Pollux, or Beta Gemini, means "boxer".The 17th bright star in the whole day (the brightest star at night is Canis MajorSirius）。The average apparent magnitude of Beihe Three is 1.14, and the absolute magnitude is 1.08, about 33.78 light-years away from the Earth.It is a K0III orange giant star, and the actual light is about 43 times that of the sun.It is one of the closest orange giants to the earth.[1]
Beihesan (meaning boxing master), also called“GeminiBeta star "is an orange giant star.Beihesan is located in Geminifixed starIt is also one of the 21 bright stars in the night sky.thanBeihe IIAnd bright.It is said that many centuries later,Beihe IIThe color has faded.Apparent magnitude: 1.14,Absolute magnitudeIt is 1.08, etc. According to spectral analysis, it is an orange giant star. Because it is a giant star, it is unstable and has a very long change period. Maybe this is why it is named β star. Of course, there is another reason because ancient Greek astronomers refer to the myth that it is set as β star because it is his brother.
It is an orange giant star. When viewed with binoculars, its color is quite eye-catching. It can be clearly seen in the north and middle of China, and you can search for nearbyOrionMove 5cm to the left in the sky to find two bright stars. The one below is Beihe San, which can clearly see its uniqueness. If you use binoculars or telescopes, you can clearly see that it is an orange giant star. According toCharge coupled elementIn photography, we can see some dim stars (like black dots orCloud gas）Scientists believe thatplanetOrBlack dwarf，hubble space telescope Similar clouds have also been found, and it is concluded that it is the object left by Beihesan when it engulfs the star, or it has nothing to do with it (just from the telescope).
Beihe III
Although he and Beihe'er are "brothers" in myth, in fact, Beihe'er is a star group composed of six stars (see entry:Beihe II）And it runs in the opposite direction to Beihesan, but its distance is different.Beihe 2 is 45 light years away from the earth, and Beihe 3 is 33.7 light years away from the earth[2]Beihesan is one of the brightest stars in the universeorangeAndBeihe IIOfblueIt is a sharp contrast and very beautiful.
Stellar property
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The apparent star magnitude of Beihesan is 1.14,[3]In the bright star catalogBeihe II(Alpha Gemini) is also bright.Compared with the sun, Beihesan has about twice the mass and 9 times the diameter of the sun[4]
Beihesan was originally an A-type main sequence star,[5]But the hydrogen fuel in the core has been exhausted and has evolved into a giant star with a spectrum type of K0III[6]The effective temperature of the outer shell of this star is about 4666 K,[7]The projection speed of Beihesan is 2.8 km • s within the range of K-type stars with orange hue.[8]
The abundances of elements other than hydrogen and helium, that is, the abundances of metals, are estimated to range from 85% to 155% of the sun, and there is no correct value (it should be noted that what astronomers say about metals refers to all other elements except hydrogen and helium).[8]
The Roentgen satellite (ROSAT) in orbit detected weak X-ray radiation, which is evidence of low-level magnetic activity in Beihesan.The X-ray radiation from this star is about 10twenty-sevenerg s−1, approximately equal to that from the sun.It has been confirmed that the surface magnetic field intensity of Beihesan is less than 1 Gauss, which is one of the weakest magnetic fields found on stars.The existence of magnetic field indicates that Beihesan was once an Ap star with stronger magnetic field.The radial velocity of a star has a small amplitude change, but it is not a photometric change.[9]
Planetary system
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Since 1993, scientists have measured the radial velocity oscillation, thus suspecting that there are three planets around Beihe[10]。It was confirmed and announced that it had a planet on June 16, 2006.It is calculated that the mass of Beihesan b is at least 2.3 times that of Jupiter, and the period around Beihesan is about 590 days.[11]
