Presentation #306.01 in the session “Exoplanets and Systems: Orbital Dynamics 1”.
The traditional definition of the habitable zone (HZ) is the range of distances from a star that includes an Earth-like planet where the climate is stable enough for water to be, and is therefore, habitable. We investigate the additional effects of orbit perturbations from neighboring planets and their implications for a planet’s habitability. We examine the degree of dynamical packing of possible inner planet perturbers to the HZ of Solar type and M stars and find that Solar type stars could host more perturbers than M stars and remain dynamically stable. Using systems with confirmed planets from the NASA Exoplanet Archive, we analyzed the dynamical spacing of nearest known planetary neighbors to confirmed HZ planets to estimate the effects perturbers would have on them. The Hill spacing found with systems that host a HZ planet are consistent with Gyr dynamical stability timescales, however 9 of these systems had planets residing in the inner 40% of their host star’s HZ and with nearest neighbors within 16 mutual Hill radii. We performed numerical simulations of known planets residing in systems K2-3 and GJ 3293 to estimate the magnitude and timescales of orbit perturbations to the HZ planets and the resulting change in received stellar flux. We analyze these results using Laplace-Lagrange secular theory, and find that these orbit perturbations are primarily secular in nature. We discuss implications for the prospects of planet habitability based on the potential secular nature of HZs around Solar type and M stars.