Abstract

From optical photometry we show that SDSS121258.25-012310.1 is a new eclipsing post common envelope binary with an orbital period of ? 8.06 hours and eclipse length of 23 minutes. From spectroscopic follow up observations we measured the semi-amplitude of the radial velocity for the secondary star, K2 181 3 kms-1. By fitting the optical SDSS spectrum we constrained the stellar parameters. The white dwarf temperature is 17700 300 K, its surface gravity log g 7.53 0.2, the spectral type of the secondary star is M4 1 and the distance to the system d 230 20 parsec. Masses are estimated to be in the range 0.25 - 0.38 M? for the red dwarf and 0.33 - 0.48 M? for the white dwarf. We finally discuss the evolutionary state of the system. © 2009 IOP Publishing Ltd.