Looking at the star, which has warmed and illuminated our planet for billions of years, few of us realize that we have a working natural thermonuclear reactor. Such a formidable and frightening comparison is connected with the nature of the Sun, which by its origin and composition is a typical star of our galaxy. Despite the fact that the processes occurring on the Sun, can not be called life-giving, this star brings us life.
What is the sun?
Why is the Sun, a star resembling billions of others in the Milky Way galaxy, so interested in astrophysicists and nuclear scientists? The fact is that this is the closest star to us, thanks to which we can understand the essence of the processes that are raging in the Universe from the moment of its birth. Having studied the Sun, we will understand what the stars are, how they live and how this brilliant spectacle ends. Other stars, due to their significant distance from our solar system, cannot show us the peculiarities of their appearance.
Our star is the central object of the solar system, around which eight planets, asteroids and dwarf planets, comets and other space objects rotate in their orbits. The sun belongs to the G class stars in accordance with the Harvard classification. In accordance with the classification of Angelo Secchi the Sun, just like Arcturus and Capella, is a yellow dwarf of II class. Unlike other stars, located in dozens, hundreds of light years from our planet, our star is located almost next door. Earth is separated from the Sun 150 million km - a negligible distance compared with the enormous distances that prevail in the universe.
The closest star to the Sun, Proxima Centauri, the red dwarf star, is 4 light-years away. We are far from nebulae and star clusters, which are the most turbulent areas of the galaxy. Such an arrangement provides quiet movement of the Sun in its orbit for 14 billion years, since the Milky Way galaxy and our Universe as a whole were formed. The speed of the star in orbit around the galactic center is 200 km per second.
By earth standards, 150 million kilometers is a long distance. However, even at such a distance, we fully feel the heat that radiates from the sun. The light of our star comes to us for 8 seconds and continues to heat and illuminate our planet. It's all about the size of our star. Despite the fact that our star belongs to normal stars with an average mass, its mass exceeds 700 times the mass of all the celestial bodies of the Solar system. The size of the solar disk today is defined and amounts to 1 million 392 thousand 20 km. This is 109 times the diameter of the Earth.
The origin of the sun, its life and death
Our star was born together with other stars more than 4-5 billion years ago. The gas cloud, which was formed as a result of cosmic cataclysms of enormous scale, became the birth house for the Sun. According to one version, clouds of gas appeared as a result of the Big Bang, which shook space. In terms of its composition, gas and dust clouds consisted of 99% of hydrogen atoms. Only 1% came from helium atoms and other elements. The whole set of elements under the action of gravitational forces received the necessary impetus and began to tightly compress into one substance.
The faster the mass grew, the faster the rotational speed became. Atoms were combined to form large compounds, forming molecular hydrogen and helium. As a result of physical processes and rapid rotation, a spherical formation was formed in the center of the cloud. A protostar appeared - the oldest form, which precedes the subsequent formation of a full-fledged star. The initial amount of cosmic gas exceeded the current size of our solar system. In the future, under the influence of gravitational forces, stellar matter began to shrink tightly, increasing the mass of the future star.
Together with a decrease in the size of the protostar, the pressure inside the stellar substance increased. This in turn led to a rapid increase in the temperature inside the gas formation. High density and temperature of 100 million. Kelvin launched the process of thermonuclear fusion of hydrogen.
Thermonuclear reaction generates a huge amount of heat and light energy, which spreads from the inner regions of the Sun to its surface. Every second from its surface more than 4 million tons evaporate into open space. Given that our star has been around for more than one billion years and continues to shine without visible and significant changes, we can conclude that the hydrogen reserves of our Sun are enormous. When this reserve is exhausted, it remains only to guess, doing mathematical calculations. Judging by the calculations of scientists, the Sun will still warm and shine a dozen billion years, until the stocks of thermonuclear fuel run out.
As the intensity of thermonuclear processes dies out, the final phase of the star’s life begins. The star's density will decrease, but its size will increase significantly. Instead of a yellow dwarf, the Sun will become a Red Giant. Having reached this stage, our star will leave the main sequence and will calmly wait for his death. Mankind cannot wait for the final of this drama, since the gigantic Red Sun will destroy with its fire practically all life on our planet. The surface of a huge red disk can be heated up to a temperature of 5800 K. The radius of the Sun will become 250 times larger than the current values.
Gradually, the surface temperature will decrease, and the star will increase in size. Its luminosity will also increase noticeably, by 2,700 times the current brightness. The first to disappear are Mercury and Venus. Planet Earth inevitably in tens of billions of years will cease to exist. The atmosphere of the planet will disappear under the influence of the solar wind, the water will evaporate and the surface of the planet will turn into a hot stone block.
