[vsnet-alert 7620] XZ Eri: superoutburst of the eclipsing SU UMa-type dwarf nova!

[Taichi Kato <tkato@kusastro.kyoto-u.ac.jp>]

XZ Eri: superoutburst of the eclipsing SU UMa-type dwarf nova!

Dear Colleagues,

   We have just received observations from Greg Bolt (Jan. 28).
The data clearly show the presence of ~0.4 mag superhumps (having the
most likely period slightly longer than the orbital period).

   The data also show shallow eclipses, which resemble the eclipses
observed during the first night of a superoutburst of DV UMa (see
http://vsnet.kusastro.kyoto-u.ac.jp/vsnet/DNe/dvuma9912.html ).
It is likely that either the maximum expansion of the disk or the slightly
low orbital inclination is responsible for the shallow eclipses.
Anyway, XZ Eri is now established to be an eclipsing SU UMa-type dwarf
nova (UGSU+E)!  Among eclipsing SU UMa-type dwarf novae, XZ Eri has
the shortest orbital period (except for the shallow eclipser WZ Sge).
SU UMa-type dwarf novae with similar orbital periods are known to
show unusual features, such as post-superoutburst rebrihtening, increase
of the superhump periods, regrowth of the superhump amplitude during the
late stage of superoutbursts, etc.  The discovery of an eclipsing object
in this period region will provide us important clues to understand
these still poorly understood phenomena, by applying spatial resolution
techniques (e.g. eclipse mapping) to the outbursting or superhumping
accretion disk.

   We have also received reports of successful observations from Torii-san
(RIKEN), Tanabe-san (VSNET Okayama Station), and naturally by the
Kyoto team.  We will soon be analyzing the entire data.  Further observations
are *most definitely* encouraged!!

   We will prepare a VSNET page in due time
  (will be http://vsnet.kusastro.kyoto-u.ac.jp/vsnet/DNe/xzeri.html).  Please
visit this page and share the wonder of the cataclysmic variable!

Regards,
Taichi Kato
VSNET Collaboration team

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