations and our understanding of type Ia supernovae fewer than a dozen white dwarfs have model-independent measurements of fundamental parameters like mass and radius. A major limitation on the observational side is that such parameters are extremely difficult to determine in a model-independant way for single white dwarfs. Close white dwarf binaries can provide these important tests.The largest class of white dwarf binaries in the Galaxy are the detached double white dwarfs, which are becoming increasingly popular as the progenitor systems of Type Ia supernovae. In recent years four eclipsing double white dwarfs have been found, creating the opportunity for precision mass and radius measurements of two white dwarfs at once. Our target, CSS 41177, contains two extremely low-gravity white dwarfs with very different temperatures, presenting us with a unique chance to test the existing mass-radius relation at its extremes.Here we propose a 2 orbit HST/COS FUV observation of CSS 41177, to accurately determine the temperature and surface gravity of the hot white dwarf. Through the flux ratio from the light curve this will at the same time constrain those of the cool white dwarf. Therefore it will allow us to add two more white dwarfs with accurate parameters to the short list of white dwarfs for which precise masses and radii are known.Note: The proposed observations are part of the doctoral thesis of Ms. Madelon C.P. Bours.

  7. OGLE II Eclipsing Binaries In The LMC: Analysis With Class

    NASA Astrophysics Data System (ADS)

    Devinney, Edward J.; Prsa, A.; Guinan, E. F.; DeGeorge, M.

    2011-01-01

    The Eclipsing Binaries (EBs) via Artificial Intelligence (EBAI) Project is applying machine learning techniques to elucidate the nature of EBs. Previously, Prsa, et al. applied artificial neural networks (ANNs) trained on physically-realistic Wilson-Devinney models to solve the light curves of the 1882 detached EBs in the LMC discovered by the OGLE II Project (Wyrzykowski, et al.) fully automatically, bypassing the need for manually-derived starting solutions. A curious result is the non-monotonic distribution of the temperature ratio parameter T2/T1, featuring a subsidiary peak noted previously by Mazeh, et al. in an independent analysis using the EBOP EB solution code (Tamuz, et al.). To explore this and to gain a fuller understanding of the multivariate EBAI LMC observational plus solutions data, we have employed automatic clustering and advanced visualization (CAV) techniques. Clustering the OGLE II data aggregates objects that are similar with respect to many parameter dimensions. Measures of similarity for example, could include the multidimensional Euclidean Distance between data objects, although other measures may be appropriate. Applying clustering, we find good evidence that the T2/T1 subsidiary peak is due to evolved binaries, in support of Mazeh et al.'s speculation. Further, clustering suggests that the LMC detached EBs occupying the main sequence region belong to two distinct classes. Also identified as a separate cluster in the multivariate data are stars having a Period-I band relation. Derekas et al. had previously found a Period-K band relation for LMC EBs discovered by the MACHO Project (Alcock, et al.). We suggest such CAV techniques will prove increasingly useful for understanding the large, multivariate datasets increasingly being produced in astronomy. We are grateful for the support of this research from NSF/RUI Grant AST-05-75042 f.

  8. The MACHO Project LMC variable star inventory. V. Classification and orbits of 611 eclipsing binary stars

    SciTech Connect

    The MACHO Collaboration

    1997-07-01

    We report the characteristics of 611 eclipsing binary stars in the Large Megallanic Cloud found by using the MACHO Project photometry database. The sample is magnitude limited, and extends down the main sequence to about spectral type A0. Many evolved binaries are also included. Each eclipsing binary is classified according to the traditional scheme of the {ital General Catalogue of Variable Stars} (EA and EB), and also according to a new decimal classification scheme defined in this paper. The new scheme is sensitive to the two major sources of variance in eclipsing binary star light curves{emdash}the sum of radii, and the surface-brightness ratio, and allow greater precision in characterizing the light curves. Examples of each type of light curve and their variations are given. Sixty-four of the eclipsing binaries have eccentric, rather than circular, orbits. The ephemeris and principal photometric characteristics of each eclipsing binary are listed in a table. Photometric orbits based on the Nelson{endash}Davis{endash}Etzel model have been fitted to all light curves. These data will be useful for planning future observations of these binaries. Plots of all data and fitted orbits and a table of the fitted orbital parameters are available on the AAS CD-ROM series, Vol. 9, 1997. These data are also available at the MACHO home page (http://wwwmacho.mcmaster.ca/). {copyright} {ital 1997 American Astronomical Society.}

  9. K2 Discovery of Young Eclipsing Binaries in Upper Scorpius: Direct Mass and Radius Determinations for the Lowest Mass Stars and Initial Characterization of an Eclipsing Brown Dwarf Binary

    NASA Astrophysics Data System (ADS)

    David, Trevor J.; Hillenbrand, Lynne A.; Cody, Ann Marie; Carpenter, John M.; Howard, Andrew W.

    2016-01-01

    We report the discovery of three low-mass double-lined eclipsing binaries in the pre-main sequence Upper Scorpius association, revealed by K2 photometric monitoring of the region over ˜78 days. The orbital periods of all three systems are <5 days. We use the K2 photometry plus multiple Keck/HIRES radial velocities (RVs) and spectroscopic flux ratios to determine fundamental stellar parameters for both the primary and secondary components of each system, along with the orbital parameters. We present tentative evidence that EPIC 203868608 is a hierarchical triple system comprised of an eclipsing pair of ˜25 MJup brown dwarfs with a wide M-type companion. If confirmed, it would constitute only the second double-lined eclipsing brown dwarf binary system discovered to date. The double-lined system EPIC 203710387 is composed of nearly identical M4.5-M5 stars with fundamentally determined masses and radii measured to better than 3% precision ({M}1=0.1183+/- 0.0028{M}⊙ , {M}2=0.1076+/- 0.0031{M}⊙ and {R}1=0.417+/- 0.010{R}⊙ , {R}2=0.450+/- 0.012{R}⊙ ) from combination of the light curve and RV time series. These stars have the lowest masses of any stellar mass double-lined eclipsing binary to date. Comparing our derived stellar parameters with evolutionary models, we suggest an age of ˜10-11 Myr for this system, in contrast to the canonical age of 3-5 Myr for the association. Finally, EPIC 203476597 is a compact single-lined system with a G8-K0 primary and a likely mid-K secondary whose lines are revealed in spectral ratios. Continued measurement of RVs and spectroscopic flux ratios will better constrain fundamental parameters and should elevate the objects to benchmark status. We also present revised parameters for the double-lined eclipsing binary UScoCTIO 5 ({M}1=0.3336+/- 0.0022{M}⊙ , {M}2=0.3200+/- 0.0022{M}⊙ and {R}1=0.862+/- 0.012, {R}2=0.852+/- 0.013{R}⊙ ), which are suggestive of a system age younger than previously reported. We discuss the

  10. Absolute properties of the eclipsing binary VV CORVI

    SciTech Connect

    Fekel, Francis C.; Henry, Gregory W.; Sowell, James R. E-mail: gregory.w.henry@gmail.com

    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 M {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.

  11. Photometry of 20 eclipsing and ellipsoidal binary systems

    NASA Astrophysics Data System (ADS)

    Shobbrook, R. R.

    2004-12-01

    A total of almost 2000 V observations of 20 eclipsing and ellipsoidal bright binary stars was collected between 1991 and 2001 for the purpose of determining more recent epoch ephemerides for the light curves than are available in the literature. The original purpose was to provide the Sydney University Stellar Interferometer (SUSI) with orbital periods and particularly the accurate times of minimum separation (light curve minima), so that the SUSI observations need not be used to determine them. This paper provides the periods, the times of primary minima and the phases of secondary minima for the 20 stars at an epoch as near as possible to the year 2000. No attempt has been made in this report to determine other parameters such as {apsidal motion} or stellar radii. Since the program was started in 1991, data for these stars taken in the period from late 1989 to early 1993 has also been available from the Hipparcos satellite; the light curves shown here include both sets of observations.

  12. Photometry of 20 eclipsing and ellipsoidal binary systems

    NASA Astrophysics Data System (ADS)

    Shobbrook, R. R.

    2005-12-01

    ERRATUM: In the published paper the phase diagrams of pi Sco and AL Scl were ommitted. The version reproduced in JAD11, 7 is the complete version. A total of almost 2000 V observations of 20 eclipsing and ellipsoidal bright binary stars was collected between 1991 and 2001 for the purpose of determining more recent epoch ephemerides for the light curves than are available in the literature. The original purpose was to provide the Sydney University Stellar Interferometer (SUSI) with orbital periods and particularly the accurate times of minimum separation (light curve minima), so that the SUSI observations need not be used to determine them. This paper provides the periods, the times of primary minima and the phases of secondary minima for the 20 stars at an epoch as near as possible to the year 2000. No attempt has been made in this report to determine other parameters such as {apsidal motion} or stellar radii. Since the program was started in 1991, data for these stars taken in the period from late 1989 to early 1993 has also been available from the Hipparcos satellite; the light curves shown here include both sets of observations.

  13. Doppler Imaging with FUSE: The Partially Eclipsing Binary VW Cep

    NASA Technical Reports Server (NTRS)

    Sonneborn, George (Technical Monitor); Brickhouse, Nancy

    2003-01-01

    This report covers the FUSE Guest Observer program. This project involves the study of emission line profiles for the partially eclipsing, rapidly rotating binary system VW Cep. Active regions on the surface of the star(s) produce observable line shifts as the stars move with respect to the observer. By studying the time-dependence of the line profile changes and centroid shifts, one can determine the location of the activity. FUSE spectra were obtained by the P.I. 27 Sept 2002 and data reduction is in progress. Since we are interested in line profile analysis, we are now investigating the wavelength scale calibration in some detail. We have also obtained and are analyzing Chandra data in order to compare the X-ray velocities with the FUV velocities. A complementary project comparing X-ray and Far UltraViolet (FUV) emission for the similar system 44i Boo is also underway. Postdoctoral fellow Ronnie Hoogerwerf has joined the investigation team and will perform the data analysis, once the calibration is optimized.

  14. Absolute properties of the eclipsing binary star V501 Herculis

    SciTech Connect

    Lacy, Claud H. Sandberg; Fekel, Francis C. E-mail: fekel@evans.tsuniv.edu

    2014-10-01

    V501 Her is a well detached G3 eclipsing binary star with a period of 8.597687 days for which we have determined very accurate light and radial-velocity curves using robotic telescopes. Results of these data indicate that the component stars have masses of 1.269 ± 0.004 and 1.211 ± 0.003 solar masses, radii of 2.001 ± 0.003 and 1.511 ± 0.003 solar radii, and temperatures of 5683 ± 100 K and 5720 ± 100 K, respectively. Comparison with the Yonsei-Yale series of evolutionary models results in good agreement at an age of about 5.1 Gyr for a somewhat metal-rich composition. Those models indicate that the more massive, larger, slightly cooler star is just beyond core hydrogen exhaustion while the less massive, smaller, slightly hotter star has not quite reached core hydrogen exhaustion. The orbit is not yet circularized, and the components are rotating at or near their pseudosynchronous velocities. The distance to the system is 420 ± 30 pc.

  15. The Distance to the Large Magellanic Cloud from Eclipsing Binaries

    NASA Astrophysics Data System (ADS)

    Fitzpatrick, E. L.; Ribas, I.; Guinan, E. F.; DeWarf, L. E.; Maloney, F. P.; Massa, D. L.

    2000-05-01

    We have determined the distance to a second eclipsing binary system (EB) in the Large Magellanic Cloud, HV982 (B1 IV-V + B1 IV-V). The measurement of the distance - among other properties of the system - is based on optical photometry and spectroscopy and space-based UV/optical spectrophotometry. The analysis combines the "classical" EB study of light and radial velocity curves, which yield the stellar masses and radii, with a new analysis of the observed energy distribution, which yields the effective temperature, metallicity, and reddening of the system, plus the distance ``attenuation factor,'' essentially (radius/distance)2. This distance determination is extremely robust. It consists of a detailed study of well-understood objects (B stars) in a well-understood evolutionary phase (core H burning), whose results are entirely consistent with stellar evolution calculations. There are no ``tuneable'' parameters. There are no ``zeropoint'' uncertainties. The analysis is insensitive to stellar metallicity, although the metallicity is explicitly determined and incorporated. The reddening of the system is also determined explicitly and incorporated in the analysis. Moreover, the results depend on no statistical averages and are susceptible to no sampling biases. In this poster we describe the analysis technique and present the new results for HV982. The results are consistent - to within the measurement errors - with those published earlier by us for the EB system HV2274 and offer a very strong argument in favor of the "short" LMC distance scale, corresponding to V0 - MV = 18.3.

  16. Absolute properties of the eclipsing binary star AP Andromedae

    SciTech Connect

    Sandberg Lacy, Claud H.; Torres, Guillermo; Fekel, Francis C.; Muterspaugh, Matthew W. E-mail: gtorres@cfa.harvard.edu E-mail: matthew1@coe.tsuniv.edu

    2014-06-01

    AP And is a well-detached F5 eclipsing binary star for which only a very limited amount of information was available before this publication. We have obtained very extensive measurements of the light curve (19,097 differential V magnitude observations) and a radial velocity curve (83 spectroscopic observations) which allow us to fit orbits and determine the absolute properties of the components very accurately: masses of 1.277 ± 0.004 and 1.251 ± 0.004 M {sub ☉}, radii of 1.233 ± 0.006 and 1.1953 ± 0.005 R {sub ☉}, and temperatures of 6565 ± 150 K and 6495 ± 150 K. The distance to the system is about 400 ± 30 pc. Comparison with the theoretical properties of the stellar evolutionary models of the Yonsei-Yale series of Yi et al. shows good agreement between the observations and the theory at an age of about 500 Myr and a slightly sub-solar metallicity.

  17. A 12 MINUTE ORBITAL PERIOD DETACHED WHITE DWARF ECLIPSING BINARY

    SciTech Connect

    Brown, Warren R.; Kilic, Mukremin; Kenyon, Scott J.; Hermes, J. J.; Winget, D. E.; Prieto, Carlos Allende E-mail: mkilic@cfa.harvard.edu E-mail: jjhermes@astro.as.utexas.edu E-mail: callende@iac.es

    2011-08-10

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

  18. ABSOLUTE PROPERTIES OF THE ECLIPSING BINARY STAR BF DRACONIS

    SciTech Connect

    Sandberg Lacy, Claud H.; Torres, Guillermo; Fekel, Francis C.; Sabby, Jeffrey A.; Claret, Antonio E-mail: gtorres@cfa.harvard.edu E-mail: jsabby@siue.edu

    2012-06-15

    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 coude-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 H{sub p}. We find, however, that standard tidal theory is unable to match the observed slow rotation rates of the components' surface layers.

  19. PSR J1723–2837: AN ECLIPSING BINARY RADIO MILLISECOND PULSAR

    SciTech Connect

    Crawford, Fronefield; Lyne, Andrew G.; Stairs, Ingrid H.; Kaplan, David L.; McLaughlin, Maura A.; Lorimer, Duncan R.; Freire, Paulo C. C.; Kramer, Michael; Burgay, Marta; D'Amico, Nichi; Possenti, Andrea; Camilo, Fernando; Faulkner, Andrew; Manchester, Richard N.; Steeghs, Danny

    2013-10-10

    We present a study of PSR J1723–2837, an eclipsing, 1.86 ms millisecond binary radio pulsar discovered in the Parkes Multibeam survey. Radio timing indicates that the pulsar has a circular orbit with a 15 hr orbital period, a low-mass companion, and a measurable orbital period derivative. The eclipse fraction of ∼15% during the pulsar's orbit is twice the Roche lobe size inferred for the companion. The timing behavior is significantly affected by unmodeled systematics of astrophysical origin, and higher-order orbital period derivatives are needed in the timing solution to account for these variations. We have identified the pulsar's (non-degenerate) companion using archival ultraviolet, optical, and infrared survey data and new optical photometry. Doppler shifts from optical spectroscopy confirm the star's association with the pulsar and indicate a pulsar-to-companion mass ratio of 3.3 ± 0.5, corresponding to a companion mass range of 0.4 to 0.7 M{sub ☉} and an orbital inclination angle range of between 30° and 41°, assuming a pulsar mass range of 1.4-2.0 M{sub ☉}. Spectroscopy indicates a spectral type of G for the companion and an inferred Roche-lobe-filling distance that is consistent with the distance estimated from radio dispersion. The features of PSR J1723–2837 indicate that it is likely a 'redback' system. Unlike the five other Galactic redbacks discovered to date, PSR J1723–2837 has not been detected as a γ-ray source with Fermi. This may be due to an intrinsic spin-down luminosity that is much smaller than the measured value if the unmeasured contribution from proper motion is large.

  20. Secondary Eclipse Observations of the Low-Mass Hot-Jupiter WASP-11b/HAT-P-10b

    NASA Astrophysics Data System (ADS)

    Bowman, M. Oliver; Harrington, J.; Blecic, J.; Foster, A.; Stevenson, K. B.; Cubillos, P.; Collier Cameron, A.; UCF Exoplanets Group

    2013-10-01

    WASP-11b/HAT-P-10b is a hot-Jupiter planet that orbits a K3 dwarf every 3.722 days at a distance of 0.0439 AU. Using the Spitzer Space Telescope in 2009 (Harrington, P.I.) and 2010 (Knutson, P.I), we observed five secondary eclipses of WASP-11b/HAT-P-10b: two in the 3.6-micron channel, two in the 4.5-micron channel, and one in the 8-micron channel. We present eclipse-depth measurements, estimates of infrared brightness temperatures, and the first constraints on the atmospheric pressure and temperature profile and chemical compositions. We also refine its orbit using our own secondary-eclipse measurements in combination with external radial-velocity and transit observations from both professional and amateur observers. Spitzer is operated by the Jet Propulsion Laboratory, California Institute of Technology, under a contract with NASA. This work was supported in part by NASA Planetary Atmospheres grant NNX13AF38G.

  1. Time-Dependent Behavior of the O'Connell Effect in Eclipsing Binary Star Systems

    NASA Astrophysics Data System (ADS)

    Beaky, Matthew M.; Koju, V.

    2012-05-01

    The characteristic shape of an eclipsing binary light curve consists of two out-of-eclipse maxima and two mid-eclipse minima. Many eclipsing binary light curves exhibit unequally high maxima, a feature known as the O'Connell effect. So far, this asymmetry has not been convincingly explained aside from a few individual systems. Most theories attribute the O'Connell effect to phenomena such as starspots, clouds of circumstellar gas and dust, or a hot spot caused by the impact of a mass-transferring gas stream. The high precision and nearly continuous temporal coverage of light curves produced by the Kepler Space Mission make it possible to detect variations in the O'Connell effect within individual systems that have not previously been observed via ground-based observations. Our analysis of Kepler light curves of eclipsing binary systems reveals that in most cases the size and even the sign of the O'Connell effect changes significantly over time scales of weeks or months. Moreover, the magnitude difference between the eclipse minima also varies, usually lagging behind the variations in the difference between the out-of-eclipse maxima by several orbital cycles. We have created models of eclipsing binary systems using Binary Maker 3 that include starspots that migrate slowly in longitude, and have analyze the light curves generated by these model systems. Models with constant starspots at fixed latitude and models with starspots that vary in size and latitude both reproduce the qualitative behavior of the time-dependent O'Connell effect in the Kepler light curves very closely. These results provide support for the notion that the O'Connell effect, at least in some cases, is caused by migrating starspots on the surface of one or both components of the binary star system.

  2. Discovery of two young brown dwarfs in an eclipsing binary system.

    PubMed

    Stassun, Keivan G; Mathieu, Robert D; Valenti, Jeff A

    2006-03-16

    Brown dwarfs are considered to be 'failed stars' in the sense that they are born with masses between the least massive stars (0.072 solar masses, M(o)) and the most massive planets (approximately 0.013M(o)); they therefore serve as a critical link in our understanding of the formation of both stars and planets. Even the most fundamental physical properties of brown dwarfs remain, however, largely unconstrained by direct measurement. Here we report the discovery of a brown-dwarf eclipsing binary system, in the Orion Nebula star-forming region, from which we obtain direct measurements of mass and radius for these newly formed brown dwarfs. Our mass measurements establish both objects as brown dwarfs, with masses of 0.054 +/- 0.005M(o) and 0.034 +/- 0.003M(o). At the same time, with radii relative to the Sun's of 0.669 +/- 0.034R(o) and 0.511 +/- 0.026R(o), these brown dwarfs are more akin to low-mass stars in size. Such large radii are generally consistent with theoretical predictions for young brown dwarfs in the earliest stages of gravitational contraction. Surprisingly, however, we find that the less-massive brown dwarf is the hotter of the pair; this result is contrary to the predictions of all current theoretical models of coeval brown dwarfs. PMID:16541067

  3. Period and light-curve study of the contact eclipsing binary V523 Cas

    NASA Astrophysics Data System (ADS)

    Mohammadi, Mahya; Abedi, Abbas; Riazi, Nematollah

    2016-04-01

    CCD photometry of the eclipsing W Uma binary system V523 Cas in U, B, V and RC filters was carried out during eight nights in 2012. The physical and geometrical parameters of this system are obtained. A possible pulsation period of one of the components is obtained by analyzing the residuals of the ephemeris light curve. Our observations contain 16 times of minimum light. We combined these with all available published times of minimum. By fitting a quadratic curve to the O-C values, a new ephemeris of the system is calculated. By attributing the period change to mass transfer, we find a mass transfer rate of 4 ×10-12 M⊙/yr. Also, Period (80.58 yr) and the minimum mass (0.3 M⊙) of a possible third body is estimated. In addition, the possible existence of a fourth body with a mass of order 0.15 M⊙ is discussed. These third and fourth bodies could be low-mass main-sequence stars (red dwarfs).

  4. Dust Scattering Halo from an Eclipsing X-ray Binary at 1.5 arcmin from Sgr A*

    NASA Astrophysics Data System (ADS)

    Jin, Chichuan; Haberl, Frank; Ponti, Gabriele

    2016-07-01

    AX J1745.6-2901 is an eclipsing neutron star low mass X-ray binary. This source is bright in X-rays and it has a high column density of absorbing gas along the line of sight, showcasing a strong dust scattering halo. Moreover, the dust scattering halo shows time evolution during the eclipsing phase. The combination of these phenomena can provide important information about the location of the neutron star and the dust properties along the line of sight. In this talk, I will show that based on a large set of XMM-Newton and Chandra data, we can conduct, for the first time, a powerful combined analysis of the radial profile of the dust scattering halo and the time evolution of the halo during the eclipsing phase. Our study can put constraints on the location of the source, the distribution and composition of the dust, and the metal abundance towards the source. Due to the proximity of the source to Sgr A* (only 1.5 arcmin), these properties are highly relevant to the dust in the Galactic centre, and are likely to be similar as the dust properties on the line of sight towards Sgr A*.

  5. Introducing Adapted Nelder & Mead's Downhill Simplex Method to a Fully Automated Analysis of Eclipsing Binaries

    NASA Astrophysics Data System (ADS)

    Prsa, A.; Zwitter, T.

    2005-01-01

    Eclipsing binaries are extremely attractive objects because absolute physical parameters (masses, luminosities, radii) of both components may be determined from observations. Since most efforts to extract these parameters were based on dedicated observing programmes, existing modelling code is based on interactivity. Gaia will make a revolutionary advance in shear number of observed eclipsing binaries and new methods for automatic handling must be introduced and thoroughly tested. This paper focuses on Nelder & Mead's downhill simplex method applied to a synthetically created test binary as it will be observed by Gaia.

  6. Eclipsing Binary Stars in the OGLE-III Fields of the Small Magellanic Cloud

    NASA Astrophysics Data System (ADS)

    Pawlak, M.; Graczyk, D.; Soszyński, I.; Pietrukowicz, P.; Poleski, R.; Udalski, A.; Szymański, M. K.; Kubiak, M.; Pietrzyński, G.; Wyrzykowski, Ł.; Ulaczyk, K.; Kozłowski, S.; Skowron, J.

    2013-09-01

    We present a large sample of eclipsing binary stars detected in the Small Magellanic Cloud fields covering about 14 square degrees that have been monitored for eight years during the third phase of the OGLE survey. This is the largest set of such variables containing 6138 objects, of which 777 are contact and 5361 non-contact binaries. The estimated completeness of this sample is around 82%. We analyze the statistical properties of the sample and present selected interesting objects: 32 systems having eccentric orbit with visible apsidal motion, one Transient Eclipsing Binary, ten RS CVn type stars, 22 still unexplained Double-Periodic Variable stars, and 15 candidates for doubly eclipsing quadruple systems. Based on the OGLE-III proper motions, we classified 47 binaries from our sample as foreground Galactic stars. We also list candidates suitable for the SMC distance determination.

  7. Constraining the formation of black holes in short-period black hole low-mass X-ray binaries

    NASA Astrophysics Data System (ADS)

    Repetto, Serena; Nelemans, Gijs

    2015-11-01

    The formation of stellar-mass black holes (BHs) is still very uncertain. Two main uncertainties are the amount of mass ejected in the supernova (SN) event (if any) and the magnitude of the natal kick (NK) the BH receives at birth (if any). Repetto et al., studying the position of Galactic X-ray binaries containing BHs, found evidence for BHs receiving high NKs at birth. In this paper, we extend that study, taking into account the previous binary evolution of the sources as well. The seven short-period BH X-ray binaries that we use are compact binaries consisting of a low-mass star orbiting a BH in a period less than 1 d. We trace their binary evolution backwards in time, from the current observed state of mass transfer, to the moment the BH was formed, and we add the extra information on the kinematics of the binaries. We find that several systems could be explained by no NK, just mass ejection, while for two systems (and possibly more) a high kick is required. So unless the latter have an alternative formation, such as within a globular cluster, we conclude that at least some BHs get high kicks. This challenges the standard picture that BH kicks would be scaled down from neutron star kicks. Furthermore, we find that five systems could have formed with a non-zero NK but zero mass ejected (i.e. no SN) at formation, as predicted by neutrino-driven NKs.

  8. APSIDAL MOTION OF THE ECLIPSING BINARY AS CAMELOPARDALIS: DISCREPANCY RESOLVED

    SciTech Connect

    Pavlovski, K.; Kolbas, V.; Southworth, J.

    2011-06-20

    We present a spectroscopic study of the eclipsing binary system AS Camelopardalis, the first such study based on phase-resolved CCD echelle spectra. Via a spectral disentangling analysis we measure the minimum masses of the stars to be M{sub A}sin {sup 3} i = 3.213 {+-} 0.032 M{sub sun} and M{sub B}sin {sup 3} i = 2.323 {+-} 0.032 M{sub sun}, their effective temperatures to be T{sub eff}(A) = 12, 840 {+-} 120 K and T{sub eff}(B) = 10, 580 {+-} 240 K, and their projected rotational velocities to be v{sub A}sin i{sub A} = 14.5 {+-} 0.1 km s{sup -1} and v{sub B}sin i{sub B} {<=} 4.6 {+-} 0.1 km s{sup -1}. These projected rotational velocities appear to be much lower than the synchronous values. We show that measurements of the apsidal motion of the system suffer from a degeneracy between orbital eccentricity and apsidal motion rate. We use our spectroscopically measured e = 0.164 {+-} 0.004 to break this degeneracy and measure {omega}-dot{sub obs} = 0{sup 0}.133{+-}0{sup 0}.010 yr{sup -1}. Subtracting the relativistic contribution of {omega}-dot{sub GR} = 0{sup 0}.0963{+-}0{sup 0}0002 yr{sup -1} yields the contribution due to tidal torques: {omega}-dot{sub cl} = 0{sup 0}.037{+-}0{sup 0}.010 yr{sup -1}. This value is much smaller than the rate predicted by stellar theory, 0.{sup 0}40-0.{sup 0}87 yr{sup -1}. We interpret this as a misalignment between the orbital axis of the close binary and the rotational axes of its component stars, which also explains their apparently low rotational velocities. The observed and predicted apsidal motion rates could be brought into agreement if the stars were rotating three times faster than synchronous about axes perpendicular to the orbital axis. Measurement of the Rossiter-McLaughlin effect can be used to confirm this interpretation.

  9. Studying populations of eclipsing binaries using large scale multi-epoch photometric surveys

    NASA Astrophysics Data System (ADS)

    Mowlavi, Nami; Barblan, Fabio; Holl, Berry; Rimoldini, Lorenzo; Lecoeur-Taïbi, Isabelle; Süveges, Maria; Eyer, Laurent; Guy, Leanne; Nienartowicz, Krzysztof; Ordonez, Diego; Charnas, Jonathan; Jévardat de Fombelle, Grégory

    2015-08-01

    Large scale multi-epoch photometric surveys provide unique opportunities to study populations of binary stars through the study of eclipsing binaries, provided the basic properties of binary systems can be derived from their light curves without the need to fully model the binary system. Those systems can then be classified into various types from, for example, close to wide systems, from circular to highly elliptical systems, or from systems with similar components to highly asymmetric systems. The challenge is to extract physically relevant information from the light curve geometry.In this contribution, we present the study of eclipsing binaries in the Large Magellanic Clouds (LMC) from the OGLE-III survey. The study is based on the analysis of the geometry of their light curves parameterized using a two-Gaussian model. We show what physical parameters could be extracted from such an analysis, and the results for the LMC eclipsing binaries. The method is very well adapted to process large-scale surveys containing millions of eclipsing binaries, such as is expected from the current Gaia mission or the future LSST survey.

  10. Kepler Eclipsing Binary Stars. Scientific Harvest from the First 4 Months of Data

    NASA Astrophysics Data System (ADS)

    Prsa, Andrej; Orosz, J. A.; Welsh, W. F.; Slawson, R. W.; Batalha, N.; Rucker, M.; Doyle, L. R.

    2011-05-01

    The Kepler mission observed over 2200 eclipsing binary stars in its 105-square degree field of view. Their importance in modern astrophysics cannot be overstated -- it ranges from deriving the fundamental stellar parameters across the Hertzsprung-Russell Diagram and calibrating the mass-radius-temperature relationships, to determining the distances in the Galaxy and beyond. Kepler observations provide a unique sample with a nearly continuous coverage and sub-millimag precision, allowing us to model binary star light curves to unprecedented accuracy. In the context of planet hunting, the period and amplitude statistics derived from this sample are used to estimate the occurence rate of false positives: stellar sources that mimic planet transits due to third light contamination. I will present the results of the studies performed by the Kepler Eclipsing Binary Working Group: 1) determining the physical parameters of binary star components, 2) studying the eclipse timing variations that attest to the presence of third bodies or arise due to component interaction, 3) performing statistical analysis of the whole sample, 4) estimating the occurence rate of background eclipsing binaries, and 5) searching for tertiary events due to other eclipsing objects. This work is supported by the NASA/SETI grant 08-SC-1041 and NSF RUI #AST-05-07542.

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

    SciTech Connect

    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 a 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.

  12. Time-series Spectroscopy of the Eclipsing Binary Y Cam with a Pulsating Component

    NASA Astrophysics Data System (ADS)

    Hong, Kyeongsoo; Lee, Jae Woo; Kim, Seung-Lee; Koo, Jae-Rim; Lee, Chung-Uk; Yushchenko, Alexander V.; Kang, Young-Woon

    2015-10-01

    We present the physical properties of the semi-detached Algol-type eclipsing binary Y Cam based on high resolution spectra obtained using the Bohyunsan Optical Echelle Spectrograph. This is the first spectroscopic monitoring data obtained for this interesting binary system, which has a δ Sct-type pulsating component. We obtained a total of 59 spectra over 14 nights from 2009 December to 2011 March. Double-lined spectral features from the hot primary and cool secondary components were well identified. We determined the effective temperatures of the two stars to be Teff,1 = 8000 ± 250 K and Teff,2 = 4629 ± 150 K. The projected rotational velocities are v1sin i1 = 51 ± 4 km s-1 and v2sin i2 = 50 ± 10 km s-1, which are very similar to a synchronous rotation with the orbital motion. Physical parameters of each component were derived by analyzing our radial velocity data together with previous photometric light curves from the literature. The masses and radii are M1 = 2.08 ± 0.09 M⊙, M2 = 0.48 ± 0.03 M⊙, R1 = 3.14 ± 0.05 R⊙, and R2 = 3.33 ± 0.05 R⊙, respectively. A comparison of these parameters with the theoretical evolution tracks showed that the primary component is located between the zero-age main sequence and the terminal-age main sequence, while the low-mass secondary is noticeably evolved. This indicates that the two components have experienced mass exchange with each other and the primary has undergone an evolution process different from that of single δ Sct-type pulsators.

  13. THE PHASES DIFFERENTIAL ASTROMETRY DATA ARCHIVE. II. UPDATED BINARY STAR ORBITS AND A LONG PERIOD ECLIPSING BINARY

    SciTech Connect

    Muterspaugh, Matthew W.; O'Connell, J.; Hartkopf, William I.; Lane, Benjamin F.; Williamson, M.; Kulkarni, S. R.; Konacki, Maciej; Burke, Bernard F.; Colavita, M. M.; Shao, M.; Wiktorowicz, Sloane J. E-mail: wih@usno.navy.mi E-mail: maciej@ncac.torun.p

    2010-12-15

    Differential astrometry measurements from the Palomar High-precision Astrometric Search for Exoplanet Systems have been combined with lower precision single-aperture measurements covering a much longer timespan (from eyepiece measurements, speckle interferometry, and adaptive optics) to determine improved visual orbits for 20 binary stars. In some cases, radial velocity observations exist to constrain the full three-dimensional orbit and determine component masses. The visual orbit of one of these binaries-{alpha} Com (HD 114378)-shows that the system is likely to have eclipses, despite its very long period of 26 years. The next eclipse is predicted to be within a week of 2015 January 24.

  14. A low-mass-ratio and deep contact binary as the progenitor of the merger V1309 Sco

    NASA Astrophysics Data System (ADS)

    Zhu, Li-Ying; Zhao, Er-Gang; Zhou, Xiao

    2016-04-01

    Nova Sco 2008 (=V1309 Sco) is an example of a V838 Mon type eruption rather than a typical classical nova. This enigmatic object was recently shown to have resulted from the merger of two stars in a contact binary. It is the first stellar merger that was identified to be undergoing a common envelope transient. To understand the properties of its binary progenitor, the pre-outburst light curves were analyzed by using the W-D method. The photometric solution of the 2002 light curve shows that it is a deep contact binary (f = 89.5(±40.5)%) with a mass ratio of 0.094. The asymmetry of the light curve is explained by the presence of a dark spot on the more massive component. The extremely high fill-out factor suggests that the merging of the contact binary is driven by dynamical mass loss from the outer Lagrange point. However, the analysis of the 2004 light curve indicates that no solutions were obtained even at an extremely low mass ratio of q = 0.03. This suggests that the common convective envelope of the binary system disappeared and the secondary component spiraled into the envelope of the primary in 2004. Finally, the ejection of the envelope of the primary produced the outburst.

