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More support for Planet Nine

This illustration represents orbits of objects distant from the Kuiper Belt and the planet Nine. The orbits made in purple are mainly controlled by the gravity of Planet Nine and have a narrow orbital grouping. Green orbits, on the other hand, are strongly coupled to Neptune and have a wider orbital dispersion. The updated orbital calculations suggest that Planet Nine is a planet of about 5 Earth mass located in a slightly eccentric orbit with a period of about ten thousand years. Credit: James Tuttle Keane / Caltech

Corresponding to the three-year anniversary of their announcement suggesting the existence of a ninth planet in the solar system, Mike Brown of Caltech and Konstantin Batygin publish a pair of papers analyzing the evidence of the The existence of Planet Nine.

The documents offer new details about the suspected nature and location of the planet, which is the subject of intense international research since the 2016 announcement by Batygin and Brown.

The first, entitled "Orbital Clustering in the Remote Solar System", was published in The astronomical journal January 22nd. Planet Nine's hypothesis is based on evidence suggesting that the clustering of objects in the Kuiper Belt, a field of icy bodies beyond Neptune, is influenced by the gravitational tugs of an invisible planet. The question of whether this clustering actually exists or whether it is an artifact resulting from a bias in how and where objects of the Kuiper belt are observed is an open question.

To determine if the apparent clustering is at the origin of the observation bias, Brown and Batygin developed a method to quantify the bias in each individual observation, and then calculated the probability that the grouping would be parasitic. . They found that this probability is about one in 500.

"While this analysis does not say anything directly about whether Planet Nine is there, it does indicate that the hypothesis rests on a solid foundation," says Brown, professor of planetary astronomy Richard and Barbara Rosenberg.

The second article is entitled "The New Planet Hypothesis" and is a guest report to be published in the next issue of Physics reports. The document provides thousands of new computer models of the dynamic evolution of the remote solar system and offers an up-to-date overview of the nature of Planet Nine, including an estimate that it is smaller and closer to the sun than it is. it was previously thought. Based on the new models, Batygin and Brown, as well as Fred Adams and Juliette Becker (BS 2014) of the University of Michigan, concluded that Planet Nine had a mass about five times greater than Earth's and possessed a semi-major orbital axis neighbors 400 astronomical units (AU), making it smaller and closer to the sun than previously suspected – and potentially brighter. Each astronomical unit is equivalent to the distance between the center of the Earth and the center of the sun, about 149.6 million kilometers.

"With five land masses, Planet Nine will probably look a lot like a typical extrasolar super-Earth," says Batygin, assistant professor of planetary science and researcher Van Nuys Page. The super-lands are planets whose mass is greater than that of the Earth, but much lower than that of a gas giant. "This is the missing link in the solar system for planet formation, and over the past decade, extrasolar planetary surveys have revealed that planets of similar size are very common around other sun-like stars. Nine planet will be the closest thing we will find to a window on the properties of a typical planet of our galaxy ".

Batygin and Brown presented the first evidence that there could be a giant planet tracing a strange and very elongated orbit in the outer solar system on January 20, 2016. This June, Brown and Batygin gave more details, including observation constraints on location along its orbit.

Over the next two years, they developed theoretical models of the planet that explained other known phenomena, such as why certain objects in the Kuiper belt had an orbit perpendicular to the plane of the solar system. The resulting models reinforced their confidence in the existence of Planet Nine.

After the initial announcement, astronomers from around the world, including Brown and Batygin, began looking for evidence of watching the new planet. Although Brown and Batygin have always accepted the possibility that Planet Nine does not exist, they claim that the more they examine the orbital dynamics of the solar system, the stronger the evidence to support.

"My favorite feature of Planet Nine's hypothesis is that it's verifiable by observation," says Batygin. "The prospect of one day seeing real Planet Nine images is absolutely electrifying, and while finding Planet Nine's astronomy is a daunting task, I'm very optimistic that we will imagine it in the next 10 years. . "

Explore further:
The super-earth coming home for dinner

More information:
Konstantin Batygin et al, the hypothesis of the new planet, Physics reports (2019). DOI: 10.1016 / j.physrep.2019.01.009

Michael E. Brown et al. Orbital grouping in the remote solar system, The astronomical journal (2019). DOI: 10.3847 / 1538-3881 / aaf051

Journal reference:
Astronomical Journal

Provided by:
California Institute of Technology

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