(cba:news) cba preprint - v803 cen

[Jonathan Kemp]

A new CBA Preprint on V803 Centauri can now be found on the publications
page of the CBA web site.

          www.cbastro.org/publications

Regards,

Jonathan

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V803 Centauri, A Helium-Rich Dwarf Nova
Joseph Patterson, Stan Walker, Jonathan Kemp, Darragh O'Donoghue, and Marc Bos
Publications of the Astronomical Society of the Pacific
(submitted, December 1999)

We report 1992-1999 photometry of the helium-rich cataclysmic variable
V803 Centauri.  In its high-brightness state at V=13, the star shows a
strong periodic signal with P=1618 s;  this resembles the superhumps
associated with many dwarf novae.  However, it is unusual because the
superhump endures through all brightness states, including the very faint
state at V=17.  The star also becomes occasionally stuck in a "cycling
state", in which the brightness varies in the range 13.4-14.5, with a
period of 0.98 d.  This appears to be the recurrence pattern of "normal"
dwarf-nova outbursts.  Thus the underlying physics is probably that of a
dwarf nova, but with an accretion disk dominated by helium.

Reckoned as a dwarf nova, V803 Cen presents an interesting test for
accretion disk theory, because it appears to display two timescales for
eruption recurrence:  0.94 d at V=14.5, and ~5 d at V=17.2.  This is
roughly consistent with the general idea that recurrence time scales
inversely with accretion rate.