On the Binary Nature of Dust-encircled BD +20 307

Published 2008 May 1 © 2008. The American Astronomical Society. All rights reserved. Printed in U.S.A.
, , Citation A. J. Weinberger 2008 ApJ 679 L41 DOI 10.1086/589180

1538-4357/679/1/L41

Abstract

Three epochs of high-resolution spectra of the star BD +20 307 show that it is a short-period (~3.4 day) spectroscopic binary of two nearly identical stars. Surprisingly, the two stars, although differing in effective temperature by only ~250 K and having a mass ratio of 0.91, show very different Li line equivalent widths. A Li 6707 Å line is detected from only the primary star, and it is weak. This star is therefore likely to be older than 1 Gyr. If so, the large amount of hot circumbinary dust must be from a very large and recent, but very late evolutionarily, collision of planetesimals.

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10.1086/589180