Line-Profile Analysis of KI 7699 in the Sun and in Procyon

Abstract

The profiles of the resonance line of potassium (KI 7698.98) in the flux spectrum of the Sun and Procyon were studied in detail using the multi-parameter fitting method, in order to extract information regarding the fundamental atomic parameters responsible for the formation of this line as well as to diagnose the nature of the velocity fields in their atmospheres. It was concluded from an analysis of the solar KI 7699 profile that neutral-hydrogen collisions are practically negligible compared to electron collisions in the rate equation of statistical equilibrium, and that an empirical correction to the Unsöld's standard (van der Waals effect) damping constant is Δ log C6 ≃ + 1.0 with the most consistent microturbulent velocity of ξ ≃ 0.8 km s−1 . Based upon these results, the atmospheric-velocity parameters of Procyon were determined to be ξ ≃ 1.4 km s−1, ζRT≃ 6.7 km s−1 (the radial-tangential macroturbulence), and ve sin i ≃ 3.3 km s−1 (the projected rotational velocity). The potassium abundances of the Sun and Procyon derived from this resonance line, which are significantly affected by the non-LTE effect amounting to ∼ 0.4 dex (Sun) and ∼ 0.7 dex (Procyon), turned out to be nearly the same and log εK ≃ 5.1. It also appears that the microturbulence tends to decrease with an increase in the atmospheric height of the Sun as well as of Procyon.