Atmospheric Composition Of Weak G Band Stars: CNO And Li Abundances

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dc.contributor.utaustinauthorAdamczak, Jensen_US
dc.contributor.utaustinauthorLambert, David L.en_US
dc.creatorAdamczak, Jensen_US
dc.creatorLambert, David L.en_US
dc.date.accessioned2016-04-28T22:21:49Z
dc.date.available2016-04-28T22:21:49Z
dc.date.issued2013-03en
dc.description.abstractWe determined the chemical composition of a large sample of weak G band stars-a rare class of G and K giants of intermediate mass with unusual abundances of C, N, and Li. We have observed 24 weak G band stars with the 2.7 m Harlan J. Smith Telescope at the McDonald Observatory and derived spectroscopic abundances for C, N, O, and Li, as well as for selected elements from Na-Eu. The results show that the atmospheres of weak G band stars are highly contaminated with CN-cycle products. The C underabundance is about a factor of 20 larger than for normal giants and the C-12/C-13 ratio approaches the CN-cycle equilibrium value. In addition to the striking CN-cycle signature the strong N overabundance may indicate the presence of partially ON-cycled material in the atmospheres of the weak G band stars. The exact mechanism responsible for the transport of the elements to the surface has yet to be identified but could be induced by rapid rotation of the main sequence progenitors of the stars. The unusually high Li abundances in some of the stars are an indicator for Li production by the Cameron-Fowler mechanism. A quantitative prediction of a weak G band star's Li abundance is complicated by the strong temperature sensitivity of the mechanism and its participants. In addition to the unusual abundances of CN-cycle elements and Li, we find an overabundance of Na that is in accordance with the NeNa chain running in parallel with the CN cycle. Apart from these peculiarities, the element abundances in a weak G band star's atmosphere are consistent with those of normal giants.en_US
dc.description.departmentAstronomyen_US
dc.description.sponsorshipRobert A. Welch Foundation F-634en_US
dc.identifierdoi:10.15781/T20R79
dc.identifier.Filename2013_03_gband.pdfen_US
dc.identifier.citationAdamczak, Jens, and David L. Lambert. "Atmospheric composition of weak G band stars: CNO and Li abundances." The Astrophysical Journal, Vol. 765, No. 2 (Mar., 2013): 155.en_US
dc.identifier.doi10.1088/0004-637x/765/2/155en_US
dc.identifier.issn0004-637Xen_US
dc.identifier.urihttp://hdl.handle.net/2152/35198
dc.language.isoEnglishen_US
dc.relation.ispartofen_US
dc.relation.ispartofserialAstrophysical 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.rights.restrictionOpenen_US
dc.subjectstars: abundancesen_US
dc.subjectstars: atmospheresen_US
dc.subjectstars: chemically peculiaren_US
dc.subjecteffective temperature scaleen_US
dc.subjectgiant starsen_US
dc.subjectk-giantsen_US
dc.subjectchemical-compositionen_US
dc.subjectdissociation-energyen_US
dc.subjectoxygen abundancesen_US
dc.subjectradial-velocitiesen_US
dc.subjectsolar granulationen_US
dc.subjectlocal regionen_US
dc.subjectlithiumen_US
dc.subjectastronomy & astrophysicsen_US
dc.titleAtmospheric Composition Of Weak G Band Stars: CNO And Li Abundancesen_US
dc.typeArticleen_US

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