The M81 Group

The M81 Group
The Irr II starburst galaxy M82 (see also the chapter opening image) is in a nearby cluster of about
a dozen galaxies, including the spectacular spiral M81. Several of the galaxies in this cluster are
connected by streamers of hydrogen gas. (a) The three brightest galaxies in the cloud at visual
wavelengths. The inset on the left shows large volumes of hydrogen gas, in red, being ejected from
M82. (b) This radio image, created from data taken by the Very Large Array, shows the streamers of
hydrogen gas that connect the bright galaxies and also several dim ones, seen as regions of bright
orange here