Coronal hard X-rays prior to RHESSI

Coronal hard X-rays prior to RHESSI

H. S. Hudson

Space Sciences Lab, UC Berkeley

Coronal hard X-rays prior to RHESSI

H. S. Hudson

Space Sciences Lab, UC Berkeley

Yohkoh

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

ISSI, October 2, 2006

QuickTime™ and aTIFF (Uncompressed) decompressor

are needed to see this picture.

Sunspot cycle maximum Sunspot cycle minimum

The solar corona


Schrijver-DeRosa PFSS example


G. A. Gary, Solar Phys. 203, 71 (2001)

(vA ~ 200 -1/2 km/s)

CH

Distribution of coronal plasma


Overview of metric solar burst phenomenology, courtesy Hiraiso Observatory


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• …


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


Frost & Dennis 1971

Enome & Tanaka 1971(3.5 GHz)

March 30, 1969:X-rays and Microwaves

No H flare, ~W105


Palmer & Smerd, 1972

March 30, 1969: meter waves (Culgoora)


OSO-7 event of Dec. 14, 1971


X-rays

Electrons

OSO-7 event ofJuly 22, 1972


May 13, 1981 - a unique Hinotori event, @ 6.6 x 104 km

Loughhead et al. 1983Tsuneta et al. 1984

Kawabata et al. 1983


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Over-the-limb events by 1986

Hudson, 1986


Kane 1983: PVO & ISEE-3 stereo observations!


Kane 1983: PVO & ISEE-3


Cliver et al. 1986gradual HXR events


Cliver et al. 1986


Cliver cartoon


Some disagreement regardingmicrowave-richness? Kiplinger, 1995

Cliver et al. 1986


Hard X-ray association with SEPs

Kiplinger, ApJ 453, 973 (1995)

Squares => solar proton eventsFilled squares => progressive hardening


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


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?


Soft X-rays from blast waves

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Hudson et al. 2003

Khan & Aurass 2002


Hard X-rays from ejecta

Hudson et al. 2001


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?


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


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


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

Coronal hard X-rays prior to RHESSI

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