First Detection of Low-frequency Striae in Interplanetary Type III Radio Bursts
We report the first detection of type III solar radio burst striae in the 30–80 kHz range, observed by the Cluster-4 spacecraft during an exceptionally quiet solar period. These low-frequency fine structures, which drift slowly in frequency and exhibit narrow bandwidths, provide a novel diagnostic o...
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IOP Publishing
2025-01-01
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| Series: | The Astrophysical Journal Letters |
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| Online Access: | https://doi.org/10.3847/2041-8213/add688 |
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| author | Vratislav Krupar Eduard P. Kontar Jan Soucek Lynn B. Wilson III Adam Szabo Oksana Kruparova Hamish A. S. Reid Mychajlo Hajos David Pisa Ondrej Santolik Milan Maksimovic Jolene S. Pickett |
| author_facet | Vratislav Krupar Eduard P. Kontar Jan Soucek Lynn B. Wilson III Adam Szabo Oksana Kruparova Hamish A. S. Reid Mychajlo Hajos David Pisa Ondrej Santolik Milan Maksimovic Jolene S. Pickett |
| author_sort | Vratislav Krupar |
| collection | DOAJ |
| description | We report the first detection of type III solar radio burst striae in the 30–80 kHz range, observed by the Cluster-4 spacecraft during an exceptionally quiet solar period. These low-frequency fine structures, which drift slowly in frequency and exhibit narrow bandwidths, provide a novel diagnostic of plasma processes in the inner heliosphere. The detected striae, interpreted as fundamental plasma emission, exhibit a frequency drift rate of 0.328 Hz s ^−1 and a bandwidth of 1.3 kHz. By combining high-resolution radio observations with well-calibrated in situ electron velocity distribution function data from the Wind spacecraft, we characterized the plasma properties of the burst source region near 0.32 au. Our analysis estimates relative density fluctuations, at the effective turbulence scale length, as approximately 3.4% (inferred from striae bandwidths), 0.62% (from intensity fluctuations), and 3.5% (from a heliocentric distance-based empirical model). These findings offer critical insights into small-scale density inhomogeneities and turbulence that affect electron beam propagation. This study underscores the potential of combining well-calibrated in situ electron data with radio burst measurements to probe the physical conditions of the solar wind and to refine our understanding of solar radio bursts across a broad frequency range. |
| format | Article |
| id | doaj-art-98f69656cd104634872ef4f3a6ea2cd3 |
| institution | Kabale University |
| issn | 2041-8205 |
| language | English |
| publishDate | 2025-01-01 |
| publisher | IOP Publishing |
| record_format | Article |
| series | The Astrophysical Journal Letters |
| spelling | doaj-art-98f69656cd104634872ef4f3a6ea2cd32025-08-20T03:47:28ZengIOP PublishingThe Astrophysical Journal Letters2041-82052025-01-019852L2710.3847/2041-8213/add688First Detection of Low-frequency Striae in Interplanetary Type III Radio BurstsVratislav Krupar0https://orcid.org/0000-0001-6185-3945Eduard P. Kontar1https://orcid.org/0000-0002-8078-0902Jan Soucek2https://orcid.org/0000-0003-0462-6804Lynn B. Wilson III3https://orcid.org/0000-0002-4313-1970Adam Szabo4https://orcid.org/0000-0003-3255-9071Oksana Kruparova5https://orcid.org/0000-0002-1122-6422Hamish A. S. Reid6https://orcid.org/0000-0002-6287-3494Mychajlo Hajos7https://orcid.org/0000-0002-6163-6665David Pisa8https://orcid.org/0000-0002-1322-7576Ondrej Santolik9https://orcid.org/0000-0002-4891-9273Milan Maksimovic10https://orcid.org/0000-0001-6172-5062Jolene S. Pickett11https://orcid.org/0000-0001-6399-3351Goddard Planetary Heliophysics Institute, University of Maryland , Baltimore County, Baltimore, MD 21250, USA; Heliospheric Physics Laboratory, Heliophysics Division, NASA Goddard Space Flight Center , Greenbelt, MD 20771, USASchool of Physics & Astronomy, University of Glasgow , Glasgow, G12 8QQ, UKDepartment of Space Physics, Institute