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Chemical Abundances of Main-sequence, Turnoff, Subgiant, and Red Giant Stars from APOGEE Spectra. I. Signatures of Diffusion in the Open Cluster M67

Souto, Diogo; Cunha, Katia; Smith, Verne V.; Prieto, C. Allende; García-Hernández, D. A.; Pinsonneault, Marc; Holzer, Parker; Frinchaboy, Peter; Holtzman, Jon and Johnson, J. A., et al. (2018) In Astrophysical Journal 857(1).
Abstract

Detailed chemical abundance distributions for 14 elements are derived for eight high-probability stellar members of the solar metallicity old open cluster M67 with an age of ∼4 Gyr. The eight stars consist of four pairs, with each pair occupying a distinct phase of stellar evolution: two G dwarfs, two turnoff stars, two G subgiants, and two red clump (RC) K giants. The abundance analysis uses near-IR high-resolution spectra (λ1.5-1.7 μm) from the Apache Point Observatory Galactic Evolution Experiment survey and derives abundances for C, N, O, Na, Mg, Al, Si, K, Ca, Ti, V, Cr, Mn, and Fe. Our derived stellar parameters and metallicity for 2M08510076+1153115 suggest that this star is a solar twin, exhibiting abundance differences relative... (More)

Detailed chemical abundance distributions for 14 elements are derived for eight high-probability stellar members of the solar metallicity old open cluster M67 with an age of ∼4 Gyr. The eight stars consist of four pairs, with each pair occupying a distinct phase of stellar evolution: two G dwarfs, two turnoff stars, two G subgiants, and two red clump (RC) K giants. The abundance analysis uses near-IR high-resolution spectra (λ1.5-1.7 μm) from the Apache Point Observatory Galactic Evolution Experiment survey and derives abundances for C, N, O, Na, Mg, Al, Si, K, Ca, Ti, V, Cr, Mn, and Fe. Our derived stellar parameters and metallicity for 2M08510076+1153115 suggest that this star is a solar twin, exhibiting abundance differences relative to the Sun of ≤0.04 dex for all elements. Chemical homogeneity is found within each class of stars (∼0.02 dex), while significant abundance variations (∼0.05-0.20 dex) are found across the different evolutionary phases; the turnoff stars typically have the lowest abundances, while the RCs tend to have the largest. Non-LTE corrections to the LTE-derived abundances are unlikely to explain the differences. A detailed comparison of the derived Fe, Mg, Si, and Ca abundances with recently published surface abundances from stellar models that include chemical diffusion provides a good match between the observed and predicted abundances as a function of stellar mass. Such agreement would indicate the detection of chemical diffusion processes in the stellar members of M67.

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diffusion, infrared: stars, open clusters and associations: general, stars: abundances
in
Astrophysical Journal
volume
857
issue
1
publisher
American Astronomical Society
external identifiers
  • scopus:85045553903
ISSN
0004-637X
DOI
10.3847/1538-4357/aab612
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English
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yes
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fa3e08d2-eb49-4ef9-9355-761b554edc88
date added to LUP
2018-04-27 11:30:50
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2019-10-08 03:28:03
@article{fa3e08d2-eb49-4ef9-9355-761b554edc88,
  abstract     = {<p>Detailed chemical abundance distributions for 14 elements are derived for eight high-probability stellar members of the solar metallicity old open cluster M67 with an age of ∼4 Gyr. The eight stars consist of four pairs, with each pair occupying a distinct phase of stellar evolution: two G dwarfs, two turnoff stars, two G subgiants, and two red clump (RC) K giants. The abundance analysis uses near-IR high-resolution spectra (λ1.5-1.7 μm) from the Apache Point Observatory Galactic Evolution Experiment survey and derives abundances for C, N, O, Na, Mg, Al, Si, K, Ca, Ti, V, Cr, Mn, and Fe. Our derived stellar parameters and metallicity for 2M08510076+1153115 suggest that this star is a solar twin, exhibiting abundance differences relative to the Sun of ≤0.04 dex for all elements. Chemical homogeneity is found within each class of stars (∼0.02 dex), while significant abundance variations (∼0.05-0.20 dex) are found across the different evolutionary phases; the turnoff stars typically have the lowest abundances, while the RCs tend to have the largest. Non-LTE corrections to the LTE-derived abundances are unlikely to explain the differences. A detailed comparison of the derived Fe, Mg, Si, and Ca abundances with recently published surface abundances from stellar models that include chemical diffusion provides a good match between the observed and predicted abundances as a function of stellar mass. Such agreement would indicate the detection of chemical diffusion processes in the stellar members of M67.</p>},
  articleno    = {14},
  author       = {Souto, Diogo and Cunha, Katia and Smith, Verne V. and Prieto, C. Allende and García-Hernández, D. A. and Pinsonneault, Marc and Holzer, Parker and Frinchaboy, Peter and Holtzman, Jon and Johnson, J. A. and Jönsson, Henrik and Majewski, Steven R. and Shetrone, Matthew and Sobeck, Jennifer and Stringfellow, Guy and Teske, Johanna and Zamora, Olga and Zasowski, Gail and Carrera, Ricardo and Stassun, Keivan and Fernandez-Trincado, J. G. and Villanova, Sandro and Minniti, Dante and Santana, Felipe},
  issn         = {0004-637X},
  keyword      = {diffusion,infrared: stars,open clusters and associations: general,stars: abundances},
  language     = {eng},
  month        = {04},
  number       = {1},
  publisher    = {American Astronomical Society},
  series       = {Astrophysical Journal},
  title        = {Chemical Abundances of Main-sequence, Turnoff, Subgiant, and Red Giant Stars from APOGEE Spectra. I. Signatures of Diffusion in the Open Cluster M67},
  url          = {http://dx.doi.org/10.3847/1538-4357/aab612},
  volume       = {857},
  year         = {2018},
}