NGC 4902 Group

Lore & Background

The NGC 4902 Group is centered on the barred spiral galaxy NGC 4902, which lies about 110 million light years away in the constellation Virgo. Other members of the group include NGC 4887, NGC 4897, and NGC 4899. NGC 4899 lies 34 arcminutes north of NGC 4902, and NGC 4897 lies 64 arcminutes north.

The group belongs to the same galaxy cloud as NGC 5054 and is part of the Virgo Supercluster, located within the Virgo II Groups or Virgo Southern Extension. Its size is described as similar to that of the Local Group.

NGC 4902 itself has a prominent bar, overlapping spiral arms forming an inner ring, and a star formation rate of 3.8 solar masses per year. Three supernovae have been observed in NGC 4902: SN 1979E, SN 1991X (a Type Ia), and SN 2011A (initially classified as Type IIn but suggested to be a supernova impostor).

Reader's Guide

The NGC 4902 Group is significant as a nearby galaxy group that offers a comparative scale to the Local Group, being of similar size. Its foremost galaxy, NGC 4902, provides a detailed case study of barred spiral structure, including a prominent bar, overlapping spiral arms forming an inner ring, and multiple spiral arms with many HII regions. The group's location within the Virgo Supercluster, specifically in the Virgo II Groups or Virgo Southern Extension, places it in a broader cosmic context. The observation of three supernovae in NGC 4902—including a Type Ia (SN 1991X) and a possible supernova impostor (SN 2011A)—adds to its legacy as a site of transient astrophysical events. The group's membership of four galaxies (NGC 4902, NGC 4887, NGC 4897, and NGC 4899) and its association with the same galaxy cloud as NGC 5054 highlight its role in understanding galaxy clustering and large-scale structure.