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, logT
eff, 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 P
3∼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 5-100x10
6yr. 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
Full paper
View the references in ADS
To bookmark this query, right click on this link: simbad:2007A&A...469..285V and select 'bookmark this link' or equivalent in the popup menu