Hua Feng slowly understood that according to Wien's law, the color of a star is directly related to its temperature. So astronomers can know the nature of a star from its spectrum.

As a result, astronomers have been classifying stars by spectral type since the 19th century based on the absorption lines of their spectra. Astrophysics was developed from this.

According to the spectrum of stars, stars can be divided into several types, from the O-type with the highest temperature to the M-type with low temperature where the molecules can be present in the star's atmosphere. The most important type is "Oh, Be A Fi."

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l" to "guy"), and there are many other forms of mantra memory), and there are special classifications of various rare spectra, the more common of which are L and T, which are suitable for stars and brown dwarfs that are cooler and less massive than M-type. Each type is marked with the number 0 to 9 from high to low temperature, and then subdivided into 10 subcategories. This classification is quite consistent with high and low temperatures, but no stars have yet been classified as O0 and O1, which have the hottest.

On the other hand, stars also have a "photometric effect", a two-dimensional taxonomy corresponding to the size of the star, from 0 (supergiant) via III (giant) to V (dwarf) and VII (white dwarf). Most stars are ordinary stars that burn hydrogen, known as main-sequence stars. When plotting the Hérault diagram with spectral correspondence to absolute magnitude, these stars are all distributed within a narrow diagonal line.

The type of Sun is G2V (yellow dwarf), and it is a star of average size and temperature. The Sun is used as a typical specimen of stars, not because it is special, but because it is the closest star to us, and many of the characteristics of other stars can be compared with the Sun as a unit.

Each star needs to be given a unique name so that it can be easily studied and identified. Since the Warring States Period, China has named stars that can be discerned by the naked eye, or after the stars in which they are located (including Sanyuan and Twenty-eight Nakshatras), such as Tianguan Xing, Beihe Er, Antares II, etc., or according to legends, such as Vega Star (Weaver Girl I), Cowherd Star (Hegu II), Old Man Star, etc., forming an independent system that is not rigorous.

The concept of Western constellations has been around since the Babylonian period, when ancient stargazers imagined different shapes by combining the more significant stars with specific natural or mythological objects. The 12 constellations located in the zodiac became the basis for astrology, and many apparent individual stars were given their own names, especially in Arabic and Latin.

And some of the constellations and the sun have their own overall mythology, which are considered to be the spirits of the dead or gods, such as the Great Tomb Five, which represents the gorgony Medusa.

By the time of the ancient Greeks, it was known that some of the stars were planets (meaning "wanderers") representing a variety of important gods, such as Mercury, Venus, Mars, Jupiter, and Saturn (Uranus and Neptune, although also gods in Greek and Roman mythology, were dimly luminous and therefore not discovered by the ancients, and their names were given by astronomers later). ）。

Around the 1600s, the names of constellations, ranges, and stars were still named by the regions themselves. In 1603, the German astronomer Johann Bayer created the Bayer nomenclature, which combines the Greek alphabet sequence with the constellations, to name each star in the constellation. Then the English astronomer John Franstede invented the nomenclature of the numeral system, which is known as the Fransteide nomenclature. Since then, many other systematic catalogs have been created.

In the West, in 1603 the German amateur astronomer Bayer suggested that the stars in each constellation should be represented in order from light to dark, with the name of the constellation plus a Greek alphabet. For example, Orion α (Betelgeuse) and Orion β (Betelgeuse) (but in fact Orion β brighter than Orion α). If the number of stars in a constellation exceeds 24 Greek letters, the lowercase Latin letters (a, b, c...) are used in succession. ), which is still not enough to use the uppercase Latin letters (A, B, C...) ）。

Franstede, the first director of the British Observatory, created a numerical nomenclature that numbered the stars visible to the naked eye in a constellation from west to east and from north to south.

The only institution recognized by the scientific community to be able to name a star or celestial body is the International Astronomical Union. Many private companies (e.g., "I

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y) sells the names of stars, but these names are neither recognized by the scientific community nor used by anyone other than the buyers, and there are many organizations that fraudulently claim to be astronomical institutions to trick ignorant people into buying the names of stars.

Hubble telescope photographs of Sirius and its companions, with a long history of human observation of stars. Ancient Egypt used the appearance of Sirius on the eastern horizon to herald the day of the flooding of the Nile.

The Shang Dynasty of China set up special officials to observe the appearance of fires in the east, and determined the time of the beginning of the year, which was listed in the divination along with the sowing and harvesting of crops. The navigators of the Ming Dynasty in China used the Nine Stars of Navigation to determine the direction. The U.S. Apollo 11 spacecraft has an optical locator that uses stars to determine position.

The volume of a star can be measured by interferometry and lunar occultation to determine the angular diameter of the star, thus finding the volume.

The mass of a star can be measured using Kepler's third law or the relationship between stellar luminosity and mass.

