Nu3 Canis Majoris

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Nu3 Canis Majoris
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Canis Major
Right ascension  06h 37m 53.42144s[1]
Declination −18° 14′ 14.9218″[1]
Apparent magnitude (V) 4.41[2] (4.63 + 8.56)[3]
Spectral type K0 II-III[4]
U−B color index +1.04[2]
B−V color index +1.16[2]
Radial velocity (Rv)−1.50±0.70[5] km/s
Proper motion (μ) RA: −7.32[1] mas/yr
Dec.: −8.72[1] mas/yr
Parallax (π)7.74 ± 0.43[1] mas
Distance420 ± 20 ly
(129 ± 7 pc)
Absolute magnitude (MV)−1.13[6]
ν3 CMa A
Mass3.38±0.37[7] M
Radius32.7 R
Luminosity398 L
Surface gravity (log g)2.34 cgs
Temperature4,510 K
Metallicity [Fe/H]−0.24 dex
Rotation183 d
Rotational velocity (v sin i)8[8] km/s
Age380±20[7] Myr
Other designations
ν3 CMa, 8 Canis Majoris, BD−18°1492, GC 8660, HD 47442, HIP 31700, HR 2443, SAO 151730, CCDM 06379-1814[9]
Database references

Nu3 Canis Majoris, Latinized from ν3 Canis Majoris, is a binary star[3] system in the southern constellation of Canis Major.


The star system, appearing as one star, is deemed visible to the naked eye with its combined apparent visual magnitude of 4.41.[2] Based upon an annual parallax shift of 7.74 mas as seen from Earth,[1] this system is about 420 light years from the Sun, much further than Nu1 and Nu2 which appear nearby when seen from one point in our solar system.

The primary member, component A, is an evolved, orange-hued giant/bright giant hybrid with an apparent magnitude of +4.63[3] and a stellar classification of K0 II-III.[4] It is most likely (96% chance) on the horizontal branch;[7] the star has a moderate level of surface activity with a magnetic field strength of 2.2±0.4 G and is a source of X-ray emission with a luminosity of 624×1027 erg s−1.[4]

This giant has an estimated 3.4[7] times the mass of the Sun and has expanded to 33[4] times the Sun's radius. It is radiating 398 times the Sun's luminosity from its enlarged photosphere at an effective temperature of 4,510 K;[4] the star is spinning with the leisurely period of 183 days.[4] Its companion, component B has been observed at 1.040 arcseconds distant and has an apparent magnitude of +8.56.[3]


  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:0708.1752, Bibcode:2007A&A...474..653V, doi:10.1051/0004-6361:20078357.
  2. ^ a b c d Fernie, J. D. (May 1983), "New UBVRI photometry for 900 supergiants", Astrophysical Journal Supplement Series, 52: 7–22, Bibcode:1983ApJS...52....7F, doi:10.1086/190856.
  3. ^ a b c d Eggleton, P. P.; Tokovinin, A. A. (September 2008), "A catalogue of multiplicity among bright stellar systems", Monthly Notices of the Royal Astronomical Society, 389 (2): 869–879, arXiv:0806.2878, Bibcode:2008MNRAS.389..869E, doi:10.1111/j.1365-2966.2008.13596.x.
  4. ^ a b c d e f g Aurière, M.; et al. (2015), "The magnetic fields at the surface of active single G-K giants", Astronomy & Astrophysics, 574, arXiv:1411.6230, Bibcode:2015A&A...574A..90A, doi:10.1051/0004-6361/201424579, A90.
  5. ^ de Bruijne, J. H. J.; Eilers, A.-C. (October 2012), "Radial velocities for the HIPPARCOS-Gaia Hundred-Thousand-Proper-Motion project", Astronomy & Astrophysics, 546: 14, arXiv:1208.3048, Bibcode:2012A&A...546A..61D, doi:10.1051/0004-6361/201219219, A61.
  6. ^ Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", Astronomy Letters, 38 (5): 331, arXiv:1108.4971, Bibcode:2012AstL...38..331A, doi:10.1134/S1063773712050015.
  7. ^ a b c d Reffert, Sabine; et al. (2015), "Precise radial velocities of giant stars. VII. Occurrence rate of giant extrasolar planets as a function of mass and metallicity", Astronomy & Astrophysics, 574: A116, arXiv:1412.4634, Bibcode:2015A&A...574A.116R, doi:10.1051/0004-6361/201322360, hdl:10722/215277.
  8. ^ Bernacca, P. L.; Perinotto, M. (1970), "A catalogue of stellar rotational velocities", Contributi Osservatorio Astronomico di Padova in Asiago, 239 (1), Bibcode:1970CoAsi.239....1B.
  9. ^ "nu03 CMa". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2017-09-05.