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[vsnet-campaign-news 55] AstroAlert: WR 106: Another Discovery of Remarkable Optical Variability
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Amateur Discovery of the Second Remarkable Optical Variability
of a Dusty Wolf-Rayet star, WR 106
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The second-ever discovery is again made by an amateur astronomer!
Katsumi Haseda (Aichi, Japan; the discoverer of Nova Sct 2000 = V463 Sct,
is now renowned for his totally unexpected discovery of recurrent, large
variation of WR 104, the "pinwheel star", which was reported in AstroAlert
on the 2001 April 22 issue. He reports the discovery of a large-amplitude
new variable star (HadV84). The star is again identified with an infrared-
luminous WR-type star, WR 106. Both in spectrum, in strong infrared excess,
and in other properties, the new variable star WR 106 = HadV84 is a quite
similar object to WR 104. The present discovery of a fading with a depth
more than two magnitudes suggests that the similar mechanism is taking
place in WR 106, as in WR 104, suggestion of a new class of variable stars
among Wolf-Rayet stars. Further studies on these objects are keenly
in progress, and we await for your participation to VSNET in this exciting
research!
For those who have not read the April 22 issue, we cite the key reference
again: WR 104 is surrounded by a nebula, see also Tuthill et al. 1999, Nature
398, 487: "A dusty pinwheel nebula around the massive star WR 104".
(other on-line information can be read at several internet site, e.g.
http://vsnet.isi.ssl.berkeley.edu/wr104.html)
WR 106 = HadV84 = NSV10152 is located at 18h 04m 43.65s, -21o 09' 30.5"
(J2000.0). The star normally shines at V=11.9, but suddenly falls below
13th magnitude, as experienced in R CrB-type variable stars. The object
is reported bright now (11.7 mag on April 22), but may lose its light
at any time. Continuous monitoring for future events and quick announcement
will be particular important for astronomers who are trying to solve the
mystery of these peculiar Wolf-Rayet stars using huge and space telescopes.
We have been undertaking on photometric campaigns on several super-
outbursting dwarf novae and peculiar variable stars like WR104. 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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