Solar Wind and Heavy Ion Properties of Interplanetary Coronal Mass Ejections

Abstract

Magnetic field and plasma properties of the solar wind measured in near-Earth space are a convolution of coronal source conditions and in-transit processes which take place between the corona and near-Earth space. Elemental composition and heavy ion charge states, however, are not significantly altered during transit to Earth and thus such properties can be used to diagnose the coronal source conditions of the solar wind observed in situ. We use data from the Advanced Composition Explorer (ACE) spacecraft to statistically quantify differences in the coronal source properties of interplanetary coronal mass ejections (ICMEs). Magnetic clouds, ICMEs which contain a magnetic flux-rope signature, display heavy ion properties consistent with significantly hotter coronal source regions than noncloud ICMEs. Specifically, magnetic clouds display significantly elevated ion charge states, suggesting they receive greater heating in the low corona. Further dividing ICMEs by speed, however, shows this effect is primarily limited to fast magnetic clouds and that in terms of heavy ion properties, slow magnetic clouds are far more similar to non-cloud ICMEs. As such, fast magnetic clouds appear distinct from other ICME types in terms of both ion charge states and elemental composition. ICME speed, rather ICME type, correlates with helium abundance and iron charge state, consistent with fast ICMEs being heated through the more extended corona. Fast ICMEs also tend to be embedded within faster ambient solar wind than slow ICMEs, though this could be partly the result of in-transit drag effects. These signatures are discussed in terms of spatial sampling of ICMEs and from fundamentally different coronal formation and release processes.

Solar Cycle Dependence of ICME Composition

“…The statistical results based on fewer events should not be credible, so we do not further divide the yearly ICMEs into fast and slow ones, or magnetic clouds and non-cloud events (Owens, 2018). There were only a few events in 2007 and 2008, while 29 events in total were detected during the solar minimum (2006)(2007)(2008)(2009).…”

“…This does not support that the filament plasma originates from the corona. Owens (2018) analyzed the charge states of C, O, and Fe within 215 ICMEs, including 97 magnetic clouds and 118 non-cloud events. The work reported that magnetic clouds exhibit higher ionic charge states than non-magnetic clouds.…”

“…The work reported that magnetic clouds exhibit higher ionic charge states than non-magnetic clouds. In addition, statistical results demonstrated that fast magnetic clouds have higher charge states and relative elemental abundances (except the C/O) than slow ones (Owens, 2018;Huang et al, 2020), and cold prominence plasmas with lower charge states can be detected within ICMEs near 1 au (Lepri and Zurbuchen, 2010;Gilbert et al, 2012;Sharma and Srivastava, 2012;Wang, Feng, and Zhao, 2018;Feng et al, 2018). Zurbuchen et al (2016) performed a comprehensive analysis of the elemental abundances of 310 ICMEs on Richardson and Cane's catalog from 1998 March to 2011 August (Richardson and Cane, 2010).…”

Magnetic Structure and Propagation of Two Interacting CMEs From the Sun to Saturn

“…The properties of interplanetary CMEs (or ICMEs; e.g., Kilpua et al, 2017) have been studied mainly around 1 AU (e.g., Cane & Richardson, 2003;Jian et al, 2006Jian et al, , 2018Nieves-Chinchilla et al, 2019;Owens, 2018;Regnault et al, 2020;I. G. Richardson & Cane, 2010), that is where continuous in-situ measurements of the solar wind have been available for several decades and up to this day.…”

The Inhomogeneity of Composition Along the Magnetic Cloud Axis

“…Huang et al [47] analyzed the composition inside 124 MCs and reported that fast MCs have higher charge states and relative elemental abundances (except the C/O) than slow ones. Owens [48] analyzed the charge states of carbon, oxygen, and iron within 215 ICMEs, including 97 MCs and 118 non-cloud events, and found that MCs exhibit higher ionic charge states than non-cloud events. Zurbuchen et al [49] performed a comprehensive analysis of the elemental abundances of 310 ICMEs from 1998 March to 2011 August.…”