NASA’s James Webb Space Telescope prepares to deliver beautiful new images of distant galaxies. Still, it will also give us an unprecedented view of a small part of our atmosphere: the dust of space. One layer of dust can illuminate us with specific processes, such as how stars and galaxies form and change.

Very few of these dust particles are, technically, polycyclic aromas. They go by their first names, PAH (sounds like “pa” as in “grandfather slippers”), and they are one of the most versatile molecules in the universe. They include a whole family of large molecules with a chicken-like structure – hexagon latticework arranged in different patterns.

After its discovery in the 1980s, astronomers found PAHs almost everywhere they pointed their telescopes: in the gas clouds where stars formed, in some of the oldest galaxies, and – near home – in the Saturn moon, the Titan.

In the past, space dust was a problem for astronomers, as telescopes could not see through the dark clouds, hundreds of dust scattered across galaxies. With the advent of infrared astronomy, telescopes peeked through those hidden clouds, and we learned that atmospheric dust is essential to the formation of stars and planets. And Webb is ready to become a game-changer for unlocking its secrets.

“Webb has the power to shorten its earlier infrared telescopes and will revolutionize astronomy,” said Louis Allamandola, one of the pioneers in the field of PAH and a researcher at NASA’s Ames Research Center in Silicon Valley, California.

Unprecedented Data on Webb’s Dust Data

With the launch of Spitzer’s NASA telescope in 2003, with its next-generation infrared technology, PAH research began.

“Now, Webb will deliver an excellent spatial and spectral solution,” said Christiaan Boersma, an astronomer at Ames and chief investigator involved in a project that will use Webb to study PAHs in space. “We will be able to see the details – better details – on smaller scales than before. This will reveal how PAHs form and adapt to very different star locations. And that will allow us to unravel the photophysics and chemistry that guides the formation of stars and explain the remarkable diversity of objects we see, from exoplanets and stars to galaxies.”

Boersma is pleased with the detailed information spectra Webb will provide. These are similar to light fingerprints. When dust molecules are burned by the Sun or another star, they emit infrared light to cool. Light patterns, or spectra, can help identify the different types of PAH molecules the light emanates from them – if we can capture them well enough.

With low-resolution infrared telescope technology, astronomers have obtained a wide range of PAH or families. Determining the spectrum of a single type of PAH is possible. Still, it is a difficult task, requiring a combination of telescope detection, laboratory work, and an advanced computer under the Ames’ Laboratory Astrophysics team. The field was brought to maturity in Ames, allowing scientists to reconstruct laboratory conditions that form PAH interstellar space and measure spectral fingerprints of emerging molecules.

To date, they have impregnated about 100 “simple fingerprints” of about 100 different PAHs by studying laboratory molecules and 4,000 others with the help of computers. Armed with all that data, astronomers compare famous observations with PAH figures seen in the sky.

It is a huge undertaking, but researchers expect the powerful Webb telescope to develop a new way.

“The most important thing for us is to be able to identify and calculate – directly from telescope data – certain types of PAH that form the families we see,” Boersma said. “We are closer than ever, because of the important work that has been done before.”

With Webb optimization, they can amuse the sub-sets of PAH – defined by features such as size, shape, and electric charger – that contribute to visual effects. To analyze and explain PAH’s observations, researchers will turn to a research site developed by NASA scientists. The NASA Ames PAH IR Spectroscopic Database is free of charge to the global scientific community and provides comprehensive data libraries and tools.

“We are entering the ‘PAH research 2.0’ era,” Allamandola said. “Watching the spectrum is like listening to a symphony. Webb will allow us to hear all the different types of PAHs in the orchestra for the first time. That is a big step forward.”

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Alice is the Chief Editor with relevant experience of three years, Alice has founded Galaxy Reporters. She has a keen interest in the field of science. She is the pillar behind the in-depth coverages of Science news. She has written several papers and high-level documentation.


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