In this phase, our star will remain for several tens of millions of years. After the temperature in the center of the solar core reaches 100 million Kelvin, the process of burning helium and carbon will start. A new round of chain reactions finally exhaust the sun. The greatly reduced mass of the star will not be able to hold the outer shell, which pulsating thermonuclear processes will dispel in space. In place of a red giant, a planetary nebula forms, in the center of which the core of the former star, a white dwarf, will remain. In other words, in tens of billions of years our hospitable star will turn into a small dense and hot object the size of our planet. In this state, the star will remain for quite a long time, slowly dying and smoldering.
Structure and structure of the sun
The proximity of the Sun allows you to get an idea of its structure and structure, to obtain information about how this natural fusion reactor works and what processes take place in it. It will be interesting to disassemble the structure, which consists of the following components:
- core;
- radiant energy zone;
- convective zone;
- tachocline
Next, begin the layers of the solar atmosphere:
- photosphere;
- chromosphere;
- prominences.
The star is not a solid, due to the fact that we are dealing with a hot gas, tightly compressed into a spherical region. At such temperatures, the existence of any substance in solid form is physically impossible. The bright light and heat emitted by the sun are the result of the same processes that a person encountered when creating an atomic bomb. Those. matter under the influence of enormous pressure and high temperatures is converted into energy. The main fuel is hydrogen, which in the Sun is 73.5-75%, so the main source of heat is the process of thermonuclear fusion of hydrogen, concentrated mainly in the core, the central part of the star.
The solar core is approximately 0.2 solar radius. It is here that the main processes go, due to which the Sun lives and supplies the surrounding space with light and kinetic energy. The process of radiant energy transfer from the center of the star to the upper layers is carried out in the radiant transfer zone. Here, photons aspiring from the nucleus to the surface are mixed with particles of ionized gas (plasma). Due to this, energy is exchanged. In this part of the solar globe there is a special zone - the tachocline, which is responsible for the formation of the magnetic field of our star.
Then begins the most large-scale region of the Sun - the convective zone. This area is almost 2/3 of the solar diameter. Only the radius of the convective zone is almost equal to the diameter of our planet - 140 thousand kilometers. Convection is a process in which a dense and heated gas is evenly distributed over the entire internal volume of a star towards the surface, giving off heat to the next layers. This process occurs continuously and can be seen by observing the surface of the Sun with a powerful telescope.
On the border of the internal structure and atmosphere of the star is the photosphere - a thin, only 400 km deep, shell. That is what we see in our observations of the sun. The photosphere consists of granules and is heterogeneous in its structure. Dark spots are replaced by bright areas. Such heterogeneity is associated with different periods of cooling the surface of the sun. As for the invisible part of the spectrum of the surface of our luminary, in this case we are dealing with the chromosphere. This is a dense layer of the solar atmosphere, and can only be seen during a solar eclipse.
The most interesting solar objects for observation are prominences, which look like long fibers, and the solar corona. These formations are gigantic emissions of hydrogen. There are prominences and move along the surface of the Sun with a huge speed - 300 km / s. The temperature of these loops exceeds the mark of 10 thousand degrees. The solar corona is the outer layers of the atmosphere, which are several times larger than the diameter of the star itself. The exact boundary of the solar corona is not. Its visible border is only part of this great education.
The final stage of solar activity is the solar wind. This process is associated with the natural outflow of stellar matter through the outer layers into the surrounding space. The solar wind mainly consists of charged elementary particles - protons and electrons. Depending on the solar activity cycle, the solar wind speed may vary from 300 km per second to the mark of 1500 km / s. This substance is distributed throughout the solar system, affecting all the celestial bodies of our near space.
Other stars in the main sequence have approximately the same structure. Other celestial bodies that we see in the night sky may have a different structure. Differences can consist only in the mass of the star, which in this case is a key factor for stellar activity.
Features of our star
Like all normal stars, of which the majority in the Universe, the Sun is the main object of our planetary system. The huge mass of the star and its dimensions provide a balance of gravitational forces, providing an orderly movement of celestial bodies around it. At first glance, our star is nothing special. However, in recent years, a number of discoveries have been made that make it possible to assert the uniqueness of the sun. For example, the Sun produces an order of magnitude less radiation in the ultraviolet range than other stars of the same type. Another feature is the state of our star. The sun belongs to variable stars, but unlike its sisters in space, which vary in intensity and brightness of light, our star continues to shine with an even light.
It also releases a huge amount of energy, with only 48% of this amount visible. Invisible to the human eye infrared radiation accounts for 45% of the energy of the sun. Of all the enormous amounts of solar radiation, our planet receives absolutely crumbs, about half a billionth of a share, but this is enough to maintain the balance of the conditions created on Earth.
Conclusion
Estimating the data on the Sun obtained to date, it cannot be said that we thoroughly know the nature of our star. All ideas about the structure and structure of the Sun are based on mathematical and physical models created by man. Analysis of the processes occurring inside our star and on its surface allows us to find an explanation of the processes and phenomena that occur on our planet. The sun is not only a generator of energy that warms our planet, but also the most powerful source of radio emission and electromagnetic waves that affect the Earth’s biosphere. Any change in the activity of the Sun instantly reflects on the state of the Earth’s climate and our well-being.
