NGC 6522

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NGC 6522
NGC 6522 ACS 435 658 Wiki.jpg
Observation data (J2000 epoch)
Class VI[ citation needed ]
Constellation Sagittarius
Right ascension 18h 03m 34.08s [1]
Declination −30° 02′ 02.3″ [1]
Distance 25.1  kly (7.7  kpc) [2]
Apparent magnitude (V)8.3 [3]
Apparent dimensions (V)9.4′ [3]
Physical characteristics
Absolute magnitude −7.67 [1]
Mass5.93×104 [4]   M☉
Metallicity  = –1.34 [2] dex
Estimated age12.0  Gyr [5]
Other designationsGCl 82, C 1800-300 [6]
See also: Globular cluster, List of globular clusters

NGC 6522 is a globular cluster of stars in the southern constellation of Sagittarius. It was discovered by German-British astronomer William Herschel on June 24, 1784. The cluster has an apparent visual magnitude of 8.3 and an angular diameter of 9.4′. [3] It is located at a distance of 25.1  kly (7.7  kpc ) from the Sun, [2] and lies in the Milky Way's central bulge, [7] about 2.0 kly (0.6 kpc) from the Galactic Center. [1] The cluster is centered in a region of the sky known as Baade's Window. [8] It is highly impacted by reddening due to interstellar dust and the view is heavily contaminated by field stars, making it more difficult identify members. [9]

Contents

NGC 6522 is possibly the oldest star cluster in the Milky Way, [10] with an age of more than 12 billion years. [11] [12] It is a core collapsed cluster with a core radius of 0.5′ and a 1.0′ half-light radius. [9] The cluster formed four billion years before the Milky Way galactic bar appeared, and may have been confined to the bar for a period of time. At present it trails the bar in its orbit around the core. [13]

This is a low mass globular cluster with an estimated 5.93×104 times the mass of the Sun. Distinctive chemical abundances among the members indicate the cluster has multiple populations of stars, with the younger populations exhibiting pollution from earlier generations. [4] Twenty variable stars have been identified as members of NGC 6522, consisting of eight RR Lyrae, three type II Cepheids, and nine long-period variable stars. [9] Six pulsars have been discovered. [14]

Related Research Articles

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<span class="mw-page-title-main">Messier 19</span> Globular cluster in Ophiuchus

Messier 19 or M19 is a globular cluster in the constellation Ophiuchus. It was discovered by Charles Messier on June 5, 1764 and added to his catalogue of comet-like objects that same year. It was resolved into individual stars by William Herschel in 1784. His son, John Herschel, described it as "a superb cluster resolvable into countless stars". The cluster is located 4.5° WSW of Theta Ophiuchi and is just visible as a fuzzy point of light using 50 mm (2.0 in) binoculars. Using a telescope with a 25.4 cm (10.0 in) aperture, the cluster shows an oval appearance with a 3′ × 4′ core and a 5′ × 7′ halo.

<span class="mw-page-title-main">Messier 28</span> Globular cluster in the constellation of Sagittarius

Messier 28 or M28, also known as NGC 6626, is a globular cluster of stars in the center-west of Sagittarius. It was discovered by French astronomer Charles Messier in 1764. He briefly described it as a "nebula containing no star... round, seen with difficulty in 31⁄2-foot telescope; Diam 2′."

<span class="mw-page-title-main">Messier 56</span> Globular cluster in the constellation Lyra

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<span class="mw-page-title-main">Messier 62</span> Globular cluster in the constellation Ophiuchus

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<span class="mw-page-title-main">NGC 5986</span> Globular cluster in the constellation Lupus

NGC 5986 is a globular cluster of stars in the southern constellation of Lupus, located at a distance of approximately 34 kilolight-years from the Sun. It was discovered by Scottish astronomer James Dunlop on May 10, 1826. John L. E. Dreyer described it as, "a remarkable object, a globular cluster, very bright, large, round, very gradually brighter middle, stars of 13th to 15th magnitude". Its prograde–retrograde orbit through the Milky Way galaxy is considered irregular and highly eccentric. It has a mean heliocentric radial velocity of +100 km/s. The galacto-centric distance is 17 kly (5.2 kpc), which puts it in the galaxy's inner halo.

