Sigma Canis Majoris

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Sigma Canis Majoris
Diagram showing star positions and boundaries of the Canis Major constellation and its surroundings
Cercle rouge 100%.svg

Location of σ Canis Majoris (circled)
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
22 Canis Majoris, ADS 5719, CD −27° 3544, FK5 1183, HD 52877, HIP 33856, HR 2646, SAO 172797, Unurgunite.[10]
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. ↑ 1.0 1.1 1.2 1.3 1.4 Lua error in package.lua at line 80: module 'strict' not found. Note: see VizieR catalogue I/311.
  2. ↑ 2.0 2.1 2.2 Lua error in package.lua at line 80: module 'strict' not found.
  3. ↑ 3.0 3.1 3.2 Lua error in package.lua at line 80: module 'strict' not found.
  4. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  5. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  6. ↑ 6.0 6.1 6.2 6.3 Lua error in package.lua at line 80: module 'strict' not found.
  7. ↑ 7.0 7.1 Lua error in package.lua at line 80: module 'strict' not found.
  8. ↑ 8.0 8.1 Lua error in package.lua at line 80: module 'strict' not found.
  9. ↑ 9.0 9.1 9.2 9.3 Lua error in package.lua at line 80: module 'strict' not found.
  10. ↑ 10.0 10.1 Lua error in package.lua at line 80: module 'strict' not found.
  11. ↑ 1 solar radius = 0.0046491 Astronomical Units, so 420 × 0.00465 = 1.95.
  12. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  13. ↑ Lua error in package.lua at line 80: module 'strict' not found.
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