The Cosmic Web

(This was meant to come out on Tuesday as is traditional, but some sort of vengeful internet gnome seems to have prevented it. Well, here it is.)

Here’s a new image from the Hubble Space Telescope - specifically, the Wide Field Camera 3 which was successfully installed this May. The picture’s of an area that Hubble’s photographed before, producing the famous Ultra Deep Field image containing some 10,000 distant galaxies. This new picture repeats the feat in near infrared light (for the benefit of human eyes the colours have been shifted, so the light which now appears red is really in the farther infrared, while the blue is only just outside our visible range).

New Hubble Ultra-Deep Filed in infrared. Click for credit and larger versions.

Take a moment to look into that picture. Each of those tiny blobs is a galaxy.

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Lots of galaxies are spiral-shaped like our Milky Way. Some we see face-on and some edge-on, depending on their orientation towards the Earth. Those which look edge-on are generally pretty flat, sometimes with a pronounced bulge in the disk’s centre.

ESO 510-G13. Click for Hubblesight release.

But not this galaxy, the charmingly-named ESO 510-G13. Its disk, which we can see perfectly edge-on, has a definite warp to it as though someone had grabbed the edges and given it a twist. In fact this is evidence of a recent collision with another galaxy, whose gravitational effect has shifted millions of stars huge gas clouds off their orbits. The disk is being rippled through by titanically slow waves of density, like a pool’s surface after a bucket of water’s dumped into it. Although the shape of the starry and gassy components of the disk is hard to make out against the bright glow of the central bulge, the warp is easy to spot because of the dark dust lanes running through the disk. This dust, made up of tiny particles a fraction of a millimeter in diameter, absorbs and scatters the starlight from behind it.

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