Star flew close to the solar system 70000 years ago - VIDEO PDF Print E-mail
Wednesday, 24 June 2015 06:00

Astronomers were able to determine the closest known star flown past our solar system: dim star passed through the Oort cloud 70,000 years ago. A team of astronomers from the US, Europe, Chile and South Africa have come to the conclusion that about 70 000 years ago, the dim star, probably, has gone through a remote cloud comets Oort cloud. No known stars have not been coming to our solar system so close - five times closer than the nearest star, Proxima Centauri.

Trajectory stars implies that 70 000 years ago, it took about 52 000 a. e. (about 0.8 light-years, 8 trillion kilometers or 5 trillion miles). This astronomically close: our nearest neighboring star Proxima Centauri is 4.2 light years away. In fact, in their work, astronomers 98 percent expressed confidence that the star passed through the so-called "outer Oort cloud" - a hypothetical region on the border of the solar system, filled with trillions of comets kilometer in diameter or larger, which run on an elongated orbit around the Sun.

star originally attracted the attention of Professor Eric Mamadzheka during a conversation with Valentin Ivanov of the European Southern Observatory. star showed an unusual set of characteristics: despite the relatively close proximity ("only" 20 light-years away), it is quite slow moving on a tangent. However, the measurement of the radial velocity has shown that the star is moving almost directly from the solar system with a fairly high speed.

    "The majority of nearby stars show more movement tangentially - says Mamadzhek, Professor of Physics and Astronomy of the University of Rochester. - A small movement of the tangent and the proximity originally pointed to the fact that the star is likely to move in the direction of a close encounter with the solar system, or "recently" come close to the solar system and are now removed. Radial velocity measurements have shown that the star is moving away from the Sun, which led us to the idea of ​​a close approach in the past. "

In order to develop the trajectory of stars astronomers needed the two indicators, the tangential acceleration and the radial velocity. Together with colleagues Ivanov described the newly discovered star by measuring its range and radial velocity using the Doppler shift. The measurements were carried out on large telescopes in South Africa and Chile: SALT and Magellan telescope in Las Campanas Observatory.

After the scientists collected all the information, they found that the so-called formal star Scholz moved from our solar system, and traced her way back in time, to restore its position 70,000 years ago. It turned out that it was the star closest to our Sun.

Until now, the leading candidate for the closest approach to the star of the solar system was the so-called "rogue star» HIP 85605, which took place close to our system 240,000 - 470,000 years ago. Mamadzhek and his colleagues demonstrated that the original distance to HIP 85605 has been lowered by ten times. And it likely distance - about 200 light years - away from the star relegated the Oort cloud.

Together with former student at the University of Rochester Bahrenfeld Scott (now a student at Caltech) Mamadzhek model built 10,000 orbits of the stars, taking into account the position of the stars, distance, acceleration, gravitational field of the Milky Way galaxy and the statistical uncertainty in all these dimensions. Of these 10 000 models 98% showed that the star passed through the outer Oort cloud, but only one has shown that the star came from the inner Oort cloud, which scientists have come to associate "comet showers."

While a close flyby stars Scholz will likely have little impact on the Oort cloud, Mamadzhek indicates that "other dynamic offenders Oort cloud may be hiding among nearby stars." The recently launched satellite of the European Space Agency "Gaia" should be mapped and measured distances acceleration billion stars. With these "Gaia", astronomers will be able to say whether other stars could pass close to our solar system in the past or will be there in the distant future.

Currently star Scholz - a small and dim red dwarf star in the constellation Monoceros, 20 light-years away. Nevertheless, at the nearest point flyby solar system star Scholz will be 10 magnitude star - about 50 times less than the star, which can be seen with the naked eye in the night sky. However, it is magnetically active, and therefore may flicker and become thoUSAnds of times brighter. It is possible that the star Scholz was visible to the naked eye of our ancestors living 70,000 years ago, at the minutes or hours during the rare outbreaks. This star is also part of a binary system: a small red dwarf (with a mass of 8% of the Sun) and "brown dwarf" (with a mass of 6% of the Sun). Brown dwarfs are considered "failed stars": their weight is not enough to support the synthesis of hydrogen in the core, like a big star, but they are much more massive gas giants like Jupiter.

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