The temperature of stars

When we talk about the temperatures of stars, it is meant that the surface temperature of stars, which can be measured. The surface temperature of the star is a black body temperature, which has the luminosity of the star. Increasing the temperature of the star to the center can only be obtained by calculation. The temperature of stars depends on the energy release and ranges between 3000 K and 50000 K, there are exceptions to 100000 K.

When we talk about the temperatures of stars, it is meant that the surface temperature of stars, which can be measured

Color star is a visible manifestation of their surface temperatures. Low temperature of stars corresponds to a reddish color, followed by all the visible colors, as is the case with a red-hot piece of iron in the forge (orange, yellow, white) to the highest temperatures of stars that appear to be bluish white.

Currently, the surface temperature of the star is measured by means of spectral analysis. The surface temperature of the Sun is 5760 K. The cold stars emit mostly in the red and infrared regions of the spectrum, such as Betelgeuse. Hot radiate mostly in the visible and ultraviolet regions of the spectrum, such as Vega.

There is a classification of stars in the radiation spectrum in the first place, the temperature of the upper surface of the shell. The differences in the spectra are caused by the difference in star their physical properties atmospheres, mainly the temperature and pressure. Type spectrum also depends on the presence of the interatomic magnetic and electric fields, differences in the chemical composition, the rotating star and other factors.

The continuous spectrum of radiation close to the stars of blackbody radiation at a temperature equal to the temperature of the upper surface of its shell, which can be estimated by Wien's displacement law, but for the distant stars, this method is not applicable due to the uneven absorption of light of different spectral regions of the interstellar medium. A more accurate method is optical spectroscopy, which allows to observe the spectra of stars of the absorption lines of varying intensity depending on the temperature of stars and their type.

At present, there are two spectral classification of stars: main (Harvard) and Hyeres based on the luminosity of stars. Harvard is the temperature classification is based on the form and the relative intensity of the absorption lines and emission spectra of stars. In Hyeres classification additional factor influencing the shape of the spectrum, is the density of the outer layers of the star, which depends in turn on its mass and density, that is, ultimately, on the luminosity. An additional advantage is the ability to Yerkes classification by type of spectrum to estimate its luminosity and, respectively, apparent magnitude - distance.

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