Dwarf Galaxies
Dwarf galaxies are much smaller and have much lower masses (1/100 to 1/10) than normal spiral galaxies. Their structure is amorphous, hence they are also called irregular galaxies. They are the left-behind of small density fluctuations present in the early universe. They experience episodes of strong star formation, followed by periods without any significant star formation. Dwarf ellptical galaxies are also found, primarily in galaxy clusters.
NGC 6822
Maksutov-Newton, Canon 1100Da,
10.7 hours
Only 1.6 million ly away from us, this dwarf galaxy contains less than one 10th of the mass of our Milky Way and is hence a very unconspicuous object in the sky. Also here, its lower position (-15° declination) necessitated the cropping of trees to observe it. When inspecting the image in the dark one can see purple-coloured structures in the northern part of the galaxy body, some of which appear as rather round rings. This is ionised gas, and the rings are so-called Strömgren Spheres (after the Danish astrophysicist Bengt Strömgren).
NGC 205 (M 110)
Maksutov-Newton, Canon 1100Da,
6.1 hours
Because of its relatively small distance of 2.5 million light years, this little elliptical satellite galaxy of M 31 exhibits some morphological features. Apart from its rather elliptical shape, a compact, bright nucleus is seen. Close inspection reveals three dark patches close to the nucleus, in directions toward 1 and 4 o'clock; these patches are large dust clouds.