The star closest to Polaris ~ [with extra points]

In A.D., Polaris was the companion of Polaris. Because it is a dwarf star, the light is very dark and has been covered by the light of Polaris. Even ordinary astronomical telescopes can't observe it, and only Hubble's telescope will see through him.

The following is its information:

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Arctic 2 observation data

Era J2000

Ursa Minor

Guan xing

Right ascension14h50m 42.3 seconds

Declination+74 09' 20 "

Apparent magnitude (V) 2.07

characteristic

Spectral classification K4 III

B-V color index 1.47

U-B color index 1.77

Variable star type?

Astrometry

Radial velocity (RV)+16.8km/s

Self (μ) RA: -32.29 mass/year

1February: 1 1.9 1 MAS/ year

Parallax (π) 25.79 0.52 mas

Distance 126 3 Li

(38.8 0.8 percentage points)

Absolute magnitude (MV) -0.88

give exact information

Mass 4.4m ⊙ⅷ

Radius 4 1 R⊙ⅷ

Brightness 500 L⊙ VIII

Temperature 4000K

The amount of metal?

Rotation ~17km/s

Age? year

Other naming

Emperor, Ursa minor 7, Ursa minor β, Kocab, Kochah, Al Kaukab Al Shamaliyy, HR 5563, BD+74 595, HD 13 1873, GCTP 373.00, Sao 8 102, fk.

Arctic II (β UMi or β Ursa minor) is the second bright star of Little Beidou in Ursa minor, and its English name is Kochab. The brightness of North Pole II is 2. 1 etc. At present, the yellow giant is 0/6 degrees away from the North Pole and 0/0 light-years away from the Earth. Its true luminosity is 130 times that of the sun, and its surface temperature is about 4,000K K k.

Polaris II and the adjacent Polaris I (Ursa minor γ) are both visible stars, which together became the Polaris at that time during the period of 1 BC and 500-500 BC. Due to precession, the former Polaris rotates to the right, and then the present Gouchen-1 ... Polaris will constantly change due to precession of the earth's rotation axis.

The word Kochab is of unknown origin, maybe it comes from Arabic? The meaning of Al-kawkab is very simple, and it also means star in Hebrew.