Hubble Space Telescope Observations of the Post-- Core-Collapse Globular Cluster NGC 6752: A Search for Cataclysmic Variables
Bailyn, Charles D.; Cool, Adrienne M.; Grindlay, Jonathan E.; Rubenstein, Eric P.; Cohn, Haldan; Lugger, Phyllis; Slavin, Shawn D.
Abstract
We report the results of HST WFPC2 observations of the core of NGC 6752. We identify two candidate cataclysmic variables (CVs) from their strong narrowband H alpha emission, periodic variability, and, in one case, a UV excess. We interpret the variability of these stars as being double-peaked, ellipsoidal light curves, in which case the orbital periods are 5.1 and 3.7 hr. The CV candidates fall at the edge of the error circle of one of the known X-ray sources in the cluster.