First RHESSI ResultsBrian R. Dennis

RHESSI Mission ScientistCode 682

Space Sciences DirectorateMonthly Report

Monday, 25 March 2002

25 March 2002 RHESSI Results 2

The Reuven RamatyHigh Energy

SolarSpectroscopic Image

-RHESSI

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Solar Flares

• Biggest explosions in the solar system- 1032 ergs or a billion megatons of TNT

• Heat plasma to tens of millions of degrees.• Accelerate particles to near the speed of light

- electrons to >100 MeV- ions to >10 GeV.

• Magnetic energy released in the solar corona – mechanism unknown.

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Biggest Explosions(in tons of TNT equivalent)

• Conventional TNT 3.8x103

• Atomic bomb (Hiroshima) 1.3x104

• Hydrogen bomb 2x107

• Tunguska event (1908) 1x107

• Mount Pinatubo (1991) 7x107

• Largest earthquake (Chile 1960) 3x109

• Asteroid that wiped out dinosaurs 1014

• Comet Shoemaker-Levy 9 on Jupiter 1014

• Largest solar flare 1016

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Solar Flares How do you determine the energy release mechanism(s)?

• Observe emissions from the heated plasma

- Traditional H-alpha, UV, EUV (SOHO, TRACE), soft X-rays (Yohkoh)

- Reveals magnetic field morphology

- All energy release processes produce heat.

• Observe the accelerated particles in space

- ACE, WIND, SOHO, etc.

- Many particles do not escape from the Sun

- Transportation effects modify the information

• Observe the emissions from the accelerated particles

- Hard X-rays from electrons, gamma-rays from ions

- Provides the most direct signature of the energy release mechanism(s)

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First RHESSI Flare Movie

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What’s Going On?

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RHESSI/SOHO/TRACE Overlay

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RHESSI Flare Spectra

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RHESSI Footpoint Flare

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RHESSI – SOHO (EIT) Overlay

20 Feb. 2002 11:06 UT

Color: EIT

Contours: RHESSI 30 – 80 keV15 – 90% levels

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Shutters-Out Sensitivity

GOES C-level

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Gamma-Ray Burst

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RHESSI Minimum Science Requirements

4.1.2.1 Perform hard X-ray (greater than 20 keV) imaging spectroscopy of solar flares with better than 4 arcsec spatial resolution and better than 3 keV energy resolution.

4.1.2.2 Perform high resolution (better than 3 keV FWHM at l MeV) spectroscopy of gamma-ray lines in solar flares.

 4.1.2.3 Obtain observations of at least a hundred hard X-ray flares

and ten gamma-ray (greater than 300 keV) flares.

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Solar Cycle Predictions

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Summary

• RHESSI almost fully operational

• All data and analysis software released

• About 30 hard X-ray flares observed

• Waiting on the Sun for Gamma-ray flares

• Looking forward to many years of observations