Star

Star – Broadly speaking, stars are self-luminous cosmic objects that are mostly composed of plasma that is heated by nuclear reactions occurring within them.
The main condition for a star’s existence is a balance between the weight of the overlying layers and the pressure (see Radiation Pressure) of the electromagnetic radiation that results from thermonuclear reactions in its interior.
Also, stars are other objects that are not included in the list presented above. These include such entities as neutron stars and white dwarfs (see Stars, white dwarfs). They are the result of the formation at the last stage of evolution (see Stars, evolution) of some stars, when nuclear reactions in them have ceased. At the same time, these cosmic bodies are in a state of equilibrium. This is facilitated by the correspondence between the weight of the overlying layers and the gravity of the matter below them.
As stars are also called point luminaries on the celestial sphere. Scientists in the field of astronomy, navigation and sometimes, for example, when “covering stars with solar system bodies”, planetologists are not interested in the physical parameters of stars as space objects.
It is worth mentioning that recently, attempts to observe stars as large and extended objects rather than point objects, such as the star Betelgeuse, an alpha in the constellation of Orion, have become successful.