The Nova Rate in M94 (NGC 4736)

TL;DR

This study measures the nova rate in galaxy M94 using multi-epoch H-alpha observations, finding a rate slightly lower than similar galaxies, and provides a methodology for estimating nova rates based on luminosity.

Contribution

The paper presents the first nova rate measurement for M94 using a multi-epoch H-alpha survey, correcting for observational completeness and deriving specific nova rates based on luminosity.

Findings

Nova rate in M94 is approximately 5 per year.

Specific nova rate is about 1.4 to 1.5 per 10^10 L_sun,K.

M94's nova rate is slightly lower than other galaxies.

Abstract

A multi-epoch H$\alpha$ survey of the early-type spiral galaxy M94 (NGC 4736) has been completed as part of a program to establish the galaxy's nova rate. A total of four nova candidates were discovered in seven epochs of observation during the period from 2005 to 2007. After making corrections for temporal coverage and spatial completeness, a global nova rate of 5.0$^{+1.8}_{-1.4}$ yr$^{-1}$ was determined. This rate corresponds to a specific-luminosity nova rate of 1.4 $\pm$ 0.5 novae per year per 10$^{10} L_{\odot,K}$ when the $K$ luminosity is determined from the $B-K$ color, or 1.5 $\pm$ 0.4 novae per year per 10$^{10} L_{\odot,K}$ when the $K$ luminosity is derived from the Two Micron All Sky Survey. These values are slightly lower than that of other galaxies with measured nova rates, which typically lie in the range of $2-3$ novae per year per 10$^{10} L_{\odot}$ in the $K$ band.