The stars may have appeared earlier than we thought

A team of scientists led by the University of Massachusetts (UMass Amherst) reported the discovery of very ancient galaxies that were actively producing stars about 1 billion years after the Big Bang(that is, about 13 billion years ago).

These galaxies have long been hard to spot because they are shrouded in cosmic dust. Dust "quenches" ordinary light, and because of this, such objects are almost invisible to telescopes that look in the visible range. But the dust heats up and begins to glow in the infrared and submillimetre ranges - there they were able to detect.

Scientists used two instruments to search for them:

• ALMA in Chile - it helps to see the dust emission,

• theJames Webb Space Telescope (JWST) - it sees well in the infrared.

They first found about 400 bright dust galaxies using ALMA data, and then used JWST to identify about 70 fainter candidates at the farthest distances. After further inspection, the team concluded that many of these objects are indeed from the very early Universe.

Why this is important: Such galaxies may be the "middle ground" between two already known groups:

• very bright young galaxies that appeared very early in the Universe,

• and ancient, massive, quiet galaxies that almost stopped producing stars later on.

If this idea is confirmed, it would mean that star formation began earlier than some models suggest, and the history of the early Universe would have to be refined.