NASA spots 'Godzilla Galaxy', 2.5 times wider than the Milky Way with 10 times as many stars
Scientists have discovered a galaxy, which could very well be the largest known in the local universe. The spiral galaxy — UGC 2885 — is 2.5 times wider than our Milky Way and packs 10 times as many stars.
Owing to its monstrous size, NASA says that it might earn the nickname "Godzilla Galaxy".
The galaxy is far away from the Milky Way: it is located 232 million light-years away in the northern constellation of Perseus. The discovery was made possible by the Hubble Space Telescope.
However, despite its gigantic size, researchers are calling it a "gentle giant" because it looks as if it has been sitting quietly over billions of years, possibly sipping hydrogen from the filamentary structure of intergalactic space.
According to experts, this is fuelling "modest" ongoing star birth at a rate of half that of our Milky Way.
"Its supermassive central black hole is a sleeping giant, too. Because the galaxy does not appear to be feeding on much smaller satellite galaxies, it is starved of infalling gas," says NASA.
The galaxy has also been nicknamed "Rubin's Galaxy", after astronomer Vera Rubin (1928-2016), who studied the galaxy's rotation rate in search of dark matter. It has been named so by Benne Holwerda of the University of Louisville, Kentucky, who observed the galaxy with the Hubble Space Telescope.
Rubin measured the galaxy's rotation, which provides evidence for dark matter, which makes up most of the galaxy's mass as measured by the rotation rate.
“My research was in a large part inspired by Vera Rubin's work in 1980 on the size of this galaxy,” says Holwerda.
Scientists are now trying to understand how the galaxy got so big — whether it ate up smaller satellite galaxies over time or simply accreted gas to make new stars.
Experts say a possible explanation could be that it is "fairly isolated" in space and does not have nearby galaxies to crash into and "disrupt the shape of its disk".
Using Hubble, researchers are counting the number of "globular star clusters" in the galaxy's halo — a vast shell of faint stars surrounding the galaxy. The findings have also been presented at the winter American Astronomical Society meeting in Honolulu, Hawaii.
"We present our first results on the globular cluster population of this massive disk galaxy, which we propose to rename 'Rubin's Galaxy'," says the abstract.
It says: "UGC 2885 was discovered to be the most extended disk galaxy (250 kpc diameter) by Vera Rubin in the 1980s. It is close enough for HST observations to resolve the globular cluster population."
"This galaxy is a substantially more extended and massive disk than any whose cluster population has been studied before. Cold dark matter galaxy assembly implies that the globular cluster population comes from smaller accreted systems and the disk — and the clusters associated with it — predominantly from gas accretion, matching angular momentum to the disk's," the abstract added.
NASA's upcoming James Webb Space Telescope could be used to explore the center of this galaxy as well as the globular cluster population. NASA's planned Wide Field Infrared Survey Telescope (WFIRST) would also give a census of this galaxy's cluster population, as well as of the halo.
"The infrared capability of both space telescopes would give us a more unimpeded view of the underlying stellar populations," says Holwerda.