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In first image from the James Webb Space Telescope (Jwst) released by NASA there is much more than astrophysicists themselves could imagine: in the background there is a distant galaxy like never before. What appears to the uninitiated as a slightly smudged reddish dot is a light that dates back to 13.1 billion years agowhose emission spectrum (a sort of fingerprint of the galaxy) opens a small window on thePrimordial universe.
An unexpected discovery
On the James Webb Telescope there is a tool called NIRSpec which is able to detect the light coming from a galaxy in the telescope’s field of view, to isolate it and to analyze it to deduce its chemical signatures, namely the guy and the quantity from chemical elements that compose it.
What NASA experts have discovered by observing the light spectrum of that distant red galaxy portrayed in the first image of the JWST is the presence of the emission line of the ionized gaseous oxygen (at a wavelength of 436.3 nanometers). It is a landmark which, compared to the lines of other elements of the emission spectrum, allows us to understand different ones features of the galaxy: what is yours composition (how many metals, ie elements heavier than helium, there are actually), what is yours temperature, how many stars is forming.
As explained to New Scientist Andrew Bunker of the University of Oxford and a member of the NIRSpec team, looking for the emission line of the ionized gaseous oxygen in distant galaxies it was one of the objectives that they had proposed, but no one would have expected to find it in one of the first images transmitted by the Jwst. That was not the purpose of the image, and the discovery has so taken by surprise that it seems that the galaxy in question has never even been cataloged before.
A window on the evolution of the Universe
Knowing more about a 13.1 billion-year-old galaxy could help you get an idea of what the Universe must have looked like in the near future. big Bang, of which we know almost nothing. The Jwst can “see” back in time, finding more and more distant galaxies: the comparison of the emission spectra of different galaxies at that same epoch, which Jwst will be able to see, and of galaxies at different epochs, will allow us to reconstruct its evolution.
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