Institut für Astronomie und Astrophysik Abteilung Astronomie Sand 1, D-72076 Tübingen, Germany
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Preprint 08/03

AA Dor -- An Eclipsing sdOB - Brown Dwarf Binary

Rauch T. (1,2)

(1) Dr.-Remeis-Sternwarte, Sternwartstraße 7, D-96049 Bamberg, Germany
(2) Institut für Astronomie und Astrophysik, Sand 1, D-72076 Tübingen, Germany

To be published in: Ap&SS

Abstract. AA Dor is an eclipsing, close, post common-envelope binary (PCEB) consisting of a sdOB primary star and an unseen secondary with an extraordinary small mass - formally a brown dwarf. The brown dwarf may have been a former planet which survived a common envelope (CE) phase and has even gained mass.
A recent determination of the components' masses from results of NLTE spectral analysis and subsequent comparison to evolutionary tracks shows a discrepancy to masses derived from radial-velocity and the eclipse curves. Phase-resolved high-resolution and high-SN spectroscopy was carried out in order to investigate on this problem.
We present results of a NLTE spectral analysis of the primary, an analysis of its orbital parameters, and discuss possible evolutionary scenarios.
 
Key words: binaries: eclipsing - common envelope - evolution - individual: AA Dor - low-mass, brown dwarfs

Preprint (167 kb PDF file including figures)

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