2020ApJ...889..152I

We consider a hypothetical planet with the same mass m, radius R, angular momentum S, oblateness J₂, semimajor axis a, eccentricity e, inclination I, and obliquity ε of the Earth orbiting a main-sequence star with the same mass M_* and radius R_* of the Sun at a distance r_•≃1pc from a supermassive black hole in the center of the hosting galaxy with the same mass M_• of, say, M87*. We preliminarily investigate some dynamical consequences of its presence in the neighborhood of such a stellar system on the planet's possibility of sustaining complex life over time. In particular, we obtain general analytic expressions for the long-term rates of change, doubly averaged over both the planetary and the galactocentric orbital periods P_b and P_•, of e, I, ε, which are the main quantities directly linked to stellar insolation. We find that, for certain orbital configurations, the planet's perihelion distance q=a(1-e) may greatly shrink and even lead to, in some cases, an impact with the star. I may also notably change, with variations even of the order of tens of degrees. On the other hand, ε does not seem to be particularly affected, being shifted, at most, by ≃0○ / . 02 over 1 Myr. Our results strongly depend on the eccentricity e_• of the galactocentric motion.