Talk from EGU (2015)

1. 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

2. Outline
• Observations and techniques
• Assumptions and limitations
• Previous results for average-speed CMEs
• Evolution of slow and fast CMEs

3. 3D evolution of CMEs: Observations
EUV
observations
coronagraph
observations
heliospheric
imaging
in-situ
observations
Sun 5 Rs 30 Rs 1 AU

4. 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

5. 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

6. 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

7. 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

8. 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.

9. 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

10. Longitudinal deflection
slow
fast

11. Longitudinal deflection
1—-30 Rs
30--215 Rs
slow fast
slow fast

12. Latitudinal deflection
1—-30 Rs
30--215 Rs
slow fast
slow fast

13. Rotation
1—-30 Rs
30--215 Rs
slow fast
slow fast

14. Interaction with background SW
Slow Fast

15. 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.