  The first indication of the presence of a circumstellar debris disk is
usually the detection of excess infrared emission from the population of small
dust grains orbiting the star. This dust is short-lived, requiring continual
replenishment, and indicating that the disk must be excited by an unseen
perturber. Previous theoretical studies have demonstrated that an eccentric
planet orbiting interior to the disk will stir the larger bodies in the belt
and produce dust via interparticle collisions. However, motivated by recent
observations, we explore another possible mechanism for heating a debris disk:
a stellar-mass perturber orbiting exterior to and inclined to the disk and
exciting the disk particles' eccentricities and inclinations via the
Kozai-Lidov mechanism. We explore the consequences of an exterior perturber on
the evolution of a debris disk using secular analysis and collisional N-body
simulations. We demonstrate that a Kozai-Lidov excited disk can generate a dust
disk via collisions and we compare the results of the Kozai-Lidov excited disk
with a simulated disk perturbed by an interior eccentric planet. Finally, we
propose two observational tests of a dust disk that can distinguish whether the
dust was produced by an exterior brown dwarf or stellar companion or an
interior eccentric planet.
