Several years ago, a group of astrophysicists, mainly from the Institute for Research in Astrophysics and Planetology (IRAP) in Toulouse, thought they had identified ionized buckminsterfullerene for the first time. Today, another team firmly confirms its existence with Hubble.
An international team of astrophysicists led by Martin Cordiner of the Catholic University of America (USA) seems to have put an end to a question that astrochemists have been asking for decades by publishing an article in The Astrophysical Journal Letters and that one can read free access on arXiv. To understand what it’s all about, here are a few reminders.
In the early 1920s, astrophysicist Mary Lea Shane (born Heger, 1897-1983) had highlighted the presence of something quite particular in the spectrum of certain stars not corresponding to any atom, or molecule, known to the time. It was discovered later that these observations were not associated with stars but with the interstellar medium interposed between them and the telescopes on Earth. Heger had thus discovered the existence of what is today called interstellar diffuse bands (DIB).
The interest of the study of the interstellar medium (MI) has grown steadily over the decades because it was realized that it contained dense and cold molecular clouds with a rich and complex astrochemistry where future stars were born surrounded by a planetary procession. It is thus the place of an important stage leading from the Big Bang to the living for an exobiologist as well as a subject of research for chemists and astrochemists.
It was because they wanted to better understand MI that in 1985, Harry Kroto, Bob Curl and Rick Smalley managed to synthesize a large carbon molecule in the laboratory with the geometry of the regular icosahedron. This molecule would become famous: it is the buckminsterfullerene, with its formula C 60. Kroto named this new molecule as a tribute to the American architect Richard Buckminster Fuller, the creator of the geodesic domes. The existence of buckminsterfullerene molecules had actually been predicted in 1970 by a Japanese chemist, Eiji Osawa.
Having heard later of Richard Smalley’s and Robert Curl’s laser spectral work at Rice University in the United States, Osawa joined them in simulating these atmospheres in the laboratory and trying to detect the presence of molecules C 60. Their success was announced by an article in Nature in 1985 and it would be worth the Nobel Prize in Chemistry in 1996. Other carbon molecules shaped like a balloon or football, with a different number of carbon atoms greater than or smaller than 60, were discovered later. They are collectively referred to as “fullerene.”
However, two questions remained unresolved: did buckminsterfullerene and its variants, especially ionized ones, exist in MI? Could the interstellar diffuse bands (DIBs) associated with them be explained?
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