V2362 Cyg: A Curious Nova
By Matthew Templeton
V2362 Cyg was discovered by
Hideo Nishimura on April 2, 2006,
and verified by Richard Miles on April 4, 2006 at magnitude V ~ 8.5. It was
subsequently classified as a nova, and given its current name; since its
discovery, it has put on quite a show, and astronomers worldwide have been
following it with keen interest. Right now is a prime time to observe this
fascinating star, because of some emerging curious behavior.
Like all classical novae, V2362 Cyg apparently came from nowhere to reach a
very bright maximum. Danny Steeghs et al. found the progenitor star in the IPHAS Project survey data
around r ~ 20.3, giving the nova a very large amplitude of at least 12
magnitudes. The first hint of curiosity was the decline -- V2362 Cyg
appeared to be a fast nova, with a rapid decline over a span of about 20 days.
But the more curiously, V2362 Cyg entered a smooth rebrightening phase. It
didn't return to its peak magnitude of V ~ 8, but it did rebrighten to 10th
magnitude or so, which is very significant -- it's still nearly ten magnitudes
above its likely quiescent level!
Vitaly Goranskij et al. have suggested that this star could be an analog
of the peculiar Nova Aquilae 1999 (V1493 Aql), which also exhibited a rapid
decline followed by a rebrightening several weeks later. Although the
timescales are somewhat different (several weeks for V1493 Aql, versus several
months for V2362 Cyg), the light curves appear to be very similar. What would
cause this behavior? No one is sure yet. Could it be a secondary
thermonuclear outburst? A dwarf nova-like outburst? A curious change in
nova shell morphology? More observations are definitely needed!
AAVSO Director Arne Henden
has been working hard along with several other
astronomers to better understand this star. Multicolor photometry taken by
Arne Henden with the Sonoita Research Observatory and spectroscopy taken by Silverio et al. at Asiago show several curious,
evolving spectroscopic and photometric features that are still being
investigated.
 |
| V-band observations by A. Henden taken with the Sonoita Research Observatory telescope, initiated after the nova had begun its fast
decline. The nova rebrightened to 10th magnitude, but is now in decline. |
As David Boyd pointed out in a recent
post to the AAVSO discussion group, the rebrightening of V2362 Cygnus appears
to be at an end.
If this object is an analog of V1493 Aquilae (N Aql 2000) as Vitaly Goranskij
and co-authors suggest, then V2362 Cyg should now be entering a period of
rapid decline. Observations by the AAVSO community
are therefore urgently requested through the end of the Cygnus observing
season (and beyond, when it re-emerges next year); those of you for whom
Cygnus is circumpolar are uniquely placed to provide important observations
in the weeks and months ahead, and we encourage you especially to contribute.
Both visual and CCD observers have done fantastic work in recording this
strange event, and we hope your great work will continue!