Wei Liu, Thomas E. Berger, B. C. Low
Imaging solar coronal condensation forming prominences was difficult in the
past, a situation recently changed by Hinode and SDO. We present the first
example observed with SDO/AIA, in which material gradually cools through
multiple EUV channels in a transequatorial loop system that confines an earlier
eruption. Nine hours later, this leads to eventual condensation at the dip of
these loops, forming a moderate-size prominence of ~$10^{14}$ gram, to be
compared to the characteristic $10^{15}$ gram mass of a CME. The prominence
mass is not static but maintained by condensation at a high estimated rate of
$10^{10}$ gram/sec against a comparable, sustained drainage through numerous
vertical downflow threads, such that 96% of the total condensation (~$10^{15}$
gram) is drained in approximately one day. The mass condensation and drainage
rates temporally correlate with the total prominence mass. The downflow
velocity has a narrow Gaussian distribution with a mean of 30 km/s, while the
downward acceleration distribution has an exponential drop with a mean of ~1/6
$g_{Sun}$, indicating a significant canceling of gravity, possibly by the
Lorentz force. Our observations show that a macroscopic quiescent prominence is
microscopically dynamic, involving the passage of a significant mass through
it, maintained by a continual mass supply against a comparable mass drainage,
which bears important implications for CME initiation mechanisms in which mass
unloading is important.
View original:
http://arxiv.org/abs/1201.0811
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