Profiles of strong lines in K- dwarfs

Abstract

A study of the profiles of strong lines in two stars € Eridani and Gmb 1830 has been done. The following lines were investigated: Hα; D₁ and D₂ lines of Na_I; H- and K-lines of Ca _II; and the infrared triplet lines of Ca _II. Model atmospheres were constructed in the majority of cases investigated, using a scaled solar (T-τ) relation. Line profiles were then constructed. For € Eridani, all the profiles could be explained well with the use of solar composition and with effective temperature, T_e = 5050° K. For Gmb 1830, all the profiles except Hα could be explained well with T_e = 5000° K and hydrogen-to-metal ratio of twenty times the solar value, with sodium depleted more with respect to that of the solar value by a factor of 2. For Hα, the effect of convection is shown to have some effect. In a parallel calculation, it was found that the calculated and the observed profiles for the Sun do not agree if the Bohm-Vitense (T-τ) relation is used.