Exoplanet puzzles scientists. Why is she so far from her star

Exoplanet puzzles scientists. Why is she so far from her star

If we talk about the solar system, then the most distant planet will be Neptune. You can also cover the dwarf planet Pluto, the signal from which reaches the Earth only after 4.6 hours. But all this stuff, when compared with the performance of an amazing gas giant who does not fit into physical models.

In the constellation of the Southern Cross at a distance of 300 light-years from the solar system is the star HD 106906, around which an unusual gas giant rotates. The age of this young exoplanet is only 13 million years, which is 350 times less than the Earth index. This is a red-hot planet with an average temperature of 1500 ° C.

Exoplanet puzzles scientists. Why is she so far from her star

Graphic representation of the orbit HD 106906 b. For comparison, the orbit of Neptune is indicated.

HD 106906 b is 11 times more massive than Jupiter and more in radius. It was first noticed in 2013 using 6.5-meter Magellan telescopes. However, it was difficult to detect, because the distance from the native star reaches as much as 97 billion km! For comparison, we recall that the average distance of Neptune is 4.55 billion km, and that of Pluto - 7.4 billion km. How is it that the HD 106906 b is located at such a long distance? Here it is important to note two points. First, we are talking about the gas giant. Usually such objects outside the solar system are much closer to the star. Even in our comparisons, we used ice, not gas giants. Secondly, the planet puzzles scientists because it brazenly ignores the nebular hypothesis.

Exoplanet puzzles scientists. Why is she so far from her star

Photo HD 106906 b, obtained by the tool SPHERE

Recall that the nebular hypothesis is the generally accepted scheme of how the Solar System is formed and developed. It is often used as a certain standard in the study of other star systems. So the theory suggests that the protoplanetary disk is simply not capable of stretching to such huge sizes. Yes, and how the gas giant appeared? Where did the necessary material come from?

Some believe that this world originated in isolation and in front of us is not a part of the star system, but a binary system. That is, the gas giant was supposed to be a star, but did not gain the required amount of mass and hung in the status of the planet. But the problem is that this scheme does not fit into the estimated mass ratio. We are seeing a 140: 1 ratio instead of the required 10: 1.

There is an option with planetary migration, where HD 106906 b was originally formed near the star, but then just migrated. But this process should have left a remarkable mark in the circumstellar cloud. And he is not! It remains then to assume that the planet is in no way connected by gravity with a particular star. We see only an illusion created from our point of observation. It sounds convincing, only the probability of this scenario is only 0.01%.

Exoplanet puzzles scientists. Why is she so far from her star

Planet Outcast 2MASS J2126-8140

So it turns out that we have a strange star system in front of us, where a star in some surprising way keeps gravity away such a distant object. By the way, we presented the record holder by distance among the gas giants. But there is an exoplanet 2MASS J2126-8140, which is distant by 4500 a. e, and the duration of its orbital period covers 1 million years. But there are still disputes about it, because some consider this object a rogue planet (“Billions of orphans” wander the Milky Way).

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