Penn State University astronomers have determined that 80 of the stars in this photo are members of the long-known but underappreciated star cluster Ruprecht 147. In this image, the brightest of these stars are circled in green, and the less-bright ones are circled in red. These stars were born out of the same cloud of gas and dust approximately two-billion years ago, and now are traveling together through space, bound by the force gravity. The astronomers have identified this cluster as a potentially important new reference gauge for fundamental stellar astrophysics. http://science.psu.edu/news-and-events/2012-news/Wright6-2012
Image by Chris Beckett and Stefano Meneguolo, Royal Astronomical Society of Canada. Annotations by Jason Curtis, Penn State University.