Binary BD Research Articles

BD+47 378: An Eclipsing Binary Containing a δ Sct Pulsating Star

New high-resolution spectra of the eclipsing binary BD+47 378 were obtained on five nights between 2020 and 2021 with the Bohyunsan Observatory Echelle Spectrograph in Korea. We collected the TESS light curve of the system obtained from Sectors 17 to 18, which shows a flat bottom at the secondary eclipse, an O’Connell effect, and oscillation features. From the spectral analysis, the radial velocities (RVs) of the primary and secondary stars were obtained, and the temperature of the brighter and more massive primary component was determined to be 7140 ± 100 K. According to a simultaneous analysis of the double-lined RVs and TESS light curves, the masses and radii of both components are M 1 = 1.69 ± 0.03 M ⊙, M 2 = 0.80 ± 0.02 M ⊙, R 1 = 2.01 ± 0.01 R ⊙, and R 2 = 0.79 ± 0.01 R ⊙, respectively. The primary component of the system is located on the δ Sct and γ Dor instability strips. After subtracting the theoretical light curve from the TESS data, a total of four independent frequencies (5.7235 day−1, 6.2577 day−1, 6.9588 day−1, and 14.7675 day−1) were detected using the multiple frequency analysis. These frequencies are typical of a δ Sct pulsator. The results reveal that BD+47 378 is a detached system consisting of two main-sequence stars with a δ Sct type primary component.

Spectroscopic and photometric analysis of symbiotic candidates – I. Ten candidates on classical symbiotic stars

ABSTRACT Symbiotic stars belong to a group of interacting binaries that display a wide variety of phenomena, including prominent outbursts connected with mass transfer, as well as stellar winds, jets, eclipses, or intrinsic variability of the components. Dozens of new symbiotic stars and candidates have been discovered in recent years. However, there are many objects that are still poorly studied. Some symbiotic candidates suspected in the literature have never been studied spectroscopically. In this contribution, we present the first results of the ongoing campaign focused on symbiotic candidates. In the first paper in the series, we study the nature of 10 candidate classical symbiotic stars suspected based on their photometric behaviour, colours or abundance pattern. To confirm or reject the symbiotic nature of the studied candidates, we obtained new spectra and analysed them in detail together with available multifrequency photometric and spectroscopic observations of the objects. Hen 3−860 and V2204 Oph are genuine symbiotic systems showing typical spectral features of burning symbiotic stars and outbursts in the last 100 yr. The first object belongs to the uncommon group of eclipsing symbiotic stars. V1988 Sgr cannot be classified as a genuine burning symbiotic star, but the scenario of an accreting-only symbiotic system cannot be ruled out. Hen 4−204 might be a bonafide symbiotic star due to its similarity with the known symbiotic binary BD Cam. Six other symbiotic candidates (V562 Lyr, IRAS 19050+0001, EC 19249−7343, V1017 Cyg, PN K1−6, V379 Peg) are either single dwarf or giant stars or non-symbiotic binaries.

V680 Mon – a young mercury–manganese star in an eclipsing heartbeat system

ABSTRACT Chemically peculiar stars in eclipsing binary systems are rare objects that allow the derivation of fundamental stellar parameters and important information on evolutionary status and the origin of the observed chemical peculiarities. Here we present an investigation of the known eclipsing binary system BD+09 1467 = V680 Mon. Using spectra from the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) and own observations, we identify the primary component of the system as a mercury–manganese (HgMn/CP3) star (spectral type kB9 hB8 HeB9 V HgMn). Furthermore, photometric time series data from the Transiting Exoplanet Survey Satellite (TESS) indicate that the system is a ‘heartbeat star’, a rare class of eccentric binary stars with short-period orbits that exhibit a characteristic signature near the time of periastron in their light curves due to the tidal distortion of the components. Using all available photometric observations, we present an updated ephemeris and binary system parameters as derived from a modelling of the system with the elisa code, which indicate that the secondary star has an effective temperature of Teff = $8300_{-200}^{+200}$ (spectral type ∼A4). V680 Mon is only the fifth known eclipsing CP3 star, and the first one in a heartbeat binary. Furthermore, our results indicate that the star is located on the zero-age main sequence and a possible member of the open cluster NGC 2264. As such, it lends itself perfectly for detailed studies and may turn out to be a keystone in the understanding of the development of CP3 star peculiarities.

