English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

Sheaths ahead of coronal mass ejections (CMEs) are large heliosphericstructures that form with CME expansion and propagation. Turbulent andcompressed sheaths contribute to the acceleration of particles in the coronaand in interplanetary space, but the relation of their internal structures toparticle energization is still relatively little studied. In particular, therole of sheaths in accelerating particles when the shock Mach number is low isa significant open problem. This work seeks to provide new insights on theinternal structure of CME sheaths with regard to energetic particleenhancements. A good opportunity to achieve this aim was provided byobservations of a sheath made by radially aligned spacecraft at 0.8 and $\sim$1 AU (Solar Orbiter, Wind, ACE and BepiColombo) on 19-21 April 2020. The sheathwas preceded by a weak shock. Energetic ion enhancements occurred at differentlocations within the sheath structure at Solar Orbiter and L1. Magneticfluctuation amplitudes at inertial-range scales increased in the sheathrelative to the upstream wind. However, when normalised to the local meanfield, fluctuation amplitudes did not increase significantly; magneticcompressibility of fluctuation also did not increase. Various substructureswere embedded within the sheath at the different spacecraft, including multipleheliospheric current sheet (HCS) crossings and a small-scale flux rope. At L1,the ion flux enhancement was associated with the HCS crossings, while at SolarOrbiter, the enhancement occurred within the rope. Substructures that are sweptfrom the upstream solar wind and compressed in the sheath can act asparticularly effective acceleration sites. A possible acceleration mechanism isbetatron acceleration associated with the small-scale flux rope and the warpedHCS in the sheath.

Multi-spacecraft observations of the structure of the sheath of an interplanetary coronal mass ejection and related energetic ion enhancement