Credit: Aldo Zanetti
Astronomical and Imaging Data
| RA: | 16h 46m 58.79s |
| DEC: | +47° 31′ 39.9″ |
| Mag: | 9.39 |
| Diameter: | 4.5′ |
| Const: | Her |
| OTA | RC 12″ |
| Focal Length | 2432 |
| Camera | PlayerOne Poseidon M |
| Site | Central Italy |
| Sky Quality | Bortle 4 |
Useful Informations
NGC 6229 is a faint, distant globular cluster located in the constellation Hercules, approximately 100,000 light-years from the Sun. Its remote location in the outer galactic halo makes it a valuable target for studying the properties of the oldest stellar populations and the overall structure of the Milky Way’s halo.
Key Physical Properties
- Age and Metallicity: NGC 6229 is an ancient stellar system with an estimated age of over 12 billion years. Its stars are metal-poor ([Fe/H]≈−1.47 dex), though not as extremely metal-poor as some other halo clusters. This suggests it formed early in the galaxy’s history from gas that had already undergone some level of enrichment by previous generations of stars.
- Stellar Populations: The cluster shows evidence of hosting two distinct stellar populations with different chemical compositions, a characteristic observed in a number of other globular clusters. This complexity provides clues about its formation and evolutionary history, possibly suggesting it may be the remnant core of a smaller dwarf galaxy that was accreted by the Milky Way.
- Structure: NGC 6229 is classified as a Shapley-Sawyer Concentration Class VII, which indicates a moderate degree of central concentration. Its core is quite dense, but it lacks the extreme stellar packing seen in core-collapsed clusters.
- Variable Stars: The cluster contains a population of variable stars, including RR Lyrae stars and Population II Cepheids, which are crucial for determining the cluster’s distance and for understanding stellar pulsation theory.