The biggest and closest “super” star cluster to Earth, has been captured in a new image released by NASA’s Chandra X-ray Observatory. This dense site in our Milky Way galaxy is where young massive stars have formed at a prodigious rate. The image combines deep Chandra data with previously released data from NASA’s Hubble Space Telescope. The X-rays detected by Chandra reveal young stars (mostly represented as white and pink) as well as diffuse heated gas throughout the cluster (colored pink, green, and blue, in order of increasing temperatures for the gas) . Westerlund contains more than 10,000 times the mass of the Sun and is between 3 million and 5 million years old. It’s an excellent target for studying star and planet formation processes, as well as the evolution of stars across a broad range of masses Fascinating, isn’t it?
How do star clusters form?
Open Clusters (Galactic Clusters):
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- These clusters contain a few hundred to a few thousand stars.
- They form in the plane of the Milky Way galaxy.
- Young open clusters are associated with regions of active star formation.
- Gravity pulls together gas and dust, leading to the birth of new stars.
- Over time, some stars are ejected due to gravitational interactions.
- Examples: Pleiades (M45), Hyades.
- Globular Clusters:
- These are dense, spherical clusters containing hundreds of thousands to millions of stars.
- They are found in the galactic halo (outside the galactic disk).
- Globular clusters are ancient, typically over 10 billion years old.
- Their stars are tightly bound due to strong gravitational forces.
- They likely formed early in the galaxy’s history.
- Examples: Omega Centauri (NGC 5139), M13 (Hercules Cluster).
- Formation Process:
- A molecular cloud (dense region of gas and dust) collapses under gravity.
- As the cloud contracts, it fragments into clumps.
- Each clump becomes a protostar, surrounded by a rotating disk.
- Protostars continue accreting material from the disk.
- Eventually, nuclear fusion ignites, and the protostar becomes a main-sequence star.
- Clusters form from these groups of stars born in the same molecular cloud.
