M90

Part of the vast and populous Virgo Cluster of galaxies, M90 lies in the central parts of the Cluster in the sky, just within Virgo's northern border with Coma Berenices. It is part of the Virgo A subcluster centred around the immense galaxy M87 or Virgo A, and lies approximately 59 million light years from the Milky Way.

M90 is a galaxy with some unusual characteristics. Unlike most spiral galaxies, whose arms show complex structure, those of M90 are almost entirely smooth and featureless. This effect is due to its interaction with the medium within the Virgo Cluster, which has left its arms stripped of star-forming material. M90 is far from lifeless, however: in its nucleus, within dark lanes of nebulous material, hot supergiants are being born, and the remnants of numerous supernovae can be detected.

Unlike most galaxies, M90 is not receding from the Milky Way, but is travelling towards our own Galaxy at speeds close to 400 km/s. This fact has led to suggestions that it may be in the process of being ejected from the main Virgo Cluster, or that it may in fact already have escaped from the gravitational effects of the main Cluster, and be travelling out into intergalactic space.

Like many larger galaxies, including the Milky Way, M90 is attended by a smaller companion galaxy. In this case the companion is a tattered galaxy of irregular form known as IC 3583.