# Presentation: 040741

## First Resultsfrom the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI)

- Brian Dennis
- GSFC
- 11/04/2002

## Slide 2

**Notes:**
13.

## Launch and Ascent to Orbit

- Drop Time: 05-Feb-2002  20:58:10.665 UTC

## Slide 5

## RHESSI Spectral Coverage

## Slide 7

**Notes:**
15. feb20_1106_lightcurves

## Slide 8

**Notes:**
16. feb20_1106_cleaned_maps

## Slide 9

**Notes:**
Page 17.

## Slide 10

## Slide 11

## SOHO – TRACE – RHESSI MovieTom Bridgman, Scientific Visualization Studio, GSFC

## TRACE 195-Å Response

- TRACE 195-Å Response

- Fe XXIV

- Fe XII

- Temperature (K)

- TRACE response (DN cm5 s-1 pix-1)

## RHESSI / TRACE Overlay

- Image at start of a large solar flare
- Red contours from RHESSI show  12 – 25 keV X-ray flux.
- Green and white image from TRACE (195 Å) shows EUV emission from cooler plasma(~2 MK).
- Solar limb runs from top to bottom of image.

## RHESSI / TRACE Overlay

- Later during the same flare.
- Red contours from RHESSI show 12 – 25 keV X-ray flux.
- Blue contours from RHESSI show 50 – 100 keV X-ray flux.
- Green and white image from TRACE (195 Å) shows EUV emission from Fe XII at ~1.5 MK and from Fe XXIV at 15 – 20 MK..
- Solar limb runs from top to bottom of image.

## TRACE - RHESSI Movie

## RHESSI – TRACE MovieGreen – white: TRACE 195 Å, Blue: RHESSI 50 – 100 keV, Red: 12 – 25 keV

## RHESSI (12 – 25 keV)    TRACE (195 Å) Overlay

- RHESSI (12 – 25 keV)    TRACE (195 Å) Overlay

## RHESSI (12 – 25 keV)    TRACE (195 Å) Overlay

- RHESSI (12 – 25 keV)    TRACE (195 Å) Overlay

## Red:12 – 25 keV, blue: 50 – 100 keV - TRACE (195 Å)

- Red:12 – 25 keV, blue: 50 – 100 keV - TRACE (195 Å)

## Red:12 – 25 keV, blue: 50 – 100 keV - TRACE (195 Å)

- Red:12 – 25 keV, blue: 50 – 100 keV - TRACE (195 Å)

## Major Hard X-ray Peak04/21/2002 01:15:17.3 – 01:15:42.1 UTCleaned Maps

- Major Hard X-ray Peak04/21/2002 01:15:17.3 – 01:15:42.1 UTCleaned Maps

## RHESSI Imaging Spectroscopy 

- X1.5 Flare
- 21 April 2002
- 01:15 UT

## RHESSI Imaging Spectroscopy

- E-3.2

- E-7

## Flare Energy Budget

- “The >20 keV electrons contain 10 to 50% of the total energy output” Lin and Hudson (1976).
- Not a single component of the energy budget “is presently known to better than an order of magnitude” (Hudson 1986).
- Energy in electrons is uncertain because of lower energy cutoff to spectrum.
- Thermal energy in plasma is uncertain because of uncertain volume, density, filling factor.
- Only plasma in narrow temperature range is generally imaged.

## Slide 26

## SXR:HXR Ratio vs. Flare SizeVeronig et al. A&A, 392, 699 (2002)

## The Neupert Effect

- The time integral of the hard X-ray emission closely matches the temporal variation of the soft X-ray emission.
- Implies that accelerated electrons that produce the hard X-rays also heat the plasma that produces the soft X-rays.

## The Neupert Effect

## RHESSI – GOES Comparison

- RHESSI25 – 50 keV

- GOES 1 – 8 Åtime derivative

## Slide 31

## A

- B

- C

## C

- A

- B

## RHESSI Spectra

## A

- B

- C

## C

- A

- B

## TRACE light curves19.5 nm

- RHESSI light curve25 – 50 keV

- Region
- A

- B
- C

## Slide 38

## The Flare Decay Phase

- Flare was observed with RHESSI for over 12 hours after the GOES peak at energies below 10 keV
- Coronal source moved to higher altitudes reaching ~140,000 km above the limb.
- Higher energy source (6 – 12 keV) was always higher than lower energy source(3 – 6 keV).

## GOES Lightcurve

## Slide 41

## SolarLimb

- SolarLimb

## Slide 43

## Švestka’s Scenario (1987)Svestka et al., Solar Physics, 108, 237, 1987 

## CME Height & Velocity vs. Time

## CME Height vs. TimeGallagher et al., in preparation

- CME Height vs. TimeGallagher et al., in preparation

## CME Height vs. TimeGallagher et al., in preparation

## Flare - CME InitiationWang et al. 2002, Ap. J. 572: 580.

## Conclusions

- RHESSI is operating almost flawlessly.
- Over 3000 events listed in the RHESSI “flare” catalog.
- Gamma-ray line flare detected on July 23.
- Crab pulsar detected in June at time of closest approach. Image of nebula possible.
- Several gamma-ray bursts detected with high energy resolution.
- Hope for several years of observations – no consumables.
- All data and analysis software freely available on line.
- Please come help us to make full use of the observations!

## Summary

- Energy in accelerated electrons > energy in SXR-emitting thermal plasma
- Energy in electrons is a smaller fraction of thermal energy in smaller flares.
- General agreement with Neupert Effect.
- Poor spatial correlation between hard X-ray and EUV brightenings.
- Long–duration energy release after SXR peak with no electron acceleration.

## Flare Model Cartoons

- Grand Archive of Flare and CME Cartoons  _[http://](http://solarmuri.ssl.berkeley.edu/~hhudson/cartoons/)__[solarmuri.ssl.berkeley.edu/~hhudson/cartoons](http://solarmuri.ssl.berkeley.edu/~hhudson/cartoons/)__[/](http://solarmuri.ssl.berkeley.edu/~hhudson/cartoons/)_
- Kopp and Pneuman ModelKopp and Pneuman, Solar Phys. 50, 85 (1976).

## Cliver’s Flare ModelCliver, et al., ApJ 305, 920 (1986). 

## Shibata’s Flare ModelK. Shibata, Astrophys. and Space Science 264, 129, 1998 

## Three-dimensional magnetic reconnection Gosling, J. T., Birn, J., and Hesse, M., GRL 22, 869 (1995). 

## Summary

- X-rays seen before TRACE brightening at same location
- 3-25 keV X-rays start at 00:40 UT
- TRACE 195Å brightening at 00:45 UT
- >25 keV X-rays from site of TRACE ribbons
-  E-3.2 spectrum (S. Krucker)
- Gradual variations, >1 min. time constant.
- Neupert Effect
- >25 keV time profile “matches” soft X-ray time derivative
- Coronal X-ray source
- Initially E-7 spectrum (S. Krucker)
- Moves up for >12 hours after peak time
- Initial velocity = 10 km s-1, changing to 1.7 km s-1 at ~03:00 UT
- TRACE feature moves up at ~100 km s-1 (P. Gallagher)
- LASCO CME velocity = 2500 km s-1 (G. Lawrence)
- CME at Earth with velocity of 800 km s-1 (E. Roeloff)
- >300 keV electrons seen with ACE injected at 01:33 UT (E. Roeloff)