This is what astronomers call a low surface brightness dwarf galaxy. These galaxies seem to have few luminous stars so they are hard to see unless they are close-by the Milky Way. There could be a lot of them in the universe, but they are undetectable except by their gravitational influences on more visible galaxies. Malin 1 is located near the Milky Way. Researchers at the University of Cardif have a program for studying these kinds of galaxies:
Certain types of galaxies have been overlooked in galaxy surveys because they are fainter than the night-time sky. These Low Surface Brightness (LSB) galaxies have fewer stars per unit volume than the more 'normal' galaxies, which results in the galaxy being dim and so difficult to detect.
One possible explanation why these galaxies have such LSB is that tidal interactions between galaxies play an important role in star formation. This means that a LSB galaxy may be an isolated galaxy in space. To test this theory we have obtained deep images of fields around the giant LSB galaxy Malin 1 using the Wide Field camera on the Isaac Newton Telescope.
We are now identifying possible companion galaxies to Malin 1 to within a distance of 2.5 Mpc. We then intend to use the multi-object spectrograph (AUTOFIB) on the William Herschel Telescope to obtain redshifts of the possible companion galaxies we have identified. This will enable us to determine if Malin 1 is an isolated galaxy in space.
Copyright 1997 Dr. Sten Odenwald
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