Which stars are called white dwarfs and what is their average density? Detailed answer

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Which stars are called white dwarfs and what is their average density? Detailed answer

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Which stars are called white dwarfs and what is their average density?

White dwarfs are stars with a low mass (no more than 1,4 solar masses) in the last stage of evolution. When such a star approaches the final cycle of thermonuclear reactions, its core collapses under its own weight, forming a superdense object of degenerated matter, consisting of atomic nuclei and electrons "packed" together. Gravitational collapse in white dwarfs is not infinite: as in black holes, it is stopped by a quantum effect associated with the pressure exerted by electrons.

These stars are characterized by an average surface temperature of 20-30 thousand degrees, which is why they are called not just dwarfs, but white dwarfs, while stars like the Sun (about 6000 degrees) are called yellow.

Since the mass of a white dwarf is comparable to the mass of the Sun, and the radius is comparable to the radius of the Earth, its density is very high: one cubic centimeter of the matter of a typical white dwarf weighs about a ton. A white dwarf is known (AC + 70 ° 8247), the average density of which is 36 tons per cubic centimeter!

Today, several thousand white dwarfs are known, which astronomers believe make up about 10 percent of all stars, but due to their low luminosity, they are difficult to detect.

The white dwarf is doomed to eventually go out, slowly cooling down and turning into a black dwarf. It seems that this process is so slow that from the beginning of the history of the universe until today, not a single black dwarf has yet formed.

Author: Kondrashov A.P.

Random interesting fact from the Great Encyclopedia:

How did medicine originate?

We need medicine to treat people from all sorts of diseases. You know that there are many ways to heal people. If you or your parents suddenly fall ill, you will call a doctor who will apply all his knowledge and experience to cure you with the help of science. But instead, you may use the remedy that your grandmother gave you, or try to cure a person with a spell, that is, apply the knowledge of traditional medicine.

Until medicine became a science, people used traditional medicine. Primitive people came up with a variety of, sometimes very strange causes of diseases, and therefore treated them based on magic and other means that seemed to be beneficial. They used heat and cold, bloodletting, massage, and medicinal herbs.

The medicine of Ancient Egypt, which was considered the most effective in antiquity, was based on spells. People used various ointments and drugs: honey, salt, cedar oil, brain, liver, heart and blood of various animals were often used as medicines. Sometimes these remedies helped, sometimes they didn't.

But scientific medicine originated only in Ancient Greece. More than 2000 years ago, a man named Hippocrates collected medical knowledge in one book, The Hippocratic Collections. It marked the beginning of scientific medicine, as it was based on the need to study the patient before making a diagnosis.

His book described the symptoms and course of diseases. For the first time, instead of relying on magic, treatment was carried out after examining the patient and studying the disease, as well as on the basis of the experience of predecessors. Modern medicine is based on the same principles.

Test your knowledge! Did you know...

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