Interpretation of the East-West Asymmetry of the Initial Appearance of Sunspots
Abstract
The East-West asymmetry in the initial appearance of s'mspots is explained, assuming that sunspots begin to form at a level deeper than optical depth unity and move towards the surface of the s'm, by the variation of the photospheric opacity with height combined with the variation of the heliocentric angle as the observation moves from the centre to the limb. This contribution to the asymmetry is the same order of magnitude as the contribution from the classical "foreshortening effect". A conical model of a sunspot is used to include the contribution of these two effects. A comparison of the theory with the observed East-West asymmetry gives a mean ascentional velocity of the sunspots of 3 m/s. This comparison gives further evidence that the evolution of some sunspots is interrupted.
- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- December 1970
- Bibcode:
- 1970A&A.....9..301R