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NAM2012 - All Presentation Details

Record 722 of 756

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Exposed red giant cores in eclipsing binary stars from the WASP archive

Author: Pierre Maxted

Keele University

Co-Authors: S. Geier (Bamberg); U. Heber (Bamberg); T.R. Marsh (Warwick); B. Smalley (Keele); R. Ostensen (Leuven); S. Bloemen (Leuven)

Session: STA2: Binary Stars: Duplicity is Everywhere

Presentation type: Talk      11:00  Thursday 29th 10:00-11:15 


We have identified 16 eclipsing binary stars in the WASP archive in which an apparently normal A-/F-type star eclipses a very unusual star with a typical mass of about 0.2 solar masses, effective temperature Teff = 9,000-14,000K and luminosity of a few solar luminosities. These are shell-hydrogen burning stars which have lost >80% of their mass by Roche-lobe overflow onto the companion star, i.e., progenitors of the eclipsing hot white dwarf binaries discovered using Kepler photometry. The new systems can be studied in great detail because they are bright (V=10-13), there is no on-going mass transfer, the eclipses are total and features from both stars can be seen in the observed spectrum. This makes it possible to measure the masses and radii of both stars to +-2% and to measure the effective temperature and composition of both stars. These are the only stars for which models for the formation of low mass white dwarfs (such as companions to milli-second pulsars) can be tested at this level of detail. We will present first results from a detailed study of J0247-25, the first such binary discovered, and follow-up spectroscopy for some of the 15 newly discovered binaries.

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