Sensitivity of Selected Ba II, Fe I, Fe II, and Cr I Spectral Lines to Velocity in Quiet Solar Atmosphere
Abstract
We examine the sensitivity of selected Ba II, Fe I, Fe II, and Cr I spectral lines to changes of the line-of-sight velocity by sharpness of their line profiles and response functions to line-of-sight velocity evaluated by the 1-D model of the quiet solar atmosphere in the LTE approximation. The set of selected lines includes the Ba II 4554 Å line, generally considered to be an excellent Doppler mapper. Our findings confirm earlier results showing that the sensitivity increases not only with wavelength, as anticipated from the Doppler relation, but mainly with the sharpness of line profiles given by the ratio of their depths and widths. The line Fe I 5247 Å is the most sensitive in our set, whereas the Fe I and Fe II infrared lines show very low sensitivity because of their large thermal widths. The line Ba II 4554 Å shows only moderate sensitivity due to its large width, given by a broad hyperfine structure and isotopic split. For the first time we identify a very promising and so far unknown Doppler mapper of the solar photosphere and low chromosphere, which is the line Ba II 6497 Å. Its sensitivity is comparable with the sensitivity of Fe I 5247 Å and clearly surpasses the sensitivity of Ba II 4554 Å. The line Ba II 6497 Å offers many advantages, making it a highly recommendable choice for future studies of line-of-sight velocities in the photosphere and low chromosphere.
- Publication:
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Solar Physics
- Pub Date:
- October 2010
- DOI:
- 10.1007/s11207-010-9622-4
- Bibcode:
- 2010SoPh..266..261K
- Keywords:
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- Spectral line;
- intensity and diagnostics;
- theory