A new study has found that a small, reddish star brushed past our Solar System roughly 70,000 years ago around the same time when humans migrated out of Africa.
Known as Scholz’s star, the red dwarf is a mere 9 percent of the Sun’s mass. It is named after the German astronomer who discovered it.
According to the study conducted by a team of astronomers from the University of Cambridge and the Complutense University of Madrid, Scholz’s star left some traces of the interstellar encounter by perturbing some comets in the outer Oort Cloud, a reservoir of trans-Neptunian objects which is located at the confines of the solar system.
Back in 2015, when a team of astronomers led by Professor Eric Mamajek of the University of Rochester in the US discovered that the star had passed us by, they assumed that it was unlikely for the Scholz’s Star to disturb any of the objects in the Oort Cloud to a significant degree. They assumed that the red dwarf star wouldn’t have had much of an effect on the Solar System.
But as per the new study findings, it isn’t the case at all. In fact, the researchers claim that the impact of the star’s visit 70,000 years ago can still be seen today. It has been found that Scholz’s Star influenced the trajectories of some Oort Cloud objects.
For the purpose of the study, the astronomers analyzed around 340 objects of the solar system with hyperbolic orbits. They then identified the movements of dozens of known Oort Cloud objects as having been influenced by the passage of Scholz´s star. The close fly-by of the star did not disturb all the hyperbolic objects of the solar system, but only those that were closest to it at that time.
“Using numerical simulations we have calculated the radiants or positions in the sky from which all these hyperbolic objects seem to come,” said Carlos de la Fuente Marcos, co-author of the study.
“In principle, one would expect those positions to be evenly distributed in the sky, particularly if these objects come from the Oort cloud; however, what we find is very different: a statistically significant accumulation of radiants,” Marcos added. “The pronounced over-density appears projected in the direction of the constellation of Gemini, which fits the close encounter with Scholz’s Star.”
The study result has been published in the journal Monthly Notices of the Royal Astronomical Society: Letters.