scholarly journals Synchronous Rotation in the Eclipsing Binary 68 Herculis Inferred from Doppler Shifts in its Spectrum and Light Curve Modeling

2014 ◽  
Vol 121 (1-4) ◽  
pp. 5-15 ◽  
Author(s):  
Kenneth W. McLaughlin ◽  
Janak Panthi
Keyword(s):  
Radial Velocity ◽  
Binary Systems ◽  
Primary Component ◽  
Stellar Rotation ◽  
Eclipsing Binary ◽  
Doppler Shifts ◽  
Synchronous Rotation ◽  
Orbital Revolution ◽  
Curve Modeling ◽  
Contact Binary

Our differential photometry of the eclipsing binary 68 Herculis through V- and R-filters shows periodic minima consistent with a previously established period. As a function of its orbital motion, we report spectra over a limited wavelength range encompassing H-alpha 656.3 nm and helium 667.8 nm lines. Doppler shifts of both stars were resolved in H-alpha, while only the more massive star rendered the helium line with Doppler shifts that agree with the radial velocity we derive for it from the H-alpha profile. Sinusoidal curve-fits to the orbital dependence of the radial velocities imply circular orbits for both components, with amplitudes indicating a mass ratio for the two stars in agreement with published values. A subtle Doppler shift associated with stellar rotation is evident in the radial velocity of the primary component as its eclipse commences; modeling indicates this rotation is synchronous with the orbital revolution, an expected tidal effect of near-contact binary systems.

scholarly journals Spot evolution in the eclipsing binary CoRoT 105895502

2019 ◽  
Vol 623 ◽  
pp. A107 ◽  
Author(s):  
S. Czesla ◽  
S. Terzenbach ◽  
R. Wichmann ◽  
J. H. M. M. Schmitt
Keyword(s):  
Light Curve ◽  
Binary Systems ◽  
Temporal Behavior ◽  
Mass Ratio ◽  
Late Type ◽  
Stellar Rotation ◽  
Orbital Inclination ◽  
Eclipsing Binary ◽  
Short Period ◽  
Curve Modeling

Stellar activity is ubiquitous in late-type stars. The special geometry of eclipsing binary systems is particularly advantageous to study the stellar surfaces and activity. We present a detailed study of the 145 d CoRoT light curve of the short-period (2.17 d) eclipsing binary CoRoT 105895502. By means of light-curve modeling with Nightfall, we determine the orbital period, effective temperature, Roche-lobe filling factors, mass ratio, and orbital inclination of CoRoT 105895502 and analyze the temporal behavior of starspots in the system. Our analysis shows one comparably short-lived (≈40 d) starspot, remaining quasi-stationary in the binary frame, and one starspot showing prograde motion at a rate of 2.3° day−1, whose lifetime exceeds the duration of the observation. In the CoRoT band, starspots account for as much as 0.6% of the quadrature flux of CoRoT 105895502, however we cannot attribute the spots to individual binary components with certainty. Our findings can be explained by differential rotation, asynchronous stellar rotation, or systematic spot evolution.

scholarly journals δ Sct-Type Pulsators in Eclipsing Binary Systems: the Case of RZ Cas

2002 ◽  
Vol 185 ◽  
pp. 102-103
Author(s):  
E. Rodríguez ◽  
V. Costa ◽  
M.J. López-González ◽  
J.M. García ◽  
S.L. Kim ◽  
...  
Keyword(s):  
Binary System ◽  
Binary Systems ◽  
Hot Spot ◽  
Primary Component ◽  
Roche Lobe ◽  
Light Curves ◽  
Eclipsing Binary ◽  
Preliminary Results ◽  
The Impact

AbstractRZ Cas is an Algol-type eclipsing binary system where the primary component was recently discovered as a δ Set pulsator. A three-continent multisite photometric campaign was carried out during 1999. Preliminary results are reported here indicating a semi-detached system where the secondary fills its Roche lobe. The light curves also suggest a hot spot on the surface of the primary component as a consequence of the impact of the mass stream from the secondary. The pulsational behaviour can be well described with only one frequency.

