The galaxy, MACS2129-1, is described as a dead-disk galaxy. Astronomers made a surprising discovery—the first example of a compact yet massive, fast-spinning, disk-shaped galaxy that stopped making stars only a few billion years after the big bang.
This is the first direct observational evidence that at least some of the earliest so-called “dead” galaxies — where star formation stopped — somehow evolve from a Milky Way-shaped disk into the giant elliptical galaxies we see today.
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.
Previous studies of distant dead galaxies have assumed that their structure is similar to the local elliptical galaxies they will evolve into. Confirming this assumption in principle requires more powerful space telescopes than are currently available.
However, through the phenomenon known as “gravitational lensing,” a massive, foreground cluster of galaxies acts as a natural “zoom lens” in space by magnifying and stretching images of far more distant background galaxies.
By joining this natural lens with the resolving power of Hubble, scientists were able to see into the center of the dead galaxy.
The remote galaxy is three times as massive as the Milky Way but only half the size. Rotational velocity measurements made with the European Southern Observatory’s Very Large Telescope (VLT) showed that the disk galaxy is spinning more than twice as fast as the Milky Way.
Using archival data from the Cluster Lensing And Supernova survey with Hubble (CLASH), Toft and his team were able to determine the stellar mass, star-formation rate, and the ages of the stars.
The Hubble Space Telescope is a project of international cooperation between NASA and ESA (European Space Agency). The Very Large Telescope is a telescope facility operated by the European Southern Observatory on Cerro Paranal in the Atacama Desert of Northern Chile.