From
ExtremeTech.com:
While we’re all waiting for The Force Awakens to hit theaters, the time is again ripe for speculating on the plausibility of the Star Wars universe. Science fiction loves crazy astronomy — think Pandora, Halo, or Tatooine. The home planet of Luke Skywalker orbits a double star. But what do we know about how plausible the astronomy of Star Wars might be? How do you get a planet that has two suns?
Binary star systems are common throughout the observable universe; of the stars nearest our sun, about half are part of binary systems. For a long time, we didn’t even know whether a binary star system would be stable enough to allow matter to accrete to planetary dimensions. In 2014, researchers used
gravitational microlensing to confirm that an exoplanet with the working name OGLE-2013-BLG-0341LBb orbits one star of a binary pair at a distance of some 3000 light-years from Earth.
This particular
exoplanet orbits cool, dim stars and is therefore probably too cold to be habitable. But if you stood on its surface at the right time, you would see an unmistakable resemblance to the Tatooine sky: two suns, one bright, one dim. It’s certainly proof of concept. And what if those stars were just a little warmer, a little brighter? These are conditions that are tantalizingly suggestive of a real-life inhabitable planet just like Tatooine, somewhere in the universe we occupy.
Artist's impression of a binary star system. (Credit: NASA)
Truth may be stranger than fiction, though. It turns out that many multiple-star systems are actually groups of three stars called ternary systems, where one star orbits at some distance around a binary-star pair. It’s suspected that if the outer star had a rocky, Earth-like planet, it might be relatively
more likely to harbor life because of the large Goldilocks zone created by the arrangement of the three parent stars.
An observer on the surface of a planet in such a system would experience varying night lengths and varying phases of daytime temperature and illumination, related to how many of their stars were in the sky at any given time: one, two, or all three. Or at least they would until the planet inevitably became tidally locked, which means that one side of the planet would face its star forever: a seared, uninhabitable afterscape. Nobody has yet confirmed life on other planets, which means that we don’t know whether it’s more or less likely to find life around a binary or ternary system, but a compelling case can be made for either.
Still more complex stellar systems have been observed. Earlier this year, a five-star system in Ursa Major was announced by researchers from the Open University. Two pairs of its five stars eclipse along our line of sight, consistent with the spin mechanics of a relatively stable system. Scientists believe that a planet in this system might only have one real night per year, since such an event would require all five of the stars to appear in conjunction. Here’s hoping there’s some sort of relationship between stellar radiation and the appearance of the Force in life forms on a given planet.
