Astronomy:Omicron1 Canis Majoris

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Short description: Variable star in the constellation Canis Major


For other stars with this Bayer designation, see ο Canis Majoris.
ο1 Canis Majoris
Location of ο1 CMa (circled)
Observation data
Equinox J2000.0]] (ICRS)
Constellation Canis Major
Right ascension  06h 54m 07.9523s[1]
Declination −24° 11′ 03.160″[1]
Apparent magnitude (V) 3.87[2] (3.78 to 3.99[3])
Characteristics
Evolutionary stage Red supergiant
Spectral type K2.5 Iab[4]
U−B color index +1.99[2]
B−V color index +1.73[2]
Variable type Slow irregular variable (Lc)[3]
Astrometry
Radial velocity (Rv)+36.3[5] km/s
Proper motion (μ) RA: −3.771[1] mas/yr
Dec.: 4.503[1] mas/yr
Parallax (π)1.2869 ± 0.1209[1] mas
Distance2,673±241 ly
(820±74 pc)
Absolute magnitude (MV)−4.69[4]
Details
Mass7.83±2.0 M☉[6]
14.38±2.88 M☉[7]
18[8] M☉
Radius390[9] R☉
Luminosity37,414[9] L☉
Temperature4,015[9] K
Metallicity [Fe/H]−0.11[10] dex
Rotational velocity (v sin i)12.31[11] km/s
Age18[8] Myr
Other designations
16 Canis Majoris, CD−24°4567, GC 9059, HD 50877, HIP 33152, HR 2580, SAO 172542[12]
Database references
SIMBADdata

Omicron1 Canis Majoris is a red supergiant star in the constellation Canis Major. Its name is a Bayer designation that is Latinized from ο1 Canis Majoris, and abbreviated Omicron1 CMa or ο1 CMa. This is a variable star that ranges in apparent visual magnitude from 3.78 to 3.99,[3] which is bright enough to be viewed with the naked eye. It is located at a distance of approximately 2,700 light years,[13] and is drifting further away with a line of sight velocity of +36 km/s.[5]

Name

Johann Bayer gave two adjacent stars the Bayer designation of ο Canis Majoris in 1603, but without distinguishing between the stars. John Flamsteed gave the two omicron stars his own numbered designations of 16 and 24 Canis Majoris in the early 18th century.[14] Friedrich Wilhelm Argelander labelled the stars as ο1 and ο2 in his atlas Uranometria Nova.[15] Nicolas Louis de Lacaille labelled it c Canis Majoris, but this was not upheld by subsequent cartographers.[16] Its Henry Draper Catalogue designation is HD 50877. The two Omicron stars marked the centre of the Great Dog's body on Bayer's 1603 Uranometria.[17]

Distance

Omicron1 Canis Majoris is the brightest star in this image; EZ Canis Majoris is below it (south is up)

The distance to ο1 Canis Majoris is uncertain. It is strongly associated with the Collinder 121 stellar association, located around 3,500 light years (1,085 parsecs) distant.[18] Its original Hipparcos parallax placed it at 610 pc, similar to the distance of EZ Canis Majoris, another member of Cr 121. ο1 CMa appears to be interacting with the nebula around EZ CMa, implying the two are at the same distance.[19] However, the revised Hipparcos parallax is only 0.22 mas, with a large margin of error of 0.43 mas,[20] so the distance is not well-defined but likely to be large. The distance to EZ CMa is now thought to be around 1,500 pc.[21] Conversely, though only separated by 2 degrees from the blue supergiant ο2 Canis Majoris, the two appear to be unrelated.[8]

Bailer-Jones et al. (2021) estimate a distance of 820 parsecs, give or take 74 parsecs to Omicron1 Canis Majoris, using a method that use its parallax from Gaia EDR3, its color and apparent magnitude.[13]

Description

A light curve for Omicron1 Canis Majoris, plotted from Hipparcos data[22]

The star itself is an orange K-type supergiant of spectral type K2.5 Iab and is an irregular variable star, varying between apparent magnitudes 3.78 and 3.99. A cool star, its surface temperature is around 4,000 K.[9] Around 8 times as massive as the Sun[6] with around 390 times its diameter, it shines with 37,000 times its luminosity.[9] Interstellar dust only obscures it slightly, and its apparent magnitude is 0.16 fainter than it would be if unobscured.[4] Thought to be around 18 million years old, ο1 Canis Majoris is undergoing nuclear fusion of helium in its core to generate energy and will one day explode as a type II supernova.[8]

