Free Astronomy Magazine September-October 2021

SEPTEMBER-OCTOBER 2021 T he detection of the heavy metals iron (Fe) and nickel (Ni) in the fuzzy atmos- phere of a comet are illustrated in this image, which features the spectrum of light of C/2016 R2 (PANSTARRS) on the top left superimposed to a real image of the comet taken with the SPECULOOS telescope at ESO’s Paranal Observatory. Each white peak in the spectrum represents a different element, with those for iron and nickel indicated by blue and orange dashes, respectively. Spectra like these are possible thanks to the UVES instrument on ESO’s VLT, a high-resolu- tion spectrograph that spreads the line so much they can be individually identi- fied. In addition, UVES remains sensitive down to wavelengths of 300nm. Most of the important iron and nickel lines appear at wavelengths of around 350nm, meaning that the capabilities of UVES were essential in making this discovery. [ESO/L. Calçada, SPECULOOS Team/E. Jehin, Manfroid et al.] A new study by a Belgian team using data from the European Southern Obser- vatory’s Very Large Telescope (ESO’s VLT) has shown that iron and nickel exist in the atmospheres of comets throughout our Solar System, even those far from the Sun. A separate study by a Polish team, who also used ESO data, reported that nickel vapour is also present in the icy in- terstellar comet 2I/Borisov. This is the Heavy metal vapours unexpectedly found in comets by ESO - Bárbara Ferreira