Volume 500, Number 2, June III 2009
|Page(s)||867 - 872|
|Section||Stellar structure and evolution|
|Published online||29 April 2009|
Post common envelope binaries from the SDSS
VI. SDSS J120615.73+510047.0: a new low accretion rate magnetic binary
Astrophysikalisches Institut Potsdam, An der Sternwarte 16, 14482 Potsdam, Germany e-mail: email@example.com
2 Departamento de Física y Astronomía, Universidad de Valparaíso, Avenida Gran Bretana 1111, Valparaíso, Chile
3 Department of Physics, University of Warwick, Coventry CV4 7AL, UK
Accepted: 18 March 2009
We report the discovery of the ninth pre-polar consisting of a late-type ZAMS secondary and a magnetic white dwarf. The white dwarf accretes at an extreme low rate, yr-1, from the wind of the companion donor star. The source was found in our systematic search for WD/MS binaries within SDSS/SEGUE. Based on seven Sloan spectra we estimate a binary period of ~200, 230, or 270 min. The UV to IR spectral energy distribution was decomposed into a dM3-dM4 ZAMS secondary and a cool white dwarf, ~9000 K, which consistently imply a distance between 360 and 420 pc. The optical spectrum displays one pronounced cyclotron hump, likely originating from a low-temperature plasma, ~1 keV, in a field of 108 MG. We comment on the evolutionary link between polars and pre-polars.
Key words: accretion, accretion disks / stars: magnetic fields / binaries: close / stars: individual: SDSS J120615.73+510047.0
© ESO, 2009
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