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dc.contributor.authorFrebel, Anna L.
dc.contributor.authorCasey, Andrew R.
dc.contributor.authorJacobson, Heather
dc.contributor.authorYu, QinQin
dc.date.accessioned2014-07-17T18:13:08Z
dc.date.available2014-07-17T18:13:08Z
dc.date.issued2013-05
dc.identifier.issn0004-637X
dc.identifier.issn1538-4357
dc.identifier.urihttp://hdl.handle.net/1721.1/88425
dc.description.abstractIt is well established that stellar effective temperatures determined from photometry and spectroscopy yield systematically different results. We describe a new, simple method to correct spectroscopically derived temperatures ("excitation temperatures") of metal-poor stars based on a literature sample with –3.3 < [Fe/H] < –2.5. Excitation temperatures were determined from Fe I line abundances in high-resolution optical spectra in the wavelength range of ~3700-~7000 Å, although shorter wavelength ranges, up to 4750-6800 Å, can also be employed, and compared with photometric literature temperatures. Our adjustment scheme increases the temperatures up to several hundred degrees for cool red giants, while leaving the near-main-sequence stars mostly unchanged. Hence, it brings the excitation temperatures in good agreement with photometrically derived values. The modified temperature also influences other stellar parameters, as the Fe I-Fe II ionization balance is simultaneously used to determine the surface gravity, while also forcing no abundance trend on the absorption line strengths to obtain the microturbulent velocity. As a result of increasing the temperature, the often too low gravities and too high microturbulent velocities in red giants become higher and lower, respectively. Our adjustment scheme thus continues to build on the advantage of deriving temperatures from spectroscopy alone, independent of reddening, while at the same time producing stellar chemical abundances that are more straightforwardly comparable to studies based on photometrically derived temperatures. Hence, our method may prove beneficial for comparing different studies in the literature as well as the many high-resolution stellar spectroscopic surveys that are or will be carried out in the next few years.en_US
dc.description.sponsorshipAustralian Research Council (Laureate Fellowship 0992131)en_US
dc.description.sponsorshipMassachusetts Institute of Technology. Undergraduate Research Opportunities Programen_US
dc.description.sponsorshipAustralia. Department of Education (Australian Prime Minister’s Endeavour Award Research Fellowship)en_US
dc.language.isoen_US
dc.publisherInstitute of Physics Publishingen_US
dc.relation.isversionofhttp://dx.doi.org/10.1088/0004-637x/769/1/57en_US
dc.rightsCreative Commons Attribution-Noncommercial-Share Alikeen_US
dc.rights.urihttp://creativecommons.org/licenses/by-nc-sa/4.0/en_US
dc.sourcearXiven_US
dc.titleDERIVING STELLAR EFFECTIVE TEMPERATURES OF METAL-POOR STARS WITH THE EXCITATION POTENTIAL METHODen_US
dc.typeArticleen_US
dc.identifier.citationFrebel, Anna, Andrew R. Casey, Heather R. Jacobson, and Qinsi Yu. “DERIVING STELLAR EFFECTIVE TEMPERATURES OF METAL-POOR STARS WITH THE EXCITATION POTENTIAL METHOD.” The Astrophysical Journal 769, no. 1 (May 20, 2013): 57.en_US
dc.contributor.departmentMassachusetts Institute of Technology. Department of Physicsen_US
dc.contributor.departmentMIT Kavli Institute for Astrophysics and Space Researchen_US
dc.contributor.mitauthorFrebel, Anna L.en_US
dc.contributor.mitauthorCasey, Andrew R.en_US
dc.contributor.mitauthorJacobson, Heatheren_US
dc.contributor.mitauthorYu, Qinsien_US
dc.relation.journalAstrophysical Journalen_US
dc.eprint.versionAuthor's final manuscripten_US
dc.type.urihttp://purl.org/eprint/type/JournalArticleen_US
eprint.statushttp://purl.org/eprint/status/PeerRevieweden_US
dspace.orderedauthorsFrebel, Anna; Casey, Andrew R.; Jacobson, Heather R.; Yu, Qinsien_US
dc.identifier.orcidhttps://orcid.org/0000-0001-7727-1640
dc.identifier.orcidhttps://orcid.org/0000-0002-2139-7145
mit.licenseOPEN_ACCESS_POLICYen_US


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