Alpha Monocerotis

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Alpha Monocerotis
Diagram showing star positions and boundaries of the Monoceros constellation and its surroundings
Cercle rouge 100%.svg

Location of α Monocerotis (circled)
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Monoceros
Right ascension 07h 41m 14.8324s
Declination –09° 33′ 04.071″
Apparent magnitude (V) 3.94[1]
Spectral type K0 III[1]
B−V color index 1.022[1]
Radial velocity (Rv) +10.50[1] km/s
Distance 144 ly
(44.2 pc)
Absolute magnitude (MV) 0.71 ± 0.08[2]
Mass 2.02 ± 0.29[2] M
Radius 10.1 ± 0.5[2] R
Surface gravity (log g) 2.71 ± 0.09[2] cgs
Temperature 4,879[2] K
Metallicity [Fe/H] −0.01[2] dex
Rotation 326 days[3]
Rotational velocity (v sin i) 1.9[3] km/s
Age 1.18 ± 0.42[2] Gyr
Other designations
26 Monocerotis, BD–09 2172, HD 61935, HIP 37447, HR 2970, IRAS 07388-0926, SAO 134986.

Alpha Monocerotis (α Mon, α Monocerotis) is the Bayer designation for the brightest star in the equatorial constellation of Monoceros.

It is a giant star with a stellar classification of K0 III[1] and is of apparent magnitude 3.93. It is approximately 144 light years from Earth.


  1. ^ a b c d e Hekker, S.; et al. (August 2006), "Precise radial velocities of giant stars. I. Stable stars", Astronomy and Astrophysics 454 (3): 943–949, arXiv:astro-ph/0604502, Bibcode:2006A&A...454..943H, doi:10.1051/0004-6361:20064946. 
  2. ^ a b c d e f g da Silva, L.; et al. (November 2006), "Basic physical parameters of a selected sample of evolved stars", Astronomy and Astrophysics 458 (2): 609–623, arXiv:astro-ph/0608160, Bibcode:2006A&A...458..609D, doi:10.1051/0004-6361:20065105. 
  3. ^ a b Setiawan, J.; et al. (July 2004), "Precise radial velocity measurements of G and K giants. Multiple systems and variability trend along the Red Giant Branch", Astronomy and Astrophysics 421: 241–254, Bibcode:2004A&A...421..241S, doi:10.1051/0004-6361:20041042-1. 

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