JWST sees ancient dust, possibly from very old supernovae

Dust may not sound like the most exciting topics, but for some astronomers, it is. Researchers recently used the James Webb Space Telescope to detect dust from the early universe, which could have been produced by very old supernovas.

James Webb is a powerful tool because it allows researchers to detect very distant, and therefore very old, galaxies. Webb can be used not only to detect these early galaxies but also to take patterns from them, which can reveal how they formed by looking at the wavelengths of light they absorb. As part of the JWST Advanced Deep Extragalactic Survey or JADES, Webb’s NIRCam instrument captured this image of a region of the sky known as GOODS-South. In this image, researchers used Webb’s NIRSpec instrument to look at the shape of early galaxies like JADES-GS-z6.

This image shows the position of the galaxy JADES-GS-z6 in a region of the sky called GOODS-South, which was observed as part of the JWST Advanced Deep Extragalactic Survey, or JADES. ESA/Webb, NASA, ESA, CSA, B. Robertson (UC Santa Cruz), B. Johnson (Center for Astrophysics, Harvard & Smithsonian), S. Tacchella (University of Cambridge), M. Rieke (Univ. of Arizona), D. Eisenstein (Center for Astrophysics, Harvard & Smithsonian), A. Pagan (STScI)

Using a spectrograph, researchers found evidence of carbon-rich grains in dust clouds. This appears to be similar to what has been found in polycyclic aromatic hydrocarbons (PAHs), however, it would not be possible for these complex chemicals to have formed so early in nature.

This is difficult because the spectra can appear similar for different compounds. In this case, it may be that the small difference found by the researchers is very important: their spectrum was most prominent at 226.3 nanometers, while PAHs are usually most prominent at 217.5 nanometers. It’s a very small difference, but it may be due to the mixing of particles found in the dust.

“The slight change in the length of the absorption is very strong, indicating that we can see a different combination of grains, for example, graphite or diamond grains,” said the study’s lead author, Joris Witstok of the University of Cambridge. in a words. Witstok continued to explain that this mixture could be caused by the first supernovas or large stars called Wolf-Rayet star: “This can be re-created in the short term by Wolf-Rayet stars or supernova ejecta.”

Since starting work with Webb last year, astronomers have noticed that early galaxies appear to be more numerous and larger than anyone had predicted, which, along with evidence like this discovery, is leading them to rethink their assumptions about the early universe.

“This discovery shows that baby galaxies in the early Universe grew faster than we expected,” said researcher Renske Smit from Liverpool John Moores University. “Webb shows us the complexities of the first stars (and planets) that species have yet to describe.”

The research is published in a journal Nature.

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