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Over the last few nights V606 Vul (Nova Vul 2021) has faded from mag 12.5 to 15.5. It has a particularly interesting lightcurve. Can anyone educate a comet observer and explain what is going on?
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Could be the formation of optically thick dust similar to what happened with Nova Cas 2020 (=V1391 Cas).
David
Latest datapoint in AAVSO is 16.9V on Nov 11. That’s a 4.5 mag drop in just 5 days. Pretty quick. V1391 Cas took twice as long to drop by a similar magnitude ~ 10 days.
Gary
The formation of dust is the usual reason for these sudden dips, and that is consistent with the reddening as shown in the recent photometry, but what about the big humps when it was bright? Is that dust related too or is it an actual brightening of the disc? V1405 Cas has these humps too whereas other novae (V1674 Her for instance) don’t.
Novae are such fascinating things!
This recent paper considers the origin of this flaring phenomenon – it’s actually about another nova, but they generalise to all of these slow, dusty systems. However, they state that it’s still an open question -and there may be multiple scenarios in different systems. They favour multiple episodes of mass ejection. They propose that the photosphere expands during a flare – the flares produce shocks which lead to high energy gamma-rays and dust production, others due to instabilities in the accretion disc around the white dwarf created by enhanced accretion stimulated by heating from the secondary star.
The authors of that paper (which include amateurs) make plea for further studies of other novae, so it is good that you and others are following this nova.
Found this paper as well on dust shells that might be of interest.
Sorry. Here is a working link: http://pure.southwales.ac.uk/files/1764788/stw3334.pdf
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