Discover the star that came closer to us: it is called Scholz Star, a red dwarf of small tonnage accompanied by a brown dwarf. 70,000 years ago it has slipped straight in the outer part of the Oort Cloud, the shell of comets that represents the outer edge of the Solar System.
While Homo sapiens began to migrate from the African continent, a star flew over at low altitude in the Solar System. In an article published in Astrophysical Journal Letters a group of astronomers from the US, Europe, Chile and South Africa has, in fact, determined that about 70,000 years ago the so-called Scholz star, a faint star discovered only recently, was very probably transited through the Oort Cloud, the very remote spherical end of comets surrounding the solar system. No other star is known to have ever approached our system in this way, five times closer than it is currently the closest star, Proxima Centauri.
Credit: Michael Osadciw / University of Rochester
The stars who have visited nearby our Solar System are actually two. Researchers have analyzed the speed and trajectory of a binary system consisting of a small red dwarf, with a mass equivalent to about 8% of that of the Sun, and a companion brown dwarf even lighter, with a mass too small to melt hydrogen in the core and ignite as a real star. The formal designation of the star is J072003.20-084651.2 WISE, but it has been nicknamed Star Scholz to honor the German astronomer Ralf-Dieter Scholz that unveiled it in the late of 2013.
Its trajectory indicates that the star of Scholz, 70,000 years ago came to about 52,000 astronomical units away from us, that it is more or less 0.8 years light or 8 trillion kilometers. A stone’s throw away, in astronomical terms, whereas Proxima Centauri is 4.2 light years. Astronomers explain that in all probability, the star has passed through the outer part of the Oort Cloud, or of that region to the furthest reaches of the solar system in which you think placid crowded billions of comets are waiting for some kind of disturbance in the precipice throw towards the Sun’s gravity.
Eric Mamajek University of Rochester and Valentin D. Ivanov of ESO (European Southern Observatory), two authors of the research, are interested in the star because it seemed to be moving very slowly despite being relatively close, about 20 light years. “Most of the stars in this area show a tangential motion much bigger – says Mamajek. The low tangential motion and proximity left or assume that the star was heading directly toward the solar system, or perhaps who had had a ‘recent’ close encounter and now was moving away. The radial velocity measurements were more consistent with the second hypothesis, that it was moving away from the sun. So, we realized that he must have made a flyby not too long ago. ”
To estimate the trajectory of the star, astronomers needed two different evidence: the tangential velocity and radial velocity, which were obtained by Ivanov and employees through observations with spectrographs mounted on large telescopes Southern African Large Telescope (SALT), South Africa, and Magellan, at Las Campanas in Chile. From these data, it could be established that the star of Scholz is moving away from our Solar System after examining it closely about 70,000 years ago.