Iota Canis Majoris

ι Canis Majoris
Location of ι Canis Majoris (circled)
Observation data
Epoch J2000      Equinox J2000
Constellation Canis Major
Right ascension 06h 56m 08.2246s[1]
Declination −17° 03′ 15.259″[1]
Apparent magnitude (V) 4.40[2] (4.36 to 4.40)[3]
Characteristics
Evolutionary stage Supergiant
Spectral type B3 Ib[4] or B3 Ib/II[5]
U−B color index −0.74[6]
B−V color index −0.07[6]
Astrometry
Radial velocity (Rv)41.75±0.43[1] km/s
Proper motion (μ) RA: −3.547 mas/yr[1]
Dec.: 3.190 mas/yr[1]
Parallax (π)0.9453±0.1857 mas[1]
Distance3,100±130 ly
(950±40 pc)[7]
Absolute magnitude (MV)−5.51[8]
Details[7]
Mass13.7±0.5 M☉
Radius32±4 R☉
Luminosity52,480 L☉
Surface gravity (log g)2.59±0.05 cgs
Temperature15,600±400 K
Metallicity [Fe/H]−0.17[9] dex
Rotational velocity (v sin i)30±6 km/s
Age14.79+1.43
−1.30 Myr
Other designations
ι CMa, 20 Canis Majoris, BD−16°1661, FK5 2536, GC 9107, HD 51309, HIP 33347, HR 2596, SAO 152126[10]
Database references
SIMBADdata

Iota Canis Majoris is a solitary[11] supergiant star in the southern constellation of Canis Major. Its name is a Bayer designation that is Latinized from ι Canis Majoris, and abbreviated Iota CMa or ι CMa. This is a variable star that ranges in apparent visual magnitude from +4.36 to +4.40, which is faintly visible to the naked eye.[3] The distance to this star is approximately 3,100 light years based on spectroscopic measurements.[7] It is drifting further away from the Sun with a radial velocity of +42 km/s.[1]

A light curve for Iota Canis Majoris, plotted from TESS data.[12]

Iota Canis Majoris is a massive blue-white B-type supergiant with a stellar classification of B3 Ib.[4] It has been classified as a Beta Cephei type variable star,[3] but the supergiant spectral type and a period of over a day mean it is no longer considered to be of that type.[2] This star is 15 million years old and is spinning with a projected rotational velocity of 30 km/s. It has 14 times the mass and 32 times the radius of the Sun. Iota Canis Majoris is radiating 52,000 times the luminosity of the Sun from its photosphere at an effective temperature of 15,600 K.[7]

The star displays a bow shock feature from its interaction with the interstellar medium, but this nebulosity is not aligned with the star's motion through the galaxy.[13]

References

  1. ^ a b c d e f Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy and Astrophysics. 674: A1. arXiv:2208.00211. Bibcode:2023A&A...674A...1G. doi:10.1051/0004-6361/202243940. S2CID 244398875. Gaia DR3 record for this source at VizieR.
  2. ^ a b Stankov, Anamarija; Handler, Gerald (2005). "Catalog of Galactic β Cephei Stars". The Astrophysical Journal Supplement Series. 158 (2): 193–216. arXiv:astro-ph/0506495. Bibcode:2005ApJS..158..193S. doi:10.1086/429408. ISSN 0067-0049. S2CID 119526948.
  3. ^ a b c Samus, N. N.; Durlevich, O. V.; et al. (2009). "VizieR Online Data Catalog: General Catalogue of Variable Stars (Samus+ 2007-2013)". VizieR On-line Data Catalog: B/GCVS. Originally Published in: 2009yCat....102025S. 1: 02025. Bibcode:2009yCat....102025S.
  4. ^ a b Prinja, R. K.; Massa, D. L. (2010). "Signature of wide-spread clumping in B supergiant winds". Astronomy and Astrophysics. 521: L55. arXiv:1007.2744. Bibcode:2010A&A...521L..55P. doi:10.1051/0004-6361/201015252. ISSN 0004-6361. S2CID 59151633.
  5. ^ Houk, Nancy; Smith-Moore, M. (1978). Michigan catalogue of two-dimensional spectral types for the HD stars. Vol. 4. Ann Arbor: Dept. of Astronomy, University of Michigan. Bibcode:1988mcts.book.....H.
  6. ^ a b Mermilliod, J.-C. (1986). "Compilation of Eggen's UBV data, transformed to UBV (unpublished)". Catalogue of Eggen's UBV Data. Bibcode:1986EgUBV........0M.
  7. ^ a b c d Weßmayer, D.; et al. (December 2022). "Quantitative spectroscopy of B-type supergiants". Astronomy & Astrophysics. 668: A92. arXiv:2208.02692. Bibcode:2022A&A...668A..92W. doi:10.1051/0004-6361/202243973. ISSN 0004-6361.
  8. ^ Balona, L. A.; Engelbrecht, C. A. (1985). "Photometry and frequency analysis of line profile variables". Monthly Notices of the Royal Astronomical Society. 214 (4): 559. Bibcode:1985MNRAS.214..559B. doi:10.1093/mnras/214.4.559.
  9. ^ Gies, Douglas R.; Lambert, David L. (1992). "Carbon, nitrogen, and oxygen abundances in early B-type stars". Astrophysical Journal. 387: 673. Bibcode:1992ApJ...387..673G. doi:10.1086/171116.
  10. ^ "iot CMa". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2025-07-13.
  11. ^ 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. S2CID 14878976.
  12. ^ "MAST: Barbara A. Mikulski Archive for Space Telescopes". Space Telescope Science Institute. Archived from the original on 27 March 2023. Retrieved 29 September 2024.
  13. ^ Bodensteiner, J.; et al. (October 2018). "Infrared nebulae around bright massive stars as indicators for binary interactions". Astronomy & Astrophysics. 618: 13. arXiv:1806.01294. Bibcode:2018A&A...618A.110B. doi:10.1051/0004-6361/201832722. S2CID 118972162. A110.
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