The outbursts properties of AM CVn stars

TL;DR

This paper reviews the observational features of AM CVn stars and models their outbursts using a helium disc instability framework, achieving realistic outburst amplitudes and superoutburst-like lightcurves.

Contribution

It applies the dwarf novae outburst model to helium accretion discs in AM CVn stars, providing preliminary results that match observed outburst characteristics.

Findings

Models produce outbursts with ~2 mag amplitude

Constant alpha parameter used in models

High mass transfer rates yield superoutburst-like lightcurves

Abstract

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 alfa parameter throughout the calculation. Setting the mass transfer rate close to its upper critical value produces model lightcurves that resemble short superoutbursts.