dc.contributor.author Maderak, Ryan M. dc.contributor.author Deliyannis, Constantine P. dc.contributor.author Anthony-Twarog, Barbara dc.contributor.author Twarog, Bruce A. dc.contributor.author Cummings, Jeffery D. dc.contributor.author King, Jeremy R. dc.contributor.author Steiman-Cameron, Thomas Y. dc.date.accessioned 2016-11-15T20:01:52Z dc.date.available 2016-11-15T20:01:52Z dc.date.issued 2015-03-26 dc.identifier.citation Maderak, R. M., Deliyannis, C. P., Anthony-Twarog, B. J., Twarog, B. A., Cummings, J. D., King, J. R., & Steiman-Cameron, T. Y. (2015). WIYN OPEN CLUSTER STUDY. LXIII. ABUNDANCES IN THE SUPER-METAL-RICH OPEN CLUSTER NGC 6253 FROM HYDRA SPECTROSCOPY OF THE 7774 Å OXYGEN TRIPLET REGION. The Astronomical Journal, 149(4), 141. doi:10.1088/0004-6256/149/4/141 en_US dc.identifier.uri http://hdl.handle.net/1808/21966 dc.description.abstract We present a spectroscopic abundance analysis of the old, super-metal-rich open cluster NGC 6253, with emphasis on its O abundance. High-dispersion, 7774 Å O i triplet region spectra of 47 stars were obtained using Hydra II on the CTIO Blanco 4 m. Radial velocity analysis confirms 39 stars consistent with single star membership, primarily at the turnoff. Thirty-six of these are included in our abundance analysis. Our differential analysis relative to the Sun yields primarily scaled-solar values, with weighted cluster averages of [O/H] = +0.440 ± 0.020, [Fe/H] = +0.445 ± 0.014, [Al/H] = +0.487 ± 0.020, [Si/H] = +0.504 ± 0.018, and [Ni/H] = +0.702 ± 0.018 (where the errors are ${{\sigma }_{\mu }}$). We discuss possible origins for the three known super-metal-rich clusters based upon their abundance patterns, Galactic locations, and space motions. The abundance patterns of NGC 6253 are very similar to those of NGC 6791 and NGC 6583. With the possible exception of oxygen, the abundances of these clusters are all close to scaled-solar, and they are similar to patterns seen in metal-rich disk dwarfs and giants. However, they also seem to differ from those of metal-rich bulge stars. We demonstrate that NGC 6253 is unusually oxygen rich (in [O/H]) for its 3.3 Gyr age. While we find [O/Fe] to be scaled-solar for NGC 6253, the more recently reported values for NGC 6791 show a large variation, from values close to scaled-solar down to values at least a factor of two below scaled-solar. We discuss the possibility that the scaled-solar [O/Fe] abundances of NGC 6253 and NGC 6791 might reflect a flattening of the Galactic [O/Fe] versus [Fe/H] relationship. This possibility may be consistent with disk star abundance data, which show an apparent "floor" at [O/Fe] $\sim -0.1$ for [Fe/H] $\gt \;0$, and with chemical evolution model results, which may predict such a flattening due to a decrease in supernova Fe yields at super-solar-metallicities. Orbit solutions for NGC 6791 allow that it may have formed in the inner disk and was then kicked out, but the origins of the other two much younger clusters remain mysterious. We re-evaluate the age of NGC 6583 in view of the evidence that the cluster is super-metal-rich, and confirm a probable age less than 1 Gyr (best range: 500–900 Myr). We also argue that it is unlikely the cluster is more than 3 kpc away (best range: 2–3 kpc) if the apparent turnoff, main sequence, and giants are all cluster members. en_US dc.publisher American Astronomical Society en_US dc.rights © 2015. The American Astronomical Society. All rights reserved. en_US dc.title WIYN Open Cluster Study. LXIII. Abundance in the Super-Metal-Rich Open Cluster NGC 6253 from Hydra Sprectroscopy of the 7774 Å Oxygen Triplet Region en_US dc.type Article en_US kusw.kuauthor Twarog, Bruce A. kusw.kudepartment Physics and Astronomy en_US dc.identifier.doi 10.1088/0004-6256/149/4/141 en_US kusw.oaversion Scholarly/refereed, publisher version en_US kusw.oapolicy This item meets KU Open Access policy criteria. en_US dc.rights.accessrights openAccess
﻿

### This item appears in the following Collection(s)

785-864-8983
KU Libraries
1425 Jayhawk Blvd
Lawrence, KS 66045
785-864-8983

KU Libraries
1425 Jayhawk Blvd
Lawrence, KS 66045