American Association of Variable Star Observers (AAVSO)
Thu, 05/06/2021 - 21:34

I can see in the AAVSO light curve generator that nova V1405 CAS is brightening from the outburst occurred on March 18th. Over the last two weeks it has increased in brightness and it has reached about mag. 7. Any idea of this behaviour?

Vereniging Voor Sterrenkunde, Werkgroep Veranderlijke Sterren (Belgium) (VVS)
V1405 Cas

It is not unusual for slow novae.
They can have a pre-maximum plateau, after which they brighten 1-2 magnitudes.
During the declining phase they still can exhibit a number of brightenings.
Examples are HR Del (Nova Del 1967), V1819 Cyg (Nova Cyg 1986), V723 Cas (Nova Cas 1995) among others.

Bundesdeutsche Arbeitsgemeinschaft fur Veranderliche Sterne e.V.(Germany) (BAV)
V1405 Cas - change in Nova type

As you probably heard/seen, the nova had another strong maximum at aorund 5.5, approx. 2m below first maximum. In addition, the spectra show now typical Fe II lines, no strong He I lines as during first outburst. Lines have strong P Cygni shape, deeper absorption vs. emission. Spectra can be seen on the ARAS database.