Observations of complex HII regions with known infrared sources
associated with them are proposed. These observations will be
carried out by using the LWS and the SWS instruments in their
high and medium resolution modes. Two regions in the Galactic
Plane have been chosen for detailed study, NGC6334 and NGC6357,
with the two high sensitivity ISO spectrometers.
After launch, ISO offers the only access to the wavelength regime
of interest for lines from OIII, NIII, NII, OI, CII, SI, SiII, SIII
SI, OH, CO, ammonia and water in the mid and far infrared.
These lines are ideal tools for probing visibly obscured regions.
LWS and SWS will also be used in their medium resolution grating
modes to obtain information about the spectral shape of the far
infrared contiuum from the dust in the sources and also to
determine which other lines are being emitted in the near and
far infrared by these sources.
LWS will be used to map areas centred on each of the selected
positions in both high and medium resolution modes while SWS
will be used to obtain data at, or very close to, the peaks of
the sources.
The SWS lines have been chosen principally to originate from high
electron density regions closer to the powering sources of the
objects while those monitored by the LWS arise further from the
source centre and closer to or into the molecular cloud.
Electron density, line flux and abundance variations maps will be
produced for each region and any structures within them should
become apparent i.e. shocked, density bounded or ionisation
bounded regions.