# Presentation: 669216

## Combined WIND-RHESSI-TRACE studies

- Sam Krucker
- Space Sciences Lab, UC Berkeley

- .

- .

- The origin of solar impulsive energetic electrons: combined observations

## Impulsive electron events

**observed at 1 AU**

- WIND/3DP:
- ~15 event/year during solar min.
- STEREO/STE:
- 50 times more sensitive
- below 30 keV  more events

- STEREO
- first
- 2 years

## STEREO/STE observations

- Solid state detectors down to 2 keV (wind/3dp: 30 keV)
- 50 times more sensitive                               5 times more events
- Accurate onset times down to 2 keV
- 2 point measurements + WIND

## ?

- <date/time>

**?**

**Sun**

**EM **
**radiation**

**REMOTE sensing**
** ****observations**

**energetic electrons escaping**
**from the Sun**

**IN-SITU electron observations **
**STEREO, WIND, ACE**

**e****-**

- magnetic
- field line

## FLARE accelerated electrons escape

**Sun**

**FLARE accelerated electrons escape**

**IN-SITU electron observations **
**STEREO, WIND, ACE**

**e****-**

- magnetic
- field line

**flare**

## FLARE accelerated electrons escape

**Sun**

**IN-SITU electron observations **
**STEREO, WIND, ACE**

**e****-**

- magnetic
- field line

**flare**

**e****-**

**FLARE accelerated electrons escape**

## main flare

**IN-SITU electron observations **
**STEREO, WIND, ACE**

**Sun**

**EM radiation**

**REMOTE sensing**
** ****observations**

**Escaping electrons could also be accelerated late in the flare**
****** ****no correlation with impulsive phase**

**e****-**

- magnetic
- field line

- HXR footpoints

**acc. site of escaping electrons**

**flare**

## SHOCK accelerated electrons

**IN-SITU electron observations **
**STEREO, WIND, ACE**

**SHOCK accelerated electrons**

**e****-**

- magnetic
- field line

- Flare accelerated electrons do not escape or escape along field lines not connected to the spacecraft

**shock**

**flare**

## Flare or shock acceleration?

- Different **timing**
- Depending of **magnetic connection** different component are observed

## Timing

- From onset times at 1 AU (velocity dispersion) solar release time can be approximated.
- Controversy: propagation effect or scattering?

- Slope gives path length
- Intersection gives release time

- 30 keV

## Timing

- From onset times at 1 AU (velocity dispersion) solar release time can be approximated.
- Controversy: propagation effect or scattering?

- WIND/3DP
- Electrostatic analyzers: large error bars
- Solid state detectors: SMALL error bars
- (~few minutes)

- 30 keV

## Timing

- From onset times at 1 AU (velocity dispersion) solar release time can be approximated.
- Controversy: propagation effect or scattering?

- WIND/3DP observerations Electrostatic analyzers: large error bars
- Solid state detectors: SMALL error bars
- (~few minutes)

- STEREO/STE
- Solid state detectors down to 2 keV

- STEREO

## What is reported?

**What is reported?**

- magnetic
- field line

**e****-**

** ****Same timing as flare for some events**

**shock**

**flare**

**What can be done with multi-point measurements? **

- e.g. Krucker et al. 1999, Maia & Pick 2004, Klein et al. 2005

## What is reported?

**What is reported?**

**e****-**

- magnetic
- field line

** ****Same timing as flare for some events**
** ****>30 keV electron often delayed ******** shock**

**shock**

**flare**

**What can be done with multi-point measurements? **

- e.g. Krucker et al. 1999, Haggerty & Roelof 2002, Maia & Pick 2004, Klein et al. 2005

## What is reported?

**What is reported?**

**e****-**

- magnetic
- field line

**e****-**

** ****Same timing as flare for some events**
** ****>30 keV electron often delayed ******** shock**
** ****<20 keV more often with flare**

