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Images of the Sun taken by the
Transition Region and Coronal Explorer

The TRACE images may be used without restrictions in publications of any kind. We appreciate an acknowledgement indicating that the Transition Region and Coronal Explorer, TRACE, is a mission of the Stanford-Lockheed Institute for Space Research, and part of the NASA Small Explorer program. More information on TRACE and other TRACE images can be found here.
Coordinated flares in AR9433
Active Region 9433 has been generating a number of C and M flares as the region grew in complexity. There have been two areas of strong shears, one in the leading and one in the trailing area. Most of the flares have been confined primarily to one or the another area. However, the M3 flare at about 13 UT on 24 April 2001 shows a peak in both simultaneously, suggesting that these two zones have now become coupled magnetically. The X-like pattern of dots centered on each of the bright Fe IX/X 171Å flares is a diffraction pattern from the very bright kernels in the flares. Also note the thin ring of emission surrounding the left (eastern) flare. Courtesy: Dick Shine.
Flare in AR 9433
This is an image taken on April 19 2001 at about 13:30 UT of Active Region 9433 (which is the second passage across the solar disk of what was AR 9393 during the first passage; then it produced a bunch of X-class flares). This image (rotated over 290 degrees) is in the 171Å bandpass (1 million Kelvin) and shows some post flare loops, cooling after an M2 flare that started two hours prior to this image. Courtesy Dawn Myers.
X14.4 in 171Å X14.4 in 1600Å

Easter Sunday: X14.4 flare

On 15 April 2001 (Easter Sunday), Active Region 9415 caused an unusually large flare, listed as X14.4 - likely to be remembered as the 5th largest on record (see this GOES X-ray flux plot, showing the Sun's entire X-ray flux going up by a factor of 1,000). The flare started around 13:19UT, and produced intense X-rays, and later, as the flare plasma cooled down, very bright Extreme Ultraviolet emission observed by TRACE. This (QuickTime; MotionJPEG/A compressed, Interlaced Odd; 25MB) 171Å movie shows some of the pre-flare activity, and also the contraction and later expansion of the high coronal loops well above the flare (note that the quality of these images seems worse than usual only because the scale is displayed logarithmically, and still the flare is so bright that it completely overexposes the images during its brightest phases).

TRACE also observed the Sun in the 1600Å channel, showing the intense radiation from the rapidly cooling loops above the solar surface, as shown in this (QuickTime; MotionJPEG/A compressed, Interlaced Odd; 11MB) 1600Å movie. This post-flare coronal rain shows the mixture of temperatures from some 10 million degrees to `only' some 100,000 degrees (a factor of 100!) in close proximity.

The TRACE movies show a lot of `noise' starting only minutes after the flare as a result of highly energetic protons and electrons hitting the detector, going right through the filters and even the spacecraft walls around the camera. These particles, that are causing a hazard to humans in space and can damage satellite electronics, also cause the "snow shower" seen in the LASCO and EIT images shown on this SOHO Hot Shot web page, and on the GOES proton-flux plot which measures the proton density near Earth: the high-energy proton level went up by a factor of about 1,000 shortly after the flare.

Filament activation
TRACE observed this small filament activation on 22 October 1999, in its 171Å passband (1 million degrees), shown in this (QuickTime; JPEG/A compressed; 0.7MB) 1-hr movie. The filament rises, exhibits what looks like a ring of hot material on a pedestal of cool and hot material wrapped around each other. The cool material then falls back onto the surface (compare with this event).
Post-flare loops in AR 9415 Flare-loop system in AR 9415
The top image shows Active Region 9415 on 10 April 2001 at 06:00 UT in 171Å (characteristic of emission from gas at 1 million Kelvin). The field of view is 232,000 by 174,000 km; the image was rotated over +120 degrees. These loops are the result of an X2.3 flare that started at 05:06 UT. The flare showed a classic double ribbon structure. As the ribbons spread apart with time the post-flare arcade of cooling, draining loops was formed, expanding with time. Courtesy: Dawn Myers. Click here for movies (BIG files!) of this event (courtesy Sam Freeland).

The bottom image shows the difference between the pre-flare phase (at 05:05 UT) in red and the post-flare cooling (at 08:38UT) in green; where the image is yellow, the emission hasn't changed much.

