A new galaxy, much like our own

The extraordinary images — taken with NASA’s James Webb Space Telescope — show a galaxy that glitters with 10 distinct star clusters that formed at different times, much like our own Milky Way.

Cocooned in a diffuse arc, and resembling fireflies “dancing” on a summer night, the newly discovered galaxy — which the Wellesley team have dubbed the “Firefly Sparkle” — was taking shape around 600 million years after the Big Bang, around the same time that our own galaxy was beginning to take shape.

Wellesley College astronomer Lamiya Mowla is co-lead author of the paper, which was published Wednesday, Dec. 11, in Nature.

Mowla says the discovery is particularly important because the mass of the Firefly Sparkle is similar to what the Milky Way’s mass might have been at the same stage of development. (Other galaxies Webb has detected from this time period are significantly more massive.)

“These remarkable images give us an unprecedented picture of what our own galaxy might have looked like when it was being born,” Mowla says. “By examining these photos of the Firefly Sparkle, we can better understand how our own Milky Way took shape.”

Glimpses of a young galaxy forming in a way so similar to our own are unparalleled, Mowla says. The JWST images show a Milky Way-like galaxy in the early stages of its assembly in a universe that’s only 600 million years old.

“As an observational astronomer studying the structural evolution of astronomical objects in the early Universe, I want to understand how the first stars, star clusters, galaxies, and galaxy clusters formed in the infant Universe and how they changed as the Universe got older,” Mowla notes. Of the Firefly Sparkle, she says, “”I didn’t think it would be possible to resolve a galaxy that existed so early in the universe into so many distinct components, let alone find that its mass is similar to our own galaxy’s when it was in the process of forming.

“There is so much going on inside this tiny galaxy, including so many different phases of star formation,” Mowla told NASA. “These images are the very first glimpse of something that we’ll be able to study — and learn from — for many years to come.”

Mowla, who co-led the project with Kartheik Iyer, a NASA Hubble Fellow at Columbia University in New York, is an assistant professor of physics and astronomy at Wellesley, and a 2013 graduate of the college.