Discovery, photometry, and astrometry of 49 classical nova candidates in M 81 galaxy

Abstract

Aims: This paper reports on a search for new classical nova candidates in the M 81 galaxy based on archival, as well as recent, new images.
Methods: We used images from 1999-2007 to search for optical transients in M 81. The positions of the identified classical nova candidates were used to study their spatial distribution. Kolmogorov-Smirnov test (KS) and bottom-to-top (BTR) ratio diagnostic were used to analyze the nova candidate distribution and differentiate between the disk and the bulge populations.
Results: In total, 49 classical nova candidates were discovered. In this study, we present the precise positions and photometry of these objects, plus the photometry of an additional 9 classical nova candidates found by Neill & Shara (2004, AJ, 127, 816). With our large sample, we find a different spatial distribution of classical nova candidates when compared to the results of earlier studies. Also, an extraordinarily bright nova was found and studied in detail.

Partly based on observations obtained at the Gemini Observatory (acquired through the Gemini Science Archive), which is operated by the Association of Universities for Research in Astronomy, Inc., under a cooperative agreement with the NSF on behalf of the Gemini partnership: the National Science Foundation (United States), the Particle Physics and Astronomy Research Council (United Kingdom), the National Research Council (Canada), CONICYT (Chile), the Australian Research Council (Australia), CNPq (Brazil) and CONICET (Argentina).