NGC 545

Lore & Background

NGC 545 was discovered by German-British astronomer William Herschel on October 1, 1785. It is a lenticular galaxy located in the constellation Cetus, about 250 million light-years away, with an estimated diameter of 180,000 light-years. The galaxy is a member of the Abell 194 galaxy cluster and forms a close pair with NGC 547, which lies 0.5 arcminutes away; the two share a common envelope, though no tidal features such as tails or bridges have been observed between them. A stellar bridge has been detected connecting the pair to NGC 541, located 4.5 arcminutes to the southwest, at a projected distance of about 100 kiloparsecs.

A weak radio source with radio jets has been associated with NGC 545; its short jet crosses the more prominent jet of NGC 547. Observations by the Hubble Space Telescope of the galaxy's center did not reveal dust or disk features. At the center is believed to exist a supermassive black hole with a mass estimated at about 600 million solar masses, based on the stellar tidal disruption rate. Observations by the Chandra X-Ray Observatory revealed sharp surface brightness edges on the northeastern part of the galaxy and an extended tail in the soft band, presumed to result from NGC 545's motion toward the cluster center, identified as the location of NGC 547.

Reader's Guide

NGC 545 is significant as a member of the Abell 194 galaxy cluster and for its inclusion in the Atlas of Peculiar Galaxies alongside NGC 547. Its close pairing with NGC 547, with which it shares a common envelope yet lacks tidal features, presents an interesting case of galaxy interaction without obvious disruption. The detection of a stellar bridge to NGC 541 further highlights its role in a small group within the cluster. The galaxy hosts a weak radio source with jets, one of which crosses the more prominent jet of NGC 547, indicating complex radio morphology. The absence of dust or disk features in its center, combined with the presence of a supermassive black hole of about 600 million solar masses, adds to its profile as a relatively undisturbed lenticular galaxy. X-ray observations showing sharp surface brightness edges and an extended tail suggest that NGC 545 is moving toward the cluster center, providing clues about its dynamical history within Abell 194.

Did You Know?

• NGC 545 was discovered by William Herschel on October 1, 1785.
• A supermassive black hole at its center is estimated to have a mass of about 600 million solar masses.
• A stellar bridge connects the NGC 545/547 pair to NGC 541.