Astronomers using the James Webb Telescope may have discovered some of the universe’s first stars, which may provide clues about how galaxies form. Using the James Webb Space Telescope (JWST) and a phenomenon first predicted by Albert Einstein, scientists have discovered an early star known as a Population III star in a distant star cluster called LAP1-B, 13 billion light-years from Earth. They published their results Oct. 27 in The Astrophysical Journal Letters.
Population III stars, also known as dark stars, are theorized to be some of the first stars to form after the Big Bang about 13.8 billion years ago. According to this theory, hydrogen and helium combined with dark matter to create a giant star with a million times the mass of the Sun and a billion times the brightness of our star.
you may like
For example, a star’s spectrum, which indicates its composition based on the light it absorbs and emits, has emission lines that suggest large amounts of high-energy photons, consistent with the predictions of Population III. The spectra also suggested that the stars were very large, each on the order of 100 solar masses, and that the stars’ masses met several theoretical calculations.
“If it really is Pop III, this is the first detection of these primitive stars,” Visbal told Live Science.
However, the research team points out that JWST may have seen population III stars before. For example, a peer-reviewed study in March 2024 suggests that the telescope discovered part of the galaxy GN-z11, which formed just 430 million years after the universe itself.
However, the new study claims that the detection of LAP1-B is the only one that fulfills three theoretical conditions for Population III stars. It formed in a low-metallic (hydrogen and helium) environment at temperatures suitable for host star formation. Stars form in low-mass clusters, with only a few very large stars. This cluster then satisfies the initial mass function, a mathematical condition about how the masses of stars were distributed within the population when they formed.
Visbal said JWST was essential for observations because it has a 6.5-meter (21-foot) mirror that allows it to capture faint objects that are incredibly far away. But what helped LAP1-B come into view was a phenomenon called gravitational lensing. This phenomenon occurs when a very massive object, such as a galaxy, bends space-time around it while the background object is in just the right position. When light from a distant background object passes through the “warp” created by the foreground object, the background light is distorted into a ring or arc. This phenomenon is sometimes called the Einstein ring because it confirms what Einstein suggested would happen more than a century ago.
In this case, LAP1-B became visible when a closer galaxy cluster called MACS J0416 passed in front of it and “lensed” LAP1-B’s light.
JWST has also made it possible to observe emission lines from stars. The emission line was initially emitted at ultraviolet wavelengths, but then expanded into infrared wavelengths as the universe expanded, Visbal said. JWST is optimized for infrared observations, allowing you to see stars.
Aside from the novelty of a star discovery, Visbal said LAP1-B helps show how galaxies evolved. Because Population III stars are expected to form within small dark matter structures that were also building blocks of larger galaxies, “these stars can tell us about the early stages of galaxy formation and evolution, such as how metals initially contaminate primordial hydrogen and helium gases.”
Source link
