US scientists say solar system experienced closest ever encounter with star that whizzed past at distance of a light year.
By the standards of outer space, it was the closest call yet recorded: a star that zoomed past our solar system 70,000 years ago at a distance of five trillion miles. An international team of astronomers said on Tuesday the dim star probably passed through the solar system's distant cloud of comets, known as the Oort Cloud. No other star is known to have ever approached our solar system this close – five times closer than the current closest star, Proxima Centauri, said the team of researchers from the US, Europe and South America.
Their study was published in the journal Astrophysical Journal Letters.
Analysis of the trajectory of this recently discovered star – known as a red dwarf and christened with the name Scholz's star after its discoverer – suggests it passed roughly 0.8 light years from our solar system. Astronomically speaking, that is close.
The star is now 20 light years away, said Eric Mamajek, from the University of Rochester in New York and lead author of the study.
Using spectrographs and large telescopes in South Africa and Chile, researchers were able to go back in time and reconstruct its trajectory by calculating its speed. They were also able to determine that it is now heading away from our solar system. Until now, the top candidate for the closest fly-by of a star to the solar system was the so-called "rogue star" HIP 85605. It was forecast to come close to our solar system in 240,000 to 470,000 years from now.
But Mamajek and his colleagues also demonstrated that the original distance to HIP 85605 was probably underestimated by a factor of ten.
This above diagram shows the scale of our Solar System. The scale bar is in astronomical units (AU), with each set distance beyond 1 AU representing 10 times the previous distance (logarithmic scaling). One AU is the distance from the Sun to the Earth, which is about 150 million kilometres. Neptune, the most distant planet from the Sun, is about 30 AU. The Solar System is considered to reach as far as the Oort Cloud, the source of long period comets. Note the position of Voyager 1, the most distant man-made spacecraft in space. Image credit: NASA
Credits: Telegraph CO UK
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