STScI Preprint #1210

Stellar Populations and Variable Stars in the Core of the Globular Cluster M5

Based on observations with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by AURA, Inc., under NASA contract NAS5-26555.

We report the discovery of a variable blue straggler in the core of the globular cluster M5, based on a 12-hour long series of images obtained with the Planetary Camera aboard the Hubble Space Telescope. In addition, we present the light curves of 28 previously unknown or poorly studied large-amplitude variable stars (all but one are RR Lyrae) in the cluster core. A(V, U-I) color-magnitude diagram shows 24 blue stragglers within 2 core radii of the cluster center. The blue straggler population is significantly more centrally concentrated than the horizontal branch and red giant stars.

Status:

Appeared in: The Astronomical Journal, 115:725-733, 1998

Affiliations:

¹) Département de Physique, Observatoire du Mont Mégantic, Université Laval Ste-Foy, QC, G1K 7P4, Canada

²) Space Telescope Science Institute 3700 San Martin Drive Baltimore, MD 21218 USA