2019ApJ...881...77Z -
Astrophys. J., 881, 77-77 (2019/August-2)
Non-LTE analyses of high-resolution H-band spectra. III. Neutral and singly ionized calcium.
ZHOU Z.-M., PAN K., SHI J.-R., ZHANG J.-B. and LIU C.
Abstract (from CDS):
A calcium atomic model is updated using collisional rates from new quantum-mechanical computations. We investigated the reliability of the model atom and the non-local thermodynamic equilibrium (NLTE or non-LTE) effects on the formation of Ca I lines in both optical and H bands. NLTE and local thermodynamical equilibrium calcium abundances of 13 sample stars are derived from high-resolution and high signal-to-noise ratio optical spectra and the Apache Point Observatory Galactic Evolution Experiment (APOGEE) data. The results suggest that the updated calcium atomic model is appropriate for studying the formation of H-band calcium lines because our NLTE analyses not only reduce the line-to-line spread of derived abundances, but also lead to consistent optical-line-based and H-band-line-based abundances with a difference of -0.009 ± 0.035 dex and a calcium ionization balance between Ca I and Ca II. In the stellar fundamental parameter space that our sample stars cover, NLTE corrections for H-band Ca I lines are small, within 0.03 dex. Even in the extreme cases of the APOGEE data, the NLTE corrections on selected H-band Ca I lines are within 0.1 dex.
Abstract Copyright:
© 2019. The American Astronomical Society. All rights reserved.
Journal keyword(s):
line: formation - stars: abundances - stars: atmospheres
Simbad objects:
16
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