Some astronomers have hypothesized that a companion star that circles our sun that causes extinctions in the solar system may not exist. The idea was first proposed in 1984 to explain perplexing cycles in mass extinctions on Earth. About every 27 million years, almost like clockwork, there is a significantly higher likelihood that a mass extinction will take place on our planet (like an apocalypse that killed off the dinosaurs) about 65.5 million years ago.
The regular cycle of millions of years has been very troubling and confusing, and an element in our solar system causing the problem seems reasonable. The galaxy takes about 250 million years to orbit the center.
An ultra low-mass star such as a red or white dwarf might orbiting at a large distance, possibly a light year away. It would theoretically take 27 million years to finish an orbit. At that rate, once during each orbit it may enter a collection of comets surrounding the solar system called the Oort cloud. When the star passes through the Oort cloud, it could disturb the orbits of many comets, causing a shower of comets on Earth at such an extreme rate to cause such events.
A new study has confirmed that the 27-million-year cycle exists, with an excess of extinctions happening around those peaks. There are extinctions that occur in the middle of a cycle, and sometimes when a peak comes around the Earth has been safe. But, scientists confirmed that life gets a riskier here every 27 million years.