The Relative Positions of Sunspots and Flares

This paper describes a study of 11 flaring sunspots, for which on flare days the relative positions of flares andsunspots have been determined from data provided by the Climax and the Mount Wilson Observatories. For eachspot group all data, including the magnetic polarities and field strengths, were projected to the center of the sun'sdisc and combined.The maps show that flaring tends to prefer regions containing both polarities rather than unipolar areas withina spot group. The favored zone may be a spot cluster containing both polarities, as within fly and y groups, or aregion occupied by transient spots of both polarities, as in the following component of some fip and ap groups.Statistical analysis shows that flares preferred these regions more often than would be expected by chance.A supplementary investigation including additional sunspots revealed no correlation between frequency of flaringand internal spot activity such as the breakup or merging or small components.A count of spot umbras covered by flares was made. About 10 percent of the flares show clear or possiblecoverage of some part of a spot umbra. Theflaresobserved here covered the spots only partially or along the edges,a positional relation markedly different from that found by Ellison et al. for cosmic-ray flares where the main bodyof the flare passed directly over the sunspot. U.S. GOVERNMENT PRINTING OFFICE: 1963 O—680448