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| Main Authors: | , , , , |
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| Format: | Preprint |
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2025
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| Subjects: | |
| Online Access: | https://arxiv.org/abs/2504.17667 |
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| _version_ | 1866915257118621696 |
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| author | Majury, Luke Milligan, Ryan Butler, Elizabeth Greatorex, Harry Kazachenko, Maria |
| author_facet | Majury, Luke Milligan, Ryan Butler, Elizabeth Greatorex, Harry Kazachenko, Maria |
| contents | The Lyman-alpha (Lyα;1216 Å) line is the brightest emission line in the quiescent solar spectrum and radiates a significant fraction of the available nonthermal energy during flares. Despite its importance, there is a lack of detailed studies of Lyα spectral variability during flares. Recently, spectrally resolved Lyα flare observations from the SORCE/SOLSTICE instrument have become available. This study examines Lyα spectral variability and its relationship with HXR emission from nonthermal electrons, using observations of two M-class flares from SORCE/SOLSTICE and RHESSI. Imaging observations from STEREO/SECCHI EUVI and SDO/AIA provide further context. Enhancements across the Lyα line profile were found to closely correlate with bursts of HXR emission, suggesting a primarily nonthermal origin. Red enhancement asymmetries at the peak of each flare were attributed to chromospheric evaporation, while blue wing enhancement and blue asymmetry were linked to a bright filament-eruption seen in SDO/AIA 1600 Å images. These findings contribute to the understanding of spectral Lyα variability during flares and highlight the need for future studies using a higher quality and quantity of spectral Lyα flare observations. Such studies will further characterise the physical mechanisms driving Lyα flare variability. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2504_17667 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Spectral Irradiance Variability in Lyman-Alpha Emission During Solar Flares Majury, Luke Milligan, Ryan Butler, Elizabeth Greatorex, Harry Kazachenko, Maria Solar and Stellar Astrophysics The Lyman-alpha (Lyα;1216 Å) line is the brightest emission line in the quiescent solar spectrum and radiates a significant fraction of the available nonthermal energy during flares. Despite its importance, there is a lack of detailed studies of Lyα spectral variability during flares. Recently, spectrally resolved Lyα flare observations from the SORCE/SOLSTICE instrument have become available. This study examines Lyα spectral variability and its relationship with HXR emission from nonthermal electrons, using observations of two M-class flares from SORCE/SOLSTICE and RHESSI. Imaging observations from STEREO/SECCHI EUVI and SDO/AIA provide further context. Enhancements across the Lyα line profile were found to closely correlate with bursts of HXR emission, suggesting a primarily nonthermal origin. Red enhancement asymmetries at the peak of each flare were attributed to chromospheric evaporation, while blue wing enhancement and blue asymmetry were linked to a bright filament-eruption seen in SDO/AIA 1600 Å images. These findings contribute to the understanding of spectral Lyα variability during flares and highlight the need for future studies using a higher quality and quantity of spectral Lyα flare observations. Such studies will further characterise the physical mechanisms driving Lyα flare variability. |
| title | Spectral Irradiance Variability in Lyman-Alpha Emission During Solar Flares |
| topic | Solar and Stellar Astrophysics |
| url | https://arxiv.org/abs/2504.17667 |