Formation of the Profiles of Absorption Lines in the Inhomogeneous Medium

Abstract

The shapes of weak fraunhofer lines, including their asymmetry, are explained by the influence of acoustic waves and granular motions. The following pattern of granula is adopted: the ascending (granular) and descending (intergranular) velocities V₁ and V₂ as well as the relevant temperatures T₁ and T₂ are maximum (minimum) at the center of granula (intergranula) and decrease (increase) sinusoidally outwards. There is also tangential outflow of the matter from the center of granula with the velocity V₃ = const. and temperature T₃ equal to the temperature of the photospheric model T₀. The areas occupied by ascending, descending, and tangential motions are S₁, S₂, S₃ respectively.

The inhomogeneities caused by granulation are perturbed by the acoustic waves with the velocity amplitude V₀ = 0.4 km/s and with the period T = 300 sec. The formula for the absorption line coefficient was derived, and the center-to-limb profiles of 11 weak fraunhofer lines were calculated. The comparison of calculated and observed line profiles have resulted in determining “best fit” values of V₁, V₂, V₃, S₁, S₂, S₃ and ΔT = T₁ - T₂. Tangential motions occupy the larger part of the solar surfaces S₃ = 0.7, V₃ ≈ 2.7 km/s, V ≈ 1.0 km/s, ΔT ranges between 270° - 400°.