Close eclipsing binary BD And: a triple system

BD And is a fairly bright (V = 10.8), active and close (P = 0.9258 days) eclipsing binary. The cyclic variability of the apparent orbital period as well as third light in the light curves indicate the presence of an additional late-type component. The principal aim is the spectroscopic testing of the third-body hypothesis and determination of absolute stellar parameters for both components of the eclipsing binary. First medium and high-resolution spectroscopy of the system was obtained. The broadening-function technique appropriate for heavily-broadened spectra of close binaries was used. The radial velocities were determined fitting the Gaussian functions and rotational profiles to the broadening functions. A limited amount of photometric data has also been obtained. Although the photometric observations were focused on the obtaining the timing information, a cursory light-curve analysis was also performed. Extracted broadening functions clearly show the presence of a third, slowly-rotating component. Its radial velocity is within error of the systemic velocity of the eclipsing pair, strongly supporting the physical bond. The observed systemic radial-velocity and third-component changes do not support the 9 year orbit found from the timing variability. Masses of the components of the eclipsing pair are determined with about 0.5% precision. Further characterization of the system would require long-term photometric and spectroscopic monitoring.

System Parameters for the Eclipsing B-star Binary BD+11°3569

Abstract We present the results from a combined spectroscopic and photometric in-depth study of the binary system BD+11o3569 (B4 V + B5 V). Fits to Johnson V, Cousins R C and I C photometry, and radial velocities yield an orbital period of 1.49712598 ± 0.00000020 days and an inclination of 82.°93 ± 0.°17. The combined light curves and radial velocity solution give masses and radii of M 1 = 5.259 ± 0.064 M ⊙ with M 2 = 4.325 ± 0.040 M ⊙ and R 1 = 3.509 ± 0.018 R ⊙ with R 2 = 2.570 ± 0.023 R ⊙. We find that the system does not match a single age isochrone when derived astrophysical quantities for the components are compared with theoretical stellar models, but are bounded by 32 and 40 Myr isochrones. We estimate a distance to the system of 1130 ± 150 pc, which agrees reasonably with the published Gaia distance.

The orbital elements and physical properties of the eclipsing binary BD+36°3317, a probable member ofδLyrae cluster

Context. The fact that eclipsing binaries belong to a stellar group is useful, because the former can be used to estimate distance and additional properties of the latter, and vice versa. Aims. Our goal is to analyse new spectroscopic observations of BD$+36^\circ3317$ along with the photometric observations from the literature and, for the first time, to derive all basic physical properties of this binary. We aim to find out whether the binary is indeed a member of the $\delta$ Lyr open cluster. Methods. The spectra were reduced using the IRAF program and the radial velocities were measured with the program SPEFO. The line spectra of both components were disentangled with the program KOREL and compared to a grid of synthetic spectra. The final combined radial-velocity and photometric solution was obtained with the program PHOEBE. Results. We obtained the following physical elements of BD$+36^\circ3317$: $M_1 = 2.24\pm0.07 M_{\odot}$, $M_2 = 1.52\pm0.03 M_{\odot}$, $R_1 = 1.76\pm0.01 R_{\odot}$, $R_2 = 1.46\pm0.01 R_{\odot}$, $log L_1 = 1.52\pm0.08 L_{\odot}$, $log L_2 = 0.81\pm0.07 L_{\odot}$. We derived the effective temperatures $T_{eff,1} = 10450 \pm 420$ K, $T_{eff,2} = 7623 \pm 328$ K. Both components are located close to ZAMS in the Hertzsprung-Russell (HR) diagram and their masses and radii are consistent with the predictions of stellar evolutionary models. Our results imply the average distance to the system d = $330\pm29$ pc. We re-investigated the membership of BD$+36^\circ3317$ in the $\delta$ Lyr cluster and confirmed it. The distance to BD$+36^\circ3317$, given above, therefore represents an accurate estimate of the true distance for $\delta$ Lyr cluster. Conclusions. The reality of the $\delta$ Lyr cluster and the cluster membership of BD$+36^\circ3317$ have been reinforced.