<span class="mw-page-title-main">NGC 1851</span> Globular cluster in the constellation Columba

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<span class="mw-page-title-main">NGC 1261</span> Globular cluster in the constellation Horologium

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<span class="mw-page-title-main">Palomar 6</span>

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<span class="mw-page-title-main">Terzan 5</span>

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<span class="mw-page-title-main">NGC 6496</span> Globular cluster in the constellation Scorpius

NGC 6496 is a globular cluster which is in the direction of the Milky Way's galactic bulge based on observations collected with the WFPC2 on board the Hubble Space Telescope. NGC 6496 was originally believed to be a member of the disc system of the Galactic Center, but scientists questioned this classification. It was instead suggested that NGC 6496, together with two other clusters, NGC 6624 and NGC 6637, could be halo clusters with strongly inclined orbits. NGC 6496 lies in the Southern sky at RA=17:59:03.68 and Dec=-44:15:57.4.

<span class="mw-page-title-main">NGC 6642</span> Globular cluster in the constellation Sagittarius

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<span class="mw-page-title-main">NGC 5286</span> Globular cluster in the constellation Centaurus

NGC 5286 is a globular cluster of stars located some 35,900 light years away in the constellation Centaurus. At this distance, the light from the cluster has undergone reddening from interstellar gas and dust equal to E(B – V) = 0.24 magnitude in the UBV photometric system. The cluster lies 4 arc-minutes north of the naked-eye star M Centauri. It was discovered by Scottish astronomer James Dunlop, active in Australia, and listed in his 1827 catalog.

<span class="mw-page-title-main">NGC 4372</span> Globular cluster in the constellation Musca

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<span class="mw-page-title-main">NGC 6388</span> Globular cluster in the constellation Scorpius

NGC 6388 is a globular cluster of stars located in the southern constellation of Scorpius. The cluster was discovered by Scottish astronomer James Dunlop on May 13, 1826 using a 20 cm (9 in) reflector telescope. It was later determined to be a globular cluster by English astronomer John Herschel, who was able to resolve it into individual stars. NGC 6388 is located at a distance of approximately 35,600 light-years (10.90 kpc) from the Sun. Due to its apparent visual magnitude of +6.8, binoculars or a small telescope are required to view it.

<span class="mw-page-title-main">NGC 6441</span> Globular cluster in Scorpius

NGC 6441, sometimes also known as the Silver Nugget Cluster, is a globular cluster in the southern constellation of Scorpius. It was discovered by the Scottish astronomer James Dunlop on May 13, 1826, who described it as "a small, well-defined rather bright nebula, about 20″ in diameter". The cluster is located 5 arc minutes east-northeast of the star G Scorpii, and is some 43,000 light-years from the Sun.

<span class="mw-page-title-main">NGC 6426</span> Globular cluster in the constellation Ophiuchus

NGC 6426 is a globular cluster of stars located in the equatorial constellation of Ophiuchus. It was discovered by the German-English astronomer William Herschel on 3 June 1786. This cluster is at a distance of 67,000 light years from the Sun. It has an apparent visual magnitude of 10.9 and an angular diameter of 4.2′, making it difficult to observe with a small telescope.

<span class="mw-page-title-main">NGC 6535</span> Globular cluster in the constellation Serpens

NGC 6535 is a globular cluster of stars located at a distance of 22,200 light years from Earth in the equatorial constellation of Serpens, and is listed in the New General Catalogue. Its discovery is usually attributed to astronomer John Russell Hind in 1852. However, Wolfgang Steinicke has uncovered evidence that William Herschel's first discovery was actually NGC 6535, which he observed on 24 August 1780.

