Westerlund 1 W237

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Westerlund 1 W237
Surprise Cloud Around Vast Star.jpg
Red circle.svg
Westerlund 1 super star cluster. The location of Wd 1-237 is circled.
Credit: ESO
Observation data
Epoch J2000       Equinox J2000
Constellation Ara
Right ascension 16h 47m 03.1075s
Declination −45° 52′ 18.9572″
Apparent magnitude  (V)19.008 [1]
Characteristics
Evolutionary stage either a red supergiant or a foreground giant [2]
Spectral type M3Ia [3] or M6+ III [4]
Apparent magnitude  (B)22.8[ citation needed ]
Apparent magnitude  (R)13.634 [1]
Apparent magnitude  (G)11.259 [5]
Apparent magnitude  (J)5.075 [6]
Apparent magnitude  (H)3.01 [6]
Apparent magnitude  (K)2.18 [6]
Astrometry
Proper motion (μ)RA: -3.09±0.15 [5]   mas/yr
Dec.: -4.12±0.12 [5]   mas/yr
Parallax (π)0.3370 ± 0.1235  mas [5]
Distance 3,000 [7] or 623 [8]   pc
Absolute magnitude  (MV)–6.96 [9]
Details
if a supergiant
Radius 1,241±70 [9]   R☉
Luminosity 219,000±26,000 [9]   L☉
Temperature 3,550 [9] - 3,605 [8]   K
Age 7.9 [9]   Myr
if a foreground giant
Radius 216 [8]   R☉
Luminosity1,000 [2] or 7,178 – 7,379 [8]   L☉
Temperature 3,605 [8]   K
Other designations
Westerlund 1 W237, Westerlund 1 BKS B, 2MASS J16470309-4552189, Gaia EDR3 5940105904023386752
Database references
SIMBAD data

Westerlund 1 W237, also known as Wd 1-237 or Westerlund 1 BKS B, is a possible red supergiant (RSG) in the constellation of Ara. It is one out of four known red supergiants in the Westerlund 1 super star cluster. As a red supergiant, it would be one of the largest known stars and one of the most luminous of its type. [7]

Contents

Physical characteristics

Westerlund 1 W237 compared to the other 3 RSGs (Red Supergiants) in the Westerlund 1 star cluster. Comparison of Radii of RSGs located in the Westerlund 1 star cluster.png
Westerlund 1 W237 compared to the other 3 RSGs (Red Supergiants) in the Westerlund 1 star cluster.

Westerlund 1 W237 is classified as a luminous cool supergiant emitting most of its energy in the infrared spectrum. [10] It is surrounded by a radio nebula which is similar in mass to those of Westerlund 1-20 and Westerlund 1 W26, and moreover directly comparable to that of VY Canis Majoris. The elliptical structure of this nebula however indicates that it has been less affected by the cluster wind of Westerlund 1 (W20 and W26 have pronounced cometary shaped nebulae). The outflow velocity for the RSG wind is assumed to be around 30 km/s. The nebula itself seems to have a mass of 0.07 M☉ and a radius of about 0.11 parsecs. This results in a kinematic age around 3,600 years and a time averaged mass loss rate of 2×10−5  M☉ per year. [11]

The star occupies the upper right corner of the Hertzsprung-Russell diagram. With an effective temperature of 3,550 K and a bolometric luminosity of 219,000 L☉, the radius of Westerlund 1 W237 would be 1,241 times the solar radius (R☉), making it larger than the orbit of Jupiter. The initial mass of W237 has been calculated from its position relative to theoretical stellar evolutionary tracks to be around 28 M☉ or 32 M☉ for a non-rotating star. [9]

Distance

The distance of Westerlund 1 W237 is assumed to be around 8,500+2,000
−1,300  light years or 2,600+600
−400  parsecs [12] based on it being commonly thought of as a member of the Westerlund 1 star cluster (the elliptical shape of its nebula indicates that it might not be near the center of W1, while other RSGs like W20 and W26 are). [11] Another but older source suggests a similar distance of 3,000±500 parsecs. [7]

