Anne’s Image of the Day: Dwarf Galaxy ESO 540-031

April 25, 2014

ESO 540-031, a dwarf irregular galaxy in Cetus

Image Credit: ESA/Hubble & NASA
Acknowledgement: Luca Limatola

ESO 540-031 (also known as DDO 6 and UGCA 15) is a dwarf irregular galaxy of 6,800 x 3,800 light-years in diameter, located about 11.25 million light-years away from Earth in the constellation of Cetus (the Whale), while is is receding from us at approximately 295 kilometers per second.

This dwarf galaxy is a member of the Sculptor Group, a loose group of some 13 galaxies near the south galactic pole. The group is one of the closest groups of galaxies to the Local Group, of which our Milky Way galaxy is a member; the distance to the center of the group from the Milky Way is some 12.7 million light-years.

Dwarf galaxies are among the smaller and dimmer members of the galactic family, typically only containing around a few hundred million stars. Although this sounds like a large number, it is small when compared to spiral galaxies like our Milky Way, which are made up of hundreds of billions of stars. The glittering specks in this image, resembling a distant flock of flying birds, are the stars that make up ESO 540-31.

This image was taken with the Advanced Camera for Surveys on the Hubble Space Telescope, using one infrared and one optical filter. The background of this image is full of many other galaxies, all located at vast distances from us. A version of this image was entered into the Hubble’s Hidden Treasures image processing competition by contestant Luca Limatola.