From the distant Universe, light has traveled for some 10.7 billion years from distant galaxy MACSJ2129–1, lensed, distorted and magnified by the foreground clusters imaged here. Image credit: NASA, ESA, and S. Toft (University of Copenhagen) Acknowledgment: NASA, ESA, M. Postman (STScI), and the CLASH team.

Discovery of a young, dead galaxy creates a huge puzzle for astronomers

At just 3 billion years old, this galaxy should be blue and full of new, young stars. Instead, it’s already out of fuel. What gives?

“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. 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.” -Sune Toft

The life-cycle of a galaxy is straightforward and inevitable: normal and dark matter gravitationally attract, creating a large collection of mass.

Within a dark matter halo, the normal matter collects towards the center. When the densities reach large enough amounts, gas clouds collapse, forming new stars within. Image credit: J. Turner.

The normal matter collects in the center, forming stars and pancaking into a disk.