Neal Turner - February 6, 2018 Starlight Reshapes Planetary Nurseries Many protostellar disks show central cavities, rings or spiral arms likely caused by low-mass stellar or planetary companions, yet few such features are conclusively tied to bodies embedded in the disks. Even small features on the disk's surface cast shadows, because the starlight grazes the surface. We therefore focus on accurately computing the disk's thickness, which depends on its temperature. We present models with temperatures set by the balance between starlight heating and radiative cooling, and that are in vertical hydrostatic equilibrium. The planet has 20, 100, or 1000 Earth masses, ranging from barely enough to perturb the disk significantly, to clearing a deep tidal gap. The hydrostatic balance strikingly alters the model disk's appearance. The planet-carved gap's outer wall puffs up under starlight heating, throwing a shadow across the disk beyond. The shadow appears in scattered light as a dark ring that could be mistaken for a gap opened by another planet. The surface brightness contrast between outer wall and shadow for the 1000-Earth-mass planet is almost an order of magnitude greater than a model neglecting the temperature disturbances. The shadow is so deep it largely hides the planet-launched spiral wave's outer arm. Temperature gradients are such that outer low-mass planets undergoing orbital migration will converge within the shadow. Furthermore, the temperature perturbations affect the shape, size and contrast of features at millimeter and centimeter wavelengths. Thus, starlight heating and radiative cooling are key factors in the appearance of protostellar disks with embedded planets.