Wednesday, August 31, 2011

ESO VLT looks into the eyes of the Virgin

Astronomers using the Very Large Telescope, at the European Southern Observatory's (ESO) Cerro Paranal facility in Chile, announce that they were recently able to capture a remarkable new image of a galactic duo called The Eyes.

Another reason why this image is very important is that it's the first-ever to be created through the ESO Cosmic Gems program, a public outreach initiative, meant to get more people involved with the field of astronomy.

As the name suggests, the program will mostly focus on either known or extremely interesting cosmic features that have something special over other objects or structures in their respective classes. ESO hopes that this will make more students interested in what's going on in space.

To that end, imaging this beautiful, yet peculiar pair of galaxies appeared to be the logical thing to do. NGC 4438, the larger galaxy in the system, did not always look like this. In fact, hundreds of millions of years ago, it was a majestic spiral galaxies.

Repeated collisions with surrounding dwarf galaxies eventually ripped its beautiful structure apart, leaving only this stained formation behind. However, the past events made the galaxy look like the pair of NGC 4435, its companion.

When viewed through a moderate-sized telescope, both galaxies appear as a bright set of eyes in the constellation of Virgo (the Virgin). The galaxies themselves are an estimated 100,000 light-years apart from each other, a distance smaller than the diameter of the Milky Way.

The interacting structures are located an estimated 50 million light-years away from Earth, which is relatively close in cosmic terms. This is also the reason why they can be effortlessly observed with a moderate-sized telescope on a dark night.

Interestingly, the cores of NGC 4438 and NGC 4435 look similar, but their edges couldn't be more different. While the former still contains vast amounts of cosmic dust and hydrogen gas, the smaller one is literally devoid of such materials, which implies it no longer forms blue stars.

“Some astronomers believe that the damage caused to NGC 4438 resulted from an approach between the two galaxies to within about 16 000 light-years that happened some 100 million years ago,” an ESO press release accompanying the findings expalins.

“But while the larger galaxy was damaged, the smaller one was significantly more affected by the collision. Gravitational tides from this clash are probably responsible for ripping away the contents of NGC 4438, and for reducing NGC 4435’s mass and removing most of its gas and dust,” they add.

“Another possibility is that the giant elliptical galaxy Messier 86, further away from The Eyes and not visible in this image, was responsible for the damage caused to NGC 4438,” the team concludes.

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