Stellar Clusters are very useful laboratories for empirically studying stellar evolution. ... All cluster stars are at the same distance . All cluster stars have the same physical age . ... CM diagram Young Cluster In this case we see the Main Sequence fully represented. The blue dots represent massive stars with short main sequence lifetimes. ... Thus, identifying the most massive star which is still on the main sequence is an effective means of determining the age of a stellar cluster. ...

... The measurements extend to a lower 1.5 GHz limit of 1.0 mJy and comprise a complete sample with 1.5-GHz flux density 2.5 S1.5 J/AuJPh/47/145 VLA Survey of Rich Clusters of Galaxies II (Slee+, 1994) J/AuJPh/49/977 VLA Survey of Rich Clusters of Galaxies III (Slee+, 1996) ================================================================================ A VLA Survey of Rich Clusters of Galaxies II. ... Note (3): An elliptical Gaussian was fitted to the source. ...

... Editor's choices for the most educational Astronomy Pictures of the Day about clusters of galaxies: . APOD: 2006 March 21 - The Coma Cluster of Galaxies . ... APOD: 2005 November 22 - A Galactic Collision in Cluster Abell 1185 . ... A prominent example occurs on the left of the above image of the rich cluster of galaxies Abell 1185. ... Recent observations of Abell 1185 have found unusual globular clusters of stars that appear to belong only to the galaxy cluster and not to any individual galaxy. ...