Classical Novae in Andromeda: Light Curves from the Palomar Transient Factory and GALEX

TL;DR

This study provides detailed optical and UV light curves of 29 novae in M31, revealing their photometric evolution, UV emission characteristics, and nova rates in globular clusters, using high-cadence observations from PTF and GALEX.

Contribution

First detailed optical and UV light curves of M31 novae from high-cadence surveys, including UV detection and nova rate analysis in globular clusters.

Findings

UV emission peaks before optical maxima in some novae.

PT And is confirmed as a recurrent nova in M31.

Nova rate in M31 globular clusters is about one per year.

Abstract

We present optical light curves of twenty-nine novae in M31 during the 2009 and 2010 observing seasons of the Palomar Transient Factory (PTF). The dynamic and rapid cadences in PTF monitoring of M31, from one day to even ten minutes, provide excellent temporal coverage of nova light curves, enabling us to record the photometric evolution of M31 novae in unprecedented detail. We also detect eight of these novae in the near ultraviolet (UV) band with the Galaxy Evolution Explorer (GALEX) satellite. Novae M31N2009-10b and 2010-11a show prominent UV emission peaking a few days prior to their optical maxima, possibly implying aspherical outbursts. Additionally, our blue-shifted spectrum of the recent outburst of PT And (M31N2010-12a) indicates that it is a recurrent nova in M31 and not a dwarf nova in the Milky Way as was previously assumed. Finally, we systematically searched for novae in all confirmed globular clusters of M31 and found only M31N 2010-10f associated with Bol 126. The specific nova rate in the M31 globular cluster system is thus about one per year which is not enhanced relative to the rate outside the globular cluster system.