Derivation of physical parameters of chromospheric structures assuming a constant and a varying source function

Author： Tsiropoula G. Madi C. Schmieder B.

ISSN： 0038-0938

Source： Solar Physics, Vol.187, Iss.1, 1999-06, pp. : 11-22

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Abstract

H profiles of a rosette region consisting of several bright and dark mottles were obtained with the Multichannel Subtractive Double Pass (MSDP) spectrograph mounted on the 50 cm `Tourelle' refractor of the Pic du Midi Observatory. These profiles have been analysed in terms of the classical cloud model which assumes a constant source function and holds only for optically thin structures. A new technique is also described which enables the determination of various physical parameters of chromospheric features taking into account the variation of the source function with the optical depth. This method can be applied, in contrast to the classical cloud model, to all lines whether optically thin or optically thick and gives a good fit to the entire profile from the core to the wings. A comparison of the results given by the two different methods is also performed.