  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. We note that 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, that are also in
vertical hydrostatic equilibrium. The planet has 20, 100, or 1000~M$_\oplus$,
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 more distant planet. The surface brightness contrast between outer wall
and shadow for the 1000-M$_\oplus$ planet is 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 radiative heating and cooling are key to the appearance of
protostellar disks with embedded planets.
