with this approach is that the infall would have to be approximately spherically symmetric in order to stop the H II region breaking out in low density directions. In any accretion scenario, most of the infalling material will arrive on the disc rather than the star and a bipolar H II region would ensue with ionized lobes above and below the disc (Franco et al. 1989). It also neglects the effect of winds and outflows which are likely to push the inner radius of the infalling envelope some distance away from the star, again mostly likely in the polar directions.

Another picture was developed by Tan and McKee (2003) in which strong outflow rather than infall confines the H II region. They used an approximate X-wind outflow density distribution where the H II region propagates along the cavity along the axis. These models are basically X-wind jets with extra photo-ionisation. They predict ionized zones that are very narrow (few AU), whereas most high-mass radio jets are resolved across the minor axis ($\sim$ 50 AU) (Martí et al. 1999; Curiel et al. 2006). Jets from high-mass objects are also likely to be significantly ionized as they are launched. Low-mass jets are 