Our sun was born with an 'evil twin' called Nemesis that kicked an asteroid at the Earth and wiped out the dinosaurs
Scientists believe Nemesis may have kicked an asteroid into Earth's orbit, which wiped out the dinosaurs
Our sun may have had an "evil twin" that played a pivotal role in the extinction of the dinosaurs, according to a new report.
Astronomers from the University of California and Harvard University believe that, at the time our sun was born 4.5 billion years ago, it had a companion star.
This twin, which has been dubbed Nemesis, may have been responsible for kicking an asteroid into Earth's orbit which wiped out the dinosaurs.
After committing this atrocious act, it most likely escaped and mixed with all the other stars in our region of the Milky Way galaxy, never to be seen again.
The astronomers claim that our sun is not unusual in having a sibling. Many stars have companions - including our nearest neighbour, Alpha Centauri, which is part of a triplet system.
In fact, the new research, based on a radio survey of a giant molecular cloud filled with recently formed stars in the constellation Perseus, suggests that all sun-like stars are born with at least one companion.
"We are saying, yes, there probably was a Nemesis, a long time ago," said co-author Steven Stahler, a research astronomer at the University of California, Berkeley.
"We ran a series of statistical models to see if we could account for the relative populations of young single stars and binaries of all separations in the Perseus molecular cloud.
"The only model that could reproduce the data was one in which all stars form initially as wide binaries. These systems then either shrink or break apart within a million years.
"We now believe that most stars, which are quite similar to our own sun, form as binaries. I think we have the strongest evidence to date for such an assertion."
For the purposes of the study, "wide" means that the two stars are separated by more than 500 astronomical units, or AU, where one astronomical unit is the average distance between the sun and Earth.
A wide binary companion to our sun would have been 17 times farther from the sun than its most distant planet today, Neptune.
This explains why, after lopping an asteroid at our planet, Nemesis drifted away to some distant region of the galaxy.
The study has been accepted for publication in the Monthly Notices of the Royal Astronomical Society .