Sigma Canis Majoris
| |
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Canis Major |
| Right ascension | 07h 01m 43.14779s[1] |
| Declination | –27° 56′ 05.3898″[1] |
| Apparent magnitude (V) | +3.47[2] |
| Characteristics | |
| Spectral type | M1.5 Iab[3] |
| U−B color index | +1.88[2] |
| B−V color index | +1.73[2] |
| Variable type | LC[4] |
| Astrometry | |
| Radial velocity (Rv) | +22.11[5] km/s |
| Proper motion (μ) | RA: –5.98[1] mas/yr Dec.: +4.59[1] mas/yr |
| Parallax (π) | 2.91 ± 0.19[1] mas |
| Distance | 1,120 ± 70 ly (340 ± 20 pc) |
| Absolute magnitude (MV) | –5.14[6] |
| Details | |
| Mass | 12.3 ± 0.1[7] M☉ |
| Radius | 420[6] R☉ |
| Luminosity | 32,000[8] L☉ |
| Surface gravity (log g) | 1.00[9] cgs |
| Temperature | 3,877[9] K |
| Metallicity [Fe/H] | +0.16[9] dex |
| Age | 16.4 ± 0.5[7] Myr |
| Other designations | |
| Database references | |
| SIMBAD | data |
Sigma Canis Majoris (σ CMa, σ Canis Majoris) is a star in the southern constellation of Canis Major. It is approximately 1,120 light-years (340 parsecs) from Earth and has an average apparent visual magnitude of +3.41.
σ CMa is a supergiant star with a stellar classification of M1.5 Iab.[3] This is a type of star that is in the late stages of its evolution, having consumed the hydrogen at its core and ballooned out to 420 times the Sun's radius.[6] At 1.95 Astronomical Units,[11] this radius is nearly double the average distance of the Earth from the Sun. It is currently radiating about 32,000[8] times the luminosity of the Sun from its outer envelope at an effective temperature of around 3,877 K.[9] This gives it the cool orange-red hue of an M-type star.[12]
It is classified as an irregular variable star and its brightness varies from magnitude +3.43 to +3.51. The magnetic field of this star has a strength below 1 G.[3] It is suspected of being a member of the Collinder 121 stellar association of co-moving stars,[6] but this is disputed.[13]
Culture signification
The indigenous Boorong people of northwestern Victoria saw it as Unurgunite, flanked by his wives (Epsilon and Delta Canis Majoris).[10]
References
- 1 2 3 4 5 van Leeuwen, Floor (November 2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics, 474 (2): 653–664, arXiv:0708.1752v1
, Bibcode:2007A&A...474..653V, doi:10.1051/0004-6361:20078357 Note: see VizieR catalogue I/311. - 1 2 3 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: 0. Bibcode:2002yCat.2237....0D.
- 1 2 3 Grunhut, J. H.; et al. (November 2010), "Systematic detection of magnetic fields in massive, late-type supergiants", Monthly Notices of the Royal Astronomical Society, 408 (4): 2290–2297, arXiv:1006.5891, Bibcode:2010MNRAS.408.2290G, doi:10.1111/j.1365-2966.2010.17275.x
- ↑ 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.
- ↑ Mermilliod, J. C.; Mayor, M.; Udry, S. (July 2008), "Red giants in open clusters. XIV. Mean radial velocities for 1309 stars and 166 open clusters", Astronomy and Astrophysics, 485 (1): 303–314, Bibcode:2008A&A...485..303M, doi:10.1051/0004-6361:200809664
- 1 2 3 4 Levesque, Emily M.; et al. (August 2005), "The Effective Temperature Scale of Galactic Red Supergiants: Cool, but Not As Cool As We Thought", The Astrophysical Journal, 628 (2): 973–985, arXiv:astro-ph/0504337, Bibcode:2005ApJ...628..973L, doi:10.1086/430901
- 1 2 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
- 1 2 Mallik, Sushma V. (December 1999), "Lithium abundance and mass", Astronomy and Astrophysics, 352: 495–507, Bibcode:1999A&A...352..495M
- 1 2 3 4 Mallik, Sushma V. (October 1998), "Chromospheric activity in cool stars and the lithium abundance", Astronomy and Astrophysics, 338: 623–636, Bibcode:1998A&A...338..623M
- 1 2 Hamacher, Duane W.; Frew, David J. (2010). "An Aboriginal Australian Record of the Great Eruption of Eta Carinae" (PDF). Journal of Astronomical History & Heritage. 13 (3): 220–34. arXiv:1010.4610. Bibcode:2010JAHH...13..220H.
- ↑ 1 solar radius = 0.0046491 Astronomical Units, so 420 × 0.00465 = 1.95.
- ↑ "The Colour of Stars", Australia Telescope, Outreach and Education, Commonwealth Scientific and Industrial Research Organisation, December 21, 2004, retrieved 2012-01-16
- ↑ de Zeeuw, P. T.; et al. (January 1999), "A HIPPARCOS Census of the Nearby OB Associations", The Astronomical Journal, 117 (1): 354–399, arXiv:astro-ph/9809227, Bibcode:1999AJ....117..354D, doi:10.1086/300682