On the Seasonal Flux and Temperature Variations on Circumbinary Planets

A circumbinary planet (CBP) experiences an extrasource of flux due to a second star inside its orbit, which introduces more variability on the insolation pattern on the surface of the CBP. We study the influences and the importance of this variability on the overall flux received by an Earthlike CBP and the expected surface temperatures on an Earthlike planet using an N-body integrator and a 1DLatitudinal Energy Balance Model. We compare the CBP flux patterns to the equivalent single-star case and point out the characteristics unique to the CBP. In general, a CBP flux pattern is affected by two cases: (1) where the secondary star's luminosity is similar to the primary's and (2) where the secondary star's luminosity is much smaller than the primary's. In addition, we evaluate the variation in flux over a few planet orbits and find that the flux variation peaks on a CBP orbiting a G-K (μ ≈ 0.33) spectral binary. Assuming earth atmospheric properties, we find that CBP's surface temperatures and temperature variations are similar to the equivalent single-star cases, in agreement with previous studies (May & Rauscher 2016, Haqq-Misra et al. 2019). CBPs are on average slightly warmer than the equivalent single-star cases, and case 1 typically induces higher temperatures than case 2 relative to the respective single-star equivalent.