V4650 Sagittarii (qF362) is a

luminous blue variable star Luminous blue variables (LBVs) are massive evolved stars that show unpredictable and sometimes dramatic variations in their spectra and brightness. They are also known as S Doradus variables after S Doradus, one of the brightest stars of the Large ...

(LBV) in the constellation of Sagittarius. Located some 25,000 light years away, the star is positioned on the edge of a starburst cluster known as the

Quintuplet cluster The Quintuplet cluster is a dense cluster may refer to: Science and technology Astronomy * Cluster (spacecraft), constellation of four European Space Agency spacecraft * Asteroid cluster, a small asteroid family * Cluster II (spacecraft ...

Discovery

V4650 Sgr was first catalogued in 1996 as star 362 in a list of stars in the galactic centre region near the

Quintuplet Cluster The Quintuplet cluster is a dense cluster may refer to: Science and technology Astronomy * Cluster (spacecraft), constellation of four European Space Agency spacecraft * Asteroid cluster, a small asteroid family * Cluster II (spacecraft ...

. The acronym qF is used for stars in the list and so the star name is qF 362. The acronym FMM is also used, hence FMM 362. The LBV nature of qF 362 was not recognised until 1999. It is one of three LBVs close to the Quintuplet Cluster, all highly luminous stars. V4650 was discovered using

infrared Infrared (IR), sometimes called infrared light, is electromagnetic radiation (EMR) with wavelengths longer than those of visible light. It is therefore invisible to the human eye. IR is generally understood to encompass wavelengths from around ...

telescopes. It is extremely faint at optical wavelengths due to interstellar extinction. The

2MASS The Two Micron All-Sky Survey, or 2MASS, was an astronomical survey of the whole sky in infrared light. It took place between 1997 and 2001, in two different locations: at the U.S. Fred Lawrence Whipple Observatory on Mount Hopkins, Arizona, and ...

survey recorded it at 17th magnitude in red light and 19th magnitude in blue light, while it is a 7th magnitude object in K band infrared.

Properties

V4650 Sgr is calculated to be one of the

most luminous stars This is a list of stars arranged by their absolute magnitude – their intrinsic stellar luminosity. This cannot be observed directly, so instead must be calculated from the apparent magnitude (the brightness as seen from Earth), the distance t ...

known, at to . It is considered to be a bona-fide luminous blue variable, although it has not been observed to change temperature from the S Doradus minimum strip to a cooler outburst state. The infrared brightness has varied between magnitude 7.0 and 7.9. It is calculated to have a temperature of 11,300 K and a radius of . Unlike both the two nearby LBVs, V4650 Sgr has no detectable associated nebulosity.

References

{{DEFAULTSORT:LBV G0.120-0.048 Luminous blue variables Sagittarius (constellation) Sagittarii, V4647 J17461798-2849034