High-resolution images of the hypercompact HII regions ( HCHII ) in W3 IRS 5 taken with the Very Large Array ( VLA ) at 1.3 and 0.7 cm are presented .
Four HCHII regions were detected with sufficient signal-to-noise ratios to allow the determination of relevant parameters such as source position , size and flux density .
The sources are slightly extended in our \sim 0.2 ^ { \prime \prime } beams ; the deconvolved radii are less than 240 AU .
A comparison of our data with VLA images taken at epoch 1989.1 shows proper motions for sources IRS 5a and IRS 5f .
Between 1989.1 and 2002.5 , we find a proper motion of 210 mas at a position angle of 12 ^ { \circ } for IRS 5f and a proper motion of 190 mas at a position angle of 50 ^ { \circ } for IRS 5a .
At the assumed distance to W3 IRS 5 , 1.83 \pm 0.14 kpc , these offsets translate to proper motions of \sim 135 km s ^ { -1 } and \sim 122 km s ^ { -1 } respectively .
These sources are either shock ionized gas in an outflow or ionized gas ejected from high mass stars .
We find no change in the positions of IRS 5d1/d2 and IRS 5b ; and we show through a comparison with archival NICMOS 2.2 \mu m images that these two radio sources coincide with the infrared double constituting W3 IRS 5 .
These sources contain B or perhaps O stars .
The flux densities of the four sources have changed compared to the epoch 1989.1 results .
In our epoch 2002.5 data , none of the spectral indicies obtained from flux densities at 1.3 and 0.7 cm are consistent with optically thin free-free emission ; IRS 5d1/d2 shows the largest increase in flux density from 1.3 cm to 0.7 cm .
This may be an indication of free-free optical depth within an ionized wind , a photoevaporating disk , or an accretion flow .
It is less likely that this increase is caused by dust emission at 0.7 cm .