M31N 1926-07c: A Recurrent Nova in M31 with a 2.8 Year Recurrence Time

TL;DR

This paper studies the recurrent nova M31N 1926-07c in M31, analyzing recent eruptions to determine its recurrence interval and photometric behavior, revealing it has one of the shortest known recurrence times at approximately 2.78 years.

Contribution

The study provides detailed light curves of recent eruptions and establishes a precise recurrence interval for M31N 1926-07c, highlighting its status as a short-recurrence nova.

Findings

Recurrence interval of 2.78 years with low uncertainty

Similar photometric evolution across recent eruptions

One of the shortest known recurrence times for novae

Abstract

The M31 recurrent nova M31N 1926-07c has had five recorded eruptions. Well-sampled light curves of the two most recent outbursts, in January of 2020 (M31N 2020-01b) and September 2022 (M31N 2022-09a), are presented showing that the photometric evolution of the two events were quite similar, with peak magnitudes of $R=17.2\pm0.1$ and $R=17.1\pm0.1$, and $t_2$ times of $9.7\pm0.9$ and $8.1\pm0.5$ days for the 2020 and 2022 eruptions, respectively. After considering the dates of the four most recent eruptions (where the cycle count is believed to be known), a mean recurrence interval of $\langle P_\mathrm{rec}\rangle=2.78\pm0.03$ years is found, establishing that M31N 1926-07c has one of the shortest recurrence times known.