Monday, February 26

Has JWST found the first stars in the Universe at last? 2023

Astronomers call non-hydrogen and helium elements metals. Astronomers understand that. The cosmos began with the two lightest components. Over 99% of atoms in the universe are big bang relics. Astrophysical processes formed all other elements, including carbon, iron, and gold. Supernova explosions, white dwarf-neutron star mergers, and stellar core nuclear fusion.

The universe’s metal content has risen throughout time due to various cosmic occurrences. Because of this, we categorize stars by metal content in their spectra. Stars have metallicity. Astronomers classify stars by metallicity.

Young stars are more likely to have planetary systems. Population II stars lack metals. Red dwarf stars dominate their elder population. Large Population II stars perished, leaving white dwarfs and neutron stars. Population I stars originated from their residual clouds.

Population I stars like our Sun have the most metals.

The Milky Way and other galaxies have both sorts of stars. We’ve never seen a third population. Ancient Population III stars. The early stars in the cosmos had essentially no metals. Population III stars were creatures without heavy elements to boost density.

Blue hydrogen-helium stars hundreds of times heavier than our Sun. They lived brightly yet briefly. The great-grandmother stars that exploded, sending the first metals into space. They died before our Sun formed.

The limiting speed of light lets us glimpse more into the past as we explore further into the cosmos. Astronomers have searched faraway galaxies for these early stars. With the James Webb Space Telescope (JWST) operational, they can see faraway galaxies. A new investigation may have discovered Population III stars.

GN-z11’s spectral lines were examined by the team. With a redshift of z = 10.6, it is one of the most distant galaxies ever discovered. Most of the galaxy is likely Population II stars because it developed after the initial stars. Population III stars may have formed in the galaxy’s gas halo.

This halo area has a strong HeII?1640 line, which is released by heated helium. This heated intergalactic gas lacks dazzling metal lines. HeII seems to be heavily ionized hydrogen and helium gas.

GN-z11’s active galactic nuclei (AGN) may heat the halo area, however the gas’s estimated temperature and distance from the galaxy don’t suit the AGN hypothesis. Massive Population III stars might have ionized the area. Based on ionization, these stars would have been 500 times more massive than the Sun, in the hypothetical mass range of PopIII stars.

This study is persuasive but not conclusive. We need additional distant galaxies observations. The JWST is delivering them.

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