Observations of Solar Magnitic Fields.

Abstract

The magnetograph at the 150-foot solar tower at Mount Wilson Observatory was used to trace a number of active and quiet regions on the surface of the sun with an angular resolution of about 10 seconds of arc. It was found that magnetic features exist near sunspots with fields exceeding 75 gauss. Changes in the magnetic features, as seen from magnetic contour maps made on different days, were frequent. The flux measured near spots was in most cases sufficient to balance the flux from the spots. There is good evidence for a tilting of the lines of force of the photospheric magnetic field in the direction of a sunspot. Magnetic contour maps show that magnetic features bear a close resemblance to calciumplage regions. In all cases the plages were outlined very nearly by a 10-gauss contour line. Where filaments (prominences) were present in regions removed from plages, in all cases it was found that they occurred in areas where the field was less than 10 gauss. Moreover, the magnetic features on either side of the filaments were always of different polarities. It is suggested that the magnetic field in the solar photosphere and chromosphere is in the form of more or less vertical columns.