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By Taichi Kato
On
2001 Apr. 24.9049 UT, Christopher Jones (UK) discovered a rare outburst of DV
UMa, a variable star belonging to a rare class of eclipsing SU UMa type dwarf
novae. Gary Poyner (UK) also independently detected the outburst.
Dwarf
novae are short-period (usually 1.3 to 12 hours) binary systems composed of white
dwarfs and orbiting red dwarfs. In very lucky cases, when the orbital plane is
seen edge-on, the red dwarf eclipses the central white dwarf and the surrounding
accretion disk in every orbit. Since dwarf novae sometimes erupt (outbursts),
detailed observation of eclipses during outburst provides crucial information
why dwarf novae erupt.
There are only a handful of this class of such systems.
Especially important are eclipsing SU UMa-type systems, which show both normal
outbursts (short outbursts) and superoutbursts (very bright, long outbursts).
The existence of these two types of outbursts has puzzled many astronomers for
these thirty years, and has been one of central topics in researchers of cataclysmic
variables.
Previously reported outbursts of DV UMa are 1995 Feb. (normal
outburst), 1997 Apr. (superoutburst) and 1999 Dec. (superoutburst), all of which
have result rich results leading to our better understanding to outbursting dwarf
nova disks, some of which are already published as scientific papers.
The
1999 Dec. superoutburst was very well observed by the VSNET collaboration team,
and the data are being intensively analyzed using the recently developed computational
techinque, and will be compared with theories. The summary of the 1999 observation
cal be seen at the URL below.
http://www.kusastro.kyoto-u.ac.jp/vsnet/DNe/dvuma9912.html |
