ALMA Discovers a Cosmic 'Dinosaur Egg' about to Hatch in the Early Universe

Globular clusters are among the oldest objects in the universe. Now, scientists have discovered a newborn example of one of these clusters, revealing a bit more about the rare conditions needed to create new ones.

"We may be witnessing one of the most ancient and extreme modes of star formation in the universe," said Kelsey Johnson, the lead author of the new paper, in a news release. "This remarkable object looks like it was plucked straight out of the very early universe. To discover something that has all the characteristics of a globular cluster, yet has not begun making stars, is like finding a dinosaur egg that's about to hatch."

The object in this case was spotted using the Atacama Large Millimeter/submillimeter Array (ALMA), and is referred to as the "Firecracker." It can be found about 50 million light-years away from Earth, nestled inside two interacting galaxies, which are collectively known as the Antennae galaxies. The tidal forces generated by their ongoing merger are triggering star formation on a colossal scale.

With ALMA, the scientists found a pristine example of a globular cluster before stars changed its unique characteristics. This gave researchers the first-ever glimpse of the conditions that may have led to the formation of many, if not all globular clusters.

"Until now, clouds with this potential have only been seen as teenagers, after star formation had begun," said Johnson. "That meant that the nursery had already been disturbed. To understand how a globular cluster forms, you need to see its true beginnings."

The survival rate for massive young star clusters remaining intact is very low-around one percent. However, this latest object, which contains 50 million times the mass of the sun in molecular gas, may be sufficiently dense that it has a good chance of being one of the ones that do survive.

The findings reveal a bit more about globular clusters and show how they evolve over time.

The findings are published in The Astrophysical Journal.

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