We develop a fully analytic model for this two-wind interaction, which shows that depending on the value of the dimensionless parameter lambda = F0 c0 / nw vw2, where c0 is the sound speed of the ionized gas, F0 is the ionizing photon flux impinging on the surface of the accretion disks, and nw vw2 is the specific momentum flux of the wind from theta1 C Ori, both "choked" subsonic (low lambda) solutions and "free" supersonic (high lambda) solutions can be found. We argue that for the case of theta1 C Ori, this second, supersonic regime is relevant.
For the supersonic regime, we find that both the properties of the exciting star (theta1 C Ori) and the size of the accretion disk that ejects the photoevaporated wind enter the solution only as a direct scaling of the size of the proplyd. The only physical parameter with a more complex effect on the problem is the orientation between the axis of the accretion disk and the direction to theta1 C Ori.
We finally use this analytic model to produce predicted emission measure maps (which are directly compared to the HST images of O'Dell & Weng 1994). A good qualitative agreement is found at least for some of the proplyds observed in the Orion Nebula.
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