scholarly journals The multiple system Sk-67°18 in the LMC

1995 ◽  
Vol 163 ◽  
pp. 251-253 ◽  
Author(s):  
V. S. Niemela ◽  
W. Seggewiss ◽  
A. F. J. Moffat
Keyword(s):  
Binary System ◽  
Radial Velocity ◽  
Spectral Type ◽  
Orbital Period ◽  
Large Magellanic Cloud ◽  
Primary Component ◽  
Magellanic Cloud ◽  
Bright Star ◽  
High Mass ◽  
Eclipsing Binary

The bright star Sk—67°18 (Brey 5) in the Large Magellanic Cloud (LMC) contains an eclipsing binary system. Our radial velocity study reveals that the orbital period is almost exactly two days. The spectra also show that the star's primary component is not of spectral type WN, but that the star is rather an Of+O type binary where the primary is probably of type O3f*. Furthermore, Sk—67°18 appears to be a high-mass multiple system.

scholarly journals EPIC 216747137: a new HW Vir eclipsing binary with a massive sdOB primary and a low-mass M-dwarf companion

2020 ◽  
Vol 500 (2) ◽  
pp. 2461-2474
Author(s):  
R Silvotti ◽  
V Schaffenroth ◽  
U Heber ◽  
R H Østensen ◽  
J H Telting ◽  
...  
Keyword(s):  
Second Life ◽  
Rotational Velocity ◽  
Stellar Rotation ◽  
Eclipsing Binary ◽  
Common Envelope ◽  
Small Subgroup ◽  
Strong Reflection ◽  
Orbital Revolution ◽  
Low Mass ◽  
M Dwarf

ABSTRACT EPIC 216747137 is a new HW Virginis system discovered by the Kepler spacecraft during its K2 ‘second life’. Like the other HW Vir systems, EPIC 216747137 is a post-common-envelope eclipsing binary consisting of a hot subluminous star and a cool low-mass companion. The short orbital period of 3.87 h produces a strong reflection effect from the secondary (∼9 per cent in the R band). Together with AA Dor and V1828 Aql, EPIC 216747137 belongs to a small subgroup of HW Vir systems with a hot evolved sdOB primary. We find the following atmospheric parameters for the hot component: Teff = 40400 ± 1000 K, log g = 5.56 ± 0.06, and log(N(He)/N(H)) = −2.59 ± 0.05. The sdOB rotational velocity v sin  i = 51 ± 10 km s−1 implies that the stellar rotation is slower than the orbital revolution and the system is not synchronized. When we combine photometric and spectroscopic results with the Gaia parallax, the best solution for the system corresponds to a primary with a mass of about 0.62 M⊙ close to, and likely beyond, the central helium exhaustion, while the cool M-dwarf companion has a mass of about 0.11 M⊙.

Distribution of physical parameters for 380 contact binaries in the Kepler field

2020 ◽  
Vol 72 (6) ◽  
Author(s):  
Xu-Zhi Li ◽  
Liang Liu ◽  
Li-Ying Zhu
Keyword(s):  
Binary Systems ◽  
Large Mass ◽  
Eclipsing Binaries ◽  
Physical Parameters ◽  
Mass Ratio ◽  
Eclipsing Binary ◽  
Contact Binaries ◽  
Contact Binary ◽  
Low Mass ◽  
Low Mass Ratio

Abstract We present the physical parameters (p, T, q, i, f) of 380 Kepler contact binary systems (hereafter called CBs). A statistical study on the CBs is carried out based on a Kepler photometric database. Our samples were selected from the Kepler Eclipsing Binary Catalogue of EW-type eclipsing binaries with periods around 0.2–1 d and amplitudes greater than $5\%$. The physical parameters were obtained by fitting the Kepler light curves with the Wilson–Devinney eclipsing binary modeling program. Our sample of CBs contains 160 A-type and 220 W-type CBs. The fill-out factor distribution indicated that CBs generally have shallow fill-out; the proportion of CBs with fill-out factors less than $30\%$ is around $70\%$, which may be related to the formation and evolution of the CBs. The period–temperature relationship of CBs is consistent with previous studies, which is the well-known period–color relationship. The distribution between mass ratio and fill-out factor can provide some information for studying the deep, low-mass ratio contact binaries and CBs which have a large mass ratio. The mass–radius diagram shows that there is a similar linear relationship between the primary and secondary stars while the primary stars are located almost on the ZAMS line; this could be related to the internal nuclear reaction within the primary and secondary stars.

