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An observational revisit of stationary type iv solar radio bursts

Stationary type IV solar radio bursts (IVSs) are broadband continuum emission observed at decimetric-decametric wavelength without apparent source motions. They are closely associated with solar flares and/or coronal mass ejections. Earlier studies on IVSs suffered from limited number of events, fre...

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Main Authors: Lv, Maoshui, Chen, Yao, Vasanth, V., Radzi, Mohd Shazwan, Abidin, Zamri Zainal, Monstein, Christian
Format: Article
Published: Springer 2021
Subjects:
Q Science (General)
QC Physics
Online Access:http://eprints.um.edu.my/28230/
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spelling my.um.eprints.282302022-07-27T09:13:00Z http://eprints.um.edu.my/28230/ An observational revisit of stationary type iv solar radio bursts Lv, Maoshui Chen, Yao Vasanth, V. Radzi, Mohd Shazwan Abidin, Zamri Zainal Monstein, Christian Q Science (General) QC Physics Stationary type IV solar radio bursts (IVSs) are broadband continuum emission observed at decimetric-decametric wavelength without apparent source motions. They are closely associated with solar flares and/or coronal mass ejections. Earlier studies on IVSs suffered from limited number of events, frequency coverage and available channels, and spatial resolution. Here we present an analysis on 34 IVSs using two-dimensional imaging data provided by Nancay Radioheliograh (NRH) at 10 frequencies from 150 to 445 MHz. The events are recorded from 2010 to 2014. We focus on general properties including the spatial dispersion of sources with frequency, brightness temperature (T-B) and corresponding spectra, and polarization. Main findings are: (i) In the majority of events (23/34) regular and systematic source dispersion with frequency can be clearly recognized. (ii) In most (31/34) events the maximum brightness temperature (T-BM(E)) exceeds 108 K, and exceeds 10(9) K in 23 events. The histogram distribution of T-BM(f), i.e. the maximum brightness temperature of a source at certain frequency (f) of a specific event (referred to as event-f source, there are 247 such sources in total) exhibits a clear declining trend with increasing frequencies. The dominant type of T-B spectra is power-law like with a negative index. (iii) In most events (30/34) the sense of polarization remains unchanged and the number of events with right and left-handed polarization are comparable. In 57% of all 247 event-f sources the level of polarization does not change considerably, in about 39% sources the level of polarization exhibits significant variation yet with a fixed sense, and in only 4% the sense of polarization changes. These results provide strong constraints on radiation mechanism of IVSs. Springer 2021-02-15 Article PeerReviewed Lv, Maoshui and Chen, Yao and Vasanth, V. and Radzi, Mohd Shazwan and Abidin, Zamri Zainal and Monstein, Christian (2021) An observational revisit of stationary type iv solar radio bursts. Solar Physics, 296 (2). ISSN 0038-0938, DOI https://doi.org/10.1007/s11207-021-01769-6 <https://doi.org/10.1007/s11207-021-01769-6>. 10.1007/s11207-021-01769-6
institution Universiti Malaya
building UM Library
collection Institutional Repository
continent Asia
country Malaysia
content_provider Universiti Malaya
content_source UM Research Repository
url_provider http://eprints.um.edu.my/
topic Q Science (General)
QC Physics
spellingShingle Q Science (General)
QC Physics
Lv, Maoshui
Chen, Yao
Vasanth, V.
Radzi, Mohd Shazwan
Abidin, Zamri Zainal
Monstein, Christian
An observational revisit of stationary type iv solar radio bursts
description Stationary type IV solar radio bursts (IVSs) are broadband continuum emission observed at decimetric-decametric wavelength without apparent source motions. They are closely associated with solar flares and/or coronal mass ejections. Earlier studies on IVSs suffered from limited number of events, frequency coverage and available channels, and spatial resolution. Here we present an analysis on 34 IVSs using two-dimensional imaging data provided by Nancay Radioheliograh (NRH) at 10 frequencies from 150 to 445 MHz. The events are recorded from 2010 to 2014. We focus on general properties including the spatial dispersion of sources with frequency, brightness temperature (T-B) and corresponding spectra, and polarization. Main findings are: (i) In the majority of events (23/34) regular and systematic source dispersion with frequency can be clearly recognized. (ii) In most (31/34) events the maximum brightness temperature (T-BM(E)) exceeds 108 K, and exceeds 10(9) K in 23 events. The histogram distribution of T-BM(f), i.e. the maximum brightness temperature of a source at certain frequency (f) of a specific event (referred to as event-f source, there are 247 such sources in total) exhibits a clear declining trend with increasing frequencies. The dominant type of T-B spectra is power-law like with a negative index. (iii) In most events (30/34) the sense of polarization remains unchanged and the number of events with right and left-handed polarization are comparable. In 57% of all 247 event-f sources the level of polarization does not change considerably, in about 39% sources the level of polarization exhibits significant variation yet with a fixed sense, and in only 4% the sense of polarization changes. These results provide strong constraints on radiation mechanism of IVSs.
format Article
author Lv, Maoshui
Chen, Yao
Vasanth, V.
Radzi, Mohd Shazwan
Abidin, Zamri Zainal
Monstein, Christian
author_facet Lv, Maoshui
Chen, Yao
Vasanth, V.
Radzi, Mohd Shazwan
Abidin, Zamri Zainal
Monstein, Christian
author_sort Lv, Maoshui
title An observational revisit of stationary type iv solar radio bursts
title_short An observational revisit of stationary type iv solar radio bursts
title_full An observational revisit of stationary type iv solar radio bursts
title_fullStr An observational revisit of stationary type iv solar radio bursts
title_full_unstemmed An observational revisit of stationary type iv solar radio bursts
title_sort observational revisit of stationary type iv solar radio bursts
publisher Springer
publishDate 2021
url http://eprints.um.edu.my/28230/
_version_ 1739828448258424832
score 13.211869

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