Has JWST finally found the first stars in the univese?

In astronomy, components aside from hydrogen and helium are known as metals. Whereas which may make your high-school chemistry trainer cringe, it is smart for astronomers. The 2 lightest components had been the primary to seem within the universe.

They’re the atomic remnants of the large bang and make up greater than 99% of atoms within the universe. All the opposite components, from carbon to iron to gold, had been created by astrophysical processes. Issues like nuclear fusion in stellar cores, supernova explosions, and collisions of white dwarfs and neutron stars.

As a result of a majority of these astrophysical occasions have occurred all through the historical past of the universe, and proceed to occur, the fraction of metals within the universe has elevated over time. Due to this, one of many methods we categorize stars is by the quantity of metals we see of their spectra. It is referred to as the metallicity of a star. With metallicity, astronomers categorize stars into three broad populations.

Inhabitants I stars, like our sun, have the best quantity of metals. They’re typically the youngest stars, and those probably to have planetary methods. Inhabitants II stars have fewer metals. They’re an older inhabitants, so a majority of them are red dwarf stars. There have been loads of giant Inhabitants II stars up to now, however they’ve lengthy since died, leaving white dwarfs and neutron stars. The remnant clouds of those useless stars supplied the raw materials out of which Inhabitants I stars shaped.

Each of a majority of these stars have been noticed within the Milky Way and different galaxies. However there’s a third inhabitants we have by no means seen. Inhabitants III stars can be actually historical. They might have been the primary stars to seem within the universe, with nearly no metals in them. With out heavier components to extend their density, Inhabitants III stars will need to have been monsters.

Sensible blue hydrogen-helium stars a whole lot of instances extra large than our sun. They might have had very brilliant however very quick lives. The nice-grandmother stars that solid the primary metals into space with their violent, explosive demise. They had been all gone lengthy earlier than our sun shaped.

However because of the finite velocity of sunshine, the deeper we glance into the cosmos the additional into the previous we are able to see. So astronomers have studied a number of the most distant galaxies looking for proof of those first stars. Now that the James Webb House Telescope (JWST) is on-line, they’re getting an incredible view of extremely distant galaxies. And based on a current research, one staff might have discovered the primary glimpse of Inhabitants III stars.

The staff checked out spectral traces from a area close to a galaxy referred to as GN-z11. It is one of the distant galaxies ever noticed, with a redshift of about z = 10.6, that means that we see it at a time when the universe was solely 400 million years previous. That is nonetheless after the very first stars probably shaped, a lot of the galaxy is probably going comprised of Inhabitants II stars. However Inhabitants III stars would possibly nonetheless have been forming within the halo of fuel surrounding the galaxy.

The spectral lines from this halo area present a powerful HeIIλ1640 line, which is the kind of line emitted by helium when it is extraordinarily sizzling. Usually such a sizzling interstellar fuel could have brilliant traces from “metallic” components, however this area does not have that. So the HeII area seems to be a mixture of hydrogen and helium fuel that has been strongly ionized by…one thing.

One chance is that the halo area could possibly be heated by an active galactic nuclei (AGN) on the heart of GN-z11, however the estimated temperature of the halo fuel and its distance from the galaxy does not actually match the AGN mannequin. The opposite different is that the area was ionized by large Inhabitants III stars. Based mostly on the extent of ionization, these stars would have been about 500 instances extra large than the sun, which is within the hypothetical mass vary of PopIII stars.

This research is not sufficient to show the presence of Inhabitants III stars, however it’s a compelling argument. We’d like extra observations of those distant galaxies. And due to the JWST, we’re beginning to get them.

The findings are printed on the arXiv preprint server.