New Variable Stars in CMa Globular Cluster Candidates

TL;DR

This study identifies new variable stars in the globular clusters M79 and NGC 1851, providing insights into their stellar populations and potential extragalactic origins.

Contribution

It reports the discovery of new RR Lyrae stars and other variables in two globular clusters linked to the Canis Major overdensity, using image subtraction techniques.

Findings

6 new RR Lyrae in M79

At least 4 new variables in NGC 1851

Average RR Lyrae period suggests Oosterhoff II classification

Abstract

We present the preliminary results of an image-subtraction analysis of the Galactic globular cluster M79 (NGC 1904), as well as a new investigation of the variable star population in NGC 1851. Both M79 and NGC 1851 have been previously associated with the Canis Major overdensity, which has been suggested to have an extragalactic origin. We found 6 new RR Lyrae in M79, and also recovered 3 previously known RR Lyrae. The average period of the 5 ab-type RR Lyrae is 0.68 ~ d, corresponding to an Oosterhoff II classification -- which is unusual, though not unprecedented, for systems of extragalactic origin. We also report on the discovery of at least 4 previously unknown variables in NGC 1851.