Astronomers calculated the approximate trajectory of Borisov's comet and localized the point in the sky where it entered the solar system. Today the star systems Ross 573, GJ 4384 and HD 34327 claim the role of her homeland, scientists write in an article accepted for publication in the journal Astronomy & Astrophysics.
"Borisov's comet flew at a record low distance from Ross 573, but this does not necessarily mean that it was born inside this stellar system. On the other hand, random encounters of this kind occur only once every 120 million years, while it flew to the Sun approximately for a million years. This speaks in favor of the fact that the meeting of a comet and a star did not happen by chance, "the scientists write.
The first interstellar comet 2I / Borisov was discovered on August 30 last year by the Crimean astronomer Gennady Borisov. According to the current estimates of astronomers, in terms of its size and chemical composition, it is quite ordinary. Now it is moving at a speed of about 30 km / s.
In early December last year, it flew to the Sun at a minimum distance of 305 million kilometers, and then began to return to the interstellar medium. Unlike the first such object, the asteroid Oumuamua, astronomers discovered Borisov's comet even before it had time to approach the Earth and the Sun. This gave scientists time to prepare for its observations and detailed study using ground-based and space telescopes.
In addition to the size and chemical composition of 2I / Borisov, astronomers were also interested in where and when the comet entered the solar system. The answer to this question is simultaneously important both for studying the typical lifetimes of "interstellar" celestial bodies, and for assessing how often they penetrate into various stellar systems.
Home of the interstellar wanderer
Marco Micheli, a planetary scientist at the Roman Astrophysical Observatory in Rome (Italy), and his colleagues find out by analyzing data from various ground-based and orbiting telescopes at different phases of the 2I / Borisov approach to the Sun.
This information helped scientists calculate a relatively accurate trajectory of the comet's flight and localize on the night sky map the point with which it entered the solar system, with an accuracy of several hundredths of a degree. To do this, astronomers calculated how the attraction of all planets in the solar system influenced the movement of 2I / Borisov over the past three thousand years.
The results of these calculations were superimposed by Italian planetary scientists on a map of the vicinity of the solar system, which was made on the basis of observations of the orbital observatory Gaia. Thanks to this, Micheli and his colleagues were able to identify more than a dozen stars that were located in the path of Borisov's comet. Three of them - Ross 573, GJ 4384 and HD 34327 - became the most likely candidates for the role of the 2I / Borisov homeland.
As Micheli and his colleagues note, Ross 573 has the most chances in this regard, since Borisov's comet approached this star at a distance of only 14 thousand astronomical units, the average distance between the Earth and the Sun, before leaving this star system. On the scale of the Universe, this is very close, so astronomers believe that Borisov's comet could well have escaped from this system.
According to planetary scientists, this star - a small and rather cold red dwarf - is one of the closest neighbors of the Sun. It is located at a distance of about 60 light-years from the solar system, and so far astronomers have not found planets or other satellites.
On the one hand, scientists doubt that Borisov's comet could have penetrated into the vicinity of Ross 573 from the interstellar medium, but on the other, they cannot yet rule out the opposite. In this case, GJ 4384 and HD 34327 - two other relatively close stars - will become the most likely progenitors of 2I / Borisov. Micheli and his colleagues hope that subsequent observations and calculations will clarify this issue.