[Loops] chromospheric nanoflares as the source of coronal plasma

[Klimchuk, James A. (GSFC-6710)]

Dear friends,

    You might be interested in a paper that Steve and I just submitted on "Chromospheric Nanoflares as the Source of Coronal Plasma." It can be downloaded at http://arxiv.org/abs/1405.1708. The abstract is below.

Cheers,
Jim

It has been suggested that the hot plasma of the solar corona comes primarily from impulsive heating events, or nanoflares, that occur in the lower atmosphere, either in the upper part of the ordinary chromosphere or at the tips of type II spicules. We test this idea with a series of hydrodynamic simulations. We find that synthetic Fe XII (195) and Fe XIV (274) line profiles generated from the simulations disagree dramatically with actual observations. The integrated line intensities are much too faint; the blue shifts are much too fast; the blue-red asymmetries are much too large; and the emission is confined to low altitudes. We conclude that chromospheric nanoflares are not a primary source of hot coronal plasma. Such events may play an important role in producing the chromosphere and powering its intense radiation, but they do not, in general, raise the temperature of the plasma to coronal values. Those cases where coronal temperatures are reached must be relatively uncommon. The observed profiles of Fe XII and Fe XIV come primarily from plasma that is heated in the corona itself, either by coronal nanoflares or a quasi-steady coronal heating process. Chromospheric nanoflares might play a role in generating waves that provide this coronal heating.


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James A. Klimchuk
NASA Goddard Space Flight Center
Solar Physics Lab, Code 671
Bldg. 21, Rm. 158
Greenbelt, MD  20771
USA

Phone:  1-301-286-9060
Fax:      1-301-286-7194
E-mail:  James.A.Klimchuk at nasa.gov<mailto:James.A.Klimchuk at nasa.gov>
Homepage:  http://science.gsfc.nasa.gov/sed/index.cfm?fuseAction=people.jumpBio&&iPhonebookId=15844

No endorsement by NASA is implied for any correspondence related to my official role in professional organizations.

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