Earth
Changes TV
www.earthchangestv.com
|
Your One Daily Source
for Earth Change News
|
|
To
print: Click
here or
Select File and then Print from your browser's menu
Translate this page automatically. 
| Month
Day,2003 |
|
Two
Dwarf Novae Undergoing Rare Outbursts
|
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
|
|
|