Abstract
Interplanetary coronal mass ejections (ICMEs) observed by the MESSENGER (MES) and Venus Express (VEX) spacecraft have been catalogued and analysed. The ICMEs were identified by a relatively smooth rotation of the magnetic field direction consistent with a flux rope structure, coinciding with a relatively enhanced magnetic field strength. A total of 35 ICMEs were found in the surveyed MES data (primarily from March 2007 to April 2012), and 84 ICMEs in the surveyed VEX data (from May 2006 to December 2013). The ICME flux rope configurations have been determined. Ropes with northward leading edges were about four times more common than ropes with southward leading edges, in agreement with a previously established solar cycle dependence. Ropes with low inclinations to the solar equatorial plane were about four times more common than ropes with high inclinations, possibly an observational effect. Left and right-handed ropes were observed in almost equal numbers. In addition, data from MES, VEX, STEREO-A, STEREO-B and ACE were examined for multipoint signatures of the catalogued ICMEs. For spacecraft separations below 15{\deg} in heliocentric longitude, the second spacecraft observed the ICME flux rope in 82% of cases; this percentage dropped to 49% for separations between 15 and 30{\deg}, to 18% for separations between 30 and 45{\deg}, and to 12% for separations between 45 and 60{\deg}. As spacecraft separation increased, it became increasingly likely that only the sheath and not the flux rope of the ICME was observed, in agreement with the notion that ICME flux ropes are smaller in longitudinal extent than the shocks or discontinuities that they often drive. Furthermore, this study has identified 23 ICMEs observed by pairs of spacecraft close to radial alignment. A detailed analysis of these events could lead to a better understanding of how ICMEs evolve during propagation.
Highlights
Coronal mass ejections (CMEs) are large-scale eruptions of magnetic flux, helicity and plasma from the Sun distinct from the continuous outflow of the solar wind
We present a catalogue of Interplanetary coronal mass ejections (ICMEs) observed by the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER; MES) spacecraft, and by Venus Express (VEX)
Magnetometer data from the MESSENGER and Venus Express spacecraft have been examined for the signatures of ICMEs
Summary
Coronal mass ejections (CMEs) are large-scale eruptions of magnetic flux, helicity and plasma from the Sun distinct from the continuous outflow of the solar wind Their interplanetary manifestations, ICMEs, display a range of signatures when observed by spacecraft in situ (Zurbuchen and Richardson, 2006). We present a catalogue of ICMEs observed by the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER; MES) spacecraft, and by Venus Express (VEX). This analysis has been used to estimate the probability that two spacecraft will observe the same ICME as a function of the spacecraft’s heliocentric longitudinal separation This analysis will be useful for those seeking to perform studies of ICMEs observed by radially aligned spacecraft involving MES or VEX, or studies that consider longitudinal variations in ICMEs. Other ICME catalogues have recently been compiled that use MESSENGER and Venus Express data.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have