16-05 Galaxy Collisions

The Antennae (NGC 4038, 4039) and the Mice (NGC 4676)

[Tidal force distorts galaxies and induces star formation.]

 

Passing by... the case of M51

[Colissions may produce spiral arms.]

 

Galaxies collide much more often than stars.

[The M81 group, 1 degree across, 3.5 Mpc away. Left: Palomar Sky Survey. Right: VLA HI measurement.]

 

Our Milky Way is eating a dwarf elliptical, may have hydrogen gas links with LMC and SMC, and will collide with M31 in 6 Gyrs...