Orbit and properties of the massive X-ray binary BD +60 73=IGR J00370+6122

Context. High-energy X-rays generated in massive binary systems can arise from several different mechanisms. Constraints on the orbital parameters of these systems are therefore necessary to properly understand and interpret the X-ray phenomena. Aims. In this study we aim to determine a spectroscopic orbit for the high-mass X-ray binary system BD +60 73=IGR J00370+6122, to infer the properties of the optical and compact companion, and to interpret the characteristics of the X-ray light curve within the context of our findings. Methods. We acquired 123 spectroscopic observations with the David Dunlap Observatory and Kitt Peak National Observatory telescopes in the optical domain. Using a cross-correlation technique, we measured the radial velocity of each of these spectra relative to the heliocentric rest-frame. An orbital solution was obtained from the resulting radial velocity measurements. Spectra of several spectral standards were also acquired to reassess the spectral classification of the optical companion. Results. The best-fit orbital parameters suggest an eccentricity of e = 0.48 +0.02 −0.03 and a mass-function of f(M) = 0.009 ±0.002, lending further support to the assumption that the companion is a low-mass compact star. We find that the X-ray maximum occurs just after the time of periastron passage, but before the time of superior conjunction when the optical companion could eclipse the compact companion. The spectrum of the optical companion is best matched by the B1Ib spectral standard HD24398, which reaffirms the original classification. Conclusions. The mass-function combined with a plausible range of possible masses for a neutron star companion yields primary masses within the range expected for the spectral type of BD +60 73 for high orbital inclinations. The compact companion cannot be a black hole unless the supergiant has an exceptionally high mass for its B1Ib spectral type or if the inclination of its orbit is very low. The X-ray timing and characteristics can potentially be explained by accretion variations on the compact object; but this would require the companion to be a magnetar.

A γ Doradus candidate in eclipsing binary BD And?

The BVR photometric light curves of the eclipsing binary BD And were obtained in 2008 and 2009. We estimated the mass ratio of the system as 0.97 and the photometric solutions were derived. The results show that BD And is a detached binary system, whose components have a little temperature difference of about 40K. By analyzing photometric available light minimum times, we also derived an update ephemeris and found for the first time a possible periodic oscillation with an amplitude of 0.011days and a period of 9.6years. The results indicate that the periodic oscillation could be caused by a third component physically attached to the eclipsing binary. After removing the light variations due to the eclipses and proximity effects, the light-curve distortions are further explained by the pulsation of the primary component with a dominant period of ∼1day. In accordance with the position of the primary component on the Hertzsprung–Russell diagram and its pulsation period, the primary component of BD And could be an excellent γ Doradus candidate. It is rarely phenomenon that a component of the eclipsing binary system is a γ Doradus variable.

WASP-77 Ab: A Transiting Hot Jupiter Planet in a Wide Binary System11Based on observations made with ESO Telescopes at the La Silla Paranal Observatory under programme ID 088.C-0011.

ABSTRACTWe report the discovery of a transiting planet with an orbital period of 1.36 days orbiting the brighter component of the visual binary star BD -07 436. The host star, WASP-77 A, is a moderately bright G8 V star (V = 10.3) with a metallicity close to solar ([Fe/H] = 0.0 ± 0.1). The companion star, WASP-77 B, is a K-dwarf approximately 2 mag fainter at a separation of approximately 3″. The spectrum of WASP-77 A shows emission in the cores of the Caii H and K lines, indicative of moderate chromospheric activity. The Wide Angle Search for Planets (WASP) light curves show photometric variability with a period of 15.3 days and an amplitude of about 0.3% that is probably due to the magnetic activity of the host star. We use an analysis of the combined photometric and spectroscopic data to derive the mass and radius of the planet (1.76 ± 0.06 MJup, 1.21 ± 0.02 RJup). The age of WASP-77 A estimated from its rotation rate (∼1 Gyr) agrees with the age estimated in a similar way for WASP-77 B (∼0.6 Gyr) but is in poor agreement with the age inferred by comparing its effective temperature and density to stellar models (∼8 Gyr). Follow-up observations of WASP-77 Ab will make a useful contribution to our understanding of the influence of binarity and host star activity on the properties of hot Jupiters.

Polarimetric coronagraphy of BD + 31°643

Context. The binary B5V star BD+31?643 exhibits a disk-like structure detected at optical wavelengths. Even though the feature is well centered on the star, it has been argued, based on Spitzer observations, that the feature is a filament not directly associated to the binary star. Aims. The purpose of the present paper is to investigate whether polarization imaging may provide evidence either for or against the disk hypothesis. In addition, we aim at clarifying whether there might be any additional close companion to the binary star. Methods. We used the coronagraph PolCor in its polarization mode in combination with an EMCCD camera allowing short unit exposure times. As a result of shift-and-add and frame selection, the spatial resolution is improved compared to traditional CCD imaging. In order to possibly reveal an additional stellar companion, we used high resolution spectroscopy in the optical and high spatial resolution imaging in the near-IR. Results. The disk/filament is much better seen in polarization; it is narrow and a line drawn along the ridge passes within a second of arc from the star. The degree of polarization is high (?50% after correction for the extended component of the reflection nebula) which means that the disk/filament must be approximately at the same distance as the star. Although we confirm that the feature is much brighter south-east than north-west of the star, the evidence that the feature is physically connected to the star is strengthened and suggests that we are witnessing the destruction process of an accretion disk. Our spectroscopy shows that at least one of the stars is a spectroscopic binary. We were, however, not able to spatially resolve any stellar component in addition to the two well separated stars.

