| NGC 6440 | |
|---|---|
 HST image of NGC 6440 | |
| Observation data (J2000 epoch) | |
| Class | V |
| Constellation | Sagittarius |
| Right ascension | 17 48 52.67 |
| Declination | −20° 21′ 34.5″ |
| Distance | 27.1 ± 1.3 kly (8.3 ± 0.4 kpc) |
| Apparent magnitude (V) | 9.3 |
| Apparent dimensions (V) | 4.4′ |
| Physical characteristics | |
| Mass | > 4.42×10 M☉ |
| Metallicity | = −0.56 dex |
| Estimated age | ≈11 Gyr |
| Other designations | NGC 6440 |
| See also: Globular cluster, List of globular clusters | |
= −0.56 NGC 6440 is a globular cluster of stars in the southern constellation of Sagittarius. It was discovered by German-English astronomer William Herschel on 28 May 1786. With an apparent visual magnitude of 9.3 and an angular diameter of 4.4′, it can be observed as a fuzzy blob when viewed through a small telescope. Its Shapley–Sawyer Concentration Class is V.
This cluster is located at a distance of 27.1 ± 1.3 kly (8.3 ± 0.4 kpc) from the Sun. It is situated toward the galactic bulge of the Milky Way, about 26 kly (8.0 kpc) from the Galactic Center. The center of the cluster is fairly concentrated, but does not appear to have undergone a core collapse. It has a core radius of 0.85 ly (0.26 pc), and a half-mass radius of 6.6 ly (2.02 pc). Observations suggest it is one of the most metal–rich globular clusters in the galaxy, and it is close to solar metallicity. NGC 6440 is a rich target for Astrophysical X-ray sources. As of 2022, thirteen pulsars have been discovered in NGC 6440.
References
- ^ Shapley, Harlow; Sawyer, Helen B. (August 1927). "A Classification of Globular Clusters". Harvard College Observatory Bulletin. 849: 11–14. Bibcode:1927BHarO.849...11S.
- ^ 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.
- ^ Vleeschower, L.; et al. (June 2022). "Discoveries and timing of pulsars in NGC 6440". Monthly Notices of the Royal Astronomical Society. 513 (1): 1386–1399. arXiv:2204.00086. Bibcode:2022MNRAS.513.1386V. doi:10.1093/mnras/stac921.
- ^ O'Meara, Stephen James (2007). Herschel 400 Observing Guide. Cambridge University Press. p. 233. ISBN 9780521858939.
- Origlia, L.; et al. (November 2008). "Probing the Galactic Bulge with Deep Adaptive Optics Imaging: The Age of NGC 6440". The Astrophysical Journal Letters. 687 (2): L79 – L82. arXiv:0809.3939. Bibcode:2008ApJ...687L..79O. doi:10.1086/593351.
- "NGC 6440". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 8 January 2017.
- Ortolani, S.; et al. (December 1994). "The low galactic latitude metal-rich globular cluster NGC 6440". Astronomy and Astrophysics Supplement. 108: 653–659. Bibcode:1994A&AS..108..653O.
External links
Media related to NGC 6440 at Wikimedia Commons- "Star-studded cluster (NGC 6440 NIRCam wide-field image)". ESA. Retrieved 2024-08-20.
- Frommert, Hartmut. "NGC 6440". Students for the Exploration and Development of Space. Retrieved 19 December 2019.
