SDO/AIA Observations of Sustained Coronal Condensation and Mass Drainage in Prominences as Return Flows of the Chromosphere-Corona Mass Cycle
Abstract
It has recently been proposed that prominences are manifestations of a magneto-thermal convection process that involves ever-present dynamic descents of cool material threads and upflows of hot bubbles (Berger et al. 2011 Nature). On global scales, prominences may play an important role as the return flows of the chromosphere-corona mass cycle, in which hot mass is originally transported upward through spicules. A critical step in this cycle is the condensation of million-degree coronal plasma into T<10,000 K prominence material by radiative cooling instability. However, direct observation of coronal condensation has been difficult in the past, a situation recently changed with the launch of the Hinode/SOT and SDO/AIA. We present here the first example observed with SDO/AIA, in which hours of gradual cooling through multiple EUV channels (from 2 MK to 80,000 K) in large-scale loops leads to eventual condensation at magnetic dips, forming a moderate-size prominence of 10^14 gram. The prominence mass is not static but maintained by a continual supply through condensation at a high rate of 10^10 gram/s against a comparable drainage through numerous vertical threads at less than free-fall speeds. Most of the total condensation of 10^15 gram, comparable to a CME mass and an order of magnitude more than the instantaneous mass of the prominence itself, is drained in merely one day. These new observations show that a macroscopically quiescent prominence is microscopically dynamic, involving the passage of a significant mass that bears important implications for the chromosphere-corona mass cycle. This interpretation is further supported by the recent theoretical development on spontaneous formation of current sheets and cool condensations (Low, Berger, Casini, & Liu, this meeting).
- Publication:
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SDO-4: Dynamics and Energetics of the Coupled Solar Atmosphere. The Synergy Between State-of-the-Art Observations and Numerical Simulations
- Pub Date:
- March 2012
- Bibcode:
- 2012decs.confE..90L
- Keywords:
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- SDO;
- SDO-4;
- SDO 4;
- SDO Workshop;
- SDO-4/IRIS/Hinode Workshop;
- Solar Dynamic Observatory