Nucleosynthesis And The Inhomogeneous Chemical Evolution Of The Carina Dwarf Galaxy

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dc.contributor.utaustinauthorShetrone, Matthew D.en_US
dc.creatorVenn, Kim A.en_US
dc.creatorShetrone, Matthew D.en_US
dc.creatorIrwin, Mike J.en_US
dc.creatorHill, Vanessaen_US
dc.creatorJablonka, Pascaleen_US
dc.creatorTolstoy, Elineen_US
dc.creatorLemasle, Bertranden_US
dc.creatorDivell, Mikeen_US
dc.creatorStarkenburg, Elseen_US
dc.creatorLetarte, Brunoen_US
dc.creatorBaldner, Charlesen_US
dc.creatorBattaglia, Giuseppinaen_US
dc.creatorHelmi, Aminaen_US
dc.creatorKaufer, Andreasen_US
dc.creatorPrimas, Francescaen_US
dc.date.accessioned2016-04-28T19:34:27Z
dc.date.available2016-04-28T19:34:27Z
dc.date.issued2012-06en
dc.description.abstractThe detailed abundances of 23 chemical elements in nine bright red giant branch stars in the Carina dwarf spheroidal galaxy are presented based on high-resolution spectra gathered at the Very Large Telescope (VLT) and Magellan telescopes. A spherical model atmospheres analysis is applied using standard methods (local thermodynamic equilibrium and plane-parallel radiative transfer) to spectra ranging from 380 to 680 nm. Stellar parameters are found to be consistent between photometric and spectroscopic analyses, both at moderate and high resolution. The stars in this analysis range in metallicity from -2.9 < [Fe/H] < -1.3, and adopting the ages determined by Lemasle et al., we are able to examine the chemical evolution of Carina's old and intermediate-aged populations. One of the main results from this work is the evidence for inhomogeneous mixing in Carina and therefore for a poor statistical sampling of the supernova contributions when forming stars; a large dispersion in [Mg/Fe] indicates poor mixing in the old population, an offset in the [alpha/Fe] ratios between the old and intermediate-aged populations (when examined with previously published results) suggests that the second star formation event occurred in alpha-enriched gas, and one star, Car-612, seems to have formed in a pocket enhanced in SN Ia/II products. This latter star provides the first direct link between the formation of stars with enhanced SN Ia/II ratios in dwarf galaxies to those found in the outer Galactic halo (Ivans et al.). Another important result is the potential evidence for SNII driven winds. We show that the very metal-poor stars in Carina have not been enhanced in asymptotic giant branch or SN Ia products, and therefore their very low ratios of [Sr/Ba] suggests the loss of contributions from the early SNe II. Low ratios of [Na/Fe], [Mn/Fe], and [Cr/Fe] in two of these stars support this scenario, with additional evidence from the low [Zn/Fe] upper limit for one star. It is interesting that the chemistry of the metal-poor stars in Carina is not similar to those in the Galaxy, most of the other dwarf spheroidal galaxies, or the ultra faint dwarfs, and suggests that Carina may be at the critical mass where some chemical enrichments are lost through SN II driven winds.en_US
dc.description.departmentMcDonald Observatoryen_US
dc.description.sponsorshipNSERCen_US
dc.description.sponsorshipNSF AST 99-84073en_US
dc.identifierdoi:10.15781/T2MN7V
dc.identifier.Filename2012_06_carinadwarf.pdfen_US
dc.identifier.citationVenn, Kim A., Matthew D. Shetrone, Mike J. Irwin, Vanessa Hill, Pascale Jablonka, Eline Tolstoy, Bertrand Lemasle et al. "Nucleosynthesis and the Inhomogeneous Chemical Evolution of the Carina Dwarf Galaxy." The Astrophysical Journal, Vol. 751, No. 2 (Jun., 2012): 102.en_US
dc.identifier.doi10.1088/0004-637x/751/2/102en_US
dc.identifier.issn0004-637Xen_US
dc.identifier.urihttp://hdl.handle.net/2152/34783
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.subjectgalaxies: abundancesen_US
dc.subjectgalaxies: dwarfen_US
dc.subjectgalaxies: evolutionen_US
dc.subjectgalaxies:en_US
dc.subjectindividual (carina dwarf galaxy)en_US
dc.subjectlocal groupen_US
dc.subjectmetal-poor starsen_US
dc.subjectmultielement abundance measurementsen_US
dc.subjecthigh-resolutionen_US
dc.subjectspectroscopyen_US
dc.subjectred giant branchen_US
dc.subjecteffective temperature scaleen_US
dc.subjectneutron-capture elementsen_US
dc.subjectglobular-cluster m68en_US
dc.subjectiron peak elementsen_US
dc.subjectspheroidal galaxyen_US
dc.subjectmilky-wayen_US
dc.subjectastronomy & astrophysicsen_US
dc.titleNucleosynthesis And The Inhomogeneous Chemical Evolution Of The Carina Dwarf Galaxyen_US
dc.typeArticleen_US

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