Extinction curve A _λ /N _H caused by dust grains along an LOS at z = 0 R _* (through Betelgeuse, left panel) and z = 500 R _* (through a background star, right panel) at different values of ﹩{S}_{\max }﹩ with a fixed ﹩{a}_{\max }=0.5\,\mu {\rm{m}}﹩ and f _high-J = 100%. The vertical line represents the visual extinction A _V at λ = 0.5448 μm.