scholarly journals Analysis of the Hipparcos Sample of Eclipsing Binaries Parallaxes And Multiplicity

1998 ◽  
Vol 11 (1) ◽  
pp. 569-569
Author(s):  
E. Oblak ◽  
M. Kurpinska-Winiarska ◽  
T. Kundera ◽  
S. Zola ◽  
T.Z. Dworak
Keyword(s):  
Main Sequence ◽  
Eclipsing Binaries ◽  
Main Sequence Stars ◽  
Eclipsing Binary ◽  
Visual Component ◽  
Inadequate Knowledge ◽  
Two Systems ◽  
Trigonometric Parallaxes ◽  
Good Agreement

The Hipparcos astrometric satellite observed 993 known eclipsing binaries. Prom 1048 eclipsing binaries of the Brancewicz and Dworak ’s catalogue (1980), there are only 368 observed by Hipparcos, as the others are too faint. On the basis of these common stars, we have undertaken the comparison ofthe satellite parallaxes with the photometric ones. We obtain a good agreement between the two systems with a mean dispersion of 5 mas. The greatest dispersion is for the goup of eclipsing binaries of the EW type. The eclipsing binaries of this group have a mass-luminosity relation different from those of the main sequence stars. An inadequate knowledge of the component spectra of an eclipsing binary seems to be one of the most important cause of discrepancies. For some brightest stars, the new Hipparcos trigonometric parallaxes differ very significantly from those previously known from ground based measurements. It seems that the presence of a close visual components causes statistically an underestimation of photometric or overestimation of Hipparcos parallaxes. 172 Hipparcos eclipsing binaries have a close visual component, generally less than 10 arcseconds apart. The list of these stars for various stellar groups and a brief analysis are presented.

scholarly journals Eclipsing binary stars as tests of stellar evolutionary models and stellar ages

2008 ◽  
Vol 4 (S258) ◽  
pp. 161-170 ◽  
Author(s):  
Keivan G. Stassun ◽  
Leslie Hebb ◽  
Mercedes López-Morales ◽  
Andrej Prša
Keyword(s):  
Binary Stars ◽  
Main Sequence ◽  
Magnetic Activity ◽  
Eclipsing Binaries ◽  
Evolutionary Models ◽  
Main Sequence Stars ◽  
Eclipsing Binary ◽  
Eclipsing Binary Stars ◽  
Sequence Components ◽  
Low Mass

AbstractEclipsing binary stars provide highly accurate measurements of the fundamental physical properties of stars. They therefore serve as stringent tests of the predictions of evolutionary models upon which most stellar age determinations are based. Models generally perform very well in predicting coeval ages for eclipsing binaries with main-sequence components more massive than ≈1.2 M⊙; relative ages are good to ~5% or better in this mass regime. Low-mass main-sequence stars (M < 0.8 M⊙) reveal large discrepancies in the model predicted ages, primarily due to magnetic activity in the observed stars that appears to inhibit convection and likely causes the radii to be 10–20% larger than predicted. In mass-radius diagrams these stars thus appear 50–90% older or younger than they really are. Aside from these activity-related effects, low-mass pre–main-sequence stars at ages ~1 Myr can also show non-coevality of ~30% due to star formation effects, however these effects are largely erased after ~10 Myr.

scholarly journals Empirical bolometric correction coefficients for nearby main-sequence stars in the Gaia era

2020 ◽  
Vol 496 (3) ◽  
pp. 3887-3905 ◽  
Author(s):  
Z Eker ◽  
F Soydugan ◽  
S Bilir ◽  
V Bakış ◽  
F Aliçavuş ◽  
...  
Keyword(s):  
Main Sequence ◽  
Eclipsing Binaries ◽  
The Other ◽  
Accurate Data ◽  
Quadratic Relation ◽  
Main Sequence Stars ◽  
Data Release ◽  
Trigonometric Parallaxes ◽  
Bolometric Correction ◽  
Intrinsic Colour

