# NGC 1052-DF2

NGC 1052-DF2
Observations of NGC 1052-DF2 show lack of dark matter.[1]
Observation data
ConstellationCetus
Right ascension02h 41m 46.8s[2]
Declination−08° 24′ 12″[2]
Distance (comoving)19.0 ± 1.7 Mpc (62.0 ± 5.5 Mly)[2]
Characteristics
TypeSp...[3]
Mass2×108[2] M
Apparent size (V)1.20′ × 1.12′[3]
Other designations
PGC 3097693[3]

NGC 1052-DF2 is an ultra diffuse galaxy in the constellation Cetus, which was identified in a wide-field imaging survey of the NGC 1052 group by the Dragonfly Telephoto Array.[2] It has been proposed that the galaxy contains little or no dark matter, the first such discovery. However, follow-up studies have not confirmed this.

The distance to the galaxy, derived by surface brightness fluctuation, is 19 ${\displaystyle \pm }$ 1.7 Mpc. Due to close proximity, it is assumed to be associated with the elliptical galaxy NGC 1052 and to lie at a distance of about 20 Mpc.

The apparent lack of dark matter in NGC 1052-DF2 may help prove that dark matter is real: if what appears to be dark matter is really just a currently unknown effect of the gravity of ordinary matter then this apparent dark matter should also appear in this galaxy. Further study will be needed before this and any other possible implications can be confirmed.[4][5] If confirmed, the absence of dark matter may also have implications for theories of galaxy formation, as dark matter has been thought to be needed for galaxy formation.[5]

Later studies have failed to confirm the lack of dark matter, and shown only that it is likely to have a mass-to-light ratio towards the low end of expected values for a dwarf galaxy.[6]