NGC 1261 - Misplaced Pages

(Redirected from Caldwell 87) Globular cluster in the constellation Horologium

NGC 1261
NGC 1261 from Hubble Legacy Archive
Observation data (J2000.0 epoch)
Class	II
Constellation	Horologium
Right ascension	03 12 16.21
Declination	–55° 12′ 58.4″
Distance	53.5 kly (16.4 kpc)
Apparent magnitude (V)	8.63
Apparent dimensions (V)	12.9′
Physical characteristics
Absolute magnitude	−7.81
Mass	3.41×10 `M`_☉
Metallicity	${\begin{smallmatrix}\left\end{smallmatrix}}$ = −1.38±0.14 dex
Estimated age	10.24 Gyr
Other designations	GCL 5, ESO 155-SC11, Caldwell 87, Melotte 19
See also: Globular cluster, List of globular clusters

NGC 1261 (also known as Caldwell 87) is a globular cluster of stars in the southern constellation of Horologium, first discovered by Scottish astronomer James Dunlop in 1826. The cluster is located at a distance of 53 kilolight-years from the Sun, and 59 kilolight-years from the Galactic Center. It is about 10.24 billion years old with 341,000 times the mass of the Sun. The cluster does not display the normal indications of core collapse, but evidence suggests it may have instead passed through a post core-collapse bounce state within the past two billion years. The central luminosity density is 2.22 L_☉·pc, which is low for a globular cluster. Despite this, it has a Shapley–Sawyer Concentration Class of II, indicating a dense central concentration.

A total of 22 RR Lyrae variables have been discovered in this cluster, along with two long-period variables, three SX Phoenicis variables, and an eclipsing binary. It was determined to be an Oosterhoff type I cluster, based on the periods of fourteen of the RR Lyrae variables. 18 probable blue straggler candidates have been identified.

References

^ Shapley, Harlow; Sawyer, Helen B. (August 1927), "A Classification of Globular Clusters", Harvard College Observatory Bulletin, 849 (849): 11–14, Bibcode:1927BHarO.849...11S.
^ 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.
^ Paust, Nathaniel E. Q.; et al. (February 2010), "The ACS Survey of Galactic Globular Clusters. VIII. Effects of Environment on Globular Cluster Global Mass Functions", The Astronomical Journal, 139 (2): 476–491, Bibcode:2010AJ....139..476P, doi:10.1088/0004-6256/139/2/476, hdl:2152/34371, S2CID 120965440.
^ "NGC 1261". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2020-04-08.
^ Kravtsov, V.; et al. (June 2010), "Wide-field multi-color photometry of the Galactic globular cluster NGC 1261", Astronomy and Astrophysics, 516: 8, arXiv:1005.0007, Bibcode:2010A&A...516A..23K, doi:10.1051/0004-6361/200913449, S2CID 55542820, A23.
^ 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.
^ 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.
Simunovic, Mirko; et al. (November 2014), "The Blue Straggler Star Population in NGC 1261: Evidence for a Post-core-collapse Bounce State", The Astrophysical Journal Letters, 795 (1): 5, arXiv:1410.0693, Bibcode:2014ApJ...795L..10S, doi:10.1088/2041-8205/795/1/L10, S2CID 119294014, L10.
Salinas, R.; et al. (September 2016), "An AO-assisted Variability Study of Four Globular Clusters", The Astronomical Journal, 152 (3): 10, arXiv:1605.06517, Bibcode:2016AJ....152...55S, doi:10.3847/0004-6256/152/3/55, S2CID 119304354, 55.
Wehlau, A.; Demers, S. (May 1977), "NGC 1261 and the Oosterhoff type I systems", Astronomy and Astrophysics, 57: 251–256, Bibcode:1977A&A....57..251W.

External links

Media related to NGC 1261 at Wikimedia Commons
NGC 1261 on WikiSky: DSS2, SDSS, GALEX, IRAS, Hydrogen α, X-Ray, Astrophoto, Sky Map, Articles and images
SEDS
NASA data
Photometry paper
Globular Clusters Database

v t e Astronomical catalogs
NGC	NGC 1256 NGC 1257 NGC 1258 NGC 1259 NGC 1260 NGC 1261 NGC 1262 NGC 1263 NGC 1264 NGC 1265 NGC 1266
Caldwell	C78 C79 C80 C81 C82 C83 C84 C85 C86 C87 C88 C89 C90 C91 C92 C93 C94 C95 C96

v t e Caldwell catalogue
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Astronomical catalog List of NGC objects 1001–2000

New General Catalogue 1000 to 1499

Constellation of Horologium

Stars

Bayer	α β γ δ ζ η ι λ μ ν
Variable	R TW
HD	27631
Other	DENIS 0334-49 Gliese 146 GJ 1061

Exoplanets	HD 27631 b ι Horologii b

Star
clusters

NGC	1252 1261
Other	Arp-Madore 1

Galaxies

NGC	1249 1433 1448 1483 1493 1510 1512
Other	PKS 0226-559 SPT0418-47

Galaxy clusters	Horologium Supercluster