It was given the variable star designation VY Canis Majoris in 1939, the 43rd variable star of the constellation Canis Major. The variation in the star's brightness was first described in 1931, when it was listed (in German) as a long-period variable with a photographic magnitude range of 9.5 to 11.5. Molecules, such as HCN, NaCl, PN, CH, CO, CHĢ have been detected. Giving spectral lines in brackets, the star is a strong emitter of OH (1612 MHz), HĢO (22235.08 MHz), and SiO (43122 MHz) masers, which has been proven to be typical of an OH/IR star. Observations in 1957 and high-resolution imaging in 1998 all but rule out any companion stars. These are now known to be bright zones in the host nebula. During the 19th century, observers measured at least six discrete components, suggesting that it might be a multiple star. Since 1847, VY Canis Majoris has been described as a crimson star. Further quite frequent studies of its apparent magnitude imply the light of the star as viewed from Earth has faded since 1850, which could be due to emission changes or a denser part of its surrounds becoming interposed ( extinction). The first known-recorded observation of VY Canis Majoris is in the star catalogue of the French astronomer Jérôme Lalande in 1801, which lists it as a 7th order of magnitude star. Observational history Portrait in bust of Jérôme Lalande in 1802 If this star replaced the Sun its surface would, per this approximation, be beyond the orbit of Jupiter. 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. 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. 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 produces strong molecular maser emission and was one of the first radio masers discovered. ![]() ![]() ![]() It is surrounded by a complex asymmetric circumstellar envelope (CSE) caused by its mass loss. It is about 17 ☘ times the mass of the Sun ( M ☉). 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. No evidence has been found that it is part of a multiple star system. 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. VY Canis Majoris (abbreviated to VY CMa) is an extreme oxygen-rich (O-rich) red hypergiant (RHG) or red supergiant (RSG) and pulsating variable star 1.2 kiloparsecs (3,900 light-years) from the Solar System in the slightly southern constellation of Canis Major.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |