Who damage the outer solar system: the star-vtorzhenets or "ninth planet"?
In the far reaches of our solar system lies the mystery. For a long time astronomers thought that the eight planets revolve almost perfect circular orbits, because once formed in a swirling disk of dust and gas surrounding a young Sun. But in 2003, scientists discovered a strange thing: the dwarf planet Sedna has a strange orbit, changing the position of the two distances to Pluto to more than twenty distance to the sun. And she was not the only one. For years after that astronomers have found nearly two dozen distant icy objects orbiting strange oblong and tilted relative to the plane of the solar system.
To explain such oddities, scientists have suggested that perhaps these worlds - the scars violent past. Perhaps one day a star passed close to the youth of the solar system, and off course these worlds. Or distant ninth planet of its gravity has violated the order in our system.
The latter hypothesis gained weight over the past few years, making the first smell the dust, says Suzanne Pfaltsner, an astronomer at the Institute for Radio Astronomy them. Max Planck in Germany. Anomalies in the orbits of several small objects of the solar system have accumulated evidence that the "ninth planet" about 10 times larger than Earth by mass. Meanwhile, star vtorzhenets considered too unlikely - so far. Pfaltsner and her colleagues recently published a paper on the arXiv preprint server, which was adopted by The Astrophysical Journal, which showed that the stars can fly close to our solar system is much more common than thought. These results not only give weight stellar theory of flight, but also may explain how the "ninth planet" in general was on his strange orbit.
A strange orbit of Sedna
Astronomers know that the sun has not always been so alone. It was born in a cluster of hundreds or tens of thousands of stars that are scattered throughout the galaxy in just 10 million years. Therefore, while our Sun was in this cluster, the stars were scurrying back and forth in a dizzying dance, which could easily lead to the aerial in our nascent solar system. But after the break in the accumulation of the probability of such an invasion has fallen almost to zero. Anyway, so we thought. But Pfaltsner and her colleagues now claim that the chances of invasion remained relatively high after the congestion began to crumble. After prolonged plurality of computer simulations, they found that the star mass with our sun with a probability of 20-30% could fly at 50 - 150 a. e Pluto. (1 and e -.. is the distance from the earth to the sun, about 150 million kilometers). Certainly, such an approach would close shook our young solar system.
Although large planet would remain intact (the Sun, for example, almost does not feel weak gravity of eight planets), the invasion could push apart small objects by putting them on a strange orbit on the solar system. Moreover, modeling and re-created the second trend, which astronomers have seen in the solar system - the tendency of external objects grouped. They move together in tight groups. In simple words, the star-vtorzhenets fits perfectly into the model, created on the basis of observations. "But if they hold on for 4, 5 billion years old," that is, as long as the solar system, "is the million dollar question," says Scott Kenyon, an astronomer at the Harvard-Smithsonian Center for Astrophysics, who was not involved in the study. And Pfaltsner agree with him. She would like to simulate the long-term behavior, to see if the changes persist, caused by the invasion of the star, during the whole period of existence of our system.
Scientists are eagerly looking for new data by using a number of different observational campaigns. Several teams, for example, is already scouring the large chunks of the sky in search of oddities in the outer solar system. Scott Sheppard, an astronomer at the Carnegie Institute of Science, who was not involved in the study, could not contain his excitement on the eve of launch of the Large Synoptic Telescope - 8, 4-meter dish, which will open hundreds of new solar systems.
Kenyon, meanwhile, hopes that the Gaia spacecraft, which is in the process of clarifying the provisions of a billion stars with unprecedented accuracy, helps you find the brothers and sisters of our star. This will allow scientists to better understand the star cluster in which our young solar system formed, as well as the likelihood that other star gets too close. "Gaia" - our new savior, "he says. A recent study by Gaia allowed to track the way nearby stars in the past and projecting them into the future, only to discover that the 25 stars can come dangerously close to our house for 10 million years. And, of course, everyone wants to find the "ninth planet". But Pfaltsner claims that the opening of another major member of the solar system does not rule out stellar span. "This is not a scenario either / or," she says. "If there is a ninth planet, it does not preclude a model of flight, rather it speaks in its favor." Predicted orbit ninth planet eccentric and inclined (relative to the plane of the solar system) could also be formed under the action of stellar span. The discovery of the ninth planet will put a lot of points of the i.