The First Flare Observation with a New Solar Microwave Spectrometer Working in 35–40 GHz
The microwave spectrum contains valuable information about solar flares. Yet, the present spectral coverage is far from complete and broad data gaps exist above 20 GHz. Here we report the first flare (the X2.2 flare on 2022 April 20) observation of the newly built Chashan Broadband Solar millimeter...
| Main Authors: | , , , , , |
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| Format: | Article |
| Language: | English |
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IOP Publishing
2022-01-01
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| Series: | The Astrophysical Journal Letters |
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| Online Access: | https://doi.org/10.3847/2041-8213/acad02 |
| _version_ | 1797701961181560832 |
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| author | Fabao Yan Zhao Wu Ziqian Shang Bing Wang Lei Zhang Yao Chen |
| author_facet | Fabao Yan Zhao Wu Ziqian Shang Bing Wang Lei Zhang Yao Chen |
| author_sort | Fabao Yan |
| collection | DOAJ |
| description | The microwave spectrum contains valuable information about solar flares. Yet, the present spectral coverage is far from complete and broad data gaps exist above 20 GHz. Here we report the first flare (the X2.2 flare on 2022 April 20) observation of the newly built Chashan Broadband Solar millimeter spectrometer (CBS) working from 35 to 40 GHz. We use the CBS data of the new Moon to calibrate, and the simultaneous NoRP data at 35 GHz to cross-calibrate. The impulsive stage has three local peaks with the middle one being the strongest and the maximum flux density reaches ∼9300 solar flux unit at 35–40 GHz. The spectral index of the CBS data ( α _C ) for the major peak is mostly positive, indicating the gyrosynchrotron turnover frequency ( ν _t ) goes beyond 35–40 GHz. The frequency ν _t is smaller yet still larger than 20 GHz for most of the other two peaks according to the spectral fittings with NoRP-CBS data. The CBS index manifests the general rapid-hardening-then-softening trend for each peak and gradual hardening during the decay stage, agreeing with the fitted optically thin spectral index ( α _tn ) for ν _t < 35 GHz. In addition, the obtained turnover frequency ( ν _t ) during the whole impulsive stage correlates well with the corresponding intensity ( I _t ) according to a power-law dependence ( ${I}_{t}\propto {\nu }_{t}^{4.8}$ ) with a correlation coefficient of 0.82. This agrees with earlier studies on flares with low turnover frequency (≤17 GHz), yet it is being reported for the first time for events with a high turnover frequency (≥20 GHz). |
| first_indexed | 2024-03-12T04:44:17Z |
| format | Article |
| id | doaj.art-bd682cceb8054c8c82fe888899afc84c |
| institution | Directory Open Access Journal |
| issn | 2041-8205 |
| language | English |
| last_indexed | 2024-03-12T04:44:17Z |
| publishDate | 2022-01-01 |
| publisher | IOP Publishing |
| record_format | Article |
| series | The Astrophysical Journal Letters |
| spelling | doaj.art-bd682cceb8054c8c82fe888899afc84c2023-09-03T09:30:34ZengIOP PublishingThe Astrophysical Journal Letters2041-82052022-01-019421L1110.3847/2041-8213/acad02The First Flare Observation with a New Solar Microwave Spectrometer Working in 35–40 GHzFabao Yan0https://orcid.org/0000-0002-4451-7293Zhao Wu1https://orcid.org/0000-0002-6985-9863Ziqian Shang2https://orcid.org/0000-0002-8826-8006Bing Wang3Lei Zhang4Yao Chen5https://orcid.org/0000-0001-6449-8838Laboratory for Electromagnetic Detection, Institute of Space Sciences, Shandong University , Weihai, Shandong 264209, People’s Republic of ChinaLaboratory for Electromagnetic Detection, Institute of Space Sciences, Shandong University , Weihai, Shandong 264209, People’s Republic of ChinaLaboratory for Electromagnetic Detection, Institute of Space Sciences, Shandong University , Weihai, Shandong 264209, People’s Republic of ChinaLaboratory for Electromagnetic Detection, Institute of Space Sciences, Shandong University , Weihai, Shandong 264209, People’s Republic of ChinaLaboratory for Electromagnetic Detection, Institute of Space Sciences, Shandong University , Weihai, Shandong 264209, People’s Republic of ChinaLaboratory for Electromagnetic Detection, Institute of Space Sciences, Shandong University , Weihai, Shandong 264209, People’s Republic of China; Institute of Frontier and Interdisciplinary Science, Institute of Space Sciences, Shandong University , People’s Republic of China ; yaochen@sdu.edu.cnThe microwave spectrum contains valuable information about solar flares. Yet, the present spectral coverage is far from complete and broad data gaps exist above 20 GHz. Here we report the first flare (the X2.2 flare on 2022 April 20) observation of the newly built Chashan Broadband Solar millimeter spectrometer (CBS) working from 35 to 40 GHz. We use the CBS data of the new Moon to calibrate, and the simultaneous NoRP data at 35 GHz to cross-calibrate. The impulsive stage has three local peaks with the middle one being the strongest and the maximum flux density reaches ∼9300 solar flux unit at 35–40 GHz. The spectral index of the CBS data ( α _C ) for the major peak is mostly positive, indicating the gyrosynchrotron turnover frequency ( ν _t ) goes beyond 35–40 GHz. The frequency ν _t is smaller yet still larger than 20 GHz for most of the other two peaks according to the spectral fittings with NoRP-CBS data. The CBS index manifests the general rapid-hardening-then-softening trend for each peak and gradual hardening during the decay stage, agreeing with the fitted optically thin spectral index ( α _tn ) for ν _t < 35 GHz. In addition, the obtained turnover frequency ( ν _t ) during the whole impulsive stage correlates well with the corresponding intensity ( I _t ) according to a power-law dependence ( ${I}_{t}\propto {\nu }_{t}^{4.8}$ ) with a correlation coefficient of 0.82. This agrees with earlier studies on flares with low turnover frequency (≤17 GHz), yet it is being reported for the first time for events with a high turnover frequency (≥20 GHz).https://doi.org/10.3847/2041-8213/acad02Radio burstsSolar flaresSpectrometersSpectral index |
| spellingShingle | Fabao Yan Zhao Wu Ziqian Shang Bing Wang Lei Zhang Yao Chen The First Flare Observation with a New Solar Microwave Spectrometer Working in 35–40 GHz The Astrophysical Journal Letters Radio bursts Solar flares Spectrometers Spectral index |
| title | The First Flare Observation with a New Solar Microwave Spectrometer Working in 35–40 GHz |
| title_full | The First Flare Observation with a New Solar Microwave Spectrometer Working in 35–40 GHz |
| title_fullStr | The First Flare Observation with a New Solar Microwave Spectrometer Working in 35–40 GHz |
| title_full_unstemmed | The First Flare Observation with a New Solar Microwave Spectrometer Working in 35–40 GHz |
| title_short | The First Flare Observation with a New Solar Microwave Spectrometer Working in 35–40 GHz |
| title_sort | first flare observation with a new solar microwave spectrometer working in 35 40 ghz |
| topic | Radio bursts Solar flares Spectrometers Spectral index |
| url | https://doi.org/10.3847/2041-8213/acad02 |
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