2010AJ....140.1119S -
Astron. J., 140, 1119-1127 (2010/October-0)
Light-element abundance variations at low metallicity: the globular cluster NGC 5466.
SHETRONE M., MARTELL S.L., WILKERSON R., ADAMS J., SIEGEL M.H., SMITH G.H. and BOND H.E.
Abstract (from CDS):
We present low-resolution (R ≃850) spectra for 67 asymptotic giant branch (AGB), horizontal branch, and red giant branch (RGB) stars in the low-metallicity globular cluster NGC 5466, taken with the VIRUS-P integral-field spectrograph at the 2.7 m Harlan J. Smith telescope at McDonald Observatory. Sixty-six stars are confirmed, and one rejected, as cluster members based on radial velocity, which we measure to an accuracy of 16 km/s via template-matching techniques. CN and CH band strengths have been measured for 29 RGB and AGB stars in NGC 5466, and the band-strength indices measured from VIRUS-P data show close agreement with those measured from Keck/LRIS spectra previously taken for five of our target stars. We also determine carbon abundances from comparisons with synthetic spectra. The RGB stars in our data set cover a range in absolute V magnitude from +2 to -3, which permits us to study the rate of carbon depletion on the giant branch as well as the point of its onset. The data show a clear decline in carbon abundance with rising luminosity above the luminosity function "bump" on the giant branch, and also a subdued range in CN band strength, suggesting ongoing internal mixing in individual stars but minor or no primordial star-to-star variation in light-element abundances.
Abstract Copyright:
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Journal keyword(s):
globular clusters: general - globular clusters: individual: NGC 5466 - stars: abundances
VizieR on-line data:
<Available at CDS (J/AJ/140/1119): table1.dat>
Nomenclature:
Table 1: [SMW2010] NNNN N=67 among (Nos 690-3387).
Simbad objects:
76
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