ABSTRACT Nearby detached double-lined eclipsing binaries with most accurate data were studied and 290 systems were found with at least one main-sequence component having a metallicity of 0.008 ≤ Z ≤ 0.040. Stellar parameters, light ratios, Gaia Data Release 2 trigonometric parallaxes, extinctions and/or reddening were investigated and only 206 systems were selected as eligible to calculate empirical bolometric corrections. NASA/IPAC Galactic dust maps were the main source of extinctions. Unreliable extinctions at low Galactic latitudes |b| ≤ 5° were replaced with individual determinations, if they exist in the literature, else associated systems were discarded. The main-sequence stars of te remaining systems were used to calculate the bolometric corrections (BCs) and to calibrate the BC–Teff relation, which is valid in the range 3100–36 000 K. De-reddened (B − V)0 colours, on the other hand, allowed us to calibrate two intrinsic colour–effective temperature relations; the linear one is valid for $T_{\rm eff}\gt 10\, 000$ K, while the quadratic relation is valid for $T_{\rm eff}\lt 10\, 000$ K; that is, both are valid in the same temperature range in which the BC–Teff relation is valid. New BCs computed from Teff and other astrophysical parameters are tabulated, as well.

scholarly journals A preliminary color-magnitude diagram for late-type stars in the solar neighborhood

1959 ◽  
Vol 10 ◽  
pp. 39-40
Author(s):  
O. C. Wilson
Keyword(s):  
Main Sequence ◽  
Star Clusters ◽  
Solar Neighborhood ◽  
Late Type ◽  
Main Sequence Stars ◽  
Individual Values ◽  
Magnitude Diagram ◽  
Trigonometric Parallaxes ◽  
Nearby Stars ◽  
The Mean

Modern photoelectric techniques yield magnitudes and colors of stars with accuracies of the order of a few thousandths and a few hundredths of a magnitude respectively. Hence for star clusters it is possible to derive highly accurate color-magnitude arrays since all of the members of a cluster may be considered to be at the same distance from the observer. It is much more difficult to do this for the nearby stars where all of the objects concerned are at different, and often poorly determined, distances. If one depends upon trigonometric parallaxes, the bulk of the reliable individual values will refer to main sequence stars, and while the mean luminosities of brighter stars are given reasonably well by this method, the scatter introduced into a color-magnitude array by using individual trigonometrically determined luminosities could obscure important features. Somewhat similar objections could be raised against the use of the usual spectroscopic parallaxes which also should be quite good for the main sequence but undoubtedly exhibit appreciable scatter for some, at least, of the brighter stars.

scholarly journals V471 Tauri and SuWt 2: The Exotic Descendants of Triple Systems?

2002 ◽  
Vol 187 ◽  
pp. 239-243 ◽  
Author(s):  
Howard E. Bond ◽  
M. Sean O’Brien ◽  
Edward M. Sion ◽  
Dermott J. Mullan ◽  
Katrina Exter ◽  
...  
Keyword(s):  
Main Sequence ◽  
Central Star ◽  
High Mass ◽  
Eclipsing Binary ◽  
Triple Systems ◽  
Common Envelope ◽  
Short Period ◽  
Efficiency Parameter ◽  
Hydrodynamical Simulations ◽  
Good Agreement

AbstractV471 Tauri is a short-period eclipsing binary, and a member of the Hyades. It is composed of a hot DA white dwarf (WD) and a cool main-sequence dK2 companion. HST radial velocities of the WD, in combination with the ground-based spectroscopic orbit of the K star, yield dynamical masses of MWD = 0.84 and MdK = 0.93 M⊙. During the UV observations we serendipitously detected coronal mass ejections from the K star, passing in front of the WD and appearing as sudden, transient metallic absorption. Eclipse timings show that the active dK star is 18% larger than a main-sequence star of the same mass, an apparent consequence of its extensive starspot coverage. The high Teff and high mass of the WD are paradoxical: the WD is the most massive in the Hyades, but also the youngest. A plausible scenario is that the progenitor system was a triple, with a close inner pair that merged after several × 108 yr to produce a single blue straggler. When this star evolved to the AGB phase, it underwent a common-envelope interaction with a distant dK companion, which spiraled down to its present separation and ejected the envelope. The common-envelope efficiency parameter, αCE, was of order 0.3–1.0, in good agreement with recent hydrodynamical simulations.SuWt 2 is a southern-hemisphere planetary nebula (PN) with an unusual ring-shaped morphology. The central star is an eclipsing binary with a period of 4.9 days. Surprisingly, the binary is composed of two main-sequence A-type stars with similar masses of ~ 2.5 M⊙. We discuss scenarios involving a third companion which ejected and ionizes the PN.WeBo 1 is a northern PN with a ring morphology remarkably similar to that of SuWt 2. Although we hoped that its central star would shed light on the nature of SuWt 2, it has proven instead to be a late-type barium star!

