What Would Happen if We Were About 1 pc Away from a Supermassive Black Hole?

Abstract

We consider a hypothetical planet with the same mass m , radius R , angular momentum S , oblateness J 2 , semimajor axis a , eccentricity e , inclination I , and obliquity ε of the Earth orbiting a main-sequence star with the same mass and radius of the Sun at a distance from a supermassive black hole in the center of the hosting galaxy with the same mass 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 and , 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 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 over 1 Myr. Our results strongly depend on the eccentricity of the galactocentric motion.