NGC 3718

Lore & Background

NGC 3718 exhibits a distinctive warped, S-shaped morphology similar to that of NGC 6872, with a prominent dust lane crossing and obscuring its central bulge. The innermost disc of gas follows this dust lane and has a polar orbit around the galaxy's center, classifying it as a polar-ring galaxy. This unique structure is thought to represent an early evolutionary stage for such galaxies, possibly resulting from gravitational interaction with the nearby spiral galaxy NGC 3729, located 150,000 light-years away.

Nearby, the Hickson Compact Group 56 (HCG 56) can be seen south of one of NGC 3718's spiral arms. HCG 56 is a compact group of galaxies, four of which are interacting with each other and expected to eventually merge into a single large elliptical galaxy. This group is about eight times farther away than NGC 3718 and NGC 3729, at a distance of approximately 120 Mpc. The edge-on galaxy in the field is not part of the group but lies slightly farther back.

NGC 3718 is a member of the Ursa Major Cluster.

Reader's Guide

NGC 3718 holds significance as a key example of a polar-ring galaxy in an early stage of evolution, offering insights into how such unusual structures form. Its warped S-shape and prominent dust lane, combined with the polar orbit of its inner gas disc, make it a valuable object for studying galactic morphology and dynamics. The gravitational interaction with its neighbor NGC 3729 is considered a likely cause of its distorted shape, providing a case study in how galaxy interactions can reshape galactic structure. Additionally, the presence of the much more distant Hickson Compact Group 56 in the same field of view adds context for comparative studies of galaxy groups at different distances. As a member of the Ursa Major Cluster, NGC 3718 contributes to understanding the distribution and evolution of galaxies within that cluster. Its classification as Arp 214 in the Atlas of Peculiar Galaxies further underscores its status as an object of special interest for astronomers investigating peculiar and interacting galaxies.

Did You Know?

• NGC 3718 is also cataloged as Arp 214.
• Its innermost gas disc follows a polar orbit around the galaxy's center, making it a polar-ring galaxy.
• The galaxy's warped S-shape is similar to that of NGC 6872.
• The Hickson Compact Group 56, located south of NGC 3718, is about eight times farther away.