Cosmic Buckyballs Could Be Mysterious Infrared Light Source

Scientists may have just traced the source of some of the mysterious infrared emission detected from stars and clouds of interstellar dust and gas.

This Unknown Infrared Emission Band (UIE) has baffled scientists for decades; According to a new theoretical work, at least some of these bands could be produced by highly ionized buckminsterfullerene, better known as buckyballs.

“I am very honored to have played a part in the extremely complex quantum chemical investigations carried out by Dr Sadjadi that have produced these very exciting results,” said astrophysicist Quentin Parker of the Space Research Laboratory of the University of Hong Kong.

“First they looked at the theoretical evidence that Fullerenes – Carbon 60 – can withstand very high ionization rates, and now this work shows the infrared emission signature of the species is a perfect match for some of the most prominent Unknown Infrared Emission features known. This will help re-strengthen this area of ​​research.”

Buckminsterfullerene (C₆₀) is a molecule consisting of 60 carbon atoms arranged in the shape of a soccer ball or football. Here on Earth, it can be found naturally in soot, the carbon residue left by the burning of organic matter.

In space, the molecule has only been detected positively recently: in 2010, it was detected in a nebula, in 2012, it was found in gas around stars, and in 2019, it was found in thin gas floating in the ’empty space between stars. -star.

It’s not clear exactly how the buckyballs got there, though recent research suggests they were (like some other things) forged by dying stars. However, because they are there, scientists are fascinated to investigate their properties, and what could happen to them in the vast universe.

Previously, Parker and his colleague, astrophysicist Seyed Abdolreza Sadjadi, also of the Laboratory for Space Research, showed that buckyballs can withstand the harsh conditions of outer space.

In particular, they can become highly ionized – the process of adding or removing electrons. Up to 26 electrons can be removed from the buckyball before collapsing.

What the study didn’t cover was the change the ionization level would have on the light emitted by the bucky ball. Sadjadi, Parker and their colleagues Chih-Hao Hsia and Yong Zhang, both also affiliated with the Laboratory for Space Research, set out to investigate.

They performed a series of quantum chemical calculations to determine the wavelengths at which these molecules might be visible.

Then, they compared their findings with infrared observations of six objects, including stars and nebulae. The results, the researchers say, are both interesting and provocative.

The team found that the ionized bucky bulb tends to emit mid-infrared light at several key wavelengths associated with the UIE – at 11.21, 16.40, and 20-21 micrometers.

More precisely, the emission of a bucky ball with 1 to 6 electrons released can be easily distinguished from the infrared emission of another type of carbon molecule, polycyclic aromatic hydrocarbons, or PAHs, associated with the 6.2 micrometer band.

Since PAHs are another candidate for UIE carriers, this means that not only are buckyballs a strong candidate, but they can be easily distinguished from other potential carriers.

The team believes that this study presents a strong case for future observations in the mid-infrared wavelength range to help track and identify UIEs associated with ionized buckminsterfullerene.

“In our first paper, we showed theoretically that highly ionized fullerenes can exist and survive in the harsh and chaotic environment of space. It’s like asking how much air you can push out of a soccer ball and the ball retains its shape,” Sadjadi said. . .

“In this paper we worked with two leading astrophysicists and other planetary scientists … to determine the tone of the molecular vibrations of the celestial symphony, i.e., the spectral features that these ionized bucky balls would play/produce. We then hunted them in space to demonstrate their tone. /signature is easy to distinguish from PAH.”

This research has been published in Astrophysics Journal.

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