Applications of Fourier analysis to broadening of stellar line profiles. III. Solar microturbulence and macroturbulence from iron lines.
Abstract
Kitt Peak solar profiles of iron lines obtained at = 0.63 have been utilized to study the solar velocity field. The high quality of these data and the lack of influence of rotation make possible a modeling of the macroturbulent velocity distribution as well as a determination of the micro turbulence. The analysis was performed by matching computed and observed criteria in both the wavelength and the Fourier transform domains. The principal ambiguities in evaluating microturbulence are caused by the uncertainty in the functional form of macroturbulence and in the value of the atomic damping constants. The form of the first sidelobe in the data transfbrms indicates the existence of a low (k + 41 km s1) micro turbulence at intermediate photo spheric regions which increases toward larger depths. Attempts were made to fit profiles with macroturbulences of a wide variety of functional forms. In the wavelength representation the Voigt distribution gives the best overall fit, whereas in the transform domain an exponential function matches the observed sidelobe best. A comparison of all the results (Table 2) shows only a small disparity in bestfit parameters around a mean of 2.0 km 1 A triangular macrovelocity distribution which is similar to that predicted by a radialtangential model is recovered explicitly by deconvolution. However, for practical reasons a good oneparameter fit to it is provided by the exponential function. Because this function is very dissimilar to the rotation function, it should be possible to evaluate macroturbulence and rotation separately in sharplined latetype stars. Subject headings: line profiles  Sun: atmospheric motions  Sun: spectra
 Publication:

The Astrophysical Journal
 Pub Date:
 July 1976
 DOI:
 10.1086/154495
 Bibcode:
 1976ApJ...207..308S
 Keywords:

 Atmospheric Turbulence;
 Fourier Analysis;
 Line Shape;
 Solar Atmosphere;
 Solar Spectra;
 Spectral Line Width;
 Atmospheric Models;
 Fourier Transformation;
 Iron;
 Late Stars;
 Photosphere;
 Stellar Models;
 Astronomy