Dr Alon Retter (University of Sydney)

Precessing Accretion Discs in Binary Systems - Dr Alon Retter Colloquium

ATNF Marsfield Lecture Theatre

Abstract

The presence of `superhumps' (quasi-periodicities, a few percent
different from the orbital period) in the light curves of many
semi-detached binary systems is well understood by the precession
of an elliptical accretion disc. I'll summarize the current status
of the observations and theory on superhumps in cataclysmic variables
(white dwarf-red dwarf pairs) and low mass X-ray binaries (whose
primaries are neutron stars / black holes). Superhumps are important
as they can be used to estimate the binary masses. I'll show that
the theory was wrong concerning the re-establishment of the accretion
disc after the nova outburst. I'll present the discovery of the longest
known superhump period. Finally, I'll put an end to the long debate
on the nature of one of the most intriguing low mass X-ray binaries,
shed light on the mechanism for superhumps in the X-ray and present a
new confusing relation for superhumps