Using the Cooled Mid-Infrared Camera and Spectrometer (COMICS) on the Subaru Telescope, astronomers have detected an unidentified infrared emission band from comet 21P/Giacobini-Zinner (hereafter, comet 21P/G-Z) in addition to the thermal emissions from silicate and carbon grains. These unidentified infrared emissions are likely due to complex organic molecules, both aliphatic and aromatic hydrocarbons, contaminated by N- or O-atoms. Considering the properties of the dust and organic molecules, comet 21P/G-Z might have originated from the circumplanetary disk of a giant planet (like Jupiter or Saturn) where it was warmer than the typical comet-forming regions.
Source:
https://phys.org/news/2019-11-subaru-telescope-mid-infrared-emission-band.html