Population types of cataclysmic variables in the solar neighbourhood

TL;DR

This study classifies the population types of 159 cataclysmic variables near the Sun using their galactic orbits, revealing their distribution among Galactic components and estimating their ages, with results aligning with existing models.

Contribution

First-time calculation of galactic orbital parameters for local CVs to determine their population membership and age, providing new insights into their distribution and characteristics.

Findings

6% of CVs are thick disc members

No halo CVs detected nearby

60% of thick disc CVs are below the orbital period gap

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 per cent 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 per cent 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.