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On the centre-to-limb variation and latitude dependence of the asymmetry and wavelength shift of the solar line λ 5576

✍ Scribed by P. N. Brandt; E. H. Schröter

Publisher
Springer
Year
1982
Tongue
English
Weight
899 KB
Volume
79
Category
Article
ISSN
0038-0938

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✦ Synopsis

Low noise photoelectric measurements of the line profile of the g = 0 Fe line 2 5576.097 combined with determinations of the wavelength shift of its centre calibrated by use of an 12 absorption tube are reported. Measurements taken at various limb distances (1.0 < cos ~ < 0.2) and along 4 different diameters of the Sun are used to investigate the behaviour of the line asymmetry (C-shape) and wavelength shift of the line centre as functions of cos 0 and of latitude and to search for possible pole-equator differences.

An accuracy of approx. 0.8 mA r.m.s, is achieved for the determination of the centre of the solar line relative to the iodine lines and of 0.3 mA to 1 mA r.m.s, for the relative variations of the C-shape. The analysis shows a significant difference between the limb-effect curves along polar and equatorial diameters for cos ~ < 0.4 and changes of the C-shape for 0.9 > cos ~ > 0.6 with a rather strong indication of a latitude dependence of the C-shape. This latitude dependence may account for the so-called 'ears' observed by Howard et al. (1980) who used the well-known Doppler compensator method which integrates the line asymmetry from the line wings to the core. * Mitteilungen aus dem Kiepenheuer-Institut Nr. 207.

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