Composition:
Population I Stars
Lifespan
100 million yearsNumber of stars
1,000 to 10,000Notes:
Open (or galactic) clusters are physically related groups of stars which formed together by are not massive enough to be held together by mutual gravitational attraction. They originate from large cosmic gas/dust clouds in the Milky Way, and continue to orbit the galaxy, in the disk. In many diffuse nebulae, clouds forming stars are visible in the infrared so that we can observe the formation of new young open star clusters at this moment.Example (on left): M44.
