dc.contributor.author | Simon, Joshua D. | |
dc.contributor.author | Ji, Alexander Pung | |
dc.contributor.author | Frebel, Anna L. | |
dc.contributor.author | Chiti, Anirudh | |
dc.date.accessioned | 2017-04-24T18:50:17Z | |
dc.date.available | 2017-04-24T18:50:17Z | |
dc.date.issued | 2016-10 | |
dc.identifier.issn | 1538-4357 | |
dc.identifier.uri | http://hdl.handle.net/1721.1/108380 | |
dc.description.abstract | We present chemical abundances derived from high-resolution Magellan/Magellan Inamori Kyocera Echelle spectra of the nine brightest known red giant members of the ultra-faint dwarf galaxy Reticulum II (Ret II). These stars span the full metallicity range of Ret II (−3.5 < [Fe/H] < −2). Seven of the nine stars have extremely high levels of r-process material ([Eu/Fe] ~ 1.7), in contrast to the extremely low neutron-capture element abundances found in every other ultra-faint dwarf galaxy studied to date. The other two stars are the most metal-poor stars in the system ([Fe/H] < −3), and they have neutron-capture element abundance limits similar to those in other ultra-faint dwarf galaxies. We confirm that the relative abundances of Sr, Y, and Zr in these stars are similar to those found in r-process halo stars, but they are ~0.5 dex lower than the solar r-process pattern. If the universal r-process pattern extends to those elements, the stars in Ret II display the least contaminated known r-process pattern. The abundances of lighter elements up to the iron peak are otherwise similar to abundances of stars in the halo and in other ultra-faint dwarf galaxies. However, the scatter in abundance ratios is large enough to suggest that inhomogeneous metal mixing is required to explain the chemical evolution of this galaxy. The presence of low amounts of neutron-capture elements in other ultra-faint dwarf galaxies may imply the existence of additional r-process sites besides the source of r-process elements in Ret II. Galaxies like Ret II may be the original birth sites of r-process enhanced stars now found in the halo. | en_US |
dc.description.sponsorship | National Science Foundation (U.S.) (Grant PHY-1430152) | en_US |
dc.description.sponsorship | National Science Foundation (U.S.) (CAREER Grant AST-1255160) | en_US |
dc.language.iso | en_US | |
dc.publisher | IOP Publishing | en_US |
dc.relation.isversionof | http://dx.doi.org/10.3847/0004-637x/830/2/93 | en_US |
dc.rights | Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use. | en_US |
dc.source | American Astronomical Society | en_US |
dc.title | COMPLETE ELEMENT ABUNDANCES OF NINE STARS IN THE r-PROCESS GALAXY RETICULUM II | en_US |
dc.type | Article | en_US |
dc.identifier.citation | Ji, Alexander P. et al. “COMPLETE ELEMENT ABUNDANCES OF NINE STARS IN THE R -PROCESS GALAXY RETICULUM II.” The Astrophysical Journal 830.2 (2016): 93. © 2016 The American Astronomical Society | en_US |
dc.contributor.department | Massachusetts Institute of Technology. Department of Physics | en_US |
dc.contributor.department | MIT Kavli Institute for Astrophysics and Space Research | en_US |
dc.contributor.mitauthor | Ji, Alexander Pung | |
dc.contributor.mitauthor | Frebel, Anna L. | |
dc.contributor.mitauthor | Chiti, Anirudh | |
dc.relation.journal | Astrophysical Journal | en_US |
dc.eprint.version | Final published version | en_US |
dc.type.uri | http://purl.org/eprint/type/JournalArticle | en_US |
eprint.status | http://purl.org/eprint/status/PeerReviewed | en_US |
dspace.orderedauthors | Ji, Alexander P.; Frebel, Anna; Simon, Joshua D.; Chiti, Anirudh | en_US |
dspace.embargo.terms | N | en_US |
dc.identifier.orcid | https://orcid.org/0000-0002-4863-8842 | |
dc.identifier.orcid | https://orcid.org/0000-0002-2139-7145 | |
dc.identifier.orcid | https://orcid.org/0000-0002-7155-679X | |
mit.license | PUBLISHER_POLICY | en_US |
mit.metadata.status | Complete | |