What is a star, each of us knows from childhood. This is a celestial body that we see as a small luminous point in the night sky. In fact, all the stars are huge balls made of hot gases. They include ninety percent hydrogen, a little less than ten percent helium, and the rest are various impurities. In the center of the ball, the temperature is about six million degrees. This value corresponds to the limit that allows the thermonuclear reaction to proceed freely . During this chemical process, hydrogen is converted to helium. As a result, a huge amount of thermal energy is released, which is transmitted into outer space in the form of bright light.
What is a star? It is the same as the sun. At the same time, small stars are ten times smaller than our star, and large stars exceed its parameters by one hundred and fifty times.
Often in response to a question about what a star is, astronomers call these fireballs the main bodies located in the universe. The thing is that it is in them that the bulk of the luminous substance that can be found in outer space is contained.
Stars in the sky, which we can observe through a telescope, are often surrounded by nebulae that have different shapes. These neoplasms, which are clouds of gas and dust, can begin the compaction process at any time. At the same time, they will be compressed into a figure in the form of a ball and warmed up to a significant temperature. When the thermal regime reaches six million degrees, thermonuclear interaction will begin, that is, a new celestial body will form.
Scientists have identified various types of stars. They are divided by their mass and luminosity. Separation is also possible according to the stages of the evolutionary process.
The class, which contains stars in which the radiated energy is balanced with the energy of thermonuclear reactions, subdivides them according to the form of glow into:
- white;
- blue;
- white and blue;
- yellow;
- white and yellow;
- red;
- orange.
The maximum temperature is observed in stars with a blue glow, the minimum - in red. Our Sun belongs to the yellow species of luminaries. His age exceeds four and a half billion years. The core temperature, which scientists calculated, is 13.5 million K, and the crown is 1.5 million K.
What is a giant star? To this kind of luminaries are fiery bodies having mass and diameters superior to the Sun by several tens of thousands of times. Giants emitting a red glow are at a certain evolutionary stage. The diameter of the star increases by the time hydrogen is completely burned out in its core. At the same time, the combustion temperature of gases decreases and a red glow spreads over millions of kilometers. The giant stars include VV Cepheus A, VY Canis Major, KW Sagittarius and many others.
Among the heavenly bodies and dwarfs. Their diameter is much smaller than the size of our sun. There are dwarfs:
- white (cooling down);
- yellow (similar to the sun);
- brown (often considered as planets);
- red (relatively cold);
- black (completely cooled and lifeless).
There is also a kind of variable stars. These luminaries are bodies that at least once in the entire history of observation have changed their brilliance and development dynamics. These include:
- rotating;
- pulsating;
- eruptive;
- other unstable, new, as well as difficult to predict luminaries.
Such stars, which are represented mainly by bright blue and hypernovae, are very specific and have not been studied much. Each of them is the result of the resistance of matter and the work of gravitational forces.
The stars also include black holes. It is believed that this is one of the stages of the evolutionary process of celestial bodies. Such a body does not emit glow, however, certain of its characteristics put it on a par with the stars.