A comet is approaching the Earth, changing ideas about stellar systems

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Russian astronomer Gennady Borisov discovered it with a makeshift telescope

The comet's discoverer, Russian astronomer Gennady Borisov, told us how he managed to detect a celestial body and what contribution the discovery can make to the knowledge of other stellar systems. The first data confirm: there may be "analogues" of the Earth.

We will make a reservation right away: fortunately, landing is not planned for us: having reached perihelion, the comet, as if fulfilling some mysterious mission, will abruptly turn and fly away from us forever …

The honor of discovering the comet belongs to Gennady Borisov. He works in the Crimean branch of the Astronomical Scientific Center and, concurrently, is an engineer at the GAESh of Moscow State University (Sternberg State Astronomical Institute, Lomonosov Moscow State University). In his free time he makes his own telescopes, through which he observes and searches for comets.

2I / Borisov is already the second body from another stellar system (hence the designation 2I – the second interstellar, that is, "interstellar") that has flown to us over the past two years. Before him, in 2017, Oumuamua 1I flew in – an asteroid in shape resembling a huge cigar (it was discovered using the Pan-STARRS telescope). The asteroid was first mistaken for a comet, then, without ever looking at its tail, they decided that it was still a small planet that had flown to us from some alien galaxy.

Although there were those who suspected that Oumuamua was a ship of aliens! Actually, the name itself, taken from the Hawaiian language, means "pioneer scout."

And on our horizon a new “newcomer” appeared – a comet, which was first called C / 2019 Q4. Despite the fact that at first it resembled an ordinary comet, specialists were struck by its trajectory, which was very different from the trajectories of other objects of our solar system.

The calculation of the trajectory of motion showed that the comet moves along a hyperbole. This means that, flying past us at the nearest distance on December 28, 2019, it will leave the solar system forever. In honor of its discoverer, the first interstellar comet was renamed 2I / Borisov. Now, the eyes of astronomers around the world are riveted to her.

Researchers from the Jagiellonian University in Krakow have already clarified the diameter of its core (it is 450 meters), the albedo value is the degree of reflectivity of the comet (it is 0.04, this means that the celestial body almost does not reflect light), and they also made out in its coma cyan gas molecules.

American scientists from the NASA Goddard Space Flight Center also said their word. After spectroscopic observations, they found that the comet produces diatomic carbon and sublimates (that is, transfers from solid to gaseous, bypassing the liquid) about 1.13×10 to the 25th degree of liters of water per second.

According to the first preliminary observations, it turns out that it is very similar to the comets of our stellar system. According to this, the researchers conclude that the conditions for the formation of our solar system are not unique, and far beyond its borders there can be many other Earths …

Photo: nasa.gov

Hubble image of a comet

– Gennady Vladimirovich, what did you look for on August 30 in the sky? – I ask the question to the discoverer.

“Searched for what I always seek,” comets. By that time, I had already discovered 7 comets, and I continued the search program. Finding a new one was logical: not so long ago I built my new, more powerful telescope with a diameter of 65 cm (the former, also created by Borisov, had a diameter of 30 cm. – Auth.). On it, since March of this year, I managed to discover a couple of asteroids, rediscovered the comet, which was discovered 10 years ago, but after which it was lost.

“But they were objects from our solar system, and a new one …”

– Yes, my new "catch" was an interstellar comet. At first there was no clarity about her. He sent data about her to the Center for Small Planets, received confirmation from other astronomers who began to observe her. A little later they counted and saw that the object was flying in a hyperbolic orbit. This meant that he could not be an object of our solar system. Now the comet is approaching us and in December it will approach the nearest distance.

– Tell, when and how exactly did the discovery happen?

– At night, an hour before dawn on August 30, 2019, when my telescope was directed to the eastern region of the sky – to where the Sun rises.

In this direction, researchers do not like to look at large telescopes because of the mass of problems that arise with the picture. Indeed, in the eastern part of the sky before sunrise, atmospheric fluctuations are especially disturbing for the observer. But then in this area of ​​the sky there is less competition between professionals and amateurs, and the latter use it. And the fact that until recently, it was there that I found all my previous comets, told me that I was on the right track.

So, back to observation. I was on duty at the telescope all night. Now astronomers do not look through the telescope with their eyes, all the information goes to the CCD photodetector – this is a digital camera that "observed" me. In the morning I went to bed, and when I woke up, I took up the processing of pictures on a computer. And in the very last frame, I found my comet.

– On which side to wait for her?

– At the time of opening and until recently, she was in the Northern Hemisphere. A few days ago it crossed the ecliptic, that is, the plane in which the planets of our solar system rotate, and now it is gradually entering the Southern Hemisphere.

As the comet approaches, the comet will be better visible, and more observatories and scientists will join observations and research. However, it is already being watched with the help of large telescopes, for example, that located in Chile, or the Hubble Space Telescope. The latter has already transmitted the first photos of the comet to Earth. A coma (gas-dust plume) is clearly visible on it, but the nucleus is not yet visible.

“How close will your comet come to us?”

– The smallest distance between us will be 300 million kilometers, or 2 astronomical units. By the way, the distance from the comet to the Sun will also be at this moment.

– The luminary will not interfere with observations?

– No, the Sun will no longer interfere, the comet will change its vector by that time, and it will be very convenient to observe it.

– In the comet's body, cyan gas was detected. Is it in the comets of our solar system?

– Cyan is the most common gas for our comets. By the way, if the comet’s gas glow has a bluish tint – this is precisely due to cyan. Dust comets typically have yellow or brown tails.

– What determines the length of the tail?

– From the distance of the comet to the Sun, that is, from the degree of its heating.

– Why does the comet have such a low reflectivity – with a coefficient of 0.04?

– Almost all comets have a low albedo. This is due to the fact that they are all very dark, and when the volatile reflecting substances that make up the train leave them, a lump with a tarry dark surface remains. In particular, the surface of my comet was also reddish.

“How fast is she flying?”

– When I discovered it, the speed was 32 kilometers per second. With the passage of perihelion, its speed will increase to 45 km / s, and then, when it begins to move away from us to infinity, the speed will decrease again. The sun will not be able to stop it and capture it in its orbit.

– Asteroid Oumuamua, discovered in 2017, also flew along a hyperbole?

– Yes. At first, they tried to detect cometary activity. But then, when they saw that nothing was evaporating from it, they finally identified it as asteroids.

– How did you know that it has a cigar-like shape?

– Of course, no one saw it firsthand – it was determined only by photometry: since the brightness changed during the rotation of the object, it was understood by the degree of change in this brightness that the object had an elongated shape.

– Can you talk about the shape of your comet yet?

– It’s hard to say what she is. When it flies closer – we'll see.

“They said about Oumuamua that it was an alien ship,” he was given such a name for a reason. Theoretically, comets can be ships?

“Unlikely.” But we cannot be pessimists and hope that there is still life in space. That is, there is a probability, but very small.

“Will you go watch the comet on some large telescope as it passes perihelion?”

– The Astronomical Scientific Center in Chile has its own telescope – I want to arrange for me to be allocated at least half an hour to observe it remotely, via the Internet.

“What other secrets can she discover at a closer distance?”

– New data specifying the shape and size of the comet, the chemical composition of the substance. I hope that we will understand from them the features of the formation of other stellar systems.

See also: Published data from interstellar space obtained by the Voyager 2 probe

. (tagsToTranslate) Science (t) Fresh MK (t) Gas (t) MSU (t) Krymsk

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