Quantitative Analysis of CME Deflections in the Corona

Abstract

In this paper, ten CME events viewed by the STEREO twin spacecraft are analyzed to study the deflections of CMEs during their propagation in the corona. Based on the three-dimensional information of the CMEs derived by the graduated cylindrical shell (GCS) model [Thernisien et al., 2006], it is found that the propagation directions of eight CMEs had changed. By applying the theoretical method proposed by Shen et al. [2011] to all the CMEs, we found that the deflections are consistent, in strength and direction, with the gradient of the magnetic energy density. There is a positive correlation between the deflection rate and the strength of the magnetic energy density gradient and a weak anti-correlation between the deflection rate and the CME speed. Our results suggest that the deflections of CMEs are mainly controlled by the background magnetic field and can be quantitatively described by the magnetic energy density gradient (MEDG) model.Comment: 19 pages, 20 figure

The Physical Processes of CME/ICME Evolution

“…Flux ropes ejected from the solar corona during CMEs may travel through interplanetary space largely intact, and careful examination suggests that they can be connected to the magnetic structures observed at 1 AU (e.g., Yurchyshyn et al 2007;Démoulin 2008;Möstl et al 2008;Liu et al 2010aLiu et al ,b, 2011Howard and DeForest 2012;Manchester et al 2014a;. The magnetic fields associated with ICMEs often retain a coherent structure resembling a flux rope.…”

“…In this case, what is seen by a spacecraft is the segment tangent to the line of sight. The triangulation concept has proven to be a useful tool for determining CME Sun-to-Earth kinematics and connecting imaging observations with in situ signatures (e.g., Liu et al 2010aLiu et al ,b, 2011Mishra and Srivastava 2013). Details of when, where, and how CMEs accelerate/decelerate in interplanetary space can be quantified using the kinematics derived with the triangulation method.…”

Short-term variability of the Sun-Earth system: an overview of progress made during the CAWSES-II period

“…Defining the background is one of the key inputs needed for understanding CME propagation (see e.g., Roussev et al 2012;Arge et al 2013). However, there are other processes that can significantly affect the propagation of CMEs: CME-CME interaction (see e.g., Gopalswamy et al 2001a;2012c;Temmer et al 2012;Harrison et al 2012;Lugaz et al 2012;Liu et al 2014a;Sterling et al 2014;Temmer et al 2014) and CME deflection by largescale structures such as coronal holes and streamers (Gopalswamy 2010(Gopalswamy , 2009dShen et al 2011;Gui et al 2011;Wood et al 2012;Kay et al 2013;Panasenco et al 2013;Gopalswamy and Mäkelä 2014).…”

“…In the declining phase, low-latitude coronal holes appear frequently, so CME deflection by such coronal holes becomes important (Gopalswamy et al 2009d;Mohamed et al 2012;Mäkelä et al 2013). The deflections are thought to be caused by the magnetic pressure gradient between the eruption region and the coronal hole (Gopalswamy et al 2010d;Shen et al 2011;Gui et al 2011).…”

Solar activity and its evolution across the corona: recent advances

“…Basic characteristics of the candidate source regions, like heliographic coordinates and neutral line tilt, were contrasted to the CMEs direction of propagation, main symmetry axis orientation, and general three-dimensional morphology. In all of the analyzed cases, significant deflections were found, not only in the latitudinal direction, but also in the usually unexplored longitudinal one (see Gui et al 2011;and references herein). The performed morphological analysis revealed that the CMEs main axis orientations are in general accordance with their associated source region tilts.…”