(ORDO NEWS) — We see innumerable stars in the sky. Many of them had already died by the time, as the light from them has reached the Earth. And some, on the contrary, was born. But how are stars born and how are they different?
A star is a dense accumulation of gas that is held in shape by the forces of gravitational attraction. Thermonuclear fusion reactions take place inside the stars, as a result of which a huge amount of energy is released. This energy is emitted in the form of photons of various energies and we perceive it as light.
A star is forming from a stellar cradle – a huge cluster of various kinds of molecules. Most of this cluster is usually hydrogen and helium. Over time, dense clumps of matter begin to appear in the cloud, which grows over time due to gravitational attraction.
The birth of a star can take hundreds of thousands of years and during this time various events can occur. For example, the cradles of different stars can collide with each other or pass through a dense gas cluster. This can cause the collapse of the formed clump and the process of star formation slows down. However, this could give rise to several new molecular clouds that could also give rise to a star.
With a large cloud size, a nascent star quickly gains mass and the process of thermonuclear fusion is “ignited” in it. However, there are also such objects that cannot gain enough mass for various reasons – brown dwarfs. They die quickly enough, leaving behind a cloud of gases, which over time can be reborn into a more massive star.
In addition to the brown ones, there are also white dwarfs. These are the “remnants” of a supernova explosion, in which there is practically no thermonuclear fusion. One of the most widespread classes in the Universe is red giants and supergiants. They have low temperatures in the atmosphere, but they glow brightly, especially in the infrared range.
Variable stars are also distinguished – objects whose luminosity periodically changes over time. Also in the Universe, as you know, there are neutron stars – one of the densest objects that balance on the verge of becoming a black hole. New, supernovae and hypernovae, which are formed during the collapse of stars, are distinguished into a separate class. In this case, the ejection of the outer layers of the atmosphere occurs and the luminosity of the object increases many times.
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