Frequency rising sub-THz emission from solar flare ribbons

Kontar, E.P. , Motorina, G.G., Jeffrey, N.L.S. , Tsap, Y.T., Fleishman, G.D. and Stepanov, A.V. (2018) Frequency rising sub-THz emission from solar flare ribbons. Astronomy and Astrophysics, 620, A95. (doi:10.1051/0004-6361/201834124)

[img]
Preview
Text
174734.pdf - Accepted Version

552kB

Abstract

Observations of solar flares at sub-THz frequencies (millimetre and sub-millimetre wavelengths) over the last two decades often show a spectral component rising with frequency. Unlike a typical gyrosynchrotron spectrum decreasing with frequency or a weak thermal component from hot coronal plasma, the observations can demonstrate a high flux level (up to ∼104 solar flux units at 0.4 THz) and fast variability on sub-second timescales. Although, many models have been put forward to explain the puzzling observations, none of them has clear observational support. Here we propose a scenario to explain the intriguing sub-THz observations. We show that the model, based on free-free emission from the plasma of flare ribbons at temperatures 104 − 106 K, is consistent with all existing observations of frequency-rising sub-THz flare emission. The model provides a temperature diagnostic of the flaring chromosphere and suggests fast heating and cooling of the dense transition region plasma.

Item Type:Articles
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Motorina, Ms Galina and Kontar, Dr Eduard and Jeffrey, Dr Natasha
Authors: Kontar, E.P., Motorina, G.G., Jeffrey, N.L.S., Tsap, Y.T., Fleishman, G.D., and Stepanov, A.V.
College/School:College of Science and Engineering > School of Physics and Astronomy
Journal Name:Astronomy and Astrophysics
Publisher:EDP Sciences
ISSN:0004-6361
ISSN (Online):1432-0746
Copyright Holders:Copyright © 2018 ESO
First Published:First published in Astronomy and Astrophysics 620:A95
Publisher Policy:Reproduced in accordance with the copyright policy of the publisher
Related URLs:

University Staff: Request a correction | Enlighten Editors: Update this record

Project CodeAward NoProject NamePrincipal InvestigatorFunder's NameFunder RefLead Dept
631581Consolidated grant in solar and astrophysical plasmasLyndsay FletcherScience & Technology Facilities Council (STFC)ST/L000741/1S&E P&A - PHYSICS & ASTRONOMY