spacetoday.net: Dark matter galaxy discovered

Posted: Mon, Feb 28, 2005, 7:49 AM ET (1249 GMT)
Dark matter galaxy image (Cardiff Univ.)

Astronomers reported last week that they have discovered a galaxy that they believed is composed almost entirely of invisible dark matter. Cardiff University astronomers found the galaxy, designated VIRGOHI21, at radio wavelengths using the Lovell Telescope. The radio telescope data revealed a large mass of ordinary hydrogen atoms weighing 100 million solar masses. However, the rate of rotation of the hydrogen derived from the radio observations implied the existence of 1,000 times more mass, which astronomers believe is in the form of invisible dark matter. Visible-light observations of the region showed no sign of any stars of other ordinary matter that might otherwise explain the observations.