What Is a Double Star?

A binary star consists of two stars orbiting a common center. For one, the other is its companion. Compared to other stars, the position looks very close. The word Lianxing was coined by Friedrich Herschel in 1802. According to his definition, the binary star system is a system composed of two stars according to the law of attraction.

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A binary star consists of two stars orbiting a common center. For one, the other is its companion. Compared to other stars, the position looks very close. The word binstar was created by Friedrich

There are multiple types of stars, one star surrounds the other

If we use

Below we assume that we can observe the evolution of a pair of binary stars and make a field follow-up observation:

Initially, the mass of star A was about 2 to 3 solar masses, and the mass of star B was 1.5 solar masses. After that, just like the evolution process of a single star, a star with a larger mass evolved quickly. Star A first consumed a large amount of hydrogen. Its outer layer slowly expanded and quickly expanded into a red giant star. It keeps growing, and inside it has formed a white dwarf helium core with a radius of about a few tenths of the sun. When the outer shell of star A starts to enter the gravitational range of star B, the surface material of star A begins to leave the surface of star A and flows to the surface of star B by the gravity of star B. But because the two stars revolved around each other and the rotation of B star, the flowing material did not immediately land on the surface, but first formed a dish-shaped gas disk around B star with B rotation, and then gradually landed on the surface of B star. As a result, there has been a continuous transfer of material from Star A to Star B, which has accelerated the aging process of Star A and expanded at a faster rate, even engulfing the orbit of Star B. This process will last tens of thousands of years. After that, star A has used up all its remaining hydrogen, and its huge shell can stretch beyond a dozen solar radii, but in the end most of it will be absorbed by star B. At this moment, star A is basically made up of helium, only about one-fifth of the original mass remains, and star B has more than doubled its original mass. In this way, the mass contrast has changed significantly: Star A has become a dense white dwarf with a small mass, while Star B has absorbed a large part of the mass of Star A, its volume has increased a lot, and it has become a massive star in a binary star. A part of the original expanded shell around Star A gradually landed on the small white dwarf after losing its expansion force; while Star B is in its middle age and continues its normal star evolution. After that, the pair of binary stars continues to evolve. As before, the massive stars will evolve at a rapid rate, and after exhausting the hydrogen fuel near their cores, they begin to expand and enter the red giant phase. At this point, the strong gravity of Star A will slowly act on the material on the expanding surface of Star B, and the material will begin to flow quickly from the surface of Star B to Star A. As before, the liquid formed gas disks around Star A, and continued to land on the surface of Star A. In the future, due to the loss of a large amount of material, star B lacks fuel and rapidly ages and expands; star A may collapse into a neutron star or even a black hole due to the adsorption of a large amount of material. Star B will finally have a supernova explosion and end its life, throwing most of the body's mass into the universe, leaving a dense white dwarf or neutron star in its center.

Bizarre binary star

At night, people with better visions watch Kaiyang Star among the Big Dipper. In addition to seeing a second-class bright star, they also see a faint Kaiyang auxiliary star next to it. The naked eye sees a double star. . The angular distance between them is 12 , which is the two stars with the larger angular distance in the binary star. Kaiyang Double Star was the first double star discovered by human eyes in 1650. The two stars that make up a double star are called the twin stars. The brighter star is called the host star; the lighter star is called the companion star. The sub-stars of the double stars are inseparable and revolve around each other, and they rotate along orbits of varying ellipses. Binary stars are divided into physical binary stars and optical binary stars. Figure 3-8 Among the detected double stars, optical double stars are two stars that are not related to each other. After being projected onto the celestial sphere, they form a double star together. Such double stars have little research value. Physical binary stars are what we usually call binary stars, and they are divided into visual binary stars, spectroscopic binary stars and eclipse binary stars.

Visual binaries are binaries composed of two sub-stars that can be discerned with the naked eye or through photography through a telescope. Visually, the orbital radii of the double stars orbiting each other are relatively long, and the period of natural orbiting is also relatively long. Generally more than 5.7 years. The shortest period is 1.59 years, and the longest period can reach tens of thousands of years.

The distance between the two sub-stars of the spectroscopy binary star is closer than the above-mentioned visual binary star. Even through the telescope, the two stars cannot be distinguished with the naked eye or by photography. Such close-range binary stars can only be observed by spectroscopic methods. Any spectroscopic method is used to determine whether a celestial body's spectral line position changes, and it can be determined that it is a double star, which is called a spectroscopic double star. The period of the change of the spectral line position of the spectroscopy binaries is the period of the orbits of the binary stars. The eclipse double star is also called eclipse double star, also known as luminosity double star. Because the two sub-stars of this binary star revolve around each other, when the orbit and the line of sight of the binary star are almost on the same plane, they will cover each other and cause the phenomenon of eclipse and cause the brightness of the binary star to change. Eclipsing binary stars are also known as eclipsing stars (see the preceding eclipsing variable stars for details).

In the binary star system, there are two sub-stars that are very close to each other and exert influence on each other. There is also a material exchange between each other. The evolution of each sub-star is greatly affected by the other sub-star. . The well-known beta star (Lycene II) in Lyra is a eclipse variable star and a close binary star. If it is possible to take the spacecraft to the second stage of the platform, it is very interesting to watch its wonderful performance. You see, the two bright stars that make up the second stage orbit rapidly around each other, orbiting every 12.9 days. And a powerful stream of matter is constantly thrown from the host star. Some of these thrown out materials may go near the companion star to form the material around the star. Some may later leave the entire binary star system and fly into interstellar space. The companion mass of this binary star is greater than that of the host star. Due to the strong attraction of each other and the rapid rotation of the sub-stars, the host star is probably peach-shaped, and the companion star may be disc-shaped. This fascinating scene caught the attention of astronomers.

In the region near the sun (81.5 light years), the binary stars are about 40%. The proportion of binary stars in the stellar world is very large. There are more than 60,000 double stars in the list of visual double stars published in the 1960s.

The colors of the double stars are colorful, and the two sub-stars of the double stars are both competing. The binary star's host star is larger than the companion star and smaller than the companion star. Judging from the classification of binary stars, there are all kinds of sub-stars. Some sub-stars are explosive variable stars, some are pulsating variable stars, some are white dwarfs, some are neutron stars, and even black holes. Some binary stars are included in the polystars. Many star clusters include binary stars.

Double stars reveal to us some of the mysteries of the stellar world. The most important physical quantity of a celestial body is its mass. The mass of a single star (except the sun) cannot yet be measured directly, and the mass of each star can only be accurately measured through a dual star system. Because the two sub-stars of the close binary star have the physical properties of interaction, it provides very favorable research conditions for the density distribution, structure, and evolution of celestial bodies. Two stars born at the same time with the same mass and composition are called "identical twins" and are expected to have the same physical properties. These unexpected differences suggest that the two stars were developmentally separated from each other by hundreds of thousands of years. The consistency between the theoretical ages of each star in a binary star system was derived and used as a self-consistent verification of the stellar evolution model before the main star sequence, so this lack of age synchronization in Par 1802 indicates that Empirical verification has an accuracy limit of hundreds of thousands of years.