Element Abundances in Impulsive Solar Energetic-Particle Events
Impulsive solar energetic-particle (SEP) events were first distinguished as the streaming electrons that produce type III radio bursts as distinct from shock-induced type II bursts. They were then observed as the surprisingly enhanced <sup>3</sup>He-rich SEP events, which were also found...
| Main Author: | |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
MDPI AG
2023-10-01
|
| Series: | Universe |
| Subjects: | |
| Online Access: | https://www.mdpi.com/2218-1997/9/11/466 |
| _version_ | 1797457622163521536 |
|---|---|
| author | Donald V. Reames |
| author_facet | Donald V. Reames |
| author_sort | Donald V. Reames |
| collection | DOAJ |
| description | Impulsive solar energetic-particle (SEP) events were first distinguished as the streaming electrons that produce type III radio bursts as distinct from shock-induced type II bursts. They were then observed as the surprisingly enhanced <sup>3</sup>He-rich SEP events, which were also found to have element enhancements rising smoothly with the mass-to-charge ratio <i>A/Q</i> through the elements, even up to Pb. These impulsive SEPs have been found to originate during magnetic reconnection in solar jets where open magnetic field lines allow energetic particles to escape. In contrast, impulsive solar flares are produced when similar reconnection involves closed field lines where energetic ions are trapped on closed loops and dissipate their energy as X-rays, <i>γ</i>-rays, and heat. Abundance enhancements that are power laws in <i>A/Q</i> can be used to determine <i>Q</i> values and hence the coronal source temperature in the events. Results show no evidence of heating, implying reconnection and ion acceleration occur early, rapidly, and at low density. Proton and He excesses that contribute their own power law may identify events with reacceleration of SEPs by shock waves driven by accompanying fast, narrow coronal mass ejections (CMEs) in many of the stronger jets. |
| first_indexed | 2024-03-09T16:23:41Z |
| format | Article |
| id | doaj.art-7d8a15184ddd45969312c3c979a2f4b1 |
| institution | Directory Open Access Journal |
| issn | 2218-1997 |
| language | English |
| last_indexed | 2024-03-09T16:23:41Z |
| publishDate | 2023-10-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Universe |
| spelling | doaj.art-7d8a15184ddd45969312c3c979a2f4b12023-11-24T15:09:47ZengMDPI AGUniverse2218-19972023-10-0191146610.3390/universe9110466Element Abundances in Impulsive Solar Energetic-Particle EventsDonald V. Reames0Institute for Physical Science and Technology, University of Maryland, College Park, MD 20742, USAImpulsive solar energetic-particle (SEP) events were first distinguished as the streaming electrons that produce type III radio bursts as distinct from shock-induced type II bursts. They were then observed as the surprisingly enhanced <sup>3</sup>He-rich SEP events, which were also found to have element enhancements rising smoothly with the mass-to-charge ratio <i>A/Q</i> through the elements, even up to Pb. These impulsive SEPs have been found to originate during magnetic reconnection in solar jets where open magnetic field lines allow energetic particles to escape. In contrast, impulsive solar flares are produced when similar reconnection involves closed field lines where energetic ions are trapped on closed loops and dissipate their energy as X-rays, <i>γ</i>-rays, and heat. Abundance enhancements that are power laws in <i>A/Q</i> can be used to determine <i>Q</i> values and hence the coronal source temperature in the events. Results show no evidence of heating, implying reconnection and ion acceleration occur early, rapidly, and at low density. Proton and He excesses that contribute their own power law may identify events with reacceleration of SEPs by shock waves driven by accompanying fast, narrow coronal mass ejections (CMEs) in many of the stronger jets.https://www.mdpi.com/2218-1997/9/11/466solar energetic particlessolar system abundancessolar jetssolar flaresshock wavescoronal mass ejections |
| spellingShingle | Donald V. Reames Element Abundances in Impulsive Solar Energetic-Particle Events Universe solar energetic particles solar system abundances solar jets solar flares shock waves coronal mass ejections |
| title | Element Abundances in Impulsive Solar Energetic-Particle Events |
| title_full | Element Abundances in Impulsive Solar Energetic-Particle Events |
| title_fullStr | Element Abundances in Impulsive Solar Energetic-Particle Events |
| title_full_unstemmed | Element Abundances in Impulsive Solar Energetic-Particle Events |
| title_short | Element Abundances in Impulsive Solar Energetic-Particle Events |
| title_sort | element abundances in impulsive solar energetic particle events |
| topic | solar energetic particles solar system abundances solar jets solar flares shock waves coronal mass ejections |
| url | https://www.mdpi.com/2218-1997/9/11/466 |
| work_keys_str_mv | AT donaldvreames elementabundancesinimpulsivesolarenergeticparticleevents |