THIRD COMPONENT SEARCH AND ABUNDANCES OF THE VERY DUSTY SHORT-PERIOD BINARY BD +20°307

We have obtained near-infrared adaptive optics imaging and collected additional radial velocity observations to search for a third component in the extremely dusty short-period binary system BD +20 Degree-Sign 307. Our image shows no evidence for a third component at separations greater than 19 AU. Our four seasons of radial velocities have a constant center-of-mass velocity and are consistent with the systemic velocities determined at two earlier epochs. Thus, the radial velocities also provide no support for a third component. Unfortunately, the separation domains covered by our imaging and radial velocity results do not overlap. Thus, we examined the parameters for possible orbits of a third component that could have been missed by our current observations. With our velocities we determined improved circular orbital elements for the 3.4 day double-lined binary. We also performed a spectroscopic abundance analysis of the short-period binary components and conclude that the stars are a mid- and a late-F dwarf. We find that the iron abundances of both components, [Fe/H] = 0.15, are somewhat greater than the solar value and comparable to that of stars in the Hyades. Despite the similarity of the binary components, the lithium abundances of the two stars are very unequal.more » The primary has log {epsilon} (Li) = 2.72, while in the secondary log {epsilon} (Li) {<=}1.46, which corresponds to a difference of at least a factor of 18. The very disparate lithium abundances in very similar stars make it impossible to ascribe a single age to them. While the system is likely at least 1 Gyr old, it may well be as old as the Sun.« less

BD+36 3317: An algol type eclipsing binary in Delta Lyrae cluster

In this paper, we present standard Johnson UBV photometry of the eclipsing binary BD+36 3317 which is known as a member of Delta Lyrae (Stephenson 1) cluster. We determined colors and brightness of the system, calculated E(B−V) color excess. We discovered that the system shows total eclipse in secondary minimum. Using this advantage, we found that the primary component of the system has B9−A0 spectral type. Although there is no published orbital solution, we tried to estimate the physical properties of the system from simultaneous analysis of UBV light curves with 2003 version of Wilson–Devinney code. Then we considered photometric solution results together with evolutionary models and estimated the masses of the components as M1=2.5M⊙ and M2=1.6M⊙. Those estimations gave the distance of the system as 353pc. Considering the uncertainties in distance estimation, resulting distance is in agreement with the distance of Delta Lyrae cluster.

Magnetic properties of three cool CP stars with strong fields

AbstractThe study of magnetic fields of cool chemically peculiar stars with effective temperatures less than 10 000 K is very important to understand the nature of their magnetism. We present new results of a long‐term spectroscopic monitoring of the well‐known magnetic star HD 178892. The analysis of spectra taken with the Russian 6‐m telescope has revealed a periodic variation of the surface magnetic field from 17 to 23 kG. A revised rotational period of HD 178892 was extracted from the mean longitudinal field: 8.2549 days. We have continued the study of the components of the magnetic binary BD +40°175 started by V. Elkin at SAO RAS. Our measurements of magnetically splitted lines in the spectra of each component show the presence of strong magnetic fields in both components. The surface field in the case of the component A was about 14 kG at three different epochs. The component B possesses a slightly weaker field: Bs varies from 9 to 11 kG. A preliminary analysis of the chemical abundances allows us to make an assumption about the roAp nature of both components of BD +40°175 (© 2011 WILEY‐VCH Verlag GmbH &amp; Co. KGaA, Weinheim)

Physical parameters and orbit of the eclipsing binary BD +66 1663 = GSC 4479 412

We have obtained the first UBV(RI)C photoelectric light curves of the recently discovered eclipsing binary BD +66 1663 = GSC 4479 412 (P = 7.04d, V = 10.14). We have derived relative and absolute parameters of the binary, and analyzed the interstellar extinction towards the object. Though the star is located in the field of the young open cluster Be 59, we demonstrate that it is not a member.

Planetary Systems around Close Binary Stars: The Case of the Very Dusty, Sun‐like, Spectroscopic Binary BD+20 307

Field star BD+20 307 is the dustiest known main-sequence star, based on the fraction of its bolometric luminosity, 4%, that is emitted at infrared wavelengths. The particles that carry this large infrared luminosity are unusually warm, comparable to the temperature of the zodiacal dust in the solar system, and their existence is likely to be a consequence of a fairly recent collision of large objects such as planets or planetary embryos. Thus, the age of BD+20 307 is potentially of interest in constraining the era of terrestrial planet formation. The present project was initiated with an attempt to derive this age using the Chandra X-Ray Observatory to measure the X-ray flux of BD+20 307 in conjunction with extensive photometric and spectroscopic monitoring observations from Fairborn Observatory. However, the recent realization that BD+20 307 is a short-period, double-line, spectroscopic binary whose components have very different lithium abundances vitiates standard methods of age determination. We find the system to be metal-poor; this, combined with its measured lithium abundances, indicates that BD+20 307 may be several to many Gyr old. BD+20 307 affords astronomy a rare peek into a mature planetary system in orbit around a close binary star (because such systems are not amenable to study by the precision radial velocity technique).

