The population of AM CVn stars from the Sloan Digital Sky Survey

Understand

The AM Canum Venaticorum stars are rare interacting white dwarf binaries, whose formation and evolution are still poorly known.

• The Sloan Digital Sky Survey provides, for the first time, a sample of 6 AM CVn stars (out of a total population of 18) that is sufficiently homogeneous that we can start to study the population in some detail.
• We use the Sloan sample to `calibrate' theoretical population synthesis models for the space density of AM CVn stars.
• We consider optimistic and pessimistic models for different theoretical formation channels, which yield predictions for the local space density that are more than two orders of magnitude apart.