Solar limb effect and meridional flow - Results on the Fe I lines at 5569.6 A and 5576.1 A
Abstract
A description is given of an investigation on the center-to-limb variation of the line asymmetry and shift along the polar and equatorial diameters of the sun on two Fe I photospheric lines. The observations, obtained with the Fabry-Perot spectrointerferometer installed at the Donati Solar Tower Telescope in Arcetri, do not show any significant latitudinal dependence of the line asymmetry. Instead, the limb shift curves obtained along the polar diameter systematically differ from those obtained along the equator. This difference, if interpreted as due to a surface mass flow, implies a poleward meridional motion with a maximum of about 50 m/s at 45 deg of latitude in both hemispheres. A detailed analysis of these and previous results suggests that the so called 'meridional motions', found by spectroscopical means, mainly originate from latitudinal effects on the convective line shift, which might also be modulated by the activity cycle. This interpretation does not exclude the fact that small meridional mass flows are present on the sun, like those found from the tracers drifts.
- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- July 1986
- Bibcode:
- 1986A&A...163..219C
- Keywords:
-
- Iron;
- Line Spectra;
- Meridional Flow;
- Solar Limb;
- Solar Rotation;
- Solar Spectra;
- Convection;
- Photosphere;
- Spectrum Analysis;
- Solar Physics