Talk from EGU (2015)

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

Longitudinal deflection

slow fast

Longitudinal deflection

1—-30 Rs 30--215 Rs

slow fast

slow fast

Latitudinal deflection

1—-30 Rs 30--215 Rs

slow fast

slow fast

Rotation

1—-30 Rs 30--215 Rs

slow fast

slow fast

Interaction with background SW Slow Fast

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.