DDO 169 (also known as UGC 8331) is an

irregular galaxy An irregular galaxy is a galaxy that does not have a distinct regular shape, unlike a spiral or an elliptical galaxy. Irregular galaxies do not fall into any of the regular classes of the Hubble sequence, and they are often chaotic in appearance, ...

located in the constellation

Canes Venatici Canes Venatici () is one of the 88 constellations designated by the International Astronomical Union (IAU). It is a small northern constellation that was created by Johannes Hevelius in the 17th century. Its name is Latin for 'hunting dogs', and ...

. It is a member of the

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 (M51A). Other notable members include the companion galaxy to the Whirlpool Galaxy ( M51B) and the S ...

of galaxies and measures approximately 5 × 1.5

kiloparsecs The parsec (symbol: pc) is a unit of length used to measure the large distances to astronomical objects outside the Solar System, approximately equal to or (au), i.e. . The parsec unit is obtained by the use of parallax and trigonometry, an ...

(16,000 × 5,000

lightyears A light-year, alternatively spelled light year, is a large unit of length used to express astronomical distances and is equivalent to about 9.46 trillion kilometers (), or 5.88 trillion miles ().One trillion here is taken to be 1012 ...

). 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 The rotation curve of a disc galaxy (also called a velocity curve) is a plot of the orbital speeds of visible stars or gas in that galaxy versus their radial distance from that galaxy's centre. It is typically rendered graphically as a plot, ...

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

megaparsec The parsec (symbol: pc) is a unit of length used to measure the large distances to astronomical objects outside the Solar System, approximately equal to or (au), i.e. . The parsec unit is obtained by the use of parallax and trigonometry, and ...

References

{{DEFAULTSORT:DDO 169 UGC 8331r UGC 8331 M51 Group 8331 46127