| absmag_v = –5.14[12]
}}{{Starbox detail
| mass = {{nowrap|12.3 ± 0.1}}[13]
| radius = 420[12]
| luminosity = 31,000[12]
| temperature = 3,750[12]
| gravity = 1.00[17]
| metal_fe = +0.16[17]
| rotational_velocity =
| age_myr = {{nowrap|16.4 ± 0.5}}[13]
}}{{Starbox catalog
| names = Unurgunite, 22 Canis Majoris, ADS 5719, CD −27°3544, FK5 1183, HD 52877, HIP 33856, HR 2646, SAO 172797.[20]
}}{{Starbox reference
| Simbad=Sigma+CMa
}}{{Starbox end}}Sigma Canis Majoris (σ Canis Majoris, abbreviated Sigma CMa, σ CMa), also named Unurgunite,[1] is a variable star in the southern constellation of Canis Major. It is approximately {{Convert|1120|ly|pc|abbr=off|lk=on}} from the Sun and has an average apparent visual magnitude of +3.41.
Nomenclature
σ Canis Majoris (Latinised to Sigma Canis Majoris) is the system's Bayer designation. The star bore the traditional name of Unurgunite in the culture of the Boorong, a clan of the indigenous Maligundidj people of northwestern Victoria in Australia, who saw it as an ancestral figure who fights the moon, flanked by his wives (the stars Delta and Epsilon Canis Majoris).[2][3] In 2016, the International Astronomical Union organized a Working Group on Star Names (WGSN)[4] to catalog and standardize proper names for stars. The WGSN approved the name Unurgunite for this star on 5 September 2017 and it is now so included in the List of IAU-approved Star Names.[1] Properties
Sigma Canis Majoris is a supergiant star with a stellar classification of K4 III. 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.[12] At 1.95 Astronomical units,[27] this radius is nearly double the average distance of the Earth from the Sun. It is currently radiating about 32,000[28] times the luminosity of the Sun from its outer envelope at an effective temperature of around 3,877 K.[17] This gives it the cool orange-red hue of an M-type star.[30]
Variability
Sigma Canis Majoris was noted as a likely variable star in a list of bright southern stars studied at the Cape Observatory.[31] The variability was confirmed in 1963,[32] and it was formally catalogued as a variable star.[33]
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.[34] It is suspected of being a member of the Collinder 121 stellar association of co-moving stars,[12] but this is disputed.[36]
Pre-supernova
Sigma Canis Majoris is listed as a possible type II supernova. Instruments are capable of measuring the pre-supernova neutrino flux which would act as an alert that the supernova explosion was starting.[37]
References
1. ^1 {{cite web | url=https://www.iau.org/public/themes/naming_stars/ | title=Naming Stars |publisher=IAU.org |accessdate=16 December 2017}}
2. ^1 {{cite journal|author=Hamacher, Duane W.|author2=Frew, David J. |date=2010|title= An Aboriginal Australian Record of the Great Eruption of Eta Carinae|journal=Journal of Astronomical History & Heritage |volume=13|issue=3|pages= 220–34|url=https://arxiv.org/ftp/arxiv/papers/1010/1010.4610.pdf|bibcode=2010JAHH...13..220H |arxiv = 1010.4610 }}
3. ^{{cite press release |url=https://www.iau.org/news/pressreleases/detail/iau1707/ |title=IAU Approves 86 New Star Names From Around the World |publisher=IAU.org |date=11 December 2017}}
4. ^{{cite web | url=https://www.iau.org/science/scientific_bodies/working_groups/280/ | title=IAU Working Group on Star Names (WGSN)|accessdate=22 May 2016}}
5. ^1 2 3 {{citation | last1=Mallik | first1=Sushma V. | title=Chromospheric activity in cool stars and the lithium abundance | journal=Astronomy and Astrophysics | volume=338 | pages=623–636 |date=October 1998 | bibcode=1998A&A...338..623M }}
6. ^1 {{citation | last1=Mermilliod | first1=J. C. | last2=Mayor | first2=M. | last3=Udry | first3=S. | title=Red giants in open clusters. XIV. Mean radial velocities for 1309 stars and 166 open clusters | journal=Astronomy and Astrophysics | volume=485 | issue=1 | pages=303–314 |date=July 2008 | doi=10.1051/0004-6361:200809664 | bibcode=2008A&A...485..303M | citeseerx=10.1.1.30.7545 }}
7. ^1 {{citation | display-authors=1 | last1=Grunhut | first1=J. H. | last2=Wade | first2=G. A. | last3=Hanes | first3=D. A. | last4=Alecian | first4=E. | title=Systematic detection of magnetic fields in massive, late-type supergiants | journal=Monthly Notices of the Royal Astronomical Society | volume=408 | issue=4 | pages=2290–2297 |date=November 2010 | doi=10.1111/j.1365-2966.2010.17275.x | bibcode=2010MNRAS.408.2290G |arxiv = 1006.5891 }}
