Stereoscopic Solar Flare 5th May 2007, 1220 hours GMT
Sunspot 10953

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Sunspot NOA 10953  was detected, before it emerged onto the solar disc, by the GONG helioseismology network. It developed on the far side of the sun. It was an active spot with several flares before this one.

H-alpha image taken in China. This is one day before the flare.

I thought the filament seen in the sunspot was the erupted material during the flare, but checking the Spanish movie below, the filament remained intact and the tsunami seemed to come from the left and larger ribbon of the flare (E), which needs an explanation, but I cannot provide one. Another filament below the flare (S) showed up in H alpha after the tsunami hit it. This dark "filament" may have actually been the "splash" high into the corona as the tsunami plowed into the coronal plasma. Examine the sequences provided on the next 5 pages and form your own opinion!

H-alpha image sequence during the flare from Gema Araujo (Spain) using a PST. Also available as a movie on his web site and as a GIF movie here.

During the solar 5th May flare: 171 Angstrom stereoscopic images

Use red/cyan anaglyph glasses to see the STEREO images in 3D.

Late in the flare: post-flare loop and filament eruption.

Image Credit:
NASA/JPL-Caltech/NRL/GSFC. - Anaglyph and roll-over by John Wattie

Roll-over stereoscopic image: red/cyan anaglyph

• Run your mouse over then off the image below, while wearing red/cyan goggles.

1. During the solar flare
2. Late in the flare, showing filament eruption and post-flare loop.

Stereo parallax 1/32 disc center to edge

1. The sun rotates between the two images.
2. The shock wave started by the flare, distorts southern structures and they wave back and forth (better seen on the gif movie coming). The shock wave followed a narrow path, which was directed by the magnetic field, already present before the flare began, as page 2 will show. It also avoided entering the coronal hole.
3. The dark ejection closely following the shock wave looks like a"solar tsunami." The tsunami has a component which stays fairly low in the corona and curves around parallel to the solar surface, but part of the front breaks up as a thin, ragged, dark band, with components spurting up into the higher corona. Without 3D, this behaviour is hard to see.
4. Comparison with the GOES x-ray data shows the tsunami heading south before the soft x-ray emission from the solar flare begins to rise. (The x-ray emission has a step in its rise, but I cannot see any evidence on these images to explain the two phases).

LASCO coronagraph images from SOHO did not show any CME (Coronal Mass Ejection)
H1 imager data from STEREO did not show a CME
and so the elevated shock front did not leave the sun:

The 3D pictures here seem to show the tsunami starting deep down - probably near the photosphere, but it would be a big help to have simultaneous stereoscopic H alpha images to prove that. What a great shame STEREO does not have H alpha cameras!

The description I originally gave seems to disagree with the 2D H alpha sequence showing the southern extension of the tsunmi recently provided, at my request, by Gema Araujo (Page 5) (20 Dec 2007 - thank-you Gema).

However, I give the original description again here because it makes more physical sense (to me) and the 195 Å Flash movie I derived months ago by digital subtraction from the STEREO image sequence seems to clearly agree with my first description. This shows how it can be confusing to only examine one wavelength during solar activity:

The tsunami seems to be ejected from between the two ribbons that form early in the solar flare. Solar flare ribbons form in the foot-print of the magnetic cavity which contains the filament. The filament lies in the magnetic neutral zone of the sunspot complex. The ribbons in this case look as if they guide the tsunami direction, like the runway lights at an air-port guide an aircraft's take-off.  The filament heats up (brightnens in 195Å), expands and is shot out of its cavity, like a shell from a cannon, to make the tsunami.

Page 1 Solar Flare and Tsunami, event gev_20070505_1220 (3D)
Page 2 Subtraction Images (2D)
Page 3 GIF movie, 171 Å (2D)
Page 4 Flash movie, 195 Å (2D)
Page 5 H alpha GIF movie (2D)

Page 6 Comparison of H-alpha and 195Å movies.

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