Credit: Aldo Zanetti
Astronomical and Imaging Data
| RA: | 14h 05m 27.29s |
| DEC: | +28° 32′ 04.0″ |
| MAG: | 9.04 |
| Diameter: | 9′ |
| Const: | Boo |
| OTA | RC 12″ |
| Focal Length | 2432 |
| Camera | PlayerOne Poseidon M |
| Site | Central Italy |
| Sky Quality | Bortle 4 |
Useful Informations
NGC 5466 is an ancient, sparse globular cluster located in the constellation Boötes, approximately 52,000 light-years from Earth. Its low stellar density and high galactic latitude make it a fascinating subject for studying stellar and galactic dynamics.
Key Physical Properties
- Loose Structure: Unlike more concentrated globular clusters like M13, NGC 5466 has a low central density. It belongs to Shapley-Sawyer Concentration Class XII, which is the least dense classification. This suggests it is a dynamically young cluster that has not yet reached a state of full gravitational collapse.
- Stellar Population: Despite its sparse appearance, the cluster is home to a variety of stellar populations, including numerous blue straggler stars and variable stars like RR Lyrae and SX Phoenicis. The high number of blue stragglers, which are thought to be formed from stellar collisions or binary star mergers, is particularly interesting given the cluster’s low density.
- Metallicity and Age: With a low metallicity ([Fe/H]≈−1.95 dex), NGC 5466 is an ancient object, with an estimated age of about 12.15 billion years. Its stars are exceptionally old and metal-poor, as is characteristic of globular clusters formed in the early universe.
Galactic Interaction and Tidal Stream
NGC 5466 is a prime example of a cluster interacting with the Milky Way’s gravitational field.
- Tidal Stream: It is the progenitor of a long, faint tidal stream that extends for tens of thousands of light-years across the sky. This stream is composed of stars that have been gravitationally stripped from the cluster as it orbits the Milky Way.
- Dynamical Significance: The discovery and study of this tidal stream, which has been traced across a large section of the sky, provide a unique test case for models of the Milky Way’s gravitational potential, particularly its elusive dark matter halo. By analyzing the path of the stream, astronomers can infer the distribution and shape of the dark matter that influences its orbit.