  15. Searching for Pulsating Stars in Eclipsing Binaries in the OMC--VAR Catalogue

    NASA Astrophysics Data System (ADS)

    Alfonso-Garzón, J.; Moya, A.; Montesinos, B.; Mas-Hesse, J. M.; Domingo, A.

    The first catalogue of variable sources observed by OMC (OMC--VAR hereafter) contains light curves for 5263 variable stars, out of which we have been able to detect periodicities for 1137 objects. A large variety of objects can be found in the catalogue, but the most frequent ones in the present compilation are pulsating stars and eclipsing binaries. We have performed an analysis to find eclipsing systems showing evidences of pulsations in one of their components some preliminary results are shown.

  16. V907 Scorpii: A Remarkable Binary Star Whose Eclipses Turn On and Off and On and Off

    NASA Astrophysics Data System (ADS)

    Lacy, Claud H. Sandberg; Helt, Bodil E.; Vaz, Luiz Paulo R.

    1999-01-01

    V907 Scorpii, near the open cluster M7, and possibly a member, is unique among all known eclipsing binary stars because its eclipses have turned on and off twice within modern history. By using all available photometric and spectroscopic data, we have discovered that it is at least a triple star and possibly a quadruple star system consisting of a visual binary with a very long orbital period, the brighter member of which is itself the triple star. The triple star contains an eclipsing binary star (B9.5 V) with an orbital period of 3.78 days and a faint, distant companion (late K, or perhaps a white dwarf) with an orbital period of 99.3 days around the center of mass of the triple star system. Radial velocity measurements allow the masses to be estimated. Because the orbital planes of the eclipsing binary and its triple companion are not coplanar, the orbital plane of the eclipsing binary shows nodal regression with a period of 68 yr. For about one-third of this time, the close binary is eclipsing; the rest of the time the inclination is too small for eclipses to occur. The earliest observations of the system in the year 1899 show eclipses; the eclipses stopped about 1918, started again about 1963, and stopped again in about 1986. We predict that the eclipses should start occurring once again in the year 2030+/-5.

  17. Calibrating the updated overshoot mixing model on eclipsing binary stars: HY Vir, YZ Cas, χ{sup 2} Hya, and VV Crv

    SciTech Connect

    Meng, Y.; Zhang, Q. S.

    2014-06-01

    Detached eclipsing binary stars with convective cores provide a good tool to investigate convective core overshoot. It has been performed on some binary stars to restrict the classical overshoot model which simply extends the boundary of the fully mixed region. However, the classical overshoot model is physically unreasonable and inconsistent with helioseismic investigations. An updated model of overshoot mixing was established recently. There is a key parameter in the model. In this paper, we use observations of four eclipsing binary stars, i.e., HY Vir, YZ Cas, χ{sup 2} Hya, and VV Crv, to investigate a suitable value for the parameter. It is found that the value suggested by calibrations on eclipsing binary stars is the same as the value recommended by other methods. In addition, we have studied the effects of the updated overshoot model on the stellar structure. The diffusion coefficient of convective/overshoot mixing is very high in the convection zone, then quickly decreases near the convective boundary, and exponentially decreases in the overshoot region. The low value of the diffusion coefficient in the overshoot region leads to weak mixing and a partially mixed overshoot region. Semi-convection, which appears in the standard stellar models of low-mass stars with convective cores, is removed by partial overshoot mixing.

  18. Wide Low-Mass Tertiary Companions of Binary Star Systems as a Test of Star Formation Theories

    NASA Astrophysics Data System (ADS)

    Douglas, Stephanie; Allen, P.

    2012-01-01

    We will present the status of a common proper motion search for wide low-mass stellar and sub-stellar companions to known white dwarf-M dwarf binary systems. I-band observations were made using the 31" NURO telescope at Lowell Observatory. Candidate companions are selected using astrometry from our own data and 2MASS photometry. We have begun to spectroscopically confirm candidates that pass our selection criteria. The ultimate goal of the search is to test star formation theories which predict that close binary systems form by transferring angular momentum to a third companion. To this end, we will model the physical companion population and perform Bayesian statistical analysis to determine the best-fit population model to our data. Here we will present our spectroscopically confirmed companions as well as the preliminary results of our population models and statistical analysis.

  19. CHARACTERIZING LOW-MASS BINARIES FROM OBSERVATION OF LONG-TIMESCALE CAUSTIC-CROSSING GRAVITATIONAL MICROLENSING EVENTS

    SciTech Connect

    Shin, I.-G.; Han, C.; Choi, J.-Y.; Udalski, A.; Szymanski, M. K.; Kubiak, M.; Soszynski, I.; Pietrzynski, G.; Poleski, R.; Ulaczyk, K.; Pietrukowicz, P.; Kozlowski, S.; Wyrzykowski, L.; Sumi, T.; Gould, A.; Skowron, J.; Bozza, V.; Dominik, M.; Horne, K.; Fouque, P.; Collaboration: OGLE Collaboration; MOA Collaboration; RoboNet Collaboration; MiNDSTEp Consortium; muFUN Collaboration; PLANET Collaboration; and others

    2012-08-20

    Despite the astrophysical importance of binary star systems, detections are limited to those located in small ranges of separations, distances, and masses and thus it is necessary to use a variety of observational techniques for a complete view of stellar multiplicity across a broad range of physical parameters. In this paper, we report the detections and measurements of two binaries discovered from observations of microlensing events MOA-2011-BLG-090 and OGLE-2011-BLG-0417. Determinations of the binary masses are possible by simultaneously measuring the Einstein radius and the lens parallax. The measured masses of the binary components are 0.43 M{sub Sun} and 0.39 M{sub Sun} for MOA-2011-BLG-090 and 0.57 M{sub Sun} and 0.17 M{sub Sun} for OGLE-2011-BLG-0417 and thus both lens components of MOA-2011-BLG-090 and one component of OGLE-2011-BLG-0417 are M dwarfs, demonstrating the usefulness of microlensing in detecting binaries composed of low-mass components. From modeling of the light curves considering full Keplerian motion of the lens, we also measure the orbital parameters of the binaries. The blended light of OGLE-2011-BLG-0417 comes very likely from the lens itself, making it possible to check the microlensing orbital solution by follow-up radial-velocity observation. For both events, the caustic-crossing parts of the light curves, which are critical for determining the physical lens parameters, were resolved by high-cadence survey observations and thus it is expected that the number of microlensing binaries with measured physical parameters will increase in the future.

  20. MOST satellite photometry of stars in the M67 field: eclipsing binaries, blue stragglers and δ Scuti variables

    NASA Astrophysics Data System (ADS)

    Pribulla, Theodor; Rucinski, Slavek; Matthews, Jaymie M.; Kallinger, Thomas; Kuschnig, Rainer; Rowe, Jason F.; Guenther, David B.; Moffat, Anthony F. J.; Sasselov, Dimitar; Walker, Gordon A. H.; Weiss, Werner W.

    2008-11-01

    We present two series of MOST (Microvariability and Oscillations of STars) space-based photometry, covering nearly continuously 10 d in 2004 and 30 d in 2007, of selected variable stars in the upper main sequence of the old open cluster M67. New high-precision light curves were obtained for the blue straggler binary/triple systems AH Cnc, ES Cnc and EV Cnc. The precision and phase coverage of ES Cnc and EV Cnc is by far superior to any previous observations. The light curve of ES Cnc is modelled in detail, assuming two dark photospheric spots and Roche geometry. An analysis of the light curve of AH Cnc indicates a low mass ratio (q ~ 0.13) and a high inclination angle for this system. Two new long-period eclipsing binaries, GSC 814-323 and HD 75638 (non-members of M67) were discovered. We also present ground-based DDO spectroscopy of ES Cnc and of the newly found eclipsing binaries. Especially interesting is HD 75638, a member of a visual binary, which must itself be a triple or a higher multiplicity system. New light curves of two δ Scuti pulsators, EX Cnc and EW Cnc, have been analysed leading to detection of 26 and eight pulsation frequencies of high temporal stability. Based on photometric data from MOST, a Canadian Space Agency mission (jointly operated by Dynacon Inc., the University of Toronto Institute for Aerospace Studies and the University of British Columbia, with the assistance of the University of Vienna), and on spectroscopic data from the David Dunlap Observatory, University of Toronto. E-mail: pribulla@ta3.sk (TP); rucinski@astro.utoronto.ca (SR)

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

    SciTech Connect

    Jetsu, L.; Porceddu, S.; Lyytinen, J.; Kajatkari, P.; Lehtinen, J.; Markkanen, T.; Toivari-Viitala, J.

    2013-08-10

    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 Cairo 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.

  2. Did the Ancient Egyptians Record the Period of the Eclipsing Binary Algol—The Raging One?

    NASA Astrophysics Data System (ADS)

    Jetsu, L.; Porceddu, S.; Lyytinen, J.; Kajatkari, P.; Lehtinen, J.; Markkanen, T.; Toivari-Viitala, J.

    2013-08-01

    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 Cairo 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.

  3. 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.

  4. The distance to the Andromeda galaxy from eclipsing binaries

    NASA Astrophysics Data System (ADS)

    Vilardell, F.; Ribas, I.; Jordi, C.; Fitzpatrick, E. L.; Guinan, E. F.

    2010-01-01

    The cosmic distance scale largely depends on distance determinations to galaxies of the Local Group. In this sense, the Andromeda galaxy (M 31) is a key rung to better constrain the cosmic distance ladder. A project was started in 1999 to firmly establish a direct and accurate distance to M 31 using eclipsing binaries (EBs). After the determination of the first direct distance to M 31 from EBs, the second direct distance to an EB system is presented: M31V J00443610+4129194. Light and radial velocity curves were obtained and fitted to derive the masses and radii of the components. The acquired spectra were combined and disentangled to determine the temperature of the components. The analysis of the studied EB resulted in a distance determination to M 31 of (m-M)0 = 24.30 ± 0.11 mag. This result, when combined with the previous distance determination to M 31, results in a distance modulus of (m-M)0 = 24.36 ± 0.08 mag (744 ± 33 kpc), fully compatible with other distance determinations to M 31. With an error of only 4%, the obtained value firmly establishes the distance to this important galaxy and represents the fulfillment of the main goal of our project. Based on observations made with the Isaac Newton Telescope operated on the island of La Palma by the Isaac Newton Group in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofísica de Canarias.Based on observations obtained at the Gemini Observatory, which is operated by the Association of Universities for Research in Astronomy, Inc., under a cooperative agreement with the NSF on behalf of the Gemini partnership: the National Science Foundation (United States), the Science and Technology Facilities Council (United Kingdom), the National Research Council (Canada), CONICYT (Chile), the Australian Research Council (Australia), Ministério da Ciência e Tecnologia (Brazil) and Ministerio de Ciencia, Tecnología e Innovación Productiva (Argentina)Original data are only available in

  5. Photometric Observations of the Totally Eclipsing, Solar Type Eclipsing Binary, DK Andromedae

    NASA Astrophysics Data System (ADS)

    Samec, Ronald G.; Faulkner, D. R.; Van Hamme, W. V.; Kring, J.

    2013-06-01

    We present the first precision BVRI light curves, synthetic light curve solutions and a period study for the Sonneberg variable, DK And. Observations were taken with the NURO 0.81-m Lowell reflector on 24, 25 and 27 September and 26 October and 01 November 2011 with the SARA 0.9-m reflector. Our light curves were premodeled with Binary Maker 3.0, and solved with the Wilson-Devinney program. Our observations included 374 B, 372 V, 392 R and 394 I individual and calibrated observations. These were taken with the NURO, Lowell 2KX2K NASACAM, and the SARA 1KX1K Apogee camera. Six mean times of minimum light were determined, includingHJDMin I= 2455866.8222(±0.0003), 2455828.6632(±0.0001), 2455829.6405(±0.0097), and HJDMin II=2455866.5782(±0.0007), 2455860.6970(±0.0053) and 2455828.9081(±0.0004). Thirty-one timings taken over 73 years are included in our ephemeris calculation: J.D. Hel Min I = 2451435.4330(±0.0011)d + 0.48922346(±0.00000015)×E + 2.4(±0.4)×10-11×E2 For conservative mass transfer, the positive quadratic term means that the more massive star is the gainer. Our light curves shows a time of constant light in the secondary eclipse of 28 minutes making this an A-type W UMa system. The amplitude of the light curves are about 0.5 mags in V. The light curve solution reveals a rather extreme mass ratio of 0.32, a component temperature difference of ~300K, and an inclination of 82.5°. The curves show the effects of dark spot activity. We thank USC, Lancaster for their support of our membership in NURO for the past 8 years, the American Astronomical Society for its support through its small research program and Arizona Space grant for the partial support for our student’s travel.

  6. Variable Doppler shifts of the thermal wind absorption lines in low-mass X-ray binaries

    NASA Astrophysics Data System (ADS)

    Madej, O. K.; Jonker, P. G.; Díaz Trigo, M.; Miškovičová, I.

    2014-02-01

    In this paper, we address the general applicability of the method pioneered by Zhang, Liao & Yao in which the motion of the compact object can be tracked using wind X-ray absorption lines. We present the velocity measurements of the thermal wind lines observed in the X-ray spectrum of a few low-mass X-ray binaries: GX 13+1, H 1743-322, GRO J1655-40 and GRS 1915+105. We find that the variability in the velocity of the wind lines in about all of the sources is larger than conceivable radial velocity variations of the compact object. GX 13+1 provides a potential exception, although it would require the red giant star to be massive with a mass of ≈5-6 M⊙. We conclude that the variability of the source luminosity occurring on a time-scale of days/months can affect the outflow properties making it difficult to track the orbital motion of the compact object using current observations. Given the intrinsic variability of the outflows we suggest that low-mass X-ray binaries showing stable coronae instead of an outflow (e.g. 4U 1254-69, MXB 1659-29, 4U 1624-49) could be more suitable targets for tracking the orbital motion of the compact object.

  7. LOW-MASS TERTIARY COMPANIONS TO SPECTROSCOPIC BINARIES. I. COMMON PROPER MOTION SURVEY FOR WIDE COMPANIONS USING 2MASS

    SciTech Connect

    Allen, Peter R.; Burgasser, Adam J.; Faherty, Jacqueline K.; Kirkpatrick, J. Davy

    2012-08-15

    We report the first results of a multi-epoch search for wide (separations greater than a few tens of AU), low-mass tertiary companions of a volume-limited sample of 118 known spectroscopic binaries within 30 pc of the Sun, using the Two Micron All Sky Survey Point Source Catalog and follow-up observations with the KPNO and CTIO 4 m telescopes. Note that this sample is not volume complete but volume limited, and, thus, there is incompleteness in our reported companion rates. We are sensitive to common proper motion companions with separations from roughly 200 AU to 10,000 AU ({approx}10'' {yields} {approx} 10'). From 77 sources followed-up to date, we recover 11 previously known tertiaries, 3 previously known candidate tertiaries, of which 2 are spectroscopically confirmed and 1 rejected, and 3 new candidates, of which 2 are confirmed and 1 rejected. This yields an estimated wide tertiary fraction of 19.5{sup +5.2}{sub -3.7}%. This observed fraction is consistent with predictions set out in star formation simulations where the fraction of wide, low-mass companions to spectroscopic binaries is >10%.

  8. The Ionized and Variable Outflow in the Low-Mass X-Ray Binary GX 13+1

    NASA Astrophysics Data System (ADS)

    Allen, Jessamyn; Schulz, Norbert S.; Homan, Jeroen; Chakrabarty, Deepto

    2016-04-01

    We present the analysis of 7 Chandra HETG and 16 simultaneous RXTE PCA observations of GX 13+1, a persistent neutron star low-mass X-ray binary. The observations cover activity between 2002 and 2011. The 0.5-10 keV continuum was consistent with a two component model, either a blackbody plus power law or multicolor disk and blackbody across luminosities of (5-7)x1037 erg sec-1, modified by a neutral absorption column requiring a silicon overabundance. We have identified significantly blue-shifted (voutflow > 500 km sec-1) Kα Fe, Ca, S, and Si hydrogen-like lines in all HETG observations, as well hydrogen-like Ar and Mg lines in the majority of observations. The significant outflow can be modeled as a photoionized plasma with an ionization parameter ≥ 3.5. For the first time we map the occurrence of these wind outflows onto the color-color diagram of GX 13+1 and compare their location with that of the jet outflows in this system. We will further present variable X-ray properties of the wind in GX 13+1 and discuss suggested launching mechanisms as well as how its properties relate to the wind-accretion state in low-mass X-ray binaries.

  9. HIGH RESOLUTION H{alpha} IMAGES OF THE BINARY LOW-MASS PROPLYD LV 1 WITH THE MAGELLAN AO SYSTEM

    SciTech Connect

    Wu, Y.-L.; Close, L. M.; Males, J. R.; Follette, K.; Morzinski, K.; Kopon, D.; Rodigas, T. J.; Hinz, P.; Puglisi, A.; Esposito, S.; Pinna, E.; Riccardi, A.; Xompero, M.; Briguglio, R.

    2013-09-01

    We utilize the new Magellan adaptive optics system (MagAO) to image the binary proplyd LV 1 in the Orion Trapezium at H{alpha}. This is among the first AO results in visible wavelengths. The H{alpha} image clearly shows the ionization fronts, the interproplyd shell, and the cometary tails. Our astrometric measurements find no significant relative motion between components over {approx}18 yr, implying that LV 1 is a low-mass system. We also analyze Large Binocular Telescope AO observations, and find a point source which may be the embedded protostar's photosphere in the continuum. Converting the H magnitudes to mass, we show that the LV 1 binary may consist of one very-low-mass star with a likely brown dwarf secondary, or even plausibly a double brown dwarf. Finally, the magnetopause of the minor proplyd is estimated to have a radius of 110 AU, consistent with the location of the bow shock seen in H{alpha}.

  10. Searching for gravitational waves from low mass x-ray binaries

    NASA Astrophysics Data System (ADS)

    Messenger, Christopher; Vecchio, Alberto

    2004-03-01

    Accreting neutron stars in binary systems, and Sco X-1 in particular, are considered one of the prime astrophysical targets for Earth-based gravitational wave laser interferometers. Here we discuss a data analysis strategy that we have developed for this class of systems which is now being applied to the science data collected by GEO600 and LIGO.

  11. Expected Large Synoptic Survey Telescope (LSST) Yield of Eclipsing Binary Stars

    NASA Astrophysics Data System (ADS)

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

    2011-08-01

    In this paper, we estimate the Large Synoptic Survey Telescope (LSST) yield of eclipsing binary stars, which will survey ~20,000 deg2 of the southern sky during a period of 10 years in six photometric passbands to r ~ 24.5. We generate a set of 10,000 eclipsing binary light curves sampled to the LSST time cadence across the whole sky, with added noise as a function of apparent magnitude. This set is passed to the analysis-of-variance period finder to assess the recoverability rate for the periods, and the successfully phased light curves are passed to the artificial-intelligence-based pipeline ebai to assess the recoverability rate in terms of the eclipsing binaries' physical and geometric parameters. We find that, out of ~24 million eclipsing binaries observed by LSST with a signal-to-noise ratio >10 in mission lifetime, ~28% or 6.7 million can be fully characterized by the pipeline. Of those, ~25% or 1.7 million will be double-lined binaries, a true treasure trove for stellar astrophysics.

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

    SciTech Connect

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

    2011-08-15

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

  13. Search with UVES and X-Shooter for signatures of the low-mass secondary in the post common-envelope binary AA Doradus

    NASA Astrophysics Data System (ADS)

    Hoyer, D.; Rauch, T.; Werner, K.; Hauschildt, P. H.; Kruk, J. W.

    2015-06-01

    Context. AA Dor is a close, totally eclipsing, post common-envelope binary with an sdOB-type primary star and an extremely low-mass secondary star, located close to the mass limit of stable central hydrogen burning. Within error limits, it may either be a brown dwarf or a late M-type dwarf. Aims: We aim to extract the secondary's contribution to the phase-dependent composite spectra. The spectrum and identified lines of the secondary decide on its nature. Methods: In January 2014, we measured the phase-dependent spectrum of AA Dor with X-Shooter over one complete orbital period. Since the secondary's rotation is presumable synchronized with the orbital period, its surface strictly divides into a day and night side. Therefore, we may obtain the spectrum of its cool side during its transit and of its hot, irradiated side close to its occultation. We developed the Virtual Observatory (VO) tool TLISA to search for weak lines of a faint companion in a binary system. We successfully applied it to the observations of AA Dor. Results: We identified 53 spectral lines of the secondary in the ultraviolet-blue, visual, and near-infrared X-Shooter spectra that are strongest close to its occultation. We identified 57 (20 additional) lines in available Ultraviolet and Visual Echelle Spectrograph (UVES) spectra from 2001. The lines are mostly from C ii-iii and O ii, typical for a low-mass star that is irradiated and heated by the primary. We verified the orbital period of P = 22 597.033201 ± 0.00007 s and determined the orbital velocity K_sec = 232.9+16.6-6.5 km s-1 of the secondary. The mass of the secondary is M_sec = 0.081+0.018-0.010 M_⊙ and, hence, it is not possible to reliably determine a brown dwarf or an M-type dwarf nature. Conclusions: Although we identified many emission lines of the secondary's irradiated surface, the resolution and signal-to-noise ratio of our UVES and X-Shooter spectra are not good enough to extract a good spectrum of the secondary

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

    NASA Astrophysics Data System (ADS)

    Bloemen, S.; Degroote, P.; Conroy, K.; Hambleton, K. M.; Giammarco, J. M.; Pablo, H.; Prša, A.

    2013-02-01

    Recent ultra-high precision observations of eclipsing binaries, especially data acquired by the Kepler satellite, have made accurate light curve modelling increasingly challenging but also more rewarding. In this contribution, we discuss low-amplitude signals in light curves that can now be used to derive physical information about eclipsing binaries but that were unaccessible before the Kepler era. A notable example is the detection of Doppler beaming, which leads to an increase in flux when a star moves towards the satellite and a decrease in flux when it moves away. Similarly, Rømer delays, or light travel time effects, also have to taken into account when modelling the supreme quality data that is now available. The detection of offsets between primary and secondary eclipse phases in binaries with extreme mass ratios, and the observation of Rømer delays in the signals of pulsators in binary stars, have allowed us to determine the orbits of several binaries without the need for spectroscopy. A third example of a small-scale effect that has to be taken into account when modelling specific binary systems, are lensing effects. A new binary light curve modelling code, PHOEBE 2.0, that takes all these effect into account is currently being developed.

  15. A New, Young, Low-Mass Spectroscopic Binary Without a Home

    NASA Astrophysics Data System (ADS)

    Flagg, Laura S.; Shkolnik, Evgenya L.; Weinberger, Alycia J.; Bowler, Brendan P.; Kraus, Adam L.; Liu, Michael C.

    2016-01-01

    We have discovered that 2MASS 08355977-3042306 is an accreting K7, double-lined, spectroscopic binary younger than ~20 Myr. The age of a dispersed young star can best be determined if it is a member of a known young moving group. However, the three dimensional space velocities (UVW) we calculate using radial velocity measurements, proper motions, and plausible photometric distances make membership in any known young moving group unlikely.

  16. SpeX spectroscopy of unresolved very low mass binaries. II. Identification of 14 candidate binaries with late-M/early-L and T dwarf components

    SciTech Connect

    Bardalez Gagliuffi, Daniella C.; Burgasser, Adam J.; Nicholls, Christine P.; Gelino, Christopher R.; Looper, Dagny L.; Schmidt, Sarah J.; Cruz, Kelle; West, Andrew A.; Gizis, John E.; Metchev, Stanimir

    2014-10-20

    Multiplicity is a key statistic for understanding the formation of very low mass (VLM) stars and brown dwarfs. Currently, the separation distribution of VLM binaries remains poorly constrained at small separations (≤1 AU), leading to uncertainty in the overall binary fraction. We approach this problem by searching for late-M/early-L plus T dwarf spectral binaries whose combined light spectra exhibit distinct peculiarities, allowing for separation-independent identification. We define a set of spectral indices designed to identify these systems, and we use a spectral template fitting method to confirm and characterize spectral binary candidates from a library of 815 spectra from the SpeX Prism Spectral Libraries. We present 11 new binary candidates, confirm 3 previously reported candidates, and rule out 2 previously identified candidates, all with primary and secondary spectral types in the range M7-L7 and T1-T8, respectively. We find that subdwarfs and blue L dwarfs are the primary contaminants in our sample and propose a method for segregating these sources. If confirmed by follow-up observations, these systems may add to the growing list of tight separation binaries, whose orbital properties may yield further insight into brown dwarf formation scenarios.

  17. High Resolution Imaging of Very Low Mass Spectral Binaries: Three Resolved Systems and Detection of Orbital Motion in an L/T Transition Binary

    NASA Astrophysics Data System (ADS)

    Bardalez Gagliuffi, Daniella C.; Gelino, Christopher R.; Burgasser, Adam J.

    2015-11-01

    We present high resolution Laser Guide Star Adaptive Optics imaging of 43 late-M, L and T dwarf systems with Keck/NIRC2. These include 17 spectral binary candidates, systems whose spectra suggest the presence of a T dwarf secondary. We resolve three systems: 2MASS J1341-3052, SDSS J1511+0607 and SDSS J2052-1609 the first two are resolved for the first time. All three have projected separations <8 AU and estimated periods of 14-80 years. We also report a preliminary orbit determination for SDSS J2052-1609 based on six epochs of resolved astrometry between 2005 and 2010. Among the 14 unresolved spectral binaries, 5 systems were confirmed binaries but remained unresolved, implying a minimum binary fraction of {47}-11+12% for this sample. Our inability to resolve most of the spectral binaries, including the confirmed binaries, supports the hypothesis that a large fraction of very low mass systems have relatively small separations and are missed with direct imaging. Some of the data presented herein were obtained at the W.M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W.M. Keck Foundation.

  18. Light curve solutions of the eclipsing Kepler binaries KIC 8088354 and KIC 3241619

    NASA Astrophysics Data System (ADS)

    Kjurkchieva, Diana; Atanasova, Teodora

    2016-01-01

    We carried out light curve solutions of two detached eclipsing binaries with circular orbits observed by Kepler: KIC 8088354 and KIC 3241619. We established that: (i) The eclipses of KIC 8088354 are partial while KIC 3241619 undergoes total eclipse; (ii) the components of both targets are of spectral types G-K; (iii) the radii of the components of the objects differ by 20-30 %; (iv) the relative luminosities of their secondaries are considerably smaller than those of the primaries. The global parameters of KIC 8088354 and KIC 3241619 (temperatures, luminosities, radii and masses of the components) were found to obey satisfactorily the empirical relations of MS stars. We analyzed the additional short-term and long-term variability of the targets superposed on the eclipses.

  19. Origin of apparent period variations in eclipsing post-common-envelope binaries

    NASA Astrophysics Data System (ADS)

    Zorotovic, M.; Schreiber, M. R.

    2013-01-01

    Context. Apparent period variations detected in several eclipsing, close-compact binaries are frequently interpreted as being caused by circumbinary giant planets. This interpretation raises the question of the origin of the potential planets that must have either formed in the primordial circumbinary disk, together with the host binary star, and survived its evolution into a close-compact binary or formed in a post-common-envelope circumbinary disk that remained bound to the post-common-envelope binary (PCEB). Aims: Here we combine current knowledge of planet formation and the statistics of giant planets around primordial and evolved binary stars with the theory of close-compact binary star evolution aiming to derive new constraints on possible formation scenarios. Methods: We compiled a comprehensive list of observed eclipsing PCEBs, estimated the fraction of systems showing apparent period variations, reconstructed the evolutionary history of the PCEBs, and performed binary population models of PCEBs to characterize their main sequence binary progenitors. We reviewed the currently available constraints on the fraction of PCEB progenitors that host circumbinary giant planets. Results: We find that the progenitors of PCEBs are very unlikely to be frequent hosts of giant planets (≲10 per cent), while the frequency of PCEBs with observed apparent period variations is very high (~90 per cent). Conclusions: The variations in eclipse timings measured in eclipsing PCEBs are probably not caused by first-generation planets that survived common-envelope evolution. The remaining options for explaining the observed period variations are second-generation planet formation or perhaps variations in the shape of a magnetically active secondary star. We suggest observational tests for both options. Appendix A is available in electronic form at http://www.aanda.org

  20. Data Mining Analysis for Eclipsing Binary TrES-Cyg3-04450

    NASA Astrophysics Data System (ADS)

    Hinzel, D. H.

    2015-12-01

    A data mining algorithm was utilized to analyze Johnson V-band charge-coupled device (CCD) photometric data of an object that were taken during a wide field survey of a region in the constellation Cygnus. That algorithm was the Date Compensated Discrete Fourier Transform (DC DFT) which is part of the AAVSO VSTAR applications software. This analysis clearly indicated that the object under study is a detached eclipsing binary, specifically an EA β Persei-type (Algol) eclipsing system, with an orbital period of 2.0664 days. Neither the type nor period of this eclipsing binary had been characterized up to this point. This object has been given the AAVSO designation TrES-Cyg3-04450 and the AUID 000-BLL-484.

  1. Resolving the Discrepancy of Low-Mass Stars with IGRINS

    NASA Astrophysics Data System (ADS)

    Riddle, Andrew; Kraus, Adam L.

    2015-01-01

    Observed properties of low-mass stars (M < 0.8 solar msses) have been found to be in disagreement with stellar models, the observed radii being inflated and the observed temperatures being too low. To study this discrepancy, we are observing a sample of low-mass eclipsing binaries using the 2.7-m Harlan J. Smith telescope at McDonald Observatory as well as the LCOGT network to increase the number of well-characterized systems. We are also using IGRINS, a new high resolution (R=40,000) IR (H+K) spectrograph on the 2.7-m HJST, to measure the fundamental stellar parameters (Teff, R, M, abundances, activity) of a sample of eclipsing binaries consisting of two low-mass components. Finally, to calibrate these eclipsing binaries, we are observing a temperature calibration sample of single M dwarfs with precise temperature measurements from interferometry and a metallicity calibration sample of M dwarfs in wide binaries with solar-type stars. Relationships between these parameters will help us better understand the discrepancy between models and observed properties of low-mass stars.

  2. VizieR Online Data Catalog: Eclipsing binaries with candidate CP stars (North+ 1997)

    NASA Astrophysics Data System (ADS)

    North, P.; Studer, M.; Kunzli, M.

    1997-02-01

    Photometry in the Geneva systems and radial velocities are used to determine the fundamental parameters of three eclipsing binaries, two of which having been classified as chemically peculiar and the third having relatively narrow lines. For a description of the Geneva photometric system, see e.g. (3 data files).

  3. Five eccentric eclipsing binaries with the relatively short periods of apsidal motion

    NASA Astrophysics Data System (ADS)

    Kucakova, H.; Wolf, M.

    2013-11-01

    This text is focused on some information and results of the analysis of the selected eccentric eclipsing binaries with relatively short periods of apsidal motion - V785 Cas, V821 Cas, V796 Cyg, V398 Lac, and V871 Per. Further and more detailed information can be found in the paper in A&A (M. Wolf et al. 2013).

  4. HIDES spectroscopy of bright detached eclipsing binaries from the Kepler field - I. Single-lined objects

    NASA Astrophysics Data System (ADS)

    Hełminiak, K. G.; Ukita, N.; Kambe, E.; Kozłowski, S. K.; Sybilski, P.; Ratajczak, M.; Maehara, H.; Konacki, M.

    2016-09-01

    We present results of our spectroscopic observations of nine detached eclipsing binaries (DEBs), selected from the Kepler Eclipsing Binary Catalog, that only show one set of spectral lines. Radial velocities (RVs) were calculated from the high-resolution spectra obtained with the HIgh-Dispersion Echelle Spectrograph (HIDES) instrument, attached to the 1.88-m telescope at the Okayama Astrophysical Observatory, and from the public Apache Point Observatory Galactic Evolution Experiment archive. In our sample, we found five single-lined binaries, with one component dominating the spectrum. The orbital and light-curve solutions were found for four of them, and compared with isochrones, in order to estimate absolute physical parameters and evolutionary status of the components. For the fifth case, we only update the orbital parameters, and estimate the properties of the unseen star. Two other systems show orbital motion with a period known from the eclipse timing variations (ETVs). For these we obtained parameters of outer orbits, by translating the ETVs to RVs of the centre of mass of the eclipsing binary, and combining with the RVs of the outer star. Of the two remaining ones, one is most likely a blend of a faint background DEB with a bright foreground star, which lines we see in the spectra, and the last case is possibly a quadruple bearing a sub-stellar mass object. Where possible, we compare our results with literature, especially with results from asteroseismology. We also report possible detections of solar-like oscillations in our RVs.

  5. Accretion turnoff and rapid evaporation of very light secondaries in low-mass X-ray binaries

    NASA Technical Reports Server (NTRS)

    Ruderman, M.; Shaham, J.; Tavani, M.

    1989-01-01

    The illumination of companion stars in very low mass X-ray binaries by various kinds of radiation from the neighborhood of the neutron star after accretion has terminated or during accretion is considered. If a neutron star's spun-up period approaches 0.001 s, pulsar kHz radiation can quench accretion by pushing surrounding plasma away from the neutron star, and may leave the companion to be evaporated by the high-energy radiation component expected from an 'isolated' millisecond radiopulsar. Expected accretion-powered MeV gamma-rays and e(+ or -) winds may also be effective in evaporating dwarf companions. Neutron star spin-down energy release may sustain the power in these radiation mechanisms even while accretion falls. Accretion-powered soft X-rays may speed the mass loss of highly evolved dwarf companions, particularly those with a large fraction of carbon and oxygen.

  6. How young are the low-mass X-ray binaries? Conclusions from a flux-limited sample

    NASA Astrophysics Data System (ADS)

    Naylor, T.; Podsiadlowski, Ph.

    1993-06-01

    Low-mass X-ray binaries fall into two classes on the basis of their X-ray properties. Using a flux-limited sample from the Ariel V Sky Survey, we show that the class sometimes referred to as the X-ray bursters is associated with the Galactic disk, and probably has an age of only 10 exp 7 to 10 exp 8 yr, much younger than was previously thought. The short lifetime of these 'disk sources' explains why there are so many millisecond pulsars, and how a system such as Her X-1 can have a relatively massive secondary. Conversely, the 'bright blue sources' seem to be associated with a highly flattened, old, metal-rich inner bulge population.

