PTA, September 21, 2005 Solar flares in the new millennium H.S. Hudson Space Sciences Lab, UC Berkeley.

PTA, September 21, 2005

Solar flares in the new millennium

H.S. Hudson

Space Sciences Lab, UC Berkeley

PTA, September 21, 2005

Solar flares since 1991

H.S. Hudson

Space Sciences Lab, UC Berkeley

PTA, September 21, 2005

Solar physics is no longer the only branch of astrophysicsin which movies can be considered to be data…

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PTA, September 21, 2005

Schema (inspired by R. Genzel)

• Object: Galactic Center• Astronomer’s view:

Black hole! • Astrophysicist’s view:

We can learn about relativity, gravity, etc in a new environment!

• Object: Solar Flare• Astronomer’s view:

Magnetic reconnection!• Astrophysicist’s view:

We can learn about plasma behavior in a new environment!

PTA, September 21, 2005

What is the solar corona?

• Low-beta plasma in a concentric cavity• Slowly-varying lower boundary condition

imposing vertical currents• Body currents (and current sheets) in an

isopotential volume• Massive solar wind forming a lumpy upper

boundary• Flaring (flares and CMEs)

PTA, September 21, 2005

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

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

CH

Distribution of coronal plasma

PTA, September 21, 2005

Yohkoh, RHESSI, TRACEand ground-based data:

Recent wonders and marvels

PTA, September 21, 2005

Movie of dimming (Aug 28, 1992)

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Coronal Dimming

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PTA, September 21, 2005

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TRACE 1600A

TRACE 171A

Shrinkage, dimming, destruction, oscillation

Helix, ribbons (separatrices?)

PTA, September 21, 2005

RHESSI -ray imaging

PTA, September 21, 2005 2

-1.79x1020 Mx

-1.02x1020 Mx

+1.91x1020 Mx

+0.19x1020 Mx

+0.63x1020 Mx

-0.27x1020 Mx

I

II

III

IV

V

VI

Courtesy Y.H. Yang; cf H.M. Wang et al., ApJ 576, 497 (2002)

PTA, September 21, 2005

Flare/CME energetics

PTA, September 21, 2005

Kopp et al., 2004

PTA, September 21, 2005

Dennis et al., 2005

PTA, September 21, 2005

If these SEPs are accelerated by CME-driven shocks, they use a significant fraction of the shock kinetic energy (~3% to 20%)

(Mewaldt et al., 2005; see also Emslie et   al. 2005).

PTA, September 21, 2005

Flare development: magnetic restructuring

and energy transport

PTA, September 21, 2005

Evidence for a large-scale coronalcurrent sheet? Sui & Holman, 2004

Anzer & Pneuman, 1982

PTA, September 21, 2005

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MDI magnetic artifacts

PTA, September 21, 2005

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“Opacity minimum” flare IR observations(Xu et al., 2004)

PTA, September 21, 2005

Deposited Energy vs Footpoint Separation

Mar 18, 2003

From Magnetogram:

Bfp 500 G

Assume:

Bcorona Bfp/5

Ar = Lh·Lv 360 arcsec2

Perpendicular motion

From HXR image:

Lh 5-10 arcsec

Lv 36-72 arcsec (lower limit !!)

PTA, September 21, 2005

Shrinking magnetic field? Veronig et al., 2005; now have ~5 RHESSI events

PTA, September 21, 2005

TRACE observations of white light and UV emissions, flare of 2004 July 22

n.b. TRACE “white-light” response includes the UV, hence most of the flare luminosity

“White light” Difference(reversed)

UV 1700A

PTA, September 21, 2005

Coronal magnetic field

• Quantitative before/after magnetic models

• Aly conjecture

• Use of images (“data assimilation”)

• Problems - focusing the energy, accelerating particles, launching shock

• What is the eigenmode structure of an active region?

PTA, September 21, 2005

“Isomagnetobars”Before

After

PTA, September 21, 2005

End

http://sprg.ssl.berkeley.edu/~tohban/nuggetshttp://solarmuri.ssl.berkeley.edu/~hudson/cartoons

PTA, September 21, 2005

Microflares and jets

PTA, September 21, 2005

One month of RHESSI microflare observations

Map of ~2000 flare locationsof tiny flares seen by RHESSI (microflares)

RHESSI microflares take place in active regions

Rauscher et al. 2004

PTA, September 21, 2005

Imaging the bremsstrahlung from type III burst electrons?

PTA, September 21, 2005

X17 flare of 2005 Sept. 7 17:17 UT

(courtesy S. Krucker)

cf. Qiu et al. 2004