Let the mass of the star be 1.98e30 kilogram and the power be 8.52e27 Watt. The universal gravitational constant is 6.6726e-11 Nm^2/kg^2 and speed of light is 3e8 m/s. The density of the black particle is 1.85 g/cm^3. If the force due to the radiation pressure exactly cancels the force due to gravity, find what is the radius of this particle is micrometer.