V1405 Cas re-brightenings question

American Association of Variable Star Observers (AAVSO)
Sun, 06/27/2021 - 14:58

Hi everyone,

I've been following the evolution of the nova V1405 Cas and am curious what may be causing it to rebrighten almost cyclically. I believe it's now on its third upswing. I'd be grateful for any help in understanding its behavior.

Thank you very much!

Bob (KRB)


Bundesdeutsche Arbeitsgemeinschaft fur Veranderliche Sterne e.V.(Germany) (BAV)
J class nova ?



I think V1405 Cas matches the J class novae in the classification scheme of Strope, Schaeffer, & Henden (2010). A similar case is V723 Cas (late 1995-1996). There are also O class novae which show regular oscillations but typically below the first maximum. V1391 Cas from last year is a bit like this.

I never saw a good physical explanation for the more or less regular ascillations. Is it due to more than one thermonuclear runaway or just thermal instabilities or anything else? If someone has seen more detailed explanations, I would be happy to learn.