Beta Ursae Minoris

Kochab
Location of β Ursae Minoris (circled)
Observation data
Epoch J2000      Equinox J2000
Constellation Ursa Minor
Right ascension 14h 50m 42.32580s[1]
Declination +74° 09′ 19.8142″[1]
Apparent magnitude (V) 2.08[2]
Characteristics
Spectral type K4 III[3]
U−B color index +1.78[2]
B−V color index +1.47[2]
Astrometry
Radial velocity (Rv)+16.96[4] km/s
Proper motion (μ) RA: −32.61[1] mas/yr
Dec.: +11.42[1] mas/yr
Parallax (π)24.91 ± 0.12 mas[1]
Distance130.9 ± 0.6 ly
(40.1 ± 0.2 pc)
Absolute magnitude (MV)−0.83±0.010[5]
Details[6]
Mass1.3±0.3[7] M☉
Radius44.13±0.22[8] R☉
Luminosity454±37[8] L☉
Surface gravity (log g)1.39±0.06 cgs
Temperature4,008±37[8] K
Metallicity [Fe/H]−0.27±0.07 dex
Rotation625 – 6457 days
Rotational velocity (v sin i)1.7±1.4 km/s
Age2.95±1.03 Gyr
Other designations
Kocab, Kochah, 7 Ursae Minoris, Al Kaukab al Shamaliyy, BD+74 595, FK5 550, HD 131873, HIP 72607, HR 5563, SAO 8102, PLX 3373.00[9]
Database references
SIMBADBeta Ursae Minoris

Kochab /ˈkoʊkæb/, Bayer designation Beta Ursae Minoris (β Ursae Minoris, abbreviated β UMi, Beta UMi),[10][11] is the brightest star in the bowl of the Little Dipper asterism (which is part of the constellation of Ursa Minor), and only slightly fainter than Polaris, the northern pole star and brightest star in Ursa Minor. Kochab is 16 degrees from Polaris and has an apparent visual magnitude of 2.08.[2] The distance to this star from the Sun can be deduced from the parallax measurements made during the Hipparcos mission, yielding a value of 130.9 light-years (40.1 parsecs).[1]

Amateur astronomers can use Kochab as a precise guide for equatorial mount alignment: The celestial north pole is located 38 arcminutes away from Polaris, very close to the line connecting Polaris with Kochab.[12]

  1. ^ a b c d e f Cite error: The named reference Leeuwen was invoked but never defined (see the help page).
  2. ^ a b c d Cite error: The named reference Johnson was invoked but never defined (see the help page).
  3. ^ Cite error: The named reference Morgan1973 was invoked but never defined (see the help page).
  4. ^ Cite error: The named reference Famaey was invoked but never defined (see the help page).
  5. ^ Cite error: The named reference Park2013 was invoked but never defined (see the help page).
  6. ^ Cite error: The named reference Lee-etal-2014 was invoked but never defined (see the help page).
  7. ^ Cite error: The named reference Tarrant was invoked but never defined (see the help page).
  8. ^ a b c Cite error: The named reference Baines2021 was invoked but never defined (see the help page).
  9. ^ Cite error: The named reference SIMBAD was invoked but never defined (see the help page).
  10. ^ Cite error: The named reference Kunitzsch-Smart-2006 was invoked but never defined (see the help page).
  11. ^ Cite error: The named reference IAU-CSN was invoked but never defined (see the help page).
  12. ^ "Geocentric Positions of Major Solar System Objects and Bright Stars". US Naval Observatory. Retrieved August 6, 2022.