Observation data Epoch J2000 Equinox J2000 | |
---|---|
Constellation | Ara |
Right ascension | 16h 47m 04.69s [1] |
Declination | −45° 51′ 23.9″ [1] |
Characteristics | |
Evolutionary stage | Red supergiant |
Spectral type | M3 [2] - M6I [3] |
Apparent magnitude (J) | 6.378 |
Apparent magnitude (H) | 4.381 |
Apparent magnitude (K) | 2.61 |
Astrometry | |
Proper motion (μ) |
RA: −2.478
[4]
mas/
yr Dec.: −4.041 [4] mas/ yr |
Parallax (π) | 0.1690 ± 0.1073 mas [4] |
Distance | 2,600+600 −400 (assumed) [5] pc |
Details | |
Radius | 858±48 [2] R☉ |
Luminosity | 101,000±13,000 [2] L☉ |
Temperature | 3,284 - 3,550 [2] K |
Other designations | |
Westerlund 1 W20, Westerlund 1 BKS D,
2MASS J16470468-4551238, Gaia EDR3 5940106007092341120 | |
Database references | |
SIMBAD | data |
Westerlund 1-20 (abbreviated to Wd 1-20 or just W20) is a red supergiant (RSG) located in the Westerlund 1 super star cluster. Its radius was calculated to be around 965 solar radii [1] (6.72 × 108 km, 4.48 au), making it one of the largest stars discovered so far. This corresponds to a volume 899 million times bigger than the Sun. If placed at the center of the Solar System, the photosphere of Westerlund 1-20 would almost reach the orbit of Jupiter.
The star is classified as a luminous cool supergiant emitting most of its energy in the infrared spectrum. [6] W20 occupies the upper right corner of the Hertzsprung-Russell diagram. Using the effective temperature of 3,500 K, [1] the bolometric luminosity of 126,000 L☉ [1] and the solar effective temperature of 5,772 K, [7] its radius can be calculated using the Stefan-Boltzmann law. [a]
Westerlund 1-20 was observed to have an extended, cometary shaped nebula, similar to the other red supergiant Westerlund 1 W26. It is therefore likely that its morphology was affected by either the intracluster medium or the cluster wind of Westerlund 1. [8] The nebulae of both Westerlund 1-20 and Westerlund 1 W26 are extended outward from the cluster core and most bright at inward direction, indicating the outward cluster wind. [9]
Observation data Epoch J2000 Equinox J2000 | |
---|---|
Constellation | Ara |
Right ascension | 16h 47m 04.69s [1] |
Declination | −45° 51′ 23.9″ [1] |
Characteristics | |
Evolutionary stage | Red supergiant |
Spectral type | M3 [2] - M6I [3] |
Apparent magnitude (J) | 6.378 |
Apparent magnitude (H) | 4.381 |
Apparent magnitude (K) | 2.61 |
Astrometry | |
Proper motion (μ) |
RA: −2.478
[4]
mas/
yr Dec.: −4.041 [4] mas/ yr |
Parallax (π) | 0.1690 ± 0.1073 mas [4] |
Distance | 2,600+600 −400 (assumed) [5] pc |
Details | |
Radius | 858±48 [2] R☉ |
Luminosity | 101,000±13,000 [2] L☉ |
Temperature | 3,284 - 3,550 [2] K |
Other designations | |
Westerlund 1 W20, Westerlund 1 BKS D,
2MASS J16470468-4551238, Gaia EDR3 5940106007092341120 | |
Database references | |
SIMBAD | data |
Westerlund 1-20 (abbreviated to Wd 1-20 or just W20) is a red supergiant (RSG) located in the Westerlund 1 super star cluster. Its radius was calculated to be around 965 solar radii [1] (6.72 × 108 km, 4.48 au), making it one of the largest stars discovered so far. This corresponds to a volume 899 million times bigger than the Sun. If placed at the center of the Solar System, the photosphere of Westerlund 1-20 would almost reach the orbit of Jupiter.
The star is classified as a luminous cool supergiant emitting most of its energy in the infrared spectrum. [6] W20 occupies the upper right corner of the Hertzsprung-Russell diagram. Using the effective temperature of 3,500 K, [1] the bolometric luminosity of 126,000 L☉ [1] and the solar effective temperature of 5,772 K, [7] its radius can be calculated using the Stefan-Boltzmann law. [a]
Westerlund 1-20 was observed to have an extended, cometary shaped nebula, similar to the other red supergiant Westerlund 1 W26. It is therefore likely that its morphology was affected by either the intracluster medium or the cluster wind of Westerlund 1. [8] The nebulae of both Westerlund 1-20 and Westerlund 1 W26 are extended outward from the cluster core and most bright at inward direction, indicating the outward cluster wind. [9]