High resolution 7 mm observations of the W49N massive star forming region have detected recombination line emission from the individual ultracompact ( UC ) HII regions on 50 milliarcsecond ( 600 AU ) scales .
These line observations , combined with multifrequency , high-resolution continuum imaging of the region at 7 mm ( VLA ) and at 3 mm and 1 mm ( BIMA ) , indicate that five to seven of the eighteen ultracompact sources in W49N are broad recombination line objects ( BRLOs ) as described by Jaffe & Martin-Pintado ( 1999 ) .
BRLOs have both broad radio recombination lines ( \Delta V > 60 km s ^ { -1 } ) and rising spectra ( S _ { \nu } \sim \nu ^ { \alpha } ) , with \alpha values greater than 0.4 .
The broad line widths of the H52 \alpha line are probably related to motions in the ionized gas rather than pressure broadening .
A number of models have been proposed to explain the long lifetime of UC HII regions , including the photoevaporated disk model proposed by Hollenbach et al .
( 1994 ) .
This model can also explain the broad lines , rising spectra and bipolar morphologies of some sources .
We suggest - based on line and continuum observations as well as source morphology - that in a subset of the W49N ultracompact sources we may be observing ionized winds that arise from circumstellar disks .