On the determination of the photospheric velocity distribution from profiles of weak Fraunhofer lines

✍ Scribed by R. J. Rutten; P. Hoyng; C. Jager

• Publisher: Springer
• Year: 1974
• Tongue: English
• Weight: 653 KB
• Volume: 38
• Category: Article
• ISSN: 0038-0938
• DOI: 10.1007/bf00155070

✦ Synopsis

We derive the conditions under which the profile of a weak Fraunhofer line can be described as the convolution of the separate profiles of damping, thermal and non-thermal motions at the average depth of formation of the line. The average velocity distribution along the line of sight, rather than its customary chosen macro-and micro-turbulent components, is then found from the deconvolution of the observed profile with the known other contributions. Reversely, the observed profiles can be compared to predicted profiles on the basis of De Jager's (1974) theoretical turbulence broadening curves.

These two methods are tested on four suitable lines. The results indicate a non-gaussian velocity distribution with arms velocity of about 3 km s -1 and show that the photospheric turbulence is not incompatible with Kolmogoroff's law.