scholarly journals Apsidal motion in evolved binary systems

1984 ◽  
Vol 105 ◽  
pp. 419-420
Author(s):  
Alvaro Giménez
Keyword(s):  
Preliminary Report ◽  
Binary Systems ◽  
Main Sequence ◽  
Review Paper ◽  
Theoretical Models ◽  
Eclipsing Binaries ◽  
Apsidal Motion ◽  
Different Sources ◽  
Obvious Extension ◽  
Good Agreement

The study of apsidal motions in eclipsing binaries has proven to be one of the best methods to check the internal density concentrations of the stars predicted by theoretical models. During the main sequence phase, we have found a good agreement between the observed apsidal motion rates and computer-constructed stellar models provided that a realistic consideration is made of the evolution between the lower and upper borders of the main sequence (Giménez and García-Pelayo, 1982). An obvious extension of this work is a throughout study of the more evolved evolved systems beyond the TAMS where theoretical models are less accurate and empirical data from different sources are largely needed (see review paper by Zahn in this volume). A preliminary report on such a study is presented.

Absolute parameters of three southern eclipsing binaries: DQ Car, BK Ind, and V4396 Sgr

2020 ◽  
Vol 493 (2) ◽  
pp. 2659-2675
Author(s):  
Derya Sürgit ◽  
Ahmet Erdem ◽  
Chris A Engelbrecht ◽  
Fred Marang
Keyword(s):  
South African ◽  
Binary Stars ◽  
Main Sequence ◽  
Interstellar Extinction ◽  
Eclipsing Binaries ◽  
Evolutionary Status ◽  
Distance Modulus ◽  
Main Sequence Stars ◽  
The Masses ◽  
Absolute Parameters

ABSTRACT We present combined photometric and spectroscopic analyses of the three southern eclipsing binary stars: DQ Car, BK Ind, and V4396 Sgr. Radial velocity curves of these three systems were obtained at the South African Astronomical Observatory, and their light curves from the available data bases and surveys were used for the analysis. 75 new times of minima for these three eclipsing binaries were derived, and their ephemerides were updated. Only the O–C diagram of DQ Car indicates a cyclical variation, which was interpreted in terms of the light-time effect due to a third body in the system. Our final models describe these three systems as Algol-like binary stars with detached configurations. The masses and radii were found to be M1 = 1.86(±0.17) M⊙, R1 = 1.63(±0.06) R⊙ and M2 = 1.74(±0.17) M⊙, R2 = 1.52(±0.07) R⊙ for the primary and secondary components of DQ Car; M1 = 1.16(±0.05) M⊙, R1 = 1.33(±0.03) R⊙ and M2 = 0.98(±0.04) M⊙, R2 = 1.00(±0.03) R⊙ for BK Ind; and M1 = 3.14(±0.22) M⊙, R1 = 3.00(±0.09) R⊙ and M2 = 3.13(±0.24) M⊙, R2 = 2.40(±0.08) R⊙ for V4396 Sgr, respectively. The distances to DQ Car, BK Ind, and V4396 Sgr were derived to be 701(±50), 285(±20), and 414(±30) pc from the distance modulus formula, taking into account interstellar extinction. The evolutionary status of these three systems was also studied. It has been found that the components of DQ Car are very young stars at the age of ∼25 Myr and those of BK Ind and V4396 Sgr are evolved main-sequence stars at the ages of ∼2.69 Gyr and ∼204 Myr, respectively.

scholarly journals Modelling of an Eclipsing RS CVn Binary: V405 And

2011 ◽  
Vol 7 (S282) ◽  
pp. 199-200
Author(s):  
Krisztián Vida ◽  
Katalin Oláh ◽  
Zsolt Kővári
Keyword(s):  
Light Curve ◽  
Main Sequence ◽  
Magnetic Activity ◽  
Light Curves ◽  
Stellar Structure ◽  
Main Sequence Stars ◽  
M Dwarfs ◽  
Primary Star ◽  
Convective Envelope ◽  
Eclipsing Binary

