pctr physics and “chewy nougats*”
DESCRIPTION
PCTR Physics and “Chewy Nougats*”. SSL, UC Berkeley. * This nomenclature due either to Greg Slater or Sam Freeland, SXT data pioneers (most likely Greg). What is the prominence-corona transition region (PCTR)?. - PowerPoint PPT PresentationTRANSCRIPT
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PCTR Physics and“Chewy Nougats*”
SSL, UC Berkeley
* This nomenclature due either to Greg Slater or Sam Freeland, SXT data pioneers (most likely Greg)
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ISSI Jan. 14, 2009
What is the prominence-corona transition region (PCTR)?
• Analogous (?) with the horizontally stratified ordinary TR, it separates the cold prominence from the hot corona
• It must be closely aligned with the separatrix between filament fields and cavity fields
• There are several approaches to understanding it: DEM, radio, filaments, hydrodynamic, MHD, each seemingly with its own literature
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ISSI Jan. 14, 2009
Vernazza, Avrett & Loeser 1981
Behind the DEM approach
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ISSI Jan. 14, 2009
Different views of the prominence-corona transition region
Kucera & Landi, 2008
Cirigliano et al. 2004
Antiochos & Klimchuk 1991 Heinzel et al. 2008
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ISSI Jan. 14, 2009
“Chewy Nougat” There is a hot (soft X-ray) brightening around the cold prominence
Hudson et al. 1999
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ISSI Jan. 14, 2009
The original nougat as seen on the disk
Some polar nougats found by Okumura
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ISSI Jan. 14, 2009
EIT 284 EIT 304EIT 195
(Aulanier)
cavity
prominence
cavity
Filament material in dips of magnetic
field lines
Multiwavelength Nougat (thanks, Brigitte!)
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ISSI Jan. 14, 2009
Nougats and flares?
QuickTime™ and aTIFF (Uncompressed) decompressor
are needed to see this picture.
QuickTime™ and aTIFF (Uncompressed) decompressor
are needed to see this picture.
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ISSI Jan. 14, 2009
The Nougat’s basic messages
• If the PCTR is hotter than the corona surrounding it, the PCTR is unlikely to depend on static conduction as in normal TR models.
- We don’t really know if the nougats observed by SXT were hotter than the cavity, since the cavity temperature is hard to determine
• A filamentary (Chiuderi-type) PCTR would need to extend to heights well above the cold prominence material
• The PCTR is likely not to be a TR at all, just loops
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ISSI Jan. 14, 2009
Is a “PCTR” as suchobservable or even relevant?
• Transport perpendicular to the field may be negligible;
“conductive heating is completely insignificant”*• If so the TR-temperature regions may be physically
separated from the prominence• Large perpendicular gradients of gas pressure would
be expected even at low plasma beta
*Anzer & Heinzel 2008
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ISSI Jan. 14, 2009
Is “magnetic reconnection” observable or even relevant?
• The boundary between corona and prominence should correspond to a current system, which can support instabilities
• The standard reconnection model of a flare/CME involves shocks and jets, whose heating is not local
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ISSI Jan. 14, 2009
Conclusions
• The “Nougat” signature may just be space-filling hot branches of the actual prominence fields
• Need a proper electrodynamic theory to understand the true (perpendicular) boundary structure in the corona
• Need high resolution and sensitivity to understand how hot loops relate to prominence-bearing fields
• The term “PCTR” is probably misleading, except to a spectroscopist*
*n.b. PCTR ≈ PETR
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ISSI Jan. 14, 2009
Challenge
• Is it possible to show that the cavity itself does not consist of just the hot branches of the prominence field?