  In the young stellar object (YSO) phase of their lives, massive stars drive
bi-polar molecular outflows. These outflows produce beautiful, often hourglass
shaped, cavities. The central star possesses a powerful stellar wind (v ~ 2000
km s^-1), and possibly a dense equatorial disk wind (v ~ 400 km s^-1), which
collide with the inner surface of the bi-polar cavity and produces hot (T ~
10^5 - 10^8 K) shocked plasma. A reverse shock is formed at the point where the
ram pressure between the preshock flow balances the thermal pressure of the
postshock flow and provides a site for the acceleration of non-thermal
particles to relativistic energies. Hydrodynamical models of the wind
interaction, coupled with calculations of the non-thermal energy spectrum, are
used to explore the observable synchrotron and gamma-ray emission from these
objects.