Westerlund's 1987 analysis assigned a spectral type of M6+ III to W1-237 and considered it to be a foreground giant with a luminosity only around 1,000 L☉. [2] Gaia Data Release 2 gives a parallax of 1.64±0.2608  mas for W237, implying a distance of 623+139
−96  pc and a luminosity of 7,178–7,379 L☉ with a corresponding radius of 216 R☉. [13] [8] In 2020, the parallax was revised to the much smaller value of 0.3370±0.1235 mas, corresponding to a distance of 2967±1087 pc (9670±3540 ly). [5]

See also

Related Research Articles

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<span class="mw-page-title-main">Westerlund 1</span> Super star cluster in the Milky Way Galaxy

Westerlund 1 is a compact young super star cluster about 3.8 kpc away from Earth. It is thought to be the most massive young star cluster in the Milky Way, and was discovered by Bengt Westerlund in 1961 but remained largely unstudied for many years due to high interstellar absorption in its direction. In the future, it will probably evolve into a globular cluster.

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<span class="mw-page-title-main">MY Cephei</span> Star in the constellation Cepheus

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<span class="mw-page-title-main">S Persei</span> Red supergiant or hypergiant variable star in the constellation Perseus

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<span class="mw-page-title-main">WOH G64</span> Red supergiant in the constellation Dorado

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<span class="mw-page-title-main">Westerlund 1 W26</span> Star in the constellation Ara

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<span class="mw-page-title-main">RS Persei</span> Star in the constellation Perseus

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<span class="mw-page-title-main">Westerlund 1-20</span> Red supergiant star located in the Westerlund 1 super star cluster

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 (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.

<span class="mw-page-title-main">Westerlund 1-75</span> Red supergiant in the Westerlund 1 super star cluster

Westerlund 1 W75 or Wd 1-75 is a red supergiant (RSG) located in the Westerlund 1 super star cluster. Its radius is calculated to be around 668 solar radii (4.65 × 108 km, 3.10 au). This corresponds to a volume 298 million times bigger than the Sun. If placed at the center of the Solar System, Westerlund 1-75 would engulf the inner limits of the asteroid belt.

<span class="mw-page-title-main">Trumpler 27-1</span> Red supergiant star in the constellation Scorpius

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<span class="mw-page-title-main">Westerlund 1-243</span> Luminous blue variable star undergoing an eruptive phase in Westerlund 1

Westerlund 1-243 or Wd 1-243 is a luminous blue variable (LBV) star undergoing an eruptive phase located within the outskirts of the super star cluster Westerlund 1. Located about 13,400 ly (4,100 pc) from Earth, it has a luminosity of 0.73 million L☉ making it one of the most luminous stars known.

WR 138a is a Wolf-Rayet star in the constellation Cygnus. It is of a very late spectral type of WN9h. The WR is also at the centre of a ring nebula and is a runaway.

<span class="mw-page-title-main">IRAS 18357–0604</span> Star in the constellation Scutum

