The long-term optical behaviour of helium-accreting AM CVn binaries

We present the results of a two and a half year optical photometric monitoring programme covering 16 AM CVn binaries using the Liverpool Telescope on La Palma. We detected outbursts in seven systems, one of which (SDSS J0129) was seen in outburst for the first time. Our study coupled with existing data shows that ~1/3 of these helium-rich accreting compact binaries show outbursts. The orbital period of the outbursting systems lie in the range 24-44 mins and is remarkably consistent with disk-instability predictions. The characteristics of the outbursts seem to be broadly correlated with their orbital period (and hence mass transfer rate). Systems which have short periods (