What's Behind Stephan's Quintet?
Submitted by chandra on Tue, 2009-07-21 13:25Recently, we released a beautiful image of Stephan's Quintet, showing a group of galaxies and the effects of a galactic collision. In our caption we noted that NGC 7320, the blue galaxy near the bottom of the image, is not a member of the group but is located much closer to the Earth. This is because, as stated in the journal paper by Ewan O'Sullivan, NGC 7320 has a much lower redshift than the other galaxies, and a lower redshift means a smaller distance according to standard cosmology.