BD −22 5866: A Low‐Mass, Quadruple‐lined SpectroscopicandEclipsing Binary

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 -->dAB 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.

Light-Curve and Radial Velocity Study of the Contact Binary BD +42 2782

BD +42 2782 was recently discovered to be a variable star with a W UMa-type, eclipsing-binary light curve. We have obtained the first photoelectric light curves (RC, IC) and also the first radial velocity curves for this binary. These show the system to be a W UMa binary of the W type, with the less massive component eclipsed at primary minimum. The light and velocity curves have been analyzed in a consistent manner using the Wilson-Devinney synthetic light-curve code. The binary has an orbital inclination of 74°, a mass ratio of 0.48, a secondary component ~150 K hotter than the primary, and an overcontact fill-out factor of 34%. Absolute parameters of the component stars are M1 = 1.38 M⊙, R1 = 1.29 R⊙, L1 = 1.75 L⊙, and M2 = 0.67 M⊙, R2 = 0.95 R⊙, L2 = 1.05 L⊙, and the calculated distance is 124 ± 15 pc. Even when corrected for energy transfer between the two components, the more massive component is found to be underluminous for its mass. Several means to explain this are explored, but no completely satisfactory explanation is found.

A search for wide visual companions of exoplanet host stars: The Calar Alto Survey

We have carried out a search for co-moving stellar and substellar companions around 18 exoplanet host stars with the infrared camera MAGIC at the 2.2 m Calar Alto telescope, by comparing our images with images from the all sky surveys 2MASS, POSS I and II. Four stars of the sample namely HD80606, 55 Cnc, HD46375 and BD–10°3166, are listed as binaries in the Washington Visual Double Star Catalogue (WDS). The binary nature of HD80606, 55 Cnc, and HD46375 is confirmed with both astrometry as well as photometry, thereby the proper motion of the companion of HD46375 was determined here for the first time.We derived the companion masses as well as the longterm stability regions for additional companions in these three binary systems. We can rule out further stellar companions around all stars in the sample with projected separations between 270AU and 2500AU, being sensitive to substellar companions with masses down to ∼60 MJup (S /N = 3). Furthermore we present evidence that the two components of the WDS binary BD–10°3166 are unrelated stars, i.e this system is a visual pair. The spectrophotometric distance of the primary (a K0 dwarf) is ∼67 pc, whereas the presumable secondary BD–10°3166B (a M4 to M5 dwarf) is located at a distance of 13 pc in the foreground. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Ubv(Ri)C Photometry of the Contact W Uma Binary Bd + 14∘5016

Ubv(Ri)C Photometry of the Contact W Uma Binary Bd + 14∘5016

Optical Photometry and X-Ray Monitoring of the "Cool Algol" BD +05706: Determination of the Physical Properties

We present new photometric observations in the BVRI bands of the double-lined eclipsing binary BD +05°706 conducted over three observing seasons, as well as new X-ray observations obtained with ROSAT covering a full orbital cycle (P = 18.9 days). A detailed light-curve analysis of the optical data shows the system to be semidetached, confirming indications from an earlier analysis by Torres et al. (published in 1998), with the less massive and cooler star filling its Roche lobe. The system is a member of the rare class of cool Algol systems, which are different from the classical Algol systems in that the mass-gaining component is also a late-type star rather than a B- or A-type star. By combining the new photometry with a reanalysis of the spectroscopic observations reported by Torres et al., we derive accurate absolute masses for the components of M1 = 2.633 ± 0.028 M⊙ and M2 = 0.5412 ± 0.0093 M⊙, radii of R1 = 7.55 ± 0.20 R⊙ and R2 = 11.02 ± 0.21 R⊙, as well as effective temperatures of 5000 ± 100 and 4640 ± 150 K, for the primary and secondary, respectively. There are obvious signs of activity (spottedness) in the optical light curve of the binary. Our X-ray light curve clearly shows the primary eclipse but not the secondary eclipse, suggesting that the primary star is the dominant source of the activity in the system. The depth and duration of the eclipse allow us to infer some of the properties of the X-ray–emitting region around that star.