Formation of granular intensity fluctuations on the Sun

Universitäts-Sternwarte, Geismarlandstraße 11, 37083 Göttingen, Germany

Corresponding author: F. Kneer, kneer@uni-sw.gwdg.de

Received: 24 June 2002
Accepted: 27 August 2002

Abstract

We deal with granular intensity fluctuations in the Sun and how they are caused by temperature fluctuations. We calculate temperature response functions in the solar photosphere. We apply the Diagonal Element Lambda Operator (DELO) method to calculate the response functions for the continuum ( nm–2.5 μ). LTE is assumed throughout. It is demonstrated that, within the framework of the linear approximation, the H^- continuum absorption plays an important rôle for the formation of the fluctuations in continuum images. It counteracts substantially the intensity fluctuations caused by variations of the Planck function. The temperature response functions are used to calculate, for three models of temperature fluctuations, the continuum intensity contrasts and their formation height for the above wavelength range.