Credits: Jim Misti (Image Acquisition), Aldo Zanetti (Processing)
Astronomical and Imaging Data
| RA: | 15h 18m 33.22s |
| DEC: | +02° 04′ 51.7″ |
| MAG: | 5.65 |
| Diameter: | 21.6′ |
| Const: | Ser |
| OTA | OGS 32″ RC |
| Focal Length | 6000 |
| Camera | SBIG STL-11000M |
| Site | Arizona, USA |
| Sky Quality | Bortle 2 |
Useful Informations
NGC 5904, more commonly known as Messier 5 (M5), is a large and densely populated globular cluster located in the constellation Serpens. It’s one of the oldest and most massive globular clusters in the Milky Way, making it a prime target for studying stellar evolution and the dynamics of dense stellar systems.
Physical and Chemical Properties
M5 is situated about 24,500 light-years from Earth and is home to over 100,000 stars, with estimates as high as 500,000. It’s classified as a Shapley-Sawyer Concentration Class V, indicating a moderate level of central concentration, though it’s still quite dense. The cluster’s immense size, with a diameter of roughly 165 light-years, is notable.
- Age and Metallicity: The cluster is a very ancient stellar system, with an estimated age of 13 billion years, which places it among the oldest known objects in the galaxy. Its stars are metal-poor ([Fe/H]≈−1.3 dex), meaning they have a low abundance of elements heavier than hydrogen and helium. This is consistent with its formation from the pristine gas of the early universe.
Notable Stellar Content and Scientific Significance
M5 is a key object for understanding stellar evolution and stellar populations.
- Variable Stars: The cluster is famous for its rich population of variable stars, particularly RR Lyrae stars. Over 100 of these pulsating stars have been identified in M5, making it an excellent laboratory for studying stellar pulsation and for calibrating the cosmic distance scale.
- Blue Stragglers: It also contains a significant number of blue straggler stars, which are stars that appear younger and bluer than their coeval counterparts. The presence of these stars is a strong indicator of stellar collisions or mergers in the dense stellar environment of the cluster’s core.
- Dynamical Evolution: The cluster’s size and mass provide a unique opportunity to study the long-term dynamical evolution of globular clusters, including processes like core collapse and mass segregation, where heavier stars sink toward the center.