Wednesday, November 20, 2013

Astronomy Picture of the Day: 11/20/13 - The Cartwheel Galaxy

There is no doubt that this is one of the most stunningly beautiful galaxies in the observable universe. This, ladies and gentlemen, is a lenticular galaxy named the "cartwheel galaxy" (which tends to look more like a Ferris wheel to my eyes, but whatever). It"s located about 400 million light-years away from Earth in the constellation of Sculptor.

This image is a false-colored composite, put together using 4 separate images taken of the region at various wavelengths. Infrared data was collected by the Spitzer Space Telescope (seen in red), ultraviolet data came from the now-defunct "Galaxy Evolution Explorer" [GALEX] (pictured in blue), x-ray information was derived from the Chandra X-ray Observatory (purple) and visible light data was gathered by the Hubble Space Telescope. The galaxy likely gets its rather unique shape from a collision with a smaller galaxy that took place several hundreds of millions of years ago.

Prior to the collision, the galaxy was probably a spiral galaxy. After the collision took place, the galaxy underwent ferocious cycles of star formation. As you can see, the outer bounds of the galaxy"s rim has several hundreds of thousands of low-mass blue stars that live short lives, before exploding as beautiful supernovae blasts -- leaving behind dense stellar cores, called neutron stars (other times, stellar-mass black holes are created).

The diameter of the galaxy is about 50,000 light-years larger than our home galaxy, the Milky Way. This particular galaxy emits a large amount of infrared energy and x-ray radiation, likely due to the unusually high number of black holes located there. Many of which have a neighboring companion star, which they cannibalize on - releasing x-rays as a result. The "spokes" connecting the outer rim of the galaxy to the central core are non-thermal radio and optical spokes.

Sources & Further Reading:

Image Credit: Composite: NASA/JPL/Caltech/P.Appleton et al. X-ray: NASA/CXC/A.Wolter & G.Trinchieri et al.

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