Cosmic buckyballs could be the source of mysterious infrared light

Scientists may have just found the source of some mysterious infrared glows detected emanating from stars and clouds of interstellar dust and gas.

These bands of unidentified infrared emission (UIE) have baffled scientists for decades; according to new theoretical work, at least some of these bands may be produced by highly ionized buckminsterfullerene, more commonly known as buckyballs.

“I am extremely honored to have played a role in the amazingly complex quantum chemical research undertaken by Dr. Sadjadi that led to these very exciting results,” said astrophysicist Quentin Parker of the University’s Space Research Laboratory. from Hong Kong.

“They first relate to theoretical proof that fullerene – carbon 60 – can survive very high levels of ionization, and now this work shows that the infrared emission signatures of these species perfectly match some of the characteristics of most significant unidentified infrared emission known. This should help reinvigorate 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 is found naturally in soot, the carbon residue left over from burning organic matter.

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

It’s unclear exactly how buckyballs achieve this, though recent research suggests that they (like quite a few other things) are forged by dying stars. Since they’ve been around, however, scientists have been fascinated by exploring its properties and what may be happening to it in the vast universe.

Previously, Parker and his colleague, astrophysicist Seyed Abdolreza Sadjadi, also from the Space Research Laboratory, showed that buckyballs can take a beating in the harsh conditions of space.

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

What this research did not cover was the changes that the level of ionization would cause to the light emitted by the buckyballs. Sadjadi, Parker and their colleagues Chih-Hao Hsia and Yong Zhang, both also affiliated with the Space Research Laboratory, set out to investigate.

They performed a series of quantum chemical calculations to determine the wavelengths in which these molecules could be seen.

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

The team found that the ionized buckyballs are capable of emitting mid-infrared light at some of the key wavelengths associated with EUI – at 11.21, 16.40 and 20-21 micrometres.

More pertinently still, the emission of buckyballs stripped of 1 to 6 electrons is very easily distinguished from the infrared emission of another type of carbonaceous molecule, the polycyclic aromatic hydrocarbons, or PAHs, which are associated with the band of 6, 2 micrometers.

Since PAHs are another carrier candidate for EIU, 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 research presents strong arguments for future observations in the mid-infrared wavelength range to help locate and identify UIE associated with ionized buckminsterfullerene.

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

“In this paper, we worked with two other leading astrophysicists and planetary scientists…to determine the molecular vibrational notes of a celestial symphony, i.e., the spectral characteristics that these ionized buckyballs would play/produce. We then chased them into space showing their notes. /signatures are easily distinguishable from PAHs.”

The research has been published in The Astrophysical Journal.

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