Frankenstein Galaxy UGC 1382 Much Larger Than Previously Thought
Posted on July 16, 2016
Astronomers have found that galaxy UGC 1382 is much larger than previously thought. It is now considered to be one of the largest isolated galaxies known. It is also known as the Frankenstein Galaxy because unlike most galaxies its insides are younger than its outsides.
UGC 1382 appeared to be a simple elliptical galaxy when using only optical data from the Sloan Digital Sky Survey (SDSS). Astronomers then discovered enormous spiral arms when ultraviolet data from the Galaxy Evolution Explorer (GALEX) and deep optical data from SDSS. The galaxy is even larger when combined with a with a view of low-density hydrogen gas (above). The galaxy is ten times larger than previous estimates.
Study co-author Mark Seibert of the Observatories of the Carnegie Institution for Science, says in a statement, "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. It is so delicate that a slight nudge from a neighbor would cause it to disintegrate.
Lea Hagen, a graduate student at Pennsylvania State University, says, "We saw spiral arms extending far outside this galaxy, which no one had noticed before, and which elliptical galaxies should not have. That put us on an expedition to find out what this galaxy is and how it formed."
The astronomers think the unique structure of UGC 1382 may have resulted from separate entities coming together, rather than a single entity that grew outward. Seibert says, "The center of UGC 1382 is actually younger than the spiral disk surrounding it. 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."
Hi-res imagery of the Frankenstein Galaxy can be downloaded here. A research paper on the study of the galaxy will be published in the Astrophysical Journal. The image below shows how the galaxy looks much smaller when observed solely with optical light.