Scientists discover a weird ‘Frankenstein’ galaxy, younger than its outsides

But for UGC 1382, the galaxy’s centre was younger than its outside.

Astronomers with the Carnegie Institution for Science ran a series of multi-wavelength surveys on the distant galaxy and discovered that it’s actually a disk-shaped low surface brightness galaxy, the term for a galaxy that emits less light than normal galaxies.

UGC 1382, which lies about 250 million light-years from Earth, had always been regarded as an old, small and ordinary elliptical galaxy.

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.

“We call it the Frankenstein galaxy because it formed out of a couple different galaxies”, said Lea Hagen, a graduate student at Pennsylvania State University who led the study.

They had been looking for stars forming in run-of-the-mill elliptical galaxies, which do not spin and are more 3D and football-shaped than flat disks.

The mediocre-looking UGC 1382 is now thought to be around 718,000 light-years in diameter. We think what happened is you had some tiny dwarf galaxies and then a few billion years later another galaxy formed nearby. Optical and infrared light observations from the other telescopes allowed the researchers to build a new model of the mysterious galaxy. It’s more than seven times wider than the Milky Way, and has spiral arms extending out of the galaxy, which ordinary elliptical galaxies wouldn’t have.

No one can confirm at this point, but it is like the galaxy was created from an accident. They are very rare and have two components: what is known as a high surface brightness disk galaxy, with an extended low surface brightness disk surrounding it. So why was galaxy UGC1382 so misconstrued before?

Seibert says this discovery could helps astronomers and astrophysicists understand more about the evolution and formation of galaxies.

The biggest surprise was the finding that unlike most galaxies, in which the oldest stars are located in the inner regions and the newer ones further out, UGC 1382 has the opposite arrangement.

They dubbed it a Frankenstein galaxy, where the inside and outside formed differently before merging.

To put it simply, it’s old on the outside and young on the inside. “This is like finding a tree whose inner growth rings are younger than the outer rings”, Seibert said.

Scientists suspect that the galaxy’s unique structure may have been the result of separate entities combining, rather than one entity that grew outward.

Seibert explains: “Although there have been numerous surveys of the now-defunct elliptical since it was first cataloged in the 1960s, the only indication that it may be an unusual system was in 2009 when another survey indicated that there may be a hint of a rotating hydrogen disk, but it was not followed up”.

Before this merging, their research suggested, it is likely that a group of smaller galaxies existed there dominated by gas and dark matter, but around 3bn years ago another galaxy would have fallen into orbit with it leading to the wide galaxy we see today.

Scientists believe that there may be more similar galaxies that require thorough research.

“By understanding this galaxy, we can get clues to how galaxies form on a larger scale, and uncover more galactic neighborhood surprises”, Hagen said.

The GALEX mission, which ended in 2013 after more than a decade of scanning the skies in ultraviolet light, was led by scientists at Caltech in Pasadena, California.