By solar activity is meant a combination of unsteady phenomena that are in dynamics, and various active formations that arise in the atmosphere of the sun. One of the manifestations of its activity is the appearance in the magnetic field of the solar atmosphere of specific fibers, namely, plasma formations. When they become visible at the edge of the solar disk, they are called prominences.
Prominences - what is it?
The first mention of the fact that during the period of the total eclipse of the Sun there was the appearance of unusual formations appeared in 1185, and a detailed study of them began in 1842. Subsequently, they were called prominences (protubero), which in Latin means "swell."
Today, thanks to numerous studies, it is known that a prominence is a formation from the solar plasma, which has colossal dimensions. These gigantic emissions rise above the surface of the Sun along the lines of force of its magnetic field and are held there for a certain time. Some of them can “hang” in the space around the sun sometimes up to several months, practically without changing their original shape.
Prominences in essence
Despite the fact that science has been studying these unusual formations for a long time, there is no clear and complete theory explaining their diversity and the various phenomena associated with them. In fact, the prominences of nature are dark fibers that are clearly visible in the chromosphere of the Sun. Their structure is denser and colder than the surrounding plasma, and the chemical set of elements corresponds to the composition of the layer forming them. Nevertheless, their internal physical state is such that the spectrum of some prominences is oversaturated with hydrogen lines, and others with various metals. The duration of their existence indicates that their substance is held by magnetic forces.
How are prominences manifested?
Solar prominences look like bright formations protruding along the edges of the solar disk. Arising against its background, they have a darker color, which is due to lower than the surrounding substance, the temperature of their plasma.
Against the background of a hot crown, a prominence is a dense and cold formation. Rising from the surface of the Sun, it partially discards its substance, and then it descends and disappears. Some of them are present in the crown for months, while others, moving at high speed, do not disappear for several weeks. Individual specimens, which have tremendous speed, suddenly explode.
What sizes are prominences?
Prominences on the Sun amaze with their extraordinary size. Typical representatives of these formations reach a height of up to 40 thousand kilometers, while their width can be about 200 thousand kilometers. There are also such emissions, the height of which is 800 thousand kilometers. Scientists have repeatedly recorded such champions, the size of which exceeded 3 million kilometers. The eruption of one of such enormous prominences, which shot up, arched by a horseshoe, was observed from the spacecraft for 30 hours in August 2010.
What are prominences?
These formations are quite diverse. In their appearance and speed, prominences on the Sun are divided into:
- calm, characterized by slow movement and an almost imperceptible change in shape, they can exist for several weeks or months;
- active, which are characterized by the speed of movement of the substance flow and the existence time from several minutes to tens of hours;
- loop-shaped (coronal), as a rule, arise in the form of small clouds, which eventually merge into one large cloud that exists for several hours;
- eruptive (or soaring) resemble huge fountains that can erupt very quickly and change their shape, and then quickly disappear.
Depending on their form, as well as on how the matter itself moves in them, they are classified into three types:
- Formations in the form of a stream of smoke or clouds, capable of spiraling to a considerable height.
- Prominences in the form of curved jets and knots that begin and end on a sunny surface. As a rule, rising along magnetic lines of force, at high altitude, they begin to fade.
- Large formations in the form of a tree or shrub. Clumps of their substance move randomly, while having a velocity that does not exceed several tens of km / s.
How to observe prominences?
Prominence is a manifestation of the activity of the Sun. It can be observed during a total solar eclipse, although it happens quite rarely. That is why scientists have designed spectral instruments to recreate artificial eclipses. Such telescopes made of a special kind of glass, devoid of microbubbles, are equipped with a black disk that imitates the moon. In the process of observing the Sun, he slowly floats on it, as a result of which the instruments see light coming only from its crown.
An amazing picture opens before the eyes of observers - the dance of prominences in the Sun. Beyond the edge of the makeshift moon you can clearly see the protrusions of a complex shape of bright pink color, similar to flames or huge clouds bursting from the upper layers of the solar disk.
Within the peak of 11-year-old activity of the Sun, coronal arcuate prominences can be observed. This is a rare phenomenon of indescribable beauty - formations in the form of a huge cloud, from the edges of which jets descend, appear in the corona of the Sun over its chromosphere.
For astronomers, the phenomena occurring in the solar corona have long remained mysterious. Prominence ... This word was associated with a secret held by a star named the Sun. And only in our time, thanks to satellites and space stations, most of these secrets were revealed.
Mankind will have to make many more great discoveries both in the unknown universe and in our solar system.