of Atmospheric Physics of the Czech Academy of Sciences , 141 00 Prague, Czech RepublicHeliospheric Physics Laboratory, Heliophysics Division, NASA Goddard Space Flight Center , Greenbelt, MD 20771, USAHeliospheric Physics Laboratory, Heliophysics Division, NASA Goddard Space Flight Center , Greenbelt, MD 20771, USAGoddard Planetary Heliophysics Institute, University of Maryland , Baltimore County, Baltimore, MD 21250, USA; Heliospheric Physics Laboratory, Heliophysics Division, NASA Goddard Space Flight Center , Greenbelt, MD 20771, USAMullard Space Science Laboratory, University College London , Holmbury St. Mary, Dorking, Surrey, RH5 6NT, UKDepartment of Space Physics, Institute of Atmospheric Physics of the Czech Academy of Sciences , 141 00 Prague, Czech RepublicDepartment of Space Physics, Institute of Atmospheric Physics of the Czech Academy of Sciences , 141 00 Prague, Czech RepublicDepartment of Space Physics, Institute of Atmospheric Physics of the Czech Academy of Sciences , 141 00 Prague, Czech Republic; Faculty of Mathematics and Physics, Charles University , 121 16 Prague, Czech RepublicLESIA, Observatoire de Paris, Université PSL , CNRS, Sorbonne Université, Université de Paris, F-92195 Meudon, FranceDepartment of Physics and Astronomy, The University of Iowa , Iowa City, IA 52242, USAWe report the first detection of type III solar radio burst striae in the 30–80 kHz range, observed by the Cluster-4 spacecraft during an exceptionally quiet solar period. These low-frequency fine structures, which drift slowly in frequency and exhibit narrow bandwidths, provide a novel diagnostic of plasma processes in the inner heliosphere. The detected striae, interpreted as fundamental plasma emission, exhibit a frequency drift rate of 0.328 Hz s ^−1 and a bandwidth of 1.3 kHz. By combining high-resolution radio observations with well-calibrated in situ electron velocity distribution function data from the Wind spacecraft, we characterized the plasma properties of the burst source region near 0.32 au. Our analysis estimates relative density fluctuations, at the effective turbulence scale length, as approximately 3.4% (inferred from striae bandwidths), 0.62% (from intensity fluctuations), and 3.5% (from a heliocentric distance-based empirical model). These findings offer critical insights into small-scale density inhomogeneities and turbulence that affect electron beam propagation. This study underscores the potential of combining well-calibrated in situ electron data with radio burst measurements to probe the physical conditions of the solar wind and to refine our understanding of solar radio bursts across a broad frequency range.https://doi.org/10.3847/2041-8213/add688Solar radio emissionSolar windSolar coronal radio emissionInterplanetary turbulencePlasma astrophysics |
| spellingShingle | Vratislav Krupar Eduard P. Kontar Jan Soucek Lynn B. Wilson III Adam Szabo Oksana Kruparova Hamish A. S. Reid Mychajlo Hajos David Pisa Ondrej Santolik Milan Maksimovic Jolene S. Pickett First Detection of Low-frequency Striae in Interplanetary Type III Radio Bursts The Astrophysical Journal Letters Solar radio emission Solar wind Solar coronal radio emission Interplanetary turbulence Plasma astrophysics |
| title | First Detection of Low-frequency Striae in Interplanetary Type III Radio Bursts |
| title_full | First Detection of Low-frequency Striae in Interplanetary Type III Radio Bursts |
| title_fullStr | First Detection of Low-frequency Striae in Interplanetary Type III Radio Bursts |
| title_full_unstemmed | First Detection of Low-frequency Striae in Interplanetary Type III Radio Bursts |
| title_short | First Detection of Low-frequency Striae in Interplanetary Type III Radio Bursts |
| title_sort | first detection of low frequency striae in interplanetary type iii radio bursts |
| topic | Solar radio emission Solar wind Solar coronal radio emission Interplanetary turbulence Plasma astrophysics |
| url | https://doi.org/10.3847/2041-8213/add688 |
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