2. IGPP, March 3 2005 Coronal shock waves observed in images H.S. Hudson SSL/UCB

3. IGPP, March 3 2005 Outline How coronal imaging should help with understanding shock waves Origins of large-scale coronal waves Mach numbers

4. IGPP, March 3 2005 Conclusions Large-scale coronal waves originate in compact magnetic structures The Mach numbers in the corona are low We can’t yet image the CME flow field in the corona (ie, below coronagraph occulting edges)

5. IGPP, March 3 2005 What coronal shocks should look like… Korreck et al., 2004

6. IGPP, March 3 2005 Chandra E0102-72

7. IGPP, March 3 2005 Imaging of coronal shocks: good news and bad news A shock wave should provide a sharp density gradient, easy to detect in images We can observe motions in two dimensions The medium is optically thin => confusion The wave may not be bright compared with other flare components The corona generally has low plasma beta, so the observed mass may not be structurally important

8. IGPP, March 3 2005 … Only imaging can properly characterize the large-scale structure The solar corona isn’t really accessible any other way

9. IGPP, March 3 2005 Imaging of coronal shocks Type II bursts (plasma radiation) Moreton waves (H  in the chromosphere) New modalities: EIT, X-rays 1, microwaves, meter waves, He 10830 1 Three events: Khan & Aurass (2002); Narukage et al. (2002); Hudson et al. (2003)

10. IGPP, March 3 2005 Type II burst

11. IGPP, March 3 2005 Moreton-Ramsey wave and EIT wave Thompson et al., 1998

12. IGPP, March 3 2005 G. A. Gary, Solar Phys. 203, 71 (2001) CH Mann et al., A&A 400, 329 (2003) Gopalswamy et al., JGR 106, 25251 (2001) (v A ~ 200  -1/2 km/s ?)

13. IGPP, March 3 2005 Direct X-ray observation Uchida 1968 Yohkoh 1998 EIT

14. IGPP, March 3 2005 Why X-ray waves are hard to observe directly

15. IGPP, March 3 2005 Field and energy are concentrated in active regions Active-region magnetic fields via Roumeliotis-Wheatland technique (McTiernan) Mass loading via empirical law (Lundquist/Fisher)

16. IGPP, March 3 2005 Lundquist et al., SPD 2004

17. IGPP, March 3 2005 NOAA 10486, Haleakala IVM data,  cube Roumeliotis-Wheatland-McTiernan method pixel size ~3000 km ScaledNot scaled

18. IGPP, March 3 2005 Heliospheric shocks in images? Maia et al., ApJ 528, L49 (2000) Vourlidas et al., ApJ 598, 1392 (2003) SOHO/UVCS

19. IGPP, March 3 2005 Vourlidas et al., ApJ 598, 1392 (2003) Where is the bow shock ?

20. IGPP, March 3 2005 Inferring the Mach number

21. IGPP, March 3 2005 X-ray signal S ~ n e 2 f(T) f(T) ~ T 2 d(ln(S))/d(ln(n)) ~ 2  Mach number estimate for 6 May 1998 event

22. IGPP, March 3 2005 Movie of dimming (Aug 28, 1992) Coronal Dimming

23. IGPP, March 3 2005 Dimming observed spectroscopically Harra & Sterling, ApJ 561, L216, 2001

24. IGPP, March 3 2005 UVCS shock observations Raouafi et al., A&A 434, 1039, 2004 Mancuso et al., A&A 383, 267, 2002 Raymond et al., GRL 27, 1439, 2000

25. IGPP, March 3 2005 Cartoon illustrating wave origins cf. http://solarmuri.ssl.berkeley.edu/~hhudson/cartoons

26. IGPP, March 3 2005 The CME-driven shock in the corona The CME involves outward plasma motions perpendicular to the field We see the result of these motions as dimmings, but the data are not good enough to follow the flows nor to see a bow wave There is an Alfven-speed “hole” in the middle corona in which Mach numbers could be larger

27. IGPP, March 3 2005 SUMMARY Coronal shock waves (metric type II) are blast waves (Uchida) launched by compact structures at flare onset. These propagate in an undisturbed corona The CME eruption restructures the corona and pushes a bow wave ahead of it into the solar wind. This creates a type II burst at long wavelengths

28. IGPP, March 3 2005 Conclusions Large-scale coronal waves originate in compact magnetic structures The Mach numbers in the corona are low We can’t yet image the CME flow field in the corona (ie, below coronagraph occulting edges)

29. IGPP, March 3 2005 END

30. IGPP, March 3 2005 Flare and CME energy partition