Westerlund 1-75

Westerlund 1-75
	Westerlund 1 super star cluster. The location of Wd 1-75 is circled.; Credit: ESO
Observation data; Epoch J2000 Equinox J2000
Constellation	Ara
Right ascension	16h 47m 08.93s
Declination	−45° 49′ 58.6″
Apparent magnitude (V)	16.7
Characteristics
Evolutionary stage	Red supergiant
Spectral type	M1 - M4Ia
Apparent magnitude (J)	6.933
Apparent magnitude (H)	4.673
Apparent magnitude (K)	3.28
Astrometry
Radial velocity (Rv)	−50.6±2.9 km/s
Proper motion (μ)	RA: −2.029 mas/yr ; Dec.: −4.248 mas/yr
Details
Radius	722±36 R☉
Luminosity	120,000±14,000 L☉
Temperature	3,600 - 4,000 K
Other designations
	Westerlund 1 W75, Westerlund 1 BKS E, 2MASS J16470892-4549585, Gaia EDR3 5940199877892579584
Database references
SIMBAD	data

Coordinates: 16^h 47^m 08.93^s, −45° 49′ 58.45″

Westerlund 1-75 or Wd 1-75 is a red supergiant (RSG) located in the Westerlund 1 super star cluster. Its radius was calculated to be around 668 solar radii^[1] (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.

Westerlund 1-75 compared to the other 3 RSGs in the Westerlund 1 star cluster.

The star is classified as a luminous cool supergiant emitting most of its energy in the infrared spectrum.^[5] It occupies the upper right corner of the Hertzsprung-Russell diagram. Using the effective temperature of 3,600 K,^[1] the bolometric luminosity of 68,000 L_☉^[1] and the solar effective temperature of 5,772 K,^[6] the radius of Westerlund 1-75 can be calculated using the Stefan-Boltzmann law.^[a]

Like Westerlund 1-20, Westerlund 1-26 and Westerlund 1-237, Westerlund 1-75 was observed to be a radio source, however it is weakest along the RSGs in its cluster and remains unresolved at any wavelength.^[7]

Westerlund 1-75 is surrounded by extended nebula, although it appears less massive than nebulae around typical red supergiant stars.^[8]

Notes[]

^ ${\sqrt {\left({\frac {5772}{3600}}\right)^{4}\cdot 10^{5.37}}}\approx 668.42\ R_{\odot }$

References[]

^ ^a ^b ^c ^d ^e ^f 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.
^ ^a ^b ^c ^d Arévalo, Aura (2019). The Red Supergiants in the Supermassive Stellar Cluster Westerlund 1 (Thesis). doi:10.11606/D.14.2019.tde-12092018-161841.
^ 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.
^ ^a ^b ^c 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. Gaia EDR3 record for this source at VizieR.
^ "Cl* Westerlund 1 W 75". Simbad.
^ Williams, D. R. (2013). "Sun Fact Sheet".
^ 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.
^ Andrews, H.; Fenech, D.; Prinja, R. K.; Clark, J. S.; Hindson, L. (2018). "Asymmetric ejecta of cool supergiants and hypergiants in the massive cluster Westerlund 1". Monthly Notices of the Royal Astronomical Society: Letters. 477 (1): L55–L59. arXiv:1803.07008. Bibcode:2018MNRAS.477L..55A. doi:10.1093/mnrasl/sly046. S2CID 53640431.

[radius-7] ${\sqrt {\left({\frac {5772}{3600}}\right)^{4}\cdot 10^{5.37}}}\approx 668.42\ R_{\odot }$

[:0-1] ^ ^a ^b ^c ^d ^e ^f 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.

[paulo2018-2] Arévalo, Aura (2019). The Red Supergiants in the Supermassive Stellar Cluster Westerlund 1 (Thesis). doi:10.11606/D.14.2019.tde-12092018-161841.

[clark-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.

[EDR3-4] 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. Gaia EDR3 record for this source at VizieR.

[5] "Cl* Westerlund 1 W 75". Simbad.

[6] Williams, D. R. (2013). "Sun Fact Sheet".

[8] 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.

[9] Andrews, H.; Fenech, D.; Prinja, R. K.; Clark, J. S.; Hindson, L. (2018). "Asymmetric ejecta of cool supergiants and hypergiants in the massive cluster Westerlund 1". Monthly Notices of the Royal Astronomical Society: Letters. 477 (1): L55–L59. arXiv:1803.07008. Bibcode:2018MNRAS.477L..55A. doi:10.1093/mnrasl/sly046. S2CID 53640431.

[1]

[2]

[3]

[4]

[5]

[6]

[a]

[7]

[8]

Westerlund 1-75

See also[]

Notes[]

References[]