Name of the new interstellar visitor: 2I / Borisov

A new object from interstellar space has been discovered in the solar system. It is only the second discovery of its kind. The object offers a tantalizing insight beyond the solar system and raises puzzling questions. He was baptized 2I / Borisov by the IAU.

On August 30, 2019, amateur astronomer Gennady Borisov of the MARGO Observatory, in Crimea, discovered an object resembling a comet. The object has a condensed coma, and more recently a short tail has been observed. Mr. Borisov made this discovery with a 0.65 meter telescope that he built himself.

After a week of observations by amateur and professional astronomers from around the world, the IAU Minor Planet Center was able to calculate a preliminary orbit suggesting that this object was interstellar – the only object of this type known to have crossed the solar system.

The orbit is now sufficiently known and the object is unequivocal of interstellar origin; he received his final designation as the second interstellar object, 2I. In this case, the IAU decided to follow the tradition of naming cometary objects according to their discoverers. The object was therefore named 2I / Borisov.

Of the thousands of comets discovered so far, none has an orbit as hyperbolic as that of 2I / Borisov. This conclusion is independently supported by the Solar System Dynamics group of NASA's JPL group. Coming just two years after the discovery of the first interstellar object 10 / Oumuamua, this new discovery suggests that these objects may be numerous enough to offer a new way of studying the processes in planetary systems beyond ours.

2I / Borisov will approach closest to the sun, his perihelion, on December 7, 2019, when it will be two astronomical units (AU) of the sun and 2 AU of the Earth. In December and January, we expect it to be as bright as possible in the southern sky. He will then start his journey to go and eventually leave the solar system forever.

Astronomers are eagerly observing this object, which will be continuously observable for several months, a longer period than that of its predecessor, Oumuamua, and astronomers are optimistic about their chances of studying this rare guest in detail.

It is difficult to estimate the size of the comets because the small comet nucleus is anchored in coma, but according to the observed luminosity, the diameter of 2I / Borisov seems to be of the order of a few kilometers . One of the largest telescopes in the world, the Gran Telescopio Canarias of 10.4 m, located in the Canary Islands, has already obtained a spectrum of 2I / Borisov and found it resembling that of cometary nuclei typical.

This new interstellar visitor raises intriguing questions: Why have interstellar objects not been discovered before? What is the expected rate of their appearance in the internal solar system? How do such objects compare to similar bodies in the solar system? Large telescopic surveys capable of regularly scanning large portions of the sky can help answer these and many other questions in the near future.

Provided by
International Astronomical Union