The AIU names the second interstellar visitor | Human world

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Image of 2I / Borisov acquired on September 24, 2019 by the project of virtual telescope / Gianluca Masi.

The International Astronomical Union (IAU) said this week (24 September) that the orbit of the second alleged interstellar visitor – initially designated C / 2019 T4 – is now sufficiently well known to suggest object is:

… unequivocal interstellar origin.

And so, they have now given this object – which is supposed to be a comet – a new name. His name is 2I / Borisov. The "I" means interstellar. The "2" means that it is the second object of this type known to astronomers. And, following a long-standing naming convention for comets, Borisov is the name of his discoverer.

The IAU said in a statement:

On August 30, 2019, amateur astronomer Gennady Borisov, from 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 …

2I / Borisov will get closer to the sun (will reach his perihelion) on December 7, 2019, while it will be 2 astronomical units [AU, or Earth-sun distances] from the sun and also 2 AU from the Earth. In December and January, it is expected that [the object] will be at its brightest in the southern sky. He will then start his trip to go, eventually [probably] leave the solar system forever …

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 10.4-meter Gran Telescopio Canarias located in the Canary Islands, has already obtained a spectrum of 2I / Borisov and found it resembling that of typical cometary rings. .

Why are astronomers convinced that this object is interstellar? The reason is its orbit, which they have been monitoring for quite a long time now and enough to know that – after the December sun – 2I / Borisov will head out again and (most likely) will not come back in our solar system. .

Astronomers describe the orbits as that of 2I / Borisov as hyperbolic. Since the mid-nineteenth century, astronomers have discovered weakly hyperbolic comets disturbed by the Oort cloud. They have discovered thousands of hyperbolic comets up to now. But, of all these comets, the IAU said:

… No one 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. Only two years after the discovery of the first interstellar object 1I / 'Oumuamua, this new discovery suggests that these objects may be numerous enough to offer a new way of examining processes in planetary systems beyond ours.

IAU also stated that astronomers were eagerly observing this object, which will be continuously observable for several months, a longer period than that of its predecessor, II / Oumuamua. They said:

Astronomers are optimistic about their chances of studying this rare guest in detail.

In conclusion: the first known interstellar visitor received the official name of Oumuamua, which means "scout". This one has a less romantic name and is a standard for future discoveries: 2I / Borisov.

Via IAU