Organic Compounds in Stardust

Often given romantic qualities stardust is not a term that is used in astronomy but it is often used colloquially to describe amorphous matter surrounding stars.

A paper in Nature by Sun Kwok & Yong Zhang Mixed aromatic–aliphatic organic nanoparticles as carriers of unidentified infrared emission features

Abstract Unidentified infrared emission bands at wavelengths of 3–20 micrometres are widely observed in a range of environments in our Galaxy and in others. Some features have been identified as the stretching and bending modes of aromatic compounds, and are commonly attributed to polycyclic aromatic hydrocarbon molecules. The central argument supporting this attribution is that single-photon excitation of the molecule can account for the unidentified infrared emission features observed in ‘cirrus’ clouds in the diffuse interstellar medium. Of the more than 160 molecules identified in the circumstellar and interstellar environments, however, not one is a polycyclic aromatic hydrocarbon molecule. The detections of discrete and broad aliphatic spectral features suggest that the carrier of the unidentified infrared emission features cannot be a pure aromatic compound. Here we report an analysis of archival spectroscopic observations and demonstrate that the data are most consistent with the carriers being amorphous organic solids with a mixed aromatic–aliphatic structure. This structure is similar to that of the organic materials found in meteorites, as would be expected if the Solar System had inherited these organic materials from interstellar sources.

For those who can remember their organic chemistry, the researchers propose the structure of a molecule that would display the spectroscopic signature they identified.

Science 2.0 has more details on what the results mean.

Astronomers are reporting that organic compounds of unexpected complexity exist throughout the Universe – which mean they can be made naturally by stars.

Researchers write in Nature that an organic substance commonly found throughout the Universe contains a mixture of aromatic (ring-like) and aliphatic (chain-like) components, compounds so complex that their chemical structures resemble those of coal and petroleum.

Since coal and oil are remnants of ancient life, this type of organic matter was thought to arise only from living organisms but this new discovery suggests that complex organic compounds can be synthesized in space – even when no life forms are present….

Most interestingly, this organic star dust is similar in structure to complex organic compounds found in meteorites. Since meteorites are remnants of the early Solar System, the findings raise the possibility that stars enriched the early Solar System with organic compounds. The early Earth was subjected to severe bombardments by comets and asteroids, which potentially could have carried organic star dust.

Obviously, this doesn’t answer the question of how life began on Earth aeons ago, however, it does propose another possible answer. One that doesn’t rely on supernatural sources.

For those who really appreciate the magic of Stardust, here’s Ella.

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2 Responses to Organic Compounds in Stardust

  1. Pingback: Bacteria and climate change | Innovation Toronto

  2. Pingback: » Carbon Dioxide Snatched From The Air

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