Stars age and expand into red giants swallowing orbital planets: or the future home of the Earth

On August 24, 2012, according to foreign media reports, an international research team composed of scientists from the United States, Poland and Spain and other countries found for the first time evidence that an aging star has engulfed its planet.

On March 24, 2015, Yasuo Fukui, a professor at Nagoya University in Japan, and others announced that they had observed a huge star that was born from the collision of two high-density gas clouds, one large and one small. This is the first time that scientists have discovered a giant star that has just formed, and it will help to understand the mechanism of the formation of giant stars.

Astronomers have always had different estimates of the number of stars in the universe. One of the most famous claims is a hypothesis put forward by the American astronomer Carl Sagan in his book "A Hundred Billion of Billions" that there are 100 billion galaxies in the universe, each with 100 billion stars.

Based on this, astronomers further speculate that the number of stars in each galaxy is about 100 billion trillion times a trillion times. American astronomer Peter Van Dokun and astrophysicist Charlie Conroy analyzed the intensity of light from galaxies and concluded that it was about 3X10.

Previously, most scientists believed that in the early days of star formation, it was surrounded by a circle of saucer-shaped cosmic debris composed of cosmic dust and gas, and later, it took millions of years for this disk-shaped cosmic debris to gradually form planets orbiting the star.

However, a study in the November 28, 2002 issue of the journal Science reported that these massive saucer-shaped cosmic debris would split apart after a few rotations around the star, and the ruptured material would quickly coalesce together and pull the gas through, forming a huge planet with gas around the periphery like Jupiter.

Scientists in the United States and Canada have discovered that the formation of Jupiteran planets goes through such early stages, otherwise, cosmic gas and dust are pulled away and dissipated by the gravitational pull from nearby stars.

And the study of Jupiteroids outside the solar system also confirms this theory.

In the article "A New View on the Structure and Evolution of the Solar System", Mr. Han Xinggao further pointed out that the great planets of the solar system are synthesized by the combination of positive and negative dust materials in the two spiral arms of the Sun after they meet. As the two spiral arms entangle, approach and meet with the rotation of the sun, the material of the positive and negative spiral arms collides, first forming the core of the celestial body, and then continuing to absorb the material to grow and grow like a snowball, a planet is born.

Because the spiral arm will inevitably entangle and approach with the rotation of the sun, the planet formed by the collision first is closer to the sun, and the planet formed by the collision is farther away from the sun as the spiral arm continues to extend and collide again, and so on, the closer the planet of the solar system is formed, the older it is.

Hubble's detailed images of spiral galaxies such as M51 and M100 show spiral arms entangled, approaching, and colliding to form planets, while Hubble's images of supernovae SN1987A triple-rings show a microcosm of the early stages of planet formation.

Under the condition that their original kinetic energy and the internal magnetic field that determines the potential energy are kept within a certain energy level range, the large planets of the solar system each have their relatively stable energy level orbits, and generally do not cross and collide.

Under the condition that the magnetic field of the major planets remains within a certain range, the orbital radius of the major planets changes with the activity of the sun, and the orbital radius is in the shrinking stage as the solar activity decreases. The oldest planet in the solar system closest to the Sun is depleted by the depletion of the internal troposphere, the magnetic field weakens, the gravitational pull to see the Sun decreases, and the orbit rises (rather than descends in the direction of the Sun).

In the process of ascension, it is possible to be captured by a large asteroid close to orbit and become a satellite, but due to insufficient gravity, it generally does not collide with the asteroid until it finally explodes and disintegrates near the asteroid belt due to the decrease in internal gravity insufficient to maintain the union state of the celestial bodies, and becomes a member of the asteroid belt.

The asteroid belt is the graveyard formed after the disintegration of large planets. The ancient planets in the solar system eventually found their home here. He pointed out in "The Explanation of the Origin and Fate of the Moon in the Unified Electromagnetic Field Theory" that the Moon is likely to be a planet in the solar system older than Mercury, and may have been captured as a moon of Venus due to the depletion of the internal troposphere radiation, the weakening of the magnetic field, and the increase of orbit.

Despite being very close to Earth, there is no possibility of a collision with Earth, and it continues to move away from Earth at a rate of a few centimeters per year, and it is possible that it will become a satellite of Mars in the future, (some of the moons of Mars may be older than Mars, and they may all be captured in this way from the inside out) or finally explode and disintegrate near the asteroid belt.

The end result of the ascenting of these planets is that they will explode and disintegrate when the potential energy is reduced to the quantum limit in a certain electromagnetic space environment. This is how the asteroid belt between Mars and Jupiter was formed, the home of the early planets. The final graves of the current planets of Mercury, Venus, and the existing inland planets, including Earth and Mars, are all here. Of course, as the state of the solar system allows, new planets will be created and added to the planetary ranks.