Hubble marks 30th anniversary year with portrait of massive barred spiral galaxy

The Hubble Space Telescope kicked off its 30th anniversary year with a new portrait of UGC 2885, a barred spiral galaxy that astronomers estimate is one of the largest in the local universe.

The massive galaxy is 2.5 times wider than the Milky Way and hosts ten times as many stars, but astronomers refer to it as a “gentle giant” because it has been sitting quietly for billions of years, boasting only modest rates of star formation.

The supermassive black hole at the center of UGC 2885 is also relatively quiet.

Because its diet doesn’t include much material from smaller satellite galaxies, the gentle giant must rely on its own internal hydrogen structures to fuel the birth of new stars.

The barred spiral galaxy, positioned within the constellation Perseus, is also sometimes referred to as “Rubin’s galaxy” — named for the influential American astronomer Vera Rubin.

“My research was in large part inspired by Vera Rubin’s work in 1980 on the size of this galaxy,” Benne Holwerda, astronomer at the University of Louisville who photographed the galaxy using the Hubble Space Telescope, said in a news release. “We consider this a commemorative image. The goal of citing Dr. Rubin in our observation was very much part of our original Hubble proposal.”

Astronomers remain somewhat befuddled by the massive size and quiet nature of UGC 2885. How did the spiral galaxy get so big while mostly avoiding violent collisions.

“It’s as big as you can make a disk galaxy without hitting anything else in space,” said Holwerda.

To find out how UGC 2885 got so big, Holwerda and his colleagues are surveying the globular star clusters located in the galaxy’s halo, or along the spiral galaxy’s outskirts. A large population of globular star clusters would suggest the galaxy swallowed up smaller satellite galaxies over many billions of years.

In the future, scientists hope to survey the galaxy’s center using the James Webb Space Telescope, set to launch in 2021.

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