AbstractV405 And is an ultrafast-rotating (Prot ≈ 0.46 days) eclipsing binary. The system consists of a primary star with radiative core and convective envelope, and a fully convective secondary. Theories have shown that stellar structure can depend on magnetic activity, i.e., magnetically active M-dwarfs should have larger radii. Earlier light curve modelling of V405 And indeed showed this behaviour: we found that the radius of the primary is significantly larger than the theoretically predicted value for inactive main sequence stars (the discrepancy is the largest of all known objects), while the secondary fits well to the mass-radius relation. By modelling our recently obtained light curves, which show significant changes of the spotted surface of the primary, we can find further proof for this phenomenon.

scholarly journals An Improvement in the Visual Surface Brightness Scale for B5-F5 Main Sequence Stars

1985 ◽  
Vol 111 ◽  
pp. 523-524
Author(s):  
L. Pastori ◽  
G. Malaspina
Keyword(s):  
Surface Brightness ◽  
Color Index ◽  
Main Sequence ◽  
Surface Gravity ◽  
Main Sequence Stars ◽  
Interferometric Method ◽  
Gravity Effects ◽  
Good Agreement ◽  
Angular Diameters

Angular diameters of 593 B5-F5 main sequence stars listed in the “Catalogue of apparent diameters and absolute radii of stars” (CADARS; Fracassini et al. 1981) have been analysed in order to improve the precision of the visual surface brightness Sv. The new relations between this quantity and the color index (B-V)o turn out to be in good agreement with those found with the interferometric method (Barnes et al. 1978). Moreover, the results suggest that surface gravity effects may bias the Sv-(B-V)o relations.

scholarly journals The Impact of Starspots on Mass and Age Estimates for Pre-main Sequence Stars

2015 ◽  
Vol 10 (S314) ◽  
pp. 91-94
Author(s):  
Garrett Somers ◽  
Marc H. Pinsonneault
Keyword(s):  
Binary Systems ◽  
Main Sequence ◽  
Late Type ◽  
Main Sequence Stars ◽  
Eclipsing Binary ◽  
Lithium Depletion ◽  
The Impact ◽  
Age Estimates ◽  
Hr Diagram

AbstractWe investigate the impact of starspots on the evolution of late-type stars during the pre-main sequence (pre-MS). We find that heavy spot coverage increases the radii of stars by 4–10%, consistent with inflation factors in eclipsing binary systems, and suppresses the rate of pre-MS lithium depletion, leading to a dispersion in zero-age MS Li abundance (comparable to observed spreads) if a range of spot properties exist within clusters from 3-10 Myr. This concordance with data implies that spots induce a range of radii at fixed mass during the pre-MS. These spots decrease the luminosity and Teff of stars, leading to a displacement on the HR diagram. This displacement causes isochrone derived masses and ages to be systematically under-estimated, and can lead to the spurious appearance of an age spread in a co-eval population.

KIC 5359678: A detached eclipsing binary with starspots

2021 ◽  
Author(s):  
Jiaxin Wang ◽  
Jianning Fu ◽  
Hubiao Niu ◽  
Yang Pan ◽  
Chunqian Li ◽  
...  
Keyword(s):  
Main Sequence ◽  
Function Analysis ◽  
Light Curves ◽  
Main Sequence Stars ◽  
Period Range ◽  
Eclipsing Binary ◽  
A Value ◽  
Auto Correlation ◽  
Auto Correlation Function ◽  
The Masses

Abstract We study the detached eclipsing binary, KIC 5359678, with starspot modulation using the high-quality Kepler photometry and LAMOST spectroscopy. The PHOEBE model, optimal for this binary, reveals that this system is a circular detached binary, composed of two F-type main-sequence stars. The masses and radii of the primary and the secondary are M1 = 1.31 ± 0.05M⊙, R1 = 1.52 ± 0.04R⊙, M2 = 1.12 ± 0.04M⊙, and R2 = 1.05 ± 0.06R⊙, respectively. The age of this binary is estimated to be about 2Gyr, a value much longer than the synchronization timescale of 17.8 Myr. The residuals of light curves show quasi-sinusoidal signals, which could be induced by starspots. We apply auto-correlation function analysis on the out-of-eclipse residuals and find that the spot with rotational period close to the orbital period, while, the decay timescale of starspots is longer than that on the single stars with the same temperature, period range, and rms scatter. A two-starspot model is adopted to fit the signals with two-dip pattern, whose result shows that the longitude decreases with time.

Sign in / Sign up

Export Citation Format

Share Document