c Ursae Majoris

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c Ursae Majoris
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Ursa Major
Right ascension 09h 14m 20.54261s[1]
Declination +61° 25′ 23.9407″[1]
Apparent magnitude (V) 5.20[2]
Spectral type G0 V[3]
U−B color index +0.08[2]
B−V color index +0.58[2]
Radial velocity (Rv) −14.3[4] km/s
Proper motion (μ) RA: −6.98[1] mas/yr
Dec.: −32.15[1] mas/yr
Parallax (π) 51.10 ± 0.32[1] mas
Distance 63.8 ± 0.4 ly
(19.6 ± 0.1 pc)
Absolute magnitude (MV) 3.75±0.06/8.2±0.6[3]
Period (P) 16.239631 ± 0.000015 d
Semi-major axis (a) 2.9±0.2 mas
Eccentricity (e) 0.10635±0.00054
Inclination (i) 106.0±12.0°
Longitude of the node (Ω) 107.0±14.0°
Periastron epoch (T) 2454358.214 ± 0.013 HJD
Argument of periastron (ω)
Semi-amplitude (K1)
35.344±0.018 km/s
Semi-amplitude (K2)
64.97±0.27 km/s
c UMa A
Mass 1.213[5] M
Radius 2.6±0.1[3] R
Surface gravity (log g) 3.98[6] cgs
Temperature 5,871[6] K
Metallicity [Fe/H] −0.13[6] dex
Rotational velocity (v sin i) 5.59[7] km/s
Age 5.41[5] Gyr
c UMa B
Mass 0.59−0.66[3] M
Radius 0.50±0.14[3] R
Luminosity 0.08±0.04[3] L
Other designations
c UMa, 16 UMa, BD+62° 1058, HD 79028, HIP 45333, HR 3648, SAO 14819.[8]
Database references

c Ursae Majoris is the Bayer designation for a double-lined spectroscopic binary star system in the northern constellation of Ursa Major. It has an apparent visual magnitude of 5.20,[2] which indicates that is visible to the naked eye. Parallax measurements yield an estimated distance of 63.8 light years from the Sun.[1]

The spectroscopic binary nature of this system was among the first 75 such discovered by the Dominion Astrophysical Observatory in 1919.[9] The pair orbit each other every 16.2 days with an eccentricity of 0.1. The semimajor axis of their orbit has an angle of around 2.9 mas, and the plane of the orbit is inclined to the line of sight at an angle of around 106°.[3]

The primary component has a stellar classification of G0 V, suggesting that it is a G-type main sequence star similar to ι Per. It has a mass of about 1.2 times the mass of the Sun, and 2.6 times the Sun's radius. The magnitude difference between the two components is estimated to be 4.5±0.6. The estimated properties of the secondary indicate that it is most likely a K-type main sequence star, the system displays no indication of chromospheric activity.[3]

The system has been examined for evidence of an infrared excess that could indicate the presence of a circumstellar debris disk, but none has been found,[10] at present, c UMa is moving in Earth's direction with a radial velocity of −14.3 km/s. Perihelion passage will occur in 1.3 million years when the system comes within 10 ly (4 pc) of the Sun.[4] This is most likely a member of the Milky Way's thin disk population of stars.[5]


  1. ^ a b c d e f van Leeuwen, F. (2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics, 474 (2): 653–664, arXiv:0708.1752Freely accessible, Bibcode:2007A&A...474..653V, doi:10.1051/0004-6361:20078357. 
  2. ^ a b c d Mermilliod, J.-C. (1986), "Compilation of Eggen's UBV data, transformed to UBV (unpublished)", SIMBAD Astronomical Database, Bibcode:1986EgUBV........0M. 
  3. ^ a b c d e f g h i Francis C., Fekel; et al. (February 2015), "New Precision Orbits of Bright Double-Lined Spectroscopic Binaries. IX. HD 54371, HR 2692, and 16 Ursa Majoris", The Astronomical Journal, 149 (2): 13, Bibcode:2015AJ....149...63F, doi:10.1088/0004-6256/149/2/63, 63. 
  4. ^ a b Bailer-Jones, C. A. L. (March 2015), "Close encounters of the stellar kind", Astronomy & Astrophysics, 575: 13, arXiv:1412.3648Freely accessible, Bibcode:2015A&A...575A..35B, doi:10.1051/0004-6361/201425221, A35. 
  5. ^ a b c Ramírez, I.; et al. (February 2013), "Oxygen abundances in nearby FGK stars and the galactic chemical evolution of the local disk and halo", The Astrophysical Journal, 764 (1): 78, arXiv:1301.1582Freely accessible, Bibcode:2013ApJ...764...78R, doi:10.1088/0004-637X/764/1/78. 
  6. ^ a b c Gray, R. O.; et al. (July 2006), "Contributions to the Nearby Stars (NStars) Project: spectroscopy of stars earlier than M0 within 40 pc-The Southern Sample", The Astronomical Journal, 132 (1): 161–170, arXiv:astro-ph/0603770Freely accessible, Bibcode:2006AJ....132..161G, doi:10.1086/504637. 
  7. ^ Martínez-Arnáiz, R.; et al. (September 2010), "Chromospheric activity and rotation of FGK stars in the solar vicinity. An estimation of the radial velocity jitter", Astronomy and Astrophysics, 520: A79, arXiv:1002.4391Freely accessible, Bibcode:2010A&A...520A..79M, doi:10.1051/0004-6361/200913725. 
  8. ^ "c UMa". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2016-07-18. 
  9. ^ Plaskett, J. S.; et al. (1919). "Fourth list of spectroscopic binaries". Journal of the Royal Astronomical Society of Canada. 13: 372–378. Bibcode:1919JRASC..13..372P. 
  10. ^ Eiroa, C.; et al. (July 2013), "DUst around NEarby Stars. The survey observational results", Astronomy & Astrophysics, 555: A11, arXiv:1305.0155Freely accessible, Bibcode:2013A&A...555A..11E, doi:10.1051/0004-6361/201321050.