Formation of the Shock and the Sheath Region Ahead of Coronal Mass Ejections: Insight from STEREO Measurements
Abstract
We conducted a detailed analysis of in situ measurements of Coronal Mass Ejections (CMEs) by the twin STEREO spacecraft from 2007-2016. We classified the CME events into three major categories: CMEs with sheath structures, neither sheath nor shock, and sheaths but no shocks (or sometimes shock-like discontinuities). For CMEs with shocks, we performed a linear least-square fitting of the solar wind speed in the sheath region. We divided these CME driven sheaths into four subcategories based on a predefined criterion. We then performed a superposed epoch analysis of these subcategories individually using normalized time. We also performed the same superposed epoch analysis for CMEs which don't have shocks and sheaths and for CMEs which drive shock-like discontinuities. Analyzing the average magnetic field and plasma profile in the pre-sheath, sheath, and ejecta regions, we examined the difference in sheath structures associated with CME events driving either a shock or shock-like discontinuity at L1. We also identified the pre-sheath solar wind conditions which enables a CME to drive a shock.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFMSH42A..08S
- Keywords:
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- 7513 Coronal mass ejections;
- SOLAR PHYSICS;
- ASTROPHYSICS;
- AND ASTRONOMY;
- 7514 Energetic particles;
- SOLAR PHYSICS;
- ASTROPHYSICS;
- AND ASTRONOMY;
- 7536 Solar activity cycle;
- SOLAR PHYSICS;
- ASTROPHYSICS;
- AND ASTRONOMY;
- 7974 Solar effects;
- SPACE WEATHER