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Paper: Constraints on Circumbinary Habitability
Volume: 496, Living Together: Planets, Host Stars and Binaries
Page: 405
Authors: Mason, P. A.; Zuluaga, J. I.; Zhilkin, A. G.; Bisikalo, D. V.; Cuartas-Restrepo, P. A.
Abstract: We summarize the Binary Habitability Mechanism (BHM), a number of characteristics, especially stellar tides, that promote life on planets orbiting binary stars. A model binary consisting of two solar mass stars in a circular orbit is presented, with a semi-major axis of 0.0125 au, corresponding to an orbital period of 11.4 days. The circumbinary habitable zone (HZ) is derived as a function of stellar age. To ease comparison with Sun-Earth interactions, we examine a hypothetical planet receiving the same insolation as the Earth at a = 1.47 au. This places the planet in the HZ just beyond the runaway-greenhouse limit and it is too close to be in the continuously habitable zone, as is Earth. We investigate star-star and binary-planet interactions and their impact on habitability. Rotational deceleration of the stars, due to their mutual tidal torquing, hastens the reduction of extreme UV (XUV) and stellar wind fluxes incident on the planet. We simulate stellar wind collisions and find that standing spiral shock fronts are produced, causing significant atmospheric erosion for close-in planets. However, within the circumbinary HZ the stellar wind is considerably less aggressive towards the planet's atmosphere. Habitability conditions on the Earth analog are discussed and found to be comparable to Earth or better.
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