INFERENCE OF HEATING PROPERTIES FROM "HOT" NON-FLARING PLASMAS IN ACTIVE REGION CORES. I. SINGLE NANOFLARES

• Published in: The Astrophysical journal Vol. 829; no. 1; pp. 31 - 43
• Main Authors: Barnes, W. T., Cargill, P. J., Bradshaw, S. J.
• Format: Journal Article
• Language: English
• Published: Philadelphia The American Astronomical Society 20.09.2016; IOP Publishing
• Subjects: Astrophysics; ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; Conduction; Conduction cooling; COOLING; Cooling effects; Coronal density; DENSITY; DISTRIBUTION; ELECTRONS; EMISSION; Emission measurements; ENTHALPY; EQUILIBRIUM; HEATING; HYDRODYNAMIC MODEL; hydrodynamics; IONIZATION; PLASMA; plasmas; Plasmas (physics); SIMULATION; STAR EVOLUTION; Sun: corona; Temperature range; THERMAL CONDUCTION; Thermal evolution
• ISSN: 0004-637X; 1538-4357
• DOI: 10.3847/0004-637X/829/1/31

ABSTRACT The properties that are expected of "hot" non-flaring plasmas due to nanoflare heating in active regions are investigated using hydrodynamic modeling tools, including a two-fluid development of the Enthalpy Based Thermal Evolution of Loops code. Here we study a single nanoflare and show that while simple models predict an emission measure distribution extending well above 10 MK, which is consistent with cooling by thermal conduction, many other effects are likely to limit the existence and detectability of such plasmas. These include: differential heating between electrons and ions, ionization non-equilibrium, and for short nanoflares, the time taken for the coronal density to increase. The most useful temperature range to look for this plasma, often called the "smoking gun" of nanoflare heating, lies between 106.6 and 107 K. Signatures of the actual heating may be detectable in some instances.