Credit: Aldo Zanetti
Astronomical and Imaging Data
| RA: | 17h 23m 34.93s |
| DEC: | -17° 48′ 46.9″ |
| MAG: | 8.25 |
| Diameter: | 10′ |
| Const: | Oph |
| OTA | RC 12″ |
| Focal Length | 2432 |
| Camera | PlayerOne Poseidon M |
| Site | Central Italy |
| Sky Quality | Bortle 4 |
Useful Informations
NGC 6356 is a globular cluster located in the constellation Ophiuchus. While not as famous as some of its neighbors, it is a scientifically significant object due to its properties, particularly its high metallicity for a globular cluster.
Key Physical Properties
- Distance and Location: NGC 6356 is located about 49,600 light-years away from Earth. It resides in the inner galactic halo, putting it in a crowded region of the sky near the galactic center. This makes observations challenging due to the high number of foreground and background stars.
- Structure: The cluster is quite dense and concentrated toward its center, a characteristic confirmed by its Shapley-Sawyer Concentration Class of II. This high concentration suggests a dynamically advanced state, with a high number of stellar interactions in its core.
- Age and Metallicity: NGC 6356 is a very old cluster, with an estimated age of over 12 billion years. However, its most notable feature is its relatively high metallicity ([Fe/H]≈−0.4 dex). This makes it one of the more metal-rich globular clusters in the Milky Way and sets it apart from the more typical metal-poor halo clusters. The high metallicity and its location near the galactic disk raise questions about its origin. It may have formed from a gas cloud that was already enriched by previous generations of stars, or it could be an immigrant from a disrupted dwarf galaxy.
Scientific Significance
The properties of NGC 6356 provide valuable insights into the formation and evolution of star clusters and the Milky Way itself.
- Chemical Abundances: The cluster’s high metallicity makes it a key target for studying stellar abundance patterns. Research has shown that, like other globular clusters, NGC 6356’s stars have chemical inhomogeneities, such as an overabundance of nitrogen and a depletion of carbon. These variations are a puzzle for astronomers and suggest that the cluster’s stars formed from gas that was polluted by material from a previous generation of stars.
- Stellar Populations: The presence of chemically distinct stellar subpopulations is a topic of active research in NGC 6356 and other metal-rich globular clusters. Studying these populations can help unravel the cluster’s formation history and the processes of self-enrichment.