Photometric and Spectroscopic Properties of Novae in the Large Magellanic Cloud

TL;DR

This study reviews the photometric and spectroscopic properties of 43 novae in the Large Magellanic Cloud, revealing faster decline rates and a higher fraction of He/N and Fe IIb classes compared to other galaxies, linked to stellar population differences.

Contribution

It provides the first comprehensive analysis of LMC novae, highlighting differences in nova properties related to stellar population and white dwarf mass compared to M31 and the Milky Way.

Findings

LMC novae decline faster than those in the Milky Way and M31.

Higher fraction of He/N and Fe IIb novae in the LMC.

Younger stellar population in the LMC leads to higher white dwarf masses.

Abstract

The photometric and spectroscopic properties of the 43 known LMC nova candidates are summarized and reviewed. Of these, photometric data sufficient to establish decline rates are available for 29 novae, while spectroscopic data sufficient to establish the spectroscopic classes are available for 18 systems. Half of the 18 novae belong to the Fe II class, with the remaining nine belonging to either the He/N or the Fe IIb classes. As seen in previous nova studies of M31 and M33, the He/N and Fe IIb novae have on average faster photometric developments than do their Fe II counterparts. Overall, the available photometry confirms earlier studies, and shows conclusively that LMC novae have faster rates of decline than do novae in the Galaxy and M31. It appears that the increased fraction of faster, He/N and Fe IIb novae observed in the LMC compared with M31 is almost certainly the result of differences in the underlying stellar population between the two galaxies. We propose that the younger population seen in the LMC compared with M31's bulge (where most of the novae are found) produces progenitor binaries with higher average white dwarf masses. The higher mean white dwarf mass not only produces a larger fraction of fast, He/N novae compared with M31, but also results in a relatively large recurrent nova population.