VY Canis Majoris
| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Canis Major |
| Right ascension | 07h 22m 58.32877s |
| Declination | −25° 46′ 03.2355″ |
| Apparent magnitude (V) | 6.5–9.6 |
| Characteristics | |
| Evolutionary stage | RHG or ERSG (OH/IR) |
| Spectral type | M3–M4.5 (M2.5–M5Iae) |
| Apparent magnitude (U) | 12.01 |
| Apparent magnitude (B) | 10.19 |
| Apparent magnitude (V) | 7.95 |
| Apparent magnitude (J) | 1.98 |
| Apparent magnitude (H) | 0.44 |
| Apparent magnitude (K) | -0.72 |
| U−B color index | +2.32 |
| B−V color index | +2.057 |
| V−R color index | +2.20 |
| Variable type | SRc or Lc |
| Astrometry | |
| Radial velocity (Rv) | 41 km/s |
| Proper motion (μ) | RA: −2.8±0.2 mas/yr Dec.: +2.6±0.2 mas/yr |
| Parallax (π) | 0.83±0.08 mas |
| Distance | 3,820+260 −230 ly (1,170+80 −70 pc) |
| Details | |
| Mass | 17±8 M☉ |
| Radius | 1,420±120 R☉ |
| Luminosity | 270,000±40,000, 178,000+40,900 −29,900 L☉ |
| Surface gravity (log g) | −0.6±0.4 cgs |
| Temperature | 3,490±90 K |
| Metallicity [Fe/H] | +0.0 dex |
| Age | 8.2 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 | |
| SIMBAD | data |
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 (Orion Arm) at wavelengths of 5 to 20 microns (μm) and indicates a dust shell or heated disk. 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). It has been described as 'Betelgeuse on steroids'.
The radius of VY CMa is estimated at 1,420 times that of the Sun (R☉), which is close to the modelled maximum, the Hayashi limit, corresponding to a volume almost 3 billion times that of the Sun. At this radius, 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. If this star replaced the Sun its surface would expand beyond the orbit of Jupiter.