On the million-degree signature of spicules
| Title: | On the million-degree signature of spicules |
|---|---|
| Authors: | Bose, Souvik, Joshi, Jayant, Testa, Paola, De Pontieu, Bart |
| Publication Year: | 2025 |
| Collection: | Astrophysics |
| Subject Terms: | Astrophysics - Solar and Stellar Astrophysics |
| More Details: | Spicules have often been proposed as substantial contributors toward the mass and energy balance of the solar corona. While their transition region (TR) counterpart has unequivocally been established over the past decade, the observations concerning the coronal contribution of spicules have often been contested. This is mainly attributed to the lack of adequate coordinated observations, their small spatial scales, highly dynamic nature, and complex multi-thermal evolution, which are often observed at the limit of our current observational facilities. Therefore, it remains unclear how much heating occurs in association with spicules to coronal temperatures. In this study, we use coordinated high-resolution observations of the solar chromosphere, TR, and corona of a quiet Sun region and a coronal hole with the Interface Region Imaging Spectrograph (IRIS) and the Atmospheric Imaging Assembly (AIA) to investigate the (lower) coronal ($\sim$1MK) emission associated with spicules. We perform differential emission measure (DEM) analysis on the AIA passbands using basis pursuit and a newly developed technique based on Tikhonov regularization to probe the thermal structure of the spicular environment at coronal temperatures. We find that the EM maps at 1 MK reveal the presence of ubiquitous, small-scale jets with a clear spatio-temporal coherence with the spicules observed in the IRIS/TR passband. Detailed space-time analysis of the chromospheric, TR, and EM maps show unambiguous evidence of rapidly outward propagating spicules with strong emission (2--3 times higher than the background) at 1 MK. Our findings are consistent with previously reported MHD simulations that show heating to coronal temperatures associated with spicules. Comment: Accepted for publication in The Astrophysical Journal Letters, 13 pages, 5 main figures and 7 supplementary figures in the Appendix |
| Document Type: | Working Paper |
| Access URL: | http://arxiv.org/abs/2503.08887 |
| Accession Number: | edsarx.2503.08887 |
| Database: | arXiv |
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| Items | – Name: Title Label: Title Group: Ti Data: On the million-degree signature of spicules – Name: Author Label: Authors Group: Au Data: <searchLink fieldCode="AR" term="%22Bose%2C+Souvik%22">Bose, Souvik</searchLink><br /><searchLink fieldCode="AR" term="%22Joshi%2C+Jayant%22">Joshi, Jayant</searchLink><br /><searchLink fieldCode="AR" term="%22Testa%2C+Paola%22">Testa, Paola</searchLink><br /><searchLink fieldCode="AR" term="%22De+Pontieu%2C+Bart%22">De Pontieu, Bart</searchLink> – Name: DatePubCY Label: Publication Year Group: Date Data: 2025 – Name: Subset Label: Collection Group: HoldingsInfo Data: Astrophysics – Name: Subject Label: Subject Terms Group: Su Data: <searchLink fieldCode="DE" term="%22Astrophysics+-+Solar+and+Stellar+Astrophysics%22">Astrophysics - Solar and Stellar Astrophysics</searchLink> – Name: Abstract Label: Description Group: Ab Data: Spicules have often been proposed as substantial contributors toward the mass and energy balance of the solar corona. While their transition region (TR) counterpart has unequivocally been established over the past decade, the observations concerning the coronal contribution of spicules have often been contested. This is mainly attributed to the lack of adequate coordinated observations, their small spatial scales, highly dynamic nature, and complex multi-thermal evolution, which are often observed at the limit of our current observational facilities. Therefore, it remains unclear how much heating occurs in association with spicules to coronal temperatures. In this study, we use coordinated high-resolution observations of the solar chromosphere, TR, and corona of a quiet Sun region and a coronal hole with the Interface Region Imaging Spectrograph (IRIS) and the Atmospheric Imaging Assembly (AIA) to investigate the (lower) coronal ($\sim$1MK) emission associated with spicules. We perform differential emission measure (DEM) analysis on the AIA passbands using basis pursuit and a newly developed technique based on Tikhonov regularization to probe the thermal structure of the spicular environment at coronal temperatures. We find that the EM maps at 1 MK reveal the presence of ubiquitous, small-scale jets with a clear spatio-temporal coherence with the spicules observed in the IRIS/TR passband. Detailed space-time analysis of the chromospheric, TR, and EM maps show unambiguous evidence of rapidly outward propagating spicules with strong emission (2--3 times higher than the background) at 1 MK. Our findings are consistent with previously reported MHD simulations that show heating to coronal temperatures associated with spicules.<br />Comment: Accepted for publication in The Astrophysical Journal Letters, 13 pages, 5 main figures and 7 supplementary figures in the Appendix – Name: TypeDocument Label: Document Type Group: TypDoc Data: Working Paper – Name: URL Label: Access URL Group: URL Data: <link linkTarget="URL" linkTerm="http://arxiv.org/abs/2503.08887" linkWindow="_blank">http://arxiv.org/abs/2503.08887</link> – Name: AN Label: Accession Number Group: ID Data: edsarx.2503.08887 |
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| RecordInfo | BibRecord: BibEntity: Subjects: – SubjectFull: Astrophysics - Solar and Stellar Astrophysics Type: general Titles: – TitleFull: On the million-degree signature of spicules Type: main BibRelationships: HasContributorRelationships: – PersonEntity: Name: NameFull: Bose, Souvik – PersonEntity: Name: NameFull: Joshi, Jayant – PersonEntity: Name: NameFull: Testa, Paola – PersonEntity: Name: NameFull: De Pontieu, Bart IsPartOfRelationships: – BibEntity: Dates: – D: 11 M: 03 Type: published Y: 2025 |
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