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References

  1. 1 2 Bonanos, Alceste Z. (2007). "Variability of Young Massive Stars in the Galactic Super Star Cluster Westerlund 1". The Astronomical Journal. 133 (6): 2696–2708. arXiv: astro-ph/0702614 . Bibcode:2007AJ....133.2696B. doi:10.1086/518093. S2CID   119074868.
  2. 1 2 3 Westerlund, B. E. (1987). "Photometry and spectroscopy of stars in the region of a highly reddened cluster in ARA". Astronomy and Astrophysics. Supplement. 70 (3): 311–324. Bibcode:1987A&AS...70..311W. ISSN   0365-0138.
  3. ↑ Clark, J. S.; Ritchie, B. W.; Negueruela, I. (2010). "A serendipitous survey for variability amongst the massive stellar population of Westerlund 1". Astronomy and Astrophysics. 514: A87. arXiv: 1003.5107 . Bibcode:2010A&A...514A..87C. doi:10.1051/0004-6361/200913820. S2CID   14780809.
  4. ↑ Bonanos, Alceste Z. (2007). "Variability of Young Massive Stars in the Galactic Super Star Cluster Westerlund 1". The Astronomical Journal. 133 (6): 2696–2708. arXiv: astro-ph/0702614 . Bibcode:2007AJ....133.2696B. doi:10.1086/518093. S2CID   119074868.
  5. 1 2 3 4 5 Brown, A. G. A.; et al. (Gaia collaboration) (2021). "Gaia Early Data Release 3: Summary of the contents and survey properties". Astronomy & Astrophysics . 649: A1. arXiv: 2012.01533 . Bibcode:2021A&A...649A...1G. doi: 10.1051/0004-6361/202039657 . S2CID   227254300. (Erratum:  doi:10.1051/0004-6361/202039657e). Gaia EDR3 record for this source at VizieR.
  6. 1 2 3 Cutri, Roc M.; Skrutskie, Michael F.; Van Dyk, Schuyler D.; Beichman, Charles A.; Carpenter, John M.; Chester, Thomas; Cambresy, Laurent; Evans, Tracey E.; Fowler, John W.; Gizis, John E.; Howard, Elizabeth V.; Huchra, John P.; Jarrett, Thomas H.; Kopan, Eugene L.; Kirkpatrick, J. Davy; Light, Robert M.; Marsh, Kenneth A.; McCallon, Howard L.; Schneider, Stephen E.; Stiening, Rae; Sykes, Matthew J.; Weinberg, Martin D.; Wheaton, William A.; Wheelock, Sherry L.; Zacarias, N. (2003). "VizieR Online Data Catalog: 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)". CDS/ADC Collection of Electronic Catalogues. 2246: II/246. Bibcode:2003yCat.2246....0C.
  7. 1 2 3 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. S2CID   53393926.
  8. 1 2 3 4 5 6 Messineo, M.; Brown, A. G. A. (2019). "A Catalog of Known Galactic K-M Stars of Class I Candidate Red Supergiants in Gaia DR2". The Astronomical Journal. 158 (1): 20. arXiv: 1905.03744 . Bibcode:2019AJ....158...20M. doi: 10.3847/1538-3881/ab1cbd . S2CID   148571616.
  9. 1 2 3 4 5 6 Arévalo, Aura (2019). The Red Supergiants in the Supermassive Stellar Cluster Westerlund 1 (Thesis). doi: 10.11606/D.14.2019.tde-12092018-161841 .
  10. ↑ "Cl* Westerlund 1 W 237". Simbad.
  11. 1 2 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. arXiv: 0912.4165 . Bibcode:2010A&A...511A..58D. doi:10.1051/0004-6361/200913505. ISSN   0004-6361. S2CID   9792700.
  12. ↑ Aghakhanloo, Mojgan; Murphy, Jeremiah W.; Smith, Nathan; Parejko, John; Díaz-Rodríguez, Mariangelly; Drout, Maria R.; Groh, Jose H.; Guzman, Joseph; Stassun, Keivan G. (2020-02-21). "Inferring the parallax of Westerlund 1 from Gaia DR2". Monthly Notices of the Royal Astronomical Society. 492 (2): 2497–2509. arXiv: 1901.06582 . Bibcode:2020MNRAS.492.2497A. doi:10.1093/mnras/stz3628. ISSN   0035-8711. S2CID   119465620.
  13. ↑ Bailer-Jones, C. A. L.; Rybizki, J.; Fouesneau, M.; Mantelet, G.; Andrae, R. (2018). "Estimating Distance from Parallaxes. IV. Distances to 1.33 Billion Stars in Gaia Data Release 2". The Astronomical Journal. 156 (2): 58. arXiv: 1804.10121 . Bibcode:2018AJ....156...58B. doi: 10.3847/1538-3881/aacb21 . S2CID   119289017.
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