Disentangling cataclysmic variables in Gaia's HR diagram

Abstract

Cataclysmic variables (CVs) are interacting binaries consisting of at least three components that control their colour and magnitude. Using Gaia, we here investigate the influence of the physical properties of these binaries on their position in the Hertzsprung-Russell (HR) diagram. The CVs are on average located between the main sequence and the white dwarf regime, the maximum density being at G_BP - G_RP ∼ 0.56 and G_abs ∼ 10.15. We find a trend of the orbital period with colour and absolute brightness: with decreasing period, the CVs become bluer and fainter. We also identify the location of the various CV subtypes in the HR diagram and discuss the possible location of detached CVs, going through the orbital period gap.