scholarly journals Determination of Stellar Rotational Velocities

1985 ◽  
Vol 111 ◽  
pp. 163-184
Author(s):  
Arne Slettebak
Keyword(s):  
Radial Velocity ◽  
Line Profile ◽  
Binary Systems ◽  
Profile Analysis ◽  
Axial Rotation ◽  
Line Profile Analysis ◽  
Eclipsing Binary ◽  
Rotating Star

The three basic methods for measuring axial rotation of stars had been suggested before the beginning of this century. These are (1) Modulation of starlight due to dark or bright areas on a rotating star; (2) Distortions in the radial velocity curves of eclipsing binary systems; and (3) Line profile analysis. Research in each of these areas is reviewed.

scholarly journals KIC 8553788: A pulsating Algol with an extreme mass ratio

2018 ◽  
Vol 616 ◽  
pp. A130 ◽  
Author(s):  
A. Liakos
Keyword(s):  
Radial Velocity ◽  
Spectral Type ◽  
Primary Component ◽  
Photometric Data ◽  
Light Curves ◽  
Secondary Component ◽  
Mass Ratio ◽  
Eclipsing Binary ◽  
Detached Binaries ◽  
Absolute Parameters

Context. The present research paper focuses on the eclipsing binary KIC 8553788 which belongs to two different types of binary systems regarding its physical properties. In particular, it is one of the 71 oscillating stars of Algol-type that have been discovered so far and one of the six that have been published based on high-cadence photometric data of the Kepler mission. In addition, it is one of the four semi-detached binaries of the group of R CMa-type systems, while its pulsating component has the fourth fastest frequency among the δ Scuti stars-members of semi-detached binaries. Detailed light curves as well as spectroscopic and pulsation analyses are presented, while possible explanation scenarios for the evolution of the system involving past mass transfer, mass loss, and/or angular momentum loss due to the presence of a tertiary component are discussed. Aims. The goal of the study is to extract the pulsational characteristics of the oscillating star of the system, to estimate the absolute parameters of its components, and to provide a possible explanation for its extreme evolutionary status. Methods. Ground-based spectroscopic observations using the 2.3 m “Aristarchos” telescope were obtained and used for the estimation of the spectral type of the primary component and to model the light curves of the system with higher certainty. The short-cadence photometric data provided by the Kepler mission were analysed using standard eclipsing binary modelling techniques, while Fourier analysis was applied on their residuals aiming to reveal the properties of the intrinsic oscillations. The resulting photometric model was combined with a published radial velocity curve to obtain accurate absolute parameters for the components of the system. Results. The results show that the primary component of the system is of A8 spectral type, has a mass of 1.6 M⊙, and a radius of 2 R⊙. It is a relatively fast pulsator of δ Scuti type that oscillates in 89 frequency modes with the dominant one being 58.26 cycles day−1. On the other hand, the secondary component has a mass of only 0.07 M⊙, a radius of 1 R⊙, and a temperature of 4400 K. In addition, it was found to be magnetically active with migrating cool spots on its surface. Conclusions. KIC 8553788, according to its geometrical configuration and its pulsational properties, belongs to the group of oscillating stars of Algol type, while according to its very low mass ratio and its relatively short orbital period belongs also to the group of R CMa stars. If confirmed by radial velocity data of the secondary component, the system would have the lowest mass ratio that has ever been found in semi-detached systems and could therefore be considered as one of the most extreme cases.

scholarly journals BEER analysis of Kepler and CoRoT light curves – V. eBEER: extension of the algorithm to eccentric binaries

