AAVSO: V2362 Cyg: A curious nova

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!