Color maps of X-ray globular clusters

Journal Article · Mon Aug 01 00:00:00 EDT 1988 · Astrophys. J.; (United States)

DOI:https://doi.org/10.1086/166554· OSTI ID:7089240

Bailyn, C D; Grindlay, J E; Cohn, H; Lugger, P M

The results of a search for optical counterparts to X-ray sources in six globular clusters, 47 Tuc, NGC 1851, NGC 6441, NGC 6624, NGC 6712, and M15, are reported. Maps of the U-B color of the central regions of the clusters were prepared. A candidate for the optical counterpart of the source in NGC 6712 was found, along with a blue region near the X-ray source in 47 Tuc. Upper limits on the colors and magnitudes of possible optical counterparts are reported for the other three clusters. The use of color maps to determine color gradients in globular clusters is explored. It is found that, while such gradients do exist and vary from cluster to cluster, they can be explained by crowding effects. Crude limits are placed on the excess populations of blue objects such as CVs, which have been postulated to be concentrated in the centers of dense clusters. 32 references.

• Research Organization: Harvard-Smithsonian Center for Astrophysics, Cambridge, MA (USA); Indiana Univ., Bloomington (USA)
• OSTI ID: 7089240
• Journal Information: Astrophys. J.; (United States), Vol. 331
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
STAR CLUSTERS
X RADIATION
BINARY STARS
COSMIC X-RAY SOURCES
LUMINOSITY
MAPS
PHOTOMETRY
RED GIANT STARS
COSMIC RAY SOURCES
ELECTROMAGNETIC RADIATION
GIANT STARS
IONIZING RADIATIONS
OPTICAL PROPERTIES
PHYSICAL PROPERTIES
RADIATIONS
STARS
640102* - Astrophysics & Cosmology- Stars & Quasi-Stellar
Radio & X-Ray Sources