BIRTH, LIFE, AND DEATH OF A SOLAR CORONAL PLUME

We analyze a solar polar-coronal-hole (CH) plume over its entire [asymptotically =]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 outflow...

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Bibliographic Details
Published in:The Astrophysical journal 2014-10, Vol.793 (2), p.1-11
Main Authors: Pucci, Stefano, Poletto, Giannina, Sterling, Alphonse C, Romoli, Marco
Format: Article
Language:English
Subjects:
APPROXIMATIONS
ASTROPHYSICS, COSMOLOGY AND ASTRONOMY
Asymptotic properties
AVAILABILITY
BORON PHOSPHIDES
Channels
COMPARATIVE EVALUATIONS
Coolers
DENSITY
ELECTRON TEMPERATURE
EMISSION
HEAT EXCHANGERS
HELIOSPHERE
LIFETIME
MASS
Outflow
PLUMES
Radiance
REDUCTION
RESOLUTION
SOLAR WIND
SUN
ULTRAVIOLET RADIATION
VELOCITY
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Summary:We analyze a solar polar-coronal-hole (CH) plume over its entire [asymptotically =]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 [asymptotically =]2 hr after the BP first appeared and became undetectable [asymptotically =]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 [asymptotically =](30-300) km s super(-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 [asymptotically =]10% of a typical CH area, these flows could account for 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 sub(e) [asymptotically =] 8.5 x 10 super(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.
ISSN:1538-4357
0004-637X
1538-4357
DOI:10.1088/0004-637X/793/2/86