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)
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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, Professor 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 |
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