Is our solar system a Binary Star System? That is, having two stars, instead of one? Or is our solar system unique unlike every other star systems which are either binary or tertiary systems.

Every 26 million years, planet Earth witnesses a mass extinction. It is believed that this 26 million year cycle exterminated even the Dinosaurs!
Scientists thus explained the Nemesis Star Hypothesis.It could explain the occurrence of these mass extinctions in the geological scale.

The star Nemesis, is believed to be orbiting the Sun at a distance of about 95,000 AU (1.4 light years) behind the Oort Cloud which is an icy asteroid belt beyond Pluto.

Nemesis, otherwise known as the Sun's Evil Twin, is either a red dwarf or a brown dwarf, which on every 26 million years cause disturbance in the Oort cloud and sends asteroids towards Earth.

If the Nemesis hypothesis is true, then the earth may witness another mass extinction in the distant future, maybe of the whole mankind.