  7. The Infrared Variability of GX17+2 and Low-Mass X-ray Binary Jets

    NASA Astrophysics Data System (ADS)

    McNamara, Bernard J.; Bornak, J.; Harrison, T.; Rupen, M.

    2007-12-01

    GX17+2 is a low-mass X-ray binary. It is also classified as a Z-source since it exhibits a distinctive Z-pattern in its X-ray color-color plot. GX17+2 is located in the direction of the galactic center and is not detectable at optical wavelengths. Its emission varies by over 4 magnitudes in the infrared. A number of explanations have been advanced to explain this variabilty. Based upon KPNO and Smarts IR observations, we suggest that it arises from a sychrotron jet which is periodically visible along our line of sight. This circumstance provides a rather unique opportunity to quantify a number of jet properties such as its opening angle, the sharpness of the jet boundaries, its variability, and the infrared emission uniformity across the jet.

  8. Radiation-driven evolution of low-mass x-ray binaries and the formation of millisecond pulsars

    SciTech Connect

    Tavani, M. California Univ., Berkeley, CA . Dept. of Astronomy)

    1991-08-08

    Recent data on low-mass X-ray binaries (LMXBs) and millisecond pulsars (MSPs) pose a challenge to evolutionary theories which neglect the effects of disk and comparison irradiation. Here we discuss the main features of a radiation-driven (RD) evolutionary model that may be applicable to several LMXBs. According to this model, radiation from the accreting compact star in LMXBs vaporizes'' the accretion disk and the companion star by driving a self-sustained mass loss until a sudden accretion-turn off occurs. The main characteristics of the RD-evolution are: (1) lifetime of RD-LMXB's is of order 10{sup 7} years or less; (2) both the orbital period gap and the X-ray luminosity may be consequences of RD-evolution of LMXB's containing lower main sequence and degeneration companion stars; (3) the companion star may transfer mass to the primary even if it underfills its Roche lobe; (4) a class of recycled MSPs can continue to vaporize the low-mass companions by a strong pulsar wind even after the accretion turn-off; (5) the RD-evolutionary model resolves the apparent statistical descrepancy between the number of MSPs and their LMXB progenitors in the Galaxy. We discuss the implications of the discovery of single MSPs in low-density globular clusters and the recent measurements of short orbital timescales of four LMXBs. 34 refs., 3 figs., 2 tabs.

  9. VISUAL ORBIT OF THE LOW-MASS BINARY GJ 164 AB

    SciTech Connect

    Martinache, Frantz; Rojas-Ayala, Barbara; Lloyd, James P.; Ireland, Michael J.; Tuthill, Peter G.

    2009-04-20

    We report seven successful observations of the astrometric binary GJ 164 AB system with aperture masking interferometry. The companion, with a near-infrared contrast of 5:1 was detected beyond the formal diffraction limit. Combined with astrometric observations from the literature, these observations fix the parallax of the system, and allow a model-independent mass determination of both components. We find the mass of GJ 164 B to be 0.096 {+-} 0.008 M {sub sun}. With data taken with the newly commissioned TripleSpec spectrograph, we examine GJ 164's near-infrared spectral features and compare them to a sample of M dwarfs of known metallicity. Models are not consistent with color and mass, requiring a very young age to accommodate a secondary too luminous, a scenario ruled out by the kinematics.

  10. Multi-periodic pulsations of a stripped red-giant star in an eclipsing binary system.

    PubMed

    Maxted, Pierre F L; Serenelli, Aldo M; Miglio, Andrea; Marsh, Thomas R; Heber, Ulrich; Dhillon, Vikram S; Littlefair, Stuart; Copperwheat, Chris; Smalley, Barry; Breedt, Elmé; Schaffenroth, Veronika

    2013-06-27

    Low-mass white-dwarf stars are the remnants of disrupted red-giant stars in binary millisecond pulsars and other exotic binary star systems. Some low-mass white dwarfs cool rapidly, whereas others stay bright for millions of years because of stable fusion in thick surface hydrogen layers. This dichotomy is not well understood, so the potential use of low-mass white dwarfs as independent clocks with which to test the spin-down ages of pulsars or as probes of the extreme environments in which low-mass white dwarfs form cannot fully be exploited. Here we report precise mass and radius measurements for the precursor to a low-mass white dwarf. We find that only models in which this disrupted red-giant star has a thick hydrogen envelope can match the strong constraints provided by our data. Very cool low-mass white dwarfs must therefore have lost their thick hydrogen envelopes by irradiation from pulsar companions or by episodes of unstable hydrogen fusion (shell flashes). We also find that this low-mass white-dwarf precursor is a type of pulsating star not hitherto seen. The observed pulsation frequencies are sensitive to internal processes that determine whether this star will undergo shell flashes. PMID:23803845

  11. VizieR Online Data Catalog: Near-IR spectroscopy of low-mass binaries and brown dwarfs (Mace, 2014)

    NASA Astrophysics Data System (ADS)

    Mace, G. N.

    2014-05-01

    The mass of a star at formation determines its subsequent evolution and demise. Low-mass stars are the most common products of star formation and their long main-sequence lifetimes cause them to accumulate over time. Star formation also produces many substellar-mass objects known as brown dwarfs, which emerge from their natal molecular clouds and continually cool as they age, pervading the Milky Way. Low-mass stars and brown dwarfs exhibit a wide range of physical characteristics and their abundance make them ideal subjects for testing formation and evolution models. I have examined a pair of pre-main sequence spectroscopic binaries and used radial velocity variations to determine orbital solutions and mass ratios. Additionally, I have employed synthetic spectra to estimate their effective temperatures and place them on theoretical Hertzsprung-Russell diagrams. From this analysis I discuss the formation and evolution of young binary systems and place bounds on absolute masses and radii. I have also studied the late-type T dwarfs revealed by the Wide-field Infrared Survey Explorer (WISE). This includes the exemplar T8 subdwarf Wolf 1130C, which has the lowest inferred metallicity in the literature and spectroscopic traits consistent with old age. Comparison to synthetic spectra implies that the dispersion in near-infrared colors of late-type T dwarfs is a result of age and/or thin sul de clouds. With the updated census of the L, T, and Y dwarfs we can now study specific brown dwarf subpopulations. Finally, I present a number of future studies that would develop our understanding of the physical qualities of T dwarf color outliers and disentangle the tracers of age and atmospheric properties. The thesis is available at: http://www.astro.ucla.edu/~gmace/thesis.html (7 data files).

  12. Low-mass X-ray binary MAXI J1421-613 observed by MAXI GSC and Swift XRT

    NASA Astrophysics Data System (ADS)

    Serino, Motoko; Shidatsu, Megumi; Ueda, Yoshihiro; Matsuoka, Masaru; Negoro, Hitoshi; Yamaoka, Kazutaka; Kennea, Jamie A.; Fukushima, Kosuke; Nagayama, Takahiro

    2015-04-01

    Monitor of All sky X-ray Image (MAXI) discovered a new outburst of an X-ray transient source named MAXI J1421-613. Because of the detection of three X-ray bursts from the source, it was identified as a neutron star low-mass X-ray binary. The results of data analyses of the MAXI GSC (Gas Slit Camera) and the Swift XRT (X-Ray Telescope) follow-up observations suggest that the spectral hardness remained unchanged during the first two weeks of the outburst. All the XRT spectra in the 0.5-10 keV band can be well explained by thermal Comptonization of multi-color disk blackbody emission. The photon index of the Comptonized component is ≈ 2, which is typical of low-mass X-ray binaries in the low/hard state. Since X-ray bursts have a maximum peak luminosity, it is possible to estimate the (maximum) distance from its observed peak flux. The peak flux of the second X-ray burst, which was observed by the GSC, is about 5 photons cm-2 s-1. By assuming a blackbody spectrum of 2.5 keV, the maximum distance to the source is estimated as 7 kpc. The position of this source is contained by the large error regions of two bright X-ray sources detected with Orbiting Solar Observatory-7 (OSO-7) in the 1970s. Besides this, no past activities at the XRT position are reported in the literature. If MAXI J1421-613 is the same source as (one of) these, the outburst observed with MAXI may have occurred after a quiescence of 30-40 years.

  13. DEEP, LOW-MASS RATIO OVERCONTACT BINARY SYSTEMS. XII. CK BOOTIS WITH POSSIBLE CYCLIC MAGNETIC ACTIVITY AND ADDITIONAL COMPANION

    SciTech Connect

    Yang, Y.-G.; Qian, S.-B.; Soonthornthum, B. E-mail: qsb@ynao.ac.cn

    2012-05-15

    We present precision CCD photometry, a period study, and a two-color simultaneous Wilson code solution of the short-period contact binary CK Bootis. The asymmetric light curves were modeled by a dark spot on the primary component. The result identifies that CK Boo is an A-type W UMa binary with a high fillout of f = 71.7({+-} 4.4)%. From the O - C curve, it is found that the orbital period changes in a complicated mode, i.e., a long-term increase with two sinusoidal variations. One cyclic oscillation with a period of 10.67({+-} 0.20) yr may result from magnetic activity cycles, which are identified by the variability of Max. I - Max. II. Another sinusoidal variation (i.e., A = 0.0131 days({+-} 0.0009 days) and P{sub 3} = 24.16({+-} 0.64) yr) may be attributed to the light-time effect due to a third body. This kind of additional companion can extract angular momentum from the central binary system. The orbital period secularly increases at a rate of dP/dt = +9.79 ({+-}0.80) Multiplication-Sign 10{sup -8} days yr{sup -1}, which may be interpreted by conservative mass transfer from the secondary to the primary. This kind of deep, low-mass ratio overcontact binaries may evolve into a rapid-rotating single star, only if the contact configuration do not break down at J{sub spin} > (1/3)J{sub orb}.

  14. A Triple Eclipsing System as a Test Case for Close Binary Formation through Kozai Cycles

    NASA Astrophysics Data System (ADS)

    Conroy, K. E.; Prša, A.; Stassun, K. G.

    2015-07-01

    Kozai cycles and tidal friction of a binary with a tertiary companion is one of the leading theories for the formation of close binary systems by tightening the orbit of the inner binary. According to simulations, such systems should evolve into tight inner binaries with eccentric tertiary companions on wide orbits, and importantly, predict the tertiary to have an orbital inclination misaligned relative to the plane of the inner binary, with an angle of misalignment that peaks strongly around 40 degrees. KIC 2835289 is a triple system comprising a ˜0.9-day inner binary and a tertiary on a ˜750-day orbit. The tertiary was identified through our eclipse timing variations and our finding of a tertiary eclipse event in the Kepler data. Here we show, using photodynamical modeling of the system, that the tertiary in this system is on an eccentric orbit inclined with respect to the inner binary, in agreement with theoretical prediction. KIC 2835289 is thus the first known triple system that directly attests to the key predictions of Kozai cycles and tidal friction as a mechanism to tighten binary star systems.

  15. Detecting Circumbinary Planets Using Eclipse Timing of Binary Stars - From Simulations to Observations

    NASA Astrophysics Data System (ADS)

    Sybilski, Piotr; Konacki, M.; Kozlowski, S. K.

    2010-05-01

    The Light-Time Effect (LTE) occurs whenever the distance between the observer and any kind of periodic signal occurring in space changes. The usual cause of this is the reflex motion about the system's barycenter due to the gravitational influence of one or more additional bodies. With a sufficient precision of the times of eclipses, the eclipse timing can be used to detect substellar or even planetary mass companions. The main goal of the poster is to investigate the potential of the photometry based eclipse timing of binary stars as a method of detecting circumbinary planets. In the models we assume that the companion orbits a binary star in a circular Keplerian orbit. We analyze throug the numerical simulations both the space and ground based photometry cases. In particular, we study the usefulness of the on-going COROT and Kepler missions in detecting circumbinary planets. We determine the sensitivity of the eclipse timing technique to circumbinary planets for the ground and space based photometric observations. We provide suggestions for the best targets, observing strategies and instruments for the eclipse timing method. Finally, we present some preliminary results comparing simulations and real observations.

  16. Simultaneous CCD Photometry of Two Eclipsing Binary Stars in Pegasus - Part 1: KW Pegasi

    NASA Astrophysics Data System (ADS)

    Alton, K. B.

    2013-06-01

    The coincidental location of BX Peg and KW Peg in the same field-of-view captured by the primary imaging system at UnderOak Observatory (UO) provided an opportunity to study both variable stars from the same exposures. Herein new findings for the eclipsing binary KW Peg will be presented while those from BX Peg will be discussed in a separate paper (Part 2). KW Peg, described as an "Algol type" eclipsing variable (P = 0.816402 d), is only reported in a single work published over twenty years ago. Photometric data collected in three bandpasses (B, V, and Ic), produced eight new times of minimum for KW Peg. These were used to update the linear ephemeris and further analyze potential changes in orbital periodicity by examining the available history of eclipse timings. In addition, synthetic fitting of light curves by Roche modeling was accomplished with programs employing the Wilson-Devinney code. Results from the present study provide a reasonable case for classifying KW Peg as a short-period RS CVn eclipsing binary rather than Algol-like. The primary star in KW Peg would appear to be a late stage G9V-K0V dwarf whereas the secondary is a slightly cooler K0-K1 companion. The eclipse-timing diagram for KW Peg is quite simple and indicates that, on average, the orbital period for this system has remained fairly constant over the past two decades.

  17. ANALYSIS OF DETACHED ECLIPSING BINARIES NEAR THE TURNOFF OF THE OPEN CLUSTER NGC 7142

    SciTech Connect

    Sandquist, Eric L.; Serio, Andrew W.; Orosz, Jerome; Shetrone, Matthew E-mail: aserio@gemini.edu E-mail: shetrone@astro.as.utexas.edu

    2013-08-01

    We analyze extensive BVR{sub C}I{sub C} photometry and radial velocity measurements for three double-lined deeply eclipsing binary stars in the field of the old open cluster NGC 7142. The short period (P = 1.9096825 days) detached binary V375 Cep is a high probability cluster member, and has a total eclipse of the secondary star. The characteristics of the primary star (M = 1.288 {+-} 0.017 M{sub Sun }) at the cluster turnoff indicate an age of 3.6 Gyr (with a random uncertainty of 0.25 Gyr), consistent with earlier analysis of the color-magnitude diagram. The secondary star (M = 0.871 {+-} 0.008 M{sub Sun }) is not expected to have evolved significantly, but its radius is more than 10% larger than predicted by models. Because this binary system has a known age, it is useful for testing the idea that radius inflation can occur in short period binaries for stars with significant convective envelopes due to the inhibition of energy transport by magnetic fields. The brighter star in the binary also produces a precision estimate of the distance modulus, independent of reddening estimates: (m - M){sub V} = 12.86 {+-} 0.07. The other two eclipsing binary systems are not cluster members, although one of the systems (V2) could only be conclusively ruled out as a present or former member once the stellar characteristics were determined. That binary is within 0. Degree-Sign 5 of edge-on, is in a fairly long-period eccentric binary, and contains two almost indistinguishable stars. The other binary (V1) has a small but nonzero eccentricity (e = 0.038) in spite of having an orbital period under 5 days.

  18. Analysis of Detached Eclipsing Binaries near the Turnoff of the Open Cluster NGC 7142

    NASA Astrophysics Data System (ADS)

    Sandquist, Eric L.; Shetrone, Matthew; Serio, Andrew W.; Orosz, Jerome

    2013-08-01

    We analyze extensive BVRCIC photometry and radial velocity measurements for three double-lined deeply eclipsing binary stars in the field of the old open cluster NGC 7142. The short period (P = 1.9096825 days) detached binary V375 Cep is a high probability cluster member, and has a total eclipse of the secondary star. The characteristics of the primary star (M = 1.288 ± 0.017 M ⊙) at the cluster turnoff indicate an age of 3.6 Gyr (with a random uncertainty of 0.25 Gyr), consistent with earlier analysis of the color-magnitude diagram. The secondary star (M = 0.871 ± 0.008 M ⊙) is not expected to have evolved significantly, but its radius is more than 10% larger than predicted by models. Because this binary system has a known age, it is useful for testing the idea that radius inflation can occur in short period binaries for stars with significant convective envelopes due to the inhibition of energy transport by magnetic fields. The brighter star in the binary also produces a precision estimate of the distance modulus, independent of reddening estimates: (m - M) V = 12.86 ± 0.07. The other two eclipsing binary systems are not cluster members, although one of the systems (V2) could only be conclusively ruled out as a present or former member once the stellar characteristics were determined. That binary is within 0.°5 of edge-on, is in a fairly long-period eccentric binary, and contains two almost indistinguishable stars. The other binary (V1) has a small but nonzero eccentricity (e = 0.038) in spite of having an orbital period under 5 days.

  19. The Reverberation Lag in the Low-mass X-ray Binary H1743-322

    NASA Astrophysics Data System (ADS)

    De Marco, Barbara; Ponti, Gabriele

    2016-07-01

    The evolution of the inner accretion flow of a black hole X-ray binary during an outburst is still a matter of active research. X-ray reverberation lags are powerful tools for constraining disk–corona geometry. We present a study of X-ray lags in the black hole transient H1743-322. We compared the results obtained from analysis of all the publicly available XMM-Newton observations. These observations were carried out during two different outbursts that occurred in 2008 and 2014. During all the observations the source was caught in the hard state and at similar luminosities ({L}3-10{keV}/{L}{Edd}˜ 0.004). We detected a soft X-ray lag of ˜60 ms, most likely due to thermal reverberation. We did not detect any significant change of the lag amplitude among the different observations, indicating a similar disk–corona geometry at the same luminosity in the hard state. On the other hand, we observe significant differences between the reverberation lag detected in H1743-322 and in GX 339-4 (at similar luminosities in the hard state), which might indicate variations of the geometry from source to source.

  20. A Computational Guide to Physics of Eclipsing Binaries. I. Demonstrations and Perspectives

    NASA Astrophysics Data System (ADS)

    Prša, A.; Zwitter, T.

    2005-07-01

    PHOEBE (PHysics Of Eclipsing BinariEs) is a modeling package for eclipsing binary stars, built on top of the widely used WD program of Wilson & Devinney. This introductory paper gives an overview of the most important scientific extensions (incorporating observational spectra of eclipsing binaries into the solution-seeking process, extracting individual temperatures from observed color indices, main-sequence constraining, and proper treatment of the reddening), numerical innovations (suggested improvements to WD's differential corrections method, the new Nelder & Mead downhill simplex method), and technical aspects (back-end scripter structure, graphical user interface). While PHOEBE retains 100% WD compatibility, its add-ons are a powerful way to enhance WD by encompassing even more physics and solution reliability. The operability of all these extensions is demonstrated on a synthetic main-sequence test binary; applications to real data will be published in follow-up papers. PHOEBE is released under the GNU General Public License, which guarantees it to be free and open to anyone interested in joining in on future development.

  1. An automated search of O'Connell effect for Large Numbers of Eclipsing Binaries

    NASA Astrophysics Data System (ADS)

    Papageorgiou, A.; Kleftogiannis, G.; Christopoulou, P. E.

    2013-09-01

    The O'Connell effect in eclipsing binary systems (unequally high maxima) has stood for many decades as one of the most perplexing challenges in binary studies. So far, this simple asymmetry has not been convincingly explained, but most theories attribute the effect to dynamic phenomena such as migrating star-spots or swirling circumstellar gas and dust. Nevertheless there has been no clear demonstration of a correlation between the assumptions of any one theory and the morphology of physical parameters of binary systems that exhibit O'Connell effect. We have developed an automated program that characterizes the morphology of light curves by depth of both minima, height of both maxima and curvature outside the eclipses. In terms of programming it is being developed in FORTRAN and PYTHON. This project results from realization of two needs, both related to recent discoveries of large number of contact binaries. Thus the first need is of a simple method to obtain essential parameters for these systems, without the necessity of full light-curve synthesis solution. The second is a statistical one: we would like to extract information from light curves with the use of coefficients that describe the asymmetry in the light curve maxima and the overall shape in the growing observational data of eclipsing binaries (OGLE, ASAS, KEPLER, GAIA). Before applying the automated program several complications must be addressed, as eccentricity, quality of data with many outlying points, limitations to the classification method already applied.

  2. Eclipsing binary stars in the Large and Small Magellanic Clouds from the MACHO project: The Sample

    SciTech Connect

    Faccioli, L; Alcock, C; Cook, K; Prochter, G; Protopapas, P; Syphers, D

    2007-03-29

    We present a new sample of 4634 eclipsing binary stars in the Large Magellanic Cloud (LMC), expanding on a previous sample of 611 objects and a new sample of 1509 eclipsing binary stars in the Small Magellanic Cloud (SMC), that were identified in the light curve database of the MACHO project. We perform a cross correlation with the OGLE-II LMC sample, finding 1236 matches. A cross correlation with the OGLE-II SMC sample finds 698 matches. We then compare the LMC subsamples corresponding to center and the periphery of the LMC and find only minor differences between the two populations. These samples are sufficiently large and complete that statistical studies of the binary star populations are possible.

  3. VizieR Online Data Catalog: Kepler eclipsing binary stars. V. (Conroy+, 2014)

    NASA Astrophysics Data System (ADS)

    Conroy, K. E.; Prsa, A.; Stassun, K. G.; Bloemen, S.; Parvizi, M.; Quarles, B.; Boyajian, T.; Barclay, T.; Shporer, A.; Latham, D. W.; Abdul-Masih, M.

    2015-01-01

    Unlike the main Kepler mission that focused on a predetermined set of targets within the fixed field of view, the targets for each K2 campaign are solicited from the community, with ~10000 long-cadence (29.43 minute) and ~100 short-cadence (54.2s) targets selected for observations from each field (Howell et al., 2014PASP..126..398H). The Kepler Eclipsing Binary Working Group contributes a selection of science targets based on a cross-check of all objects in each K2 campaign field with available variable and binary star catalogs. One hundred and sixty four of 7757 targets selected for observation in campaign 0 and 49 of 21647 targets in campaign 1 were preidentified as eclipsing binaries (EBs). (4 data files).

  4. HII 2407: An Eclipsing Binary Revealed By K2 Observations of the Pleiades

    NASA Astrophysics Data System (ADS)

    David, Trevor J.; Stauffer, John; Hillenbrand, Lynne A.; Cody, Ann Marie; Conroy, Kyle; Stassun, Keivan G.; Pope, Benjamin; Aigrain, Suzanne; Gillen, Ed; Collier Cameron, Andrew; Barrado, David; Rebull, L. M.; Isaacson, Howard; Marcy, Geoffrey W.; Zhang, Celia; Riddle, Reed L.; Ziegler, Carl; Law, Nicholas M.; Baranec, Christoph

    2015-11-01

    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⊙ and R/R⊙ values with stellar evolutionary models. We also demonstrate that the system is likely 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.

  5. 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.

  6. Doubled-lined eclipsing binary system KIC~2306740 with pulsating component discovered from Kepler space photometry

    NASA Astrophysics Data System (ADS)

    Yakut, Kadri

    2015-08-01

    We present a detailed study of KIC 2306740, an eccentric double-lined eclipsing binary system with a pulsating component.Archive Kepler satellite data were combined with newly obtained spectroscopic data with 4.2\\,m William Herschel Telescope(WHT). This allowed us to determine rather precise orbital and physical parameters of this long period, slightly eccentric, pulsating binary system. Duplicity effects are extracted from the light curve in order to estimate pulsation frequencies from the residuals.We modelled the detached binary system assuming non-conservative evolution models with the Cambridge STARS(TWIN) code.

  7. Spectral variations in the low-mass X-ray binary 4U 0614+09

    NASA Technical Reports Server (NTRS)

    Singh, K. P.; Apparao, K. M. V.

    1994-01-01

    We report the X-ray spectra of a binary 4U 0614+09 observed with EXOSAT on five different occasions in 1984 and 1986. In four observations in 1984, the source intensity was 'low' compared to its intensity in the 1986 observation. The source was steady on timescales of 10 to 1000 s in each of the 1984 observations but highly variable during the 1986 variations. The best-fit spectral models for the continuum are a blackbody spectrum plus an emission from a Comptonized region. In addition, a component due to reflection from a cold disk around the source was needed as an absorbiton edge due to cold or ionized iron was seen near 7 keV with good significance in most of the spectra, particularly in the 'low' state. The relation of the hardness ratios with intensity follow the behavior seen in the 'Atoll' sources. We have studied the behavior of the hardness ratios with the variations in the parameters of the best-fit spectral models. Most of the variability is associated with the blackbody component thought to arise from the boundary layer on the surface of the neutron star. During the 'high' state in 1986, the blackbody temperature is higher, its size smaller, and its contribution significantly greater than in the 'low' state. The other notable difference between the two states is the lower opacity in the Comptonized region, and a significantly higher absorption in the 'high' state. A weak line emission (equivalent width = 10 to 40 eV) is detected during the 'high' state. The line energy lies between 6 and 7 keV wh ich implies its origin from ionized iron.

  8. Emission lines from X-ray-heated accretion disks in low-mass X-ray binaries

    NASA Technical Reports Server (NTRS)

    Ko, Yuan-Kuen; Kallman, Timothy R.

    1994-01-01

    We investigate the structure of accretion disks illuminated by X-rays from a central compact object in a binary system. X-rays can photoionize the upper atmosphere of the disk and form an accretion disk corona (ADC) where emission lines can form. We construct a model to calculate the vertical structure and the emission spectrum of the ADC with parameters appropriate to low-mass X-ray binaries. These models are made by nonlocal thermodynamic equilibrium calculations of ion and level populations and include a large number of atomic processes for 10 cosmically abundant elements. Transfer of radiation is treated by using the escape probability formalism. The vertical temperature profile of the ADC consists of a Compton-heated region and a mid-T zone where the temperature is approximately 10(exp 6) K. A thermal instability occurs close to the disk photosphere and causes the temperature of the ADC to drop abruptly from 10(exp 6) K to several times 10(exp 4) K. The emission spectrum in the optical, ultraviolet, extreme ultraviolet, and X-ray range is discussed and compared with the observations.

  9. Big Game Hunting in the Andromeda Galaxy: identifiying and weighing black holes in low mass X-ray Binaries

    NASA Astrophysics Data System (ADS)

    Barnard, R.

    2004-07-01

    We have devised a new technique for identifying stellar mass black holes in low mass X-ray binaries, and have applied it to XMM-Newton observations of two X-ray sources in M31. In particular we search for low accretion rate power density spectra; these are very similar for all LMXB, whether the primary is a black hole or a neutron star. Galactic neutron star LMXB exhibit these distinctive PDS at very low luminosities ( ˜ 1036 erg s-1) while black hole LMXB can exhibit them at luminosities > 1038 erg s-1! Following the work of van der Klis (1994), we assume a maximum accretion rate (as a fraction of the Eddington limit) for low accretion rate PDS that is constant for all LMXB, and obtain an empirical value of ˜ 10% Eddington. We have so far discovered two candidate black hole binaries in M31, exhibiting low accretion rate PDS at up to 3×1038 and 5×1037 erg s-1. If we assume that they are at <10% Eddington, they have minimum masses of 20 and 4 M⊙ respectively. Furthermore, any LMXB exhibiting a low accretion rate power density spectrum at a luminosity > 5×1037 erg s-1 is likely to have a black hole primary.

  10. Study of magnetic field effects for accretions with highly magnetized neutron stars in low mass X-ray binaries

    NASA Astrophysics Data System (ADS)

    Sasano, Makoto; Enoto, Teruaki; Makishima, Kazuo; Sakurai, Soki

    Neutron stars (NSs) in high-mass X-ray binaries (HMXBs), namely those with massive privary stars, generally have strong magnetic fields (˜10 (12) G). In contrast, those in typical low mass binary systems (LMXBs) are weakly magnetized (˜10 (9-10) G). This clear difference in the magnetic field strength is considered to be primarily responsible for the systematic differences in X-ray properties between NSs in HMXBs and those in LMXBs. However, these can also be possible contributions from their accretion-scheme differences, i.e., wind capture in HMXBs and disk accretion in LMXBs. To separate these two effects, we may utilize a few highly-magnetized NSs in LMXBs, including Her X-1, GX 1+4, 4U 1626-67, and a recently recognized object 4U 1822-37 (Sasano et al. PASJ in press, arXiv:1311.4618). In this study, we compare spectral and timing properties of these exceptional strong-field NSs, with those of more typical objects in LMXBs an HMXBs. Their properties that are common with typical HMXBs can be regarded as a signature of strong magnetic fields while those shared by typical LMXBs can be attributed to the disk-fed accretion geometry.

  11. ellc: A fast, flexible light curve model for detached eclipsing binary stars and transiting exoplanets

    NASA Astrophysics Data System (ADS)

    Maxted, P. F. L.

    2016-06-01

    Context. Very high quality light curves are now available for thousands of detached eclipsing binary stars and transiting exoplanet systems as a result of surveys for transiting exoplanets and other large-scale photometric surveys. Aims: I have developed a binary star model (ellc) that can be used to analyse the light curves of detached eclipsing binary stars and transiting exoplanet systems that is fast and accurate, and that can include the effects of star spots, Doppler boosting and light-travel time within binaries with eccentric orbits. Methods: The model represents the stars as triaxial ellipsoids. The apparent flux from the binary is calculated using Gauss-Legendre integration over the ellipses that are the projection of these ellipsoids on the sky. The model can also be used to calculate the flux-weighted radial velocity of the stars during an eclipse (Rossiter-McLaghlin effect). The main features of the model have been tested by comparison to observed data and other light curve models. Results: The model is found to be accurate enough to analyse the very high quality photometry that is now available from space-spaced instruments, flexible enough to model a wide range of eclipsing binary stars and extrasolar planetary systems, and fast enough to enable the use of modern Monte Carlo methods for data analysis and model testing. The software package is 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/591/A111

  12. 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.

  13. 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.

  14. KIC 9851142: A binary star with total eclipses and γ Dor pulsations

    NASA Astrophysics Data System (ADS)

    Çakırlı, Ö.

    2015-07-01

    KIC 9851142 (V2094 Cyg, HD 188854) is an eccentric eclipsing binary with an orbital period of Porb = 8.4854 d, exhibiting millimagnitude (mmag) amplitude pulsations on time scales of a few days. I present the results of the analysis of high-resolution spectroscopic data and Kepler long and short cadence photometry. The iterative combination of spectral classification by atmospheric analysis, radial velocity and eclipse timing variation studies, separation of pulsational features of the light curve, and binary light curve analysis led to the accurate determination of the fundamental stellar parameters and the comparison with evolutionary models strict constraints on the system age. I found that the binary is composed of two main sequence stars with an age of 0.75 ± 0.21 Gyr, having masses, radii and temperatures of M1 = 1.79 ± 0.11 M⊙ , R1 = 2.47 ± 0.07R⊙,Teff1 = 7250 ± 480 K for the primary, and M2 = 0.83 ± 0.12M⊙ , R2 = 0.67 ± 0.05R⊙,Teff2 = 5050 ± 650 K for the secondary. Multiple frequency analyses techniques were applied to the light residuals after subtracting the synthetic eclipsing curve from the Kepler data. This revealed that the primary component of KIC 9851142 is a γ Dor type pulsating star, exhibiting five pulsation frequencies in the range of 0.6-1.95 d-1 with amplitudes of 0.29-6.72 mmag and pulsation constants of 0.24-0.27 d. The analysis of the eclipse timing variations revealed preliminary apsidal motion with a period of Papseobs = 240 ± 29 y. Only six eclipsing binaries have been known to contain γ Dor pulsating components and, therefore, KIC 9851142 will be an important test-bed for examining these exceptional and interesting objects.

  15. Fundamental Parameters of Eclipsing Binaries in the Kepler Field of View

    NASA Astrophysics Data System (ADS)

    Matson, Rachel A.

    2016-01-01

    Accurate knowledge of stellar parameters such as mass, radius, composition, and age inform our understanding of stellar evolution and constrain theoretical models. Binaries and, in particular, eclipsing binaries make it possible to directly measure these parameters without reliance on models or scaling relations. In my dissertation I derive fundamental parameters of stars in close binary systems with and without (detected) tertiary companions and obtain accurate masses and radii of the components to compare with evolutionary models. Radial velocities and spectroscopic orbits are derived from optical spectra, while Doppler tomography is used to determine effective temperatures, projected rotational velocities, and metallicities for each component of the binary. These parameters are then combined with Kepler photometry to obtain accurate masses and radii through light curve and radial velocity fitting with the binary modeling software ELC. Here, I present spectroscopic orbits, atmospheric parameters, and estimated masses for 41 eclipsing binaries (including seven with tertiary companions) that were observed with Kepler and have periods less then six days. Further analysis, including binary modeling and comparison with evolutionary models is shown for a sub-sample of these stars.

  16. THE ANTICORRELATED NATURE OF THE PRIMARY AND SECONDARY ECLIPSE TIMING VARIATIONS FOR THE KEPLER CONTACT BINARIES

    SciTech Connect

    Tran, K.; Rappaport, S.; Levine, A.; Borkovits, T.; Csizmadia, Sz.; Kalomeni, B. E-mail: aml@space.mit.edu E-mail: szilard.csizmadia@dlr.de

    2013-09-01

    We report a study of the eclipse timing variations in contact binary systems, using long-cadence lightcurves from the Kepler archive. As a first step, observed minus calculated (O - C) curves were produced for both the primary and secondary eclipses of some 2000 Kepler binaries. We find {approx}390 short-period binaries with O - C curves that exhibit (1) random walk-like variations or quasi-periodicities, with typical amplitudes of {+-}200-300 s, and (2) anticorrelations between the primary and secondary eclipse timing variations. We present a detailed analysis and results for 32 of these binaries with orbital periods in the range of 0.35 {+-} 0.05 days. The anticorrelations observed in their O - C curves cannot be explained by a model involving mass transfer, which, among other things, requires implausibly high rates of {approx}0.01 M{sub Sun} yr{sup -1}. We show that the anticorrelated behavior, the amplitude of the O - C delays, and the overall random walk-like behavior can be explained by the presence of a starspot that is continuously visible around the orbit and slowly changes its longitude on timescales of weeks to months. The quasi-periods of {approx}50-200 days observed in the O - C curves suggest values for k, the coefficient of the latitude dependence of the stellar differential rotation, of {approx}0.003-0.013.

