Credit: Jim Fordice
Astronomical and Imaging Data
| RA: | 06h 48m 59.41s |
| DEC: | -36° 00′ 19.1″ |
| MAG: | 9.29 |
| Diameter: | 5′ |
| Const: | Pup |
| OTA | Planewave CDK24 |
| Focal Length | 3962mm |
| Camera | QHY 600M |
| Site | Río Hurtado, Chile |
| Sky Quality | Bortle 1 |
Useful Informations
The globular cluster NGC 2298 is a spectacular, densely packed collection of thousands of stars. It’s located in the southern constellation of Puppis and was discovered by James Dunlop on May 30, 1826.
Physical Characteristics and Stellar Population
As a typical globular cluster, NGC 2298 is a very old astronomical object. Its estimated age is approximately 12.6 to 13.2 billion years old. The stars within it are held together by their mutual gravitational attraction.
- Distance: The cluster is located around ∼ 34.9 kilolight-years ( ∼ 10.7 kiloparsecs) from Earth. Another estimate places the distance at approximately 4.17 kiloparsecs ( ∼ 13.6 kilolight-years).
- Metallicity: It is classified as metal-poor, with a typical iron abundance ratio of [Fe/H] ≈ −1.76 dex. This low metal content is characteristic of older stellar populations that formed early in the universe before significant heavy elements were synthesized and dispersed.
- Stellar Populations: Studies of its color-magnitude diagram (CMD), especially using observations from telescopes like the Hubble Space Telescope (HST), reveal complex stellar populations.
- It contains a Blue Horizontal Branch (BHB) sequence.
- Researchers have identified very hot Horizontal Branch (HB) stars, some reaching temperatures up to ∼100,000 K. The characteristics of these hot HB stars suggest that some are helium-enhanced compared to the general BHB population.
- The cluster also hosts numerous Blue Straggler Stars (BSSs), which are main-sequence stars that appear younger than the rest of the cluster.
Dynamical State and Origin
NGC 2298 is considered a dynamically evolved cluster that is actively interacting with the Milky Way.
- Disruption and Tidal Tails: It is currently undergoing disruption by the Galactic tide. This tidal stripping process has resulted in the cluster trailing a long tidal tail of stars that stretch beyond its main body. The presence of these extra-tidal structures, including leading and trailing tails, is strong evidence of the cluster’s interaction with the Milky Way.
- Galactic Association: Due to its location and orbital properties, NGC 2298 is suspected to be a former member of the disputed Canis Major Dwarf galaxy, suggesting it was accreted by the Milky Way in the past. Its orbit is also noted as being highly eccentric and possibly retrograde.
- Class: The cluster is classified as a concentration class VI.
The discovery of multiple stellar populations and the evidence of tidal stripping make NGC 2298 a key object for studying the evolution and ultimate fate of globular clusters within the Milky Way’s gravitational field.