Empirical Investigation on the Impact of Hydrogen Collisions for the Formation of CI 1.07 mu~m Lines Based on the Solar Center-to-Limb Variation

Abstract

With an aim of examining the validity of non-LTE line-formation calculations for the strong C I lines of multiplet 1 at 1.068-1.069 mu~m, especially in terms of the treatment of collisions with neutral hydrogen (H I) atoms, we computed theoretical equivalent widths (W_lambda) of these lines corresponding to specific intensities of different angles (mu = cos(theta)) on the solar disk under various conditions, which were then compared with the empirical W_lambda vs. mu relations obtained from our spectroscopic observations using the Domeless Solar Telescope at Hida Observatory. It turned out that our observational data are almost consistent with the theoretical simulations done with the H I collision rates computed with the classical formula, which suggests that the necessity of its significant revision (e.g., considerable reduction) is unlikely.

27 pages, 13 figures, accepted for publication in Pub. Astron. Soc. Japan (Vol. 66, No. 2)

References in corpus (2)

• A grid of MARCS model atmospheres for late-type stars I. Methods and general properties
• Carbon Abundances of Metal-Poor Star Determined from the C I 1.068-1.069 micron Lines

Cited by in corpus (3)

• Does the radial-tangential macroturbulence model adequately describe the spectral line broadening of solar-type stars?
• Solar Center--Limb Variation of the Strengths of Spectral Lines: Classification and Interpretation of Observed Trends
• Towards Spectroscopically Detecting the Global Latitudinal Temperature Variation on the Solar Surface