We report the discovery of a probable CH star in the core of the Galactic globular cluster M14 ( = NGC 6402 = C1735-032 ) , identified from an integrated-light spectrum of the cluster obtained with the MOS spectrograph on the Canada-France-Hawaii telescope .
From a high-resolution echelle spectrum of the same star obtained with the Hydra fiber positioner and bench spectrograph on the WIYN telescope , we measure a radial velocity of -53.0 \pm 1.2 km s ^ { -1 } .
Although this velocity is inconsistent with published estimates of the systemic radial velocity of M14 ( e.g. , { \bar { v _ { r } } } \approx - 123 km s ^ { -1 } ) , we use high-precision Hydra velocities for 20 stars in the central 2 \farcm 6 of M14 to calculate improved values for the cluster mean velocity and one-dimensional velocity dispersion : -59.5 \pm 1.9 km s ^ { -1 } and 8.2 \pm 1.4 km s ^ { -1 } , respectively .
Both the star ’ s location near the tip of the red giant branch in the cluster color magnitude diagram and its radial velocity therefore argue for membership in M14 .
Since the intermediate-resolution MOS spectrum shows not only enhanced CH absorption but also strong Swan bands of C _ { 2 } , M14 joins \omega Cen as the only globular clusters known to contain “ classical ” CH stars .
Although evidence for its duplicity must await additional radial velocity measurements , the CH star in M14 is probably , like all field CH stars , a spectroscopic binary with a degenerate ( white dwarf ) secondary .
The candidate and confirmed CH stars in M14 and \omega Cen , and in a number of Galactic dSph galaxies , may then owe their existence to the long timescales for the shrinking and coalescence of hard binaries in low-concentration environments .