Constraints on Particle Acceleration from Interplanetary

Observations

R. P. Lin together with L. Wang, S. Krucker at

UC Berkeley, G Mason at U. Maryland, and R. Mewaldt at Caltech

Krucker and Lin 2002

Electron -3He-rich SEP events

- ~1000s/year at solar maximum

- dominated by: - electrons of ~0.1 (!) to ~100 keV energy

- 3He ~10s keV/nuc to ~MeV/nucx10-x104 (!) enhancements

- heavy nuclei: Fe, Mg, Si, S enhancements- high charge states

- associated with:

- small flares/coronal microflares - Type III radio bursts - Impulsive soft X-ray bursts (so also called

Impulsive SEP events)

L=v(t-to) or L/v=t-to ~0.05 MeV/nuc -1/v of 3He (Mason & Mazur)

~1.5 MeV/nuc - 1/v for Electrons /

Electrons 0.14–13 keV

Electrons 20 – 350 keV Ions ~ 0.5 – 1 MeV

Electron spectrum at 1AUTypical electron spectrum can be fitted with broken power law:

Break around: 30-100 keVSteeper at higher energies

Oakley, Krucker, & Lin 2004

Comparing spectraPHOTON SPECTRA:Power law fit to HXR spectra averaged over peak

ELECTRON SPECTRA:Power law fit to peak flux

Assuming power spectra:

THIN: = – 1THICK: = + 1

RESULTS:1) correlation seen2) values are between

Wang, Krucker, Lin, & Gosling, 2005

Wang, Krucker, Lin, & Gosling 2005

Wang, Krucker, Lin, & Gosling 2005

Wang, Krucker, Lin, & Gosling 2005

The Sun is the most energetic particle accelerator in the solar system:

- Ions up to ~ 10s of GeV - Electrons up to ~100s of MeV

Acceleration to these energies occurs in transient energy releases, in two (!) processes:

- Large Solar Flares, in the lower corona

- Fast Coronal Mass Ejections (CMEs), in the inner heliosphere, ~2-40 solar radii

X-Class Flare of 2002 July 23

• 00:27:20–00:43:20 UT• GOES X4.8• Location: S13E72

(Lin et al. 2003)

RHESSI Gamma-Ray Flares2002 July 23 X4.8

2003 June 17 M6.9

2003 October 28 X17

2003 October 29 X10

2003 November 2

X8.3

2003 November 3

X3.9

2004 November 10

X2.5

2005 January 15 X2.6

2005 January 17 X3.8

2005 January 19 X1.3

2005 January 20 X7.1

Ramaty High Energy Solar Spectroscopic Imager (RHESSI)

Mewaldt et al 2005

(Mewaldt et al. 2005)

Oct. 28, 2003, RHESSI solar count spectrum from 11:06:20 – 11:10:04 (Smith et al. 2004, Share et al. 2004)

e+ - e- n-capture

bremsstrahlung

narrow linesbroad lines

Murphy 2004

Energetic Proton Power-law Exponents

28 Oct 03 2 Nov 03

S16E08 S15W56

γ-ray lines Energy range γ-ray (SEP) γ-ray (SEP)

Ne/C+O 2-20 MeV 2.0-3.2 (1.3) 1.6-3.2 (1.7)

e+/C+O 10-50 MeV 2.2-3.3 (2.0) 2.3-3.3 (2.8)

n-capt/C+O 10-100 MeV 2.8-3.8 (2.5) 2.8-3.8 (3.0)

GOES soft X-rays

RHESSI 2.2 MeV line

RHESSI 100-200 keV

RHESSI hard X-rays

WIND/WAVES radio

WIND/3DP electrons

20 Jan 05 FlareRHESSI Gamma-ray Spectrum - 20 Jan 05 Flare

In the Jan 20 Event the high energy particle-intensities reach Earth just minutes after the x-rays from the flare

RHESSI X-ray imaging during HXR peak:

X-ray imaging

Two ribbon flare with HXR footpoints (contours) with thermal loop (image)

TimingRed line (06:48UT):Solar release time derived from onsets at 1 AU assuming first arriving particles travel with the speed of light along L=1.2 AU

LASCO (06:54UT): Around ~3 solar radii; lines show height assuming a constant velocity.For v=2500km/s, CME could be at ~1.5 solar radius at particle release time.

Red crosses:Rising SXR loops (top of SXI emission)

2.2 MeV peaks at 06:47:30UTHXRs peak at 06:45:00UT