2007A&A...469..285V


C.D.S. - SIMBAD4 rel 1.7 - 2021.02.27CET00:19:20

2007A&A...469..285V - Astronomy and Astrophysics, volume 469, 285-296 (2007/7-1)

Absolute dimensions of eclipsing binaries. XXV. U Ophiuchi and the evolution and composition of 5 M stars.

VAZ L.P.R., ANDERSEN J. and CLARET A.

Abstract (from CDS):

Precise stellar masses and radii provide unique information on stellar evolution. In a Galactic context, they may also provide information on the evolution of the Solar neighbourhood. We aim to determine absolute dimensions for the mid B-type eclipsing binary U Ophiuchi and compare the inferred ages and chemical compositions to those of other binary stars with masses near 5M. We determine masses, radii, logg, logTeff, and luminosities for the stars in U Oph from new radial velocities and uvby light curves. By improving the Wilson-Devinney code, we also derive precise apsidal-motion and light-time orbits of this triple system, using 353 times of minimum over 120 years. Finally, we compare the data for U Oph and three similar systems with the predictions of stellar models. The stars in U Oph have masses of 5.27±0.09M and 4.74±0.07M, radii of 3.48±0.02R and 3.11 ±0.03R; we argue that systematic errors are negligible. The apsidal motion period is exceptionally short, U∼21yr, while the light-time orbit has P3∼38.4yr. The precise logg values for DI Her, U Oph, V760 Sco, and MU Cas, all within 10% of 5M, place them successively from the ZAMS to the TAMS, at ages of 5-100x106yr. Current stellar evolution models fit both stars in each system very well if the (otherwise unconstrained) metal abundance Z is adjusted in each case. More accurate data and/or binary systems with larger mass ratios are needed to actually test stellar models near 5M. The different Z values found for these young, nearby systems suggest that disk stars form with a range of metal abundances even today, but more data are needed to confirm this result.

Abstract Copyright:

Journal keyword(s): stars: binaries: eclipsing - stars: fundamental parameters - stars: evolution - Galaxy: evolution

VizieR on-line data: <Available at CDS (J/A+A/469/285): table5.dat>

Simbad objects: 9

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Number of rows : 9

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2021
#notes
1 * mu. Cas SB* 01 08 16.39470 +54 55 13.2264 5.93 5.86 5.17 4.55 4.13 G5Vb 550 1
2 V* V760 Sco Al* 16 24 43.7186408435 -34 53 37.535017356   7.16 7.05     B4V 151 0
3 HD 154445 * 17 05 32.2588605026 -00 53 31.438713756 5.10 5.73 5.61 5.39 5.34 B1V 239 0
4 HD 154895 ** 17 08 13.6540932638 -01 04 46.081839239       7.45   A1V 70 0
5 HD 156208 Al* 17 16 14.2606393919 +02 11 10.328463925 6.57 6.41 6.18 5.98   A1IV 65 0
6 V* U Oph Al* 17 16 31.7132736201 +01 12 37.996480495   5.941 5.921     B3V 369 1
7 HD 156539 PM* 17 18 04.9389110735 +03 08 49.592647226   7.26 6.86     F3V 25 0
8 HD 165208 * 18 06 08.8341947197 -31 14 34.211235597   8.97 8.83     A3III/IV 5 0
9 V* DI Her Al* 18 53 26.2400114975 +24 16 40.792385926   8.46 8.47     B5III 245 0

    Equat.    Gal    SGal    Ecl

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