pta, september 21, 2005 solar flares in the new millennium h.s. hudson space sciences lab, uc...

PTA, September 21, 2005

Solar flares in the new millennium

H.S. Hudson

Space Sciences Lab, UC Berkeley


Solar flares since 1991

H.S. Hudson

Space Sciences Lab, UC Berkeley


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

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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!


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)


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

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

CH

Distribution of coronal plasma


Yohkoh, RHESSI, TRACEand ground-based data:

Recent wonders and marvels


Movie of dimming (Aug 28, 1992)

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Coronal Dimming

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TRACE 1600A

TRACE 171A

Shrinkage, dimming, destruction, oscillation

Helix, ribbons (separatrices?)


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)


Flare/CME energetics


Kopp et al., 2004


Dennis et al., 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).


Flare development: magnetic restructuring

and energy transport


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

Anzer & Pneuman, 1982


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MDI magnetic artifacts


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


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 !!)


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


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


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?


“Isomagnetobars”Before

After


End

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

http://sprg.ssl.berkeley.edu/~tohban/nuggets

http://solarmuri.ssl.berkeley.edu/~hudson/cartoons


Microflares and jets


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


Imaging the bremsstrahlung from type III burst electrons?


X17 flare of 2005 Sept. 7 17:17 UT

(courtesy S. Krucker)

cf. Qiu et al. 2004

pta, september 21, 2005 solar flares in the new millennium h.s. hudson space sciences lab, uc...

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