The Rate and Spatial Distribution of Novae in M101 (NGC 5457)

TL;DR

This study measures the nova rate in galaxy M101 using multi-epoch H-alpha imaging, finding a rate consistent with previous estimates and showing that nova distribution follows the galaxy's light profile.

Contribution

First comprehensive multi-epoch H-alpha survey of M101 to determine nova rate and spatial distribution, improving accuracy and confirming correlation with galaxy light.

Findings

Nova rate of approximately 11.7 per year in M101.

Nova distribution closely follows the galaxy's background light.

Results align with previous estimates by Shafter et al.

Abstract

A new multi-epoch H-alpha imaging study of M101 (NGC 5457) has been carried out as part of a larger campaign to study the rate and stellar population of extragalactic novae. The survey yielded a total of 13 nova detections from 10 epochs of M101 observations spanning a three year period. After correcting for the temporal coverage and survey completeness, a global nova rate of 11.7^{+1.9}_{-1.5} per year is found. This value corresponds to a luminosity-specific nova rate of 1.23\pm0.27 novae per year per 10^{10} L_{\sun,K} when the K luminosity is derived from the B-K color, or 1.94\pm0.42 novae per year per 10^{10} L_{\sun,K} when the K magnitude from the Two Micron All Sky Survey is used. These values are consistent with previous estimates by Shafter et al. that were based on more limited data. The spatial distribution of the combined nova sample from the present survey and from the earlier Shafter et al. survey shows that the specific frequency of novae closely follows the integrated background light of the galaxy.