By Leah Crane
NASA, ESA and D. Jewitt (UCLA)
The interstellar comet Borisov can be found in from the cold. Two sets of observations have actually revealed the composition of this weird comet, which may have formed in a cold, dark outstanding system.
Borisov was spotted in September, flying towards Earth on a trajectory that indicated it needs to have originated from another star. This was just the second interstellar object astronomers have definitively determined, and the very first interstellar comet.
As the comet reached its closest indicate Earth in December and January, passing just outside the orbit of Mars, astronomers around the world pointed their telescopes in its instructions in hopes of finding out more about its structure and where it came from.
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Martin Cordiner at NASA’s Goddard Space Flight Center in Maryland led a group that observed Borisov with the Hubble Space Telescope, and Dennis Bodewits at Auburn University in Alabama and his colleagues utilized the Atacama Big Millimeter/submillimeter Array (ALMA) in Chile to take a glimpse.
Both groups used their observations to evaluate the chemical composition of Borisov’s coma– the cloud of gas that forms around a comet as heat from a star warms it up. While a lot of comets in our planetary system have comas that are primarily water, Borisov’s seems mainly carbon monoxide.
” It was rather shocking to take a look at the data and see all this carbon monoxide,” states Cordiner. “This thing basically looks like a routine comet, however it has these different chemical signatures.” Those signatures indicate that Borisov formed in a stellar system that wasn’t quite like our own.
” Carbon monoxide ice vanishes very easily when you warm it, so we believe that Borisov formed in a system that was chillier than ours,” states Bodewits.
Journal references: Nature Astronomy, DOI: 10.1038/ s41550-020-1087 -2 and DOI: 10.1038/ s41550-020-1095 -2
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