Animation of a projected view of a simulated Auriga galaxy that looks particuarly like our Galaxy; there is a bar of stars running through its centre very similar to the Milky Way. Viewed from the side, the simulated galaxy has a prominent X-shape, also called a boxy-peanut bulge. The peanut is made up of stars that get kicked out of the plane of the disc, because their orbits are excited by the rotating bar (much like a child on a swing reaching higher and higher heights if pushed at the right frequency). So, when we look at all the stars in projection, the result is a shape that looks like an X, or a shelled peanut. By the way, we also know that there is a peanut at the heart of our own Milky Way - so X really does mark the spot, or in this case, the centre of our Galaxy.

Movie showing the evolution of one of the simulations from very high redshift to present day. The movie fades between dark matter density, gas density, stars, metallicity and magnetic field strength. In the last of these, field lines indicate the directions of the magnetic field. Click here to see a higher resolution version, and here to see an even higher resolution version!

Movie showing the evolution of a simulated halo from very early times to the present day, showing dark matter density (left), gas density (middle), stars (right).