Coronal hard X-rays prior to RHESSI

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Coronal hard X-rays prior to RHESSI

• H. S. Hudson
• Space Sciences Lab, UC Berkeley

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Coronal hard X-rays prior to RHESSI
Yohkoh

• H. S. Hudson
• Space Sciences Lab, UC Berkeley

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Outline

• Review of metric radio morphology and physics
• The extended flare (Frost Dennis, OSO-7,
  Kiplinger, Cliver et al.)
• Some Yohkoh coronal observations - cf Tomczak
  Masuda presentations
• Comments about the physics

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The solar corona
Sunspot cycle maximum
Sunspot cycle minimum
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Schrijver-DeRosa PFSS example
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Distribution of coronal plasma b
CH
G. A. Gary, Solar Phys. 203, 71 (2001)
(vA 200 b-1/2 km/s)
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Overview of metric solar burst phenomenology,
courtesy Hiraiso Observatory
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Coronal radio emission at metric wavelengths

• Type I noise storm Not well understood?
• Type II slow drift burst Large-scale shock
  wave
• Type III fast drift burst Electron beam
• Type IV extended flare Relativistic electrons
• Type V Electron beam
• U-burst Electron beam

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Coronal hard X-ray sources

• March 30, 1969 event (Frost Dennis, 1971)
• Two OSO-7 events (Hudson 1978, Hudson et al.
  1982)
• Review paper (Cliver et al. 1986) including
  front-side events
• Hard X-rays and protons (Kiplinger, 1995)
• Yohkoh observations (cf. Masuda, Tomczak)
• An omission from this talk HXIS

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Frost Dennis 1971
March 30, 1969 X-rays and Microwaves
No Ha flare, W105
Enome Tanaka 1971 (3.5 GHz)
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March 30, 1969 meter waves (Culgoora)
Palmer Smerd, 1972
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OSO-7 event of Dec. 14, 1971
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OSO-7 event of July 22, 1972
X-rays
Electrons
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May 13, 1981 - a unique Hinotori event, _at_ 6.6 x
104 km
Loughhead et al. 1983
Tsuneta et al. 1984
Kawabata et al. 1983
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Over-the-limb events by 1986
Hudson, 1986
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Kane 1983 PVO ISEE-3
stereo observations!
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Kane 1983 PVO ISEE-3
stereo observations!
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Kane 1983 PVO ISEE-3
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Cliver et al. 1986
gradual HXR events
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Cliver et al. 1986
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Cliver cartoon
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Cliver et al. 1986
Some disagreement regarding microwave-richness?
Kiplinger, 1995
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Hard X-ray association with SEPs
Squares gt solar proton events Filled squares gt
progressive hardening
Kiplinger, ApJ 453, 973 (1995)
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Yohkoh contributions

• A decade of observations with both soft and hard
  X-ray imaging
• What are the (hard) X-ray counterparts of the
  metric phenomenology?
• What do hard X-ray images of extended flares look
  like?
• cf. Masuda and Tomczak presentations

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Metric burst-type scorecard

• Type I - observed soft X-rays from magnetic cusp
  (streamer) regions?
• Type II - observed soft X-rays from blast waves
• Type III - identified channels with soft X-ray
  jet trajectories
• Type IV - observed hard X-rays from moving
  source?
• Type V - ??
• U-burst - identified channels with soft X-ray jet
  trajectories

Not much hard X-ray progress?
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Soft X-rays from blast waves
Hudson et al. 2003
Khan Aurass 2002
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Hard X-rays from ejecta
Hudson et al. 2001
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The 2001 April 18 event

• A large fast-moving hard X-ray source appeared
  above the limb, in association with a 17-GHz
  microwave source
• Association with m-wave phenomenology is
  problematic, but there was a type-II-like event
• Interpretation suggests a plasmoid (expanding
  loop) in which nonthermal pressure may dominate
  (??)
• Unique Yohkoh event in the middle corona?

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Conclusions

• Pre-RHESSI observations, both direct and
  limb-occulted, showed a wide variety of coronal
  hard X-ray emissions
• The coronal sources could be associated with
  various metric burst types, or not (eg., May 13,
  1981)
• Some of the coronal sources showed exceptionally
  flat hard X-ray spectra there is a pattern of
  gradual hardening
• The most interesting sources are probably the
  ones distinct from the loop-top soft X-ray
  sources, ie non-thermal in nature

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Particles in the PFSS context

• Elliott proposal
• Fields and particles compared
• Sources of particles
• Stability issues
• Convenience of Schrijver-DeRosa software
• Suitability of PFSS modeling

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Proposal for a review paper

• The March 30, 1969 event was somewhat analogous
  to the Carrington event - ausgezeichnet
• There was copious literature, at the time, but no
  synthesis
• Thanks to this workshop, we will know a lot
  more about the processes involved
• Would a review of this single event, based on
  secondary sources be worthwhile? Or should it
  just be a part of the main overview paper?
• Another possible single-event paper would be the
  May 13 1981 event, but I think it is less
  representative