M31N 2017-01e: Discovery of a Previous Eruption in this Enigmatic Recurrent Nova

Abstract

We report the discovery of a previously unknown eruption of the recurrent nova M31N 2017-01e that took place on 11 January 2012. The earlier eruption was detected by Pan-STARRS and occurred 1847 days (5.06 yr) prior to the eruption on 31 January 2017 (M31N 2017-01e). The nova has now been seen to have had a total of four recorded eruptions (M31N 2012-01c, 2017-01e, 2019-09d, and 2022-03d) with a mean time between outbursts of just $929.5\pm 6.8$ days ($2.545\pm 0.019$ yr), the second shortest recurrence time known for any nova. We also show that there is a blue variable source ($⟨V⟩=20.56\pm 0.17$, $B-V\simeq 0.045$), apparently coincident with the position of the nova, that exhibits a 14.3 d periodicity. Possible models of the system are proposed, but none are entirely satisfactory.

11 pages, 3 tables, 1 figure; Accepted for publication in Research Notes of the AAS