SIMBAD references

begin{tex}Binary stars should be present in relatively large numbers in globular clusters (GCs). While individual binary systems have been previously observed, until now, no large population had been detected in a dense GC. As part of this thesis, we developed a new technique to determine the fraction of main-sequence stars which are binaries. We analyzed the redward spread of the main-sequence ridge-line of the post-core-collapse GC NGC∼6752. These data, obtained with post-refurbishment HST data, indicate that in the inner core-radius, the 3-σlower and upper limits on the binary fraction are 15% and 38%, respectively. The region outside the core has a 3-σupper limit on the binary fraction of 16%, and is consistent with no binaries. This rapid change in binary fraction is clear evidence of mass segregation operating within the inner 3 core-radii. We also find that the binary fraction increases at fainter magnitudes; mass segregation would also account for such behavior. We discuss the likely effects on the cluster's luminosity function (LF). In particular, we find that if the contribution of binaries to the LF was not removed, the apparent number of low mass stars would be over-estimated. I also examined the time-series data and discovered that one of the blue stragglers in NGC∼6752 is an SX Phe pulsator. Its pulsation mass is 1-1.2 M_☉, consistent with the mass of the best fit stellar models from the Yale Isochrones, and also consistent with any of the blue straggler formation scenarios. No contact or eclipsing binaries were unambiguously detected. However, many low-amplitude variable candidates were observed at the limit of our ability to detect variability. The putative period of these candidate objects is consistent with these objects being produced via tidal capture events. In a time-series study of NGC∼6397, we found a contact binary. This W∼UMa system probably has a mass greater than that of main sequence turn-off stars implying that when this system coalesces due to angular momentum loss, it will become a blue straggler star. The frequency of W∼UMas in this cluster is not statistically different from that of other GCs where ∼0.1% of the main-sequence stars are contact binaries.