Bibcode
Souto, D.; Cunha, Katia; Smith, Verne V.; Allende Prieto, C.; García-Hernández, D. A.; Pinsonneault, Marc; Holzer, Parker; Frinchaboy, Peter; Holtzman, Jon; Johnson, J. A.; Jönsson, Henrik; Majewski, Steven R.; Shetrone, Matthew; Sobeck, Jennifer; Stringfellow, Guy; Teske, Johanna; Zamora, O.; Zasowski, Gail; Carrera, Ricardo; Stassun, Keivan; Fernandez-Trincado, J. G.; Villanova, Sandro; Minniti, Dante; Santana, Felipe
Bibliographical reference
The Astrophysical Journal, Volume 857, Issue 1, article id. 14, 19 pp. (2018).
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2018
Journal
Citations
58
Refereed citations
55
Description
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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