8. ^1 {{citation | last1=Mallik | first1=Sushma V. | title=Lithium abundance and mass | journal=Astronomy and Astrophysics | volume=352 | pages=495–507 |date=December 1999 | bibcode=1999A&A...352..495M }}
9. ^1 {{citation | display-authors=1 | last1=de Zeeuw | first1=P. T. | last2=Hoogerwerf | first2=R. | last3=de Bruijne | first3=J. H. J. | last4=Brown | first4=A. G. A. | last5=Blaauw | first5=A. | title=A HIPPARCOS Census of the Nearby OB Associations | journal=The Astronomical Journal | volume=117 | issue=1 | pages=354–399 |date=January 1999 | doi=10.1086/300682 | bibcode=1999AJ....117..354D |arxiv = astro-ph/9809227 }}
10. ^1 {{citation | title=The Colour of Stars | date=December 21, 2004 | work=Australia Telescope, Outreach and Education | publisher=Commonwealth Scientific and Industrial Research Organisation | url=http://outreach.atnf.csiro.au/education/senior/astrophysics/photometry_colour.html | accessdate=2012-01-16 }}
11. ^1 2 3 4 5 6 {{citation | display-authors=1 | author1-link=Emily Levesque | last1=Levesque | first1=Emily M. | last2=Massey | first2=Philip | last3=Olsen | first3=K. A. G. | last4=Plez | first4=Bertrand | last5=Josselin | first5=Eric | last6=Maeder | first6=Andre | last7=Meynet | first7=Georges | title=The Effective Temperature Scale of Galactic Red Supergiants: Cool, but Not As Cool As We Thought | journal=The Astrophysical Journal | volume=628 | issue=2 | pages=973–985 |date=August 2005 | doi=10.1086/430901 | bibcode=2005ApJ...628..973L |arxiv = astro-ph/0504337 }}
12. ^1 2 {{citation | last1=Tetzlaff | first1=N. | last2=Neuhäuser | first2=R. | last3=Hohle | first3=M. M. | title=A catalogue of young runaway Hipparcos stars within 3 kpc from the Sun | journal=Monthly Notices of the Royal Astronomical Society | volume=410 | issue=1 | pages=190–200 |date=January 2011 | doi=10.1111/j.1365-2966.2010.17434.x | bibcode=2011MNRAS.410..190T |arxiv = 1007.4883 }}
13. ^1 1 solar radius = 0.0046491 Astronomical Units, so 420 × 0.00465 = 1.95.
14. ^1 {{cite journal|bibcode=2016ApJ...818...91A|arxiv=1506.01175|title=KamLAND Sensitivity to Neutrinos from Pre-supernova Stars|journal=The Astrophysical Journal|volume=818|pages=91|author1=Asakura|first1=K.|last2=Gando|first2=A.|last3=Gando|first3=Y.|last4=Hachiya|first4=T.|last5=Hayashida|first5=S.|last6=Ikeda|first6=H.|last7=Inoue|first7=K.|last8=Ishidoshiro|first8=K.|last9=Ishikawa|first9=T.|last10=Ishio|first10=S.|last11=Koga|first11=M.|last12=Matsuda|first12=S.|last13=Mitsui|first13=T.|last14=Motoki|first14=D.|last15=Nakamura|first15=K.|last16=Obara|first16=S.|last17=Oura|first17=T.|last18=Shimizu|first18=I.|last19=Shirahata|first19=Y.|last20=Shirai|first20=J.|last21=Suzuki|first21=A.|last22=Tachibana|first22=H.|last23=Tamae|first23=K.|last24=Ueshima|first24=K.|last25=Watanabe|first25=H.|last26=Xu|first26=B. D.|last27=Kozlov|first27=A.|last28=Takemoto|first28=Y.|last29=Yoshida|first29=S.|last30=Fushimi|first30=K.|display-authors=29|year=2016|doi=10.3847/0004-637X/818/1/91}}
15. ^1 2 {{cite journal|bibcode=2002yCat.2237....0D|title=VizieR Online Data Catalog: Catalogue of Stellar Photometry in Johnson's 11-color system|journal=CDS/ADC Collection of Electronic Catalogues|volume=2237|pages=0|author1=Ducati|first1=J. R.|year=2002}}
16. ^1 {{cite journal|bibcode=1951Obs....71..199C|title=Bright variable stars in southern hemisphere (first list)|journal=The Observatory|volume=71|pages=199|author1=Cousins|first1=A. W. J.|year=1951}}
17. ^1 {{cite journal|bibcode=1963MNSSA..22..133C|title=Red Variable Stars of Small Range Amongst the Bright Stars|journal=Monthly Notes of the Astron. Soc. Southern Africa|volume=22|pages=133|author1=Cousins|first1=A. W. J.|year=1963}}
18. ^1 {{cite journal|bibcode=1973IBVS..834....1K|title=59th Name-List of Variable Stars|journal=Information Bulletin on Variable Stars|volume=834|pages=1|author1=Kukarkin|first1=B. V.|last2=Kholopov|first2=P. N.|last3=Kukarkina|first3=N. P.|last4=Perova|first4=N. B.|year=1973}}
19. ^1 {{cite journal|bibcode=2008ApJS..176..216A|title=Visual Multiples. IX. MK Spectral Types|journal=The Astrophysical Journal Supplement Series|volume=176|pages=216–217|author1=Abt|first1=Helmut A|year=2008|doi=10.1086/525529}}
20. ^1 2 {{cite journal|bibcode=2009yCat....102025S|title=VizieR Online Data Catalog: General Catalogue of Variable Stars (Samus+ 2007-2013)|journal=VizieR On-line Data Catalog: B/gcvs. Originally published in: 2009yCat....102025S|volume=1|pages=02025|author1=Samus|first1=N. N.|last2=Durlevich|first2=O. V.|year=2009|display-authors=etal}}
Note: see VizieR catalogue I/311.