How the first stars and galaxies came into existence remains a fundamental pursuit in astronomy. Assisting us in this exploration, spanning an impressive 13.5 billion years, is the James Webb Space Telescope (JWST). With its unmatched ability to detect infrared radiation, the Webb telescope allows astronomers to compare the faintest, earliest galaxies with the magnificent spirals and elliptical galaxies we observe today. This invaluable instrument provides crucial insights into the gradual assembly of galaxies over billions of years.
A team of researchers recently made a remarkable discovery, leveraging the advanced capabilities of the telescope. The team was led by Professor Joaquin Vieira, an esteemed expert in astronomy and physics from the University of Illinois Urbana-Champaign. The study is a collaboration with graduate student Kedar Phadke and scientists from Texas A&M University and an international research group.
The goal was to distinguish between the infrared signals emitted by massive dust grains in the galaxy and those originating from the newly detected hydrocarbon molecules.
Professor Joaquin Vieira’s reflections on the project origins:
“This endeavour began during my time in graduate school. I was studying distant galaxies that are challenging to detect due to the obscuring effects of dust. Dust grains absorb and re-emit a significant portion of the stellar radiation in the universe. They render the infrared light from distant objects extremely faint or undetectable through ground-based telescopes.”
He explained that they were unable to observe or resolve the actual background galaxy due to the presence of dust. This was prior to gaining access to the combined power of gravitational lensing and the James Webb Space Telescope.
James Webb Space Telescope Reveals New Insights
Professor Vieira went on to elaborate on the significance of these findings:
“What this research is currently revealing, as we continue to learn, is that we can now observe all the regions where these smaller dust grains are located—regions that were previously invisible to us without the James Webb Space Telescope. The new spectroscopic data allows us to study the atomic and molecular composition of the galaxy. They offer crucial insights into galaxy formation, their life cycles, and how they evolve.”
By utilising the technique of gravitational lensing to magnify SPT0418-47, an object initially discovered with the National Foundation’s South Pole Telescope, the researchers were able to identify the presence of enriched heavy elements. This observation suggests that multiple generations of stars have already completed their life cycles of birth and death within that galaxy. Researchers have identified the specific compound as polycyclic aromatic hydrocarbon (PAH). It consists of carbon chains.
On Earth, these molecules commonly occur in the exhaust emissions of combustion engines or forest fires. The researchers note that these molecules serve as the fundamental building blocks for the earliest forms of life.
The Space Telescope Science Institute currently operates JWST, considered a giant leap forward in our quest to understand the Universe and our origins. The institution, operated by the Association of Universities for Research in Astronomy (AURA), manages JWST under the contract with NASA.
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