  17. WOCS 40007: A DETACHED ECLIPSING BINARY NEAR THE TURNOFF OF THE OPEN CLUSTER NGC 6819

    SciTech Connect

    Jeffries, Mark W. Jr.; Sandquist, Eric L.; Orosz, Jerome A.; Brewer, Lauren N. E-mail: erics@mintaka.sdsu.edu E-mail: lbrewer@rohan.sdsu.edu; and others

    2013-09-15

    We analyze extensive BVR{sub c}I{sub c} time-series photometry and radial-velocity measurements for WOCS 40007 (Auner 259; KIC 5113053), a double-lined detached eclipsing binary and a member of the open cluster NGC 6819. Utilizing photometric observations from the 1 m telescope at Mount Laguna Observatory and spectra from the WIYN 3.5 m telescope, we measure precise and accurate masses ({approx}1.6% uncertainty) and radii ({approx}0.5%) for the binary components. In addition, we discover a third star orbiting the binary with a period greater than 3000 days using radial velocities and Kepler eclipse timings. Because the stars in the eclipsing binary are near the cluster turnoff, they are evolving rapidly in size and are sensitive to age. With a metallicity of [Fe/H] = +0.09 {+-} 0.03, we find the age of NGC 6819 to be about 2.4 Gyr from color-magnitude diagram (CMD) isochrone fitting and 3.1 {+-} 0.4 Gyr by analyzing the mass-radius (M-R) data for this binary. The M-R age is above previous determinations for this cluster, but consistent within 1{sigma} uncertainties. When the M-R data for the primary star of the additional cluster binary WOCS 23009 is included, the weighted age estimate drops to 2.5 {+-} 0.2 Gyr, with a systematic uncertainty of at least 0.2 Gyr. The age difference between our CMD and M-R findings may be the result of systematic error in the metallicity or helium abundance used in models, or due to slight radius inflation of one or both stars in the WOCS 40007 binary.

  18. SARA South Observations and Analysis of the Solar Type, Totally Eclipsing, Shallow Contact Binary, CW Sculptoris

    NASA Astrophysics Data System (ADS)

    Samec, Ronald G.; Norris, Cody; Van Hamme, Walter V.; Faulkner, Danny R.; Hill, Robert L.

    2016-01-01

    CW Scl is a Solar Type (T1 ~ 6000K) solar type eclipsing binary. It was observed in October and November, 2014 at Cerro Tololo in remote mode with the 0.6-m SARA South reflector. Three times of minimum light were calculated from our present observations, two primary and one secondary eclipses:HJD Min I = 2456939.60799±0.0002, 2456976.62450±0.0002,HJD Min II = 2456940.57227±0.0006.In addition, six observations at minima were determined from archived All Sky Automated Survey Data:HJD Min I = 2452177.603, 2452466.793, 2454404.752,HJD Min II = 2453647.652, 2454669.843, 2455101.701.The following quadratic ephemerides was determined from all available times of minimum light:JD Hel Min I=2452940.67733±0.0003d + 0.3855865917±0.00031 X E+0.000000000114±0.000000000002 X E2A BVRcIc simultaneous Wilson-Devinney Program (W-D) solution reveals that the system has a mass ratio of ~0.39, and a component temperature difference of ~200 K. A Binary Maker fitted cool spot was eliminatedby WD Synthetic Light Curve Computations. The Roche Lobe fill-out is only 7/%. The inclination is ~86°. An eclipse duration of 19.5 minutes was determined for the primary eclipse. Additional and more detailedinformation is given in this report.

  19. New Developments in Eclipsing Binary Light Curve Modeling

    NASA Astrophysics Data System (ADS)

    Milone, E. F.; Stagg, C. R.

    1994-03-01

    The light curve modeling of binary stars has continued to evolve since its founding by Henry Norris Russell (see Russell and Merrill 1952 and citations therein) nearly a century ago, accelerated in the 1950s by Kopal's introduction of Roche geometry into models and by the development of synthetic light curve computer code in the 1970's. Improved physics and the use of more kinds of observational input are providing another round of important advances that promise to enlarge our knowledge of both binary stars and ensembles containing them. Here we discuss the newer horizons of light curve modeling and the steps being taken toward them.

  20. AbsParEB and InPeVEB: Software for the Calculation of Absolute and Orbital Period Changes Parameters of Eclipsing Binaries

    NASA Astrophysics Data System (ADS)

    Liakos, A.

    2015-07-01

    The software ABSPAREB (Absolute Parameters of Eclipsing Binaries) calculates the absolute parameters and their formal errors for three different modes: a) double-lined spectroscopic eclipsing binary, b) single-lined spectroscopic eclipsing binary, and c) for an eclipsing binary for which there is no spectroscopic information. In addition, the positions of the binary's members on the mass-radius and color-magnitude diagrams can be also plotted. INPEVEB (Interpretation of Period Variations of Eclipsing Binaries) calculates the parameters as well as their formal errors for several orbital period modulating mechanisms in eclipsing binaries (i.e., LITE, the Applegate mechanism, mass transfer/loss, apsidal motion, magnetic braking) using from an analysis of their O-C diagrams. Both programs are available online (free of charge) in Graphical User Interface form and were written in PYTHON.

  1. Application of the Direct Distance Estimation procedure to eclipsing binaries in star clusters

    NASA Astrophysics Data System (ADS)

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

    2013-02-01

    We alert the community to a paradigm method to calibrate a range of standard candles by means of well-calibrated photometry of eclipsing binaries in star clusters. In particular, we re-examine systems studied as part of our Binaries-in-Clusters program, and previously analyzed with earlier versions of the Wilson-Devinney light-curve modeling program. We make use of the 2010 version of this program, which incorporates a procedure to estimate the distance to an eclipsing system directly, as a system parameter, and is thus dependent on the data and analysis model alone. As such, the derived distance is accorded a standard error, independent of any additional assumptions or approximations that such analyses conventionally require.

  2. Discovery of a Long-Period Eclipsing Binary in M67

    NASA Astrophysics Data System (ADS)

    Sandquist, Eric L.; Latham, David W.; Mathieu, Robert D.; Vanderburg, Andrew; Brown, Timothy M.; M67 K2 Team

    2016-06-01

    We announce the detection of an eclipsing binary (WOCS 12009 / Sanders 1247) near the turnoff of the heavily-studied old open cluster M67 using K2 Campaign 5 data. The object was previously known to be a double-lined spectroscopic binary, and the orbit period (69.75 d) agrees with the photometric period. We present a preliminary analysis of the K2 photometry, multi-band ground-based photometry of the eclipses, and extensive radial velocity observations of the two stars. Precise measurements of the pair will begin to provide mass and radius scales for cluster stars, and will constrain the age of this iconic open cluster.We gratefully acknowledge support from NASA through grant NNX15AW24A to R.D.M.

  3. The Cepheid in the eclipsing binary system OGLE-LMC-CEP1812 is a stellar merger

    NASA Astrophysics Data System (ADS)

    Neilson, Hilding; Ignace, Richard

    2014-06-01

    Classical Cepheids and eclipsing binary systems are powerful probes for measuring stellar fundamental parameters and constraining stellar astrophysics. A Cepheid in an eclipsing binary system is even more powerful, constraining stellar physics, the distance scale and the Cepheid mass discrepancy. However, these systems are rare, only three have been discovered. One of these, OGLE-LMC-CEP1812, presents a new mystery: where the Cepheid component appears to be younger than its red giant companion. In this work, we present stellar evolution models and show that the Cepheid is actually product of a stellar merger during main sequence evolution that causes the Cepheid to be a rejuvenated star. This result raises new questions into the evolution of Cepheids and their connections to smaller-mass anomalous Cepheids.

  4. Adaptive Optics imaging of VHS 1256-1257: A Low Mass Companion to a Brown Dwarf Binary System

    NASA Astrophysics Data System (ADS)

    Stone, Jordan M.; Skemer, Andrew J.; Kratter, Kaitlin M.; Dupuy, Trent J.; Close, Laird M.; Eisner, Josh A.; Fortney, Jonathan J.; Hinz, Philip M.; Males, Jared R.; Morley, Caroline V.; Morzinski, Katie M.; Ward-Duong, Kimberly

    2016-02-01

    Recently, Gauza et al. reported the discovery of a companion to the late M-dwarf, VHS J125601.92-125723.9 (VHS 1256-1257). The companion’s absolute photometry suggests its mass and atmosphere are similar to the HR 8799 planets. However, as a wide companion to a late-type star, it is more accessible to spectroscopic characterization. We discovered that the primary of this system is an equal-magnitude binary. For an age ˜300 Myr the A and B components each have a mass of {64.6}-2.0+0.8 {M}{Jup}, and the b component has a mass of {11.2}-1.8+9.7, making VHS 1256-1257 only the third brown dwarf triple system. There exists some tension between the spectrophotometric distance of 17.2 ± 2.6 pc and the parallax distance of 12.7 ± 1.0 pc. At 12.7 pc VHS 1256-1257 A and B would be the faintest known M7.5 objects, and are even faint outliers among M8 types. If the larger spectrophotmetric distance is more accurate than the parallax, then the mass of each component increases. In particular, the mass of the b component increases well above the deuterium burning limit to ˜ 35 {M}{Jup} and the mass of each binary component increases to {73}-17+20 {M}{Jup}. At 17.1 pc, the UVW kinematics of the system are consistent with membership in the AB Dor moving group. The architecture of the system resembles a hierarchical stellar multiple suggesting it formed via an extension of the star formation process to low masses. Continued astrometric monitoring will resolve this distance uncertainty and will provide dynamical masses for a new benchmark system.

  5. Simultaneous radio and X-ray observations of Galactic Centre low-mass X-ray binaries

    NASA Astrophysics Data System (ADS)

    Berendsen, Stephan G. H.; Fender, Robert; Kuulkers, Erik; Heise, J.; van der Klis, M.

    2000-10-01

    We have performed simultaneous X-ray and radio observations of 13 Galactic Centre low-mass X-ray binaries in 1998 April using the Wide Field Cameras on board BeppoSAX and the Australia Telescope Compact Array, the latter simultaneously at 4.8 and 8.64GHz. We detect two Z sources, GX 17+2 and GX 5-1, and the unusual `hybrid' source GX 13+1. Upper limits, which are significantly deeper than previous non-detections, are placed on the radio emission from two more Z sources and seven atoll sources. Hardness-intensity diagrams constructed from the Wide Field Camera data reveal GX 17+2 and GX 5-1 to have been on the lower part of the horizontal branch and/or the upper part of the normal branch at the time of the observations, and the two non-detected Z sources, GX 340+0 and GX 349+2, to have been on the lower part of the normal branch. This is consistent with the previous empirically determined relation between radio and X-ray emission from Z sources, in which radio emission is strongest on the horizontal branch and weakest on the flaring branch. For the first time we have information on the X-ray state of atoll sources, which are clearly radio-quiet relative to the Z sources, during periods of observed radio upper limits. We place limits on the linear polarization from the three detected sources, and use accurate radio astrometry of GX 17+2 to confirm that it is probably not associated with the optical star NP Ser. Additionally we place strong upper limits on the radio emission from the X-ray binary 2S 0921-630, disagreeing with suggestions that it is a Z-source viewed edge-on.

  6. Common Patterns in the Evolution between the Luminous Neutron Star Low-Mass X-ray Binary Subclasses

    NASA Astrophysics Data System (ADS)

    Fridriksson, Joel K.; Homan, Jeroen; Remillard, Ronald A.

    2015-08-01

    The X-ray transient XTE J1701-462 was the first source observed to evolve through all known subclasses of low-magnetic-field neutron star low-mass X-ray binaries (NS-LMXBs), as a result of large changes in its mass accretion rate. To investigate to what extent similar evolution is seen in other NS-LMXBs we have performed a detailed study of the color-color and hardness-intensity diagrams (CDs and HIDs) of Cyg X-2, Cir X-1, and GX 13+1—three luminous X-ray binaries, containing weakly magnetized neutron stars, known to exhibit strong secular changes in their CD/HID tracks. Using the full set of Rossi X-ray Timing Explorer Proportional Counter Array data collected for the sources over the 16 year duration of the mission, we show that Cyg X-2 and Cir X-1 display CD/HID evolution with close similarities to XTE J1701-462. Although GX 13+1 shows behavior that is in some ways unique, it also exhibits similarities to XTE J1701-462, and we conclude that its overall CD/HID properties strongly indicate that it should be classified as a Z source, rather than as an atoll source. We conjecture that the secular evolution of Cyg X-2, Cir X-1, and GX 13+1—illustrated by sequences of CD/HID tracks we construct—arises from changes in the mass accretion rate. Our results strengthen previous suggestions that within single sources Cyg-like Z source behavior takes place at higher luminosities and mass accretion rates than Sco-like Z behavior, and lend support to the notion that the mass accretion rate is the primary physical parameter distinguishing the various NS-LMXB subclasses.

  7. An eclipsing double-line spectroscopic binary at the stellar/substellar boundary in the Upper Scorpius OB association

    NASA Astrophysics Data System (ADS)

    Lodieu, N.; Alonso, R.; González Hernández, J. I.; Sanchis-Ojeda, R.; Narita, N.; Kawashima, Y.; Kawauchi, K.; Suárez Mascareño, A.; Deeg, H.; Prieto Arranz, J.; Rebolo, R.; Pallé, E.; Béjar, V. J. S.; Ferragamo, A.; Rubiño-Martín, J. A.

    2015-12-01

    Aims: We aim at constraining evolutionary models at low mass and young ages by identifying interesting transiting system members of the nearest OB association to the Sun, Upper Scorpius (USco), which has been targeted by the Kepler mission. Methods: We produced light curves for M-dwarf members of the USco region that has been surveyed during the second campaign of the Kepler K2 mission. We identified by eye a transiting system, USco J161630.68-251220.1 (=EPIC 203710387) with a combined spectral type of M5.25, whose photometric, astrometric, and spectroscopic properties makes it a member of USco. We conducted an extensive photometric and spectroscopic follow-up of this transiting system with a suite of telescopes and instruments to characterise the properties of each component of the system. Results: We calculated a transit duration of about 2.42 h that occurs every 2.88 days with a slight difference in transit depth and phase between the two components. We estimated a mass ratio of 0.922 ± 0.015 from the semi-amplitudes of the radial velocity curves for each component. We derived masses of 0.091 ± 0.005M⊙ and 0.084 ± 0.004M⊙, radii of 0.388 ± 0.008R⊙ and 0.380 ± 0.008R⊙, luminosities of log (L/L⊙) = -2.020-0.121+0.099 dex and -2.032-0.121+0.099 dex, and effective temperatures of 2901-172+199 K and 2908-172+199 K for the primary and secondary, respectively. Conclusions: We present a complete photometric and radial velocity characterisation of the least massive double-line eclipsing binary system in the young USco association with two components close to the stellar/substellar limit. This system falls in a gap between the least massive eclipsing binaries in the low-mass and substellar regimes at young ages and represents an important addition to constraining evolutionary models at young ages. Based on observations made with telescopes (GTC, WHT) installed in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofísica de

  8. Period Studies of 79 Eccentric Eclipsing Binaries in the Large Magellanic Cloud

    NASA Astrophysics Data System (ADS)

    Hong, K.; Kang, Y. W.; Lee, C.-U.

    2014-08-01

    We present period studies for seventy-nine eclipsing binaries in the Large Magellanic Cloud. New times of minimum light were derived from the data obtained by the EROS, OGLE-II and OGLE-III surveys. Nineteen stars of the seventy-nine stars show period variation were confirmed. All of the systems were studied by means of an O-C diagram analyses. Nine systems show apsidal motion, six systems show parabola, and four systems show sinusoidal period variations, respectively.

  9. 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.

  10. The tormented quiescence of the low mass X-ray binaries Cen X-4 and V404 Cyg

    NASA Astrophysics Data System (ADS)

    Bernardini, F.; Cackett, E.

    2014-07-01

    The majority of low mass X-ray binaries (LMXBs) spend the bulk of their time in the quiescent state, where their X-ray emission is a tiny fraction of the Eddington luminosity. However, the physical mechanisms involved during quiescence are still debated. So far, a unifying scenario that can systematically match the spectral energy distribution from optical up to the X-ray emission of both NS and BH quiescent LMXBs, is still missing. Moreover, an increasing number of LMXBs display variability in quiescence, the origin of which is still unclear. Residual accretion at very low Eddington luminosity rates could play an important role, however, there has lacked clear observational constraints on such processes. With the main goal of unveiling the nature of the quiescent variability in LMXBs we planned a unique study of the two best targets: the NS Cen X-4 and the BH V404 Cyg. We conducted a multi-wavelength (optical, ultraviolet, and X-ray) long-term monitoring (months) of the two sources on a daily basis. This allowed us for the very first time to accurately characterize their variability properties, find strong evidence of UV/X-ray correlation in the emission from Cen X-4, and show that both sources are very likely accreting also in quiescence.

  11. Energy dependence of normal branch quasi-periodic intensity oscillations in low-mass X-ray binaries

    NASA Astrophysics Data System (ADS)

    Miller, Guy S.; Lamb, Frederick K.

    1992-04-01

    The properties of the approximately 6 Hz quasi-periodic X-ray intensity oscillations observed in the low-mass X-ray binary Cyg X-2 when it is on the normal spectral branch are shown to be consistent with a model in which photons from a central source with a fixed spectrum are Comptonized by an oscillating radial inflow. As the electron scattering optical depth of the flow varies, the spectrum of the escaping X-rays appears to rotate about a pivot energy that depends mainly on the electron temperature in the flow. The temperature derived from the observed energy dependence of the Cyg X-2 normal branch oscillations is approximately 1 keV, in good agreement with the estimated Compton temperature of its X-ray spectrum. The mean optical depth tau of the Comptonizing flow is inferred to be about 10, while the change in tau over an oscillation is estimated to be about 1; both values are in good agreement with radiation hydrodcode simulations of the radial flow.

  12. Energy dependence of normal branch quasi-periodic intensity oscillations in low-mass X-ray binaries

    NASA Technical Reports Server (NTRS)

    Miller, Guy S.; Lamb, Frederick K.

    1992-01-01

    The properties of the approximately 6 Hz quasi-periodic X-ray intensity oscillations observed in the low-mass X-ray binary Cyg X-2 when it is on the normal spectral branch are shown to be consistent with a model in which photons from a central source with a fixed spectrum are Comptonized by an oscillating radial inflow. As the electron scattering optical depth of the flow varies, the spectrum of the escaping X-rays appears to rotate about a pivot energy that depends mainly on the electron temperature in the flow. The temperature derived from the observed energy dependence of the Cyg X-2 normal branch oscillations is approximately 1 keV, in good agreement with the estimated Compton temperature of its X-ray spectrum. The mean optical depth tau of the Comptonizing flow is inferred to be about 10, while the change in tau over an oscillation is estimated to be about 1; both values are in good agreement with radiation hydrodcode simulations of the radial flow.

  13. TRANSIENT LOW-MASS X-RAY BINARY POPULATIONS IN ELLIPTICAL GALAXIES NGC 3379 AND NGC 4278

    SciTech Connect

    Fragos, T.; Kalogera, V.; Willems, B. E-mail: vicky@northwestern.edu

    2009-09-10

    We propose a physically motivated and self-consistent prescription for the modeling of transient neutron star low-mass X-ray binary (LMXB) properties, such as duty cycle (DC), outburst duration, and recurrence time. We apply this prescription to the population synthesis models of field LMXBs presented by Fragos et al., and compare the transient LMXB population to the Chandra X-ray survey of the two elliptical galaxies NGC 3379 and NGC 4278, which revealed several transient sources. We are able to exclude models with a constant DC for all transient systems, while models with a variable DC based on the properties of each system are consistent with the observed transient populations. We predict that the majority of the observed transient sources in these two galaxies are LMXBs with red giant donors. Finally, our comparison suggests that transient LMXBs are very rare in globular clusters (GCs), and thus the number of identified transient LMXBs may be used as a tracer of the relative contribution of field and GC LMXB populations.

  14. The Discovery of a Second Luminous Low Mass X-Ray Binary System in the Globular Cluster M15

    NASA Technical Reports Server (NTRS)

    White, Nicholas E.; Angelini, Lorella

    2001-01-01

    Using the Chandra X-ray Observatory we have discovered a second bright X-ray source in the globular cluster M15 that is 2.7" to the west of AC211, the previously known low mass X-ray binary (LMXB) in this system. Prior to the 0.5" imaging capability of Chandra this second source could not have been resolved from AC211. The luminosity and spectrum of this new source, which we call M15-X2, are consistent with it also being a LMXB system. This is the first time that two LMXBs have been seen to be simultaneously active in a globular cluster. The new source, M15-X2, is coincident with a 18th U magnitude very blue star. The discovery of a second LMXB in M15 clears up a long standing puzzle where the X-ray and optical properties of AC211 appear consistent with the central source being hidden behind an accretion disk corona, and yet also showed a luminous X-ray burst suggesting the neutron star is directly visible. This discovery suggests instead that the X-ray burst did not come from AC211, but rather from the newly discovered X-ray source. We discuss the implications of this discovery for X-ray observations of globular clusters in nearby galaxies.

  15. A Suzaku observation of the low-mass X-ray binary GS 1826-238 in the hard state

    NASA Astrophysics Data System (ADS)

    Ono, Ko; Sakurai, Soki; Zhang, Zhongli; Nakazawa, Kazuhiro; Makishima, Kazuo

    2016-06-01

    The neutron star low-mass X-ray binary GS 1826-238 was observed with Suzaku on 2009 October 21, for a total exposure of 1030 ks. Except for the type I bursts, the source intensity was constant within ˜10%. Combining the Suzaku XIS, HXD-PIN, and HXD-GSO data, burst-removed persistent emission was detected over the 0.8-100 keV range, at an unabsorbed flux of 2.6 × 10-9 erg s-1 cm-2. Although the implied 0.8-100 keV luminosity, 1.5 × 1037 erg s-1 (assuming a distance of 7 kpc), is relatively high, the observed hard spectrum confirms that the source was in the hard state. The spectrum was successfully explained by an emission from a soft standard accretion disk partially Comptonized by a hot electron cloud, and a blackbody emission Comptonized by another hotter electron cloud. These results are compared with those from previous studies, including those on the same source by Thompson et al. (2005, ApJ, 634, 1261) and Cocchi, Farinelli, and Paizis (2011, A&A, 529, A155), as well as that of Aql X-1 in the hard state obtained with Suzaku (Sakurai et al. 2014, PASJ, 66, 10).

  16. The magnetohydrodynamical model of kilohertz quasi-periodic oscillations in neutron star low-mass X-ray binaries (II)

    SciTech Connect

    Shi, Chang-Sheng; Zhang, Shuang-Nan; Li, Xiang-Dong

    2014-08-10

    We study the kilohertz quasi-periodic oscillations (kHz QPOs) in neutron star low-mass X-ray binaries (LMXBs) with a new magnetohydrodynamics (MHD) model, in which the compressed magnetosphere is considered. The previous MHD model is reexamined and the relation between the frequencies of the kHz QPOs and the accretion rate in LMXBs is obtained. Our result agrees with the observations of six sources (4U 0614+09, 4U 1636-53, 4U 1608-52, 4U 1915-15, 4U 1728-34, and XTE 1807-294) with measured spins. In this model, the kHz QPOs originate from the MHD waves in the compressed magnetosphere. The single kHz QPOs and twin kHz QPOs are produced in two different parts of the accretion disk and the boundary is close to the corotation radius. The lower QPO frequency in a frequency-accretion rate diagram is cut off at a low accretion rate and the twin kHz QPOs encounter a top ceiling at a high accretion rate due to the restriction of the innermost stable circular orbit.

  17. A COMPARISON OF BROAD IRON EMISSION LINES IN ARCHIVAL DATA OF NEUTRON STAR LOW-MASS X-RAY BINARIES

    SciTech Connect

    Cackett, Edward M.; Miller, Jon M.; Reis, Rubens C.; Fabian, Andrew C.; Barret, Didier

    2012-08-10

    Relativistic X-ray disklines have been found in multiple neutron star low-mass X-ray binaries, in close analogy with black holes across the mass scale. These lines have tremendous diagnostic power and have been used to constrain stellar radii and magnetic fields, often finding values that are consistent with independent timing techniques. Here, we compare CCD-based data from Suzaku with Fe K line profiles from archival data taken with gas-based spectrometers. In general, we find good consistency between the gas-based line profiles from EXOSAT, BeppoSAX, and RXTE and the CCD data from Suzaku, demonstrating that the broad profiles seen are intrinsic to the line and not broad due to instrumental issues. However, we do find that when fitting with a Gaussian line profile, the width of the Gaussian can depend on the continuum model in instruments with low spectral resolution, though when the different models fit equally well the line widths generally agree. We also demonstrate that three BeppoSAX observations show evidence for asymmetric lines, with a relativistic diskline model providing a significantly better fit than a Gaussian. We test this by using the posterior predictive p-value method, and bootstrapping of the spectra to show that such deviations from a Gaussian are unlikely to be observed by chance.

  18. Athena's Constraints on the Dense Matter Equation of State from Quiescent Low Mass X-ray Binaries

    NASA Astrophysics Data System (ADS)

    Guillot, Sebastien

    2016-07-01

    The study of neutron star quiescent low-mass X-ray binaries (qLMXBs) will address one of the science goals of the Athena X-ray observatory. The study of the soft X-ray thermal emission from the neutron star surface in qLMXBs is a crucial tool to place constrains on the dense matter equation of state and understand the interior structure of neutron stars. I will briefly review this method, its strengths and current weaknesses and limitations, as well as the current constraints on the equation of state from qLMXBs. The superior sensitivity of Athena will permit the acquisition of unprecedentedly high signal-to-noise spectra from these sources. It has been demonstrated that a single qLMXB, even with a high signal-to-noise spectrum, will not place useful constraints on the dense matter equation of state. However, a combination of qLMXB spectra has shown great promises of obtaining tight constraints on the equation of state. I will discuss the expected prospects for observations of qLMXBs and in particular, I will show that very tight constraints on the equation of state can be obtained from the observations of qLMXBs with the Athena X-ray observatory (even with a 10 % uncertainty on the flux calibration).

  19. CONTINUED COOLING OF THE CRUST IN THE NEUTRON STAR LOW-MASS X-RAY BINARY KS 1731-260

    SciTech Connect

    Cackett, Edward M.; Miller, Jon M.; Brown, Edward F.; Cumming, Andrew; Degenaar, Nathalie; Wijnands, Rudy

    2010-10-20

    Some neutron star low-mass X-ray binaries have very long outbursts (lasting several years) which can generate a significant amount of heat in the neutron star crust. After the system has returned to quiescence, the crust then thermally relaxes. This provides a rare opportunity to study the thermal properties of neutron star crusts, putting constraints on the thermal conductivity and hence the structure and composition of the crust. KS 1731-260 is one of only four systems where this crustal cooling has been observed. Here, we present a new Chandra observation of this source approximately eight years after the end of the last outburst and four years since the last observation. We find that the source has continued to cool, with the cooling curve displaying a simple power-law decay. This suggests that the crust has not fully thermally relaxed yet and may continue to cool further. A simple power-law decay is in contrast to theoretical cooling models of the crust, which predict that the crust should now have cooled to the same temperature as the neutron star core.

  20. The Magnetohydrodynamical Model of Kilohertz Quasi-periodic Oscillations in Neutron Star Low-mass X-Ray Binaries (II)

    NASA Astrophysics Data System (ADS)

    Shi, Chang-Sheng; Zhang, Shuang-Nan; Li, Xiang-Dong

    2014-08-01

    We study the kilohertz quasi-periodic oscillations (kHz QPOs) in neutron star low-mass X-ray binaries (LMXBs) with a new magnetohydrodynamics (MHD) model, in which the compressed magnetosphere is considered. The previous MHD model is reexamined and the relation between the frequencies of the kHz QPOs and the accretion rate in LMXBs is obtained. Our result agrees with the observations of six sources (4U 0614+09, 4U 1636-53, 4U 1608-52, 4U 1915-15, 4U 1728-34, and XTE 1807-294) with measured spins. In this model, the kHz QPOs originate from the MHD waves in the compressed magnetosphere. The single kHz QPOs and twin kHz QPOs are produced in two different parts of the accretion disk and the boundary is close to the corotation radius. The lower QPO frequency in a frequency-accretion rate diagram is cut off at a low accretion rate and the twin kHz QPOs encounter a top ceiling at a high accretion rate due to the restriction of the innermost stable circular orbit.

  1. Constraining the properties of neutron star crusts with the transient low-mass X-ray binary Aql X-1

    NASA Astrophysics Data System (ADS)

    Waterhouse, A. C.; Degenaar, N.; Wijnands, R.; Brown, E. F.; Miller, J. M.; Altamirano, D.; Linares, M.

    2016-03-01

    Aql X-1 is a prolific transient neutron star low-mass X-ray binary that exhibits an accretion outburst approximately once every year. Whether the thermal X-rays detected in intervening quiescent episodes are the result of cooling of the neutron star or due to continued low-level accretion remains unclear. In this work, we use Swift data obtained after the long and bright 2011 and 2013 outbursts, as well as the short and faint 2015 outburst, to investigate the hypothesis that cooling of the accretion-heated neutron star crust dominates the quiescent thermal emission in Aql X-1. We demonstrate that the X-ray light curves and measured neutron star surface temperatures are consistent with the expectations of the crust cooling paradigm. By using a thermal evolution code, we find that ≃1.2-3.2 MeV nucleon-1 of shallow heat release describes the observational data well, depending on the assumed mass-accretion rate and temperature of the stellar core. We find no evidence for varying strengths of this shallow heating after different outbursts, but this could be due to limitations of the data. We argue that monitoring Aql X-1 for up to ≃1 yr after future outbursts can be a powerful tool to break model degeneracies and solve open questions about the magnitude, depth, and origin of shallow heating in neutron star crusts.

  2. 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).

  3. A Photometric Study of the Eclipsing Binary Star V2790 Orionis

    NASA Astrophysics Data System (ADS)

    Michaels, E. J.

    2016-06-01

    Presented in this paper is the first precision set of multi-band light curves for the eclipsing binary star V2790 Ori. A new linear ephemeris gives an orbital period of 0.28784176 d. The light curves were analyzed with the Wilson-Devinney program to determine the best-fit stellar model. Star spots were required in the model to account for asymmetries in the light curves. The synthetic light curve solutions presented are consistent with a W-type contact binary.

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

    SciTech Connect

    Yang, Y.-G.; Dai, H.-F.; Yin, X.-G.; Yang, Y. E-mail: yangyg@chnu.edu.cn

    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 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 {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.

  5. Light Curve Solutions of Eclipsing Binaries in the Large Magellanic Cloud

    NASA Astrophysics Data System (ADS)

    Rawls, Meredith L.; Rao, M. S.

    2012-01-01

    We present model light curves for nine eclipsing binary stars in the Large Magellanic Cloud (LMC). These systems are detached binaries with nearly circular orbits, and were pseudorandomly selected from three of 21 LMC regions in the Optical Gravitational Lensing Experiment II (OGLE-II) survey. We make use of light curves, orbital periods, and binary classification as reported in Wyrzykowski et al. (2003). We present light curve solutions created with the software PHysics Of Eclipsing BinariEs (PHOEBE, Prsa & Zwitter 2005). Each solution has the best-fit mass ratio q, system inclination i, component temperatures T1 and T2, and modified Kopal potentials Ω1 and Ω2. PHOEBE employs a Nelder & Mead's Simplex fitting method that adjusts all the input parameters to find the best fit to the light curve. Many of the light curves have significant scatter, which can lead to multiple degenerate best-fit solutions, and we discuss what can be done in the future to refine our results, derive global stellar parameters, and place these nine systems in a larger context. We acknowledge the support of the International Research Experience for Students (IRES) program, which is sponsored by the NSF and administered by NSO/GONG.

  6. 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.

  7. UBVRI analysis of the totally eclipsing extreme mass ratio W UMa binary, GSC 3208 1986

    SciTech Connect

    Samec, R. G.; Kring, J. D.; Robb, Russell; Van Hamme, W.; Faulkner, D. R.

    2015-03-01

    GSC 3208 1986 is an NSVS and TYCHO binary, first observed from 1999 to 2000. It is a W UMa binary with a period of 0.405 days. The present observations were taken in 2012 September and are of high precision, averaging a standard deviation of better than 5 mmag. The amplitude of the light curve is very nearly 0.5 mag yet it undergoes total eclipses. Dominion Astrophysical Observatory spectra give an F3V type (T∼6900 K) for the system, the earliest of the extreme mass ratio W UMa binaries. The linear period determination of 0.4045672 days was calculated with the two sets of epochs available. An early NSVS light curve reveals that the period has been smoothly decreasing over its past 12,000 orbits. The binary may be undergoing sinusoidal oscillations due to the presence of a third body, possibly with a period of 23±3 years. The high inclination of 85° results in a long duration secondary total eclipse, lasting some 49.5 minutes. Findings indicate that GSC 3208 1986 is an immaculate extreme mass ratio, q(m{sub 2}/m{sub 1}) = 0.24, A-type W UMa binary.

  8. Astrometric confirmation of young low-mass binaries and multiple systems in the Chamaeleon star-forming regions

    NASA Astrophysics Data System (ADS)

    Vogt, N.; Schmidt, T. O. B.; Neuhäuser, R.; Bedalov, A.; Roell, T.; Seifahrt, A.; Mugrauer, M.

    2012-10-01

    masses twice as high as this value or more. Massive primary components appear to avoid the simultaneous formation of equal-mass secondary components, while extremely low-mass secondary components are hard to find for both high and low mass primaries owing to the much higher dynamic range and the faintness of the secondaries. Based on observations made with ESO telescopes at the Paranal Observatory under program IDs 076.C-0292(A), 078.C-0535(A), 080.C-0424(A), 082.C-0489(A), 084.C-0364(B), 086.C-0638(A) & 086.C-0600(B), the Hubble Space Telescope under program ID GO-8716 and data obtained from the ESO/ST-ECF Science Archive Facility from the Paranal Observatory under program IDs 075.C-0042(A), 076.C-0579(A), 278.C-5070(A) and from the Hubble Space Telescope under programme IDs SNAP-7387, GO-11164. Appendix A is available in electronic form at http://www.aanda.org

  9. Secondaries of eclipsing binaries. IV - The triple system Lambda Tauri

    NASA Technical Reports Server (NTRS)

    Fekel, F. C., Jr.; Tomkin, J.