2020 ◽  
Vol 497 (4) ◽  
pp. 4884-4895
Author(s):  
M Engel ◽  
S Faigler ◽  
S Shahaf ◽  
T Mazeh
Keyword(s):  
Light Curve ◽  
Radial Velocity ◽  
Binary Systems ◽  
Light Curves ◽  
Harmonic Series ◽  
Eclipsing Binary ◽  
Fast Processing

ABSTRACT We present an extension of the BEER model for eccentric binaries – eBEER, approximating the BEaming, Ellipsoidal, and Reflection effects by harmonic series of the Keplerian elements of their orbit. As such, it can be a tool for fast processing of light curves for detecting non-eclipsing eccentric binary systems. To validate the applicability of the eccentric model and its approximations, we applied eBEER to the Kepler light curves, identified a sample of bright non-eclipsing binary candidates, and followed three of them with the Wise observatory eShel spectrograph. After confirming the three systems are indeed radial velocity (RV) binaries, we fitted the light curves and the RV data with PHOEBE, a detailed numerical light curve and RV model, and showed that the PHOEBE derived parameters are similar to those obtained by the eBEER approximation.

The Eclipsing Binary WX Eridani

1979 ◽  
Vol 46 ◽  
pp. 385
Author(s):  
M.B.K. Sarma ◽  
K.D. Abhankar
Keyword(s):  
Light Curve ◽  
Spectral Type ◽  
Orbital Period ◽  
Primary Component ◽  
Light Curves ◽  
Absorption Feature ◽  
Primary Star ◽  
Eclipsing Binary ◽  
The Times ◽  
Phase Angles

AbstractThe Algol-type eclipsing binary WX Eridani was observed on 21 nights on the 48-inch telescope of the Japal-Rangapur Observatory during 1973-75 in B and V colours. An improved period of P = 0.82327038 days was obtained from the analysis of the times of five primary minima. An absorption feature between phase angles 50-80, 100-130, 230-260 and 280-310 was present in the light curves. The analysis of the light curves indicated the eclipses to be grazing with primary to be transit and secondary, an occultation. Elements derived from the solution of the light curve using Russel-Merrill method are given. From comparison of the fractional radii with Roche lobes, it is concluded that none of the components have filled their respective lobes but the primary star seems to be evolving. The spectral type of the primary component was estimated to be F3 and is found to be pulsating with two periods equal to one-fifth and one-sixth of the orbital period.

scholarly journals X-ray and UV emission of the ultrashort-period, low-mass eclipsing binary system BX Trianguli

2018 ◽  
Vol 619 ◽  
pp. A138
Author(s):  
V. Perdelwitz ◽  
S. Czesla ◽  
J. Robrade ◽  
T. Pribulla ◽  
J. H. M. M. Schmitt
Keyword(s):  
Binary System ◽  
Light Curve ◽  
Binary Systems ◽  
Uv Light ◽  
Close Binary ◽  
Eclipsing Binary ◽  
X Ray ◽  
Uv Emission ◽  
Low Mass ◽  
Orbital Modulation

Context.Close binary systems provide an excellent tool for determining stellar parameters such as radii and masses with a high degree of precision. Due to the high rotational velocities, most of these systems exhibit strong signs of magnetic activity, postulated to be the underlying reason for radius inflation in many of the components. Aims.We extend the sample of low-mass binary systems with well-known X-ray properties. Methods.We analyze data from a singular XMM-Newton pointing of the close, low-mass eclipsing binary system BX Tri. The UV light curve was modeled with the eclipsing binary modeling tool PHOEBE and data acquired with the EPIC cameras was analyzed to search for hints of orbital modulation. Results.We find clear evidence of orbital modulation in the UV light curve and show that PHOEBE is fully capable of modeling data within this wavelength range. Comparison to a theoretical flux prediction based on PHOENIX models shows that the majority of UV emission is of photospheric origin. While the X-ray light curve does exhibit strong variations, the signal-to-noise ratio of the observation is insufficient for a clear detection of signs of orbital modulation. There is evidence of a Neupert-like correlation between UV and X-ray data.

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