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Title: Are chromospheric nanoflares a primary source of coronal plasma?

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 blueshifts 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 thatmore » provide this coronal heating.« less
Authors:
 [1] ;  [2]
  1. NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States)
  2. Department of Physics and Astronomy, Rice University, Houston, TX 77005 (United States)
Publication Date:
OSTI Identifier:
22365348
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 791; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ALTITUDE; ASYMMETRY; CHROMOSPHERE; EMISSION; HEATING; HOT PLASMA; SIMULATION; SOLAR CORONA; SOLAR PROMINENCES; SUN; ULTRAVIOLET RADIATION