SUMER Study: Flare Watch 21 Apr 2002

Animations

If you click on the first image

you will see an animation of EIT images during the four hours that include the SUMER study described below. The position of the 4"x300" SUMER slit is marked. The animation covers the X flare and the following CME.

If you click on the second image you will see an animation of SUMER spectra during the first (one hour) phase of the X flare, combined with the first EIT images that were taken in parallel. The spectral window contains approx. 2 Å around the Fe XXI (1354 Å) line, which means that velocities up to +/- 240 km/s can be observed in plasma of ~10 000 000 K.

Technical Details of the Study

date, time: 21.Apr.02, 00:36 - 03:53 UT
field of view: 990 arcsec W, 350 - 50 arcsec S
slit: 4.0 arcsec x 300 arcsec (number 1)
raster step size: 0.0 arcsec (0 elementary steps)
exposure time: 49.5 seconds
telemetry: 3(windows)*235 images of 50 spectral x 360 spatial pixels (format 8)
compression: quasilog-min-max (method 5)
wavelengths:
1354.00 Å on reference pixel 473 of Detector A
1349.36 Å on reference pixel 580 of Detector A
1335.13 Å on reference pixel 910 of Detector A
rotation compensation: no
binning: no spectral, no spatial
on-board flat field correction: no

Notes: In a first approach, three full detector images (format 2) were neglected and only images in format 8 were put together. Deadtime correction was neglected because of a count overflow.

Observations and Related Publications

These are some SUMER Fe XXI spectra from the first hour, the onset phase of the flare, inserted in the most recent EIT Fe XII images, also showing the position of the SUMER slit. The spectral window contains Doppler shifts of 240 km/s to the red and the blue; in the left part of the window there is an unidentified weak coronal line.

SUMER observes the first sign of the flare at 00:48 UT when a shock front arrives with high Doppler flows (> 300 km/s) in Fe XXI. At 00:54, the flare site brightens and oscillation events can be observed. Around 01:15, SUMER is overexposed in Fe XXI. After 02:15, a CME is seen in Fe XII, C II, and Continuum. A spatial/temporal correlation of Fe XXI and Continuum ("Bremsstrahlung") is observed in the flare phase, as well as a correlation of Fe XXI and C II, incl. their Doppler shifts.

Parts of these observations were already recorded for earlier flares and have been (or will be) published, e.g.

Innes DE, Curdt W, Schwenn R, Solanki SK, Stenborg G, McKenzie DE: Large Doppler shifts in X-ray plasma: An explosive start to coronal mass ejection, ApJ 549, L249 (2001)
Torsti J, Kocharov L, Innes DE, Laivola J, Sahla T: Injection of energetic protons during solar eruption on 1999 May 9: Effect of flare and coronal mass ejection, A&A 365, 198 (2001)
Kliem B, Dammasch IE, Curdt W, Wilhelm K: Correlated dynamics of hot and cool plasma in the main phase of a solar flare, ApJ 568, L61 (2002)
Wang TJ, Solanki SK, Curdt W, Innes DE, Dammasch IE: Doppler shift oscillations of hot solar coronal plasma seen by SUMER: A signature of loop oscillations? (subm. to ApJ Letter)

Spectral Windows (averaged)

C II

Fe XII, Continuum

Fe XXI

In the 2D images below, observation time runs from left to right. Images show continuum and line radiances on a logarithmic scale, line shifts scaled between -50 and +50 km/s, and line widths scaled between 10 and 150 km/s.

Cont 1349 (10 000 K)

C II 1335 (23 000 K)

Fe XII 1349 (1 400 000 K)

Fe XXI 1354 (~ 10 000 000 K)

Fe XXI Events in SUMER Study Starting 21.Apr.02, 00:36 UT

Time  Solar X Solar Y    Intensity    Size   Shift   Width
/UT   /arcsec /arcsec   /count s-1 /arcsec /km s-1 /km s-1
----- ------- ------- ------------ ------- ------- -------
00:54     989    -230      15.6690      20      58     145
01:03     989    -213      39.3676      20      63     132
00:57     989    -280      27.7430      20     110     122
00:58     989    -298      26.1288      20      95     132
01:23     989    -345      7.80056      40     101     147
01:49     989    -187      589.215      70      72     150

IED, 02 May 2002

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