Credit: X-ray: NASA/CXC/ESO/P.Rosati et al.; Optical: ESO/VLT/P.Rosati et al.
Clusters of galaxies are the largest gravitationally bound structures and their distribution reveals the web that holds the entire Universe together. A fundamental question is to understand how soon clusters formed after the Big Bang. The image above shows a particularly important set of observations, an optical and X-ray image of a cluster of galaxies called RDCS 1252.9-2927. The X-ray image(from the Chandra X-ray Observatory) allows astronomers to measure the mass of the cluster, while the optical data (obtained from the European Southern Observatory's Very Large Telescope) tell astronomers how distant (or, equivalently, how old) the cluster is. These data show that this object is about 8.5 billion light years away, or that it was formed in the Universe's infancy. It's also surprisingly massive - more than 200 trillion times the mass of the sun, making it the most massive distant cluster ever observed. The cluster holds another surprise as well - even though it was formed so long ago, it contains a surprisingly large amount of complex elements (like silicon, sulfur and iron).
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Page Author: Dr. Michael F. Corcoran
Last modified Friday, 20-Apr-2012 15:23:12 EDT