Sunspot loop evolution in AR 8667
On 17 and 18 August 1999, TRACE observed a filament destabilization and eruption in Active Region 8667, in the 195 Å passband (mostly sensitive to emission from gas at 1.5 million Kelvin). The composite image on the left shows two pairs of white-light (left) and 195 Å (right) images, taken almost 22 hours apart. The spot shows little evolution during the eruption, but the hot corona changes significantly. This evolution can be seen in the (QuickTime; JPEG/A compressed; 6.6MB) movie: First there is the flare and eruption, with some brigh ``moss'' ribbons lighting up northward of the main eruption, presumably showing the footpoints of hot loops or even where accelerated particles impact on the lower, denser atmosphere. After a data gap of one hour, high-arching cooling loops can be seen, as well as a sharp, bright line of moss moving into the spot; behind that front, loops are seen to cool into the range of temperatures visible in this 195 Å image. Successive generations of cooling loops are seen to move into the sunspot, and even into the darkest parts, the umbra.
A collage of TRACE images

1 April 2001:
TRACE celebrates its 3rd birthday

TRACE was launched on 2 April 1998, at 2:43 UT (1 April 1998 18:43 PST in California). Since then, it has taken approximately 5.8 million images (one exposure every 3.5 seconds, on average). The collage on the left contains some sample images that have appeared here before to capture some of the beauty of the solar atmosphere as it is seen by TRACE (shown in many publications around the world; see this list of examples of TRACE press coverage). Over 240 solar scientists in 22 countries around the world are working on TRACE data in order to distill understanding from all this, resulting in an impressive growing list of scientific publications (containing 181 entries today) that somehow or other are based on TRACE data. For a brief overview of the instrument, have a look at this slide set on the TRACE mission: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11.
X-point in AR9373
This triplet of images of Active Region 9373 (rotated counterclockwise over 90 degrees), was taken by TRACE in its 171 Å passband (sensitive mostly to emission from gas around 1 million degrees) on 20 March 2001. It shows evidence of a magnetic X point. But it's an odd sequence, in which the magnetic configuration is outlined by successive series of brightening loops. Look at this image: it outlines some of the coronal loops that are visible in one of the three TRACE exposures, and it repeats them in each panel. The kinked line is one that probably just misses the X point: coming from the left, it approaches a magnetic charge, then senses that there is another, more distant charge to connect to, and continues past the X point to connect to that charge using a nearly horizontal path to get there. This movie (1.5MB; QuickTime, JPEG compressed) shows the evolution over a 3-hr period.
Filament eruption and arcade
TRACE observed the activation/eruption of a filament in Active Region 8631 on 20 October 1999, around 05:50UT. The image on the right, taken around 05:57UT, shows the filament in mid-eruption, with bright, hot material (around 1.5 million degrees as seen in this 195Å image) and cool, absorbing material mixed in close proximity (the field of view is 640 by 480 pixels of 0.5 arcsec (~380 km) each). The (QuickTime; JPEG/A compressed; 3.7MB) movie shows the evolution of the eruption, from 05:50UT through 06:25UT. Notice that as the dark, cool filament material begins to rise, hot blobs form throughout and around the structure. The filament reaches its highest elevation around 06:00UT, after which the the field continues to reorganize itself, as material begins to cool and fall back. Notice the post-eruption arcade forming below the filament as the loops in question cool to temperatures for which this TRACE passband is most sensitive, i.e. around 1.5 million Kelvin.
M1.8 flare and loop oscillations in AR 9373

Shaken again

On 22 March 2001, a filament eruption in the regions trailing Action Region 9373 caused a rapid distortion of the coronal field that once again triggered oscillations in coronal loops, as seen in this QuickTime; JPEG/A compressed; 5.5MB) movie (shown at half the usual scale, with a field of view approximately 300,000 km high, rotated so that North is to the left). This phenomenon is very rare, at least we thought so until the day before this movie was taken (see the oscillations that were observed the day before); until then, only 2 other cases of oscillating loops were known. The image on the left shows the early phase of the eruption of the filament, at 04:33UT, observed in the 171 Å passband, sensitive to emission from gas at a temperature of approximately 1 million Kelvin.

Other TRACE images in this collection: Set 1, 2, 3, 4, 5, 6, 7, 8, 9, 10.

See also a collection of images related to the Sun, other cool stars, and solar-terrestrial effects


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