The research shines new light on the history of the comet – known as 31/ATLAS – as well its origins and composition.
A team of astronomers, led by the University of Edinburgh in partnership with the Universities of Liège, Belgium and Helsinki used the European Southern Observatory's Very Large Telescope (ESO's VLT) to study 31/ATLAS’s chemical makeup.
The findings indicate that the comet is around 12 billion years old and was formed outside of our own Solar System.
31/ATLAS
Interstellar comets are icy bodies that were formed outside our solar system and occasionally pass through our planetary system on an open trajectory before exiting back into deep space.
They are thought to hold material from the time when the Sun and our planets were forming.
3I/ATLAS is only the third interstellar comet ever discovered, after scientists discovered comets 1I/ʻOumuamua and 2I/Borisov in 2017 and 2019 respectively.
It was found as it was approaching the Sun, spending enough time in our Solar System for the team to study it in detail.
While it was difficult to measure the composition of the first two comets – in 1I/ʻOumuamua astronomers didn’t detect any gas and 2I/Borisov was too faint – this was not the case for 3I/ATLAS.
Brilliant radiance
Thanks to its unprecedented brightness, the team were able to measure the ratios of carbon and nitrogen isotopes found within the cyanide molecules present in the gas surrounding the comet.
These ratios are known to be good indicators of a comet’s origin, as they are sensitive to the physical conditions of the environment in which the comet was formed and are not expected to change much as the comet travels through space, experts say.
Related research
A similar study, led by NASA Goddard Space Flight Centre and published in Nature found a similar isotopic ratio of carbon, as well as elevated levels of deuterium, also called heavy hydrogen. The study used data from the James Webb Space Telescope (JWST) and was a joint project between the US, European and Canadian space agencies.
Cosmic findings
The current paper, published in Nature Astronomy, indicate that 3I/ATLAS likely formed around an old, low-metallicity star. This star is thought to have formed when the Universe was much younger and less chemically rich than it is now.
The team concluded that 3I/ATLAS therefore originated around a star much older than the Sun.