Most of the stars are part of multi star systems. Single stars like the sun are the exception rather then the norm.
our solar system does have another star, infact in a few million years its going to kill all of us, it's called nemesis,
`Nemesis', is the ominous name scientists came up with when they began speculating about the sinister space body in 1984. They couldn't have picked a better name: Nemesis is one of the worst enemies of life on earth. Our solar system is what Nemesis calls `home'. And the bad part is: home is where Nemesis is heading.
What Nemesis is? It's nothing less than our Sun's twin brother. Yes, that's right: a second Sun! In the cosmos, many stars come in pairs. And according to the Nemesis theory, our `star' -- the Sun -- is no exception.
But wait -- why then do we see only one Sun? Well, for one thing, Nemesis is REALLY far away at the moment. Nemesis orbits the Sun in a huge ellipse, with its furthest point a distance of three light years away. But once every 25 to 30 million years, Nemesis closes in on the Sun. It slams into the outer regions of our solar system: a place called the Oort Cloud, at a distance of about half a light year away from the Sun.
And that would mean trouble for us tiny earthlings. The gravitational pull of Sun #2 would cause mayhem in the belt of cosmic debris that makes up the Oort Cloud. Comets and meteorites would fling off in all directions, at unimaginable speeds. For many thousands of years, our solar system -- including Earth -- will be bombarded with comets. And we all know what happens to terrestrial life when someone starts gunning our planet with colossal pieces of space rock.
and yes , i know i didnt write this, i am to lazy to write this