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 08.92s
Declination	−45° 49′ 58.5″
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
Parallax (π)	0.0893 ± 0.1477 mas
Distance	4,120 660; −330 pc
Details
Radius	722±36 R☉
Luminosity	120,000±14,000 L☉
Temperature	3,600 - 4,000 K
Other designations
	Westerlund 1 BKS E, 2MASS J16470892-4549585, Gaia DR3 8630199877892579584
Database references
SIMBAD	data

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^[6] (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.

The star is classified as a luminous cool supergiant emitting most of its energy in the infrared spectrum.^[7] It occupies the upper right corner of the Hertzsprung-Russell diagram. Using the effective temperature of 3,600 K,^[6] the bolometric luminosity of 68,000 L_☉^[6] and the solar effective temperature of 5,772 K,^[8] the radius of Westerlund 1-75 can be calculated using the Stefan-Boltzmann law at 668 R_☉.^[a]

Like Westerlund 1-20, Westerlund 1 W26 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.^[9]

Westerlund 1-75 is surrounded by extended nebula, although it appears less massive than nebulae around typical red supergiant stars.^[10]

Notes

^ ${\sqrt {\left({\frac {5772}{3600}}\right)^{4}\cdot 10^{4.83}}}\approx 668.42\ R_{\odot }$

References

^ ^a ^b ^c ^d ^e ^f Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy and Astrophysics. 674: A1. arXiv:2208.00211. Bibcode:2023A&A...674A...1G. doi:10.1051/0004-6361/202243940. S2CID 244398875. Gaia DR3 record for this source at VizieR.
^ ^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 Cutri, Roc M.; et al. (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.
^ Beasor, Emma R.; Davies, Ben; Smith, Nathan; Gehrz, Robert D.; Figer, Donald F. (2021). "The Age of Westerlund 1 Revisited". The Astrophysical Journal. 912 (1): 16. arXiv:2103.02609. Bibcode:2021ApJ...912...16B. doi:10.3847/1538-4357/abec44. S2CID 232110879.
^ ^a ^b ^c ^d 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.
^ "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-9] ${\sqrt {\left({\frac {5772}{3600}}\right)^{4}\cdot 10^{4.83}}}\approx 668.42\ R_{\odot }$

[DR3-1] ^ ^a ^b ^c ^d ^e ^f Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy and Astrophysics. 674: A1. arXiv:2208.00211. Bibcode:2023A&A...674A...1G. doi:10.1051/0004-6361/202243940. S2CID 244398875. Gaia DR3 record for this source at VizieR.

[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.

[2mass-4] Cutri, Roc M.; et al. (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.

[beasor2021-5] Beasor, Emma R.; Davies, Ben; Smith, Nathan; Gehrz, Robert D.; Figer, Donald F. (2021). "The Age of Westerlund 1 Revisited". The Astrophysical Journal. 912 (1): 16. arXiv:2103.02609. Bibcode:2021ApJ...912...16B. doi:10.3847/1538-4357/abec44. S2CID 232110879.

[:0-6] 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.

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

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

[10] 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.

[11] 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.

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Observation data Epoch J2000 Equinox J2000
Westerlund 1 super star cluster. The location of Wd 1-75 is circled. Credit: ESO
Constellation	Ara
Right ascension	16^h 47^m 08.92^s^[1]
Declination	−45° 49′ 58.5″^[1]
Apparent magnitude (V)	16.7
Characteristics
Evolutionary stage	Red supergiant
Spectral type	M1^[2] - M4Ia^[3]
Apparent magnitude (J)	6.933^[4]
Apparent magnitude (H)	4.673^[4]
Apparent magnitude (K)	3.28^[4]
Astrometry

Radial velocity (R_v)	−50.6±2.9^[1] km/s
Proper motion (μ)	RA: −2.029^[1] mas/yr Dec.: −4.248^[1] mas/yr
Parallax (π)	0.0893 ± 0.1477 mas^[1]
Distance	4,120 660 −330^[5] pc

Details

Radius	722±36^[2] `R`_☉
Luminosity	120,000±14,000^[2] `L`_☉
Temperature	3,600^[6] - 4,000^[2] K

Other designations
Westerlund 1 BKS E, 2MASS J16470892-4549585, Gaia DR3 8630199877892579584
Database references
SIMBAD	data

See also

Notes

References