Noun
open cluster (plural open clusters)
(astronomy) a more or less irregular star cluster containing tens to thousands of stars
Around 15 light-years in diameter, it is located 3700 light-years away from Earth, citation and has been dated to around 2.2 billion years old. citation NGC 2362 is a small, compact open cluster, 5200 light-years from Earth. Source: Internet
By studying their abundances in open cluster stars, variables such as age and chemical composition are fixed. Source: Internet
Because of their high density, close encounters between stars in an open cluster are common. Source: Internet
Berkeley 90 is a smaller open cluster, with a diameter of 5 arcminutes. Source: Internet
Collinder 421 is a particularly old open cluster at an age of approximately 1 billion years; it is of magnitude 10.1. 3100 light-years from Earth, more than 30 stars are visible in a diameter of 8 arcseconds. Source: Internet
Dolidze 11 is an open cluster 400 million years old, farthest away of the three at 3700 light-years. Source: Internet