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[vsnet-campaign-news 80] AstroAlert: AL Com rapid recovery!
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AL Comae Berenices rapid recovery!
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As suggested in the preceding article of AstroAlert, AL Com has rapidly
recovered from the temporary fading below 16th mag on June 11.5 UT.
Jochen Pietz reported the star has brightened to 15.5 mag on 13.883 UT.
The short duration of the temporary fading strongly suggests that the
object is entering a stage of the second superoutburst (if it follows
the course of the 1995 superoutburst).
The phenomenon called as "post-superoutburst rebrightening". Detailed
observation during in such stages are cruicial in understanding the
mechanism of outbursts in extremely infrequently outbursting dwarf novae,
as in AL Com. However, the light curve of the post-superoutburst
rebrightening can be very complex. The 1995 superoutburst of AL Com
showed a brief brightening, followed by a rapid fade, and again returned
to a long-lasting bright state, which showed day-scale modulations.
The entire picture of such a post-superoutburst rebrightening is not
still well understood.
A different example of repetetive rebrightening was seen in EG Cnc.
(See the URL shown below)
Observations at this stage is extremely important. Please make
time-resolved (CCD) photometry as long as possible.
Related URLs on VSNET:
http://vsnet.kusastro.kyoro-u.ac.jp/vsnet/DNe/alcom0105.html (current outburst)
http://vsnet.kusastro.kyoro-u.ac.jp/vsnet/DNe/alcom1.html (1995 outburst)
http://vsnet.kusastro.kyoro-u.ac.jp/vsnet/DNe/egcnc.html (EG Cnc)
We have been undertaking on photometric campaigns on several super-
outbursting dwarf novae and peculiar variable stars. News and call for
observations on these objects will be issued on our regular weekly
"News from VSNET" bulletins. Those who immediately need information
should make an access to the VSNET website, and click on VSNET campaign
list.
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VSNET (Variable Star Network) is an international variable star observing
network, covering various areas of novae, supernovae, cataclysmic variables
(CVs), X-ray transients, and other classical eruptive, pulsating, and
eclipsing variables. VSNET is one of invited contributing organizations
to the SkyPub AstroAlert system.
VSNET Home Page: http://vsnet.kusastro.kyoto-u.ac.jp/vsnet/
CCD observations of such targets are a relatively easy task for a 20-40cm
telescope; simply take as many CCD frames (with exposure times 10-30 sec)
as possible, spanning several hours per night. The only requirements are
the weather and your patience! If you need more help on the observing
technique, please feel free to ask on the vsnet-campaign list.
We would sincerely appreciate volunteers who would join the VSNET
Collaboration team to study the wonders of these exotic variable stars.
To join the VSNET campaign collaborative list, send an e-mail to
vsnet-adm@kusastro.kyoto-u.ac.jp (VSNET administrator)
with a line "SUBSCRIBE vsnet-campaign." or your comment to join the
collaboration team.
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vsnet-adm@kusastro.kyoto-u.ac.jp
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