Prominence and Coronal Structure

Abstract

IN a paper communicated to the Royal Society in December last (Roy. Soc. Proc., A, vol. lxxx., p. 178), an abstract of which appeared in this journal (vol. lxxvii., p. 314, April 2), I directed attention to a peculiar form of prominence which had been photographed with the spectro-heliograph of the Solar Physics Observatory in the “K” light of calcium. This prominence, situated towards the south pole of the sun in the eastern quadrant, about position-angle 137°, was recorded on two separate negatives taken at the times 3h. 14m. p.m. and 3h. 50m. p.m. G.M.T. on July 17, 1907. Although on each photograph images of other prominences were recorded, no particular attention was directed to them, as they did not present any unusual features. It may, however, be incidentally remarked that the most intense prominence recorded on both the photographs, and situated near the south pole in the western quadrant about position-angle 218°, was reproduced in, the paper in Plate iii., Fig. 5. I did not think it necessary for the purpose of that communication to reproduce the whole limb of the sun, but confined myself to the disturbed area in the south-eastern quadrant. The presence of a large prominence in the south-western quadrant has raised questions of identity, so the complete limb is now here reproduced (Fig. 1) to show the relationship between the two prominences and the sun's south pole.