An article published in the journal “Nature Astronomy” reports an initial characterization of interstellar comet 2I/Borisov, initially designated as C/2019 Q4. A team of researchers used data collected using the Gemini North on the island of Mauna Kea, in Hawaii, and the William Herschel Telescope in the Canaries. The data confirm it comes from another star system, yet it has characteristics very similar to the comets of the solar system.
Comet 2I/Borisov was discovered on August 30, 2019 by the amateur astronomer Gennady Borisov and after some observations the data about its orbit started suggesting its interstellar origin. After the first announcement of the discovery, new observations were carried out which confirmed that its trajectory is strongly hyperbolic and it has a remarkable speed. That’s proof that it comes from another star system because 2I/Borisov it’s far from the planets orbital plane so it can’t have suffered perturbations so remarkable as to cause that type of trajectory.
Two articles have already been published in the journal “Astrophysical Journal Letters” by two different teams: one to report the detection of cyanide gas emitted and the other to report the detection of carbon molecules emitted by 2I/Borisov. These are specific research focused on this comet’s emissions.
Another team led by astronomers Piotr Guzik and Michal Drahus of the Jagiellonian University in Krakow, Poland, conducted a more general work using two instruments: the Gemini Multi-Object Spectrograph for the Gemini North and Auxiliary-port Camera for the William Herschel Telescope. Their observations of comet 2I/Borisov indicate that it’s rather dark, with a reddish hue caused by the dust scattered in its extended coma and in its short tail. Its nucleus has a diameter of about one kilometer and this means that it’s small compared to the famous 67P/Churyumov–Gerasimenko, formed by two lobes 3-4 times longer each.
The comet 2I/Borisov is still approaching the Sun and in December 2019 it’s expected to reach its minimum distance, about twice that of the Earth from the Sun. The observations continue in various observatories to better understand its characteristics and verify similarities and possible differences with respect to the solar system’s comets.