A&A 434, L13-L16 (2005)
DOI: 10.1051/0004-6361:200500102
Letter
Identification of 13 DB + dM and 2 DC + dM binaries from the Sloan Digital Sky Survey
E. J. M. van den Besselaar1, G. H. A. Roelofs1, G. A. Nelemans1, T. Augusteijn2 and P. J. Groot11 Department of Astrophysics, Radboud University Nijmegen, PO Box 9010, 6500 GL Nijmegen, The Netherlands
e-mail: [besselaar;gijsroel;nelemans;pgroot]@astro.ru.nl
2 Nordic Optical Telescope, Apartado 474, Santa Cruz de La Palma, Spain
e-mail: tau@not.iac.es
(Received 5 January 2005 / Accepted 22 March 2005)
Abstract
We present the identification of 13 DB + dM binaries and 2 DC + dM binaries from the Sloan Digital Sky Survey (SDSS). Before the SDSS only 2 DB + dM binaries and 1 DC + dM binary were known. At least three, possibly 8, of the new DB + dM binaries seem to have white dwarf temperatures well above 30 000 K which would place them in the so called DB-gap. Finding these DB white dwarfs in binaries may suggest that they have formed through a different evolutionary channel
than the ones in which DA white dwarfs transform into DB white dwarfs due to convection in the upper layers.
Key words: binaries: spectroscopic -- white dwarfs -- stars: late-type -- stars: evolution
SIMBAD Objects
© ESO 2005
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