Absolute dimensions of eclipsing binaries. XXVI.. Setting a new standard: Masses, radii, and abundances for the F-type systems AD Bootis VZ Hydrae, and WZ Ophiuchi
Abstract
Context: Accurate mass, radius, and abundance determinations from binaries provide important information on stellar evolution, fundamental to central fields in modern astrophysics and cosmology.
Aims: We aim to determine absolute dimensions and abundances for the three F-type main-sequence detached eclipsing binaries AD Boo, VZ Hya, and WZ Oph and to perform a detailed comparison with results from recent stellar evolutionary models.
Methods: uvby light curves and uvbyβ standard photometry were obtained with the Strömgren Automatic Telescope at ESO, La Silla, radial velocity observations at CfA facilities, and supplementary high-resolution spectra with ESO's FEROS spectrograph. State-of-the-art methods were applied for the analyses: the EBOP and Wilson-Devinney binary models, two-dimensional cross-correlation and disentangling, and the VWA abundance analysis tool.
Results: Masses and radii that are precise to 0.5-0.7% and 0.4-0.9%, respectively, have been established for the components, which span the ranges of 1.1 to 1.4 M⊙ and 1.1 to 1.6 R⊙. The [Fe/H] abundances are from -0.27 to +0.10, with uncertainties between 0.07 and 0.15 dex. We find indications of a slight α-element overabundance of [α/Fe] ∼ + 0.1 for WZ Oph. The secondary component of AD Boo and both components of WZ Oph appear to be slightly active. Yale-Yonsai and Victoria-Regina evolutionary models fit the components of AD Boo and VZ Hya almost equally well, assuming coeval formation, at ages of about 1.75/1.50 Gyr (AD Boo) and 1.25/1.00 Gyr (VZ Hya). BaSTI models, however, predict somewhat different ages for the primary and secondary components. For WZ Oph, the models from all three grids are significantly hotter than observed. A low He content, decreased envelope convection coupled with surface activity, and/or higher interstellar absorption would remove the discrepancy, but its cause has not been definitively identified.
Conclusions: We have demonstrated the power of testing and comparing recent stellar evolutionary models using eclipsing binaries, provided their abundances are known. The strongest limitations and challenges are set by T_eff and interstellar absorption determinations, and by their effects on and correlation with abundance results.
- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- September 2008
- DOI:
- 10.1051/0004-6361:200809671
- arXiv:
- arXiv:0806.3218
- Bibcode:
- 2008A&A...487.1095C
- Keywords:
-
- stars: evolution;
- stars: fundamental parameters;
- stars: binaries: close;
- stars: binaries: eclipsing;
- techniques: photometric;
- techniques: spectroscopic;
- Astrophysics
- E-Print:
- Only revision is: Bottom lines (hopefully) not truncated anymore. Accepted for publication in Astronomy and Astrophysics