References

  1. ↑ 1.0 1.1 1.2 1.3 Vallenari, A. et al. (2022). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy & Astrophysics. doi:10.1051/0004-6361/202243940  Gaia DR3 record for this source at VizieR.
  2. ↑ 2.0 2.1 2.2 Ducati, J. R. (2002). "VizieR Online Data Catalog: Catalogue of Stellar Photometry in Johnson's 11-color system". CDS/ADC Collection of Electronic Catalogues 2237. Bibcode: 2002yCat.2237....0D. 
  3. ↑ 3.0 3.1 3.2 Samus, N. N. 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. Bibcode: 2009yCat....102025S. 
  4. ↑ 4.0 4.1 4.2 Levesque, E. M. et al. (2005). "The Effective Temperature Scale of Galactic Red Supergiants: Cool, but Not as Cool as We Thought". The Astrophysical Journal 628 (2): 973–985. doi:10.1086/430901. Bibcode: 2005ApJ...628..973L. 
  5. ↑ 5.0 5.1 Evans, D. S. (1967). "The Revision of the General Catalogue of Radial Velocities". Determination of Radial Velocities and Their Applications 30: 57. Bibcode: 1967IAUS...30...57E. 
  6. ↑ 6.0 6.1 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. doi:10.1051/0004-6361/201322360. Bibcode: 2015A&A...574A.116R. 
  7. ↑ Kervella, Pierre et al. (January 2022). "Stellar and substellar companions from Gaia EDR3. Proper-motion anomaly and resolved common proper-motion pairs". Astronomy and Astrophysics 657: A7. doi:10.1051/0004-6361/202142146. ISSN 0004-6361. Bibcode: 2022A&A...657A...7K.  o1 Canis Majoris' database entry at VizieR.
  8. ↑ 8.0 8.1 8.2 8.3 Kaler, James B.. "Omicron1 Canis Majoris". Stars. University of Illinois. http://stars.astro.illinois.edu/sow/omi1cma.html. 
  9. ↑ 9.0 9.1 9.2 9.3 9.4 Healy, Sarah et al. (March 23, 2024). "Red Supergiant Candidates for Multimessenger Monitoring of the Next Galactic Supernova". Monthly Notices of the Royal Astronomical Society 529 (4): 3630–3650. doi:10.1093/mnras/stae738. ISSN 0035-8711. Bibcode: 2024MNRAS.529.3630H. 
  10. ↑ Marrese, P. M. et al. (2003). "High resolution spectroscopy over lambda lambda 8500-8750 Å for GAIA. IV. Extending the cool MK stars sample". Astronomy and Astrophysics 406 (3): 995. doi:10.1051/0004-6361:20030647. Bibcode: 2003A&A...406..995M. 
  11. ↑ Hekker, S.; Meléndez, J. (2007). "Precise radial velocities of giant stars". Astronomy and Astrophysics 475 (3): 1003. doi:10.1051/0004-6361:20078233. Bibcode: 2007A&A...475.1003H. 
  12. ↑ "omi01 CMa". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=omi01+CMa. 
  13. ↑ 13.0 13.1 Bailer-Jones, C. A. L. et al. (2021). "Estimating Distances from Parallaxes. V. Geometric and Photogeometric Distances to 1.47 Billion Stars in Gaia Early Data Release 3". The Astronomical Journal 161 (3): 147. doi:10.3847/1538-3881/abd806. Bibcode: 2021AJ....161..147B.  Data about this star can be seen here.
  14. ↑ Flamsteed, John et al. (1725). Historia Coelestis Britannica: Complectens Praefationem spatiosam (sive in Stellarum Fixarum Catalogum Prolegomena) quae brevem Astronomiae Historiam praebet, atque Descriptionem Observationum peractarum, & Organorum adhibitorum tum a pristinis Astronomis, tum In Observatorio Regio Grenovicensi; Deinceps Fixarum Catalogum a Ptolemaeo, Uleg Beig, Tychone Brahaeo, Gulielmo Hessiae Landtgravio, ac Hevelio constructum ...: Quibus adnexus est Fixarum quarundam Australium Catalogus, in nostro Hemisphaerio non adspectabilium, Denique Tabulae …. Meere. pp. 2–. https://archive.org/details/bub_gb_8q9FAAAAcAAJ. 
  15. ↑ Argelander, Friedrich Wilhelm August (1843). "Uranometria nova: stellae per mediam europam solis oculis conspicuae secundum veras lucis magnitudines e coelo ipso descriptae = Neue Uranometrie: Darstellung der im mittlern Europa mit blossen Augen sichtbaren Sterne nach ihren wahren, unmittelbar vom Himmel entnommenen Grössen / Fr. Argelander". Uranometria Nova: Stellae per Mediam Europam Solis Oculis Conspicuae Secundum Veras Lucis Magnitudines e Coelo Ipso Descriptae = Neue Uranometrie: Darstellung der Im Mittlern Europa mit Blossen Augen Sichtbaren Sterne Nach Ihren Wahren (Schropp). doi:10.3931/e-rara-559. Bibcode: 1843urno.book.....A. 
  16. ↑ Wagman, Morton (2003). Lost Stars: Lost, Missing and Troublesome Stars from the Catalogues of Johannes Bayer, Nicholas Louis de Lacaille, John Flamsteed, and Sundry Others. Blacksburg, VA: The McDonald & Woodward Publishing Company. pp. 73–74. ISBN 978-0-939923-78-6. 
  17. ↑ Wagman, p. 504.
  18. ↑ Kaltcheva, N. T. (2000). "The region of Collinder 121". Monthly Notices of the Royal Astronomical Society 318 (4): 1023–35. doi:10.1046/j.1365-8711.2000.03689.x. Bibcode: 2000MNRAS.318.1023K. 
  19. ↑ Stencel, R. E.; Ueta, T.; Wall, R. J.; Yamamura, I. (2009). "Preliminary Study of Red Supergiant Star Membership in OB Star Associations of the Milky Way". AKARI 418: 459. Bibcode: 2009ASPC..418..459S. 
  20. ↑ Van Leeuwen, F. (2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics 474 (2): 653–664. doi:10.1051/0004-6361:20078357. Bibcode: 2007A&A...474..653V. 
  21. ↑ Toalá, J. A. et al. (2015). "WISE morphological study of Wolf-Rayet nebulae". Astronomy & Astrophysics 578: A66. doi:10.1051/0004-6361/201525706. ISSN 0004-6361. Bibcode: 2015A&A...578A..66T. 
  22. ↑ "Hipparcos Tools Interactive Data Access". ESA. https://www.cosmos.esa.int/web/hipparcos/interactive-data-access. 



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