    1982-01-01

    High signal-to-noise ratio Reticon observations of Lambda Tauri have been obtained along with high-quality orbital elements for both the primary and secondary of the eclipsing system. The velocity curve of the secondary is determined for the first time. The findings include: K(1) = 56.9 + or - 0.6 km/s, K(2 = 215.6 + or - 0.7 km/s, m(1) = 7.18 + or - 0.09 solar masses, and m(2) = 1.89 + or - 0.04 solar masses. The 33-day periodicity in the residuals is confirmed and is present in the secondary velocities as well as those of the primary, and can unambiguously be ascribed to orbital motion about a third body. The K and f(m) for the 33-day orbit are 10.1 + or - 0.7 km/s and 0.0034 + or - 0.0008 solar masses. The photometry shows that the orbits are coplanar to within seven degrees. The mass of the third body is 0.7 + or - 0.2 solar masses; it is most probably a K dwarf.

  10. ASCA Observation of MS 1603.6+2600 (=UW Coronae Borealis): A Dipping Low-Mass X-ray Binary in the Outer Halo?

    NASA Technical Reports Server (NTRS)

    Mukai, Koji; Smale, Alan; Stahle, Caroline K.; Schlegel, Eric M.; Wijnands, Rudy; White, Nicholas E. (Technical Monitor)

    2001-01-01

    MS 1603.6+2600 is a high-latitude X-ray binary with a 111 min orbital period, thought to be either an unusual cataclysmic variable or an unusual low-mass X-ray binary. In an ASCA observation in 1997 August, we find a burst whose light curve suggests a Type 1 (thermonuclear flash) origin. We also find an orbital X-ray modulation in MS 1603.6+2600, which is likely to be periodic dips, presumably due to azimuthal structure in the accretion disk. Both are consistent with this system being a normal low-mass X-ray binary harboring a neutron star, but at a great distance. We tentatively suggest that MS 1603.6+2600 is located in the outer halo of the Milky Way, perhaps associated with the globular cluster Palomar 14, 11 deg away from MS 1603.6+2600 on the sky at an estimated distance of 73.8 kpc.

  11. Spectroscopic Survey of Eclipsing Binaries with a Low-cost Echelle Spectrograph: Scientific Commissioning

    NASA Astrophysics Data System (ADS)

    Kozłowski, S. K.; Konacki, M.; Sybilski, P.; Ratajczak, M.; Pawłaszek, R. K.; Hełminiak, K. G.

    2016-07-01

    We present scientific results obtained with a recently commissioned échelle spectrograph on the 0.5 m Solaris-1 telescope in the South African Astronomical Observatory. BACHES is a low-cost slit échelle spectrograph that has a resolution of 21,000 at 5500 Å. The described setup is fully remotely operated and partly automated. Custom hardware components have been designed to allow both spectroscopic and photometric observations. The setup is controlled via dedicated software. The throughput of the system allows us to obtain spectra with an average signal-to-noise ratio of 22 at 6375 Å for a 30 minute exposure of a V = 10 mag target. The stability of the instrument is influenced mainly by the ambient temperature changes. We have obtained radial velocity (RV) rms values for a bright (V = 5.9 mag) spectroscopic binary as good as 0.59 and 1.34 km s‑1 for a V = 10.2 mag eclipsing binary. RV measurements have been combined with available photometric light curves. We present models of six eclipsing binary systems, and for previously known targets, we compare our results with those available in the literature. Masses of binary components have been determined with 3% errors for some targets. We confront our results with benchmark values based on measurements from the HARPS and UCLES spectrographs on 4 m class telescopes and find very good agreement. The described setup is very efficient and well suited for a spectroscopic survey. We can now spectroscopically characterize about 300 eclipsing binary stars per year up to 10.2 mag assuming typical weather conditions at SAAO without a single observing trip.

  12. CIRCUMSTELLAR ENVIRONMENT AND EFFECTIVE TEMPERATURE OF THE YOUNG SUBSTELLAR ECLIPSING BINARY 2MASS J05352184-0546085

    SciTech Connect

    Mohanty, Subhanjoy; Stassun, Keivan G.; Mathieu, Robert D.

    2009-05-20

    We present new Spitzer IRAC/PU/MIPS photometry from 3.6 to 24 {mu}m, and new Gemini GMOS photometry at 0.48 {mu}m, of the young brown dwarf eclipsing binary 2MASS J05352184-0546085, located in the Orion Nebula Cluster. No excess disk emission is detected. The measured fluxes at {lambda} {<=} 8 {mu}m are within 1{sigma} ({approx}<0.1 mJy) of a bare photosphere, and the 3{sigma} upper limit at 16 {mu}m is a mere 0.04 mJy above the bare photospheric level. Together with the known properties of the system, this implies the absence of optically thick disks around the individual components. It also implies that if any circumbinary disk is present, it must either be optically thin and extremely tenuous (10{sup -10} M {sub sun}) if it extends in to within {approx}0.1 AU of the binary (the approximate tidal truncation radius), or it must be optically thick with a large inner hole, >0.6-10 AU in radius depending on degree of flaring. The consequence in all cases is that disk accretion is likely to be negligible or absent. This supports the recent proposal that the strong H{alpha} emission in the primary (more massive) brown dwarf results from chromospheric activity, and thereby bolsters the hypothesis that the surprising T {sub eff} inversion observed between the components is due to strong magnetic fields on the primary. Our data also set constraints on the T {sub eff} of the components independent of spectral type, and thereby on models of the aforementioned magnetic field effects. We discuss the consequences for the derived fundamental properties of young brown dwarfs and very low mass stars in general. Specifically, if very active isolated young brown dwarfs and very low mass stars suffer the same activity/field related effects as the 2M0535-05 primary, the low-mass stellar/substellar initial mass function currently derived from standard evolutionary tracks may be substantially in error.

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

    SciTech Connect

    Kato, Mariko; Hachisu, Izumi; Mikolajewska, Joanna

    2013-01-20

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

  14. A period study and revised photometric model for the eclipsing binary ZZ Cyg

    NASA Astrophysics Data System (ADS)

    Yang, Yuangui; Zhang, Liyun; Dai, Haifeng; Li, Huali

    2015-05-01

    We present new photometry of the eclipsing binary ZZ Cyg. From all accumulated eclipsing times, we constructed the (O-C) curve, which can be described by a downward parabola with a possible light-time orbit. The period decrease rate is dP / dt = - 5.73 (± 0.18) dyr-1 . The modulated period, semi-amplitude and eccentricity for the light-time orbit are Pmod = 71.4 (± 1.1)yr , A = 0.0071 (± 0.0005)day and e = 0.420 (± 0.053) , respectively. After removing effects of the magnetic activity, this kind of cyclic oscillation may be attributed to light-time effect via an additional companion. By using the W-D code, the photometric model was updated, which identified that ZZ Cyg is a near-contact binary. We find that a hot spot may occur on the primary that explains the asymmetric light curve. The secular period decrease may possibly cause the fill-out factor of the primary to increase. Finally it will finally fill its Roche lobe. This kind of binary, ZZ Cyg, may evolve into contact binary star.

  15. ABSOLUTE DIMENSIONS OF THE G7+K7 ECLIPSING BINARY STAR IM VIRGINIS: DISCREPANCIES WITH STELLAR EVOLUTION MODELS

    SciTech Connect

    Morales, Juan Carlos; Marschall, Laurence A.; Brehm, William

    2009-12-10

    We report extensive spectroscopic and differential photometric BVRI observations of the active, detached, 1.309-day double-lined eclipsing binary IM Vir, composed of a G7-type primary and a K7 secondary. With these observations, we derive accurate absolute masses and radii of M {sub 1} = 0.981 +- 0.012 M {sub sun}, M {sub 2} = 0.6644 +- 0.0048 M {sub sun}, R {sub 1} = 1.061 +- 0.016 R {sub sun}, and R {sub 2} = 0.681 +- 0.013 R {sub sun} for the primary and secondary, with relative errors under 2%. The effective temperatures are 5570 +- 100 K and 4250 +- 130 K, respectively. The significant difference in mass makes this a favorable case for comparison with stellar evolution theory. We find that both stars are larger than the models predict, by 3.7% for the primary and 7.5% for the secondary, as well as cooler than expected, by 100 K and 150 K, respectively. These discrepancies are in line with previously reported differences in low-mass stars, and are believed to be caused by chromospheric activity, which is not accounted for in current models. The effect is not confined to low-mass stars: the rapidly rotating primary of IM Vir joins the growing list of objects of near-solar mass (but still with convective envelopes) that show similar anomalies. The comparison with the models suggests an age of 2.4 Gyr for the system, and a metallicity of [Fe/H] approx-0.3 that is consistent with other indications, but requires confirmation.

  16. UPPER BOUNDS ON r-MODE AMPLITUDES FROM OBSERVATIONS OF LOW-MASS X-RAY BINARY NEUTRON STARS

    SciTech Connect

    Mahmoodifar, Simin; Strohmayer, Tod

    2013-08-20

    We present upper limits on the amplitude of r-mode oscillations and gravitational-radiation-induced spin-down rates in low-mass X-ray binary neutron stars, under the assumption that the quiescent neutron star luminosity is powered by dissipation from a steady-state r-mode. For masses <2 M{sub Sun} we find dimensionless r-mode amplitudes in the range from about 1 Multiplication-Sign 10{sup -8} to 1.5 Multiplication-Sign 10{sup -6}. For the accreting millisecond X-ray pulsar sources with known quiescent spin-down rates, these limits suggest that {approx}< 1% of the observed rate can be due to an unstable r-mode. Interestingly, the source with the highest amplitude limit, NGC 6440, could have an r-mode spin-down rate comparable to the observed, quiescent rate for SAX J1808-3658. Thus, quiescent spin-down measurements for this source would be particularly interesting. For all sources considered here, our amplitude limits suggest that gravitational wave signals are likely too weak for detection with Advanced LIGO. Our highest mass model (2.21 M{sub Sun }) can support enhanced, direct Urca neutrino emission in the core and thus can have higher r-mode amplitudes. Indeed, the inferred r-mode spin-down rates at these higher amplitudes are inconsistent with the observed spin-down rates for some of the sources, such as IGR J00291+5934 and XTE J1751-305. In the absence of other significant sources of internal heat, these results could be used to place an upper limit on the masses of these sources if they were made of hadronic matter, or alternatively it could be used to probe the existence of exotic matter in them if their masses were known.

  17. Upper Bounds on r-Mode Amplitudes from Observations of Low-Mass X-Ray Binary Neutron Stars

    NASA Technical Reports Server (NTRS)

    Mahmoodifar, Simin; Strohmayer, Tod

    2013-01-01

    We present upper limits on the amplitude of r-mode oscillations and gravitational-radiation-induced spin-down rates in low-mass X-ray binary neutron stars, under the assumption that the quiescent neutron star luminosity is powered by dissipation from a steady-state r-mode. For masses <2M solar mass we find dimensionless r-mode amplitudes in the range from about 1×10(exp-8) to 1.5×10(exp-6). For the accreting millisecond X-ray pulsar sources with known quiescent spin-down rates, these limits suggest that approx. less than 1% of the observed rate can be due to an unstable r-mode. Interestingly, the source with the highest amplitude limit, NGC 6440, could have an r-mode spin-down rate comparable to the observed, quiescent rate for SAX J1808-3658. Thus, quiescent spin-down measurements for this source would be particularly interesting. For all sources considered here, our amplitude limits suggest that gravitational wave signals are likely too weak for detection with Advanced LIGO. Our highest mass model (2.21M solar mass) can support enhanced, direct Urca neutrino emission in the core and thus can have higher r-mode amplitudes. Indeed, the inferred r-mode spin-down rates at these higher amplitudes are inconsistent with the observed spin-down rates for some of the sources, such as IGR J00291+5934 and XTE J1751-305. In the absence of other significant sources of internal heat, these results could be used to place an upper limit on the masses of these sources if they were made of hadronic matter, or alternatively it could be used to probe the existence of exotic matter in them if their masses were known.

  18. The Discovery of a Second Luminous Low-Mass X-Ray Binary in the Globular Cluster M15

    NASA Technical Reports Server (NTRS)

    White, Nicholas E.; Angelini, Lorella

    2001-01-01

    We report an observation by the Chandra X-Ray Observatory of 4U 2127+119, the X-ray source identified with the globular cluster M15. The Chandra observation reveals that 4U 2127+119 is in fact two bright sources, separated by 2.7 arcsec. One source is associated with AC 211, the previously identified optical counterpart to 4U 2127+119, a low-mass X-ray binary (LMXB). The second source, M15 X-2, is coincident with a 19th U magnitude blue star that is 3.3 arcsec from the cluster core. The Chandra count rate of M15 X-2 is 2.5 times higher than that of AC 211. Prior to the 0.5 arcsec imaging capability of Chandra, the presence of two so closely separated bright sources would not have been resolved. The optical counterpart, X-ray luminosity, and spectrum of M15 X-2 are consistent with it also being an LMXB system. This is the first time that two LMXBs have been seen to be simultaneously active in a globular cluster. The discovery of a second active LMXB in M15 solves a long-standing puzzle where the properties of AC 211 appear consistent with it being dominated by an extended accretion disk corona, and yet 4U 2127+119 also shows luminous X-ray bursts requiring that the neutron star be directly visible. The resolution of 4U 2127+119 into two sources suggests that the X-ray bursts did not come from AC 211 but rather from M15 X-2. We discuss the implications of this discovery for understanding the origin and evolution of LMXBs in globular clusters as well as X-ray observations of globular clusters in nearby galaxies.

  19. Unveiling the environment surrounding low-mass X-ray binary SAX J1808.4-3658

    NASA Astrophysics Data System (ADS)

    Pinto, C.; Costantini, E.; Fabian, A. C.; Kaastra, J. S.; in't Zand, J. J. M.

    2014-03-01

    Context. Low-mass X-ray binaries (LMXBs) are a natural workbench to study accretion disk phenomena and optimal background sources to measure elemental abundances in the interstellar medium (ISM). In high-resolution XMM-Newton spectra, the LMXB SAX J1808.4-3658 in the past showed a neon column density significantly higher than expected given its small distance, presumably due to additional absorption from a neon-rich circumstellar medium (CSM). Aims: It is possible to detect intrinsic absorption from the CSM by evidence of Keplerian motions or outflows. For this purpose, we analyze a recent, deep (100 ks long), high-resolution Chandra/LETGS spectrum of SAX J1808.4-3658 in combination with archival data. Methods: We estimated the column densities of the different absorbers through the study of their absorption lines. We used both empirical and physical models involving photo- and collisional-ionization to determine the nature of the absorbers. Results: The abundances of the cold interstellar gas match the solar values as expected given the proximity of the X-ray source. For the first time in this source, we detected neon and oxygen blueshifted absorption lines, which can be well modeled with outflowing photoionized gas. The wind is neon rich (Ne/O ≳ 3) and may originate from processed, ionized gas near the accretion disk or its corona. The kinematics (v = 500-1000 km s-1) are indeed similar to those seen in other accretion disks. We also discovered a system of emission lines with very high Doppler velocities (v ~ 24 000 km s-1) originating presumably closer to the compact object. Additional observations and UV coverage are needed to accurately determine the abundances and the ionization structure of the wind.

  20. The Discovery of a Second Luminous Low Mass X-ray Binary in the Globular Cluster M15

    NASA Technical Reports Server (NTRS)

    White, Nicholas E.; Angelini, Lorella

    2001-01-01

    We report an observation by the Chandra X-ray Observatory of 4U2127+119, the X-ray source identified with the globular cluster M15. The Chandra observation reveals that 4U2127+119 is in fact two bright sources, separated by 2.7". One source is associated with AC21 1, the previously identified optical counterpart to 4U2127+119, a low mass X-ray binary (LMXB). The second source, M15-X2, is coincident with a 19th U magnitude blue star that is 3.3" from the cluster core. The Chandra count rate of M15-X2 is 2.5 times higher than that of AC211. Prior to the 0.5" imaging capability of Chandra the presence of two so closely separated bright sources would not have been resolved, The optical counterpart, X-ray luminosity and spectrum of M15-X2 are consistent with it also being an LMXB system. This is the first time that two LMXBS have been seen to be simultaneously active in a globular cluster. The discovery of a second active LMXB in M15 solves a long standing puzzle where the properties of AC211 appear consistent with it being dominated by an extended accretion disk corona, and yet 4U2127+119 also shows luminous X-ray bursts requiring that the neutron star be directly visible. The resolution of 4U2127+119 into two sources suggests that the X-ray bursts did not come from AC211, but rather from M15X2. We discuss the implications of this discovery for understanding the origin and evolution of LMXBs in GCs as well as X-ray observations of globular clusters in nearby galaxies.

  1. The X-ray dust-scattered rings of the black hole low-mass binary V404 Cyg

    NASA Astrophysics Data System (ADS)

    Vasilopoulos, G.; Petropoulou, M.

    2016-02-01

    We report on the first detection of X-ray dust-scattered rings from the Galactic low-mass X-ray binary V404 Cyg. The observation of the system with Swift/XRT on 2015 June 30 revealed the presence of five concentric ring-like structures centred at the position of V404 Cyg. Follow-up Swift/XRT observations allowed a time-dependent study of the X-ray rings. Assuming that these are the result of small-angle, single X-ray scattering by dust grains along the line of sight, we find that their angular size scales as θ ∝ √{t} in agreement with theoretical predictions. The dust grains are concentrated in five dust layers located at about 2.12, 2.05, 1.63, 1.50 and 1.18 kpc from the observer. These coincide roughly with locations of enhanced extinction as determined by infrared photometry. Assuming that the grain size distribution is described by a generalized Mathis-Rumpl-Nordsieck model, we find that the power-law index of the most distant cloud is q ˜ 4.4, while q ˜ 3.5-3.7 in all other clouds. We constrain at a 3σ level the maximum grain size of the intermediate dust layers in the range 0.16-0.20 μm and set a lower limit of ˜ 0.2 μm in the other clouds. Hints of an exponential cutoff at the angular intensity profile of the outermost X-ray ring suggest that the smallest grains have sizes 0.01 ≤ αmin ≲ 0.03 μm. Based on the relative ratios of dust column densities we find the highest dust concentration at ˜1.6 kpc. Our results indicate a gradient in the dust properties within 1 kpc from V404 Cyg.

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

    NASA Astrophysics Data System (ADS)

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

    1989-11-01

    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.

  3. 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.

  4. THE SDSS-HET SURVEY OF KEPLER ECLIPSING BINARIES: SPECTROSCOPIC DYNAMICAL MASSES OF THE KEPLER-16 CIRCUMBINARY PLANET HOSTS

    SciTech Connect

    Bender, Chad F.; Mahadevan, Suvrath; Deshpande, Rohit; Wright, Jason T.; Roy, Arpita; Terrien, Ryan C.; Sigurdsson, Steinn; Ramsey, Lawrence W.; Schneider, Donald P.; Fleming, Scott W.

    2012-06-01

    We have used high-resolution spectroscopy to observe the Kepler-16 eclipsing binary as a double-lined system and measure precise radial velocities for both stellar components. These velocities yield a dynamical mass ratio of q = 0.2994 {+-} 0.0031. When combined with the inclination, i 90.{sup 0}3401{sup +0.0016}{sub -0.0019}, measured from the Kepler photometric data by Doyle et al. (D11), we derive dynamical masses for the Kepler-16 components of M{sub A} = 0.654 {+-} 0.017 M{sub Sun} and M{sub B} = 0.1959 {+-} 0.0031 M{sub Sun }, a precision of 2.5% and 1.5%, respectively. Our results confirm at the {approx}2% level the mass-ratio derived by D11 with their photometric-dynamical model (PDM), q = 0.2937 {+-} 0.0006. These are among the most precise spectroscopic dynamical masses ever measured for low-mass stars and provide an important direct test of the results from the PDM technique.

  5. 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.

  6. 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).

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

    SciTech Connect

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

    2010-10-01

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

  8. 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

    2013-03-01

    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. PMID:23467166

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

    SciTech Connect

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

    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 potentially offer very robust characterization of these systems. Until recently, only one case has been discovered with Kepler. We cross-correlate the detected red giant and eclipsing-binary catalogs from Kepler data to find possible candidate systems. Light-curve modeling and mean properties measured from asteroseismology are combined to yield specific measurements of periods, masses, radii, temperatures, eclipse timing variations, core rotation rates, and red giant evolutionary state. After using three different techniques to eliminate false positives, out of the 70 systems common to the red giant and eclipsing-binary catalogs we find 13 strong candidates (12 previously unknown) to be eclipsing binaries, one to be a non-eclipsing binary with tidally induced oscillations, and 10 more to be hierarchical triple systems, all of which include a pulsating red giant. The systems span a range of orbital eccentricities, periods, and spectral types F, G, K, and M for the companion of the red giant. One case even suggests an eclipsing binary composed of two red giant stars and another of a red giant with a {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

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

    NASA Astrophysics Data System (ADS)

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

    2008-11-01

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

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

    SciTech Connect

    Qian, S.-B.; Dai, Z.-B.; Liao, W.-P.; Zhu, L.-Y.; Liu, L.; Zhao, E. G.

    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 presence 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.

  12. Orbital period variation study of massive Beta-Lyrae eclipsing binary IU Auriga

    NASA Astrophysics Data System (ADS)

    Yilan, Erkan; Bulut, İbrahim

    2016-07-01

    The system IU Aur is a semi-detached close binary system with an orbital period of 1.81 days, containing a massive star. The O-C diagram of this binary was analyzed with the least-squares method by using all available times of minima. We have found a periodic change of orbital period of IU Aur. This change has been explained by the gravitational effects of a third companion on the binay star. The orbit Parameters of the third body have been derived from the analysis of the O-C curve. The analysis indicates that the eclipsing binary revolves around a third-body with a mass of about M_{3}>10M_{⊙} in a highly eccentric orbit.

  13. The apsidal motion of the eccentric eclipsing binary DI Herculis - An apparent discrepancy with general relativity

    NASA Technical Reports Server (NTRS)

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

    1985-01-01

    The apsidal motion of the eccentric eclipsing binary DI Herculis (HD 175227) is determined from an analysis of the available observations and eclipse timings from 1959 to 1984. Least squares solutions to the primary and secondary minima extending over an 84-yr interval yielded a small advance of periastron omega dot of 0.65 deg/100 yr + or - 0.18/100 yr. The observed advance of the periastron is about one seventh of the theoretical value of 4.27 deg/100 yr that is expected from the combined relativistic and classical effects. The discrepancy is about -3.62 deg/100 yr, or a magnitude of about 20 sigma. Classical mechanisms which explain the discrepancy are discussed, together with the possibility that there may be problems with general relativity itself.

  14. Light curve solutions and out-of-eclipse variabilities of six eccentric Kepler binaries

    NASA Astrophysics Data System (ADS)

    Kjurkchieva, D.; Vasileva, D.; Dimitrov, D.

    2016-04-01

    As a result from light curve solutions of six eccentric Kepler binaries we determined their orbital elements and stellar parameters. We established linear dependence of their eccentricities on the orbital periods. Besides eclipses all targets reveal out-of-eclipse light variabilities modulated on different time scales. KIC 11409698, KIC 5284133 and KIC 8316503, the targets with the biggest eccentricities in our sample, exhibit tidally induced light brightening (hump) around the periastron phase. Just they reveal considerable reflection effect due to the big temperature difference of their components (above 2200 K). The detected humps confirmed the theoretical dependence of the hump amplitude on the eccentricity and mass ratio. KIC 12557713 and KIC 7691527 show photospheric activity caused by two diametrically opposite cool spots on the lateral sides of their primary components (flip-flop effect). We found flares in the Kepler data of KIC 7691527 that is another appearance of the activity of this target.

  15. The long-period binary AL Velorum - The atmospheric eclipse of a bright K0 giant

    NASA Technical Reports Server (NTRS)

    Eaton, Joel A.; Kondo, Yoji; Shore, Steven N.; Mccluskey, George F., Jr.

    1990-01-01

    The properties of the AL Vel binary system, a Zeta Aur system containing a B dwarf and a bright K0 giant, are reviewed with reference to IUE observations of its atmospheric eclipse and eclipse of the accretion disk around the B-dwarf component. It is found that the conditions in the chromosphere are rather similar to those in the Zeta Aur supergiants, once allowance is made for the different sizes and scale heights involved. The conditions for Mg II suppression in the wind through ionization by the B star is discussed, and it is found that radiative excitation and subsequent ionization will suffice for the conditions encountered in the AL Vel system.

  16. Photometric and Spectroscopic Analysis of the Eclipsing Binary DQ Velorum

    NASA Astrophysics Data System (ADS)

    Barría, D.; Mennickent, R. E.; Schmidtobreick, L.; Djurašević, G.; Kołaczkowski, Z.; Michalska, G.; Vučković, M.; Niemczura, E.

    In order to obtain the main stellar and orbital parameters of the Double Periodic Variable DQ Velorum, we have carried out a series of spectroscopic and photometric observations covering several orbital cycles. We disentangle DQ Vel composite spectra and measure radial velocities using an iterative method for double spectroscopic binaries. We obtain the spectroscopic mass ratio q=0.31±0.03 from the radial velocity curves. We compare our single-lined spectra with a grid of synthetic spectra and estimate the temperature of the stars. We also model the V-band light curve using a fitting method based on the simplex algorithm including an accretion disc. We find that DQ Vel is a semi-detached system consisting on a B3V gainer (T_{g}=18500±500 K) and an A1III donor star (T_{d}=9400±100 K) plus an extended accretion disc around the gainer. We compare the stellar and disc parameters of DQ Vel with the DPV V393 Sco to investigate the nature and evolution of these two similar DPV systems.

  17. SARA South Observations and Analysis of the Solar Type, Totally Eclipsing, Contact Binary, DD Indus

    NASA Astrophysics Data System (ADS)

    Samec, Ronald G.; Norris, Cody; Van Hamme, Walter V.; Faulkner, Danny R.

    2016-06-01

    DD Ind (NSVS5066754) is a Solar Type (T ~ 5850K) solar type eclipsing binary. It was observed in June to September, 2013 at Cerro Tololo in remote mode with the 0.6-m SARA South reflector. Five times of minimum light were calculated from our present observations, for three primary and two secondary eclipses: HJD Min I = 2456505.8085±0.0002, 2456533.73933±0.00003, 2456536.6378±0.0012HJD Min II = 2456503.8132±00.0014, 2456533.5583±0.0004In addition, two observations at minima were determined from archived All Sky Automated Survey Data:HJD Min II = 2452872.9104, 2452883.6097.The following quadratic ephemerides was determined from all available times of minimum light:JD Hel Min I=2456533.7394±0.0002d + 0.3627463±0.0000002 X E +0.00000000006 ± 0.00000000002 X E2A BVRcIc filtered simultaneous Wilson-Devinney Program (W-D) solution reveals that the system has a mass ratio of ~0.46, and a component temperature difference of ~200 K. Two weak (Tfact ~ 0.95, ~20 degree radius) cool spots were iterated on the secondary component in the WD Synthetic Light Curve Computations. They appeared in the Northern Hemisphere (colatitude 45 degrees) and near the equator (colatitude ~95 degrees), respectively.The Roche Lobe fill-out of the binary is ~13%. The inclination is ~84.8o. An eclipse duration of ~16 minutes was determined for the primary eclipse. Additional and more detailed information is given in the meeting report.

  18. NLTE spectral analysis of the sdOB primary of the eclipsing binary system LB 3459 (AA Dor)

    NASA Astrophysics Data System (ADS)

    Rauch, T.

    2000-04-01

    We present a spectral analysis of the sdOB primary star of the binary system LB 3459 based on high-resolution high-S/N optical and UV spectra. The metal abundances are determined by means of state-of-the-art NLTE model atmospheres. We determined Teffw42 and log gw{5.2} within very small error limits. The He (1/125 solar), C (1/265), N (1/33), O (1/12), and Si (1/5) abundances appear strongly depleted while that of Fe and Ni are roughly solar and Mg is strongly enriched by a factor of 6. The spectroscopic distance to LB 3459 is d = 396 pc. The mass of the primary component of LB 3459 is 0.330 M_sun derived from comparisons with theoretical models for sdO stars in the log T_eff - \\log g plane. The mass of the secondary is then 0.066 M_sun derived from the mass function. There remains some disagreement between the radius derived from log g and the above mass, and that derived from analysis of the radial-velocity curve and the eclipse curves. LB 3459 is a close binary system which had experienced a common envelope (CE) phase during its evolution. It fits in the ``low mass case B'' scenario of Iben & Livio (1993) and the secondary is a brown dwarf. The spectroscopically determined rotational velocity of the primary is v_rot = 34 ± 10 km* sec-1. Thus even bound rotation (v_rot = 45.7 km* sec-1) cannot be ruled out. Based on observations collected at the European Southern Observatory, La Silla, Chile (proposals 55.D-0319, 56.C-0165) and on data retrieved from the International Ultraviolet Explorer (IUE) Final Archive.

  19. A search for substellar objects orbiting the sdB eclipsing binary HS 0705+6700

    NASA Astrophysics Data System (ADS)

    Qian, S.-B.; Shi, G.; Zola, S.; Koziel-Wierzbowska, D.; Winiarski, M.; Szymanski, T.; Ogloza, W.; Li, L.-J.; Zhu, L.-Y.; Liu, L.; He, J.-J.; Liao, W.-P.; Zhao, E.-G.; Wang, J.-J.; Zhang, J.; Jiang, L.-Q.

    2013-12-01

    By using 78 newly determined timings of light minima together with those collected from the literature, we analysed the changes in the observed minus calculated (O-C) diagram in HS 0705+6700, a short-period (2.3 h) eclipsing binary that consists of a very hot subdwarf B-type (sdB) star and a very cool fully convective red dwarf. We confirmed the cyclic variation in the O-C and refined the parameters of the circumbinary brown dwarf (reported to orbit the binary system in 2009) by analysing the changes for the light travel time effect that arises from the gravitational influence of the third body. Our results indicate the lower mass limit of the third body to be M3 sin i' = 33.7(±1.6) MJup. This companion would be a brown dwarf if its orbital inclination is larger than 27.7° and it is orbiting the central eclipsing binary with an eccentricity e ˜ 0.2 at a separation of about 3.7(±0.1) au.

  20. 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.

  1. A First Robust Measurement of the Aging of Field Low Mass X-ray Binary Populations from Hubble and Chandra

    NASA Astrophysics Data System (ADS)

    Lehmer, Bret

    Our understanding of X-ray binary (XRB) formation and evolution have been revolutionized by HST and Chandra by allowing us to study in detail XRBs in extragalactic environments. Theoretically, XRB formation is sensitive to parent stellar population properties like metallicity and stellar age. These dependencies not only make XRBs promising populations for aiding in the measurement of galaxy properties themselves, but also have important astrophysical implications. For example, due to the relatively young stellar ages and primordial metallicities in the early Universe (z > 3), it is predicted that XRBs were more luminous than today and played a significant role in the heating of the intergalactic medium. Unlocking the potential of XRBs as useful probes of galaxy properties and understanding in detail their evolutionary pathways critically requires empirical constraints using well-studied galaxies that span a variety of evolutionary stages. In this ADAP, we will use the combined power of archival observations from Hubble and Chandra data of 16 nearby early-type galaxies to study how low-mass XRBs (LMXBs) populations evolve with age. LMXBs are critically important since they are the most numerous XRBs in the MW and are expected to dominate the normal galaxy Xray emissivity of the Universe out to z ~ 2. Understanding separately LMXBs that form via dynamical interactions (e.g., in globular clusters; GCs) versus those that form in-situ in galactic fields is an important poorly constrained area of XRB astrophysics. We are guided by the following key questions: 1. How does the shape and normalization of the field LMXB X-ray luminosity function (XLF) evolve as parent stellar populations age? Using theoretical population synthesis models, what can we learn about the evolution of contributions from various LMXB donor stars (e.g., red-giant, main-sequence, and white dwarf donors)? 2. Is there any evidence that globular cluster (GC) LMXBs seeded field LMXB populations through

  2. DISCOVERY OF A SECOND TRANSIENT LOW-MASS X-RAY BINARY IN THE GLOBULAR CLUSTER NGC 6440

    SciTech Connect

    Heinke, C. O.; Budac, S. A.; Altamirano, D.; Linares, M.; Wijnands, R.; Cohn, H. N.; Lugger, P. M.; Servillat, M.; Grindlay, J. E.; Strohmayer, T. E.; Markwardt, C. B.; Swank, J. H.; Bailyn, C.

    2010-05-01

    We have discovered a new transient low-mass X-ray binary, NGC 6440 X-2, with Chandra/ACIS, RXTE/PCA, and Swift/XRT observations of the globular cluster NGC 6440. The discovery outburst (2009 July 28-31) peaked at L{sub X} {approx} 1.5 x 10{sup 36} erg s{sup -1} and lasted for <4 days above L{sub X} = 10{sup 35} erg s{sup -1}. Four other outbursts (2009 May 29-June 4, August 29-September 1, October 1-3, and October 28-31) have been observed with RXTE/PCA (identifying millisecond pulsations) and Swift/XRT (confirming a positional association with NGC 6440 X-2), with similar peak luminosities and decay times. Optical and infrared imaging did not detect a clear counterpart, with best limits of V>21, B>22 in quiescence from archival Hubble Space Telescope imaging, g'>22 during the August outburst from Gemini-South GMOS imaging, and J {approx_gt} 18.5 and K {approx_gt} 17 during the July outburst from CTIO 4 m ISPI imaging. Archival Chandra X-ray images of the core do not detect the quiescent counterpart (L{sub X} < (1-2) x 10{sup 31} erg s{sup -1}) and place a bolometric luminosity limit of L{sub NS} < 6 x 10{sup 31} erg s{sup -1} (one of the lowest measured) for a hydrogen atmosphere neutron star. A short Chandra observation 10 days into quiescence found two photons at NGC 6440 X-2's position, suggesting enhanced quiescent emission at L{sub X} {approx} 6 x 10{sup 31} erg s{sup -1}. NGC 6440 X-2 currently shows the shortest recurrence time ({approx}31 days) of any known X-ray transient, although regular outbursts were not visible in the bulge scans before early 2009. Fast, low-luminosity transients like NGC 6440 X-2 may be easily missed by current X-ray monitoring.

