Limb effect of solar absorption lines |
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| Authors: | B N Andersen |
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| Institution: | (1) Institute of Theoretical Astrophysics, University of Oslo, Norway |
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| Abstract: | Low-noise limb-effect observations of the non-magnetic line Fei 557.6 nm are presented. Separate measurements along the solar equator and the meridian have been carried out and have been corrected for scattered light. The limb-effect line shifts at the pole and at the equatorial limb are found to be equal. The detailed shape of the limb effect along the meridian is found to differ significantly from that along the equator. This difference can be explained by the presence of a meridional circulation pattern, with horizontal flows < 50 m–1 from both the equator and poles toward ± 45° latitude. Alternatively the meridian/equator difference may be caused by a combination of latitude dependence of the granular parameters. An increase with latitude of the granular velocity scale height, contrast, or mean sizes could explain the observations. |
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