in

Where is the missing Nemesis, our Sun’s sister star?

Credits: Flickr / Stefans02

The majority of stars in our solar system, like our Sun, are born with companion stars, or ‘twins’. So where is the missing “sister star” of our Sun? Could it even be influencing terrestrial life? 

Almost all of the large vertebrates on Earth went extinct 66 million years ago. We believe that an asteroid or comet of around 10 km in diameter was responsible for the catastrophe that led to this mass extinction. In the 1980s, Richard Muller, a physicist in Berkely University in California, presented the hypothesis that a twin star of our Sun – known as “Nemesis” – could have played a role in this accident, disrupting a comet belt in our solar system. Also note that the five great extinctions that have been known by Earth all occurred at regular intervals. Certain scientists thus believe that this regularity could be explained by abnormally raised levels of comet activity, which could be caused by the presence of another star close to our solar system.

A study carried out in 2017 by Berkely researchers effectively validated the idea, suggesting that almost all stars are formed in pairs. The researchers suggest that “all stars form initially as wide binaries. These systems then either shrink or break apart within a million years.” Therefore, our Sun could once have had a twin, before breaking off and going its own way. But this “sister star” – if it really exists – may not be too far away.

When Richard Muller presented his Nemesis theory, he suggested that the twin star could periodically cross the Oort cloud, a sphere of icy bodies situated well beyond Pluto. Many of these bodies travel around the Sun on very long elliptical orbits. Muller’s idea was that when these objects approach the distant star, they become dislodged from their course, sometimes taking on a new route leading them directly towards the Earth. If for example Nemesis traversed the Oort cloud every 27 million years, this could explain the five mass extinctions on Earth.

Although it is possible that our Sun was formed along with another star, on the other hand, many people do not support the idea that an “evil twin” star is still hiding somewhere nearby. Muller’s theory suggests that Nemesis could be situated around 1.5 light years from our Sun, but any attempts to localise it have failed. The Nemesis hypothesis has much evidence going against it. Regular passing of a massive object of this kind would in fact have left a clear imprint on the distribution of the craters on the moon, and on the dynamic structure of minor bodies in the solar system. And none of these signs have been observed.

Source

Related articles:

First images of a giant red star, 350 times larger than the sun

A star visited our solar system 70,000 years ago and it is still having effects

How the dinosaurs signed their death warrant ever before the asteroid that destroyed them