  3. Parameter estimation using a complete signal and inspiral templates for low-mass binary black holes with Advanced LIGO sensitivity

    NASA Astrophysics Data System (ADS)

    Cho, Hee-Suk

    2015-12-01

    We study the validity of inspiral templates in gravitational wave data analysis with Advanced LIGO sensitivity for low mass binary black holes with total masses of M≤slant 30{M}⊙ . We mainly focus on the nonspinning system. As our complete inspiral-merger-ringdown waveform model ({I}{M}{R} ), we assume the phenomenological model, ‘PhenomA’, and define our inspiral template model ({{I}}{{merg}}) by taking the inspiral part into account from {I}{M}{R} up to the merger frequency ({f}{{merg}}). We first calculate the true statistical uncertainties using {I}{M}{R} signals and {I}{M}{R} templates. Next, using {I}{M}{R} signals and {{I}}{{merg}} templates, we calculate fitting factors and systematic biases, and compare the biases with the true statistical uncertainties. We find that the valid criteria of the bank of {{I}}{{merg}} templates are obtained as {M}{{crit}}˜ 24{M}⊙ for detection (if M\\gt {M}{{crit}}, the fitting factor is smaller than 0.97), and {M}{{crit}}˜ 26{M}⊙ for parameter estimation (if M\\gt {M}{{crit}}, the systematic bias is larger than the true statistical uncertainty where the signal-to-noise ratio is 20), respectively. In order to see the dependence on the cutoff frequency of the inspiral waveforms, we define another inspiral model {{I}}{{isco}} which is terminated at the innermost-stable-circular-orbit frequency ({f}{{isco}}\\lt {f}{{merg}}). We find that the valid criteria of the bank of {{I}}{{isco}} templates are obtained as {M}{{crit}}˜ 15{M}⊙ and ˜ 17{M}⊙ for detection and parameter estimation, respectively. We investigate the statistical uncertainties for the inspiral template models considering various signal-to-noise ratios, and compare those to the true statistical uncertainties. We also consider the aligned-spinning system with fixed mass ratio ({m}1/{m}2=3) and spin (χ =0.5) by employing the recent phenomenological model, ‘PhenomC’. In this case, we find that the true statistical uncertainties can be much larger

  4. 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.

  5. The orbital periods of three sdB eclipsing binary systems

    NASA Astrophysics Data System (ADS)

    Kilkenny, D.

    2014-12-01

    Recent timings of eclipses made between 2011 and 2014 are presented for three binary systems with hot subdwarf primary stars, AA Dor, NY Vir and EC 10246-2707. In the case of AA Dor, the period remains constant. In NY Vir, a rapidly pulsating sdBVr with a cool companion, the period change now appears more complex than can be described by a simple quadratic. EC 10246-2707, which has previously appeared to have a constant period, now appears to be showing a significant period increase. The effect of gravitational radiation in HW Vir-like systems is briefly discussed.

  6. Times of Minima and New Ephemerides for Southern Hemisphere Eclipsing Binary Stars Observed in 2015

    NASA Astrophysics Data System (ADS)

    Pavlov, H.; Mallama, A.; Loader, B.; Kerr, S.

    2016-06-01

    Observers from Australia and New Zealand used video equipment to time eclipses of short-period binary stars. The objects were typically south of -20o declination and had periods of less than a day. Many of those systems had very few observations since their discovery and some of them had not been observed for 50 or more years. We present 44 times of minima of 42 stars, provide revised ephemerides for 7 of these systems and characterize an orbital period change for RW PsA.

  7. Times of Minima and New Ephemerides for Southern Hemisphere Eclipsing Binary Stars Observed in 2015

    NASA Astrophysics Data System (ADS)

    Pavlov, H.; Mallama, A.; Loader, B.; Kerr, S.

    2016-04-01

    Observers from Australia and New Zealand used video equipment to time eclipses of short-period binary stars. The objects were typically south of -20o declination and had periods of less than a day. Many of those systems had very few observations since their discovery and some of them had not been observed for 50 or more years. We present 44 times of minima of 42 stars, provide revised ephemerides for 7 of these systems and characterize an orbital period change for RW PsA.

  8. Radio pulsar style timing of eclipsing binary stars from the All Sky Automated Survey catalogue

    NASA Astrophysics Data System (ADS)

    Kozłowski, S. K.; Konacki, M.; Sybilski, P.

    2011-09-01

    The light-time effect (LTE) is observed whenever the distance between the observer and any kind of periodic event changes in time. The usual cause of this change in the distance is the reflex motion about the system's barycentre due to the gravitational influence of one or more additional bodies. We analyse 5032 eclipsing contact (EC) and eclipsing detached (ED) binaries from the All Sky Automated Survey (ASAS) catalogue to detect variations in the times of eclipses which possibly can be due to the LTE effect. To this end we use an approach known from the radio pulsar timing where a template radio pulse of a pulsar is used as a reference to measure the times of arrivals of the collected pulses. In our analysis, as a template for a photometric time series from the ASAS, we use a best-fitting trigonometric series representing the light curve of a given EC or ED. Subsequently, an observed minus calculated (O-C) diagram is built by comparing the template light curve with light curves obtained from subsets of a given time series. Most of the variations we detect in O-C diagrams correspond to a linear period change. Three of the O-C diagrams show evidence of more than one complete LTE orbit. For these objects we obtain preliminary orbital solutions. Our results demonstrate that the timing analysis employed in radio pulsar timing can be effectively used to study large data sets from photometric surveys.

  9. ASAS LIGHT CURVES OF INTERMEDIATE-MASS ECLIPSING BINARY STARS AND THE PARAMETERS OF HI Mon

    SciTech Connect

    Williams, S. J.; Gies, D. R.; Matson, R. A.; Caballero-Nieves, S.; Helsel, J. W. E-mail: gies@chara.gsu.edu E-mail: scaballero@chara.gsu.edu

    2011-07-15

    We present a catalog of 56 candidate intermediate-mass eclipsing binary systems extracted from the third data release of the All Sky Automated Survey. We gather pertinent observational data and derive orbital properties, including ephemerides, for these systems as a prelude to anticipated spectroscopic observations. We find that 37 of the 56, or {approx}66%, of the systems are not identified in the Simbad Astronomical Database as known binaries. As a specific example, we show spectroscopic data obtained for the system HI Mon (B0 V + B0.5 V) observed at key orbital phases based on the computed ephemeris, present a combined spectroscopic and photometric solution for the system, and give stellar parameters for each component.

  10. Multiband Photometry of Southern Very Short Period Eclipsing Binaries. I. V676 Centauri

    NASA Astrophysics Data System (ADS)

    Gray, J. D.; Samec, R. G.; Woissol, S. L.

    1996-05-01

    In this paper, we extend our study of solar-type binaries near the the low period limit to include Southern hemisphere systems. Observations are being taken at Cerro Tololo Inter-American Observatory, Chile. Here, we report B,V,R,I observations of V676 Centauri. Our three nights of data were taken in May of 1991 with a dry ice cooled Ga-As photometer attached to the 1.0-m reflector. Two new primary and two secondary epochs of minimum light were determined from the observations, and more than 100 minima were collected from the literature. Our period study spans some 35 years. The light curves show a rather large difference in eclipse depths for a W UMa binary. An O'Connell effect lends evidence of spot activity in this very short period ( 0.291 d) system. A preliminary photometric analysis of the light curves is presented.

  11. 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.

  12. 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.

  13. Light Curve Analysis for W UMa-Type Eclipsing Binary Star Systems

    NASA Astrophysics Data System (ADS)

    Henderson, Scott; Peach, N.; Olsen, T.

    2006-12-01

    We report results from summer 2006 in an ongoing study of eclipsing binary stars. Our investigations have focused on the measurement and interpretation of light curves for W UMa-type systems 44i Boötis and VW Cephei. These contact binaries have component stars of spectral type G, and revolve with periods of 6.43 and 6.67 hours. Dome automation and scripting capabilities introduced this summer have significantly reduced experimental uncertainties in our data. In support of previous findings we continue to observe an increase in the orbital period of 44i Boo at a rate of 10.4 µs/epoch or 14.2 ms/yr. Residuals computed after incorporating the increasing period suggest an underlying sinusoidal oscillation with a 61.5 year period and amplitude of 648 seconds. AAPT Member Thomas Olsen is sponsoring the lead presenter, SPS Member Scott Henderson, and the co-presenter, SPS Member Nick Peach.

  14. KIC 6220497: a new Algol-type eclipsing binary with multiperiodic pulsations

    NASA Astrophysics Data System (ADS)

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

    2016-08-01

    We present both binarity and pulsation of KIC 6220497 from the Kepler observations. The light curve synthesis shows that the eclipsing system is a semidetached Algol with parameters of q = 0.243 ± 0.001, i = 77.3 ± 0.3 deg, and ΔT = 3372 ± 58 K, in which the detached primary component fills its Roche lobe by ˜87 per cent. A multiple frequency analysis of the eclipse-subtracted light residuals reveals 33 frequencies in the range of 0.75-20.22 d-1 with amplitudes between 0.27 and 4.56 mmag. Among these, four are pulsation frequencies in fundamental (f1, f5) and p (f2, f7) modes, and six are orbital frequency (f8, f31) and its harmonics (f6, f11, f20, f24), which can be attributed to tidally excited modes. For the pulsation frequencies, the pulsation constants of 0.16-0.33 d and the period ratios of Ppul/Porb = 0.042-0.089 indicate that the primary component is a δ Sct pulsating star and, thus, KIC 6220497 is an oscillating eclipsing Algol (oEA) star. The dominant pulsation period of 0.117 4051 ± 0.000 0004 d is significantly longer than that expected from empirical relations that link the pulsation period with the orbital period. The surface gravity of log g1 = 3.78 ± 0.03 is clearly smaller than those of the other oEA stars with similar orbital periods. The pulsation period and the surface gravity of the pulsating primary demonstrate that KIC 6220497 would be the more evolved eclipsing binary, compared with normal oEA stars.

  15. Revisiting the Anomalous Apsidal Motion of the Eccentric Eclipsing Binary DI Herculis

    NASA Astrophysics Data System (ADS)

    Maloney, F. P.; Guinan, E. F.; Barge, L. M.; Mardling, R. A.

    2003-12-01

    In 1985, Guinan & Maloney presented the detailed analysis of the puzzling eclipsing binary system DI Herculis. This system is rare among main sequence stars in that its apsidal motion is dominated by the effects of General Relativity. The GR contribution to its theoretically predicted apsidal motion is 2.34 o/100 y., whereas the theoretically predicted classical contribution (due to tidal and rotational deformation of the component stars) is 1.93 o/100 y. The interesting fact is that the observed apsidal motion, determined from timings of the stars' mutual eclipses, is anomalously low: ˜1 o/100 y., well below the combined theoretical expectation of 4.27 o/100 y. Since Rudkj\\o bing's (1959) announcement of the special nature of DI Her, observers have been measuring light curves and radial velocity curves to determine the orbital parameters of the system and the stellar properties of its components. DI Her consists of two main sequence stars (B5V and B6V) in a 10.55 day eccentric orbit (e=0.489). Observations of times of minima reveal the system's apsidal motion, computed from the changing displacement of the secondary eclipse from the primary eclipse. Four decades of photoelectric measurements show that the observed apsidal motion remains below that predicted. Various explanations for this discrepancy have been offered, with the most promising involving the presence of a third component of the system. In a highly inclined orbit, the third body would diminish the rate of apsidal advance of the close pair. Adding photometry recently taken with the 0.8 m Four College Automatic Photoelectric Telescope, we present a new determination of the apsidal motion for DI Her. We also present the results from a new formalism for studying three-body interactions by Mardling in the DI Her system. This research is supported by NSF/RUI grant AST00-71260, which we gratefully acknowledge.

  16. The atmospheric structures of the companion stars of eclipsing binary x ray sources

    NASA Technical Reports Server (NTRS)

    Clark, George W.

    1992-01-01

    This investigation was aimed at determining structural features of the atmospheres of the massive early-type companion stars of eclipse x-ray pulsars by measurement of the attenuation of the x-ray spectrum during eclipse transitions and in deep eclipse. Several extended visits were made to ISAS in Japan by G. Clark and his graduate student, Jonathan Woo to coordinate the Ginga observations and preliminary data reduction, and to work with the Japanese host scientist, Fumiaki Nagase, in the interpretation of the data. At MIT extensive developments were made in software systems for data interpretation. In particular, a Monte Carlo code was developed for a 3-D simulation of the propagation of x-rays from the neutron star through the ionized atmosphere of the companion. With this code it was possible to determine the spectrum of Compton-scattered x-rays in deep eclipse and to subtract that component from the observed spectra, thereby isolating the software component that is attributable in large measure to x-rays that have been scattered by interstellar grains. This research has culminated in the submission of paper to the Astrophysical Journal on the determination of properties of the atmosphere of QV Nor, the BOI companion of 4U 1538-52, and the properties of interstellar dust grains along the line of sight from the source. The latter results were an unanticipated byproduct of the investigation. Data from Ginga observations of the Magellanic binaries SMC X-1 and LMC X-4 are currently under investigation as the PhD thesis project of Jonathan Woo who anticipated completion in the spring of 1993.

  17. Apsidal Motion and a Light Curve Solution for 13 LMC Eccentric Eclipsing Binaries

    NASA Astrophysics Data System (ADS)

    Zasche, P.; Wolf, M.; Vraštil, J.; Pilarčík, L.

    2015-12-01

    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 these 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⊙ 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. Based on data collected with the Danish 1.54 m telescope at the ESO La Silla Observatory.

  18. Eclipsing time variations in close binary systems: Planetary hypothesis vs. Applegate mechanism

    NASA Astrophysics Data System (ADS)

    Völschow, M.; Schleicher, D. R. G.; Perdelwitz, V.; Banerjee, R.

    2016-03-01

    The observed eclipsing time variations in post-common-envelope binaries (PCEBs) can be interpreted as potential evidence for massive Jupiter-like planets, or as a result of magnetic activity, leading to quasi-periodic changes in the quadrupole moment of the secondary star. The latter is commonly referred to as the Applegate mechanism. We employ an improved version of Applegate's model including the angular momentum exchange between a finite shell and the core of the star. The framework is employed to derive the general conditions under which the Applegate mechanism can work, and is subsequently applied to a sample of 16 close binary systems with potential planets, including eleven PCEBs. Further, we present a detailed derivation and study of analytical models that allow for an straightforward extension to other systems. Using our full numerical framework, we show that the Applegate mechanism can clearly explain the observed eclipsing time variations in four of the systems, while the required energy to produce the quadrupole moment variations is too high in at least eight systems. In the remaining four systems, the required energy is comparable to the available energy produced by the stars, which we consider borderline cases. Therefore, the Applegate mechanism cannot uniquely explain the observed period time variations for this entire population. Even in systems where the required energy is too high, the Applegate mechanism may provide an additional scatter, which needs to be considered in the derivation and analysis of planetary models.

  19. Absolute properties of the main-sequence eclipsing binary FM Leo

    NASA Astrophysics Data System (ADS)

    Ratajczak, M.; Kwiatkowski, T.; Schwarzenberg-Czerny, A.; Dimitrov, W.; Konacki, M.; Hełminiak, K. G.; Bartczak, P.; Fagas, M.; Kamiński, K.; Kankiewicz, P.; Borczyk, W.; Rożek, A.

    2010-03-01

    First spectroscopic and new photometric observations of the eclipsing binary FM Leo are presented. The main aims were to determine the orbital and stellar parameters of the two components and their evolutionary stage. First spectroscopic observations of the system were obtained with the David Dunlap Observatory and Poznań Spectroscopic Telescope spectrographs. The results of the orbital solution from radial velocity curves are combined with those derived from the light-curve analysis (V-band photometry from the All Sky Automated Survey and supplementary observations of eclipses with the 1 and 0.35m telescopes) to derive orbital and stellar parameters. JKTEBOP, Wilson-Devinney binary modelling codes and a two-dimensional cross-correlation method were applied for the analysis. We find the masses to be M1 = 1.318 +/- 0.007 and M2 = 1.287 +/- 0.007Msolar and the radii to be R1 = 1.648 +/- 0.043 and R2 = 1.511 +/- 0.049 Rsolar for primary and secondary stars, respectively. The evolutionary stage of the system is briefly discussed by comparing physical parameters with current stellar evolution models. We find that the components are located at the main sequence, with an age of about 3Gyr.

  20. ANALYSIS OF SPIN-ORBIT MISALIGNMENT IN THE ECLIPSING BINARY DI HERCULIS

    SciTech Connect

    Philippov, Alexander A.; Rafikov, Roman R.

    2013-05-10

    The eclipsing binary DI Herculis (DI Her) is known to exhibit anomalously slow apsidal precession below the rate predicted by general relativity. Recent measurements of the Rossiter-McLaughlin effect indicate that stellar spins in DI Her are almost orthogonal to the orbital angular momentum, which explains the anomalous precession in agreement with the earlier theoretical suggestion by Shakura. However, these measurements yield only projections of the spin-orbit angles onto the sky plane, leaving the spin projection onto our line of sight unconstrained. Here we describe a method for determining the full three-dimensional spin orientation of the binary components relying on the use of the gravity-darkening effect, which is significant for the rapidly rotating stars in DI Her. Gravity darkening gives rise to a nonuniform brightness distribution over the stellar surface, the pattern of which depends on the stellar spin orientation. Using archival photometric data obtained during multiple eclipses over several decades, we are able to constrain the unknown spin angles in DI Her with this method, finding that the spin axes of both stars lie close to the plane of the sky. Our procedure fully accounts for the precession of stellar spins over the long time span of observations.

  1. 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

  2. Constraining Kepler Eclipsing Binary Properties with Time-Series and Multi-band Photometry

    NASA Astrophysics Data System (ADS)

    Windemuth, Diana; Agol, Eric

    2015-01-01

    We perform simultaneous fits to time-series (Kepler) and multi-band (SDSS griz + 2MASS JHKs) photometry to constrain stellar and orbital parameters of eclipsing binaries (EBs) from the Kepler Eclipsing Binary Catalogue. We infer the stellar parameters by comparing Padova stellar evolution models to the extinction-corrected multi-band photometric data, and use the results as inputs to a Keplerian orbit model for the lightcurves. This method yields a self-consistent analysis and jointly constrains properties of both stars (orbital elements e, ω, i, tpe, p + stellar parameters rA, rB, mA, mB, fB/fA, [Fe/H], age, and quadratic limb darkening coefficients uA1, uA2, uB1, uB2). We apply our coupled time-series photometry and SED model to a sub-sample of detached EBs with p = 10 - 40 d, to minimize the influence of tidal or Doppler effects. The results of this analysis will feed into our circumbinary planet search, wherein we apply barycentric corrections to the Kepler EB lightcurves to look for signals due to planetary companions.

  3. 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.

  4. XMM-Newton Results on the Ultracompact Low Mass X-Ray Binary 4U 1850-087 in the Globular Cluster NGC 6712

    NASA Astrophysics Data System (ADS)

    Sidoli, L.; Parmar, A. N.; Oosterbroek, T.

    2004-10-01

    We report on preliminary results from our XMM- Newton observation of the Low Mass X-ray Binary 4U 1850-087, located in the galactic globular clus- ter NGC 6712. It is an ultracompact binary system, with an orbital period of 20.6 min. In previous low- resolution X-ray observations 4U 1850-087 displayed a soft excess residual around 0.7 keV, possibly indica- tive of the presence of a high Ne/O ratio, as already found in other three ultracompact LMXBs contain- ing a neutron star (4U 0614+091, 4U 0918-549, and 4U 1543-624). We discuss here our preliminary anal- ysis of high resolution X-ray spectra of 4U 1850-087, and timing results. Key words: X rays; X ray Binaries; individual: 4U 1850-087.

  5. 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.; 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.; Wilson, R. W.

    2016-05-01

    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 yrs, 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 yrs, 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.

  6. 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.

  7. Evidence from Quasi-Periodic Oscillations for a Millisecond Pulsar in the Low Mass X-Ray Binary 4U 0614+091

    NASA Technical Reports Server (NTRS)

    Ford, E.; Kaaret, P.; Tavani, M.; Barret, D.; Bloser, P.; Grindlay, J.; Harmon, B. A.; Paciesas, W. S.; Zhang, S. N.

    1997-01-01

    We have detected quasi-periodic oscillations (QPOs) near 1 kHz from the low mass X-ray binary 4U 0614+091 in observations with RXTE. The observations span several months and sample the source over a large range of X-ray luminosity. In every interval QPOs are present above 400 Hz with fractional RMS amplitudes from 3 to 12% over the full PCA band. At high count rates, two high frequency QPOs are detected simultaneously. The difference of their frequency centroids is consistent with a constant value of 323 Hz in all observations. During one interval a third signal is detected at 328 +/- 2 Hz. This suggests the system has a stable 'clock' which is most likely the neutron star with spin period 3.1 msec. Thus, our observations of 4U 0614+091 and those of 4U 1728-34 provide the first evidence for millisecond pulsars within low-mass X-ray binary systems and reveal the 'missing-link' between millisecond radiopulsars and the late stages of binary evolution in low mass X-ray binaries. The constant difference of the high frequency QPOs sug,,ests a beat-frequency interpretation. In this model, the high frequency QPO is associated with the Keplerian frequency of the inner accretion disk and the lower frequency QPO is a 'beat' between the differential rotation frequency of the inner disk and the spinning neutron star. Assuming the high frequency QPO is a Keplerian orbital frequency for the accretion disk, we find a maximum mass of 1.9 solar mass and a maximum radius of 17 km for the neutron star.

  8. δ Sct-type pulsations in eclipsing binary systems: Y Cam

    NASA Astrophysics Data System (ADS)

    Rodríguez, E.; García, J. M.; Costa, V.; Lampens, P.; van Cauteren, P.; Mkrtichian, D. E.; Olson, E. C.; Amado, P. J.; Daszyńska-Daszkiewicz, J.; Turcu, V.; Kim, S.-L.; Zhou, A. Y.; López-González, M. J.; Rolland, A.; Díaz-Fraile, D.; Wood, M. A.; Hintz, E.; Pop, A.; Moldovan, D.; Etzel, P. B.; Casanova, V.; Sota, A.; Aceituno, F. J.; Lee, D.-J.

    2010-11-01

    We present the results of a three-continent multisite photometric campaign carried out on the Algol-type eclipsing binary system Y Cam, in which the primary component is a multiperiodic δ Sct-type pulsator. The observations consist of 86 nights and more than 450 h of useful data collected mainly during the Northern winter 2002-2003. This means that this is the most extensive time series for such kind of systems obtained so far. These observations were collected mostly in the Johnson V filter, but they also include, for the first time, nearly complete binary light curves in simultaneous Strömgren uvby filters together with a few Crawford Hβ data obtained around the orbital phase of the first quadrature. A detailed photometric analysis is presented for both binarity and pulsation. The results indicate a semidetached system with the secondary filling its Roche lobe. No significant contribution from a third body is found. The residuals from the computed binary solution were then used to investigate the pulsational content of the primary component. The frequency analysis of the out-of-primary-eclipse data leads to a set of eight significant and independent pulsational peaks in a well-defined region of the frequency domain. This means that this is the largest set of excited modes discovered so far in the pulsating component of such kind of systems. The possibility of aliasing problems during the present run or short-term time-scale amplitude variations in some of them was investigated with null results. Indeed the results indicate that f1 and f3 form a frequency doublet with a beat period of Pbeat = 17.065 d. Our results confirm the frequencies already detected by earlier authors and show the presence of some additional significant peaks. The observed amplitudes during the present run are also consistent with those derived from older data sets. We perform a preliminary mode identification for most of the frequencies on the basis of the collected multicolour photometry

  9. Measuring tides and binary parameters from gravitational wave data and eclipsing timings of detached white dwarf binaries

    SciTech Connect

    Shah, Sweta; Nelemans, Gijs

    2014-08-20

    The discovery of the most compact detached white dwarf (WD) binary SDSS J065133.33+284423.3 has been discussed in terms of probing the tidal effects in WDs. This system is also a verification source for the space-based gravitational wave (GW) detector, eLISA, or the evolved Laser Interferometer Space Antenna, which will observe short-period compact Galactic binaries with P {sub orb} ≲ 5 hr. We address the prospects of performing tidal studies using eLISA binaries by showing the fractional uncertainties in the orbital decay rate, f-dot , and the rate of that decay, f{sup ¨} expected from both the GW and electromagnetic (EM) data for some of the high-f binaries. We find that f-dot and f{sup ¨} can be measured using GW data only for the most massive WD binaries observed at high frequencies. From timing the eclipses for ∼10 yr, we find that f-dot can be known to ∼0.1% for J0651. We find that from GW data alone, measuring the effects of tides in binaries is (almost) impossible. We also investigate the improvement in the knowledge of the binary parameters by combining the GW amplitude and inclination with EM data with and without f-dot . In our previous work, we found that EM data on distance constrained the 2σ uncertainty in chirp mass to 15%-25% whereas adding f-dot reduces it to 0.11%. EM data on f-dot also constrain the 2σ uncertainty in distance to 35%-19%. EM data on primary mass constrain the secondary mass m {sub 2} to factors of two to ∼40% whereas adding f-dot reduces this to 25%. Finally, using single-line spectroscopic data constrains 2σ uncertainties in both the m {sub 2}, d to factors of two to ∼40%. Adding EM data on f-dot reduces these 2σ uncertainties to ≤25% and 6%-19%, respectively. Thus we find that EM measurements of f-dot and radial velocity are valuable in constraining eLISA binary parameters.

  10. Determining the Age of the Kepler Open Cluster NGC 6819 With a New Triple System and Other Eclipsing Binary Stars

    NASA Astrophysics Data System (ADS)

    Brewer, Lauren N.; Sandquist, Eric L.; Mathieu, Robert D.; Milliman, Katelyn; Geller, Aaron M.; Jeffries, Mark W., Jr.; Orosz, Jerome A.; Brogaard, Karsten; Platais, Imants; Bruntt, Hans; Grundahl, Frank; Stello, Dennis; Frandsen, Søren

    2016-03-01

    As part of our study of the old (˜2.5 Gyr) open cluster NGC 6819 in the Kepler field, we present photometric (Kepler and ground-based BVRCIC) 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 MB = 1.090 ± 0.010 M⊙ and MC = 1.075 ± 0.013 M⊙, and radii RB = 1.099 ± 0.006 ± 0.005 R⊙ and RC = 1.069 ± 0.006 ± 0.013 R⊙. The bright non-eclipsing star resides at the cluster turnoff, and ultimately its mass will directly constrain the turnoff mass: our preliminary determination is MA = 1.251 ± 0.057 M⊙. A careful examination of the light curves indicates that the fainter star in the eclipsing binary undergoes a very brief period of total eclipse, which enables us to precisely decompose the light of the three stars and place them in the color-magnitude diagram (CMD). We also present improved analysis of two previously discussed detached eclipsing stars in NGC 6819 (WOCS 40007 and WOCS 23009) en route to a combined determination of the cluster’s distance modulus (m - M)V = 12.38 ± 0.04. Because this paper significantly increases the number of measured stars in the cluster, we can better constrain the age of the CMD to be 2.21 ± 0.10 ± 0.20 Gyr. Additionally, using all measured eclipsing binary star masses and radii, we constrain the age to 2.38 ± 0.05 ± 0.22 Gyr. The quoted uncertainties are estimates of measurement and systematic uncertainties (due to model physics differences and metal content), respectively. This is paper 57 of the WIYN Open Cluster Study (WOCS).

  11. Detection of a tertiary companion in the eclipsing binary AD Andromeda

    NASA Astrophysics Data System (ADS)

    Liao, Wenping; Qian, Shengbang

    2009-04-01

    New orbital period variation of the eclipsing binary, AD Andromeda, was analyzed based on one CCD photometric times of minimum we have obtained and all available photoelectric and CCD values collected from the literatures. It is discovered that the orbital period of the binary shows a periodic oscillation with a period of 14.38 years and an amplitude of 0.0186 days. The periodic oscillation can be explained by the light-time effect via the presence of a tertiary component in a nearly circular orbit with a small eccentricity of e = 0.30 in the system. Based on the present analysis, it is estimated that the mass of the third body is no less than 1.76(±0.08)M⊙, and it should contribute light to the total system. Meanwhile, the photoelectric light curve obtained in yellow light by Ruciński [Ruciński, S.M., 1966. AcA 16, 307] was reanalyzed with the 2003 version of the W-D code. The results show that AD Andromeda is a detached eclipsing binary, and photometric solutions were computed. Based on the analysis, we obtained a small amount of third light in the system (L3V˜0.001), which is too small for the contribution of the tertiary companion star. The low luminosity of the third companion may be explained in two possible ways, either: (1) the third companion might itself be a close double star consisting of two stars of 0.88 solar masses, or (2) it is a dark star such as a neutron star. We think the first possibility is a more likely one than a neutron star companion. New photometric and spectroscopic observations and a detailed investigation of those data are urgently required in the future.

  12. 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.

  13. The Eclipsing Binary Di Herculis: One Mystery Solved, But Another Takes Its Place

    NASA Astrophysics Data System (ADS)

    Zimmerman, Nicole; Guinan, E.; Maloney, F.

    2010-01-01

    The 8th-mag eclipsing binary DI Herculis has perplexed scientists for the past few decades due to its anomalously slow apsidal motion rate. DI Her consists of two main-sequence stars (B5V, B6V), with P(orb) = 10.55 days, and eccentricity(e= 0.489). Since the apsidal motion is dominated by General Relativity, the system is one of the few tests available for verifying the theory. Combining the expected classical (1.93°/100 yr) and relativistic (2.34°/100 yr) effects, the predicted apsidal motion rate is 4.27°/100 yr. Our recent determination of the apsidal motion yields 1.33°+/-0.25 /100 yr, based on eclipse timings from 1936-2008. Recently, Albrecht et al (2009, Nature 461) have apparently solved the apsidal motion anomaly of DI Her, finding that the axes of both stars are significantly inclined from the normal to the orbital plane. This was determined from the radial velocity curves and observing the Rossiter-McLaughlin effect during primary and secondary eclipses. Having significantly misaligned axes of rotation produces a perturbation that greatly reduces the classical apsidal motion effect, thus explaining the observed small apsidal motion rate. Even though this discovery apparently solves the problem, it raises new questions as to how the axes are so tilted. Additionally, tilted axes are expected to contribute to other orbital effects, such as changes in orbital inclination, which have not yet observed from the apparent constancy in eclipse depths over time. We have also searched for evidence of small periodic oscillations in the eclipse timings and found no evidence of a light travel time effect arising from a possible tertiary component. Further, we find evidence that the projected rotation axes of the stars may be precessing, since it appears that the value of V(rot)sini has increased over the past 30 years. This research was supported by NSF/RUI Grants AST05-07536/42.

  14. Eclipsing binary stars in the Large Magellanic Cloud: results from the EROS-2, OGLE and VMC surveys

    NASA Astrophysics Data System (ADS)

    Muraveva, T.; Clementini, G.; Maceroni, C.; Evans, C. J.; Moretti, M. I.; Cioni, M.-R. L.; Marquette, J. B.; Ripepi, V.; de Grijs, R.; Groenewegen, M. A. T.; Piatti, A. E.; van Loon, J. Th.

    2014-09-01

    We present a catalogue of 1768 eclipsing binary stars (EBs) detected in the Large Magellanic Cloud (LMC) by the second generation of the EROS survey (hereinafter EROS-2); 493 of them are new discoveries located in outer regions (out of the central bar) of the LMC. These sources were originally included in a list of candidate classical Cepheids (CCs) extracted from the EROS-2 catalogue on the basis of the period (0.89 < PEROS < 15.85 d) versus luminosity [13.39 < < 17.82 mag] diagram. After visual inspection of the light curves we reclassified them as eclipsing binaries. They have blue colours (BEROS - REROS < 0.2 mag) hence we classed them as hot eclipsing binaries (HEBs) containing hot massive components: main sequence (MS) stars or blue giants. We present Ks-band light curves for 999 binaries from our sample that have a counterpart in the VISTA near-infrared ESO public survey of the Magellanic Clouds system (VMC). We provide spectral classifications of 13 HEBs with existing spectroscopy. We divided our sample into contact-like binaries and detached/semi-detached systems based on both visual inspection and the parameters of the Fourier decomposition of the light curves and analysed the period-luminosity (PL) relations of the contact-like systems using the REROS and Ks magnitudes at maximum light. The contact-like binaries in our sample do not follow PL relations. We analysed the sample of contact binaries from the OGLE III catalogue and confirmed that PLI and PL_{K_s} sequences are defined only by eclipsing binaries containing a red giant component.

  15. Orbital and physical parameters of eclipsing binaries from the ASAS catalogue - VIII. The totally eclipsing double-giant system HD 187669

    NASA Astrophysics Data System (ADS)

    Hełminiak, K. G.; Graczyk, D.; Konacki, M.; Pilecki, B.; Ratajczak, M.; Pietrzyński, G.; Sybilski, P.; Villanova, S.; Gieren, W.; Pojmański, G.; Konorski, P.; Suchomska, K.; Reichart, D. E.; Ivarsen, K. M.; Haislip, J. B.; LaCluyze, A. P.

    2015-04-01

    We present the first full orbital and physical analysis of HD 187669, recognized by the All-Sky Automated Survey (ASAS) as the eclipsing binary ASAS J195222-3233.7. We combined multi-band photometry from the ASAS and SuperWASP public archives and 0.41-m PROMPT robotic telescopes with our high-precision radial velocities from the HARPS spectrograph. Two different approaches were used for the analysis: (1) fitting to all data simultaneously with the WD code and (2) analysing each light curve (with JKTEBOP) and radial velocities separately and combining the partial results at the end. This system also shows a total primary (deeper) eclipse, lasting for about 6 d. A spectrum obtained during this eclipse was used to perform atmospheric analysis with the MOOG and SME codes to constrain the physical parameters of the secondary. We found that ASAS J195222-3233.7 is a double-lined spectroscopic binary composed of two evolved, late-type giants, with masses of M1 = 1.504 ± 0.004 and M2 = 1.505 ± 0.004 M⊙, and radii of R1 = 11.33 ± 0.28 and R2 = 22.62 ± 0.50 R⊙. It is slightly less metal abundant than the Sun, and has a P = 88.39 d orbit. Its properties are well reproduced by a 2.38-Gyr isochrone, and thanks to the metallicity estimation from the totality spectrum and high precision of the masses, it was possible to constrain the age down to 0.1 Gyr. It is the first so evolved Galactic eclipsing binary measured with such good accuracy, and as such it is a unique benchmark for studying the late stages of stellar evolution.

  16. Comment on the Radius of the Cooler Component of the Eclipsing RS CVn Binary CF Tuc (HD 5303)

    NASA Astrophysics Data System (ADS)

    Coates, D. W.; Thompson, K.; Innis, J. L.

    2000-12-01

    The value of rotational v sin i for the cooler star in the eclipsing RS CVn binary CF Tuc deduced from high-resolution spectroscopy and least-squares deconvolution by Donati et al. (1997) appears to be too high when compared to the radius obtained from the light-curve solution. We suggest that this case be studied further.

