Credits: Jim Misti (Image Acquisition), Aldo Zanetti (Processing)
Astronomical and Imaging Data
| RA: | 21h 33m 27.02s |
| DEC: | -00° 49′ 23.7″ |
| MAG: | 6.47 |
| Diameter: | 16′ |
| Const: | Aqr |
| OTA | OGS 32″ RC |
| Focal Length | 6000 |
| Camera | SBIG STL-11000M |
| Site | Arizona, USA |
| Sky Quality | Bortle 2 |
Useful Informations
NGC 7089, better known as Messier 2 (M2), is a large, rich, and highly concentrated globular cluster located in the constellation Aquarius. At approximately 37,500 light-years away, it’s one of the most distant globular clusters known in the Milky Way, and its properties make it a key object for studying stellar evolution and dynamics in a very dense environment.
Key Physical Properties
- Structure: M2 is a remarkably compact and centrally concentrated globular cluster, classified as Shapley-Sawyer Concentration Class II. This indicates that its stars are extremely dense toward the core, which has undergone gravitational collapse. The immense stellar crowding in the center makes it one of the most densely populated stellar regions in the galaxy.
- Age and Metallicity: The cluster is an ancient stellar system, with an estimated age of about 13 billion years. This places it among the oldest known objects in the universe. Its stars are very metal-poor ([Fe/H]≈−1.65 dex), which is consistent with their formation in the early, metal-deficient universe.
- Mass and Luminosity: M2 is one of the more massive and luminous globular clusters, containing an estimated 150,000 stars. Its total mass is about 900,000 times that of the Sun, and it shines with a luminosity roughly 270,000 times greater.
Notable Features and Scientific Significance
The extreme density and age of M2 provide a unique laboratory for astronomical research.
- Blue Stragglers: The cluster contains a significant population of blue straggler stars, which appear younger and bluer than their coeval counterparts. Their presence is thought to be a direct result of stellar collisions and mass transfer in binary systems, both of which are common in the dense core of a collapsed cluster.
- Variable Stars: M2 is home to a rich variety of variable stars, including at least 40 RR Lyrae stars. These pulsating stars are crucial for determining the cluster’s distance and are used as standard candles to measure cosmic distances.
- Pulsars: Astronomers have also detected several pulsars (rapidly rotating neutron stars) within the cluster, which are the remnants of massive stars that have gone through supernova explosions.