# Presentation: 565228

## Timing Issues for 2005 Jan 20Stephen White, summarizing everyone else’s work

- Address the relative contributions of “flare” and “CME” accelerated particles to SEPs
- Investigate shock acceleration
- Why this flare? Because
- the protons arrive at Earth so quickly that they supply stronger constraints on acceleration timing than in most events
- and as a GLE it must have accelerated protons to several GeV very quickly
- etc, etc

## CME launch

- Controversy over CME speed and launch: LASCO sees CME in only 1 frame (06:54, CME height 3.5 Rsun, 2000 km/s for onset at 06:33).
- EIT has frames at 06:24, 06:36, 06:48. A distinct loop is present at 06:24 and has moved to height 0.3 Rsun by 06:36.
- CME speed of order 3000 km/s and extrapolated onset time of 06:33 depend on analysis of these frames and assumption that this loop is the CME – doesn’t look to be enough mass there in these frames.
- But: the other GLEs have fast CMEs, expect this one to.

## First evidence for particle acceleration: HXR

- Full time range

- Early onset

## First evidence for particle acceleration: waves

- A

- Full time range

- Early onset

## Shock formation? No radio before 06:41

- A

## Shock formation?

- Type II reports
- Culgoora
- 06:44
- 180 MHz
- Learmth
- 06:44 to 07:00
- 180 MHz
- San Vito
- 06:44
- 180 MHz

## Shock formation? WAVES spectrum

- Type II: not clear before 07:12 UT.
- Emission at 8 MHz at 07:12 UT: if II, then height > 5 Rsun.
- Propagation at 3000 km/s since 06:33: 10 Rsun.

## Open versus closed field lines

- Hard X-rays and microwaves require acceleration of nonthermal electrons up to about 1 MeV by 06:36:00
- Fluxes large (double total solar flux) but low turnover frequency at this stage: source could be higher in corona
- But there is no low-frequency emission before 06:40: en-ergy release on closed fields, no access to open field lines?
- We know that the HXR and microwaves come from very low in the corona, closed field lines: cannot supply from a shock.
- Disturbance drifting outwards after 06:40 in dynamic spectrum: shock? No clear Type II: not secure to use 06:44 for timing of shock formation.

## Main energy release

- HXR, microwave and soft X-rays all show the onset of the main energy release to be at about 06:43, peak at 06:46
- CORONAS/SONG data: MeV photons also peak at about 06:46, above background at 2-6 MeV at 06:43:30.
- Pions probably present by 06:45, peak at 06:46.
- GeV Protons start to arrive at South Pole NM at 06:48:30, 5 minutes after first sign of MeV protons at the Sun. Excess propagation time over EM radiation should be about 3 minutes (2 minutes leeway).
- Wide range of SEP energies arrive simultaneously

## Timing Summary (Earth time = Sun event time + 8 minutes)

- 06:33:   possible CME lift-off based on EIT extrapolation
- 06:35:   onset of nonthermal acceleration in low corona on
-              closed field lines (HXR and microwave precursor)
- 06:36:   EIT loop at height 0.3 Rsun; likely CME lift-off time
- 06:41:   First radio emission at low frequencies, open field
-              lines. No clear evidence for shock.
- 06:43:   Onset of main energy release; alternative CME liftoff?
- 06:44:   nominal onset of Type II – not confirmed. CME likely
-              at height ~1.5 Rsun – too high to explain flare emission
- 06:45:   Pions present at Sun (CORONAS and RHESSI)
- 06:45:   nominal departure of GL protons from Sun (+/- 1 min;
-              this is just the Earth arrival time minus 3 minutes)
- 06:46:   Peak of main energy release
- 06:48:30: first ground-level protons arrive at South Pole
- 06:53:   Peak of GLE pulse 1 (impulsive peak) at Earth
- 06:54:   CME at height 3.5 Rsun – has to be at least 2000 km/s