Imaging spectroscopy of spectral bump in a type II radio burst
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arXiv
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| Autores principales: | , , , , , , |
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| Formato: | Preprint |
| Publicado: |
2024
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| _version_ | 1866910389044772864 |
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| author | Zhang, Peijin Morosan, Diana E. Zucca, Pietro Normo, Sanna Dabrowski, Bartosz Krankowski, Andrzej Vocks, Christian |
| author_facet | Zhang, Peijin Morosan, Diana E. Zucca, Pietro Normo, Sanna Dabrowski, Bartosz Krankowski, Andrzej Vocks, Christian |
| contents | Context. Observations of solar type II radio bursts provide a unique opportunity to analyze the non-thermal electrons accelerated by coronal shocks and also to diagnose the plasma density distribution in the corona. However, there are very rare high-frequency resolution interferometric observations for type II radio bursts that are capable of tracking these electrons.
Aims. Recently, more spatially resolved high-resolution observations of type II radio bursts have been recorded with the Low-Frequency Array (LOFAR). Using these observations, we aim to track the location of a type II radio burst that experiences a sudden spectral bump.
Methods. Here, we present the first radio imaging observations for a type II burst with a spectral bump. We measure the variation in source location and frequency drift of the type II burst, and deduct the density distribution along its propagation direction.
Results. We identified a type II burst that experiences a sudden spectral bump in its frequency-time profile. The overall frequency drift rate is 0.06 MHz/s and it corresponds to an estimated speed of 295 km/s. The projected speed of the radio source obtained from imaging is 380 km/s towards the east direction. At the spectral bump, a deviation in the source locations of the type II split bands is observed. The band separation increases significantly in the north-south direction.
Conclusions. The spectral bump shows an 8 MHz deviation at 60 MHz which corresponds to a 25% decrease in the plasma density. The estimated crossing distance during the spectrum bump in type II is 29 Mm suggesting that this density variation occurs in a confined area. This indicates that the shock most likely encounters the upper extent of a coronal hole. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2403_19451 |
| institution | arXiv |
| publishDate | 2024 |
| record_format | arxiv |
| spellingShingle | Imaging spectroscopy of spectral bump in a type II radio burst Zhang, Peijin Morosan, Diana E. Zucca, Pietro Normo, Sanna Dabrowski, Bartosz Krankowski, Andrzej Vocks, Christian Solar and Stellar Astrophysics Context. Observations of solar type II radio bursts provide a unique opportunity to analyze the non-thermal electrons accelerated by coronal shocks and also to diagnose the plasma density distribution in the corona. However, there are very rare high-frequency resolution interferometric observations for type II radio bursts that are capable of tracking these electrons. Aims. Recently, more spatially resolved high-resolution observations of type II radio bursts have been recorded with the Low-Frequency Array (LOFAR). Using these observations, we aim to track the location of a type II radio burst that experiences a sudden spectral bump. Methods. Here, we present the first radio imaging observations for a type II burst with a spectral bump. We measure the variation in source location and frequency drift of the type II burst, and deduct the density distribution along its propagation direction. Results. We identified a type II burst that experiences a sudden spectral bump in its frequency-time profile. The overall frequency drift rate is 0.06 MHz/s and it corresponds to an estimated speed of 295 km/s. The projected speed of the radio source obtained from imaging is 380 km/s towards the east direction. At the spectral bump, a deviation in the source locations of the type II split bands is observed. The band separation increases significantly in the north-south direction. Conclusions. The spectral bump shows an 8 MHz deviation at 60 MHz which corresponds to a 25% decrease in the plasma density. The estimated crossing distance during the spectrum bump in type II is 29 Mm suggesting that this density variation occurs in a confined area. This indicates that the shock most likely encounters the upper extent of a coronal hole. |
| title | Imaging spectroscopy of spectral bump in a type II radio burst |
| topic | Solar and Stellar Astrophysics |
| url | https://arxiv.org/abs/2403.19451 |