Paper detail

The H-alpha Light Curves and Spatial Distribution of Novae in M81

We present the results of a preliminary H-alpha survey of M81 for novae conducted over a 5 month interval using the 5' field of view camera (WFCAM) on the Calypso Telescope at Kitt Peak, AZ. We observed M81 nearly every clear night during this interval, covering the entire galaxy, and discovered 12 novae. Our comprehensive time coverage allowed us to produce the most complete set of H-alpha light curves for novae in M81 to date. A raw nova rate for M81 gives 23 yr^-1 which, because of the nature of our survey, is a hard lower limit. An analysis of the completeness in our survey gives a corrected nova rate of 30 yr^-1. This agrees well with the rate of 33 (+13,-8) yr^-1, derived from Monte Carlo simulations using nova light curves and survey frame limits. The spatial distribution of the novae we discovered follows the bulge light much better than the disk or total light according to Kolmogorov - Smirnov tests of their radial distributions. The asymmetry in the distribution of novae across the major axis line of M81 implies a bulge-to-disk nova ratio of > 9 and supports the idea that novae originate primarily in older stellar populations.