σ Canis Majoris (
Latinised to Sigma Canis Majoris) is the system's
Bayer designation. The star is identified with the nganurganity[ˈŋanuɾˌɡ̊aniɟ̊] "
Jacky lizard"[15] 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).[13][16]
The name was transcribed by settler William Stanbridge as "Unurgunite" in the 1850s. (Initial ng-, which does not occur in English, was typically ignored in transcription of that era.)
In 2016, the
International Astronomical Union organized a
Working Group on Star Names (WGSN)[17] 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.[14]
Properties
Sigma Canis Majoris is a
giant 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 272 times the
Sun's radius. At 1.27
astronomical units,[18] this radius is nearly double the average distance of the Earth from the Sun.[10] It is currently radiating more than 20,000[19] times the
luminosity of the Sun from its outer envelope at an
effective temperature of around 3,710 K.[11] This gives it the cool orange-red hue of an M-type star.[20]
Variability
Sigma Canis Majoris was noted as a likely
variable star in a list of bright southern stars studied at the
Cape Observatory.[21] The variability was confirmed in 1963,[22] and it was formally catalogued as a variable star.[23]
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.[26]
^
abSamus, 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.
^
abDucati, 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.
^
abMallik, 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
solar radius = 0.0046491 Astronomical Units, so 272.15 × 0.00465 = 1.27.
^Mallik, Sushma V. (December 1999), "Lithium abundance and mass", Astronomy and Astrophysics, 352: 495–507,
Bibcode:
1999A&A...352..495M
^"The Colour of Stars", Australia Telescope, Outreach and Education, Commonwealth Scientific and Industrial Research Organisation, December 21, 2004, archived from
the original on 2013-12-03, retrieved 2012-01-16
^Cousins, A. W. J. (1951). "Bright variable stars in southern hemisphere (first list)". The Observatory. 71: 199.
Bibcode:
1951Obs....71..199C.
^Cousins, A. W. J. (1963). "Red Variable Stars of Small Range Amongst the Bright Stars". Monthly Notes of the Astron. Soc. Southern Africa. 22: 133.
Bibcode:
1963MNSSA..22..133C.
^Kukarkin, B. V.; Kholopov, P. N.; Kukarkina, N. P.; Perova, N. B. (1973). "59th Name-List of Variable Stars". Information Bulletin on Variable Stars. 834: 1.
Bibcode:
1973IBVS..834....1K.