Milky Way Analogue

Of course we don’t have a pretty picture of the Milky Way taken taken from outside the galaxy, but it looks probably very similar to NGC 3344: a thin disc of stars, with star formation and dust lanes along spiral arms, and a featureless bulge of stars in the centre.

In the Hubble diagram, spiral galaxies are classified based on the pitch angle of their arms, and the luminosity of the disc compared to the bulge.

By chance, we occasionally we see the disc of a spiral galaxy edge on. NGC 891 is an example of how thin the disc is. The black band is caused by dust, which obscures star light.

Such cosmic dust is thought to be produced by stars and supernovae.

The movie shows the three dimensional structure of this galaxy. It cycles between dark matter, gas, and stars, as in the “Small Cluster” example. Note how round the dark matter distribution is, compared to the thin distribution of stars. Both spin which tend to flatten them just as happens whenmaking pizza. However, as the gas cools by emitting radiation, it starts to spin much faster and collapses to a disc. The dark matter cannot because it is… dark.

You can download individual movies by clicking them below.

You can download all of the movies in a zipped folder here.