How many stars are there in Taurus?

Taurus is mainly composed of two nights, the Pleiades and two stars, Celestial and Apocalypse.

Taurus is a constellation that appears in the south of the sky on winter nights. The symbol of Taurus symbolizes the bull head. Its guardian star is Venus and its patron saint is Venus, the goddess of love and beauty. In the sky not far from the northwest of Orion, there is a very bright 0.86m star (the first 13 of all the stars), which is the alpha star of Taurus, which was called Bisu V in ancient China.

Taurus is also one of the famous zodiac signs, and Bi Suwu is located near the zodiac. It is about 90 degrees away from the four bright stars near the ecliptic, such as Xuanyuan XIV of Leo, Antares of Scorpio and Beiluoshimen of Nanyu. They are called the "four heavenly kings" of the zodiac.

An irregular variable star, whose spectral type is G ~ M and the typical star is Taurus T, was first discovered by Joey in 1945. Taurus T-variables are closely related to diffuse nebulae, which appear in groups and often constitute the main members of the T-variables Association. It is estimated that there are about12,000 T-deformed stars in the parsec around the sun, and the total number in the whole galaxy is10,000,000. All these variables have aperiodic irregular light changes, or fast light changes are superimposed on long-term slow light changes. The maximum amplitude is 5 magnitude, generally 1 ~ 2 magnitude. In recent years, it has also been found that there is light variation in infrared band. Their spectra are superimposed on a night photosphere with a series of emission lines. The strongest emission lines are Balmer line, H line and K line of calcium ion Ca Ⅱ. Emission lines such as ionized iron Fe ⅱ, ionized titanium Ti ⅱ, neutral iron Fe ⅰ and neutral calcium Ca ⅰ and low excitation metal atomic lines often appear. There are overlapping continuous emission spectral regions in the blue-violet region. In some cases, this continuous emission is so intense that the absorption spectrum of the photosphere is completely submerged. In the high dispersion spectra of some bright T stars in Taurus, most absorption lines are broadened. It means that their speed is very high. There are quite a few Taurus T stars in Cygnus with P-shaped starlight bricks, that is, the absorption line appears at the short-wave end of the strong emission line profile, which indicates that they throw matter outward. The mass loss rate is estimated as 10 ~ 10 solar mass per year. A few T-stars in Taurus have the spectrum of anti-Cygnus P-stars, which indicates that there is the phenomenon of matter falling inward. The polarization of some T stars in Taurus is as high as 12%. The lithium abundance of T star in Taurus is about two orders of magnitude higher than that in the solar atmosphere, and there is infrared color residue. Radio emission of T star in Taurus was measured. At present, T star in Taurus is a kind of preorder star in gravitational contraction stage.

At first, American astronomer Joy called 1 1 variable star a variable star with mixed emission lines in the 1945 nebula "Taurus T variable star". By 1962, a brighter 126 Taurus T variable has been found. These variable stars are usually shrouded in diffuse nebulae, with low surface temperature and mostly of late spectral type. Except for a few, the luminosity changes irregularly, and the light changes regularly from a few tenths of stars to a few stars, often accompanied by Hα emission line and H K line of calcium ions. Spectral analysis shows that the T-variable star in Taurus has the phenomenon of material outflow, and the eruption speed varies from 225 km to 425 km per second, and it changes with time.

In the H-R diagram, the T-shaped variable stars of Taurus are distributed in the upper right of the main sequence belt and located in the orbit of Hayashi, indicating that they are very young stars.

Taurus constellation

The late spectral star before the main sequence star belongs to the pre-main sequence star. According to the intensity of the emission line in the spectrum, it can be divided into two types: strong Taurus T-variable and weak Taurus T-variable. The former is more active than the latter. The typical T-variable star in Taurus emits a strong star wind, which is considered to be caused by the accretion of substances around the disk towards the center, and is the downward flowing residue during the formation of stars. In contrast, the weak Taurus T variable star lacks strong stellar wind and accretion disk, which may be the result of the diffusion of the surrounding astrolabe in the late evolution of the strong Taurus T variable star.

In principle, the diffuse nebula mixed with many young stars is the most suitable for observing Taurus T variables. But in fact, these star-forming regions are far away from the sun and 150 parsec (pc), so it is difficult to observe subtle changes in luminosity. The luminosity of T variable in Taurus shows some characteristic changes, many of which are periodic luminosity changes. These periodic luminosity changes are believed to be the result of the rotation of the star surface with spots, which can be cold (like sunspots) or hot (like spots in the sun's chromosphere). By comparing the sun with other active stars (such as RSCVn and BYDRa), we can estimate the latitude, size and shape of low temperature spots and how they change with time by analyzing the type, amplitude and period of photometric curves of T variable stars in Taurus. Taking the Taurus V4 10 star (V4 10Tau) as an example, based on the photometric observation data of five times in six years, it is deduced that its rotation period is 1.87 10 days, and the appearance and amplitude of its photometric change are in line with the changes of the size, temperature and distribution of the star spot expected by the model. The rotation period of the star before the main sequence star is an important parameter, which can only be inferred by photometric observation, so it is necessary to make long-term photometric observation of the T variable star in Taurus.

The rotation of T variable stars in Taurus is studied systematically, and the rotation speed of more than T variable stars in Taurus 100 is measured. Because Zhou Xiao's rotation speed is 20km per second, which reflects the mass of most T-variables in Taurus, Zhou Xiao is 1.25 solar masses. In the star before the main sequence star, the observation results show that the rotation speed increases with the increase of mass, which may be the result of the star formation process.