Small dust grain mean opacities as a function of temperature for three grain sizes. Left: Rosseland mean. Right: Planck mean. In the left panel the often-used opacity of Bell & Lin (1994) is plotted for comparison, which is used by Lin & Youdin (2015), Pfeil & Klahr (2019) and many other works. Malygin et al. (2017) use the dust opacity model of Semenov et al. (2003), which is, however, very similar to that of Bell & Lin (1994) in this temperature range. Also for comparison, the top two curves in each panel show the mean opacity for the simple κ_λ = 3π/2ρ_sλ small-grain opacity model used by Fukuhara et al. (2021), for our value of the material density ρ_s = 1.48 g cm⁻³ (Simple) and their value of ρ_s = 1.00 g cm⁻³ (SimpleF).