VY Canis Majoris

VY Canis Majoris
Location of VY CMa (circled in red)
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Canis Major
Right ascension 07h 22m 58.32877s[1]
Declination −25° 46′ 03.2355″[1]
Apparent magnitude (V) 6.5–9.6[2]
Characteristics
Evolutionary stage Red hypergiant
Spectral type M3–M4.5[3] (M2.5[4]–M5Iae[5])
Apparent magnitude (U) 12.01[6]
Apparent magnitude (B) 10.19[6]
Apparent magnitude (V) 7.95[6]
Apparent magnitude (J) 1.98[6]
Apparent magnitude (H) 0.44[6]
Apparent magnitude (K) -0.72[6]
U−B color index +2.32[7]
B−V color index +2.057[1]
V−R color index +2.20[7]
Variable type SRc[2] or Lc[8]
Astrometry
Radial velocity (Rv)41[9] km/s
Proper motion (μ) RA: 9.84[1] mas/yr
Dec.: 0.75[1] mas/yr
Parallax (π)0.83 ± 0.08 mas[10]
Distance~3,820+260
−230 ly
(1,170+80
−70[3] pc)
Details
Mass17±8[3] M☉
Radius1,420±120[3][11] R☉
Luminosity270,000±40,000,[3][12] 178,000+40,900
−29,900[13] L☉
Surface gravity (log g)−0.6±0.4[3] cgs
Temperature3,490±90[3] K
Metallicity [Fe/H]+0.0[12][a] dex
Rotational velocity (v sin i)300[10] km/s
Age8.2[10] Myr
Other designations
VY CMa, HD 58061, HIP 35793, CD-25 4441, AAVSO 0718-25, IRAS 07209-2540, IRC −30087, RAFGL 1111, SAO 173571, WDS J07230-2546AB, 2MASS J07225830-2546030
Database references
SIMBADdata

VY Canis Majoris (abbreviated to VY CMa) is an extreme oxygen-rich red hypergiant or red supergiant (O-rich RHG or RSG) and pulsating variable star 1.2 kiloparsecs (3,900 light-years) from the Solar System in the slightly southern constellation of Canis Major. It is one of the largest known stars, one of the most luminous and massive red supergiants, and one of the most luminous stars in the Milky Way.

No evidence has been found that it is part of a multiple star system. Its great infrared (IR) excess makes it one of the brightest objects in the local part of the galaxy at wavelengths of 5 to 20 microns (μm) and indicates a dust shell or heated disk.[14][15] It is about 17±8 times the mass of the Sun (M☉). It is surrounded by a complex asymmetric circumstellar envelope (CSE) caused by its mass loss. It produces strong molecular maser emission and was one of the first radio masers discovered. VY CMa is embedded in the large molecular cloud Sh2-310, a large, quite local star-forming H II region—its diameter: 480 arcminutes (′) or 681 ly (209 pc).[16][17]

The radius of VY CMa is very roughly 1,420 times that of the Sun (R☉), which is close to the modelled maximum, the Hayashi limit, a volume nearly 3 billion times that of the Sun.[3] Taking this mid-point estimate as correct, an object travelling at the speed of light would take 6 hours to go around its surface, compared to 14.5 seconds for the Sun.[18] If this star replaced the Sun its surface would, per this approximation, be beyond the orbit of Jupiter.[3]

  1. ^ a b c d e Cite error: The named reference hipparcos was invoked but never defined (see the help page).
  2. ^ a b Cite error: The named reference GCVS-VY-CMa was invoked but never defined (see the help page).
  3. ^ a b c d e f g h i Cite error: The named reference Wittkowski_vlti was invoked but never defined (see the help page).
  4. ^ Cite error: The named reference massey2006 was invoked but never defined (see the help page).
  5. ^ Cite error: The named reference LipscyJura2005 was invoked but never defined (see the help page).
  6. ^ a b c d e f Cite error: The named reference flux was invoked but never defined (see the help page).
  7. ^ a b Cite error: The named reference chicago1969 was invoked but never defined (see the help page).
  8. ^ Cite error: The named reference AAVSO-VY-CMa was invoked but never defined (see the help page).
  9. ^ Cite error: The named reference ejecta was invoked but never defined (see the help page).
  10. ^ a b c Cite error: The named reference zhang was invoked but never defined (see the help page).
  11. ^ Cite error: The named reference gordon2019 was invoked but never defined (see the help page).
  12. ^ a b Cite error: The named reference kaminski2019 was invoked but never defined (see the help page).
  13. ^ Cite error: The named reference Davies2020 was invoked but never defined (see the help page).
  14. ^ Cite error: The named reference Nathan2001 was invoked but never defined (see the help page).
  15. ^ Cite error: The named reference herbig was invoked but never defined (see the help page).
  16. ^ Cite error: The named reference Sh2-310 was invoked but never defined (see the help page).
  17. ^ Cite error: The named reference sharpless was invoked but never defined (see the help page).
  18. ^ Cite error: The named reference SSE was invoked but never defined (see the help page).


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