Attenuation of Coronal Magnetic Fields in Solar Microwave Bursts
Abstract
Based on the observed data by the Nobeyama Radio Observatory and the nonthermal gyrosynchrotron theory, the calculated magnetic field in a loop-like radio source of the 2001 October 23 flare attenuates from hundreds to tens of Gauss, except in the region with very weak magnetic fields. Meanwhile, the viewing angle between the magnetic field and line of sight has a similar attenuation from tens to around ten degrees, implying that the transverse magnetic component attenuates much faster than the longitudinal one. All of these results can be understood by the magnetic energy release process in solar flares. Moreover, the column density of nonthermal electrons decreases from 109-10 to 107-8 cm-2 during the flare, except in the region with very weak magnetic fields, where its value is larger than that with strong magnetic fields due to the mirroring effect. The calculated error and harmonic number of gyrofrequency better suit the region with strong magnetic fields.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- June 2015
- DOI:
- 10.1088/0004-637X/806/1/12
- Bibcode:
- 2015ApJ...806...12H
- Keywords:
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- Sun: corona;
- Sun: flares;
- Sun: magnetic fields;
- Sun: radio radiation