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TESIS has photographed this years most powerful solar flare


TESIS has photographed this years most powerful solar flare

This years most powerful solar flare was photographed by TESIS telescopes in the southern hemisphere of the Sun on July 5th, 2009. The flash lasted 11 minutes from 10:07 until 10:18 Moscow time, reaching its peak at 10:13 Moscow time. At its highest point, the intensity of solar X-rays reached level 2.7 on the 5-point GOES scale.

The classification of flares is carried out by measuring the flow of solar X-rays in wavelengths ranging from 1 to 8 angstrom. All solar flares are divided into 5 classes according to these measurements depending on the maximum power of radiation emitted. These classes are denoted by letters of the Roman alphabet: A, B, C, M and X. Minimal class A0.0 is registered at 10 nanowatts/square metre of X-ray flow within the Earths orbit this figure then increases tenfold between each following category. To register in the highest category, the X-ray flow from the flare must increase to at least 100 000 nanowatts. Events of such power are unique and are only observed during maximal solar activity. Flashes with X-ray flow of more than one million nanowatts (up to class X17) were observed at the peak of the previous solar cycle at the end of October, 2003.

Although the observed flare is 100 times weaker in power when compared with these unique events, it is the biggest flare (among registered flares) for a very long time. The last time a class-C flare was registered was on December 11th, 2008, and it was several times weaker - the X-ray flow only reached level C1.4. Events more powerful than todays have not been observed on the Sun for over a year; since March 25th, 2008, when a level M1.7 flare occurred. A very slow increase in the Suns activity has been observed since around March, 2009. The first areas of activity, which make up the so-called northern belt a configuration, typical of the beginning of the new solar cycle started to form in the Suns northern hemisphere at the end of March after an extremely long three-year solar minimum. For two months, all the activity of the new solar cycle was connected with areas of this belt, including the first solar flares and coronal mass ejections of the year. Such domination of the Suns northern hemisphere over its southern hemisphere existed for about two months, until the end of May, when a southern belt of activity was formed. Thus, the magnetic configuration of the Sun became symmetrical once again following a short break.

The Suns southern belt of activity has existed for just over a month and is still much less developed than the northern belt. Nevertheless, this years largest solar flare occurred in the southern belt. Although it usually takes a long time to accumulate enough energy for a flare to occur, we are confident that this was not the case this time. The fact is that the active area, where the flare occurred, simply did not exist two days prior to the event. It appeared on the solar disk at midnight Moscow time on July 3rd. Therefore, either the flare energy was accumulated in magnetic fields before the area came to the surface, or the area is developing at unusually high speed - that characteristic for maximal activity. Observations of sunspots (the basic indicators of solar activity) support the latter conclusion. Their number in the area is increasing extremely fast: there were no sunspots in this area on July 3rd; there were seven sunspots on July 4th; and there were already fourteen sunspots on July 5th. The number of sunspots totalled 16 on July 6th. If there are no changes within the next few days, the large flare, which occurred yesterday, wont be the last this week.

Fortunately, a further increase in the Suns activity coincided with the beginning of the shadowless orbits of the CORONAS-PHOTON satellite, onboard which the observatory works. The space vehicles orbit plane will be turned to the Sun at an angle of approximately 90 degrees within the next two weeks. As a result, the vehicle will not enter the Earths shadow while it is rotating in orbit and will be able to observe the Sun uninterruptedly. This means that almost all of the solar events of these days will be captured by the TESIS telescopes. Three foreign space vehicles (the Japanese HINODE satellite and two NASA STEREO vehicles) will switch over to high observation frequency mode together at the beginning of the TESIS shadowless orbits.

The TESIS observatory
TESIS: tesis.lebedev.ru