October 22, 2012
Astronomers Discover Elliptical Galaxy With Split Personality
Lee Rannals for redOrbit.com — Your Universe Online
While most elliptical galaxies are considered vintage, retired star making neighborhoods, astronomers have found one that has a personality more like that of a pinwheel-shaped spiral galaxy.
Centaurus A isn't considered to be a typical elliptical galaxy to begin with. It is known for its dark dust lane across its middle, which is a sign that it swallowed up a spiral galaxy about 300 million years ago.
"No other elliptical galaxy is known to have spiral arms," lead author of the study Daniel Espada, said in a press release. "Centaurus A may be an old galaxy, but it's still very young at heart."
When Centaurus A consumed the spiral galaxy, it ate up its gases, forming a disk that can be seen nearly edge on. From Earth's perspective, any features in the disk have been hidden by the intervening dust.
The astronomers used the sharp vision of the Smithsonian's Submillimeter Array in order to look past the dust and see the disk's structure. The telescope can see through dust to pick up signals from naturally occurring carbon monoxide gas.
Astronomers were able to use this gas to map out and unveil two distinct spiral arms within the galaxy's core. These tendrils have sizes and shapes similar to spiral arms in galaxies like the Milky Way. Also, like spiral galaxies, they are able to form new generations of stars.
Computer simulations suggest the spiral features may endure for hundreds of millions of years to come.
Centaurus A is the first elliptical galaxy found to have spiral arms. The split-personality galaxy is just 12 million light years away from Earth, making it easy to study.
Espada said the team would definitely be using the Atacama Large Millimeter/submillimeter Array (ALMA) to search for other objects similar to Centaurus A.
The astronomers published their findings in The Astrophysical Journal Letters.