  The reported positions of 964 suspected nova eruptions in M31 recorded
through the end of calendar year 2013 have been compared in order to identify
recurrent nova candidates. To pass the initial screen and qualify as a
recurrent nova candidate two or more eruptions were required to be coincident
within 0.1', although this criterion was relaxed to 0.15' for novae discovered
on early photographic patrols. A total of 118 eruptions from 51 potential
recurrent nova systems satisfied the screening criterion. To determine what
fraction of these novae are indeed recurrent the original plates and published
images of the relevant eruptions have been carefully compared. This procedure
has resulted in the elimination of 27 of the 51 progenitor candidates (61
eruptions) from further consideration as recurrent novae, with another 8
systems (17 eruptions) deemed unlikely to be recurrent. Of the remaining 16
systems, 12 candidates (32 eruptions) were judged to be recurrent novae, with
an additional 4 systems (8 eruptions) being possibly recurrent. It is estimated
that ~4% of the nova eruptions seen in M31 over the past century are associated
with recurrent novae. A Monte Carlo analysis shows that the discovery
efficiency for recurrent novae may be as low as 10% that for novae in general,
suggesting that as many as one in three nova eruptions observed in M31 arise
from progenitor systems having recurrence times <~100 yr. For plausible system
parameters, it appears unlikely that recurrent novae can provide a significant
channel for the production of Type Ia supernovae.

Solar and Stellar Astrophysics