June 3, 2013
ESO 318-13, a dwarf galaxy in Antlia
Image Credit: ESA/Hubble & NASA
ESO 318-13 (also known as the Glitter Galaxy) is an oval-shaped irregular dwarf galaxy located roughly 20 to 30 million light-years away from Earth in the southern constellation of Antlia (the Pump). It is receding from us at approximately 720 kilometers per second. In this image, we see the galaxy along its edge.
Despite its distance, the stars captured in this image are so bright and clear you could almost attempt to count them. However, little is known about this small galaxy and the image doesn’t show us much of the galaxy’s structure. There are a few small blue-looking clumps of stars in the left part of the galaxy that look like young clusters. Judging from its brightness it’s only about 1 percent or less the mass of our Milky Way, and it’s mostly made up of stars. There’s not a hint of gas or dust.
We can also see many distant galaxies with distinct spiral and elliptical shapes scattered throughout the image, as well as several stars, near and far. One that particularly stands out is located near the center of the image, and looks like an extremely bright star located within the galaxy. This is, however, a trick of perspective. The star is located in our own Milky Way galaxy, and it shines so brightly because it is so much closer to us than ESO 318-13.
Peeking through ESO 318-13, near the right-hand edge of the image, is a distant spiral galaxy we see face-on. This is another indication that the galaxy is mostly stars and doesn’t have much gas and dust, otherwise that more distant galaxy would be heavily obscured, but as it is we can see it pretty well.
Galaxies are largely made up of empty space; the stars within them only take up a small volume, and providing a galaxy is not too dusty, it can be largely transparent to light coming from the background. This makes overlapping galaxies like these quite common.
This false color image was taken with the Advanced Camera for Surveys on the Hubble Space Telescope. The astronomers used two filters, one that lets through only orange/red light (shown as blue), and another that lets through only infrared light (shown as red).