Solar flare

A solar flare is a structure of increased radiation in the chromosphere of the Sun, which is powered by magnetic energy. As chromospheric flare or eruption is called simple plasma - magnetic arches. If there is a reorganization of the arches, which leads to detachment of plasma tubes, one observes an increased mass ejection. Coronal mass ejection names for this are (CME ) or eruptive prominence, associated Teilchenstürme solar storm, proton showers, Solarkosmischer -ray burst (English Solar Cosmic Ray Event ) or SEP ( Solar Energetic Particles English ).

The particles of a coronal mass ejection interact with the solar wind and the interplanetary magnetic field. Fast particles are decelerated to the speed of the solar wind, slow speeds. There is a formation of a large shock front, which is responsible for the acceleration of the particles, in particular protons to energies above 10 MeV. The process of acceleration is called SPE ( Solar Particle Event english, also solar proton event ).

Depending on the author and age of the publications vary the boundaries of the designations.


The duration of the flares is proportional to the extent of the eruption area. The average lifetime is about 10 to 90 minutes, wherein, after a rapid increase in the brightness of a slow decay occurs. Flares occur in regions of the Sun where sunspots and solar flares also show up. Per day, 5 to 10 flares are observed at normal solar activity.

Larger flares may take up to 1 ‰ of the sun's surface or ten times the earth's surface. They are observed in spectroheliograms of the hydrogen and at the edge of the solar disc bulge as the chromosphere into the corona, usually in conjunction with Masseauswürfen (CME, prominences ).

Flares are classified according to their logarithmic X-ray energy into classes A, B, C, M and X. The intensity within a class is defined with a value from 1.0 to 9.9. Reaches the value of 10.0, it is presented to the next class. In class X, values ​​greater than 10 are possible. The classification results from the flow of X-ray radiation emitted by the sun, and that for the range of 0.1 to 0.8 nm ( 1.55 to 12.4 keV). The class A goes from 10-8 to 10-7 watts per square meter, while the X class starts from 10-4 watts per square meter.

An absorption spectrum of a Flaregebiets typically shows in addition to hydrogen and helium, and calcium. The regions amplified send out short-wave radiation in the ultraviolet and X-ray range as well as protons, electrons, and ions. On Earth, this causes disturbances in the ionosphere with corresponding impairments of the radio traffic.

The particles can result in penetrating the earth's atmosphere to magnetic storms. From Ionosphärenstürmen is when slowly cause visible at night auroras in the auroral zones penetrating particles and it comes through strongly fluctuating electric current to geomagnetic disturbances. In proton storms the fast solar protons penetrate into the polar caps, sometimes in mid-latitudes up to heights of 30 km, and increase the electron density and adsorption of short waves.


The origin of the flares can be attributed to electromagnetic processes inside the sun. The sun is composed of a plasma of negative electrons and positive ions, is maintained by convection in constant motion. The electrons have a higher velocity than the ion due to its lower mass. Flowing an electrical current which induces a magnetic field. Partial bulge while magnetic hoses to the outside. Contact between the loops on rotation, the magnetic field lines close shortly and there will be a reconnection. The magnetic reconnection is a physical phenomenon in which the structure of a magnetic field changes abruptly and large amounts of energy are released. It is probably responsible for the solar flare. Due to the opposite orientation of the magnetic field, the loop continues catapulted the enclosed material.