Extinction law for our dust models assuming a _max = 1 μm (thick solid), a _max = 100 μm (thick dotted), and a _max = 1 cm (thick dashed). Diamonds represent the measured extinction law from Cardelli et al. (1989) and Indebetouw et al. (2005). The thin solid curve represents a model with a _max = 0.5 μm (not used in our modeling) that best reproduces the measured interstellar extinction law up to 2 μm, but falls short of it in the 5–8 μm regime. The a _max = 1 μm is better in that regime and we use it as a proxy for "interstellar dust" in our model.