Extrapolated midplane temperatures of millimeter-sized dust as a function of radius based on measurements for three disk systems (TW Hya and CY Tau have similar profiles and are subsolar mass stars; Andrews et al. 2016; Long et al. 2018). Also shown are current confirmed exoplanets with radius measured via primary transits. Planets are culled to show only those with radii between 1 and 4 R _⊕ and are plotted as a function of semimajor axis and referenced to the axis on the right (“Number of Planets”). The soot line and ice line are also shown, which have different locations depending on the system, but the majority of detected super-Earths and sub-Neptunes lie in the “reduced carbon-rich zone.”