BIRTH, LIFE, AND DEATH OF A SOLAR CORONAL PLUME

We analyze a solar polar-coronal-hole (CH) plume over its entire approximate to 40 hr lifetime, using high-resolution Solar Dynamic Observatory Atmospheric Imaging Assembly (AIA) data. We examine (1) the plume's relationship to a bright point (BP) that persists at its base, (2) plume outflows and their possible contribution to the solar wind mass supply, and (3) the physical properties of the plume. We find that the plume started approximate to 2 hr after the BP first appeared and became undetectable approximate to 1 hr after the BP disappeared. We detected radially moving radiance variations from both the plume and from interplume regions, corresponding to apparent outflow speeds ranging over approximate to(30-300) km s(-1) with outflow velocities being higher in the "cooler" AIA 171 angstrom channel than in the "hotter" 193 angstrom and 211 angstrom channels, which is inconsistent with wave motions; therefore, we conclude that the observed radiance variations represent material outflows. If they persist into the heliosphere and plumes cover approximate to 10% of a typical CH area, these flows could account for approximate to 50% of the solar wind mass. From a differential emission measure analysis of the AIA images, we find that the average electron temperature of the plume remained approximately constant over its lifetime, at T-e approximate to 8.5 x 10(5) K. Its density, however, decreased with the age of the plume, being about a factor of three lower when the plume faded compared to when it was born. We conclude that the plume died due to a density reduction rather than to a temperature decrease.