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dc.contributor.authorJohnson, C. I.
dc.contributor.authorCaldwell, Nelson
dc.contributor.authorRich, R. Michael
dc.contributor.authorMateo, Mario
dc.contributor.authorBailey, III, John I.
dc.contributor.authorClarkson, William I.
dc.contributor.authorOlszewski, Edward W.
dc.contributor.authorWalker, Matthew G.
dc.date.accessioned2017-04-24T19:54:17Z
dc.date.available2017-04-24T19:54:17Z
dc.date.issued2017-02-17
dc.identifier.citationA Chemical Composition Survey of the Iron-complex Globular Cluster NGC 6273 (M19) 2017, 836 (2):168 The Astrophysical Journalen
dc.identifier.issn1538-4357
dc.identifier.doi10.3847/1538-4357/836/2/168
dc.identifier.urihttp://hdl.handle.net/10150/623231
dc.description.abstractRecent observations have shown that a growing number of the most massive Galactic globular clusters contain multiple populations of stars with different [Fe/H] and neutron-capture element abundances. NGC 6273 has only recently been recognized as a member of this "iron-complex" cluster class, and we provide here a chemical and kinematic analysis of > 300 red giant branch and asymptotic giant branch member stars using high-resolution spectra obtained with the Magellan-M2FS and VLT-FLAMES instruments. Multiple lines of evidence indicate that NGC 6273 possesses an intrinsic metallicity spread that ranges from about [Fe/H] = -2 to -1 dex, and may include at least three populations with different [Fe/H] values. The three populations identified here contain separate first (Na/Al-poor) and second (Na/Al-rich) generation stars, but a Mg-Al anti-correlation may only be present in stars with [Fe/H] greater than or similar to -1.65. The strong correlation between [La/Eu] and [Fe/H] suggests that the sprocess must have dominated the heavy element enrichment at higher metallicities. A small group of stars with low [alpha/Fe] is identified and may have been accreted from a former surrounding field star population. The cluster's large abundance variations are coupled with a complex, extended, and multimodal blue horizontal branch (HB). The HB morphology and chemical abundances suggest that NGC 6273 may have an origin that is similar to omega Cen and M54.
dc.description.sponsorshipNational Aeronautics and Space Administration; National Science Foundation; Clay Fellowship; National Science Foundation [AST-0923160, AST-1313045, AST-1412999, AST-1413755, AST-1313006]; NASA through Space Telescope Science Institute [GO-14197]en
dc.language.isoenen
dc.publisherIOP PUBLISHING LTDen
dc.relation.urlhttp://stacks.iop.org/0004-637X/836/i=2/a=168?key=crossref.2c2dfc6f75072d75ef72725cc17b59dfen
dc.rights© 2017. The American Astronomical Society. All rights reserved.en
dc.rights.urihttp://rightsstatements.org/vocab/InC/1.0/
dc.subjectglobular clustersen
dc.subjectgeneral - globular clustersen
dc.subjectindividual ( NGC 6273, M19) - starsen
dc.subjectabundances Supporting materialen
dc.subjectmachine-readable tablesen
dc.titleA Chemical Composition Survey of the Iron-complex Globular Cluster NGC 6273 (M19)en
dc.typeArticleen
dc.contributor.departmentUniv Arizona, Steward Observen
dc.identifier.journalThe Astrophysical Journalen
dc.description.collectioninformationThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at repository@u.library.arizona.edu.en
dc.eprint.versionFinal published versionen
refterms.dateFOA2018-09-11T18:52:52Z
html.description.abstractRecent observations have shown that a growing number of the most massive Galactic globular clusters contain multiple populations of stars with different [Fe/H] and neutron-capture element abundances. NGC 6273 has only recently been recognized as a member of this "iron-complex" cluster class, and we provide here a chemical and kinematic analysis of > 300 red giant branch and asymptotic giant branch member stars using high-resolution spectra obtained with the Magellan-M2FS and VLT-FLAMES instruments. Multiple lines of evidence indicate that NGC 6273 possesses an intrinsic metallicity spread that ranges from about [Fe/H] = -2 to -1 dex, and may include at least three populations with different [Fe/H] values. The three populations identified here contain separate first (Na/Al-poor) and second (Na/Al-rich) generation stars, but a Mg-Al anti-correlation may only be present in stars with [Fe/H] greater than or similar to -1.65. The strong correlation between [La/Eu] and [Fe/H] suggests that the sprocess must have dominated the heavy element enrichment at higher metallicities. A small group of stars with low [alpha/Fe] is identified and may have been accreted from a former surrounding field star population. The cluster's large abundance variations are coupled with a complex, extended, and multimodal blue horizontal branch (HB). The HB morphology and chemical abundances suggest that NGC 6273 may have an origin that is similar to omega Cen and M54.


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