The possible existence of the ninth planet of the solar system became known in January 2016. Planet X is associated with the tilt of the axis of rotation of the Sun, the destruction of the planetary system and the occurrence of cataclysms on Earth. At the same time, scientists have advanced in understanding the role of this celestial body in the solar system, modeled its internal structure and proposed hypotheses explaining the origin of Planet X. "Lenta.ru" tells about the latest research.
The possible discovery of Planet X outside Pluto's orbit was reported by astronomers Mike Brown and Konstantin Batygin of the California Institute of Technology in Pasadena (USA). The probable ninth planet of the solar system is about ten times heavier than the Earth and revolves around the star in an elongated orbit (and in a plane inclined relative to the Earth's orbit) with a period of 15 thousand years. In terms of its physical and chemical properties, it resembles the ice giants Uranus and Neptune. As Brown and Batygin believe, this space object 4.5 billion years ago was knocked out of the protoplanetary disk near the Sun.
The closest distance from it to the Sun is 200 astronomical units (this is seven times more than from the Sun to Neptune). The maximum distance of Planet X is estimated at 600-1200 astronomical units, which puts its orbit outside the Kuiper belt, in which Pluto is located. Brown and Batygin estimate the probability of error at 0.007 percent. Scientists discovered the new planet by analyzing the gravitational disturbance it exerts on other celestial bodies.
Physics and chemistry
Astronomers Esther Linder and Christoph Mordasini from the University of Bern (Switzerland) came to the following conclusions about the physicochemical properties of this celestial body. The radius is 3.7 times that of the Earth. The temperature of the atmosphere, consisting of hydrogen and helium, is minus 226 degrees Celsius. Under the gas envelope there is a layer of water ice with a temperature of minus 63 degrees Celsius. Even deeper - a thin layer of silicate mantle, under which an iron core is hidden. Its temperature is estimated at 3.4 thousand degrees Celsius. According to astronomers, Planet X emits about a thousand times more energy than it absorbs and is gradually cooling down. Scientists believe that Planet X is a smaller copy of the gas giants Uranus and Neptune.
Possible structure of Planet X
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Image: Esther Linder, Christoph Mordasini, Universität Bern
American astronomer colleagues believe that the color of Planet X is dark blue, darker than Neptune, which has a dark blue hue in the optical range, and Uranus with its light blue gaseous envelope. Since the temperatures on Planet X are extremely low, there is practically no methane gas in the atmosphere, unlike the gas envelope of Neptune. This compound, according to scientists, condenses and is located at the base of the planet's atmosphere or its clouds.
Visiting guest
If Brown and Batygin believe that Planet X was knocked out of a protoplanetary disk near the Sun, then their colleagues from Sweden and France think differently: a celestial body may be an exoplanet that the Sun has captured from a nearby star. In their work, the scientists considered a scenario according to which Planet X was captured by the Sun from another star in its birth cluster. The sun was located in a grouping of several thousand young stars, and planets moved between them at low speeds (about a kilometer per second).
Orbit of Planet X (marked in yellow)
Image: Caltech / R. Hurt (IPAC)
This requires the simultaneous fulfillment of three conditions. First, the capture of Planet X by the Sun should have occurred at a distance of about 150 astronomical units from it (to avoid disturbances from the Kuiper belt). Secondly, the exoplanet had to revolve around another star in a cluster at a great distance from it (from one hundred astronomical units). This would allow the Sun to overcome the impact on Planet X of its first star. The third condition is that after the capture of the exoplanet by the Sun, it is possible to reproduce the current dynamic configuration of the solar system. In the modeling carried out in the framework of the N-body problem, astronomers have shown that all three conditions can be satisfied.
Astronomers believe that the cluster phase lasts about one hundred million years, and this is quite enough for the distribution of massive and distant planets (like Neptune) among the heaviest stars. Similarly, you can explain the nature of many trans-Neptunian objects in the Kuiper belt - those that are located at a distance of 30 to 55 astronomical units from the Sun.
To clean up
Planet X, according to Spanish and British astronomers, is capable of disturbing the orbits of celestial bodies in the solar system and throwing them out of it. Scientists analyzed the influence of Planet X on the motion of six extreme objects beyond the orbit of Neptune, the semi-major axis of which exceeds 150 astronomical units, and the perihelion is 30 astronomical units.
Simulations have shown that the orbits of the dwarf planet Sedna and candidate 2012 VP113 will remain stable for the next several hundred million years. On the other hand, the trajectories of the trans-Neptunian objects 2004 VN112, 2007 TG422, and 2013 RF98 (these celestial bodies reach 100-300 kilometers in diameter) are unstable and, after several tens of millions of years, they can be thrown out of the Solar System by Planet X.
Also, the influence of Planet X, French and Brazilian astronomers explained the inclination of the Laplace plane of the solar system. Scientists examined the dynamics of the four giant planets - Jupiter, Saturn, Uranus and Neptune. Each of these celestial bodies affects the total angular momentum vector of the solar system, perpendicular to the Laplace plane. Astronomers have studied the impact of Planet X on the Sun and giant planets. It turned out that this effect explains the tilt of six degrees between the Laplace plane and the plane of the solar equator.
The analytical model describes the amount of tilt depending on mass, eccentricity (orbital elongation parameter), semi-major axis of the orbit of Planet X and characteristics of giants. A few days before the publication of this discovery, astronomer Elizabeth Bailey presented similar conclusions in collaboration with the discoverers of Planet X.
Sun motion model
Image: arXiv.org
Some scientists have also ventured into more daring hypotheses. Astrophysicists Daniel Whitmeier and John Mats of the United States have blamed Planet X for the mass extinction of animals on Earth every 27 million years. The theory is based on the fact that the orbit of Planet X's rotation around the Sun slowly tilts, and every 27 million years it crosses the Kuiper belt (located 30 to 55 AU from the Sun). This leads to gravitational disturbances, and Planet X pushes comets from the Kuiper belt into the interior of the solar system. They bombard the planets (including the Earth). As they approach the Sun, they disintegrate into fragments, making it difficult for sunlight to reach celestial bodies (including the Earth).
According to scientists, this scenario is the most acceptable for a cosmic explanation of the mass extinction of animals. Two other scenarios - the presence of a second star next to the Sun and vertical oscillations of the star as it rotates around the center of the galaxy, as the authors note, do not receive paleontological confirmation. For the first time, Whitmeier and Mats proposed their hypothesis in 1985. Their study was published by Nature and Time (with picture on the cover). According to the initial hypothesis of scientists, Planet X is one to five times heavier than Earth and located a hundred times farther from the Sun.
What's next
Astronomers Carlos and Raul de la Fuente Marcos believe that there are not one, but two super-Earths outside Pluto's orbit. The available data on the perihelion precession of Sedna, 148209, 2004 VN112, 2007 TG422, 2010 GB174, 2012 VP113 and 2013 RF98 are, according to the authors' work, a good explanation if we assume the presence of at least two giant celestial bodies, one of which may be a Planet X. Since 2014, Carlos and Raul de la Fuente Marcos have been talking about the possibility of existence outside Pluto of two super-Earths.
All conclusions about Planet X are based not on direct observations, but on the analysis of its impact on other celestial bodies and computer modeling data. According to astronomers, 20 days of observations at the Japanese Subaru Observatory in Hawaii (USA) are enough for the direct discovery of Planet X. Scientists hope to reserve time for this at the observatory. Then, according to Brown and Batygin, the existence of Planet X will be finally proven.
Andrey Borisov
