Super- and sub-critical regions in shocks driven by radio-loud and radio-quiet CMEs
White-light coronagraphic images of Coronal Mass Ejections (CMEs) observed by SOHO/LASCO C2 have been used to estimate the density jump along the whole front of two CME-driven shocks. The two events are different in that the first one was a “radio-loud” fast CME, while the second one was a “radio qu...
| Main Authors: | , |
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| Format: | Article |
| Language: | English |
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Elsevier
2013-05-01
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| Series: | Journal of Advanced Research |
| Subjects: | |
| Online Access: | http://www.sciencedirect.com/science/article/pii/S2090123212000926 |
| _version_ | 1818918802054709248 |
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| author | Alessandro Bemporad Salvatore Mancuso |
| author_facet | Alessandro Bemporad Salvatore Mancuso |
| author_sort | Alessandro Bemporad |
| collection | DOAJ |
| description | White-light coronagraphic images of Coronal Mass Ejections (CMEs) observed by SOHO/LASCO C2 have been used to estimate the density jump along the whole front of two CME-driven shocks. The two events are different in that the first one was a “radio-loud” fast CME, while the second one was a “radio quiet” slow CME. From the compression ratios inferred along the shock fronts, we estimated the Alfvén Mach numbers for the general case of an oblique shock. It turns out that the “radio-loud” CME shock is initially super-critical around the shock center, while later on the whole shock becomes sub-critical. On the contrary, the shock associated with the “radio-quiet” CME is sub-critical at all times. This suggests that CME-driven shocks could be efficient particle accelerators at the shock nose only at the initiation phases of the event, if and when the shock is super-critical, while at later times they lose their energy and the capability to accelerate high energetic particles. |
| first_indexed | 2024-12-20T00:55:45Z |
| format | Article |
| id | doaj.art-93f0f20f13c1426a833ff97c742091cb |
| institution | Directory Open Access Journal |
| issn | 2090-1232 2090-1224 |
| language | English |
| last_indexed | 2024-12-20T00:55:45Z |
| publishDate | 2013-05-01 |
| publisher | Elsevier |
| record_format | Article |
| series | Journal of Advanced Research |
| spelling | doaj.art-93f0f20f13c1426a833ff97c742091cb2022-12-21T19:59:07ZengElsevierJournal of Advanced Research2090-12322090-12242013-05-014328729110.1016/j.jare.2012.09.005Super- and sub-critical regions in shocks driven by radio-loud and radio-quiet CMEsAlessandro BemporadSalvatore MancusoWhite-light coronagraphic images of Coronal Mass Ejections (CMEs) observed by SOHO/LASCO C2 have been used to estimate the density jump along the whole front of two CME-driven shocks. The two events are different in that the first one was a “radio-loud” fast CME, while the second one was a “radio quiet” slow CME. From the compression ratios inferred along the shock fronts, we estimated the Alfvén Mach numbers for the general case of an oblique shock. It turns out that the “radio-loud” CME shock is initially super-critical around the shock center, while later on the whole shock becomes sub-critical. On the contrary, the shock associated with the “radio-quiet” CME is sub-critical at all times. This suggests that CME-driven shocks could be efficient particle accelerators at the shock nose only at the initiation phases of the event, if and when the shock is super-critical, while at later times they lose their energy and the capability to accelerate high energetic particles.http://www.sciencedirect.com/science/article/pii/S2090123212000926Sun: coronaSun: radio radiationSun: coronal mass ejections (CMEs)Shock waves |
| spellingShingle | Alessandro Bemporad Salvatore Mancuso Super- and sub-critical regions in shocks driven by radio-loud and radio-quiet CMEs Journal of Advanced Research Sun: corona Sun: radio radiation Sun: coronal mass ejections (CMEs) Shock waves |
| title | Super- and sub-critical regions in shocks driven by radio-loud and radio-quiet CMEs |
| title_full | Super- and sub-critical regions in shocks driven by radio-loud and radio-quiet CMEs |
| title_fullStr | Super- and sub-critical regions in shocks driven by radio-loud and radio-quiet CMEs |
| title_full_unstemmed | Super- and sub-critical regions in shocks driven by radio-loud and radio-quiet CMEs |
| title_short | Super- and sub-critical regions in shocks driven by radio-loud and radio-quiet CMEs |
| title_sort | super and sub critical regions in shocks driven by radio loud and radio quiet cmes |
| topic | Sun: corona Sun: radio radiation Sun: coronal mass ejections (CMEs) Shock waves |
| url | http://www.sciencedirect.com/science/article/pii/S2090123212000926 |
| work_keys_str_mv | AT alessandrobemporad superandsubcriticalregionsinshocksdrivenbyradioloudandradioquietcmes AT salvatoremancuso superandsubcriticalregionsinshocksdrivenbyradioloudandradioquietcmes |