1. White-Light Flares via TRACE and RHESSI: Death to the thick target? H. Hudson, plus collaboration with J. Allred, I. Hannah, L. Fletcher, T. Metcalf, J. Wolfson

2. White-Light Flares (WLF) “White light” is formed deep in the solar atmosphere and is therefore energetically important (also note “white-light prominences,” which are up in the corona) White-light (and UV) continuum emission associates well with the hard X-ray impulsive phase (Neidig) There are some WLF observations from space prior to TRACE (Yohkoh; Matthews et al., 2003), but TRACE and RHESSI give us much better data

3. Wolfson sample TRACE catalog => events with <10 s cadence in white light and full resolution, GOES C and above, full RHESSI coverage Total event list consists of 33 events during RHESSI operations through 2004 11 events (X: 0; M: 7; C: 4) All 11 events have TRACE WL response All 11 events have RHESSI hard X-ray response 10/11 events appear to be largely footpoints; one has obvious coronal sources as well

4. 13:40 PST Jan. 18 TRACE spectral response: “WL” & 1700 ratio Solar-cycle modulation (Lean, 1997)

5. 13:40 PST Jan. 18 2002 Oct. 4 05:35:49 UT 2002 Oct. 5 10:41:58 UT

6. 13:40 PST Jan. 18 Intermittency 32 x 68 arc s frames

7. 13:40 PST Jan. 18 WL-hard X-ray comparison

8. 13:40 PST Jan. 18 RHESSI/TRACE/MDI overlay

9. 13:40 PST Jan. 18 RHESSI/TRACE/MDI overlay, illustrating MDI roll problem

10. 13:40 PST Jan. 18

11. Conclusions WL emission, as seen by TRACE, is not resolved at angular resolution 1”, temporal resolution 10 s The data confirm a strong association with hard X-rays Sources may be extended in area and include loop tops “True” WL is morphologically different from UV TRACE WL contrasts can exceed 100% even for flares below X class

12. 13:40 PST Jan. 18 Next steps WLF/HXR morphology: how good is the match? Energetics: what can we learn about HXR cutoff energy? Theory: how can such intense energy release be reconciled with coronal particle acceleration?

13. 13:40 PST Jan. 18 Miscellaneous other related slides

14. TRACE The TRACE white light channel has significant contributions from 1700 Å to 1  m, 0.5” pixels UV contributions to the white light channel can be reduced by subtracting the TRACE 1700 channel RHESSI Energy range 3 keV - 15 MeV, resolution (FWHM) ~ 1 keV Time resolution 4 sec without image deconvolution

15. 13:40 PST Jan. 18 2004 Jan. 9 01:40:17 UT 2003 June 12 01:27:01 UT

16. 13:40 PST Jan. 18 2002 Nov. 2 18:16:04 UT 2004 July 22 00:29:56 UT

17. 13:40 PST Jan. 18 2003 Oct. 23 02:39:49 UT 2002 July 25 03:59:04 UT

18. 13:40 PST Jan. 18 2002 July 26 19:00:25 UT 2004 July 24 13:34:38 UT

19. 13:40 PST Jan. 18 Loop-top WL emission (“WL prominence”) Event of 2002 Nov. 12, 17:58 UT

20. 13:40 PST Jan. 18 Statistical Properties of fixed differences

21. 13:40 PST Jan. 18

22. WL versus UV (1700A) TRACE WLWL difference1700 A

23. 13:40 PST Jan. 18 WL-1700A Comparison Reversed colors!