Messier 90 is a member of the Virgo Cluster, being one of its largest and brightest spiral galaxies, with an absolute magnitude of around -22. The galaxy is located approximately 1°.5 away from the subgroup centered on Messier 87. As a consequence of the galaxy's interaction with the intracluster medium in the Virgo Cluster, the galaxy has lost much of its interstellar medium. As a result of this process, which is referred to as ram-pressure stripping, the galaxy's interstellar medium and star formation regions appear severely truncated compared to similar galaxies outside the Virgo Cluster and there are even H II regions outside the galactic plane, as well as long tails of ionized gas that has been stripped of M90.
As stated above, the star formation in Messier 90 appears truncated. Consequently, the galaxy's spiral arms appear to be smooth and featureless, rather than knotted like galaxies with extended star formation., which justifies why this galaxy, along with NGC 4921 in the Coma Cluster has been classified as the prototype of an anemic galaxy. Some authors go even further and consider it is a passive spiral galaxy, similar to those found on galaxy clusters with high redshift. However, the center of Messier 90 appears to be a site of significant star formation activity, where around 5*104 stars of spectral types O and B that formed around 5 to 6 million years ago are surrounded by a large amount of A-type supergiants that were born in other starburst that took place before the former, between 15 and 30 million years ago. Multiple supernovae in the nucleus have produced 'superwinds' that are blowing the galaxy's interstellar medium outward into the intracluster medium collimated in two jets, one of which is being disturbed by interaction with Virgo's intracluster medium as the galaxy moves through it.
Blueshift
The spectrum of Messier 90 is blueshifted, which indicates that it is moving towards the Earth. In contrast, the spectra of most other galaxies are redshifted. The blueshift was originally used to argue that Messier 90 was actually an object in the foreground of the Virgo Cluster. However, since the phenomenon was limited mostly to galaxies in the same part of the sky as the Virgo Cluster, it appeared that this inference based on the blueshift was incorrect. Instead, the blueshift is thought to be evidence for the large range in velocities of objects within the Virgo Cluster itself.
