Observations of the birth of a small coronal hole

By using soft X-ray data from the S-054 X-ray spectrographic telescope aboard Skylab, the authors observed temporal changes in the emission structure of the X-ray corona associated with the birth of a small coronal hole. Designated as CH6, this coronal hole was born near the Equator in a time interval less than 91/2 hr. By constructing a light curve for a point near the center of CH6, a sudden 40% decrease in X-ray emission associated with the birth of this coronal hole was observed. On a time scale of hours, the growth of CH6 in area proceeded faster than the average rate predicted by the diffusion of solar fields. The short-term decay of CH6 followed the diffusive rate to within experimental uncertainty. On a time scale of one rotation, the subsequent development of CH6 was not consistent with steady growth at the average rate predicted by diffusion.