Astronomy:NGC 6553
| NGC 6553 | |
|---|---|
 The globular cluster NGC 6553 imaged by the Hubble Space Telescope | |
| Observation data (J2000 epoch) | |
| Class | V |
| Constellation | Sagittarius |
| Right ascension | 18h 09m 15.68s[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 | [math]\displaystyle{ \begin{smallmatrix}\left[\ce{Fe}/\ce{H}\right]\end{smallmatrix} }[/math] = -0.18[3] dex |
| Other designations | GCl 88, C 1806-259[1] |
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.
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
- ↑ 1.0 1.1 1.2 1.3 "NGC 6553". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=NGC+6553.
- ↑ 2.0 2.1 2.2 2.3 "NGC 6553". http://spider.seds.org/spider/MWGC/n6553.html.
- ↑ "A Galactic Globular Clusters Database: NGC 6553". http://gclusters.altervista.org/cluster_4.php?ggc=NGC+6553.
- ↑ Tang, Baitian; Cohen, Roger E.; Geisler, Doug; Schiavon, Ricardo P.; Majewski, Steven R.; Villanova, Sandro; Carrera, Ricardo; Zamora, Olga et al. (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, doi:10.1093/mnras/stw2739
- ↑ Muñoz, C.; Villanova, S.; Geisler, D.; Cortés, C. C.; Moni Bidin, C.; Cohen, R. E.; Saviane, I.; Dias, B. et al. (2019), "The vertical Na–O relation in the bulge globular cluster NGC 6553", Monthly Notices of the Royal Astronomical Society 492 (3): 3742–3752, doi:10.1093/mnras/stz3586
- ↑ Muñoz, C.; Geisler, D.; Villanova, S.; Saviane, I.; Cortés, C. C.; Dias, B.; Cohen, R. E.; Mauro, F. et al. (2018), "Chemical analysis of NGC 6528: One of the most metal-rich bulge globular clusters", Astronomy & Astrophysics 620: A96, doi:10.1051/0004-6361/201833373
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