White-Light Flares: TRACE and RHESSI Observations
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Transcript of White-Light Flares: TRACE and RHESSI Observations
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White-Light Flares: TRACE and RHESSI
Observations
H. Hudson (UCB), J. Wolfson (LMSAL)
& T. Metcalf (CORA)
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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, at least in part, 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
• Solar-B should be able to make wonderful observations of WLF
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Event Selection
• 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
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TRACE spectralResponse
Solar-cycle modulation(Lean, 1997)
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Event Lista
aHudson et al., Solar Phys. (in press, 2005)
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2002 Oct. 405:35:49 UT
2002 Oct. 510:41:58 UT
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WL versus UV (1700A)
TRACE WL WL difference 1700 A
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Intermittency
32 x 68 arc s frames
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WL-1700A Comparison
Reversed colors!
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WL-hard X-ray comparison
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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