NGC 4725 - One-Armed Barred Spiral Galaxy in Coma Berenices

NGC 4725 is a distinctive ringed barred spiral galaxy (classification SAB(r)ab pec) in the constellation Canes Venatici, lying at a distance of roughly 40 million light-years. It is best known for its unusual and asymmetric appearance: a strong central bar surrounded by a prominent single outer spiral arm that wraps almost completely around the galaxy, rather than the more familiar two-armed pattern seen in many grand-design spirals. This lone arm gives NGC 4725 a slightly unbalanced look, making it an intriguing example of how spiral structure can deviate from textbook symmetry.

The galaxy’s inner regions are dominated by a bright bulge and a well-defined bar, which plays a key role in shaping its evolution by redistributing gas and stars within the disk. Encircling this is a subtle inner ring, a common feature in barred spirals, where gas accumulates and star formation can be enhanced. Dust lanes thread through the disk, tracing the flow of material along the bar and into the spiral structure, while the outer arm fades gradually into low-surface-brightness outskirts.

NGC 4725 is often discussed as a prototype of one-armed (m = 1) spiral structure, possibly driven by past gravitational interactions or internal dynamical instabilities. Its relatively nearby distance and clean orientation make it a valuable target for studying how bars, rings, and asymmetric arms coexist within a single galaxy.

This image is based on just 3 hours of LRGB integration captured with Telescope Live’s SPA-2-CCD.