Evolved cataclysmic variables as progenitors of AM CVn stars

Cataclysmic Variables with Evolved Secondaries and the Progenitors of AM CVn Stars

We present the results of a systematic study of cataclysmic variables (CVs) and related systems, combining detailed binary-population synthesis (BPS) models with a grid of 120 binary evolution sequences calculated with a Henyey-type stellar evolution code. In these sequences, we used 3 masses for the white dwarf (0.6, 0.8, 1.0M⊙) and seven masses for the donor star in the range of 0.6 − 1.4M⊙. ...

AM CVn stars

I review our observational and theoretical knowledge of AM CVn stars, focusing on recent developments. These include newly discovered systems, the possibility that two recently discovered extremely short period objects are AM CVn stars and an update on X-ray, UV an optical studies. Theoretical advances include the study of the details of both the donor and accretor, and the physics of the heliu...

How Evolved are the Mass Donor Stars in Cataclysmic Variables?

The outburst properties of AM CVn stars

We briefly summarize the observational properties of ultra-compact binaries called AM CVn stars. We analize their outbursts originating from the thermal-viscous instability in helium accretion disc. We present our preliminary results in applying the model of Dwarf Novae outbursts to helium discs. We can calculate models of outbursts of reasonable amplitude of 2 mag with a constant α parameter t...

The Donor Stars of Cataclysmic Variables

We carefully consider observational and theoretical constraints on the global properties of secondary stars in cataclysmic variable stars (CVs). We then use these constraints to construct and test a complete, semi-empirical donor sequence for CVs with orbital periods Porb 6 6 hrs. All key physical and photometric parameters of CV secondaries (along with their spectral types) are given as a func...