Mice Galaxies

NGC 4676, or the Mice Galaxies, are two spiral galaxies in the constellation Coma Berenices. About 290 million light-years away,[2] they began the process of colliding and merging. Their name refers to the long tails produced by tidal action—the relative difference between gravitational pulls on the near and far parts of each galaxy—known here as a galactic tide. It is a possibility that both galaxies, which are members of the Coma cluster,[3] have experienced collision, and will continue colliding until they coalesce.

NGC 4676A / 4676B
The Mice Galaxies, NGC 4676A (right)/NGC 4676B (left)
Observation data (J2000 epoch)
Constellation	Coma Berenices
Right ascension	12h 46m 10.1s / 12h 46m 11.2s[1]
Declination	+30° 43′ 55″ / +30° 43′ 22″[1]
Redshift	6613 ± 8 / 6607 ± 7 km/s[1]
Distance	290 Mly (89 Mpc)[2]
Apparent magnitude (V)	14.7 / 14.4[1]
Characteristics
Type	Irr / SB(s)0/a pec[1]
Size	760,000 ly (233 kpc) (estimated)[lower-alpha 1]
Apparent size (V)	2′.3 × 0′.7 / 2′.2 × 0′.8[1]
Notable features	Interacting galaxies
Other designations
Mice Galaxies,[1] IC 819 / 820,[1] UGC 7938 / 7939,[1] PGC 43062 / 43065,[1] Arp 242[1]

The colors of the galaxy are peculiar. In NGC 4676A a core with some dark markings is surrounded by a bluish white remnant of spiral arms. The tail is unusual, starting out blue and terminating in a more yellowish color, despite the fact that the beginning of each arm in virtually every spiral galaxy starts yellow and terminates in a bluish color. NGC 4676B has a yellowish core and two arcs; arm remnants underneath are bluish as well.

The galaxies were photographed in 2002 by the Hubble Space Telescope.[4] In the background of the Mice Galaxies, there are at least 3300 galaxies, at distances up to 13 billion light-years.