Journal
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
Volume 438, Issue 1, Pages 590-603Publisher
OXFORD UNIV PRESS
DOI: 10.1093/mnras/stt2229
Keywords
stars: abundances; binaries: eclipsing; binaries: spectroscopic; stars: chemically peculiar; stars: fundamental parameters; stars: individual: YZ Cas
Categories
Funding
- STFC
- Science and Technology Facilities Council [ST/H005307/1] Funding Source: researchfish
- STFC [ST/H005307/1] Funding Source: UKRI
Ask authors/readers for more resources
The bright binary system YZ Cassiopeiae is a remarkable laboratory for studying the Am phenomenon. It consists of a metallic-lined A2 star and an F2 dwarf on a circular orbit, which undergo total and annular eclipses. We present an analysis of 15 published light curves and 42 new high-quality echelle spectra, resulting in measurements of the masses, radii, effective temperatures and photospheric chemical abundances of the two stars. The masses and radii are measured to 0.5 per cent precision: M-A = 2.263 +/- 0.012 M-circle dot, M-B = 1.325 +/- 0.007 M-circle dot, R-A = 2.525 +/- 0.011 R-circle dot and R-B = 1.331 +/- 0.006 R-circle dot. We determine the abundance of 20 elements for the primary star, of which all except scandium are supersolar by up to 1 dex. The temperature of this star (9520 +/- 120 K) makes it one of the hottest Am stars. We also measure the abundances of 25 elements for its companion (T-eff = 6880 +/- 240 K), finding all to be solar or slightly above solar. The photospheric abundances of the secondary star should be representative of the bulk composition of both stars. Theoretical stellar evolutionary models are unable to match these properties: the masses, radii and temperatures imply a half-solar chemical composition (Z = 0.009 +/- 0.003) and an age of 490-550 Myr. YZ Cas therefore presents a challenge to stellar evolutionary theory.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available