TY - JOUR
T1 - Sodium and oxygen abundances in the open cluster NGC 6791 from apogee H-band spectroscopy
AU - Cunha, Katia
AU - Smith, Verne V.
AU - Johnson, Jennifer A.
AU - Bergemann, Maria
AU - Mészáros, Szabolcs
AU - Shetrone, Matthew D.
AU - Souto, Diogo
AU - Prieto, Carlos Allende
AU - Schiavon, Ricardo P.
AU - Frinchaboy, Peter
AU - Zasowski, Gail
AU - Bizyaev, Dmitry
AU - Holtzman, Jon
AU - García Pérez, Ana E.
AU - Majewski, Steven R.
AU - Nidever, David
AU - Beers, Timothy
AU - Carrera, Ricardo
AU - Geisler, Doug
AU - Gunn, James
AU - Hearty, Fred
AU - Ivans, Inese
AU - Martell, Sarah
AU - Pinsonneault, Marc
AU - Schneider, Donald P.
AU - Sobeck, Jennifer
AU - Stello, Dennis
AU - Stassun, Keivan G.
AU - Skrutskie, Michael
AU - Wilson, John C.
N1 - Publisher Copyright:
© 2015. The American Astronomical Society. All rights reserved.
PY - 2015/1/10
Y1 - 2015/1/10
N2 - The open cluster NGC 6791 is among the oldest, most massive, and metal-rich open clusters in the Galaxy. High-resolution H-band spectra from the Apache Point Observatory Galactic Evolution Experiment (APOGEE) of 11 red giants in NGC 6791 are analyzed for their chemical abundances of iron, oxygen, and sodium. The abundances of these three elements are found to be homogeneous (with abundance dispersions at the level of ∼0.05-0.07 dex) in these cluster red giants, which span much of the red-giant branch (Teff ∼ 3500-4600 K), and include two red clump giants. From the infrared spectra, this cluster is confirmed to be among the most metal-rich clusters in the Galaxy (〈[Fe/H]〉 = 0.34 ± 0.06) and is found to have a roughly solar value of [O/Fe] and slightly enhanced [Na/Fe]. Our non-LTE calculations for the studied Na I lines in the APOGEE spectral region (16373.86 Å and 16388.85 Å) indicate only small departures from LTE (≤0.04 dex) for the parameter range and metallicity of the studied stars. The previously reported double population of cluster members with different Na abundances is not found among the studied sample.
AB - The open cluster NGC 6791 is among the oldest, most massive, and metal-rich open clusters in the Galaxy. High-resolution H-band spectra from the Apache Point Observatory Galactic Evolution Experiment (APOGEE) of 11 red giants in NGC 6791 are analyzed for their chemical abundances of iron, oxygen, and sodium. The abundances of these three elements are found to be homogeneous (with abundance dispersions at the level of ∼0.05-0.07 dex) in these cluster red giants, which span much of the red-giant branch (Teff ∼ 3500-4600 K), and include two red clump giants. From the infrared spectra, this cluster is confirmed to be among the most metal-rich clusters in the Galaxy (〈[Fe/H]〉 = 0.34 ± 0.06) and is found to have a roughly solar value of [O/Fe] and slightly enhanced [Na/Fe]. Our non-LTE calculations for the studied Na I lines in the APOGEE spectral region (16373.86 Å and 16388.85 Å) indicate only small departures from LTE (≤0.04 dex) for the parameter range and metallicity of the studied stars. The previously reported double population of cluster members with different Na abundances is not found among the studied sample.
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U2 - 10.1088/2041-8205/798/2/L41
DO - 10.1088/2041-8205/798/2/L41
M3 - Article
AN - SCOPUS:84920784152
SN - 2041-8205
VL - 798
JO - Astrophysical Journal Letters
JF - Astrophysical Journal Letters
IS - 2
M1 - L41
ER -