Precalculated emission spectra for spheres of optical depth radius for k ∈ {1,2,3,4,5}. The internal source of luminosity is neutral and isotropically radiating. It is placed in the center of the sphere and propagates through the sphere until it leaves it through its rim. The intensity I_SePS leaves the surface of the sphere and depends on the cosine of the penetration angle μ_s = cos(θ_s). The intensity is highest in the direction radially outward and overall decreases toward a smaller μ_s.