Program: GN-2019B-Q-221

As the most nearby spiral galaxy with resolved stellar populations, M31 provides unique opportunities for stellar physics, in particular constraining rates of various transient phenomena. Novae eruption are caused by thermal nuclear runaway on the surface of white dwarfs accreting material from their non-degenerate companions and thus are low mass counterparts of SNe Ia. While previous surveys have detected numerous novae in M31 (see e.g. Pietsch et al. 2007), they are limited by the survey cadence and most of the novae detected are relatively slow novae and their light curves are not complete. We are particularly interested in fast novae (fade out within 10 days), because they are 1) composed of most massive white dwarfs hence pose a test to the white dwarf theories, and 2) difficult to chart given the spare observations of previous surveys. In addition, recurrent novae are also of special interests, as they might retain material and gain mass cycle after cycle, and explode as SNe Ia at some point. Here we propose spectroscopic target-of-opportunity (ToO) observations for follow-up of nova candidates in M31 identified from the public alert stream of the Zwicky Transient Facility (ZTF). We have been using the community broker ANTARES to digest the ZTF alerts, and implemented a dedicated M31 alert stream to flag transients within 2x2 degrees of M31. The only missing part of our M31 fast/recurrent novae study is spectroscopic information, which will be delivered by the Gemini/GMOS observations in this proposal.