The Chemical Imprint Of Silicate Dust On The Most Metal-Poor Stars

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dc.contributor.utaustinauthorBromm, Volkeren_US
dc.creatorAlexander, P.en_US
dc.creatorFrebel, Annaen_US
dc.creatorBromm, Volkeren_US
dc.date.accessioned2016-04-28T19:42:27Z
dc.date.available2016-04-28T19:42:27Z
dc.date.issued2014-02en
dc.description.abstractWe investigate the impact of dust-induced gas fragmentation on the formation of the first low-mass, metal-poor stars (<1 M-circle dot) in the early universe. Previous work has shown the existence of a critical dust-to-gas ratio, below which dust thermal cooling cannot cause gas fragmentation. Assuming that the first dust is silicon-based, we compute critical dust-to-gas ratios and associated critical silicon abundances ([Si/H](crit)). At the density and temperature associated with protostellar disks, we find that a standard Milky Way grain size distribution gives [Si/H](crit) = -4.5 +/- 0.1, while smaller grain sizes created in a supernova reverse shock give [Si/H](crit) = -5.3 +/- 0.1. Other environments are not dense enough to be influenced by dust cooling. We test the silicate dust cooling theory by comparing to silicon abundances observed in the most iron-poor stars ([Fe/H] < -4.0). Several stars have silicon abundances low enough to rule out dust-induced gas fragmentation with a standard grain size distribution. Moreover, two of these stars have such low silicon abundances that even dust with a shocked grain size distribution cannot explain their formation. Adding small amounts of carbon dust does not significantly change these conclusions. Additionally, we find that these stars exhibit either high carbon with low silicon abundances or the reverse. A silicate dust scenario thus suggests that the earliest low-mass star formation in the most metal-poor regime may have proceeded through two distinct cooling pathways: fine-structure line cooling and dust cooling. This naturally explains both the carbon-rich and carbon-normal stars at extremely low [Fe/H].en_US
dc.description.departmentAstronomyen_US
dc.description.sponsorshipNSF AST-1255160, AST-1009928en_US
dc.description.sponsorshipNASA ATFP NNX09-AJ33Gen_US
dc.identifierdoi:10.15781/T2C807
dc.identifier.Filename2014__02_chemicalimprint.pdfen_US
dc.identifier.citationJi, Alexander P., Anna Frebel, and Volker Bromm. "The Chemical Imprint of Silicate Dust on the Most Metal-poor Stars." The Astrophysical Journal, Vol. 782, No. 2 (Feb., 2014): 95.en_US
dc.identifier.doi10.1088/0004-637x/782/2/95en_US
dc.identifier.issn0004-637Xen_US
dc.identifier.urihttp://hdl.handle.net/2152/35141
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.subjectearly universeen_US
dc.subjectstars: abundancesen_US
dc.subjectstars: formationen_US
dc.subjectstars: populationen_US
dc.subjectiien_US
dc.subjectlow-mass starsen_US
dc.subjectplanck mean opacitiesen_US
dc.subjectprimordial gas cloudsen_US
dc.subject1st starsen_US
dc.subjectearly universeen_US
dc.subjectoxygen abundanceen_US
dc.subjectforming cloudsen_US
dc.subjecthigh-redshiften_US
dc.subjectprotostellar feedbacken_US
dc.subjectcritical metallicityen_US
dc.subjectastronomy & astrophysicsen_US
dc.titleThe Chemical Imprint Of Silicate Dust On The Most Metal-Poor Starsen_US
dc.typeArticleen_US

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