Coronal Dynamics - Can we detect MHD shocks and waves by Solar B ?

1. 2003 Feb. 3-5 Solar B Meeting @ ISAS Coronal Dynamics- Can we detect MHD shocks and waves by Solar B ? K. Shibata Kwasan Observatory Kyoto University

2. Introduction • Recent space observations such as Yohkoh, SOHO, TRACE have revealed various evidence of magnetic reconnection and common properties in flares/CMEs, leading to unified view of flares/CMEs. Impulsive flares Giant arcades (CMEs) LDE flares

3. Plasmoid (flux rope) ejections Unified model CMEs (Giant arcades) ~ 10^11 cm LDE flares ~ 10^10 cm impulsive flares ~ 10^9 cm

4. CDS spinning jet (Pike&Mason) Solar Jets • H alpha jets (surges) • EUV macrospicules • EIT jets • LASCO jets H alpha spinning jet (Kurokawa/Canfield) EIT-LASCO jet (Wang, Y. M.)

5. Unified model of flares and jets(Shibata 1999) (a,b)： LDE/impulsive flares and CME/plasmoid (c,d) ：microflares and jets

6. Unified model of flares and jets(Shibata 1999) Fast shock (a,b)： LDE/impulsive flares and CME/plasmoid (c,d) ：microflares and jets Slow shock Fast shock Alfven wave Should be tested by Solar B

7. Can we detect MHD shocks/waves by Solar B ?-- today’s talk : related new studies • Modeling of Peculiar Mass EjectionsAssociated with Giant Cusp Arcade- Fast and Slow Mode MHD Shocks are Identified !? Shiota et al. (2003) • Coronal Heating by Alfven Waves- nanoflare is not reconnection, but propagating MHD shocks !? Moriyasu et al. (2003) • Moreton wave => Narukageet al. (next talk)

8. Modeling of Peculiar Mass EjectionsAssociated with Giant Cusp Arcade- Fast and Slow Mode MHD Shocks are Identified !? Shiota et al. (2003)

9. Slow and Fast mode MHD shocks have not yet been identified • no clear evidence of slow and fast mode MHD shocks in SXT images Impulsive flares LDE flares

10. Giant Arcades are found at the base of Coronal Mass Ejections (Jan. 22-25, 1992) (April 14, 1994)

11. Giant Cusp Arcade and Peculiar Mass Ejection Jan 24, 1992 (Hiei, Hundhausen, & Sime 1993)

12. Ejection (Y-shaped structure) velocity30～40km/s

13. Simulations (Shiota et al. 2003; extention of Chen-Shibata model, including heat conduction) Normalization units

14. Predicted soft X-ray intensity （SXT/Al.1）

15. Y-shaped ejection

16. What is Y-shaped structure ? Y-shaped structure =Slow Shock ＆ Fast Shock

17. Observations : height-time diagram the center of Y-shape the top of cusp

18. Simulations : height-time diagram Triangle = Y-shaped structure = slow and fast shocks

19. Effect of Angle between arcade axis and line-of-sight Assume uniform arcade with length of 10^5 km SXT/Al.1 09:20 Angle=20° Angle=0° Angle=10° 0<DN/s<200 0<DN/s<50

20. XRT/Thin Al mesh SXT/Al.1 XRT/Al mesh Line-of-sight distance is 10^4 km

21. XRT/Thin Al poly SXT/Al.1 XRT/Al poly Line-of-sight distance is 10^4 km

22. XRT/Thin Ti poly SXT/Al.1 XRT/Ti poly Line-of-sight distance is 10^4 km

23. Intensity distribution XRT/Thin Al mesh Depth=10^5 km、angle=20° DN/s/pix pix exposure time Count=100 →10～15 sec

24. Coronal Heating by Alfven Waves- nanoflare is not reconnection, but propagating MHD shocks !? Moriyasu et al. (2003)

25. Motivation • Kudoh & Shibata (1999), Saitoh et al. (2001) successfully developed Alfven wave model of spicules and nonthermal line width in corona • Yokoyama (1998), Takeuchi & Shibata (2001)found that reconnection generate Aflven waves efficiently • SOHO revealed magnetic carpet, suggesting ubiquitous reconnection in the photosphere

26. Photospheric reconnection (or turbulent convection) => Alfven waves => coronal heating ? we performed the 1.5D-MHD numerical experiment including heat conduction and radiative cooling 100000km Initial condition T = 104 K = uniform photosphere based on 2D-MHD simulation of emerging flux Twist flux tube randomly （Shibata et al.1989) 1 km/s

27. Simulation Results (propagation of nonlinear Alfvén waves)

28. Simulation results (temperature distribution)

29. Temperature distribution

30. Heating mechanism Alfvén wave Nonlinear effect Compressional wave (slow mode & fast mode) shock formation Shock heating

31. Average coronal temperature vs photospheric velocity amplitude

32. “Observations” of simulation results Yohkoh/SXT => flare-like brightening SXT intensity is too low TRACE(EUV) intensity is comparable to observed intensity for 10^5 km coronal loop TRACE (171Å) 1998/6/4 TRACE (171Å)

33. Statistics of “flare” (shock heating) peak frequency distribution show power law ↓ intermittent heating due to MHD shocks generated by Alfvén waves might be observed as microflares or nanoflares ! Index:-1.6 ~ -2

34. Conclusion • Unified (reconnection) model of flares and jets predict generation of slow and fast mode MHD shocksas well as Alfven waves. • Slow and fast mode MHD shocks can be identified in Y-shaped mass ejection above giant cusp arcade (Shiota et al. 2003) • Spicules, nonthermal line width, and coronal heating are all explained by Alfven waves if its velocity amplitude > 1 km/s in the photosphere. (Kudoh-Shibata 1999, Saitoh et al. 2001) • Alfven waves can be dissipated through nonlinear mode coupling with fast and slow mode MHD waves/shocks. MHD shock heating is flare-like and might be observed as microflares or nanoflares(Moriyasu et al. 2003). => Should be tested by Solar B

36. fast shock & slow shock β<1 fast wave ：Va slow wave ：Cs in the present case, these are weak shocks fast shock ~ fast wave ~ Va slow shock ~ slow wave ~ Cs Va ~ 250 km/s Cs ~ 120 km/s

37. Alfven wave model of spicules:1.5D-MHD simulation (Kudoh-Shibata 1999)

38. 3. Are sufficient energy flux carried by Alfven waves into corona ?(Saitoh, Kudoh, Shibata 2001)

39. Energy flux transported to the coronaby Alfven waves Nonthermal Coronal Line width