| Observation data Epoch J2000 Equinox J2000 |
|
|---|---|
| Constellation | Ursa Minor |
| Right ascension | 14h 50m 42.3s |
| Declination | +74° 09′ 20″ |
| Apparent magnitude (V) | 2.07[1] |
| Characteristics | |
| Spectral type | K4 III[1] |
| U−B color index | 1.77 |
| B−V color index | 1.47[1] |
| Variable type | ? |
| Astrometry | |
| Radial velocity (Rv) | +16.8 km/s |
| Proper motion (μ) | RA: -32.29 mas/yr Dec.: 11.91 mas/yr |
| Parallax (π) | 25.79 ± 0.52 mas |
| Distance | 126 ± 3 ly (38.8 ± 0.8 pc) |
| Absolute magnitude (MV) | -0.88 |
| Details | |
| Mass | 4.4[1] M☉ |
| Radius | 41 R☉ |
| Luminosity | 500 L☉ |
| Temperature | 4,000 K |
| Metallicity | ? |
| Rotation | ~17 km/s. |
| Age | ? years |
| Other designations | |
Beta Ursae Minoris (β UMi, β Ursae Minoris) is the brightest star in the bowl of the "Little Dipper" (which is part of the constellation Ursa Minor), and only slightly fainter than Polaris, the northern pole star and brightest star in Ursa Minor. It has the traditional name Kochab. Kochab's magnitude is 2.07.[1] It is 16 degrees from Polaris. The star is an orange giant and is 126.4 ± 2.5 light years from Earth.[1] It is 130 times more luminous than the Sun. Kochab has a surface temperature of approximately 4,000 K.
Kochab and its neighbor Pherkad are both naked eye stars and are sometimes referred to as the "Guardians of the Pole". They served as twin pole stars, Earth's North pole stars, from 1500 BC until 500 AD. Neither star was as proximitous to the pole as Polaris is now. Due to precession of the equinoxes, the previous holder of the title was Thuban, and the next was the present-day Polaris. This succession of pole stars is a result of earth's precessional motion.
The origin of the name Kochab is unclear. It comes from the Hebrew word for star, "kokhav"[2], כוכב. It appears to be cognate with Arabic الكوكب al-kawkab "the star", short for الكوكب الشمالي al-kawkab al-šamāliyy "the north star" (lit. heavenly body), named when it was still the pole star.
In Chinese, 北極 (Běi Jí), meaning North Pole, refers to an asterism consisting of β Ursae Minoris, γ Ursae Minoris, 5 Ursae Minoris, 4 Ursae Minoris and Σ 1694.[3] Consequently, β Ursae Minoris itself is known as 北極二 (Běi Jí èr, English: the Second Star of North Pole.),[4] representing 帝 (Dì), meaning Emperor.[5]
Mythology: Bx Times Reporter, New York http://www.webspawner.com/users/cosmic/
| Preceded by Thuban |
Pole Star 1900 BC–500 |
Succeeded by Polaris |
Coordinates: 14h 50m 42.3s, +74° 09′ 20″
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