Messier 72

Messier 72
M72 from Hubble Space Telescope; 3.44′ view
Observation data (J2000 epoch)
ClassIX
ConstellationAquarius
Right ascension20h 53m 27.70s
Declination–12° 32′ 14.3″
Distance54.57 ± 1.17 kly (16.73 ± 0.36 kpc)
Apparent magnitude (V)9.3
Apparent dimensions (V)6.6'
Physical characteristics
Mass1.68×105 M☉
Metallicity[Fe/H] = –1.48 ± 0.03 dex
Estimated age9.5 Gyr
Other designationsNGC 6981, GCl 118
See also: Globular cluster, List of globular clusters

Messier 72 (also known as M72 or NGC 6981) is a globular cluster in the south west of the southern constellation of Aquarius.

Observational history

M72 was discovered by astronomer Pierre Méchain on August 29, 1780. His countryman Charles Messier looked for it 36 days later, and included it in his catalog. Both opted for the then-dominant of the competing terms for such objects, considering it a faint nebula rather than a cluster. With a larger instrument, astronomer John Herschel called it a bright "cluster of stars of a round figure". Astronomer Harlow Shapley noted a similarity to Messier 4 and 12.

It is visible in a good night sky as a faint nebula in a telescope with a 6 cm (2.4 in) aperture.

Properties

Based upon a 2011 census of variable stars, the cluster is 54,500 light-years (16,700 pc) away from the Sun. It has an estimated combined mass of 168,000 solar masses (M☉), and is around 9.5 billion years old. There are 43 identified variable stars in the cluster.

Map showing location of M72

See also

References and footnotes

  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. 1 2 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. 1 2 3 4 Figuera Jaimes, R.; et al. (October 2011), Henney, W. J.; Torres-Peimbert, S. (eds.), "XIII Latin American Regional IAU Meeting: (item) The Globular Cluster NGC 6981: Variable stars population, physical parameters and astrometry", Revista Mexicana de Astronomía y Astrofísica, Serie de Conferencias, vol. 40, pp. 235–236, Bibcode:2011RMxAC..40..235F.
  4. ↑ "Messier 72". SEDS Messier Catalog. Archived from the original on 1 July 2022. Retrieved 30 April 2022.
  5. 1 2 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. 1 2 Sollima, A.; et al. (April 2008), "The correlation between blue straggler and binary fractions in the core of Galactic globular clusters", Astronomy and Astrophysics, 481 (3): 701–704, arXiv:0801.4511, Bibcode:2008A&A...481..701S, doi:10.1051/0004-6361:20079082, S2CID 3088769
  7. ↑ "NGC 6981". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2006-11-16.
  8. ↑ Garfinkle, Robert A. (1997), Star-Hopping: Your Visa to Viewing the Universe, Cambridge University Press, p. 266, ISBN 978-0521598897
  9. ↑ Burnham, Robert (1978), Burnham's Celestial Handbook: An Observer's Guide to the Universe Beyond the Solar System, Dover Books on Astronomy Series, vol. 1 (2nd ed.), Courier Dover Publications, pp. 188–189, ISBN 978-0486235677
  10. Luginbuhl, Christian B.; Skiff, Brian A. (1998), Observing Handbook and Catalogue of Deep-Sky Objects (2nd ed.), Cambridge University Press, p. 25, ISBN 978-0521625562