Speaker
John Cannizzo
(UMBC)
Description
The study of AM CVn stars - semi-detached He WD-WD binaries - has exploded in recent years
thanks to long term light curves obtained by the Palomar Transient Factory. Systems are seen with
binary periods ranging from about 5 minutes to about an hour. AM CVn stars are similar to dwarf novae
in that they can undergo accretion disk outbursts. Systems with high dM/dt have steady disks in
permanent outburst, whereas for very low dM/dt systems the disks are too cool to have outbursts.
Disk instability theory gives a specific prediction for the zone of instability, therefore by matching
the observed zone with the theoretical one we constrain dM/dt(P_orb), the rate of mass transfer
versus orbital period. The inferred relation is consistent with expectations from stellar evolution.
One also has predictions for the recurrence time for outbursts and outburst duration versus P_orb
which can be compared to observations.
Author
John Cannizzo
(UMBC)
Co-author
Dr
Gijs Nelemans
(Radboud Univ. Nijmegen)
