Population types of cataclysmic variables in the solar neighbourhood

Abstract

The Galactic orbital parameters of 159 cataclysmic variables in the Solar neighbourhood are calculated, for the first time, to determine their population types using published kinematical parameters. Population analysis shows that about 6% of cataclysmic variables in the sample are members of the thick disc component of the Galaxy. This value is consistent with the fraction obtained from star count analysis. The rest of the systems in the sample are found to be in the thin disc component of the Galaxy. Our analysis revealed no halo CVs in the Solar vicinity. About 60% of the thick disc CVs have orbital periods below the orbital period gap. This result is roughly consistent with the predictions of population synthesis models developed for cataclysmic variables. A kinematical age of 13 Gyr is obtained using total space velocity dispersion of the most probable thick disc CVs which is consistent with the age of thick disc component of the Galaxy. (C) 2012 Elsevier B.V. All rights reserved.