Sigma Canis Majoris
Template:Location mark Location of σ Canis Majoris (circled) | |
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Canis Major |
| Right ascension | Template:RA[1] |
| Declination | Template:DEC[1] |
| Apparent magnitude (V) | 3.43 - 3.51[2] |
| Characteristics | |
| Spectral type | K5 Ib[3] |
| U−B Template:Engvar | +1.88[4] |
| B−V Template:Engvar | +1.73[4] |
| Variable type | LC[2] |
| Astrometry | |
| Radial velocity (Rv) | +22.11[5] km/s |
| Proper motion (μ) | RA: −5.714 mas/yr[6] Dec.: +4.890 mas/yr[6] |
| Parallax (π) | 2.5085±0.1590 mas[6] |
| Distance | Script error: No such module "val". ly (Script error: No such module "val". pc)[7] |
| Absolute magnitude (MV) | −5.14[8] |
| Details | |
| Mass | Script error: No such module "val".,[9] Script error: No such module "val"., Script error: No such module "val".[10] Template:Solar mass |
| Radius | 297[11] Template:Solar radius |
| Luminosity | 15,800[11] Template:Solar luminosity |
| Surface gravity (log g) | 0.32[9] cgs |
| Temperature | Script error: No such module "val".[10] K |
| Metallicity [Fe/H] | +0.16[12] dex |
| Age | 83.2[9] Myr |
| Metallicity [Fe/H] | {{{metal_fe2}}} dex |
| Other designations | |
| Template:Odlist[13] | |
| Database references | |
| SIMBAD | data |
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Sigma Canis Majoris, also named Nganurganity Script error: No such module "IPA".[14] or Unurgunite Template:IPAc-en,[15] is a variable star in the southern constellation of Canis Major. It is approximately Script error: No such module "convert". from the Sun and has an average apparent visual magnitude of +3.41.
Nomenclature
σ Canis Majoris (Latinised to Sigma Canis Majoris, abbreviated Sigma CMa, σ CMa) is the system's Bayer designation.
The star is identified with the nganurganity Script error: No such module "IPA". "Jacky lizard"[16] 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).[17][18] 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)[19] 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.[15] The name was later corrected to "Nganurganity",[20] though since June 2025[update]Template:Dated maintenance category (articles)Script error: No such module "Check for unknown parameters". the current IAU Catalog of Star Names lists both spellings.[14]
Properties
Sigma Canis Majoris is a supergiant star with a stellar classification of K5 Ib.[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 290 times the Sun's radius.[11] At 1.38 astronomical units, this radius is 38% larger than the average distance of the Earth from the Sun.[21] It is currently radiating more than 15,800[11] times the luminosity of the Sun from its outer envelope at an effective temperature of around 3,800 K.[10] This temperature gives it the cool orange-red hue of a late K-type star.[22]
Variability
Sigma Canis Majoris was noted as a likely variable star in a list of bright southern stars studied at the Cape Observatory.[23] The variability was confirmed in 1963,[24] and it was formally catalogued as a variable star.[25]
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.[26] It is suspected of being a member of the Collinder 121 stellar association of co-moving stars,[8] but this is disputed.[27]
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.[28]
References
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- ↑ a b Script error: No such module "citation/CS1". Note: see VizieR catalogue I/311.
- ↑ a b Script error: No such module "Citation/CS1".
- ↑ a b Script error: No such module "citation/CS1". Sigma Canis Majoris' database entry at VizieR.
- ↑ a b Script error: No such module "Citation/CS1".
- ↑ Script error: No such module "citation/CS1".
- ↑ a b Template:Cite Gaia DR3
- ↑ Script error: No such module "Citation/CS1". Data about this star can be seen here.
- ↑ a b Script error: No such module "citation/CS1".
- ↑ a b c Script error: No such module "Citation/CS1". Sigma Canis Majoris' database entry at VizieR.
- ↑ a b c Script error: No such module "Citation/CS1".
- ↑ a b c d Script error: No such module "Citation/CS1".
- ↑ Script error: No such module "citation/CS1".
- ↑ Template:Cite simbad
- ↑ a b Script error: No such module "citation/CS1".
- ↑ a b Script error: No such module "citation/CS1".
- ↑ Literally "waddy-tailed goanna", from nganurr 'black goanna' + gani 'waddy' + genitive suffix -ity/-itj.
- ↑ Script error: No such module "Citation/CS1".
- ↑ Script error: No such module "citation/CS1".
- ↑ Script error: No such module "citation/CS1".
- ↑ Script error: No such module "citation/CS1".
- ↑ 1 solar radius = 0.0046491 Astronomical Units, so 290 × 0.0046491 = 1.38.
- ↑ Script error: No such module "citation/CS1".
- ↑ Script error: No such module "Citation/CS1".
- ↑ Script error: No such module "Citation/CS1".
- ↑ Script error: No such module "Citation/CS1".
- ↑ Script error: No such module "citation/CS1".
- ↑ Script error: No such module "citation/CS1".
- ↑ Script error: No such module "Citation/CS1".
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