AAS 207th Meeting, 8-12 January 2006
Session 69 Stellar Evolution
Poster, Tuesday, 9:20am-6:30pm, January 10, 2006, Exhibit Hall

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[69.17] The Blue Straggler Population of the Globular Cluster M5

S. R. Warren, E. L. Sandquist (SDSU), M. Bolte (UCO/Lick Observatory, UCSC)

We obtained a global blue straggler star population of the galactic globular cluster M5 using multi-wavelength high resolution photometric data from the Hubble Space Telescope and the Canada France Hawaii 3.5 m telescope along with wide-field photometric data from the Cerro Tololo Interamerican Observatory 4 m telescope. Selection criteria for blue stragglers is important when comparing to other studies and special care is necessary when selecting blue stragglers using multiple wavelengths due to color shifts with each star. We compared our blue straggler star sample to three other studies (Ferraro et al. 1997a; Ferraro et al. 2003; Piotto et al. 2004) to gauge the importance of the sample. Using a ``bright'' blue straggler star sample introduced by Ferraro et al. (1997a) we found a bimodal radial distribution consistent with studies from other clusters using similar techniques. When the radial distributions for different clusters are scaled using the core radius, there is good agreement from cluster to cluster. With this we could then overlie the radial distributions of M5 and M3 to better analyze the trend lines. Ferraro et al. (2003) compared their results for M3 to five other clusters with which we compared to M5. The frequency of blue stragglers in M5 is lower than all but one of the clusters examined. We have also identified seven blue stragglers that were previously misidentified as HB stars by Sanquist et al. (2004). These bright stragglers are most likely the result of stellar collisions involving binary stars.

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