Light-Element Abundance Variations At Low Metallicity: The Globular Cluster NGC 5466

dc.contributor.utaustinauthorAdams, Joshuaen_US
dc.creatorShetrone, Matthewen_US
dc.creatorMartell, Sarah L.en_US
dc.creatorWilkerson, Rachelen_US
dc.creatorAdams, Joshuaen_US
dc.creatorSiegel, Michael H.en_US
dc.creatorSmith, Graeme H.en_US
dc.creatorBond, Howard E.en_US
dc.description.abstractWe present low-resolution (R similar or equal to 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(-1) 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.en_US
dc.description.departmentMcDonald Observatoryen_US
dc.description.sponsorshipW.M. Keck Foundationen_US
dc.description.sponsorshipCynthia and George Mitchell Foundationen_US
dc.description.sponsorshipNational Science Foundation (NSF) AST-0649128, AST-0406988en_US
dc.identifier.citationShetrone, Matthew, Sarah L. Martell, Rachel Wilkerson, Joshua Adams, Michael H. Siegel, Graeme H. Smith, and Howard E. Bond. >Light-element Abundance Variations at Low Metallicity: The Globular Cluster NGC 5466.> The Astronomical Journal, Vol, 140, No. 4 (Oct., 2010): 1119.en_US
dc.relation.ispartofserialAstronomical Journalen_US
dc.rightsAdministrative deposit of works to Texas ScholarWorks: This works author(s) is or was a University faculty member, student or staff member; this article is already available through open access or the publisher allows a PDF version of the article to be freely posted online. The library makes the deposit as a matter of fair use (for scholarly, educational, and research purposes), and to preserve the work and further secure public access to the works of the University.en_US
dc.subjectglobular clusters: generalen_US
dc.subjectglobular clusters: individual (ngc 5466)en_US
dc.subjectstars: abundancesen_US
dc.subjectred giant branchen_US
dc.subjectubvi photometric systemen_US
dc.subjecthalo field giantsen_US
dc.subjectbright giantsen_US
dc.subjectstellar photometryen_US
dc.subjectcarbon abundanceen_US
dc.subjectstandard starsen_US
dc.subjectastronomy & astrophysicsen_US
dc.titleLight-Element Abundance Variations At Low Metallicity: The Globular Cluster NGC 5466en_US

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