TRACE and RHESSI observations of the failed eruption of the magnetic flux rope Tomasz Mrozek

1. TRACE and RHESSI observations of thefailederuption of themagneticfluxrope Tomasz Mrozek AstronomicalInstitute University of Wrocław

2. CSHKP („standard”) model Hirayama 1974 bipolarconfigurationisdestabilized-> raisingfilamentdragsarcade field lines -> magneticreconnectionoccursbelow thefilament -> thereclosedarcade and theflyingblobare the products of thisscenario Shibata et al., 1995

3. „standard” model Hyder, C. L. 1967 Basic problems: - thedarkfilamentexistsdue to sagging of the field lines atthetops of theconvexarcade - verystrong assumption Shibata et al., 1995

4. „standard” model Hirayama 1974 Basic problems: - thekinetic energy of theraisingfilamentshould be largerthanthe energy of theflareitself. Thus, in this model, theflareisonlythe repairingprocess of a moreenergetic break-upcaused by therisingfilament. Shibata et al., 1995

5. „standard” model Hirayama 1974 Basic problems: - observations show (Leroy et al. 1983)thatthedirection of magnetic field perpendicular to thefilamentisopposite to thedirectionexpectedfromthesimpleconnection of thebipolarfiledbelow Shibata et al., 1995

6. quadrupolar model 50 (!) years ago Sweet suggestedthatflares mayoccurinthequadrupolarmagneticfiled configuration. Thequadrupolar model describesobserved features of solarflaresin a more natural way. For somereasonthe theoretical work has ignored this kind of complexity and try to developthetheory of simple, bipolarconfiguration – the „standard” model Fortunately, thetheory of Sweet hasbeen ressurectedrecently. Sweet, P. A. 1958

7. quadrupolar model In this model theexistence of thedark filamentisobvious. Moreover, iteasily explainstheobservedverythinvertical structure of thefilament The energy isbuiltupinthe system beforethedarkfilamenteruption Thedarkfilamentisacceleratedupward, and inthelower region recconnected field lines shrink to form magnetic arcade A quotationfromHirose et al. (2001): In thissimulation (…) theupwardmotion of thedarkfilament (…) mayeventually be arrested by theoverlyingclosed field. Uchida et al. 1999 Hirose et al. 2001

8. theflare July 14th, 2004 M6.2 GOES class N14 W61 Observations RHESSI: entireevent TRACE: 171 Å (severalseconds cadence)

9. observatories TRACE (1998) 30 cm Cassegraintelescopegiving 1 arcsec spatial resolution Theobservationsaremadeinthe EUV (transition region, colonalloops) and UV (chromosphere) ranges. Moreover, white-lightimagesaremade RHESSI (2002) 9 large, germaniumdetectors observationsaremadeintherange from 3 keV to 17 Mevwith high energy resolution spatial resolution isup to 2.5 arc sec

10. theflare • Relativelystrongflareisconnectedwith • smallmagneticarcade (less than 104km). • Severalepisodeswereobserved: • - brighteningsbeforetheflare • eruptionwhich was startedduringtheimpulsivephase • deceleration of theeruption and sideeruptions • radialoscillations of the system of loopsobserved high inthecorona

11. preflareactivity Preflarebrighteningswereobserved between 5:03 and 5:17 UT. In the TRACE imageswe observed brighteningsinsmallsystems of loops Thereisenoughsignal for reconstructing RHESSI imageswithdetector 1 giving thehighestspatial resolution (about 2.5 arc sec)

12. preflareactivity Contours – RHESSI sources observedintherange 8-16 keV

13. thebeginnig of theimpulsivephase Abruptbrighteningconnectedwiththeflareisvisible on the TRACE imageobtained on 5:17:30 UT Theeruption of themagneticfluxtubeisobserved severalsecondsafter Theeruptionstartedin a very compact region (about 3000 km indiameter!)

14. theeruption Theheight of theeruptingstructure was calculatedalongtheyellowline. On each TRACE imagethedistance betweenthe front of theeruption and thereferenceline was calculated

15. evolution of theeruption Initialphase, theeruption moveswith small, constant velocity 3 H[km] 2 1 Fast evolution followingthe strongest HXR peakvisible in 25-50 keV range 25-50 keV Deceleration phase. Main front changes itsshape. Side eruptionsare observed

16. interactionwithlow-lyingloops Thedecelerationvalue (about 600 m/s2) and theshape of theeruption front show that „something”stoppedit. Itispossiblethattwo systems of loopswereinvolvedinbrakingtheeruption. Brighteningsobservedduringthedeceleration of themain front.

17. interactionwithlow-lyingloops Brighteningsinthe region markedwith the red boxsuggesttheinteraction betweentheeruption and surrounding magneticstructures

18. interactionwithlow-lyingloops Theshape of theeruptionsuggeststhatthereis a low-lying (but stillabovetheflare) system of loopsexistingduringtheimpulsivephase. Moreover, therearebrighteningsobservedin the same locationwherelow-lying system of loopsisanchored. Possiblytheloopswhere heateddue to interactionwiththeeruption – theyare not „post-flareloops” within themeaning of the standard model

19. interactionwithlow-lyingloops We observedthe 8-16 keVsourcelocatedinthe region of possibleinteractionbetween theeruption and thelow-lyingloops

20. interactionwithhigh-lyingloops Abovetheerupting structure we observed the system of high-lying loops. Theseloopschanged theirheight as the eruptionevolved.

21. interactionwithhigh-lyingloops Theend of theforemosteruption (and theend of theforcedrivingthe movement of thehigh-lyingloops) Thebeginning of the northern eruption High-lyingloopsstarted to rise

22. theevolution of thehigh-lyingloops theend of theforcedrivingthe movement of thehigh-lyingloops loopsstarted to move back

23. global oscillations of coronalloops Tangential, horizontal No change of radius About 20 observationsreported by severalauthors Radial, transversal Change of radius One observation (Wang & Solanki 2004) We observedradialoscillations of coronalloops – veryrareevent. In ourcase we saw „thefinger” thatpulledloops – themagneticstructureejectedfrombelowtheseloops

24. theevolution of thehigh-lyingloops

25. summary –smallbrighteningsobservedbeforetheflarewithintheflaringstructure  – brighteningsoutsidetheflaringstructureduringtheinteractionbetweentheeruption and surroundingloops – deceleration of theeruptioncaused by theexistence of surrounding system of loops  – theeruptionstartedin a very compact region, not inthelarge system of loops

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28. summary