Scientist may have identified the signature of the complex molecules behind a 40-year astrophysical mystery
For more than 40 年, astrophysicists have puzzled over strange emissions from outer space in specific infrared bands.
Now a new laboratory study suggests a plausible answer: clouds of vibrating metallic Fullerenes, large soccer-ball-like molecules also known as Bucky Balls after American futurist and geodesic dome evangelist Buckminster Fuller.
Emissions of infrared light in the 3 to 20-micrometer wavelength known as unidentified infrared emissions, have been observed in many different cosmic contexts, but especially around star-forming regions such as planetary nebulae. Scientists are still debating what is generating the emissions: energized clouds of polycyclic aromatic hydrocarbons or mixed aromatic/aliphatic organic nanoparticles have been proposed as sources, but not confirmed.
相比之下, according to the authors of a new paper available on the online academic server Arxiv.org, some Fullerene molecules have been confirmed to produce infrared emissions in space, specifically, emissions found at 7.0, 8.5, 17.4, and 18.9-micrometer wavelengths within planetary nebulae.
In the new paper the researchers — who were led by Gao-Lei Hou at Xi’an Jiaotong University, in China — hoped to better understand the infrared signatures of more complex Fullerene molecules that could explain more emissions. They created an experiment in the laboratory to see if they could predict the unique spectra of Fullerenes containing cosmically abundant metals such as lithium, aluminum, magnesium, and sodium out in space.
The result was the first ever laboratory measurement of infrared spectra of metallic Fullerene molecules.
“The overall agreement between the theoretical and laboratory spectra,” the researchers write in the paper, “provides confidence that we can reliably predict the infrared spectra.”
Now that scientists have a better idea of what the pattern of infrared light a vibrating metallic Fullerene may look like, they can begin to look for those signatures in space to see if, and where, they might exist.
Exactly how such molecules form, and in what quantity remains a mystery for now, the researchers wrote, but “The forthcoming high resolution and high sensitivity data from the James Webb Space Telescope can provide better constraints on the environmental conditions of specific fullerene-metal complexes and their abundances