Infrared detection of aliphatic organics on a cometary nucleus

TL;DR

This study used infrared spectroscopy to detect aliphatic organic compounds on comet 67P's surface, revealing complex organics and linking cometary material to interstellar origins and solar system evolution.

Contribution

First infrared detection of aliphatic organics on a cometary nucleus, confirming complex organic presence and suggesting a connection to interstellar material.

Findings

Identification of aliphatic organic bands at 3.38, 3.42, and 3.47 microns.

Spectral similarity to other carbon-rich outer solar system objects.

Implications for cometary evolution and interstellar material linkages.

Abstract

The ESA Rosetta mission has acquired unprecedented measurements of comet 67/P-Churyumov-Gerasimenko (hereafter 67P) nucleus surface, whose composition, as determined by in situ and remote sensing instruments including VIRTIS (Visible, InfraRed and Thermal Imaging Spectrometer) appears to be made by an assemblage of ices, minerals, and organic material. We performed a refined analysis of infrared observations of the nucleus of comet 67P carried out by the VIRTIS-M hyperspectral imager. We found that the overall shape of the 67P infrared spectrum is similar to that of other carbon-rich outer solar system objects suggesting a possible genetic link with them. More importantly, we are also able to confirm the complex spectral structure of the wide 2.8-3.6 micron absorption feature populated by fainter bands. Among these, we unambiguously identified the presence of aliphatic organics by their ubiquitous 3.38, 3.42 and 3.47 micron bands. This novel infrared detection of aliphatic species on a cometary surface has strong implications for the evolutionary history of the primordial solar system and give evidence that comets provide an evolutionary link between interstellar material and solar system bodies.