Scientists are getting closer to understanding the sun's atmosphere. We tell you how our closest star works

What do we know about the sun?

The sun is a star from the Milky Way galaxy, which is

red-hot, gaseous ball, constantlyradiating streams of energy. This is the only source of light and heat in our star-planetary system. Now the Sun is at the age of a yellow dwarf, according to the generally accepted classification of the types of luminaries in the universe. It is approximately 4.57 billion years old. The body is located 149.6 million km from the Earth.

Author: Isik Bender

The sun's temperature ranges from 5,778 K tosurfaces up to 15 700 000 K in the core. The sun is stable in its brightness, it is in 15% of the brightest stars in our galaxy. It emits less ultraviolet rays, but has a greater mass than similar stars.

What is the Sun made of?

According to its chemical composition, our luminary was nothingdoes not differ from other stars and contains: 74.5% hydrogen (by mass), 24.6% helium, less than 1% other substances (nitrogen, oxygen, carbon, nickel, iron, silicon, chromium, magnesium and other substances).

Sun granules. Author: NSO / AURA / NSF

Continuous nuclear reactions are taking place inside the core, converting hydrogen into helium. The absolute majority of the mass of the solar system - 99.87% - belongs to the sun.

At the very center of the body of our star is the core. It occupies a quarter of the Sun's radius. It is here that thermonuclear reactions "rage", generating visible radiation. Due to its huge size, the density of matter inside the luminary is enormous - 150 times more than the density of water.

Solar surface by level of glowis heterogeneous and has less bright areas called sunspots, the duration of which varies from a few days to several weeks. It should be noted that there are spots larger than the diameter of the Earth.

In addition, on the surface of the Sun are located:

  • Torches are areas of increased brightness, "brothers" of sunspots, often preceding or following their occurrence.
  • Granules, about a thousand kilometers in size, covering the entire photosphere and visible to the normal eye.
  • Supergranules, 35,000 km in size, also completely envelop the entire surface of the star. But they manifest themselves only through physical effects.

According to the hypothesis of Hans Bethe, inside the Sunreactions of conversion of hydrogen into helium with a large release of thermal energy are constantly occurring, a kind of hydrogen bomb operating for 5 billion years with a reserve for the same period.

How did the sun come into being?

There are various theories about the origin of the sun. The most popular of them claims that the luminary was formed from a gas and dust cloud resulting from a supernova. As evidence, the argument is given that there is a large amount of uranium and gold in the central body of our star system.

Author: NASA / SDO (AIA)

Another hypothesis traces a long chaintransformations: a comet from the periphery of the galaxy, then an ice planet, then a giant planet, then an infrared dwarf and now a yellow dwarf. Accumulating mass, the Sun, under the influence of gravitational forces, brought the core density to the start of thermonuclear reactions and the possibility of holding the atmosphere. Moreover, the attraction of a huge ball made it possible not to let go of even light gases: hydrogen and helium. True, from the surface of the luminary, they still evaporate into outer space.

Apparently, the Sun by its appearanceowes to the protostars of previous generations, since it contains a significant amount of metals. Its age is 4.5-4.75 billion years, and all this time it increases its brightness and temperature (flares up).

What do we know about the sun's atmosphere?

The Sun's atmosphere is largely determined by its composition. Recall that it contains the following elements:

  • hydrogen occupying 73% of the mass;
  • helium, which accounts for 25% of the weight;
  • other elements with a different concentration.

The sun's atmosphere is composed of several layers,one of them is the photosphere. It is represented by the visible surface that spews out the basic part of the radiation. The layer has a thickness of 100–400 km and a temperature value of 6 600 K (minimum). It is on this part that the determination of the size of the Sun takes place. The gas located here is rarefied, and the rate of rotation depends on the specific area. In the equatorial zone, one revolution occurs in 24 days, in the area of ​​the poles - in 30 days.

The solar atmosphere is also representedchromosphere. It is a shell surrounding the photosphere, which is 2,000 km thick. The upper boundary is characterized by constant hot emissions. This part is only visible during a total eclipse when it appears in red.

The last part of the Sun is the crown. It is characterized by the presence of prominences, energy eruptions. Their splash usually occurs within a radius of hundreds of thousands of kilometers, which provokes the emergence of the solar wind. The solar atmosphere in this area has a higher temperature - 1,000,000 K minimum, which can reach 2,000,000 K.

Image of the surface and crown of the Sun. Author: Hinode

In some areas, the value rises to 8-9thousand Kelvin. However, this part can only be seen during a solar eclipse. This area is characterized by a change in shape, which depends on the cycle of solar activity. At the maximum, its shape is round, at the minimum, it is elongated (along the equatorial part).

What has recently become known about the atmosphere?

New data that scientists have received is important forunderstanding how the solar atmosphere functions, as well as the solar wind - a constant stream of charged particles that also fall on the Earth.

Thanks to measurements and images of highpermits, which were made between 2009 and 2013 using HERSCHEL and data from the SOHO probe, scientists at the Turin Astrophysical Observatory and the Institute for Space Astrophysics in France believe that helium is unevenly distributed in the solar atmosphere.

Then NASA launched a research probe,whose task was to measure the content of genius in the solar atmosphere. Previous measurements boiled down to the fact that the ratio of helium to hydrogen was determined when they reached Earth.

Comparing the images of the probe with those imageswhich were obtained from the observatory of the European Space Agency, scientists were able to reveal the distribution of helium fluxes with changes in the solar wind near the Earth.

For example, in the equatorial region there is very little of it,and much more in mid-latitude regions. According to the researchers, these discrepancies may be related to the Sun's magnetic field and the speed of the solar wind in its corona, which can change.

Scientists measure the amount of helium in the solar atmosphere for the first time thanks to HERSCHEL probe data

In the future, scientists will continue to study the Sun's atmosphere with the Solar Orbiter, an automated spacecraft designed specifically to observe the Sun.

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