NGC 6553

NGC 6553 is a globular cluster in the constellation Sagittarius. NGC 6553 has an apparent magnitude of about 8th magnitude with an apparent diameter of 8.2 arcminutes.^[2] Its Shapley–Sawyer Concentration Class is XI,^[2] meaning the star concentration is very loose even at the center; it has stars of magnitude 20 and dimmer. It is located just over a degree southeast of Messier 8, the Lagoon Nebula.

NGC 6553
The globular cluster NGC 6553 imaged by the Hubble Space Telescope
Observation data (J2000 epoch)
Class	V
Constellation	Sagittarius
Right ascension	18^h 09^m 15.68^s^[1]
Declination	−25° 54′ 27.9″^[1]
Distance	19.6 kly (6.01 kpc)^[1]
Apparent magnitude (V)	8.06^[2]
Physical characteristics
Radius	4.1' x 4.1'^[2]
Metallicity	${\displaystyle {\begin{smallmatrix}\left[{\ce {Fe}}/{\ce {H}}\right]\end{smallmatrix}}}$ = -0.18^[3] dex
Other designations	GCl 88, C 1806-259^[1]
See also: Globular cluster, List of globular clusters

Unlike common globular clusters, NGC 6553 is relatively metal-rich, and there is evidence of at least two periods of star formation.^[4] Due to a complex star-forming record, the stars in the cluster are differing in composition, most notably in concentrations of sodium and aluminium.^[5]

NGC 6553 is very similar in composition to NGC 6528, suggesting an origin in a similar environment.^[6]

References

1. "NGC 6553". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 8 January 2017.
2. "NGC 6553". Retrieved 8 January 2016.
3. "A Galactic Globular Clusters Database: NGC 6553". Retrieved 8 January 2017.
4. Tang, Baitian; Cohen, Roger E.; Geisler, Doug; Schiavon, Ricardo P.; Majewski, Steven R.; Villanova, Sandro; Carrera, Ricardo; Zamora, Olga; Garcia-Hernandez, D. A.; Shetrone, Matthew; Frinchaboy, Peter; Meza, Andres; Fernández-Trincado, J. G.; Muñoz, Ricardo R.; Lin, Chien-Cheng; Lane, Richard R.; Nitschelm, Christian; Pan, Kaike; Bizyaev, Dmitry; Oravetz, Daniel; Simmons, Audrey (2016), "Two groups of red giants with distinct chemical abundances in the bulge globular cluster NGC 6553 through the eyes of APOGEE", Monthly Notices of the Royal Astronomical Society, 465: 19–31, arXiv:1610.06763, doi:10.1093/mnras/stw2739
5. Muñoz, C.; Villanova, S.; Geisler, D.; Cortés, C. C.; Moni Bidin, C.; Cohen, R. E.; Saviane, I.; Dias, B.; Tang, B.; Mauro, F. (2019), "The vertical Na–O relation in the bulge globular cluster NGC 6553", Monthly Notices of the Royal Astronomical Society, 492 (3): 3742–3752, arXiv:1912.03742, doi:10.1093/mnras/stz3586
6. Muñoz, C.; Geisler, D.; Villanova, S.; Saviane, I.; Cortés, C. C.; Dias, B.; Cohen, R. E.; Mauro, F.; Moni Bidin, C. (2018), "Chemical analysis of NGC 6528: One of the most metal-rich bulge globular clusters", Astronomy & Astrophysics, 620: A96, arXiv:1809.04164, doi:10.1051/0004-6361/201833373, S2CID 119085692

External links

•   Media related to NGC 6553 at Wikimedia Commons
• NGC 6553