Credit: Aldo Zanetti
Astronomical and Imaging Data
| RA: | 21h 40m 22.12s |
| DEC: | -23° 10′ 47.5″ |
| MAG: | 7.19 |
| Diameter: | 12′ |
| Const: | Cap |
| OTA | ASA 500/1900 |
| Focal Length | 1900 |
| Camera | PlayerOne Poseidon M |
| Site | Central Italy |
| Sky Quality | Bortle 4 |
Useful Informations
NGC 7099, also known as Messier 30 (M30), is a densely-packed globular cluster in the constellation Capricornus. It’s a particularly significant object for astronomers because it has undergone a process known as core collapse, which has dramatically increased the density of stars at its center.
Core Collapse and Stellar Dynamics
M30 is a Class V globular cluster, but its core is exceptionally dense due to a core-collapse event. This is a final stage of evolution for some globular clusters where the stars at the center have become so tightly packed that the core’s gravitational pull continues to grow, drawing in more and more stars and creating a highly concentrated, very bright core.
This high stellar density in M30’s core leads to frequent stellar encounters and collisions, which in turn create a high number of exotic stellar objects. The cluster has passed through a dynamic process called core collapse and now has a concentration of mass at its core of about a million times the Sun’s mass per cubic parsec. This makes it one of the highest density regions in the Milky Way galaxy. Stars in such close proximity will experience a high rate of interactions that can create binary star systems, as well as a type of star called a blue straggler that is formed by mass transfer.
A process of mass segregation may have caused the central region to gain a greater proportion of higher mass stars, creating a color gradient with increasing blueness toward the middle of the cluster.
Physical and Chemical Properties
M30 is a very old cluster, with an estimated age of about 13 billion years. It’s located approximately 27,100 light-years from Earth and has a mass of about 160,000 times that of the Sun. It is metal-poor, meaning its stars have a low abundance of elements heavier than helium and hydrogen, a characteristic of stars that formed in the early universe.
M30 is also notable for its retrograde orbit through the inner galactic halo, which suggests it may not have formed with the Milky Way but was instead captured from a satellite galaxy in the distant past. This makes it an important “fossil” for studying the formation and history of our galaxy.