Small Elliptical Galaxy is Actually a Gigantic Cosmic ‘Frankenstein,’ Scientists Say
What was thought to be a small, nondescript elliptical galaxy turned out to be a giant 'Frankenstein' galaxy, scientists said.
The UGC 1382, which lies an estimated 250 million light-years from Earth, was believed to be a small and unexceptional elliptical galaxy. But astronomers have discovered that the UGC 1382 is actually spiral and 718,000 light-years wide, which means it is seven-times bigger than the Milky Way galaxy.
Moreover, scientists also found that, unlike most galaxies, its insides are younger than its outsides, and it appears to be made up of cosmic spare parts.
"This rare, 'Frankenstein' galaxy formed and is able to survive because it lies in a quiet little suburban neighborhood of the universe, where none of the hubbub of the more crowded parts can bother it," Mark Seibert of the Observatories of the Carnegie Institution for Science in California and co-author of the study, said in a news release.
"It is so delicate that a slight nudge from a neighbor would cause it to disintegrate."
Ellipticals are known to be the most common type of galaxy and lack the spiral structure of disks like that of the Earth's Milky Way. Seibert and fellow astronomers were observing the stars forming in elliptical galaxies using ultraviolet light through data from NASA's Galaxy Evolution Explorer (GALEX) when they noticed something strange about the UGC 1382.
"We saw spiral arms extending far outside this galaxy, which no one had noticed before, and which elliptical galaxies should not have," Lea Hagen from Pennsylvania State University and lead author of the study said in a statement.
"That put us on an expedition to find out what this galaxy is and how it formed."
The researchers built a new model of the UGC 1382 using data from other telescopes, including the Sloan Digital Sky Survey, the Two Micron All-Sky Survey (2MASS), NASA's Wide-Field Infrared Survey Explorer (WISE), the National Radio Astronomy Observatory's Very Large Array and Carnegie's du Pont Telescope at Las Campanas Observatory.
They found that the galaxy's inside-out structure might have been a result of separate entities coming together, with each of the two parts evolving independently before merging.
The research team believes that the UGC 1382 first consisted of a group of small galaxies made of gas and dark matter, and then later, a lenticular galaxy - a spinning disk without spiral arms - may have formed nearby. Then the small galaxies may have begun orbiting the lenticular galaxy, thus forming the big structure that is seen today.
According to the scientists, they will be conducting more research to learn about the formation scenario and to find out if other galaxies like the UGC 1382 exist.