Explained: On a strange planet 336 light-years away, clues to our own Planet Nine

Written by Kabir Firaque, edited by Explained Desk | New Delhi |

December 13, 2020 8:12:54 am

Artist’s impression of exoplanet HD106906 b. Credit: ESA / Hubble

A strange exoplanet, orbiting a double star 336 light years away, has caught the interest of astronomers. The strange behavior of the planet, HD106906 b, provides clues to our mysterious Planet Nine, if it exists at all. HD106906 b and their behavior have been described in a study published in The Astronomical Journal 10th of December.

What is this exoplanet and what is Planet Nine?

HD106906 b is not a new discovery: it appears in archival images taken by the Hubble Space Telescope in 2004. But at the time, people did not recognize that the object is a planet. “It wasn’t until follow-up observations were taken in 2013 of the system using a different telescope (specifically the Magellan Telescopes in Chile) that people realized that it was actually a different planet,” said lead researcher Meiji. Nguyen of the University of California-Berkeley told The Indian Express via email. Using data on the object’s motion over 14 years, astronomers have accurately calculated its orbit and other key details.

Planet nine it is a distant and elusive planet in our own Solar System. Although it has yet to be found, it has been predicted by a number of studies over the past few years, and astronomers have described it as “hidden in plain sight.” If it exists, Planet Nine is 10 times more massive than Earth.

Why is Planet Nine believed to exist?

These predictions arise from the peculiar behavior and alignment of various objects in the Solar System. Astronomers believe that all of this is happening under the influence of Planet Nine. For example, in the outer reaches of the Solar System, beyond Neptune, there is a region called the Kuiper belt, populated by icy debris. Some of the objects in this region have been found to be lined up in very peculiar ways, and Planet Nine is likely responsible for this, according to a 2016 article by Konstantin Batygin and Michael Brown of the California University of Technology. .

Then, in 2018, astronomers reported the peculiar behavior of another object in the Solar System, called 2015 BP519. The object orbits our Sun, but at an extreme tilt (54 ° C) compared to the orbits of Earth and the other seven planets. The simulations showed that the influence of Planet Nine (if any) would explain this tilt. Without Planet Nine, the tilt would be inexplicable.

Why is the new exoplanet compared to Planet Nine?

Both planets (assuming Planet Nine is real) reside far away in their respective star systems. They both orbit their respective stars at an extreme tilt. And both are massive enough to influence the behavior of other objects in their respective regions.

All that said, HD106906 b presents a more extreme case in these regards. While Planet Nine is supposed to be 10 times more massive than Earth, HD106906 b is 11 times the mass of Jupiter. HD106906 b is unusually far from its host star pair, more than 730 times the distance the Earth is from the sun. That makes its orbit extremely long: 15,000 years. Its binary star is relatively young at 15 million years, compared to our Sun, which is 4.6 billion years old. 📣 Follow Express explained on Telegram

So what clues does it offer?

The authors of the new paper investigated how HD106906 b could have reached such a distance from its star and raised the question of whether something similar happened with Planet Nine. The exoplanet’s star is surrounded by a disk of debris. This outer disk, observations and calculations showed, is not in symmetry with the inner ring of a comet. What could have disturbed the symmetry? This is what the authors propose:

The planet formed near the binary star and was later ejected due to gravitational interactions with the star. This stirred the objects in the debris disk and altered their symmetry with the comet’s ring. But when the planet was kicked out, it normally should have been kicked out of the system entirely and turned into a red planet. But it still orbits the star, from very far away. To explain this, the researchers suggest that a passing star interacted with the exoplanet and kept it in place. Today, it orbits its star with an eccentricity of 21 ° compared to the rest of the planetary system.

Did Planet Nine also form this way?

In fact, a similar scenario has been proposed. Planet Nine, if it exists, was formed early in the Solar System. Interactions with our giant planets, like Jupiter or Saturn, drove it out of the inner Solar System. After that, the passing stars stabilized their orbit.

Can the location and orbit of Planet Nine be predicted with measurements?

In fact, it can, Nguyen said. Caltech’s Brown and Batygin, authors of the 2016 paper mentioned above, have made predictions about where they think Planet Nine is likely to be in the sky. “Of course, the main challenge is trying to find such an object, because not only will it be very far away, but it will also be incredibly weak … So it would be like trying to find a small black spot in the total darkness of the already black sky. night, ”Nguyen said.

As such, many scientists are using indirect methods to track the planet rather than directly detecting it in a telescope.

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