NGC 6541

NGC 6541
NGC 6541, imaged by the Hubble Space Telescope
Observation data (J2000 epoch)
ClassIII[1]
ConstellationCorona Australis
Right ascension18h 08m 02.36s[2]
Declination–43° 42′ 53.6″[2]
Distance24.8 ± 0.3 kly (7.6 ± 0.1 kpc)[3]
Apparent magnitude (V)6.3[4]
Apparent dimensions (V)15′[4]
Physical characteristics
Mass5.72×105[5] M☉
Metallicity = –1.53[6] dex
Estimated age12.93 Gyr[6]
Other designationsNGC 6541, Caldwell 78[7]
See also: Globular cluster, List of globular clusters

NGC 6541 (also known as Caldwell 78) is a globular cluster of stars in the southern constellation of Corona Australis. The globular cluster was discovered by Niccolò Cacciatore at the Palermo Astronomical Observatory, Sicily, on March 19, 1826. It was independently found by James Dunlop on July 3, 1826. The cluster has an apparent visual magnitude of 6.3 and an angular diameter of 15′. It is visible with binoculars or a small telescope.[4]

Located at a distance of 24.8 kly (7.6 kpc) from the Sun,[3] it is orbiting within the central region of the Milky Way about 7.2 kly (2.2 kpc) from the Galactic Center.[8] It is considered a metal-poor inner halo cluster, being the third most metal-poor globular cluster within 9.8 kly (3 kpc) of the center.[8] The cluster has 5.72×105 times the mass of the Sun.[5] It is estimated to be around 12.9 billion years old,[6] and is believed to have undergone core collapse.[8] A total of 94 blue straggler members have been identified,[9] as well as three W Ursae Majoris and nine SX Phoenicis variables.[10]

References

  1. ^ Shapley, Harlow; Sawyer, Helen B. (August 1927), "A Classification of Globular Clusters", Harvard College Observatory Bulletin, 849 (849): 11–14, Bibcode:1927BHarO.849...11S.
  2. ^ a b Goldsbury, Ryan; et al. (December 2010), "The ACS Survey of Galactic Globular Clusters. X. New Determinations of Centers for 65 Clusters", The Astronomical Journal, 140 (6): 1830–1837, arXiv:1008.2755, Bibcode:2010AJ....140.1830G, doi:10.1088/0004-6256/140/6/1830, S2CID 119183070.
  3. ^ a b Baumgardt, H.; Vasiliev, E. (August 2021), "Accurate distances to Galactic globular clusters through a combination of Gaia EDR3, HST, and literature data", Monthly Notices of the Royal Astronomical Society, 505 (4): 5957–5977, arXiv:2105.09526, Bibcode:2021MNRAS.505.5957B, doi:10.1093/mnras/stab1474.
  4. ^ a b c O'Meara, Stephen James (2011), Deep-Sky Companions: The Secret Deep, Cambridge, United Kingdom: Cambridge University Press, pp. 322, 375–377, ISBN 978-0521198769.
  5. ^ a b Boyles, J.; et al. (November 2011), "Young Radio Pulsars in Galactic Globular Clusters", The Astrophysical Journal, 742 (1): 51, arXiv:1108.4402, Bibcode:2011ApJ...742...51B, doi:10.1088/0004-637X/742/1/51, S2CID 118649860.
  6. ^ a b c Forbes, Duncan A.; Bridges, Terry (May 2010), "Accreted versus in situ Milky Way globular clusters", Monthly Notices of the Royal Astronomical Society, 404 (3): 1203–1214, arXiv:1001.4289, Bibcode:2010MNRAS.404.1203F, doi:10.1111/j.1365-2966.2010.16373.x, S2CID 51825384.
  7. ^ "NGC 6541". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2024-09-16.
  8. ^ a b c Lee, Jae-Woo; Carney, Bruce W. (November 2006), "VI Photometry of Globular Clusters NGC 6293 and NGC 6541: The Formation of the Metal-poor Inner Halo Globular Clusters", The Astronomical Journal, 132 (5): 2171–2186, arXiv:astro-ph/0606711, Bibcode:2006AJ....132.2171L, doi:10.1086/507412.
  9. ^ Raso, S.; et al. (2017), "The "UV-route" to Search for Blue Straggler Stars in Globular Clusters: First Results from theHSTUV Legacy Survey", The Astrophysical Journal, 839 (1): 64, arXiv:1704.01453, Bibcode:2017ApJ...839...64R, doi:10.3847/1538-4357/aa6891, S2CID 118939669.
  10. ^ Fiorentino, G.; et al. (March 2014), "Blue Straggler Masses from Pulsation Properties. I. The Case of NGC 6541", The Astrophysical Journal, 783 (1), id. 34, arXiv:1312.0388, Bibcode:2014ApJ...783...34F, doi:10.1088/0004-637X/783/1/34.