  17. Erratum: "B.R.N.O. Contributions #38 Times of minima of eclipsing binary" (OEJV #160, [2013])

    NASA Astrophysics Data System (ADS)

    Honková, K.; Juryšek, J.; Lehký, M.; Šmelcer, L.; Trnka, J.; Mašek, M.; Urbaník, M.; Auer, R.; Vrašták, M.; Kučáková, H.; Ruocco, N.; Magris, M.; Polák, J.; Brát, L.; Audejean, M.; Banfi, M.; Moudrá, M.; Lomoz, F.; Přibík, V.; Dřevěný, R.; Scaggiante, F.; Kocián, R.; Cagaš, P.; Poddaný, S.; Zíbar, M.; Jacobsen, J.; Marek, P.; Colazo, C.; Zardin, D.; Sobotka, P.; Starzomski, J.; Hladík, B.; Vincenzi, M.; Skarka, M.; Walter, F.; Chapman, A.; Díaz, N. D.; Aceti, P.; Singh, P.; Kalista, L.; Kamenec, M.; Zejda, M.; Marchi, F.; Bílek, R.; Guzzo, P.; Corfini, G.; Onderková, K.; Hečko, A.; Mina, F.; Vítek, M.; Barsa, R.; Quinones, C.; Taormina, M.; Melia, R.; Schneiter, M.; Scavuzzo, A.; Marcionni, N.; Ehrenberger, R.; Tapia, L.; Fasseta, G.; Suarez, N.; Scaggiante, D.; Artusi, E.; Garcia, R.; Grnja, J.; Fišer, A.; Hynek, T.; Vilášek, M.; Rozehnal, J.; Kalisch, T.; Lang, K.; Gorková, S.; Novysedlák, R.; Salvaggio, F.; Smyčka, T.; Spurný, M.; Wikander, T.; Mravik, J.; Šuchań, J.; Čaloud, J.

    2014-08-01

    Due to an errors in calculated heliocentric corrections, there are 404 wrong HJD minima timings (with larger Difference than Min error; see header of the Table) in "B.R.N.O. Contributions #38 Times of minima of eclipsing binary" paper. The correct minima timings are presented hereafter.

  18. THE DISTANCE TO THE MASSIVE ECLIPSING BINARY LMC-SC1-105 IN THE LARGE MAGELLANIC CLOUD

    SciTech Connect

    Bonanos, Alceste Z.; Castro, Norberto; Macri, Lucas M.; Kudritzki, Rolf-Peter E-mail: norberto@noa.gr E-mail: kud@ifa.hawaii.edu

    2011-03-01

    This Letter presents the first distance measurement to the massive, semi-detached, eclipsing binary LMC-SC1-105, located in the LH 81 association of the Large Magellanic Cloud (LMC). Previously determined parameters of the system are combined with new near-infrared photometry and a new temperature analysis to constrain the reddening toward the system, and determine a distance of 50.6 {+-} 1.6 kpc (corresponding to a distance modulus of 18.52 {+-} 0.07 mag), in agreement with previous eclipsing binary measurements. Although this is the sixth distance measurement to an eclipsing binary in the LMC, it is the first to an O-type system. We thus demonstrate the suitability of O-type eclipsing binaries (EBs) as distance indicators. We suggest using bright, early-type EBs to measure distances along different sight lines, as an independent way to map the depth of the LMC and resolve the controversy about its three-dimensional structure.

  19. M33 X-7: ChASeM33 Reveals the First Eclipsing Black Hole X-Ray Binary

    NASA Astrophysics Data System (ADS)

    Pietsch, W.; Haberl, F.; Sasaki, M.; Gaetz, T. J.; Plucinsky, P. P.; Ghavamian, P.; Long, K. S.; Pannuti, T. G.

    2006-07-01

    The first observations conducted as part of the Chandra ACIS survey of M33 (ChASeM33) sampled the eclipsing X-ray binary M33 X-7 over a large part of the 3.45 day orbital period and have resolved eclipse ingress and egress for the first time. The occurrence of the X-ray eclipse allows us to determine an improved ephemeris of mid-eclipse and binary period as HJD (2,453,639.119+/-0.005)+/-N(3.453014+/-0.000020) and constrain the eclipse half-angle to 26.5d+/-1.1d. There are indications for a shortening of the orbital period. The X-ray spectrum is best described by a disk blackbody spectrum typical for black hole X-ray binaries in the Galaxy. We find a flat power density spectrum, and no significant regular pulsations were found in the frequency range of 10-4 to 0.15 Hz. HST WFPC2 images resolve the optical counterpart, which can be identified as an O6 III star with the help of extinction and color corrections derived from the X-ray absorption. Based on the optical light curve, the mass of the compact object in the system most likely exceeds 9 Msolar. This mass, the shape of the X-ray spectrum, and the short-term X-ray time variability identify M33 X-7 as the first eclipsing black hole high-mass X-ray binary.

  20. ON THE FORMATION OF THE PECULIAR LOW-MASS X-RAY BINARY IGR J17480-2446 IN TERZAN 5

    SciTech Connect

    Jiang Long; Li Xiangdong

    2013-07-20

    IGR J17480-2446 is an accreting X-ray pulsar in a low-mass X-ray binary harbored in the Galactic globular cluster Terzan 5. Compared with other accreting millisecond pulsars, IGR J17480-2446 is peculiar for its low spin frequency (11 Hz), which suggests that it might be a mildly recycled neutron star at the very early phase of mass transfer. However, this model seems to be in contrast with the low field strength deduced from the kilo-Hertz quasi-periodic oscillations observed in IGR J17480-2446. Here, we suggest an alternative interpretation, assuming that the current binary system was formed during an exchange encounter either between a binary (which contains a recycled neutron star) and the current donor, or between a binary and an isolated, recycled neutron star. In the resulting binary, the spin axis of the neutron star could be parallel or anti-parallel with the orbital axis. In the latter case, the abnormally low frequency of IGR J17480-2446 may result from the spin-down to spin-up evolution of the neutron star. We also briefly discuss the possible observational implications of the pulsar in this scenario.

  1. Dynamical analyses of the companions orbiting eclipsing binaries - I. SW Lacertae

    NASA Astrophysics Data System (ADS)

    Yuan, Jinzhao; Şenavci, Hakan Volkan

    2014-03-01

    New mid-eclipse times of the short-period eclipsing binary SW Lacertae are reported, and two cyclical variations are found in the corresponding O - C diagram. The proposed light-travel time model is refined. The best fit suggests that two possible circumbinary companions are in a near 3:1 mean-motion resonance with periods of 27.01 and 82.61 yr. Based on the best-fitting solution, we have studied the stabilities of the two companions moving on a series of mutually inclined orbits. The results show that no orbital configurations can survive for >1000 yr. Then, non-Keplerian corrections to the initial conditions and the more distant K-dwarf companion discovered by Ruciński, Pribulla & van Kerkwijk, moving on assumed circular orbits with wide ranges of orbital inclinations, are considered in our numerical simulations. The outcome similarly reveals that the whole system is yet short-term unstable. Perhaps, one or both cyclical variations in the mid-eclipse times are attributed to irregular mass exchange and/or magnetic cycles in the magnetically active W UMa system. Despite this, the instability of the system may also arise from the large uncertainties in orbital parameters. So, secular observations of this target are needed to determine the eccentricity of the outmost companion and the orbital period of the middle companion with much higher precision. Our results suggest that, if the two inner companions do exist, they should be on mutually inclined orbits of >100°, with the minimum masses of 0.62 and 1.94 M⊙ for the innermost and middle components, respectively. Our work demonstrates that it is important and necessary to perform dynamical analyses before a discovery of two or more circumbinary companions is announced.

  2. Eclipse timing variations to detect possible Trojan planets in binary systems

    NASA Astrophysics Data System (ADS)

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

    2015-11-01

    This paper is devoted to study the circumstances favourable to detect Trojan planets in close binary star systems by the help of eclipse timing variations (ETVs). 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 like PLATO, TESS and CHEOPS), we investigated the dynamics of binary star systems with a planet in tadpole motion. We did numerical simulations by using the full three-body problem as a dynamical model. The stability and the ETVs are investigated by computing stability/ETV maps for different masses of the secondary star and the Trojan planet. In addition, we changed the eccentricity of the possible Trojan planet. By the help of the libration amplitude σ, we could show whether or not all stable objects are moving in tadpole orbits. We can conclude that many amplitudes of ETVs are large enough to detect Earth-like Trojan planets in binary star systems. As an application, we prepared a list of possible candidates.

  3. Time-resolved spectroscopy and photometry of the eclipsing AM Herculis binary EXO 033319 - 2554. 2

    SciTech Connect

    Allen, R.G.; Berriman, G.; Smith, P.S.; Schmidt, G.D. )

    1989-12-01

    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. 13 refs.

  4. LONG-TERM PHOTOMETRIC BEHAVIOR OF THE ECLIPSING BINARY GW CEPHEI

    SciTech Connect

    Lee, Jae Woo; Youn, Jae-Hyuck; Han, Wonyong; Lee, Chung-Uk; Kim, Seung-Lee; Kim, Ho-Il; Park, Jang-Ho; Koch, Robert H. E-mail: jhyoon@kasi.re.kr E-mail: leecu@kasi.re.kr E-mail: hikim@kasi.re.kr E-mail: rhkoch@earthlink.net

    2010-03-15

    New CCD photometry over four successive years from 2005 is presented for the eclipsing binary GW Cep, together with reasonable explanations for the light and period variations. All historical light curves, obtained over a 30 yr interval, display striking light changes, and are best modeled by the simultaneous existence of a cool spot and a hot spot on the more massive cool component star. The facts that the system is magnetically active and that the hot spot has consistently existed on the inner hemisphere of the star indicate that the two spots are formed by (1) magnetic dynamo-related activity on the cool star and (2) mass transfer from the primary to the secondary component. Based on 38 light-curve timings from the Wilson-Devinney code and all other minimum epochs, a period study of GW Cep reveals that the orbital period has experienced a sinusoidal variation with a period and semi-amplitude of 32.6 yr and 0.009 days, respectively. In principle, these may be produced either by a light-travel-time effect due to a third body or by an active magnetic cycle of at least one component star. Because we failed to find any connection between luminosity variability and the period change, that change most likely arises from the existence of an unseen third companion star with a minimum mass of 0.22 M {sub sun} gravitationally bound to the eclipsing pair.

  5. A circumbinary planet in orbit around the short-period white dwarf eclipsing binary RR Cae

    NASA Astrophysics Data System (ADS)

    Qian, S.-B.; Liu, L.; Zhu, L.-Y.; Dai, Z.-B.; Fernández Lajús, E.; Baume, G. L.

    2012-05-01

    By using six newly determined mid-eclipse times together with those collected from the literature, we have found that the observed minus calculated (O-C) curve of RR Cae shows a cyclic change with a period of 11.9 yr and an amplitude of 14.3 s while it undergoes an upward parabolic variation [revealing a long-term period increase at a rate of ?]. The cyclic change was analysed for the light-travel-time effect that arises from the gravitational influence of a third companion. The mass of the third body was determined to be M3sin i'= 4.2(± 0.4) MJup, suggesting that it is a circumbinary giant planet when its orbital inclination is larger than 17?6. The orbital separation of the circumbinary planet from the central eclipsing binary is about 5.3(± 0.6) au. The period increase is opposite to the changes caused by angular momentum loss via magnetic braking or/and gravitational radiation; and it cannot be explained by the mass transfer between both components because of its detached configuration. These indicate that the observed upward parabolic change is only a part of a long-period (longer than 26.3 yr) cyclic variation, which may reveal the presence of another giant circumbinary planet in a wide orbit.

  6. HS 0705+6700: a New Eclipsing sdB Binary

    NASA Astrophysics Data System (ADS)

    Drechsel, H.; Heber, U.; Napiwotzki, R.; Ostensen, R.; Solheim, J.-E.; Deetjen, J.; Schuh, S.

    HS 0705+6700 is a newly discovered eclipsing sdB binary system consisting of an sdB primary and a cool secondary main sequence star. CCD photometry obtained in October and November 2000 with the 2.5m Nordic (NOT) telescope (La Palma, Tenerife) in the B passband and with the 2.2m Calar Alto telescope (CAFOS, R filter) yielded eclipse light curves with complete orbital phase coverage at high time resolution. A periodogram analysis of 12 primary minimum times distributed over the time span from October 2000 to March 2001 allowed to derive the following exact period and linear ephemeris: prim. min. = HJD 2451822.759782(22) + 0.09564665(39) ṡ E A total of 15 spectra taken with the 3.5m Calar Alto telescope (TWIN spectrograph) on March 11-12, 2001, were used to establish the radial velocity curve of the primary star (K1 = 85.8 km/s) , and to determine its basic atmospheric parameters (Teff = 29300 K, log g = 5.47). The B and R light curves were solved using our Wilson-Devinney based light curve analysis code MORO (Drechsel et al. 1995, A&A 294, 723). The best fit solution yielded exact system parameters consistent with the spectroscopic results. Detailed results will be published elsewhere (Drechsel et al. 2001, A&A, in preparation).

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

    SciTech Connect

    Hong, Kyeongsoo; Lee, Chung-Uk; Kim, Seung-Lee; Kang, Young-Woon

    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 from 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.

  8. Short Apsidal Period of Three Eccentric Eclipsing Binaries Discovered in the Large Magellanic Cloud

    NASA Astrophysics Data System (ADS)

    Hong, Kyeongsoo; Lee, Chung-Uk; Kim, Seung-Lee; Kang, Young-Woon

    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 from 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.

  9. A Chandra Observation of the Eclipsing Wolf-Rayet Binary CQ Cep

    NASA Astrophysics Data System (ADS)

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

    2015-01-01

    The short-period (1.64 day) near-contact eclipsing WN6+O9 binary system CQ Cep provides an ideal laboratory for testing the predictions of X-ray colliding wind shock theory at close separation where the winds may not have reached terminal speeds before colliding. We present results of a Chandra X-ray observation of CQ Cep spanning one day during which a simultaneous Chandra optical light curve was acquired. Our primary objective was to compare the observed X-ray properties with colliding wind shock theory, which predicts that the hottest shock plasma (T > 20 MK) will form on or near the line-of-centers between the stars. The X-ray spectrum is strikingly similar to apparently single WN6 stars such as WR 134 and spectral lines reveal plasma over a broad range of temperatures T ~ 4 - 40 MK. A deep optical eclipse was seen as the O star passed in front of the Wolf-Rayet star but, surprisingly, no significant X-ray variability was detected. Because of the high inclination orbit, this implies that the hottest X-ray plasma is not confined to the region between the stars, at odds with the colliding wind shock picture. We will summarize the Chandra results in the context of predictions from colliding wind theory.

  10. kHz Quasiperiodic Oscillations in Low-Mass X-Ray Binaries as Probes of General Relativity in the Strong-Field Regime

    NASA Astrophysics Data System (ADS)

    Stella, Luigi; Vietri, Mario

    1999-01-01

    We consider the interpretation of a pair of kHz quasiperiodic oscillations (QPOs) in the Fourier spectra of two low-mass x-ray binaries, Sco X-1 and 4U1608-52, hosting an old accreting neutron star. The observed frequency difference of these QPOs decreases as their frequency increases, contrary to simple beat frequency models. We show that the behavior of these QPOs is instead well matched in terms of the fundamental frequencies for test particle motion in the gravitational field of the neutron star, for reasonable star masses, and nearly independent of the star spin. These results are not reproduced through the post-Newtonian approximation of general relativity. kHz QPOs from x-ray binaries likely provide an accurate laboratory for strong-field general relativity.

  11. KHz Quasi Periodic Oscillations in Low Mass X-ray Binaries as Probes of General Relativity in the Strong Field Regime

    NASA Astrophysics Data System (ADS)

    Stella, Luigi; Vietri, Mario

    1998-12-01

    The pair of kHz Quasi Periodic Oscillations (QPOs) in the Fourier spectra of two low mass X-ray binaries, Sco X-1 and 4U1608-52, hosting an old accreting neutron star, display a frequency difference that decreaseas for increasing QPO frequency. This is contrary to simple beat frequency models, which predict a constant frequency difference. We show that the behaviour of these QPOs is well matched in terms of the fundamental (radial and azimuthal) frequencies for test particle motion in the vicinity the neutron star, for reasonable star masses, and nearly independent of the star spin. The radial frequency must be much smaller than the azimuthal one, testifying that kHz QPOs originate from close to the innermost stable orbit. These results are not reproduced through the post-Newtonian approximation of General Relativity (GR). kHz QPOs from X-ray binaries likely provide an accurate laboratory for strong field GR.

  12. Investigation of O-C Changes in a Sample of Eclipsing Binary Systems

    NASA Astrophysics Data System (ADS)

    Jableka, D.; Zola, S.; Kreiner, J. M.; Zakrzewski, B.

    In this work we present results of analysis of the O-C behaviour for 79 eclipsing binary systems selected from the Kreiner's database. These systems show long time scale, possibly cyclic, modulations of their orbital periods on the timescale of a few years to several decades. We consider two possibilities to explain the observed O-C changes: (1) the Light Time Travel Effect due to the presence of a third body in the system, and (2) the Applegate effect, in which orbital period modulation is caused by cyclic changes of gravitational quadrupole momentum when a star goes through its magnetic activity cycles. Within the former explanation, the orbital parameters of a hypothetical third body are fitted using the Monte Carlo method and the lower mass limit for the third companion is calculated. As a result, we derived that in 21 cases the mass of the third body exceeds the Neutron Star mass limit.

  13. Radial Velocity and Light Curve Analysis of the Eclipsing Binary Nn Vir

    NASA Astrophysics Data System (ADS)

    Pazhouhesh, R.; Melendo, E. G.

    2005-04-01

    The eclipsing binary NN Vir is a short period system showing an EW-type light curve. Photometric observations of NN Vir were done by Gomez Ferrellad and Garcia Melendo (1997) at Esteve Duran Observatory. The first spectroscopic observations of this system were obtained by Rucinski and Lu (1999). The radial velocity and light curves analysis was made with the latest version of the Wilson program (1998), and the geometric and physical elements of the system are derived. From the simultaneous solutions of the system, we determined the masses and radii of the components: 1.89 M ⊙ and 1.65 R ⊙ for the primary component; 0.93 M ⊙ and 1.23 R ⊙ for the secondary component. We estimated effective temperatures of 7030 K for the primary and 6977 K for the secondary component.

  14. Time-series Spectroscopy of the Pulsating Eclipsing Binary XX Cephei

    NASA Astrophysics Data System (ADS)

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

    2016-03-01

    Oscillating Algol-type eclipsing binaries (oEA) are very interesting objects that have three observational features of eclipse, pulsation, and mass transfer. Direct measurement of their masses and radii from the double-lined radial velocity data and photometric light curves would be the most essential for understanding their evolutionary process and for performing the asteroseismological study. We present the physical properties of the oEA star XX Cep from high-resolution time-series spectroscopic data. The effective temperature of the primary star was determined to be 7946 ± 240 K by comparing the observed spectra and the Kurucz models. We detected the absorption lines of the secondary star, which had never been detected in previous studies, and obtained the radial velocities for both components. With the published BVRI light curves, we determined the absolute parameters for the binary via Wilson-Devinney modeling. The masses and radii are {M}1=2.49+/- 0.06 {M}⊙ , {M}2=0.38+/- 0.01 {M}⊙ , {R}1=2.27+/- 0.02 {R}⊙ , and {R}2=2.43+/- 0.02 {R}⊙ , respectively. The primary star is about 45% more massive and 60% larger than the zero-age main sequence stars with the same effective temperature. It is probably because XX Cep has experienced a very different evolutionary process due to mass transfer, contrasting with the normal main sequence stars. The primary star is located inside the theoretical instability strip of δ Sct-type stars on the HR diagram. We demonstrated that XX Cep is an oEA star, consisting of a δ Sct-type pulsating primary component and an evolved secondary companion.

  15. The Araucaria Project: High-precision orbital parallax and masses of the eclipsing binary TZ Fornacis

    NASA Astrophysics Data System (ADS)

    Gallenne, A.; Pietrzyński, G.; Graczyk, D.; Konorski, P.; Kervella, P.; Mérand, A.; Gieren, W.; Anderson, R. I.; Villanova, S.

    2016-02-01

    Context. Independent distance estimates are particularly useful to check the precision of other distance indicators, while accurate and precise masses are necessary to constrain evolution models. Aims: The goal is to measure the masses and distance of the detached eclipsing-binary TZ For with a precision level lower than 1% using a fully geometrical and empirical method. Methods: We obtained the first interferometric observations of TZ For with the VLTI/PIONIER combiner, which we combined with new and precise radial velocity measurements to derive its three-dimensional orbit, masses, and distance. Results: The system is well resolved by PIONIER at each observing epoch, which allowed a combined fit with eleven astrometric positions. Our derived values are in a good agreement with previous work, but with an improved precision. We measured the mass of both components to be M1 = 2.057 ± 0.001 M⊙ and M2 = 1.958 ± 0.001 M⊙. The comparison with stellar evolution models gives an age of the system of 1.20 ± 0.10 Gyr. We also derived the distance to the system with a precision level of 1.1%: d = 185.9 ± 1.9 pc. Such precise and accurate geometrical distances to eclipsing binaries provide a unique opportunity to test the absolute calibration of the surface brightness-colour relation for late-type stars, and will also provide the best opportunity to check on the future Gaia measurements for possible systematic errors. Based on observations made with ESO telescopes at Paranal observatory under program IDs 094.D-0320.The calibrated interferometric data as OIFITS files are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/586/A35

  16. A Class Exercise: Studying the Eclipsing Binary Star RZ Cas Through Visual Observations

    NASA Astrophysics Data System (ADS)

    Balonek, T. J.; Davis, S. M.

    2000-05-01

    As part of the sophomore-junior level "Astronomical Techniques" course at Colgate University, students learn just how much science they can do with simple tools: a pair of binoculars, a clock, and pencil and paper. The students study the Algol type visual eclipsing binary star system RZ Cassiopeiae: observing and making a light curve for the primary minimum, determining the time of minimum using several techniques, calculating the binary star system's orbital period, and determining changes in the system's period over a thirty year interval by constructing an O-C curve. Through a series of preparatory exercises, the students learn how to read star maps and use the unaided eye, binoculars and telescopes to locate star fields and make visual magnitude measurements. By making multiple measurements of stars in the field of RZ Cas on several nights, the students determine the accuracy they can achieve in estimating the visual magnitude of a star -- typically 0.2 magnitude. (Some students even accidentally discover that one of the stars in the field is a variable star!) With this experience, the students use binoculars to observe the four hour primary eclipse of RZ Cas (magnitude 6.2 - 7.7), making magnitude measurements every five minutes. A light curve is then plotted. Several methods are used to determine the time of minimum, which is then converted to heliocentric Julian day. Using times of minima determined by former students (and the instructor) in previous years dating from 1968 to the present, the students determine the average period to a tenth of a second second. By constructing an O-C curve from the class's data and that obtained by the AAVSO, changes in the period of RZ Cas are noticeable -- possibly due to mass transfer in the system. It will be interesting for future classes to build on this knowledge using the primitive tools of our not so distant past.

  17. Implications for planet formation from population inference of Kepler-planet-candidates and eclipsing binaries

    NASA Astrophysics Data System (ADS)

    Shabram, Megan Iris

    The Kepler Space Science Mission has revolutionized our understanding of planetary system architectures, and the diversity of planet bulk densities. From Kepler, we now have a population of ˜4,700 planet candidates and ˜ 3000 eclipsing binaries with measured light curves, from which we can begin to characterize the distribution of stars and planets to tease out relationships between planet properties and host star properties in a robust statistical manner. The results of these investigations constrain proposed planet formation theories. This dissertation analyzes three particular sub-populations observed by Kepler that are well suited for hierarchical inference to characterize their population properties. First, we investigate the eccentricity distribution for a sample of short-period planet candidates from Kepler, where both the transit and occultation are observed for each system. This subsample lends a rare opportunity for tractable inference of its eccentricity distribution, exposing at least two populations within the eccentricity distribution and potential correlations of the eccentricity with host star metallicity and planet radius. Secondly, we investigate the mass-radius-eccentricity relation for a sample of near-resonant planet-pairs from Kepler. This study greatly improves upon previous research of constraining the mass-radius relation for small planets. Furthermore, we explore the period-eccentricity distribution of eclipsing binary stars from Kepler. We find that ˜ 72% of EBs below ˜ 11 days are very circularized, where as ˜ 87% of EBs above ˜ 11 days can take on a wide range in eccentricity values including some with significant eccentricities.

  18. A New sdO+dM Binary with Extreme Eclipses and Reflection Effect

    NASA Astrophysics Data System (ADS)

    Derekas, A.; Németh, P.; Southworth, J.; Borkovits, T.; Sárneczky, K.; Pál, A.; Csák, B.; Garcia-Alvarez, D.; Maxted, P. F. L.; Kiss, L. L.; Vida, K.; Szabó, Gy. M.; Kriskovics, L.

    2015-08-01

    We report the discovery of a new totally eclipsing binary (R.A. = {06}{{h}}{40}{{m}}{29}{{s}}11; decl. = +38°56‧52″2 J = 2000.0; Rmax = 17.2 mag) with an sdO primary and a strongly irradiated red dwarf companion. It has an orbital period of Porb = 0.187284394(11) day and an optical eclipse depth in excess of 5 mag. We obtained 2 low-resolution classification spectra with GTC/OSIRIS and 10 medium-resolution spectra with WHT/ISIS to constrain the properties of the binary members. The spectra are dominated by H Balmer and He ii absorption lines from the sdO star, and phase-dependent emission lines from the irradiated companion. A combined spectroscopic and light curve analysis implies a hot subdwarf temperature of Teff(spec) = 55,000 ± 3000 K, surface gravity of log g (phot) = 6.2 ± 0.04 (cgs), and a He abundance of {log}(n{He}/n{{H}})=-2.24+/- 0.40. The hot sdO star irradiates the red dwarf companion, heating its substellar point to about 22,500 K. Surface parameters for the companion are difficult to constrain from the currently available data: the most remarkable features are the strong H Balmer and C ii-iii lines in emission. Radial velocity estimates are consistent with the sdO+dM classification. The photometric data do not show any indication of sdO pulsations with amplitudes greater than 7 mmag, and Hα-filter images do not provide evidence for the presence of a planetary nebula associated with the sdO star.

  19. KIC 9246715: The Double Red Giant Eclipsing Binary with Odd Oscillations

    NASA Astrophysics Data System (ADS)

    Rawls, Meredith L.; Gaulme, Patrick; McKeever, Jean; Jackiewicz, Jason; Orosz, Jerome A.; Corsaro, Enrico; Beck, Paul G.; Mosser, Benoît; Latham, David W.; Latham, Christian A.

    2016-02-01

    We combine Kepler photometry with ground-based spectra to present a comprehensive dynamical model of the double red giant eclipsing binary KIC 9246715. While the two stars are very similar in mass ({M}1={2.171}-0.008+0.006 {M}⊙ , {M}2={2.149}-0.008+0.006 {M}⊙ ) and radius ({R}1={8.37}-0.07+0.03 {R}⊙ , {R}2={8.30}-0.03+0.04 {R}⊙ ), an asteroseismic analysis finds one main set of solar-like oscillations with unusually low-amplitude, wide modes. A second set of oscillations from the other star may exist, but this marginal detection is extremely faint. Because the two stars are nearly twins, KIC 9246715 is a difficult target for a precise test of the asteroseismic scaling relations, which yield M = 2.17 ± 0.14 M⊙ and R = 8.26 ± 0.18 R⊙. Both stars are consistent with the inferred asteroseismic properties, but we suspect the main oscillator is Star 2 because it is less active than Star 1. We find evidence for stellar activity and modest tidal forces acting over the 171 day eccentric orbit, which are likely responsible for the essential lack of solar-like oscillations in one star and weak oscillations in the other. Mixed modes indicate the main oscillating star is on the secondary red clump (a core-He-burning star), and stellar evolution modeling supports this with a coeval history for a pair of red clump stars. This system is a useful case study and paves the way for a detailed analysis of more red giants in eclipsing binaries, an important benchmark for asteroseismology.

  20. Combining Fits of The Optical Photometry and X-ray Spectra of the Low Mass X-ray Binary V1408 Aquilae.

    NASA Astrophysics Data System (ADS)

    Gomez, Sebastian; Mason, Paul A.; Robinson, Edward L.

    2015-01-01

    V1408 Aquilae is a binary system with a black hole primary accreting matter from a low mass secondary. We observed the system at the McDonald Observatory and collected 126 hours of high speed optical photometry on the source. We modeled the optical light curve using the XRbinary light curve synthesis software. The best fits to the optical light curve seem to suggest that the primary is a low mass black hole, however we cannot exclude some high mass solutions. Our models slightly favor a 3 solar mass primary at an inclination of about 13 degrees. In order to further constrain these parameters, and verify their validity we compared the fits of the optical light curve to fits to the X-ray spectra of the source. Using data from the Chandra Transmission Grating Catalog and Archive and the ISIS software analysis package we modeled the spectra of the source with a multi-temperature blackbody for a relativistic accretion disk around a spinning black hole and an additional photon power law component. The fits to the optical lightcurve and X-ray spectra are in agreement, from this we conclude that the case for V1408 Aql to be at a low inclination and harbor a low mass black hole is plausible.

  1. Binaries discovered by the SPY survey. VI. Discovery of a low mass companion to the hot subluminous planetary nebula central star EGB 5 - a recently ejected common envelope?

    NASA Astrophysics Data System (ADS)

    Geier, S.; Napiwotzki, R.; Heber, U.; Nelemans, G.

    2011-04-01

    Hot subdwarf B stars (sdBs) in close binary systems are assumed to be formed via common envelope ejection. According to theoretical models, the amount of energy and angular momentum deposited in the common envelope scales with the mass of the companion. That low mass companions near or below the core hydrogen-burning limit are able to trigger the ejection of this envelope is well known. The currently known systems have very short periods ≃0.1-0.3 d. Here we report the discovery of a low mass companion (M2 > 0.14 M⊙) orbiting the sdB star and central star of a planetary nebula EGB 5 with an orbital period of 16.5 d at a minimum separation of 23 R⊙. Its long period is only just consistent with the energy balance prescription of the common envelope. The marked difference between the short and long period systems will provide strong constraints on the common envelope phase, in particular if the masses of the sdB stars can be measured accurately. Due to selection effects, the fraction of sdBs with low mass companions and similar or longer periods may be quite high. Low mass stellar and substellar companions may therefore play a significant role for the still unclear formation of hot subdwarf stars. Furthermore, the nebula around EGB 5 may be the remnant of the ejected common envelope making this binary a unique system to study this short und poorly understood phase of binary evolution. Based on observations at the Paranal Observatory of the European Southern Observatory for programmes No. 167.H-0407(A) and 71.D-0383(A). Based on observations collected at the Centro Astronómico Hispano Alemán (CAHA) at Calar Alto, operated jointly by the Max-Planck Institut für Astronomie and the Instituto de Astrofísica de Andalucía (CSIC). Some of the data used in this work were obtained at the William Herschel Telescope (WHT) operated by the Isaac Newton Group of Telescopes (ING).

  2. A Variable Near-Infrared Counterpart to the Neutron-Star Low-Mass X-Ray Binary 4U 1705 - 440

    NASA Astrophysics Data System (ADS)

    Homan, Jeroen; Kaplan, David L.; van den Berg, Maureen; Young, Andrew J.

    2009-02-01

    We report the discovery of a near-infrared (NIR) counterpart to the persistent neutron-star low-mass X-ray binary 4U 1705 - 440, at a location consistent with its recently determined Chandra X-ray position. The NIR source is highly variable, with Ks -band magnitudes varying between 15.2 and 17.3 and additional J- and H-band observations revealing color variations. A comparison with contemporaneous X-ray monitoring observations shows that the NIR brightness correlates well with X-ray flux and X-ray spectral state. We also find possible indications of a change in the slope of the NIR/X-ray flux relation among different X-ray states. We discuss and test various proposed mechanisms for the NIR emission from neutron-star low-mass X-ray binaries and conclude that the NIR emission in 4U 1705 - 440 is most likely dominated by X-ray heating of the outer accretion disk and the secondary star. This paper includes data gathered with the 6.5 m Magellan Baade Telescope, located at Las Campanas Observatory, Chile, and the 4 m Blanco Telescope, located at CTIO, Chile.

  3. Phase lags of quasi-periodic oscillations across source states in the low-mass X-ray binary 4U 1636-53

    NASA Astrophysics Data System (ADS)

    de Avellar, Marcio G. B.; Méndez, Mariano; Altamirano, Diego; Sanna, Andrea; Zhang, Guobao

    2016-09-01

    While there are many dynamical mechanisms and models that try to explain the origin and phenomenology of the quasi-periodic oscillations (QPOs) seen in the X-ray light curves of low-mass X-ray binaries, few of them address how the radiative processes occurring in these extreme environments give rise to the rich set of variability features actually observed in these light curves. A step towards this end comes from the study of the energy and frequency dependence of the phase lags of these QPOs. Here we used a methodology that allowed us to study, for the first time, the dependence of the phase lags of all QPOs in the range of 1-1300 Hz detected in the low-mass X-ray binary 4U 1636-53 upon energy and frequency as the source changes its states as it moves through the colour-colour diagram. Our results suggest that within the context of models of up-scattering Comptonization, the phase lags dependences upon frequency and energy can be used to extract size scales and physical conditions of the medium that produces the lags.

  4. Ultraviolet observations of close-binary and pulsating nuclei of planetary nebulae; Winds and shells around low-mass supergiants; The close-binary nucleus of the planetary nebula HFG-1; A search for binary nuclei of planetary nebulae; UV monitoring of irregularly variable planetary nuclei; and The pulsating nucleus of the planetary nebula Lo 4

    NASA Technical Reports Server (NTRS)

    Bond, Howard E.

    1992-01-01

    A brief summary of the research highlights is presented. The topics covered include the following: binary nuclei of planetary nebulae; other variable planetary nuclei; low-mass supergiants; and other IUE-related research.

