The solar atmosphere around active regions

Abstract

Solar observation has been made at the Observatory of the Bangkok Planetarium, and sunspot data taken with the 150 mm-Zeiss-Coude’ refractor at the observatory are reduced. The Wolf’s sunspot number and types of sunspot groups are found. The coordinates of sunspots are calculated and also approximately deduced by the use of solar grids prepared by the Fraunhofer Institute. the development of two nearby sunspot groups from 20 November to 1 December 1967 are studied in the light of Babcock’s theory on the formation of sunspot gromps. Both groups seemed to be produced by a single flux rope of the same turn. Analysis of the data, however, indicates that they did not occur from the same flux rope of the same turn. dark features on H-alpha filtergrams around an isolated spot on 16 August, 1967 are studied. Most of them show horizontal motions of material toward the spot while some of them show loop structures. The long threads which are the darkest features in the filtergrams show downward motion to the solar surface. They are interpreted as prominences. A model of magnetic field configuration around the spot in the chromosphere is presented.