Globular clusters rotate at heart Astronomers from the University of Texas at Austin and Germanys Max Planck Institute for Extraterrestrial Physics (MPE) recently found a surprise when studying some of the oldest star clusters in our galaxy. The stars at the centers of these clusters are rotating around a common axis. It was previously thought any central rotation would have been long erased, leaving the central stars to random orbits. The work has been accepted for publication in the Astrophysical Journal Letters. These globular clusters are ancient collections of up to a million old stars with simple chemical compositions, tightly bound together by gravity. Globular clusters orbit most galaxies, including our own Milky Way. Due to these clusters old age and fairly spherical shape, with a strong concentration of stars towards the center, they have historically been viewed as simple systems. However, new observations keep revealing surprising results. The team, led by MPEs Maximilian Fabricius and including Texas Eva Noyola, observed 11 globular clusters from the University of Texas at Austins McDonald Observatory with the Harlan J. Smith Telescope. They found that all of the clusters show this central rotation. This result is astonishing, Fabricius says. We did not expect this; originally we observed these globular clusters to measure their central velocity dispersions—that is, the random motions of stars within a cluster.
Posted on: Sun, 11 May 2014 11:55:35 +0000
Trending Topics
Recently Viewed Topics
© 2015