**shock**

**flare**

**What can be done with multi-point measurements? **

- Wang et al. 2006

## What is reported?

**What is reported?**

**e****-**

- magnetic
- field line

**e****-**

** ****Same timing as flare for some events**
** ****>30 keV electron often delayed ******** shock**
** ****<20 keV more often with flare**
** ****timing different because of scattering         ******** all events are flare related**

**shock**

**flare**

**What can be done with multi-point measurements? **

- Cane 2004

## earlier                               

- magnetic
- field line

**e****-**

**Early on, only one spacecraft is connected to the shock**

- earlier

**shock**

## earlier                         later      

**e****-**

- magnetic
- field line

******  ****different onset times are expected**

**e****-**

**Early on, only one spacecraft is connected to the shock**

**e****-**

**Later both spacecrafts are connected to shock**

- earlier                         later

**shock**

**shock**

## flare

**Later onset **

**Shock accelerated electrons are seen by STEREO 2**

**e****-**

- magnetic
- field line

**STEREO 1:**
**Earlier on set expected**

**e****-**

**Flare accelerated electrons are seen by STEREO 1**

**shock**

**flare**

## Timing alone not conclusive.Combination with imaging and modeling needed!

## e-

**Electrons lose their **
**energy by collisions**
** ****X-ray emission**
** ****heating**

**Escaping electrons produce type III bursts**

- heating

**e****-**

**e****-**

## Coronal imaging

**Sun**

**e****-**

- EUV/X-ray observations reveal coronal structures.
- STEREO: 3d structure, SOLAR B: X-rays, B, flows, RHESSI: HXRs

- jet

## movie 

## Coronal imaging

**Sun**

**e****-**

- EUV/X-ray observations reveal coronal structures.
- STEREO: 3d structure, SOLAR B: X-rays, B, flows, RHESSI: HXRs

- jet

- What are chances to observed an event?
- How to coordinate observations?

## Radio tracking

- type III bursts (electron beams)

- <16 MHz: STEREO/WAVES

- 400-150 MHz: NRH
- In  the future: FASR

**Simulated**
- radio positions

- 1-2 solar radii

- open field line

## potential magnetic field extrapolation (Schrijver & Derosa 2003) 

- Only open field lines are plotted.

**N**

**S**

**N**

- to Earth

**432 MHz**
**327 MHz**
**164 MHz**

- Radio tracking (K.-L. Klein):

**type III**

**type III**

- May 1, 2000

## flare

**Type II burst:**
**RADIO TRACKING gives **
**shock location**

**e****-**

- magnetic
- field line

**e****-**

**Type III burst:**
**RADIO TRACKING gives path of electron beam**

**shock**

**flare**

- Compare with onset times & 3D observations & modeling

## What is possible?

**Type II burst:**
**RADIO TRACKING gives **
**shock location**

**e****-**

- magnetic
- field line

**e****-**

**Type III burst:**
**RADIO TRACKING gives path of electron beam**

**shock**

**flare**

- Compare with onset times & 3D observations & modeling

## Summary

- Combined observations have great potential
- Timing studies combined with imaging and modeling

## Comparing spectra

- PHOTON SPECTRA:
- Produced by downward moving electron beam

- ELECTRON SPECTRA:
- spectrum of escaping electrons
-  rough correlation

****

****

## Comparing spectra

- PHOTON SPECTRA:
- Power law fit to HXR
- spectra averaged over peak

- ELECTRON SPECTRA:
- Power law fit to peak flux

- Assuming power spectra:
- THIN:        =  – 1
- THICK:     =  + 1
- RESULTS:
- correlation seen
- values are between

****

****

## flare

**No particles seen**

**STEREO 2 is not connected to flare site**

- magnetic
- field line

**STEREO 1**

**e****-**

**Flare accelerated electrons are seen by STEREO 1**

**flare**

-  Better estimates of total number of electrons (energy)

## Electron spectrum at 1AU

- Typical electron spectrum can
- be fitted with broken power law:
- Break around: 30-100 keV
- Steeper at higher energies

- Oakley, Krucker, & Lin 2006