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NGC 1466

NGC 1466
Observation data (J2000 epoch)
ConstellationHydrus
Right ascension03h 44m 33s[1]
Declination−71° 40′ 17″[1]
Distance48.5 kpc (158 kly)[2]
Apparent magnitude (V)11.4[3]
Apparent dimensions (V)3.50′[1]
Physical characteristics
Mass1.4×105[4] M☉
Metallicity = −1.60[5] dex
Estimated age13.1[6] Gyr
Other designationsSL1, LW1, ESO54SC16, KMHK1,[1] PGC 2802621
See also: Globular cluster, List of globular clusters

NGC 1466 is the New General Catalogue designation for a globular cluster in the deep southern constellation of Hydrus. It is located in the outskirts of the Large Magellanic Cloud,[5] which is a satellite galaxy of the Milky Way. The object was discovered November 26, 1834 by English astronomer John Herschel.[7] John Dreyer described it as "pF, pS, iR, glbM, *7 f", meaning "pretty faint, pretty small, irregular round, gradually a little brighter middle, with a 7th magnitude star nearby".[8] When using a small telescope, this is a "faint, small, unresolved and difficult" target with an angular size of 1.9 arc minutes. It has an integrated visual magnitude of 11.4.[3]

This cluster has a reddening corrected distance modulus of 18.43±0.15,[5] corresponding to a distance of 48.5 kpc.[2] The cluster has a mass of about 140,000 times the mass of the Sun.[4] It is an old cluster, having an estimated age of 13.1 billion years.[5] In photographs, the cluster spans an apparent size of 3.50 arc minutes.[1] The core radius has an angular size of 10.7±0.4 arc seconds,[5] while the half-light radius is 24.3 arc seconds.[4]

There are a total of 49 known and one candidate RR Lyrae variable stars in the cluster, as of 2011. Eight are RRd, or double-mode RR Lyrae variables. The average periods are 0.591 days for RR Lyrae type ab and 0.335 days for RR Lyrae type c. These are consistent with a classification of Oosterhoff-intermediate for the cluster. Twelve other variables have been identified, including two long-period variables and a Cepheid variable.[5]

References

  1. ^ a b c d e Bica, E.; et al. (September 2008), "A general catalogue of extended objects in the Magellanic System", Monthly Notices of the Royal Astronomical Society, 389 (2): 678−690, arXiv:0806.3049, Bibcode:2008MNRAS.389..678B, doi:10.1111/j.1365-2966.2008.13612.x, S2CID 1867090.
  2. ^ a b The distance d in parsecs is given by:
    d = 10(m - M + 5)/5 = 104.686 = 48,528.9
    where m - M is the distance modulus. See:
    Webb, Stephen (1999), Measuring the Universe: The Cosmological Distance Ladder, Springer Science & Business Media, p. 76, ISBN 978-1852331061.
  3. ^ a b Inglis, Mike (2013), Observer's Guide to Star Clusters, The Patrick Moore Practical Astronomy Series, Springer Science & Business Media, p. 128, Bibcode:2013ogsc.book.....I, ISBN 978-1461475675.
  4. ^ a b c Noyola, E.; Gebhardt, K. (September 2007), "Surface Brightness Profiles for a Sample of LMC, SMC, and Fornax Galaxy Globular Clusters", The Astronomical Journal, 134 (3): 912−925, arXiv:0705.3464, Bibcode:2007AJ....134..912N, doi:10.1086/520061, S2CID 33640. See table 5.
  5. ^ a b c d e f Kuehn, Charles A.; et al. (October 2011), "Variable Stars in Large Magellanic Cloud Globular Clusters. I. NGC 1466", The Astronomical Journal, 142 (4): 14, arXiv:1107.5515, Bibcode:2011AJ....142..107K, doi:10.1088/0004-6256/142/4/107, S2CID 119199717, 107.
  6. ^ Santos, J. F. C. Jr.; Piatti, A. E. (December 2004), "Ages and metallicities of star clusters: New calibrations and diagnostic diagrams from visible integrated spectra", Astronomy and Astrophysics, 428: 79−88, arXiv:astro-ph/0409313, Bibcode:2004A&A...428...79S, doi:10.1051/0004-6361:20041560, S2CID 11068323.
  7. ^ Seligman, Courtney, "NGC Objects: NGC 1450 - 1499", Celestial Atlas, retrieved 2016-12-14.
  8. ^ Dreyer, J. L. E. (1888), "A New General Catalogue of Nebulæ and Clusters of Stars, being the Catalogue of the late Sir John F. W. Herschel, Bart, revised, corrected, and enlarged", Memoirs of the Royal Astronomical Society, 49: 1, Bibcode:1888MmRAS..49....1D
  • Media related to NGC 1466 at Wikimedia Commons
Quelle: https://en.wikipedia.org/wiki/NGC_1466