1. Observations of an Eruptive Flux Rope, CME Formation, and Associated Blast Wave
V.Grechnev1, A.Uralov1, I.Kuzmenko2, A.Kochanov1, V.Fainshtein1, Ya.Egorov1, D.Prosovetsky1
1Institute of Solar-Terrestrial Physics (Irkutsk, Russia)
2Ussuriysk Astrophysical Observatory (Ussuriysk, Russia)
SDO/AIA 193 Å
From Gopalswamy et al.: 2012, ApJ 744, 72

2. Major unanswered questions
2010 June 13 Event
A number of aspects were previously addressed by:
Patsourakos, Vourlidas, Stenborg: 2010, ApJL 724, L188
Kozarev et al.: 2011, ApJL 733, L25
Ma et al.: 2011, ApJ 738, 160
Gopalswamy et al.: 2012, ApJ 744, 72
Downs et al.: 2012, ApJ 750, 134
Eselevich & Eselevich: 2012, ApJ 761, 68
Vasanth et al.: 2014, Solar Phys. 289, 251
Kouloumvakos et al.: 2014, Solar Phys. 289, 2123, etc…
Genesis of the flux rope and its properties
How was the CME formed?
Where and how was the wave excited?
Major unanswered questions
- Common issues for many similar events

3. CME Lift-off in 171 Å. Outer boundary green
Looks mainly similar in 171, 193, 211, and 304 Å
a) Usual representation: fixed field of view
b) Resizing images to compensate for expansion
What drove the CME?

4. SDO/AIA 131 Å images Visible only Initial dark prominence2 3 4
Initial dark prominence
Prominence activates and brightens up  heating up to ~10 MK
Transforms into bundles of loops, which erupt
Rope expands, turns aside by 20, and rotates
Visible only
in 131 Å (10 MK) faint
in 94 Å (6.3 MK) still poorer

5. Flux rope in resized movie
Red arc outlines the top
Top: SDO/AIA 131 Å
Bottom: acceleration
Initial dark prominence
Brightens  heats
Transforms into bundles of loops, i.e., flux rope
Rope sharply erupts, 3 km/s2
Rope turns aside by 20, rotates, and decelerates,
-1 km/s2

6. Kinematics of the Flux Rope
Hot ~10 MK flux rope developed from structures initially associated with compact prominence
Flux rope appeared as a bundle of intertwisted loops
It sharply erupted with an acceleration up to  3 km/s2 1 min before HXR burst and earlier than any other structures,
reached a speed of 450 km/s
then decelerated to  70 km/s
Flare onset

7. CME development
193 Å
CME was driven by flux rope expanding inside it. Arcade loops above the rope
were sequentially involved into expansion from below upwards,
approached each other, and
apparently merged, constituting the visible rim
Flux rope rotated inside the rim, which has become an outer boundary of the cavity
Different event led Cheng et al. (2011, ApJL 732, L25) to similar conclusions

8. CME formation. Development of Rim
Images are resized to keep rim fixed
131 Å
171 Å

9. What was the Rim? The rim: red Below rim (304 & 171 Å): blue
40
LPS
304 Å
171 Å
211 Å
What was the Rim?
The rim: red
Below rim (304 & 171 Å): blue
Above rim (211 Å): green
different orientations: rim was associated with a separatrix surface
Not permeable, like a membrane
Expanding separatrix surface
swept up structures & plasmas ahead
left rarefied volume behind  dimming
Formation of rim: due to successive compression of structures above active region into CME’s frontal structure
When the rim was formed completely, it looked like a piston

10. Distance–Time History
-36
193 Å
Disturbance responsible for consecutive CME formation episodes
was excited by flux rope inside the rim
propagated outward
Structures at different heights accelerated, when their trajectories were crossed by trajectory of this disturbance
Flux rope transmitted part of its energy to structures above it
193 Å
arc sec
‘elastic collision’
Wave

11. Kinematics of Rope, Loops and Wave
Wave with v0  1000 km/s was excited by a subsonic piston, vP = 240 km/s
v0  1000 km/s is usual Alfvén speed above an active region
Acceleration of the piston was 3 km/s2 at that time
Impulsively excited wave decelerated like a blast wave

12. Type II burst
Method: Grechnev et al. (2011, Sol. Phys., 273, 433 & 461)
Wave signatures were leading portion of the EUV wave and type II radio burst
Also wave traces: onset of dm bursts recorded at fixed frequencies (white)
Outline: power-law density model and fit
Shock: see cited papers and talk by Fainshtein & Egorov

13. Eruption and Wave
AIA 211 Å base diff.
AIA 171 Å no subtraction

14. Plots of CME & Wave and LASCO data
Symbols: measurements from CME catalog
Lines: analytic fit
Main part of EUV transient became CME’s frontal structure (FS)
consisted of 1.8 MK coronal loops on top of the expanding rim
Wave strongly dampened and decayed into weak disturbance, being not driven by trailing piston, which slowed down

15. Conclusion…
Hot flux rope developed from structures associated with a compact prominence.
It sharply erupted earlier than any other structures and strongly accelerated. Then it decelerated, having transmitted a part of its energy to the CME structures above it. The relaxed flux rope became the CME core.
CME development was driven from inside by the expanding flux rope. Arcade loops above it were sequentially involved into expansion being compressed from below. They apparently approached each other, constituting the visible rim. The rim was separated from the active flux rope by a cavity. The rim was not pronounced in the white-light CME.
Contd…

16. …Conclusion
The rim was associated with an expanding separatrix surface. It swept up magnetoplasmas ahead, forming the main part of EUV transient (future CME frontal structure) and left rarefied volume behind, producing dimming.
The impulsively erupting flux rope produced inside the forming CME a disturbance, which propagated outward like a blast wave. Being not driven by the decelerating piston, it dampened and decayed into weak disturbance.
A number of events demonstrates a similar history of a wave. If a CME is fast, then such a blast-like wave should transform into bow shock afterwards.
Scenario of Hirayama (1974, Sol. Phys. 34, 323) appears to match the event.

17. Thanks For your attention
To organizers of this meeting for the opportunity to attend it and support
To the instrumental teams of SDO/AIA, SOHO (ESA & NASA), USAF RSTN, NICT (Japan), STEREO
To the team maintaining the SOHO/LASCO CME Catalog
To L. Kashapova and S. Anfinogentov for their assistance in data handling
To A. Kouloumvakos & co-authors for useful discussion