talk from egu (2015)
TRANSCRIPT
3D Evolution of fast and slow CMEs from the Sun to 1 AU
Alexey Isavnin, Sebastian Käki, Emilia Kilpua
Department of Physics, University of Helsinki, Finland 2015
Outline
• Observations and techniques • Assumptions and limitations • Previous results for average-speed CMEs • Evolution of slow and fast CMEs
3D evolution of CMEs: Observations
EUV observations
coronagraph observations
heliospheric imaging
in-situ observations
Sun 5 Rs 30 Rs 1 AU
3D evolution of CMEs: Techniques
CME source & post-eruptive arcades è direction & orientation
FM è direction & orientation
Fixed-Φ, HM or SSE è only direction
GSR or other FR fitting models è only local orientation
Sun 5 Rs 30 Rs 1 AU
Möstl et al., 2014
3D evolution of CMEs: Techniques
last orientation from FM local orientation as a constraint for global orientation
30 Rs 1 AU
MHD-simulated background solar wind (MAS model)
è è
Assumptions and limitations • CME has a flux rope inside, i.e. FR-CME is considered • FR-CME is described by GCS model
• CME evolution is composed of deflections, rotations and self-similar expansion
Assumptions and limitations • Interaction between CME and background solar wind is
purely kinematic
• The pattern of background solar wind does not change during one Currington rotation
Summary of previous results • 14 average-speed FR-CMEs observed between 2008 and
2010 were analyzed (Isavnin et al., 2013, 2014) • The FR-CMEs were found to get approximately aligned
with HCS • The FR-CMEs were found to experience 60% of
geometrical evolution (deflections and rotation) in the lower corona, i.e., during the first 30 Rs of propagation.
Evolution of slow and fast CMEs Slow Fast
28 February 2010 Vr = 300 km/s in the lower corona a = 5.9 m/s2 at 20 Rs Vr = 355 km/s at 1 AU
1 October 2011 Vr = 1238 km/s in the lower corona a = --10.1 m/s2 at 20 Rs Vr = 683 km/s at 1 AU
Conclusions • 3D evolution of slow and fast CMEs from the Sun to 1 AU was
analyzed. • The fast CME experienced most of deflection (75% longitudinal,
94% latitudinal) in the lower corona. • The slow CME experienced substantial fraction of deflection
(64% longitudinal, 39% latitudinal) in the inner heliosphere. • Both fast and slow CMEs experienced the majority of rotation
(92%) in the lower corona. • The magnitudes of deflections and rotations fall within ranges of
the previously studied events in Isavnin et al., 2013, 2014.