NGC 4569

Messier 90 (NGC 4569) is a large spiral galaxy of type Sb in the constellation Virgo, approximately 60 million light-years away and one of the largest spiral members of the Virgo Cluster. Charles Messier discovered it on March 18, 1781. NGC 4569 is one of the relatively few Messier objects to exhibit a blueshift: its spectrum shows it moving toward us at roughly 250 kilometers per second relative to our own galaxy, despite being a member of the Virgo Cluster which is itself receding. This indicates M90 is currently falling back toward the center of the cluster after reaching the far side of its orbit, moving in our direction at high speed within the cluster's gravitational potential well.

NGC 4569 appears large on the sky and possesses a bright, slightly elongated core and extensive disk. Its relatively low mass-to-size ratio suggests it is a low-density galaxy for its angular size. The galaxy is undergoing significant ram-pressure stripping — hot intracluster gas is sweeping away M90's own interstellar gas as it plows through the Virgo Cluster at high velocity, gradually quenching its star formation from the outside in. A companion, the small high-surface-brightness spiral IC 3583, lies to the north and appears slightly distorted, leading Herbert Arp to include this system in his Atlas of Peculiar Galaxies. Both are visible in this image.

In a small telescope M90 appears as a moderately bright, elongated oval; larger apertures show a brighter elongated core and a hint of the disk. This CCD composite was made in April 1998 at the Kitt Peak National Observatory 0.9-meter telescope.