The M109 Group (also known as the NGC 3992 Group or Ursa Major cloud) is a

group of galaxies A galaxy group or group of galaxies (GrG) is an aggregation of galaxies comprising about 50 or fewer gravitationally bound members, each at least as luminous as the Milky Way (about 1010 times the luminosity of the Sun); collections of galaxies ...

about 55 million

light-year A light-year, alternatively spelled light year (ly or lyr), is a unit of length used to express astronomical distances and is equal to exactly , which is approximately 9.46 trillion km or 5.88 trillion mi. As defined by the International Astr ...

s awayThe Ursa Major Groups
/ref> in the

constellation A constellation is an area on the celestial sphere in which a group of visible stars forms Asterism (astronomy), a perceived pattern or outline, typically representing an animal, mythological subject, or inanimate object. The first constellati ...

Ursa Major Ursa Major, also known as the Great Bear, is a constellation in the Northern Sky, whose associated mythology likely dates back into prehistory. Its Latin name means "greater (or larger) bear", referring to and contrasting it with nearby Ursa M ...

. The group is named after the brightest galaxy within the group, the

spiral galaxy Spiral galaxies form a galaxy morphological classification, class of galaxy originally described by Edwin Hubble in his 1936 work ''The Realm of the Nebulae''

M109.

Members

The table below lists galaxies that have been consistently identified as group members in the Nearby Galaxies Catalog, the survey of Fouque et al., the Lyons Groups of Galaxies (LGG) Catalogue, and the three group lists created from the Nearby Optical Galaxy sample of Giuricin et al. Galaxies frequently but not consistently listed as group members in the above references (i.e. galaxies listed in four of the above lists) include NGC 3631, NGC 3657, NGC 3733, NGC 3756, NGC 3850, NGC 3898, NGC 3985, NGC 3990, NGC 3998, NGC 4217, NGC 4220, UGC 6773, UGC 6802, UGC 6816, UGC 6922, and UGC 6969. The exact membership and the exact number of galaxies in the group is somewhat uncertain. Fouque et al. lists these galaxies as two separate groups named ''Ursa Major I North'' and ''Ursa Major I South'', both of which were used to compile the above table. Most other references, however, identify this as a single group, as is specifically noted in the LGG Catalogue.

References

{{reflist Ursa Major Cluster Ursa Major Virgo Supercluster