References

  1. 1 2 3 4 Di Criscienzo, M.; et al. (February 2006). "RR Lyrae-based calibration of the Globular Cluster Luminosity Function". Monthly Notices of the Royal Astronomical Society. 365 (4): 1357–1366. arXiv: astro-ph/0511128 . Bibcode:2006MNRAS.365.1357D. doi: 10.1111/j.1365-2966.2005.09819.x . S2CID   17838243.
  2. 1 2 3 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.
  3. 1 2 3 O'Meara, Stephen James (2013). Deep-Sky Companions: Southern Gems. Cambridge University Press. p. 367. ISBN   9781107015012.
  4. 1 2 Fernández-Trincado, J. G.; et al. (July 2019). "H-band discovery of additional second-generation stars in the Galactic bulge globular cluster NGC 6522 as observed by APOGEE and Gaia". Astronomy & Astrophysics. 627. id. A178. arXiv: 1801.07136 . Bibcode:2019A&A...627A.178F. doi:10.1051/0004-6361/201834391.
  5. ↑ Koleva, M.; et al. (April 2008). "Spectroscopic ages and metallicities of stellar populations: validation of full spectrum fitting". Monthly Notices of the Royal Astronomical Society . 385 (4): 1998–2010. arXiv: 0801.0871 . Bibcode:2008MNRAS.385.1998K. doi: 10.1111/j.1365-2966.2008.12908.x . S2CID   17571531.
  6. ↑ "SIMBAD Astronomical Database". Results for NGC 6522. Retrieved 2011-03-13.
  7. ↑ Ness, Melissa; et al. (December 2014). "NGC 6522: a typical globular cluster in the Galactic bulge without signatures of rapidly rotating Population III stars". Monthly Notices of the Royal Astronomical Society. 445 (3): 2994−2998. arXiv: 1408.0290 . Bibcode:2014MNRAS.445.2994N. doi: 10.1093/mnras/stu2144 .
  8. ↑ "NGC 6522". Students for the Exploration and Development of Space. Retrieved 2020-09-23.
  9. 1 2 3 Arellano Ferro, A.; et al. (October 2023). "Variable stars in the field of the Galactic bulge globular cluster NGC 6522". Astrophysics and Space Science. 368 (10). id. 91. arXiv: 2310.16257 . Bibcode:2023Ap&SS.368...91A. doi:10.1007/s10509-023-04249-4.
  10. ↑ Barbuy, B.; et al. (November 2009). "VLT-FLAMES Analysis of 8 giants in the Bulge Metal-poor Globular Cluster NGC 6522: Oldest Cluster in the Galaxy?". Astronomy and Astrophysics. 507 (1): 405–415. arXiv: 0908.3603 . Bibcode:2009A&A...507..405B. doi:10.1051/0004-6361/200912748.
  11. ↑ Shiga, David (30 April 2011). "The universe's first stars were whirling dervishes". New Scientist : 20. Retrieved 2024-09-09.
  12. ↑ Chiappini, Cristina; et al. (28 April 2011). "Imprints of fast-rotating massive stars in the Galactic Bulge". Nature. 472 (7344): 454–457. Bibcode:2011Natur.472..454C. doi:10.1038/nature10000. PMID   21525928.
  13. ↑ Barbuy, B.; et al. (October 2021). "UVES analysis of red giants in the bulge globular cluster NGC 6522". Astronomy & Astrophysics. 654. id. A29. arXiv: 2107.08746 . Bibcode:2021A&A...654A..29B. doi:10.1051/0004-6361/202140815.
  14. ↑ Abbate, F.; et al. (December 2023). "A MeerKAT view of the pulsars in the globular cluster NGC 6522". Astronomy & Astrophysics. 680. id. A47. arXiv: 2310.03800 . Bibcode:2023A&A...680A..47A. doi:10.1051/0004-6361/202347725.
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