  5. An Atlas of O-C Diagrams of Eclipsing Binary Stars

    NASA Astrophysics Data System (ADS)

    Kreiner, Jerzy M.; Kim, Chun-Hwey; Nha, Il-Seong

    The Atlas contains data for 1,138 eclipsing binaries represented by 91,798 minima timings, collected from the usual international and local journals, observatory publications and unpublished minima. Among this source material there is a considerable representation of amateur astronomers. Some timings were found in the card-index catalogue of the Astronomical Observatory of the Jagiellonian University, Cracow. Stars were included in the Atlas provided that they satisfied 3 criteria: (1) at least 20 minima had been times; (2) these minima spanned at least 2,500 cycles; and (3) the 2,500 cycles represented no fewer than 40 years. Some additional stars not strictly satisfying these criteria were also included if useful information was available. For each star, the Atlas contains the (O-C) diagram calculated by the authors and a table of general information containing: binary characteristics; assorted catalogue numbers; the statistics of the collected minima timings; the light elements (light ephemeris); comments and literature references. All of the data and diagrams in the Atlas are also available in electronic form on the Internet at http://www.as.ap.krakow.pl/o- c".

  6. Predicting GAIA's Parallax Distance to the Cygnus OB2 Association with Eclipsing Binaries

    NASA Astrophysics Data System (ADS)

    Kiminki, Daniel C.; Kobulnicky, Henry A.; Vargas Álvarez, Carlos A.; Alexander, Michael J.; Lundquist, Michael J.

    2015-10-01

    The Cygnus OB2 Association is one of the nearest and largest collections of massive stars in the Galaxy. Situated at the heart of the “Cygnus X” complex of star-forming regions and molecular clouds, its distance has proven elusive owing to the ambiguous nature of kinematic distances along this ℓ ≃ 80° sightline and the heavy, patchy extinction. In an effort to refine the three-dimensional geometry of key Cygnus X constituents, we have measured distances to four eclipsing double-lined OB-type spectroscopic binaries that are probable members of Cyg OB2. We find distances of 1.33 ± 0.17, 1.32 ± 0.07, 1.44 ± 0.18, and 1.32 ± 0.13 kpc toward MT91 372, MT91 696, CPR2002 A36, and Schulte 3, respectively. We adopt a weighted average distance of 1.33 ± 0.06 kpc. This agrees well with spectrophotometric estimates for the Association as a whole and with parallax measurements of protostellar masers in the surrounding interstellar clouds, thereby linking the ongoing star formation in these clouds with Cyg OB2. We also identify Schulte 3C (O9.5V), a 4″ visual companion to the 4.75 day binary Schulte 3(A+B), as a previously unrecognized Association member.

  7. Surface activity and oscillation amplitudes of red giants in eclipsing binaries

    SciTech Connect

    Gaulme, P.; Jackiewicz, J.; Appourchaux, T.; Mosser, B.

    2014-04-10

    Among the 19 red-giant stars belonging to eclipsing binary systems that have been identified in Kepler data, 15 display solar-like oscillations. We study whether the absence of mode detection in the remaining 4 is an observational bias or possibly evidence of mode damping that originates from tidal interactions. A careful analysis of the corresponding Kepler light curves shows that modes with amplitudes that are usually observed in red giants would have been detected if they were present. We observe that mode depletion is strongly associated with short-period systems, in which stellar radii account for 16%-24% of the semi-major axis, and where red-giant surface activity is detected. We suggest that when the rotational and orbital periods synchronize in close binaries, the red-giant component is spun up, so that a dynamo mechanism starts and generates a magnetic field, leading to observable stellar activity. Pressure modes would then be damped as acoustic waves dissipate in these fields.

  8. The absolute parameters of the detached eclipsing binary V482 Per

    NASA Astrophysics Data System (ADS)

    Baştürk, Ö.; Zola, S.; Liakos, A.; Nelson, R. H.; Gazeas, K.; Özavcı, İ.; Yılmaz, M.; Şenavcı, H. V.; Zakrzewski, B.

    2015-11-01

    We present the results of a spectroscopic, photometric and orbital period variation analysis of the detached eclipsing binary V482 Per. We derived the absolute parameters of the system (M1 = 1.51 M⊙, M2 = 1.29 M⊙, R1 = 2.39 R⊙, R2 = 1.45 R⊙, L1 = 10.15 L⊙, L2 = 3.01 L⊙) for the first time in literature, based on an analysis of our own photometric and spectroscopic observations. We confirm the nature of the variations observed in the system's orbital period, suggested to be periodic by earlier works. A light time effect due to a physically bound, star-sized companion (M3 = 2.14 M⊙) on a highly eccentric (e = 0.83) orbit, seems to be the most likely cause. We argue that the companion can not be a single star but another binary instead. We calculated the evolutionary states of the system's components, and we found that the primary is slightly evolving after the main sequence, while the less massive secondary lies well inside it.

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

    NASA Astrophysics Data System (ADS)

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

    2016-10-01

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

  10. NSVS 1908107, an EB-type eclipsing binary in the open cluster NGC 869

    NASA Astrophysics Data System (ADS)

    Pan, Yang; Luo, Zhi-Quan; Zhang, Xiao-Bin; Deng, Li-Cai; Wang, Kun; Luo, Yang-Ping; Fang, Wei-Jing; Peng, Yin-Jiang; Sun, Jin-Jiang; Liu, Qi-Li; Zhou, Qiang

    2016-07-01

    We present a time-series BV CCD photometry for an EB-type eclipsing binary NSVS 1908107, a member of the young open cluster NGC 869. The photometric solution was obtained by using the 2003 version of the Wilson-Devinney code. It reveals that the system is a semi-detached binary with the secondary component filling its Roche lobe. The mass ratio was determined to be 0.059±0.001. With the physical parameters of the cluster, the masses, radii and luminosities of the two components of NSVS 1908107 are estimated to be M 1 = 10.34±2.29 M ⊙, R 1 = 4.65±0.34 R ⊙, L 1 = 8076±371 L ⊙ and M 2 = 0.61±0.13 M ⊙, R 2 = 2.40±0.17 R ⊙, L 2 = 1054±48 L ⊙ respectively. The results show that the secondary component could be a giant or subgiant star with the outer envelope being stripped.

  11. GU Monocerotis: A high-mass eclipsing overcontact binary in the young open cluster Dolidze 25

    NASA Astrophysics Data System (ADS)

    Lorenzo, J.; Negueruela, I.; Vilardell, F.; Simón-Díaz, S.; Pastor, P.; Méndez Majuelos, M.

    2016-05-01

    Context. The eclipsing binary GU Mon is located in the star-forming cluster Dolidze 25, which has the lowest metallicity measured in a Milky Way young cluster. Aims: GU Mon has been identified as a short-period eclipsing binary with two early B-type components. We set out to derive its orbital and stellar parameters. Methods: We present a comprehensive analysis, including B and V light curves and 11 high-resolution spectra, to verify the orbital period and determine parameters. We used the stellar atmosphere code FASTWIND to obtain stellar parameters and create templates for cross-correlation. We obtained a model to fit the light and radial-velocity curves using the Wilson-Devinney code iteratively and simultaneously. Results: The two components of GU Mon are identical stars of spectral type B1 V with the same mass and temperature. The light curves are typical of an EW-type binary. The spectroscopic and photometric analyses agree on a period of 0.896640 ± 0.000007 d. We determine a mass of 9.0 ± 0.6 M⊙ for each component and for temperatures of 28 000 ± 2000 K. Both values are consistent with the spectral type. The two stars are overfilling their respective Roche lobes, sharing a common envelope and, therefore the orbit is synchronised and circularised. Conclusions: The GU Mon system has a fill-out factor above 0.8, containing two dwarf B-type stars on the main sequence. The two stars are in a very advanced stage of interaction, with their extreme physical similarity likely due to the common envelope. The expected evolution of such a system very probably leads to a merger while still on the main sequence. Photometry tables 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/590/A45

  12. SuperWASP discovery and SALT confirmation of a semi-detached eclipsing binary that contains a δ Scuti star

    NASA Astrophysics Data System (ADS)

    Norton, A. J.; Lohr, M. E.; Smalley, B.; Wheatley, P. J.; West, R. G.

    2016-03-01

    Aims: We searched the SuperWASP archive for objects that display multiply periodic photometric variations. Methods: Specifically we sought evidence for eclipsing binary stars that display a further non-harmonically related signal in their power spectra. Results: The object 1SWASP J050634.16-353648.4 has been identified as a relatively bright (V ~ 11.5) semi-detached eclipsing binary with a 5.104 d orbital period that displays coherent pulsations with a semi-amplitude of 65 mmag at a frequency of 13.45 d-1. Follow-up radial velocity spectroscopy with the Southern African Large Telescope confirmed the binary nature of the system. Using the phoebe code to model the radial velocity curve with the SuperWASP photometry enabled parameters of both stellar components to be determined. This yielded a primary (pulsating) star with a mass of 1.73 ± 0.11 M⊙ and a radius of 2.41 ± 0.06 R⊙, as well as a Roche-lobe filling secondary star with a mass of 0.41 ± 0.03 M⊙ and a radius of 4.21 ± 0.11 R⊙. Conclusions: 1SWASP J050634.16-353648.4 is therefore a bright δ Sct pulsator in a semi-detached eclipsing binary with one of the largest pulsation amplitudes of any such system known. The pulsation constant indicates that the mode is likely a first overtone radial pulsation.

  13. Time evolution of high-energy emissions of low-mass stars. I. Age determination using stellar chronology with white dwarfs in wide binaries

    NASA Astrophysics Data System (ADS)

    Garcés, A.; Catalán, S.; Ribas, I.

    2011-07-01

    Context. Stellar ages are extremely difficult to determine and often subject to large uncertainties, especially for field low-mass stars. We plan to carry out a calibration of the decrease in high-energy emissions of low-mass GKM stars with time, and therefore precise age determination is a key ingredient. The overall goal of our research is to study the time evolution of these high-energy emissions as an essential input to studying exoplanetary atmospheres. Aims: We propose to determine stellar ages with a methodology based on wide binaries. We are interested in systems composed of a low-mass star and a white dwarf (WD), where the latter serves as a stellar chronometer for the system. We aim at obtaining reliable ages for a sample of late-type stars older than 1 Gyr. Methods: We selected a sample of wide binaries composed by a DA type WD and a GKM companion. High signal-to-noise, low-resolution spectroscopic observations were obtained for most of the WD members of the sample. Atmospheric parameters were determined by fitting the spectroscopic data to appropiate WD models. The total ages of the systems were derived by using cooling sequences, an initial-final mass relationship and evolutionary tracks, to account for the progenitor life. Results: The spectroscopic observations have allowed us to determine ages for the binary systems using WDs as cosmochronometers. We obtained reliable ages for 27 stars between 1 and 5 Gyr, which is a range where age determination becomes difficult for field objects. Roughly half of these systems have cooling ages that contribute at least 30% the total age. We select those for further study since their age estimate should be less prone to systematic errors coming from the initial-final mass relationship. Conclusions: We have determined robust ages for a sizeable sample of GKM stars that can be subsequently used to study the time evolution of their emissions associated to stellar magnetic activity. Based on observations collected at

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

    SciTech Connect

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

    2012-07-10

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

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

    SciTech Connect

    Skinner, Stephen L.; Zhekov, Svetozar A.; Güdel, Manuel; Schmutz, Werner E-mail: szhekov@space.bas.bg E-mail: werner.schmutz@pmodwrc.ch

    2015-02-01

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

  16. A Chandra Observation of the Eclipsing Wolf-Rayet Binary CQ Cep

    NASA Astrophysics Data System (ADS)

    Skinner, Stephen L.; Zhekov, Svetozar A.; Güdel, Manuel; Schmutz, Werner

    2015-02-01

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

  17. δ Sct-type pulsations in eclipsing binary systems: RZ Cas

    NASA Astrophysics Data System (ADS)

    Rodríguez, E.; García, J. M.; Mkrtichian, D. E.; Costa, V.; Kim, S.-L.; López-González, M. J.; Hintz, E.; Kusakin, A. V.; Gamarova, A. Y.; Lee, J. W.; Youn, J.-H.; Janiashvili, E. B.; Garrido, R.; Moya, A.; Kang, Y. W.

    2004-02-01

    We present the results of a three-continent multisite photometric campaign carried out on the Algol-type eclipsing binary system RZ Cas, in which the primary component has recently been discovered to be a δ Sct-type pulsator. The present observations include, for the first time, complete simultaneous Strömgren uvby light curves together with a few Crawford Hβ data collected around the orbital phase of the first quadrature. The new observations confirm the pulsational behaviour of the primary component. A detailed photometric analysis, based on these observations, is presented for both binarity and pulsation. The results indicate a semidetached system where the secondary fills its Roche lobe. The appearance of the light curves reveals the presence of the mass stream from the secondary component and a hotspot where this stream impacts on the surface of the primary star. There are also some indications of chromospheric activity in the secondary. On the other hand, the pulsational behaviour out-of-primary eclipse can be well described with only one frequency at 64.1935 cd-1 similar to the main peak found by Ohshima et al. The existence of multiperiodicity is not confirmed in our data. Concerning the mode identification, our results indicate non-radial pulsation in a high radial order (n= 6), with l= 2, |m|= 1, 2 as the most suitable. However, additional effects must be taken into account in the predictions. Moreover, the pulsation amplitude in the u band is larger than in b and v, which is unusual among the δ Sct-type variables. This can be explained as due to pulsation in a high n value and close to the blue edge of the δ Sct region. On the other hand, the early data of Ohshima et al. have also been analysed and similar results are found concerning the frequency content and pulsational amplitude. Finally, a revision of all the photometric out-of-primary-eclipse data sets available in the literature is made together with some additional unpublished data leading to

  18. 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.

  19. TESTING THE CORE OVERSHOOT MIXING DESCRIBED BY A TURBULENT CONVECTION MODEL ON THE ECLIPSING BINARY STAR HY VIR

    SciTech Connect

    Zhang, Q. S.

    2012-12-20

    Helioseismic investigation has suggested applying turbulent convection models (TCMs) to convective overshoot. Using the turbulent velocity in the overshoot region determined by a TCM, one can deal with overshoot mixing as a diffusion process, which leads to incomplete mixing. It has been found that this treatment can improve solar sound speed and Li depletion in open clusters. In order to investigate whether the TCM can be applied to overshoot mixing outside the stellar convective core, new observations of the eclipsing binary star HY Vir are adopted to calibrate the overshoot mixing parameter. The main conclusions are as follows: (1) the solar TCM parameters and overshoot mixing parameter are also suitable for the eclipsing binary system HY Vir, (2) the incomplete mixing results in a continuous profile of hydrogen abundance, and (3) the e-folding length of the region, in which the hydrogen abundance changes due to overshoot mixing, increases during stellar evolution.

  20. A multiwavelength investigation of the massive eclipsing binary Cygnus OB2 #5

    NASA Astrophysics Data System (ADS)

    Linder, N.; Rauw, G.; Manfroid, J.; Damerdji, Y.; De Becker, M.; Eenens, P.; Royer, P.; Vreux, J.-M.

    2009-02-01

    Context: The properties of the early-type binary Cyg OB2 #5 have been debated for many years and spectroscopic and photometric investigations yielded conflicting results. Aims: We have attempted to constrain the physical properties of the binary by collecting new optical and X-ray observations. Methods: The optical light curves obtained with narrow-band continuum and line-bearing filters are analysed and compared. Optical spectra are used to map the location of the He ii λ 4686 and Hα line-emission regions in velocity space. New XMM-Newton as well as archive X-ray spectra are analysed to search for variability and constrain the properties of the hot plasma in this system. Results: We find that the orbital period of the system slowly changes though we are unable to discriminate between several possible explanations of this trend. The best fit solution of the continuum light curve reveals a contact configuration with the secondary star being significantly brighter and hotter on its leading side facing the primary. The mean temperature of the secondary star turns out to be only slightly lower than that of the primary, whilst the bolometric luminosity ratio is found to be 3.1. The solution of the light curve yields a distance of 925 ± 25 pc much lower than the usually assumed distance of the Cyg OB2 association. Whilst we confirm the existence of episodes of higher X-ray fluxes, the data reveal no phase-locked modulation with the 6.6 day period of the eclipsing binary nor any clear relation between the X-ray flux and the 6.7 yr radio cycle. Conclusions: The bright region of the secondary star is probably heated by energy transfer in a common envelope in this contact binary system as well as by the collision with the primary's wind. The existence of a common photosphere probably also explains the odd mass-luminosity relation of the stars in this system. Most of the X-ray, non-thermal radio, and possibly γ-ray emission of Cyg OB2 #5 is likely to arise from the

  1. Theoretical investigation of the neutron star in low-mass X-ray binary X1822-371 (V691 CrA)

    NASA Astrophysics Data System (ADS)

    Monowar Hossein, Sk.; Farhad, Nur; Molla, Sajahan; Kalam, Mehedi

    2016-06-01

    We propose a model for the neutron star in low-mass X-ray binary (LMXB) X1822-371 (V691 CrA) (Muñoz-Darius et al. in Astrophys. J. 635:502, 2005). Here we investigate the physical phenomena of the neutron star in LMXB X1822-371 (V691 CrA) by using the Tolman-IV solution (Tolman in Phys. Rev. 55:364, 1939). Using our model, we evaluate central density (ρ0), surface density (ρb), central pressure (p 0), surface redshift (Z s) and probable radius of the above mentioned neutron star, which is very much consistent with reported data. We also obtain a possible equation of state (EoS) of the star which is physically acceptable.

  2. A GENERAL RELATIVISTIC MAGNETOHYDRODYNAMIC MODEL OF HIGH FREQUENCY QUASI-PERIODIC OSCILLATIONS IN BLACK HOLE LOW-MASS X-RAY BINARIES

    SciTech Connect

    Shi Changsheng; Li Xiangdong E-mail: lixd@nju.edu.c

    2010-05-10

    We suggest a possible explanation for the high frequency quasi-periodic oscillations (QPOs) in black hole (BH) low-mass X-ray binaries. By solving the perturbation general relativistic magnetohydrodynamic equations, we find two stable modes of the Alfven wave in the accretion disks with toroidal magnetic fields. We suggest that these two modes may lead to the double high frequency QPOs if they are produced in the transition region between the inner advection-dominated accretion flow and the outer thin disk. This model naturally accounts for the 3:2 relation for the upper and lower frequencies of the QPOs, and the relation between the BH mass and QPO frequency.

  3. The First Low-mass Black Hole X-Ray Binary Identified in Quiescence Outside of a Globular Cluster

    NASA Astrophysics Data System (ADS)

    Tetarenko, B. E.; Bahramian, A.; Arnason, R. M.; Miller-Jones, J. C. A.; Repetto, S.; Heinke, C. O.; Maccarone, T. J.; Chomiuk, L.; Sivakoff, G. R.; Strader, J.; Kirsten, F.; Vlemmings, W.

    2016-07-01

    The observed relation between the X-ray and radio properties of low-luminosity accreting black holes (BHs) has enabled the identification of multiple candidate black hole X-ray binaries (BHXBs) in globular clusters (GCs). Here, we report an identification of the radio source VLA J213002.08+120904 (aka M15 S2), recently reported in Kirsten et al., as a BHXB candidate. They showed that the parallax of this flat-spectrum variable radio source indicates a {2.2}-0.3+0.5 kpc distance, which identifies it as lying in the foreground of the GC M15. We determine the radio characteristics of this source and place a deep limit on the X-ray luminosity of ∼4 × 1029 erg s‑1. Furthermore, we astrometrically identify a faint red stellar counterpart in archival Hubble images with colors consistent with a foreground star; at 2.2 kpc, its inferred mass is 0.1–0.2 M ⊙. We rule out that this object is a pulsar, neutron star X-ray binary, cataclysmic variable, or planetary nebula, concluding that VLA J213002.08+120904 is the first accreting BHXB candidate discovered in quiescence outside of a GC. Given the relatively small area over which parallax studies of radio sources have been performed, this discovery suggests a much larger population of quiescent BHXBs in our Galaxy, 2.6 × 104–1.7 × 108 BHXBs at 3σ confidence, than has been previously estimated (∼102–104) through population synthesis.

  4. An Initial Census of Eclipsing Binaries in the Pleiades and Hyades in Field 4 of the K2 Mission

    NASA Astrophysics Data System (ADS)

    Stauffer, John R.; Stassun, Keivan; Aigrain, Suzanne; Hillenbrand, Lynne; David, Trevor J.; Rebull, Luisa M.; K2 Young Clusters Team

    2016-01-01

    We have identified four new eclipsing binary members of the Pleiades and Hyades in the K2 Field 4 data.For one of those stars, where radial velocities are available, we report a complete SB1/EB orbital fit to the data.For the other EB candidates, we describe the information we have derived from the K2 light curve and what is known about the stars from the published literature.

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

    SciTech Connect

    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 with 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.

  6. 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).

  7. The EB Factory Project. I. A Fast, Neural-net-based, General Purpose Light Curve Classifier Optimized for Eclipsing Binaries

    NASA Astrophysics Data System (ADS)

    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 with 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.

  8. QUARK-NOVAE IN LOW-MASS X-RAY BINARIES. II. APPLICATION TO G87-7 AND TO GRB 110328A

    SciTech Connect

    Ouyed, Rachid; Staff, Jan; Jaikumar, Prashanth

    2011-12-20

    We propose a simple model explaining two outstanding astrophysical problems related to compact objects: (1) that of stars such as G87-7 (alias EG 50) that constitute a class of relatively low-mass white dwarfs (WDs) which nevertheless fall away from the C/O composition and (2) that of GRB 110328A/Swift J164449.3+57345 which showed spectacularly long-lived strong X-ray flaring, posing a challenge to standard gamma-ray burst models. We argue that both these observations may have an explanation within the unified framework of a quark-nova (QN) occurring in a low-mass X-ray binary (LMXB; neutron star (NS)-WD). For LMXBs, where the binary separation is sufficiently tight, ejecta from the exploding NS triggers nuclear burning in the WD on impact, possibly leading to Fe-rich composition compact WDs with mass 0.43 M{sub Sun} < M{sub WD} < 0.72 M{sub Sun }, reminiscent of G87-7. Our results rely on the assumption, which ultimately needs to be tested by hydrodynamic and nucleosynthesis simulations, that under certain circumstances the WD can avoid the thermonuclear runaway. For heavier WDs (i.e., M{sub WD} > 0.72 M{sub Sun }) experiencing the QN shock, degeneracy will not be lifted when carbon burning begins, and a sub-Chandrasekhar Type Ia supernova may result in our model. Under slightly different conditions and for pure He WDs (i.e., M{sub WD} < 0.43 M{sub Sun }), the WD is ablated and its ashes raining down on the quark star (QS) leads to accretion-driven X-ray luminosity with energetics and duration reminiscent of GRB 110328A. We predict additional flaring activity toward the end of the accretion phase if the QS turns into a black hole.

  9. The X-Ray Luminosity Functions of Field Low-Mass X-Ray Binaries in Early-Type Galaxies: Evidence for a Stellar Age Dependence

    NASA Technical Reports Server (NTRS)

    Lehmer, B. D.; Berkeley, M.; Zezas, A.; Alexander, D. M.; Basu-Zych, A.; Bauer, F. E.; Brandt, W. N.; Fragos, T.; Hornschemeier, A. E.; Kalogera, V.; Ptak, A.; Sivakoff, G. R.; Tzanavaris, P.; Yukita, M.

    2014-01-01

    We present direct constraints on how the formation of low-mass X-ray binary (LMXB) populations in galactic fields depends on stellar age. In this pilot study, we utilize Chandra and Hubble Space Telescope (HST) data to detect and characterize the X-ray point source populations of three nearby early-type galaxies: NGC 3115, 3379, and 3384. The luminosity-weighted stellar ages of our sample span approximately equal to 3-10 Gyr. X-ray binary population synthesis models predict that the field LMXBs associated with younger stellar populations should be more numerous and luminous per unit stellar mass than older populations due to the evolution of LMXB donor star masses. Crucially, the combination of deep Chandra and HST observations allows us to test directly this prediction by identifying and removing counterparts to X-ray point sources that are unrelated to the field LMXB populations, including LMXBs that are formed dynamically in globular clusters, Galactic stars, and background AGN/galaxies. We find that the "young" early-type galaxy NGC 3384 (approximately equals 2-5 Gyr) has an excess of luminous field LMXBs (L(sub x) approximately greater than (5-10) × 10(exp 37) erg s(exp -1)) per unit K-band luminosity (L(sub K); a proxy for stellar mass) than the "old" early-type galaxies NGC 3115 and 3379 (approximately equals 8-10 Gyr), which results in a factor of 2-3 excess of L(sub X)/L(sub K) for NGC 3384. This result is consistent with the X-ray binary population synthesis model predictions; however, our small galaxy sample size does not allow us to draw definitive conclusions on the evolution field LMXBs in general. We discuss how future surveys of larger galaxy samples that combine deep Chandra and HST data could provide a powerful new benchmark for calibrating X-ray binary population synthesis models.

  10. The X-ray luminosity functions of field low-mass X-ray binaries in early-type galaxies: Evidence for a stellar age dependence

    SciTech Connect

    Lehmer, B. D.; Tzanavaris, P.; Yukita, M.; Berkeley, M.; Basu-Zych, A.; Hornschemeier, A. E.; Ptak, A.; Zezas, A.; Alexander, D. M.; Bauer, F. E.; Brandt, W. N.; Fragos, T.; Kalogera, V.; Sivakoff, G. R.

    2014-07-01

    We present direct constraints on how the formation of low-mass X-ray binary (LMXB) populations in galactic fields depends on stellar age. In this pilot study, we utilize Chandra and Hubble Space Telescope (HST) data to detect and characterize the X-ray point source populations of three nearby early-type galaxies: NGC 3115, 3379, and 3384. The luminosity-weighted stellar ages of our sample span ≈3-10 Gyr. X-ray binary population synthesis models predict that the field LMXBs associated with younger stellar populations should be more numerous and luminous per unit stellar mass than older populations due to the evolution of LMXB donor star masses. Crucially, the combination of deep Chandra and HST observations allows us to test directly this prediction by identifying and removing counterparts to X-ray point sources that are unrelated to the field LMXB populations, including LMXBs that are formed dynamically in globular clusters, Galactic stars, and background active galactic nuclei/galaxies. We find that the 'young' early-type galaxy NGC 3384 (≈2-5 Gyr) has an excess of luminous field LMXBs (L {sub X} ≳ (5-10) × 10{sup 37} erg s{sup –1}) per unit K-band luminosity (L{sub K} ; a proxy for stellar mass) than the 'old' early-type galaxies NGC 3115 and 3379 (≈8-10 Gyr), which results in a factor of ≈2-3 excess of L {sub X}/L{sub K} for NGC 3384. This result is consistent with the X-ray binary population synthesis model predictions; however, our small galaxy sample size does not allow us to draw definitive conclusions on the evolution field LMXBs in general. We discuss how future surveys of larger galaxy samples that combine deep Chandra and HST data could provide a powerful new benchmark for calibrating X-ray binary population synthesis models.

  11. BVRI Photometric Study of the Totally Eclipsing Short Period Solar Type, Near-Contact W UMA Binary, NSVS 5066754

    NASA Astrophysics Data System (ADS)

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

    2016-06-01

    High precision BVRcIc light curves of NSVS 5066754 were observed on May 17-20, 2014 at Dark Sky Observatory in North Carolina with the 0.81-m reflector of Appalachian State University. It is a solar type eclipsing binary (T1~5750 K) with a period of only 0.375132 (1) d. In fact, it appeared as one of the shortest period in Shaw’s list of near contact binaries. Therefore, we initially believed this to be a pre-contact WUMa Binary (PCWB’s). However, the Binary Maker fits and our Wilson-Devinney solutions show that the binary could have either a semi-detached or a contact binary configuration.Five times of minimum light were calculated, for 3 primary and 2 secondary eclipses from our present observations: In addition, observations at minima were introduced from archived All Sky Automated Survey Data along with the discovery ephemeris. The following decreasing quadratic ephemeris was determined from all available times of minimum light:JDHelMinI=2456797.63848±0.00047d + 0.3747796± 0. 0000068 X E --0.0000000241± 0.0000000005X E2Our contact solution, with a sum of square residuals = 0.49, gave a mass ratio of 0.50, and a component temperature difference of ~360 K, somewhat large for a contact binary. Two substantial cool spots were determined in this solution of 37 deg and 28 deg radius with a t-factor or 0.92 and 0.78 respectively. The fill-out is very shallow, ~6%.The semi-detached solution (mode 4: V1010 Oph configuration, meaning the system is approaching first contact) is of poorer quality with a sum of square residuals = 0.87. It has a mass ratio of 0.63, and a component temperature of ~460 K. The fill-outs are 100% and 97% for the primary and secondary components, respectively. Two spots were determined, one hot (t-factor of 1.16, 14 deg radius, colatitude 101 deg) and one cool spot (t-factor of 0.94, 48 deg radius, colatitude 90 deg). The models in both cases are total eclipsing with high inclinations in the 86-89 deg range, and a time of constant light is

  12. Fundamental stellar and accretion disc parameters of the eclipsing binary DQ Velorum

    NASA Astrophysics Data System (ADS)

    Barría, D.; Mennickent, R. E.; Schmidtobreick, L.; Djurašević, G.; Kołaczkowski, Z.; Michalska, G.; Vučković, M.; Niemczura, E.

    2013-04-01

    Context. To add to the growing collection of well-studied double periodic variables (DPVs) we have carried out the first spectroscopic and photometric analysis of the eclipsing binary DQ Velorum to obtain its main physical stellar and orbital parameters. Aims: Combining spectroscopic and photometric observations that cover several orbital cycles allows us to estimate the stellar properties of the binary components and the orbital parameters. We also searched for circumstellar material around the more massive star. Methods: We separated DQ Velorum composite spectra and measured radial velocities with an iterative method for double spectroscopic binaries. We obtained the radial velocity curves and calculated the spectroscopic mass ratio. We compared our single-lined spectra with a grid of synthetic spectra and estimated the temperature of the stars. We modeled the V-band light curve with a fitting method based on the simplex algorithm, which includes an accretion disc. To constrain the main stellar parameters we fixed the mass ratio and donor temperature to the values obtained by our spectroscopic analysis. Results: We obtain a spectroscopic mass ratio q = 0.31 ± 0.03 together with donor and gainer masses Md = 2.2 ± 0.2 M⊙, Mg = 7.3 ± 0.3 M⊙, the radii Rd = 8.4 ± 0.2 R⊙, Rg = 3.6 ± 0.2 R⊙ and temperatures Td = 9400 ± 100 K, Tg = 18 500 ± 500 K for the stellar components. We find that DQ Vel is a semi-detached system consisting of a B3V gainer and an A1III donor star plus an extended accretion disc around the gainer. The disc is filling 89% of the gainer Roche lobe with a temperature of 6580 ± 300 K at the outer radius. It has a concave shape that is thicker at its edge (de = 0.6 ± 0.1 R⊙) than at its centre (dc = 0.3 ± 0.1 R⊙). We find a significant sub-orbital frequency of 0.19 d-1 in the residuals of the V-band light curve, which we interpret as a pulsation of an slowly pulsating B-type (SPB) of a gainer star. We also estimate the distance to

  13. BINARIES DISCOVERED BY THE MUCHFUSS PROJECT: SDSS J08205+0008-AN ECLIPSING SUBDWARF B BINARY WITH A BROWN DWARF COMPANION

    SciTech Connect

    Geier, S.; Schaffenroth, V.; Drechsel, H.; Heber, U.; Kupfer, T.; Tillich, A.; Oestensen, R. H.; Smolders, K.; Degroote, P.; Maxted, P. F. L.; Barlow, B. N.; Gaensicke, B. T.; Marsh, T. R.; Napiwotzki, R.

    2011-04-20

    Hot subdwarf B stars (sdBs) are extreme horizontal branch stars believed to originate from close binary evolution. Indeed about half of the known sdB stars are found in close binaries with periods ranging from a few hours to a few days. The enormous mass loss required to remove the hydrogen envelope of the red-giant progenitor almost entirely can be explained by common envelope ejection. A rare subclass of these binaries are the eclipsing HW Vir binaries where the sdB is orbited by a dwarf M star. Here, we report the discovery of an HW Vir system in the course of the MUCHFUSS project. A most likely substellar object ({approx_equal}0.068 M{sub sun}) was found to orbit the hot subdwarf J08205+0008 with a period of 0.096 days. Since the eclipses are total, the system parameters are very well constrained. J08205+0008 has the lowest unambiguously measured companion mass yet found in a subdwarf B binary. This implies that the most likely substellar companion has not only survived the engulfment by the red-giant envelope, but also triggered its ejection and enabled the sdB star to form. The system provides evidence that brown dwarfs may indeed be able to significantly affect late stellar evolution.

  14. CHARACTERIZING THE COOL KOIs. V. KOI-256: A MUTUALLY ECLIPSING POST-COMMON ENVELOPE BINARY

    SciTech Connect

    Muirhead, Philip S.; Shporer, Avi; Becker, Juliette; Swift, Jonathan J.; Hinkley, Sasha; Pineda, J. Sebastian; Bottom, Michael; Baranec, Christoph; Riddle, Reed; Tendulkar, Shriharsh P.; Bui, Khanh; Vanderburg, Andrew; Lloyd, James P.; Fuller, Jim; Zhao, Ming; Howard, Andrew W.; Von Braun, Kaspar; Boyajian, Tabetha S.; Law, Nicholas; Ramaprakash, A. N.; and others

    2013-04-20

    We report that Kepler Object of Interest 256 (KOI-256) is a mutually eclipsing post-common envelope binary (ePCEB), consisting of a cool white dwarf (M{sub *} = 0.592 {+-} 0.089 M{sub Sun }, R{sub *} = 0.01345 {+-} 0.00091 R{sub Sun }, T{sub eff} = 7100 {+-} 700 K) and an active M3 dwarf (M{sub *} = 0.51 {+-} 0.16 M{sub Sun }, R{sub *} = 0.540 {+-} 0.014 R{sub Sun }, T{sub eff} = 3450 {+-} 50 K) with an orbital period of 1.37865 {+-} 0.00001 days. KOI-256 is listed as hosting a transiting planet-candidate by Borucki et al. and Batalha et al.; here we report that the planet-candidate transit signal is in fact the occultation of a white dwarf as it passes behind the M dwarf. We combine publicly-available long- and short-cadence Kepler light curves with ground-based measurements to robustly determine the system parameters. The occultation events are readily apparent in the Kepler light curve, as is spin-orbit synchronization of the M dwarf, and we detect the transit of the white dwarf in front of the M dwarf halfway between the occultation events. The size of the white dwarf with respect to the Einstein ring during transit (R{sub Ein} = 0.00473 {+-} 0.00055 R{sub Sun }) causes the transit depth to be shallower than expected from pure geometry due to gravitational lensing. KOI-256 is an old, long-period ePCEB and serves as a benchmark object for studying the evolution of binary star systems as well as white dwarfs themselves, thanks largely to the availability of near-continuous, ultra-precise Kepler photometry.