Monday, January 7, 2013

This is why you don`t want to live in a binary star system

Binary star systems sound cool and are featured in countless Sci-Fi stories and movies. But in almost half of all simulations the distant companion star ejected at least one of the gas giants, suggesting this would be a very common outcome in the millions of the galaxy's binary star systems.

Researcher Nathan Kaib of the University of Toronto explains:

"The stellar orbits of wide binaries are very sensitive to disturbances from other passing stars as well as the tidal field of the Milky Way. This causes their stellar orbits to constantly change their eccentricity – their degree of circularity. If a wide binary lasts long enough, it will eventually find itself with a very high orbital eccentricity at some point in its life. This process takes hundreds of millions of years if not billions of years to occur in these binaries. Consequently, planets in these systems initially form and evolve as if they orbited an isolated star. It is only much later that they begin to feel the effects of their companion star, which often times leads to disruption of the planetary system."


"We also found that there is substantial evidence that this process occurs regularly in known extrasolar planetary systems. Planets are believed to form on circular orbits, and they are only thought to attain highly eccentric orbits through powerful and/or violent perturbations. When we looked at the orbital eccentricities of planets that are known to reside in wide binaries, we found that they are statistically more eccentric than planets around isolated stars like our Sun. Recently, planets orbiting at wide distances around their host stars have been directly imaged. Our work predicts that such planets are common but have so far gone largely undetected."

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