Distant Open Cluster M103 . ... AURA , NOAO , NSF Explanation: Bright blue stars highlight the open cluster known as M103 . ... In fact, a formerly blue star has recently evolved off the main sequence and is visible above as the red giant star near the cluster center. In general, yellow stars like our Sun are usually less bright and hence less prominent in open clusters than their massive blue cousins. ... NASA Web Site Statements, Warnings, and Disclaimers . NASA Official: Jay Norris. ...