Imaging a large coronal loop using type U solar radio burst interferometry
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arXiv
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| Main Authors: | , , , , , , |
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| Format: | Preprint |
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2024
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| _version_ | 1866913225833971712 |
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| author | Zhang, Jinge Reid, Hamish A. S. Carley, Eoin Lamy, Laurent Zucca, Pietro Zhang, Peijin Cecconi, Baptiste |
| author_facet | Zhang, Jinge Reid, Hamish A. S. Carley, Eoin Lamy, Laurent Zucca, Pietro Zhang, Peijin Cecconi, Baptiste |
| contents | Solar radio U-bursts are generated by electron beams traveling along closed magnetic loops in the solar corona. Low-frequency ($<$ 100 MHz) U-bursts serve as powerful diagnostic tools for studying large-sized coronal loops that extend into the middle corona. However, the positive frequency drift component (descending leg) of U-bursts has received less attention in previous studies, as the descending radio flux is weak. In this study, we utilized LOFAR interferometric solar imaging data from a U-burst that has a significant descending leg component, observed between 10 to 90 MHz on June 5th, 2020. By analyzing the radio source centroid positions, we determined the beam velocities and physical parameters of a large coronal magnetic loop that reached just about 1.3 $\rm{R_{\odot}}$ in altitude. At this altitude, we found the plasma temperature to be around 1.1 MK, the plasma pressure around 0.20 $\rm{mdyn,cm^{-2}}$, and the minimum magnetic field strength around 0.07 G. The similarity in physical properties determined from the image suggests a symmetric loop. The average electron beam velocity on the ascending leg was found to be 0.21 c, while it was 0.14 c on the descending leg. This apparent deceleration is attributed to a decrease in the range of electron energies that resonate with Langmuir waves, likely due to the positive background plasma density gradient along the downward loop leg. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2402_04822 |
| institution | arXiv |
| publishDate | 2024 |
| record_format | arxiv |
| spellingShingle | Imaging a large coronal loop using type U solar radio burst interferometry Zhang, Jinge Reid, Hamish A. S. Carley, Eoin Lamy, Laurent Zucca, Pietro Zhang, Peijin Cecconi, Baptiste Solar and Stellar Astrophysics Solar radio U-bursts are generated by electron beams traveling along closed magnetic loops in the solar corona. Low-frequency ($<$ 100 MHz) U-bursts serve as powerful diagnostic tools for studying large-sized coronal loops that extend into the middle corona. However, the positive frequency drift component (descending leg) of U-bursts has received less attention in previous studies, as the descending radio flux is weak. In this study, we utilized LOFAR interferometric solar imaging data from a U-burst that has a significant descending leg component, observed between 10 to 90 MHz on June 5th, 2020. By analyzing the radio source centroid positions, we determined the beam velocities and physical parameters of a large coronal magnetic loop that reached just about 1.3 $\rm{R_{\odot}}$ in altitude. At this altitude, we found the plasma temperature to be around 1.1 MK, the plasma pressure around 0.20 $\rm{mdyn,cm^{-2}}$, and the minimum magnetic field strength around 0.07 G. The similarity in physical properties determined from the image suggests a symmetric loop. The average electron beam velocity on the ascending leg was found to be 0.21 c, while it was 0.14 c on the descending leg. This apparent deceleration is attributed to a decrease in the range of electron energies that resonate with Langmuir waves, likely due to the positive background plasma density gradient along the downward loop leg. |
| title | Imaging a large coronal loop using type U solar radio burst interferometry |
| topic | Solar and Stellar Astrophysics |
| url | https://arxiv.org/abs/2402.04822 |