Credit: Aldo Zanetti
Astronomical and Imaging Data
| RA: | 21h 01m 29.38s |
| DEC: | +16° 11′ 14.4″ |
| Mag: | 10.56 |
| Diameter: | 3.6′ |
| Const: | Del |
| OTA | RC 12″ |
| Focal Length | 2432 |
| Camera | PlayerOne Poseidon M |
| Site | Central Italy |
| Sky Quality | Bortle 4 |
Useful Informations
NGC 7006, also known as Caldwell 42, is a distant and very old globular cluster located in the constellation Delphinus. Its position in the outer halo of the Milky Way makes it a valuable subject for studying the galaxy’s formation and its system of stellar clusters.
Physical Properties and Location
NGC 7006 is located approximately 135,000 light-years from Earth, placing it well outside the main galactic disk and in the galactic halo. It is five times as distant as the Sun is from the galactic center. This extreme distance and its high-velocity, elongated orbit suggest it may not be a native resident of the Milky Way but could instead be the remnant of a dwarf galaxy that was captured and absorbed by our galaxy in the distant past.
The cluster is classified as a Class I globular cluster, indicating a very high central concentration of stars. Despite its distance, it has a significant mass of over 300,000 solar masses.
Stellar and Chemical Composition
Like other ancient globular clusters, NGC 7006 is metal-poor, with a low abundance of elements heavier than hydrogen and helium. Its age is estimated to be around 12 billion years, a typical age for the oldest stellar systems in the universe.
The cluster’s extreme distance makes it challenging to study, but observations have revealed the presence of a population of variable stars, including RR Lyrae stars. These pulsating stars are crucial for accurately measuring the cluster’s distance. The study of these variables and other stellar populations within NGC 7006 provides valuable data for models of stellar evolution and the formation of the galactic halo.