BC Cassiopeiae: First Detection of IW And-Type Phenomenon Among Post-Eruption Novae

TL;DR

This paper reports the first observation of an IW And-type dwarf nova behavior in the post-eruption nova BC Cassiopeiae, linking high mass-transfer rates and massive white dwarfs to this phenomenon.

Contribution

It is the first to identify IW And-type behavior in a post-eruption nova, suggesting a connection between white dwarf mass, high mass-transfer rates, and this variability.

Findings

BC Cas exhibited IW And-type dwarf nova behavior in 2018.

High white dwarf mass inferred from nova decline rate.

High mass-transfer rate associated with IW And-type phenomenon.

Abstract

IW And-type dwarf novae are recently recognized group of cataclysmic variables which are characterized by a sequence of brightening from a standstill-like phase with damping oscillations often followed by a deep dip. We found that the supposed classical nova BC Cas which erupted in 1929 experienced a state of an IW And-type dwarf nova in 2018, 89 yr after the eruption. This finding suggests that high mass-transfer rate following the nova eruption is associated with the IW And-type phenomenon. The mass of the white dwarf inferred from the decline rate of the nova is considerably higher than the average mass of the white dwarfs in cataclysmic variables and the massive white dwarfs may be responsible for the manifestation of the IW And-type phenomenon.