PASADENA, Calif., July 11 (UPI) -- For a half-century, astronomers believed UGC 1382 was small elliptical galaxy -- not all that interesting. For a half-century, astronomers were fooled.
UGC 1382 isn't a small, boring galaxy, it's a potential record-breaker. According to new analysis, UGC 1382 is a colossal Giant Low Surface Brightness disk galaxy. Its size rivals Malin 1, a disk galaxy with a diameter seven times that of the Milky Way.
The revelation is a reminder that the cosmos offers a wide range of illusions.
After a handful of surveys over more than five decades, it wasn't until 2009 that astronomers saw something unusual surrounding UGC 1382 -- a faint signature of a rotating hydrogen disk. But there was no follow-up.
More recently, astronomers realized UGC 1382 was not as it seemed while surveying star formation in early-type galaxies.
"We saw [star formation] in the ultraviolet part of the spectrum spiral arms were visible--something you do not expect to see around elliptical galaxies," Mark Seibert, an astronomer at the Carnegie Institution for Science, said in a news release. "Naturally, that finding sent us off on a very different path!"
A more thorough analysis revealed the presence -- and tremendous size -- of the rotating hydrogen disk.
Giant Low Surface Brightness disk galaxies are one of the most massive types of isolated spiral galaxies. But only a small, inner portion is bright enough to be easily detected. Since the 1960s, astronomers only recognized the presence of the inner portion of UGC 1382.
In total, the galaxy stretches 220 kiloparsecs across. The Milky Way has a diameter of just 30 kiloparsecs. A parsec is the equivalent of 3.26 light-years, 19 trillion miles.
The surprisingly massive galaxy is much closer to Earth than Malin 1, opening up a wealth of new research opportunities, including investigations into the origins and evolution of these extreme systems.
"By understanding this galaxy, we can get clues to how galaxies form on a larger scale, and uncover more galactic neighborhood surprises," Hagen concluded.