Decorative print of an image taken by the Hubble Telescope. © NASA
Messier 106 or NGC 4258 is a spiral galaxy with dimensions of 18.6 × 7.2 and an apparent magnitude of 8.3 in the constellation Canes Venatici.
M106 is a galaxy classified as type Sbp in the Hubble sequence, where the p stands for peculiar. Some authors also classify it as SABbc, i.e. between a normal spiral and a barred spiral.
At a distance of about 24 million light years, the galaxy is located in the vicinity of several galaxy groups, of which it is listed as a member depending on the author, for example the Ursa Major Group, the Coma Sculptor Group, the Canes Venatici I Group or the Canes Venatici II Group.
The galaxy has a diameter of about 135,000 light years. The core of the galaxy is active and has been known as a radio source since the 1950s. In 1995, Brent Tully et al. described that the centre ejects a jet that is thought to be related to the massive central object of this galaxy discovered in the same year. This central object is thought to be a black hole with a mass of just under 40 million solar masses.
In its vicinity, astrophysicists observe an emission line spectrum that gives the galaxy's core its classification as a LINER type (Low Ionisation Nuclear Emission-line Region).
The two spiral arms are characterised by large numbers of young, massive stars shining in a bluish light. The galaxy is currently undergoing a so-called "starburst", in which the star formation rate is greatly increased.
M106 was discovered in July 1781 by Pierre Méchain.
