Friday, January 25, 2013

1301.5864 (Erik D. Reinhart et al.)

The Color-Magnitude Diagram of the Globular Cluster M14    [PDF]

Erik D. Reinhart, Thayne A. McCombs, Andrew N. Darragh, Zheyu J. Liu, Brian W Murphy, Kyle E. Conroy
Using the SARA 0.9 meter telescope at Kitt Peak National Observatory (KPNO) we obtained R images during the summer of 2010 and V images during the summer of 2012 of the globular cluster M14. These images were analyzed using the DAOPHOT/ALLFRAME package of Stetson (1987,1994) to create a preliminary color-magnitude diagram (CMD) of M14. We have positively identified the positions of 64 of the 112 known RR Lyrae stars on the CMD. We find considerable spread in both the magnitudes and color of the RR Lyrae stars indicating a significant amount of differential reddening on relatively small scales. This is also seen in the giant branch which shows up to ~0.15 magnitude spread in V-R color. We also found the median magnitude of the RR Lyrae stars and hence the horizontal branch to be V=17.2.
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