Multiwavelength Atlas of Galaxies

Part 4:

Section 4.2.3 Interacting Galaxy: NGC 4676:

NGC 4676 is commonly known as 'The Mice' for obvious reasons. It consists of two galaxies, NGC 4676a (the northernmost galaxy) and NGC 4676b. It is 87 Mpc distant.

NGC 4676: Originally modelled by Toomre and Toomre (1972) as a tidal (gravitational) encounter between two galaxies, this scenario is confirmed by subsequent kinematical observations. The tidal model has both galaxies in a prograde¹ collision, with their northern edges rotating away from us, and NGC 4676a at a larger redshift than NGC 4676b.

HST NICMOS J,H and K imaging is presented in Rossa et al. (2007).

The VLA HI tails are extensive, as is the HII emission, showing evidence for widespread star formation (Hibbard and van Gorkom 1996) induced by the encounter.

¹The encounter is called prograde when the orbital spin angular momentum of the companion galaxy is aligned with the spin angular momentum of the target galaxy.