A small sphere (emissivity = 0.90, radius = r1) is located at the center of a spherical asbestos shell (thickness = 1.0 cm, outer radius = r2). The thickness of the shell is small compared to the inner and outer radii of the shell. The temperature of the small sphere is 800.0 °C, while the temperature of the inner surface of the shell is 600.0 °C, both temperatures remaining constant. Assuming that r2/r1 = 10.0 and ignoring any air inside the shell, find the temperature of the outer surface of the shell.