The very short supersoft X-ray state of the classical nova M31N 2007-11a

TL;DR

This paper reports the discovery and analysis of a classical nova in M31 with an exceptionally short supersoft X-ray phase, indicating a massive white dwarf and providing insights into nova evolution and supernova progenitors.

Contribution

It presents the first detailed optical and X-ray monitoring of M31N 2007-11a, revealing a very short supersoft X-ray state and constraining the white dwarf mass.

Findings

Supersoft X-ray phase lasted 45-58 days

X-ray appearance occurred 6-16 days after outburst

White dwarf mass estimated to be >1 solar mass

Abstract

Short supersoft X-ray source (SSS) states (durations < 100 days) of classical novae (CNe) indicate massive white dwarfs that are candidate progenitors of supernovae type Ia. We carry out a dedicated optical and X-ray monitoring program of CNe in the bulge of M 31. We discovered M31N 2007-11a and determined its optical and X-ray light curve. We used the robotic Super-LOTIS telescope to obtain the optical data and XMM-Newton and Chandra observations to discover an X-ray counterpart to that nova. Nova M31N 2007-11a is a very fast CN, exhibiting a very short SSS state with an appearance time of 6-16 days after outburst and a turn-off time of 45-58 days after outburst. The optical and X-ray light curves of M31N 2007-11a suggest a binary containing a white dwarf with a mass greater than one solar mass.