Solid evidence of buckminsterfullerene found in interstellar space by Hubble Space Telescope, the carbon molecule colloquially known as “buckyballs,” in the bewildering quagmire, that is the gas between the stars.
Buckminsterfullerene with formula C60 is a type of fullerene. It has a cage-like fused-ring structure that resembles a soccer ball consisting of twenty hexagons and twelve pentagons. With a carbon atom having one π bond and two single bonds at each vertex of each polygon and one bond at each polygon edge.
Buckminsterfullerene (C60) naturally occurs here on Earth. But it was also found in a nebula in 2010. It was discovered in a star orbiting gas in 2012. Now we have the strongest signs yet that it’s floating in the interstellar medium-the sparse, tenuous gas between the stars.
“Our Hubble Space Telescope spectra, combined with previous ground-based observations, places the detection of interstellar [buckminsterfullerene] beyond a reasonable doubt,” the researchers wrote in their document.
Studying the interstellar medium directly is hard, as it is highly diffuse. But beyond that, we can see starlight shining. As this starlight travels through the interstellar medium, the composition of what it passes through changes slightly. Some wavelengths are absorbed by the gas.
Spectrograph divides the light that it detects into a spectrum, a bit like a prism. Then astronomers interpret this spectrum here on Earth, identifying the light signatures of the elements.
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There are spectral characteristics called diffuse interstellar bands identified as the interstellar medium’s absorption features. But because we don’t know much about the interstellar medium. For example, the conditions under which it forms-it gets quite tricky to identify the individual molecules within those bands.
According to a team of researchers led by physicist Martin Cordiner of NASA Goddard SFC, previous papers claimed detection of buckminsterfullerene bands, but none showed proof beyond a reasonable doubt. This is partly due to the interference generated by Earth’s atmosphere when using a terrestrial telescope.
So, the team switched to the Hubble Space Telescope in Earth’s orbit, which conveniently eliminates this interference. They observed 11 stars, obtaining ultra-high signal-to-noise spectra of seven stars which are substantially reddened by the interstellar medium, and four which are not.
These spectra were then studied at four wavelengths associated with buckminsterfullerene for absorption signals.
The team made credible detections for the reddened stars in three of the four wavelengths (the remaining wavelength was anticipated to return only a weak signal anyway) and none at all in the control stars. The strengths of the signals were also consistent with 2018 laboratory measurements.
This is the strongest evidence yet for buckminsterfullerene in the interstellar medium, the researchers said.
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It is a beautiful outcome. It tells us that in the ghostly spaces between the stars, the molecule can exist, although we still don’t understand where it was created or how it got there.
It also informs us that more massive molecules can be supported by the interstellar medium than we knew. Previously, the largest molecules definitively detected in the interstellar medium only had 3 atoms that were heavier than hydrogen, while 60 were found in buckyballs.
“The confirmation of interstellar [ buckminsterfullerene ] represents a breakthrough in our understanding of chemical complexity in the diffuse interstellar medium. Bringing a fresh understanding of the kinds of molecules that may be responsible for the remaining (unknown) diffuse interstellar bands,” the researchers wrote in their paper.
“Further high-sensitivity observations are recommended in order to better limit the strengths and profiles of the weaker buckminsterfullerene bands. Combined with additional laboratory and theoretical studies that may allow the use of buckminsterfullerene bands as interstellar physics and chemistry samples.”
The research paper was published in The Astrophysical Journal Letters. It was first published in April 2019.