Like the monstrous creation of Dr. Victor Frankenstein, one bizarre galaxy far, far away is made up of the cosmic spare parts of other galaxies, according to NASA.
Located about 250 million light-years away from Earth, the galaxy designated UGC 1382 was initially thought to be old, small and typical.
But when a team of NASA scientists used telescopes and other observatories to investigate UGC 1382, they found that the galaxy is actually 10 times bigger than what was previously believed.
Accidental Discovery
Study co-authors Mark Seibert and Lea Hagen chanced upon UGC 1382 only by accident.
The pair of astronomers were originally looking for stars that form in run-of-the-mill elliptical galaxies. Instead of being flat disks, these galaxies are more football-shaped and three-dimensional, and do not spin.
Scientists had first thought UGC 1382 was one of these galaxies. But while examining ultraviolet light images of galaxies through the Galaxy Evolution Explorer (GALEX), researchers noticed something unusual.
Hagen, lead author of the study and a graduate student at Pennsylvania State University, says they saw spiral arms extending far outside UGC 1382, which no one had observed before and which typical elliptical galaxies should not have.
"That put us on an expedition to find out what this galaxy is and how it formed," says Hagen.
Bizarre Galaxy
Hagen and Seibert looked at the data of the galaxy gathered from other telescopes, including the Two Micron All-Sky Survey (2MASS), the Wide-field Infrared Survey Explorer (WISE) and the Sloan Digital Sky Survey, among many others.
After GALEX revealed previously unseen structures, infrared and optical light observations from other telescopes helped scientists build a new model of the bizarre galaxy.
Researchers found that UGC 1382, which is 718,000 light-years across, is about seven times wider than our own galaxy, the Milky Way. UGC 1382 is also one of the three biggest remote disk galaxies ever detected.
The galaxy is also a rotating disk of low-density gas. Because the gas is spread out, stars do not form in the galaxy very quickly.
But the biggest surprise for scientists was how the relative ages of the galaxy's parts appeared backwards.
In typical galaxies, the innermost portion, which forms first, contains the oldest stars. As these galaxies expand, newer regions contain the younger stars.
With UGC 1382, the situation is different. Thanks to observations from different telescopes, researchers discovered that the galaxy's center is younger than the spiral disk that surrounds it.
To put it simply, it's old on the outside and young on the inside. Seibert compares it to discovering a tree with inner growth rings that are younger than its outer rings.
Scientists suspect that the galaxy's unique structure may have been the result of separate entities combining, rather than one entity that grew outward. Two parts of the galaxy appear to have grown before merging.
Experts believe that more galaxies such as this may exist, but further research must be done to find them. The study will soon be published in the Astrophysical Journal.
