Westerlund 1-20

Westerlund 1-20 or Wd 1-20 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.

Westerlund 1-20 compared to the other 3 RSGs in the Westerlund 1 star cluster.

Westerlund 1-20
Westerlund 1 super star cluster. The location of Wd 1-20 is circled.
Credit: ESO
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 M6I
Apparent magnitude (J) 6.378
Apparent magnitude (H) 4.381
Apparent magnitude (K) 2.61
Astrometry
Proper motion (μ) RA: -1.671[2] mas/yr
Dec.: -3.818[2] mas/yr
Parallax (π)0.2606 ± 0.2579[2] mas
Distanceapprox. 10,000 ly
(approx. 4,000 pc)
Details
Radius965[1] R☉
Luminosity126,000[1] L☉
Temperature3,500[1] K
Other designations
Westerlund 1 W20, Westerlund 1 BKS D, 2MASS J16470468-4551238
Database references
SIMBADdata

The star is classified as a luminous cool supergiant emitting most of its energy in the infrared spectrum[3]. 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[4], its 1-20 can be calculated using the Stefan-Boltzmann law.[lower-alpha 1]

Westerlund 1-20 was observed to have an extended, cometary shaped nebula, similar to the other red supergiant Westerlund 1-26. It is therefore likely that its morphology was affected by either the intracluster medium or the cluster wind of Westerlund 1.[5]

See also

Notes

References
  1. Fok, Thomas K. T.; Nakashima, Jun-Ichi; Yung, Bosco H. K.; Hsia, Chih-Hao; Deguchi, Shuji (2012). "Maser Observations of Westerlund 1 and Comprehensive Considerations on Maser Properties of Red Supergiants Associated with Massive Clusters". The Astrophysical Journal. 760 (1): 65. arXiv:1209.6427. Bibcode:2012ApJ...760...65F. doi:10.1088/0004-637X/760/1/65.
  2. Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR.
  3. "Cl* Westerlund 1 W 20". Simbad.
  4. Williams, D. R. (2013). "Sun Fact Sheet".
  5. Dougherty, S. M.; Clark, J. S.; Negueruela, I.; Johnson, T.; Chapman, J. M. (2010-02-01). "Radio emission from the massive stars in the galactic super star cluster Westerlund 1". Astronomy & Astrophysics. 511: A58. doi:10.1051/0004-6361/200913505. ISSN 0004-6361.
This article is issued from Wikipedia. The text is licensed under Creative Commons - Attribution - Sharealike. Additional terms may apply for the media files.