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) 2010-06-13 SDO/AIA 193 Å From Gopalswamy et al.: 2012, ApJ 744, 72

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

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?

SDO/AIA 131 Å images Visible only Initial dark prominence 2 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

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

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

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

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

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

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

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

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

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

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

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…

…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.

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