| Title: |
Chemical Abundances of Main-sequence, Turnoff, Subgiant, and Red Giant Stars from APOGEE Spectra. II. Atomic Diffusion in M67 Stars. |
| Authors: |
Diogo Souto1 diogodusouto@gmail.com, C. Allende Prieto2,3, Katia Cunha1,4, Marc Pinsonneault5, Verne V. Smith6, R. Garcia-Dias2,3, Jo Bovy7,8, D. A. García-Hernández2,3, Jon Holtzman9, J. A. Johnson5, Henrik Jönsson10, Steve R. Majewski11, Matthew Shetrone12, Jennifer Sobeck11, Olga Zamora2,3, Kaike Pan13, Christian Nitschelm14 |
| Source: |
Astrophysical Journal. 3/20/2019, Vol. 874 Issue 1, p1-1. 1p. |
| Subject Terms: |
*RED giants, *GLOBULAR clusters, *LOCAL thermodynamic equilibrium, *MAIN sequence (Astronomy), *DIFFUSION, *GALACTIC evolution, *HR diagrams |
| Abstract: |
Chemical abundances for 15 elements (C, N, O, Na, Mg, Al, Si, K, Ca, Ti, V, Cr, Mn, Fe, and Ni) are presented for 83 stellar members of the 4 Gyr old solar-metallicity open cluster M67. The sample contains stars spanning a wide range of evolutionary phases, from G dwarfs to red clump stars. The abundances were derived from near-IR (λ1.5–1.7 μm) high-resolution spectra (R = 22,500) from the SDSS-IV/Apache Point Observatory Galactic Evolution Experiment (APOGEE) survey. A 1D local thermodynamic equilibrium abundance analysis was carried out using the APOGEE synthetic spectral libraries, via χ2 minimization of the synthetic and observed spectra with the qASPCAP code. We found significant abundance differences (∼0.05–0.30 dex) between the M67 member stars as a function of the stellar mass (or position on the Hertzsprung–Russell diagram), where the abundance patterns exhibit a general depletion (in [X/H]) in stars at the main-sequence turnoff. The amount of the depletion is different for different elements. We find that atomic diffusion models provide, in general, good agreement with the abundance trends for most chemical species, supporting recent studies indicating that measurable atomic diffusion operates in M67 stars. [ABSTRACT FROM AUTHOR] |
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