Magnetic-reconnection exhausts in the sheath of magnetic clouds

Feng, H. Q.; Wang, Jiemin

doi:10.1051/0004-6361/201322522

Cited by 25 publications

(15 citation statements)

References 37 publications

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“…Gosling et al (1995) discuss a mechanism in which part of the field lines at the MC periphery are magnetically connected to the outer heliosphere after reconnection occurred. Case studies (Dasso et al 2006(Dasso et al , 2007Feng & Wang 2013) and a statistical analysis of a large sample of events (Ruffenach et al 2015) indicate that an MC can suffer magnetic erosion at its front during its travel in the heliosphere, forming a back region with mixed properties of both MC and ambient solar wind (Dasso et al 2006;Ruffenach et al 2012). Thus, because MCs are 3D structures, it is possible that this erosion only happens at various specific locations along the flux rope.…”

Section: Results For the Average Profilesmentioning

confidence: 99%

Superposed epoch study of ICME sub-structures near Earth and their effects on Galactic cosmic rays

Masías-Meza

Dasso

Démoulin

et al. 2016

A&A

113

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Context. Interplanetary coronal mass ejections (ICMEs) are the interplanetary manifestations of solar eruptions. The overtaken solar wind forms a sheath of compressed plasma at the front of ICMEs. Magnetic clouds (MCs) are a subset of ICMEs with specific properties (e.g. the presence of a flux rope). When ICMEs pass near Earth, ground observations indicate that the flux of Galactic cosmic rays (GCRs) decreases. Aims. The main aims of this paper are to find common plasma and magnetic properties of different ICME sub-structures and which ICME properties affect the flux of GCRs near Earth. Methods. We used a superposed epoch method applied to a large set of ICMEs observed in situ by the spacecraft ACE, between 1998 and 2006. We also applied a superposed epoch analysis on GCRs time series observed with the McMurdo neutron monitors. Results. We find that slow MCs at 1 AU have on average more massive sheaths. We conclude that this is because they are more effectively slowed down by drag during their travel from the Sun. Slow MCs also have a more symmetric magnetic field and sheaths expanding similarly as their following MC, while in contrast, fast MCs have an asymmetric magnetic profile and a sheath in compression. In all types of MCs, we find that the proton density and the temperature and the magnetic fluctuations can diffuse within the front of the MC due to 3D reconnection. Finally, we derive a quantitative model that describes the decrease in cosmic rays as a function of the amount of magnetic fluctuations and field strength. Conclusions. The obtained typical profiles of sheath, MC and GCR properties corresponding to slow, middle, and fast ICMEs, can be used for forecasting or modelling these events, and to better understand the transport of energetic particles in ICMEs. They are also useful for improving future operative space weather activities.

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Section: Results For the Average Profilesmentioning

confidence: 99%

Superposed epoch study of ICME sub-structures near Earth and their effects on Galactic cosmic rays

Masías-Meza

Dasso

Démoulin

et al. 2016

A&A

113

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“…18h their beta distribution is biased to β < 2 and magnetic reconnection may occur during higher plasma beta conditions if the shear angle of the magnetic field across the current sheet is sufficiently large (Phan et al 2013). Indeed, Feng and Wang (2013) found five reconnection exhausts within a high-beta sheath of an MC observed on 18-20 October, 1995.…”

Section: Sheath Signatures and Propertiesmentioning

confidence: 99%

“…The neighbourhood of the sheath-ICME boundary is a much less studied region in terms of plasma wave activity. The accumulation of plasma and magnetic field from different sources during the interplanetary formation of the sheath introduces interfaces that are suitable places to find plasma discontinuities and reconnection exhausts (e.g., Kataoka et al 2005;Feng and Wang 2013). Magnetic reconnection favours low plasma beta conditions (β < 2) (e.g., Scurry et al 1994).…”

Section: Sheath Signatures and Propertiesmentioning

confidence: 99%

Coronal mass ejections and their sheath regions in interplanetary space

Kilpua

Koskinen

Pulkkinen

2017

Living Rev Sol Phys

356

360

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Interplanetary coronal mass ejections (ICMEs) are large-scale heliospheric transients that originate from the Sun. When an ICME is sufficiently faster than the preceding solar wind, a shock wave develops ahead of the ICME. The turbulent region between the shock and the ICME is called the sheath region. ICMEs and their sheaths and shocks are all interesting structures from the fundamental plasma physics viewpoint. They are also key drivers of space weather disturbances in the heliosphere and planetary environments. ICME-driven shock waves can accelerate charged particles to high energies. Sheaths and ICMEs drive practically all intense geospace storms at the Earth, and they can also affect dramatically the planetary radiation environments and atmospheres. This review focuses on the current understanding of observational signatures and properties of ICMEs and the associated sheath regions based on five decades of studies. In addition, we discuss modelling of ICMEs and many fundamental outstanding questions on their origin, evolution and effects, largely due to the limitations of single spacecraft observations of these macro-scale structures. We also present current understanding of space weather consequences of these large-scale solar wind structures, including effects at the other Solar System planets and exoplanets. We specially emphasize the different origin, properties and consequences of the sheaths and ICMEs.

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“…Obviously, more event studies are needed to confirm these findings. However, previous studies have also shown that compressions can trigger reconnection in the sheath of interplanetary coronal mass ejections (Feng & Wang, ) or in the Earth's magnetotail (Vörös et al, ).…”

Section: Introductionmentioning

confidence: 99%

MMS Observation of Magnetic Reconnection in the Turbulent Magnetosheath

et al. 2017

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In this paper we use the full armament of the MMS (Magnetospheric Multiscale) spacecraft to study magnetic reconnection in the turbulent magnetosheath downstream of a quasi‐parallel bow shock. Contrarily to the magnetopause and magnetotail cases, only a few observations of reconnection in the magnetosheath have been reported. The case study in this paper presents, for the first time, both fluid‐scale and kinetic‐scale signatures of an ongoing reconnection in the turbulent magnetosheath. The spacecraft are crossing the reconnection inflow and outflow regions and the ion diffusion region (IDR). Inside the reconnection outflows D shape ion distributions are observed. Inside the IDR mixing of ion populations, crescent‐like velocity distributions and ion accelerations are observed. One of the spacecraft skims the outer region of the electron diffusion region, where parallel electric fields, energy dissipation/conversion, electron pressure tensor agyrotropy, electron temperature anisotropy, and electron accelerations are observed. Some of the difficulties of the observations of magnetic reconnection in turbulent plasma are also outlined.

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Magnetic-reconnection exhausts in the sheath of magnetic clouds

Cited by 25 publications

References 37 publications

Superposed epoch study of ICME sub-structures near Earth and their effects on Galactic cosmic rays

Superposed epoch study of ICME sub-structures near Earth and their effects on Galactic cosmic rays

Coronal mass ejections and their sheath regions in interplanetary space

MMS Observation of Magnetic Reconnection in the Turbulent Magnetosheath

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