www.astro.cf.ac.uk/groups/galaxies/latestnews.html
We know that galaxies are predominately made of dark matter. We only dete ct them because of the small fraction of their mass which is in the form of baryonic material (the stuff we are made of), this forms itself into stars and we detect the radiation from these stars. An important questi on is whether there are galaxies in the Universe that remian hidden from us because they are totally dark. This could be because they contain no baryonic material at all or because the baryonic material they do have has not formed into stars. One way of detecting the latter type of objec t is by using the 21cm line of atomic hydrogen (a galaxy with gas but no stars).
Cardiff University School of Physics and Astronomy, Cardiff University, 5, The Parade, Cardi ff,CF24 3YB. Telephone Number: +44 29 2087 4458 Fax Number: +44 29 2087 4056 Last modified on February 18 2005.
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