A lonely galactic island

Here is one of our universe’s dwarf irregular galaxies – a cousin to the two famous satellite galaxies to our own Milky Way, which are visible from Earth’s southern hemisphere and go by the names Large and Small Magellanic Clouds. The galaxy in this new Hubble Space Telescope image – which is known as DDO 190 – is 9 million light-years from Earth in contrast to 1 to 2 thousand light-years for the Magellanic Clouds. DDO 190 is different from the Magellanic Clouds in another way. It’s apparently not attached to a larger galaxy, but instead lies some 3 million light-years from any other galaxy in space. DDO 190 is truly a lonely galactic island on a sea of empty space.

This is the galaxy DDO 190 as seen by the NASA/ESA Hubble Space Telescope. It’s classified as a dwarf irregular galaxy. Its nearest neighbor among the galaxies is 3 million light-years away. Click here to enlarge this image. Image Credit: ESA/Hubble & NASA

In this image of DDO 190, you can see older, reddish stars populating the galaxy’s outskirts. Meanwhile, some younger, bluish stars can be seen in the crowded center of the galaxy. Some pockets of ionized gas heated up by stars appear here and there, with the most noticeable one shining towards the bottom of DDO 190 in this picture. Meanwhile, a great number of distant galaxies with evident spiral, elliptical and less-defined shapes glow in the background.

DDO 190 is considered part of the loosely associated Messier 94 group of galaxies, not far from the Local Group of galaxies that includes the Milky Way. It’s part of this larger group of galaxies, but, still, DDO 190 is on its own. The galaxy’s nearest dwarf galaxy neighbor, DDO 187, is thought to be no closer than 3 million light-years away. In contrast, many of the Milky Way’s companion galaxies, such as the Large and Small Magellanic Clouds, reside within a fifth or so of that distance, and even the giant spiral of the Andromeda Galaxy is closer to the Milky Way at about 2.2 million light-years than DDO 190 is to its nearest neighbor.

Read more about this image from NASA

Bottom line: The dwarf galaxies called the Large and Small Magellanic Clouds are only 100,000 to 200,000 light-years from Milky Way. The dwarf galaxy DD) 190 is 3 million light-years from any galaxy.

August 19, 2012

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