UGC 8331 is an irregular galaxy

Irregular galaxy

An irregular galaxy is a galaxy that does not have a distinct regular shape, like a spiral or an elliptical galaxy. The shape of an irregular galaxy is uncommon – they do not fall into any of the regular classes of the Hubble sequence, and they are often chaotic in appearance, with neither a...

 located in the constellation Canes Venatici

Canes Venatici

Canes Venatici is one of the 88 official modern constellations. It is a small northern constellation that was created by Johannes Hevelius in the 17th century. Its name is Latin for "hunting dogs", and the constellation is often depicted in illustrations as representing the dogs of Boötes the...

. It is a member of the M51 Group

M51 Group

The M51 Group is a group of galaxies located in Canes Venatici. The group is named after the brightest galaxy in the group, the Whirlpool Galaxy...

 of galaxies and measures approximately 5 x 1.5 kiloparsecs (16,000 x 5,000 lightyears). The galaxy's large-scale structure is very unorganized and it has two clusters of stars in its outer portions in addition to the cluster in the center. These clusters make it practically impossible to determine the galaxy's rotation curve

Galaxy rotation curve

The rotation curve of a galaxy can be represented by a graph that plots the orbital velocity of the stars or gas in the galaxy on the y-axis against the distance from the center of the galaxy on the x-axis....

 and contributes to a large variation in distance figures that are derived with different methods. The exact distance to the galaxy is not known, although a 1998 paper estimated the distance as 8.23 megaparsecs.