Is our Sun part of a double-star system? It's not an idea students hear about in introductory astronomy courses, but there's some reason to believe the Sun has a brown dwarf companion, nicknamed the Nemesis Star.
Giant, cool quasi-stars are known as brown dwarfs; they may look like Jupiter but they are not gas giants.
Brown dwarfs are neither planets no stars; they are betwixt and between objects-less massive than a star to be able to ignite internal thermonuclear fusion, but too massive to fall within the International Astronomical Union's mealy definition of what a planet is (or isn't, depending on the current day of the week).
NASA-JPL's nifty WISE space telescope-short for Wide-Field Infrared Survey Explorer-should be able to spot Nemesis, if it exists, during its tenous remaining mission status.
Launched in 2009, the probe ran out-of-fuel just a few weeks ago. However, like the Eveready Battery bunny, it's still sending back deep-space data. WISE has discovered 19 comets, more than 33,500 asteroids including 120 near-Earth objects-so far. Astronomers are expecting lots more fun stuff in WISE's amazing post-mortem telemetry downloads. Will Nemesis be among WISE's remaining surprises? Time is running out.
The Nemesis Star theory was first proposed during the 1980s by American paleontologists Dave Raup and Jack Sepkoski with considerable work contributed by astrophysicist Richard A. Muller. The trio tried to explain cyclical mass extinctions here on Earth with the idea that a red dwarf star, located 1.5 light years away from us, was the culprit.
The Nemesis theory proposes that the Sun's unseen quasi-stellar companion periodically disturbs the Oort Cloud, in the outer reaches of the solar system to hurtle dinosaur-killing asteroids and comets Sunward. It may even indirectly affect climate change. If Nemesis doesn't quite capture the drama of it all for ya, how about the nickname a few researchers have called this hypothetical object-the Death Star, a nod the giant battlestation of the "Star Wars" sci-fi saga.