Location and Distance
The VY Canis Majoris star is in the constellation of Canis Major. It is located around 3,900 light years or 1.2 kiloparsecs away from the Solar System. Its right ascension is 07h 22m 58.32877s and its declination is −25° 46′ 03.2355″.
Star System, Size and Composition
VY Canis Majoris is one of the largest known stars in the Milky Way, with a radius about 1,420 times that of the Sun and a diameter of 13.2 AU. This makes the star much larger than Betelgeuse and Antares. If it were placed at the centre of our Solar System, the star’s surface would extend well beyond the orbit of Jupiter.
It is classed as a semiregular variable star and has an estimated period of 2,000 days. The star’s mass is around 30 to 40 times that of the Sun, although as a hypergiant, it is losing its mass at a very high rate. This is around 30 times the mass of the Earth every year as it is entering the final stage of its life before exploding as a supernova. The cloud of expelled material, dust and gas, is pushed away by the star’s radiation pressure and it keeps moving outwards.
VY CMa’s brightness is around 270,000 times that of the Sun, making it one of the most luminous members of its class. It has an effective temp below 4,000 K.
No evidence has been found that it is part of a multiple star system. However, VY CMa is embedded in the large molecular cloud Sh2-310, a large, quite local star-forming H II region.
The spectrum of VY Canis Majoris is that of a high luminosity M class star. The hydrogen lines, how-ever, have P Cygni profiles fit for luminous blue variables. The spectrum is dominated by TiO bands whose strengths suggest a classification of M5.
The star’s great infrared 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. It is surrounded by a complex asymmetric circumstellar envelope (CSE) caused by its mass loss.
VY Canis Majoris is surrounded by a large and dense asymmetric red reflection nebula.
VY Canis Majoris was first catalogued by the French astronomer Jérôme Lalande on March 7, 1801. Lalande listed it as a 7th magnitude star.
Other 19th century data revealed that the star has been fading since 1850. At the time, this star was suspected to be a multiple star, but now the objects that were detected by 19th century observers are known to be bright patches in the nebula around the star. The star was confirmed not to have any companions by visual observations in 1957 and imaging in 1998.
VY Canis Majoris is a highly evolved star yet less than 10 million years old. When it explodes, it is large enough to produce a hypernova, or super-luminous supernova. A hypernova produces a much higher amount of energy than regular supernovae, as well as long-duration gamma ray bursts, which are among the most energetic events observed in the universe.
It is likely the remnant of this star will be a black hole rather than a neutron star. This is be-cause it is so large.
- VY Canis Majoris image – https://www.deviantart.com/redblackproductions/art/VY-Canis-Majoris-727131297
- VY Canis Majoris size comp – https://www.universetoday.com/wp-content/uploads/2008/04/vycanis.png