Star that ‘grazed’ solar system 70,000 years ago threw objects off course

21 Mar 2018

An illustration of what it might have been like to observe Scholz’s star in the night sky 70,000 years ago. Image: José A Peñas/SINC

A star that ‘grazed’ the solar system thousands of years ago caused significant disruption in the region, throwing hundreds of objects off course.

It can almost seem hard to imagine in the modern age but around 70,000 years ago, modern humans and Neanderthals would have looked into the sky and seen an incredible sight: a large, dim red star that wasn’t our own.

Research from 2015 showed that at this time, a star that would go on to be called Scholz’s star came within less than one light year of our own sun, entering the reservoir of trans-Neptunian objects on the fringe of our solar system known as the Oort cloud.

Future Human

Since then, the star has travelled back out into deep space and is now located approximately 20 light years away. During its visit to our neck of the cosmic neighbourhood, it caused quite a disturbance, as new research shows.

In a paper published to Monthly Notices of the Royal Astronomical Society, a team of astronomers from the Complutense University of Madrid and the University of Cambridge have analysed nearly 340 solar system objects with hyperbolic orbits, more often v-shaped rather than elliptical.

Marking the first time this research has been done, the international team found that the trajectories of some of them were influenced by the passage of Scholz’s star.

The period in which this star passed through the Oort cloud and its position during prehistory coincide with the data of the new investigation and that of the 2015 study by Prof Eric Mamajek and his team. However, the findings show it only affected those closest to it at the time.

An even closer shave

Pointing out an example, the asteroid ‘Oumuamua that continues to make headlines was not influenced by Scholz’s star, with recent research showing it to have likely come from a distant binary star system.

“In principle, one would expect those positions to be evenly distributed in the sky, particularly if these objects come from the Oort cloud,” said Carlos de la Fuente Marcos, who co-authored the paper.

“However, what we find is very different: a statistically significant accumulation of radiants. The pronounced over-density appears projected in the direction of the constellation of Gemini, which fits the close encounter with Scholz’s star.”

While not ruling out the possibility that the changed paths of the objects could be merely a coincidence, the team said it was highly unlikely.

Also, these new simulations suggest that Scholz’s star approached even more than the 0.6 light years that was pointed out in the 2015 study as the lower limit.

Colm Gorey was a senior journalist with Silicon Republic