where "m" is the mass of the candidate body in Earth masses, "a" is its semi-major axis in AU, "M" is the mass of the parent star in solar masses, and "k" is a constant chosen so that Π > 1 for a body that can clear its orbital zone. "k" depends on the extent of clearing desired and the time required to do so. Margot selected an extent of formula_4 times the Hill radius and a time limit of the parent star's lifetime on the main sequence (which is a function of the mass of the star). Then, in the mentioned units and a main-sequence lifetime of 10 billion years, k = 807. The body is a planet if Π > 1. The minimum mass necessary to clear the given orbit is given when Π = 1.