Zeta Canis Majoris

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Zeta Canis Majoris
Diagram showing star positions and boundaries of the Canis Major constellation and its surroundings
Cercle rouge 100%.svg

Location of ζ Canis Majoris (circled)
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Canis Major
Right ascension 06h 20m 18.79204s[1]
Declination –30° 03′ 48.1202″[1]
Apparent magnitude (V) +3.025[2]
Spectral type B2.5 V[3]
U−B color index –0.71[2]
B−V color index –0.195[2]
Variable type Suspected β Cep[4]
Radial velocity (Rv) +32.2[5] km/s
Proper motion (μ) RA: +7.32[1] mas/yr
Dec.: +4.03[1] mas/yr
Parallax (π) 9.00 ± 0.13[1] mas
Distance 362 ± 5 ly
(111 ± 2 pc)
Period (P) 675 days
Eccentricity (e) 0.57
Mass 7.7 ± 0.2[7] M
Radius 3.9[8] R
Luminosity 3,603[9] L
Surface gravity (log g) 4.0[8] cgs
Temperature 18,700[9] K
Rotational velocity (v sin i) 25[10] km/s
Age 32.0 ± 0.4[7] Myr
Other designations
Furud, Phurud, ζ CMa, 1 CMa, CD −30° 3038, FK5 240, HD 44402, HIP 30122, HR 2282, SAO 196698.[11]

Zeta Canis Majoris (ζ CMa, ζ Canis Majoris) is a spectroscopic binary in the constellation Canis Major. It has the traditional name Furud or Phurud, from the Arabic ألفرد al-furud meaning the bright single ones or, perhaps by a transcriber's error, from Al Ḳurūd (ألقرد - al-qird), the Apes, or Al Agribah (أل أغربة), the Raven by Al Sufi, referring to the surrounding small stars with some of those of Columba[12] (ζ CMa, λ CMa, γ Col, δ Col, θ Col, κ Col, λ Col, μ Col and ξ Col).[13] The Bayer designation Zeta Canis Majoris was assigned by German astronomer Johann Bayer in 1603.

This star system has an apparent visual magnitude of +3.0,[2] making it one of the brighter stars in the constellation and hence readily visible to the naked eye. Parallax measurements from the Hipparcos mission yield a distance estimate of around 362 ly (111 pc) from Earth.[1] This is a single-lined spectroscopic binary system, which means that the pair have not been individually resolved with a telescope, but the gravitational perturbations of an unseen astrometric companion can be discerned by shifts in the spectrum of the primary caused by the Doppler effect. The pair orbit around their common center of mass once every 675 days with an eccentricity of 0.57.[6]

The primary component is a large star with nearly four[8] times the Sun's radius and almost eight[7] times the mass of the Sun. It has a stellar classification of B2.5 V,[3] which means it is a B-type main sequence star that is generating energy through the nuclear fusion of hydrogen at its core. It is emitting 3,603[9] times the luminosity of the Sun and is a suspected Beta Cephei variable.[4] This energy is being radiated from its outer envelope at an effective temperature of about 18,700 K,[9] giving it the blue-white hue of a B-type star.[14] It is relatively young for a star, with an estimated age of 32 million years.[7]


  1. ^ a b c d e f van Leeuwen, F. (November 2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics 474 (2): 653–664, arXiv:0708.1752, Bibcode:2007A&A...474..653V, doi:10.1051/0004-6361:20078357 
  2. ^ a b c d Cousins, A. W. J. (1972), "UBV Photometry of Some Very Bright Stars", Monthly Notes of the Astronomical Society, Southern Africa 31: 69, Bibcode:1972MNSSA..31...69C 
  3. ^ a b Houk, Nancy (1979), Michigan catalogue of two-dimensional spectral types for the HD stars 3, Ann Arbor, Michigan: Dept. of Astronomy, University of Michigan, Bibcode:1982MSS...C03....0H 
  4. ^ a b Telting, J. H. et al. (June 2006), "A high-resolution spectroscopy survey of β Cephei pulsations in bright stars", Astronomy and Astrophysics 452 (3): 945–953, Bibcode:2006A&A...452..945T, doi:10.1051/0004-6361:20054730 
  5. ^ Evans, D. S. (June 20–24, 1966), "The Revision of the General Catalogue of Radial Velocities", in Batten, Alan Henry; John Frederick, Determination of Radial Velocities and their Applications, Proceedings from IAU Symposium no. 30, University of Toronto: International Astronomical Union, Bibcode:1967IAUS...30...57E 
  6. ^ a b Abt, Helmut A. (August 2005), "Observed Orbital Eccentricities", The Astrophysical Journal 629 (1): 507–511, Bibcode:2005ApJ...629..507A, doi:10.1086/431207 
  7. ^ a b c d Tetzlaff, N.; Neuhäuser, R.; Hohle, M. M. (January 2011), "A catalogue of young runaway Hipparcos stars within 3 kpc from the Sun", Monthly Notices of the Royal Astronomical Society 410 (1): 190–200, arXiv:1007.4883, Bibcode:2011MNRAS.410..190T, doi:10.1111/j.1365-2966.2010.17434.x 
  8. ^ a b c Underhill, A. B. et al. (November 1979), "Effective temperatures, angular diameters, distances and linear radii for 160 O and B stars", Monthly Notices of the Royal Astronomical Society 189: 601–605, Bibcode:1979MNRAS.189..601U 
  9. ^ a b c d Hohle, M. M.; Neuhäuser, R.; Schutz, B. F. (April 2010), "Masses and luminosities of O- and B-type stars and red supergiants", Astronomische Nachrichten 331 (4): 349, arXiv:1003.2335, Bibcode:2010AN....331..349H, doi:10.1002/asna.200911355 
  10. ^ Abt, Helmut A.; Levato, Hugo; Grosso, Monica (July 2002), "Rotational Velocities of B Stars", The Astrophysical Journal 573 (1): 359–365, Bibcode:2002ApJ...573..359A, doi:10.1086/340590 
  11. ^ "zet CMa -- Cepheid variable Star", SIMBAD Astronomical Object Database (Centre de Données astronomiques de Strasbourg), retrieved 2012-02-15 
  12. ^ Allen, R. H. (1963), Star Names: Their Lore and Meaning (Reprint ed.), New York: Dover Publications Inc, p. 130, ISBN 0-486-21079-0, retrieved 2010-12-12 
  13. ^ Davis Jr., G. A. (October 1944), "The Pronunciations, Derivations, and Meanings of a Selected List of Star Names", Popular Astronomy 52 (3): 14, Bibcode:1944PA.....52....8D 
  14. ^ "The Colour of Stars", Australia Telescope, Outreach and Education (Commonwealth Scientific and Industrial Research Organisation), December 21, 2004, retrieved 2012-01-16 

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