NGC 6540
| NGC 6540 | |
|---|---|
 Hubble Space Telescopeimage of NGC 6540 | |
| Observation data (J2000epoch) | |
| Constellation | Sagittarius |
| Right ascension | 18h06m08.60s[1] |
| Declination | −27° 45′ 55.0″[1] |
| Distance | 12.07 ± 0.98 kly (3.7 ± 0.3 kpc)[2] |
| Apparent magnitude(V) | 9.30[3] |
| Physical characteristics | |
| Absolute magnitude | −5.38[1] |
| Radius | 4.75′ × 4.75′[3] |
| Metallicity | = −1.20[1]dex |
| Other designations | C 1803-278,NGC6540,Cr364[4] |
![{\displaystyle {\begin{smallmatrix}\left[{\ce {Fe}}/{\ce {H}}\right]\end{smallmatrix}}}](https://wikimedia.org/api/rest_v1/media/math/render/svg/4c0821bd80891e071c08e7c7ee8e022baedf522c)
NGC 6540is aglobular clusterof stars in the southerconstellationSagittarius,positioned about 4.66° away from theGalactic Center.[5]It was discovered by German-British astronomerWilhelm Herschelon May 24, 1784, with an 18.7-inch mirror telescope, who described the cluster as "pretty faint, not large, crookedly extended, easily resolvable". It has anapparent visual magnitudeof 9.3[3]with anangular diameterof about 9.5 arcminutes.
The cluster is located at a distance of 12 kly (3.7 kpc) from the Sun,[2]and 14 kly (4.4 kpc) from the Galactic Center. It was originally thought to be anopen clusterbefore being designated a globular.[1]The cluster includes a peculiarX-ray sourceof uncertain type.[6]
References
[edit]- ^abcdeDi 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.S2CID17838243.
- ^abPérez-Villegas, A.; et al. (May 2018). "Orbits of Selected Globular Clusters in the Galactic Bulge".Publications of the Astronomical Society of Australia.35.id. e021.arXiv:1804.05781.Bibcode:2018PASA...35...21P.doi:10.1017/pasa.2018.16.
- ^abc"NGC 6540".Students for the Exploration and Development of Space.Retrieved15 January2016.
- ^"NGC 6540".SIMBAD.Centre de données astronomiques de Strasbourg.Retrieved7 January2017.
- ^Bica, E.; et al. (March 1994). "The globular cluster NGC 6540".Astronomy and Astrophysics.283:67–75.Bibcode:1994A&A...283...67B.
- ^Mereghetti, Sandro; et al. (August 2018). "EXTraS discovery of a peculiar flaring X-ray source in the Galactic globular cluster NGC 6540".Astronomy & Astrophysics.616.id. A36.arXiv:1805.08057.Bibcode:2018A&A...616A..36M.doi:10.1051/0004-6361/201833086.
External links
[edit]- NGC 6540
- Robert Burnham, Jr,Burnham's Celestial Handbook: An observer's guide to the universe beyond the solar system,vol 3, p. 1556
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