Want to give the solar temperature, can't the airdrop individual temperature work?

The following article comes from WeChat public account: origin reading, author Lu Changhai

The sun is very hot is the fact that everyone on the earth knows. But how "heat" is it, it is not enough to rely on adjectives, and the temperature is the last word.

Many astronomers want to know the temperature of the sun. In fact, a early motivation to determine the number of sun numbers is to calculate the temperature of the sun.

It is a pity that although people's early measured solar constant and the light degree of sunlight calculated from this is not far from the modern value (at least in the same order of order), the theoretical basis that linked them with temperature has always been vacant. This has always been vacant. This has always been vacant. The "vacuum" of the theory leads to a chaotic situation.

The method of calculating temperature can be described as a variety of, from the "Heat-Ray" (Heat-Ray "to the law of Newton's Law of Cooling, which is not applicable. As far as the calculation results are concerned, from more than 1,000 degrees to millions of degrees, there are differences in the sky.

In order to encourage reliable research, in 1876, in 1876, the Paris Academy of Sciences specially set up a prize for calculating the solar temperature. Unfortunately It was obtained with a "unreliable" 1,500 to 2500 ° C.

Joseph Stefan

The theoretical basis for the calculation of the sun temperature was not first obtained by the Austrian physicist Joseph Stefan (1835-1893) from the experimental data. 1844-1906) launched from thermodynamics.

Ludwig Boltzmann (Ludwig Boltzmann)

They found that a black body's radiation power (that is, the energy radiated per second) on the unit area was proportional to the four prescriptions of the absolute temperature. This law is now called Stefan-Boltzmann Law, and the proportion coefficient is called Stefan-Boltzmann Constant. Under the international unit system, the value of the constant constant of Stelsman is 5.67 × 10-8.

Although the Law of Sterfan-Boltzmann is aimed at black body, most of the star radiation is closer to black radiation, so this law is similar to star radiation. With this law, the surface temperature of the sun has theoretical foundation.

The calculation method is very simple: (under absolute temperature standard) Four squares on the surface temperature on the Sterfan-Boltzmann constant is the radiation power per square meter on the surface of the sun, and the surface area of ​​the sun Power (that is, the total energy radiated per second), that is, the light of my sun.

It is not difficult to obtain -the surface temperature of the sun (exactly the valid temperature of the light ball layer of the light ball) is about 5800K (K is the temperature unit of the absolute temperature standard, and the 0 ° C of the Celsius temperature is about 273K).

In addition to the above method, we introduce a method that is more interesting although it is rough.

In the above calculation, in addition to the Law of Sterfan-Boltzmann, you also need to know the value of the Sterfan-Boltzmann constant, as well as the light and light of the sun.

But in fact, as long as the four-time relationship given by the Stanfan-Boltzmann Law, even if you do not know the size of the constant constant of Sterfan, or even the light of the sun, we can still calculate The surface temperature of the sun.

The method is very simple: we know that the average temperature of the earth surface is about 290k (ie 17 ° C -this is a dual average of the region and time). Although it is easy to be ignored, the planet of such temperature will also radiate the energy outward radiation energy. And this energy can also be described by the Law of Sterfan-Bolzmann. Because the energy on the earth is not like the sun, the energy on the earth is mainly from the sun. In addition to the sun, the energy accepted on the earth also contributed from the inside of the earth. However, the average power of the latter is only 0.06 watts/m 2, and less than one ten thousandth of the sunlight energy can be ignored in our calculations.

The earth can maintain the current surface temperature, indicating that the energy it radiated outward is basically equal to the sunlight it received. With this relationship, we can calculate the surface temperature of the sun.

The calculation process is very simple. Readers may wish to try it by themselves. You will find that Star Fan-Bolzman's constant will automatically disappear during the calculation process. The calculation results are about 6000K. Not far.

The interest of this method is that it uses the temperature of the planet to reflect the temperature of the star. But more interesting is that in turn, we can also calculate the temperature of the planet at a certain distance from the temperature of the star. This feature is often used by astronomers to estimate the position and width of the so -called habitable zone that may raise life around the stars.

Of course, the limitations of this calculation are very large. For example, it requires that there are things that can make the temperature uniformly in the planet's existence of water and atmosphere, but also require the atmosphere to contain greenhouse effect gas as greenhouse effects. Before the end of the game, we sent another small red envelope -introduce the spectral type of the sun.

Shortly after the emergence of the Law of Sterfan-Bolzmann, German physicist Wilhelm Wien (1864-1928) proved a law with thermodynamic method called Wien 'S Displacement Law.

Wilhelm Wien

This law shows that the higher the surface temperature, the more the spectrum distribution is shifted in the short wave direction, and it is shifted in the blue direction in the color.

Using this feature, astronomers divide the stars into seven categories according to the characteristics of the spectrum, marked them as O, B, A, F, G, K, M.

Scholar spectrum schematic diagram

Among them, the O -type celestial body is blue with the highest surface temperature. It is above 33000K. The M -type celestial body is red with the lowest surface temperature, below 3700K.

The yellow celestial bodies like the sun are G -type, and the surface temperature is between 5200 and 6000K. Among each type, ten sub -types are divided into the order of temperature from high to low, and Arabic numerals 0 to 9 are used to indicate that 0 indicates the highest temperature and 9 indicates the lowest temperature.

The spectrum type of the sun is G2, which is considered higher in the G type. In some literature, the type of spectrum of the sun is marked as G2ⅴ. The "ⅴ" here is not the English letter "ⅴ", but the "5" of the Roman numerals. It comes from another classification rules. It is the main sequence star (that is, the star of the adult).

Wenyuan: "The Story of the Sun: The Story of the Sun"

Author: Lu Changhai

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Edit: Zhang Runxin

This article is reprinted from WeChat public account: Original Reading Author: Lu Changhai

Reprinted content only represents the author's point of view

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It does not represent the high energy office of the Chinese Academy of Sciences

Edit: Liu Yi

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