II Zwicky 28

II Zwicky 28 is an interacting ring galaxy at a distance of approximately 390 million light-years. The sparkling pink and purple loop in Zw II 28 is not a typical ring galaxy due to the fact that it doesn’t seem to have the usual visible central companion.[2] For many years it was thought to be a lone circle on the sky, but observations using the Hubble Space Telescope have shown that there may be a possible companion lurking just inside the ring, where the loop appears to double back on itself.[2]

II Zwicky 28
Ring galaxy II Zwicky 28 imaged by the Hubble Space Telescope
Observation data (J2000 epoch)
Constellation	Orion
Right ascension	05h 01m 42.0s
Declination	+03° 34′ 28″
Redshift	0.028630 +/- 0.000060[1]
Helio radial velocity	8583 +/-18 km/s [1]
Distance	390 Mly (120 mpc)[1]
Apparent magnitude (V)	15.5
Characteristics
Type	S pec (Ring)
Apparent size (V)	0.3' x 0.3'[1]
Other designations
VV 790b, 2MASX J05014205+0334278, PGC 016572

The galaxy is only a faint IRAS source, which may indicate a lower level of star formation than other rings, however it has a high Hα luminosity, similar to other ring galaxies. It displays strong Balmer absorption lines interior to the ring, and it is possible that a major burst of star formation has recently occurred, using up a large fraction of the galaxy's molecular reservoir, and depleting its dust content.[3]