Astronomers discover huge 'dead' disk-shaped galaxy

New Delhi: Astronomers using NASA's Hubble Space Telescope have discovered a first-of-its-kind compact yet massive, disk-shaped 'dead' galaxy that stopped making stars just a few billion years after the Big Bang.

The discovery challenges the current understanding of how massive galaxies form and evolve, researchers said.

With the help of the Hubble telescope, researchers from the University of Copenhagen in Denmark photographed the galaxy and were able to see into the centre of the dead galaxy - where star formation has stopped.

They were expecting to see a chaotic ball of stars formed through galaxies merging together. Instead, they saw evidence that the stars were born in a pancake-shaped disk.

This is the first direct observational evidence that at least some of the earliest so-called "dead" galaxies somehow evolve from a Milky Way-shaped disk into the giant elliptical galaxies we see today, researchers said.

This is a surprise because elliptical galaxies contain older stars, while spiral galaxies typically contain younger blue stars.

At least some of these early "dead" disk galaxies must have gone through major makeovers. They not only changed their structure, but also the motions of their stars to make a shape of an elliptical galaxy, the team said.

"This new insight may force us to rethink the whole cosmological context of how galaxies burn out early on and evolve into local elliptical-shaped galaxies," said Sune Toft from University of Copenhagen.

"Perhaps we have been blind to the fact that early 'dead' galaxies could in fact be disks, simply because we haven't been able to resolve them," Toft said.

(With PTI inputs)