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==> In this proposal, more time is being requested for OBSID.PROPID
==> Time for this proposal is to be transferred from OBSID.PROPID
==> This proposal requests an upgrade from Priority 3 for OBSID.PROPID
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Bow shocks around runaway OB stars were discovered in the far infrared,
and they are bright an well defined at 60 microns. These structures
although apparently smooth at the IRAS low resolution, show a more complex
structure in HiRes maps. These features are intriguing in their nature and
they could be the result of dynamical or thermal instabilities.
In this proposal we want to map a section of Alpha Cam bow shock where
the intensity enhancements or ripples (instabilities?) are stronger and
more confined. The map will be performed at 60 microns with ISOPHOT in the
oversample raster mode (PHT32). Alpha Cam is specially suitable for this
experiment because the bow shock itself is bright (20-35 MJy/ster) and the
background contamination at 60 microns (5-15 MJy) is not overwhelming.
The goal is to distinguish the true morphology and structure of these
enhancements or ripples by observing a cross section of the bow shock.
The ISO resolution and sensitivity at 60 microns will permit to determine
their relative size and thickness. The length scales obtain will be used to
test both theory and numerical simulations of thin shell instabilities in bow
shocks around runaway stars.
The PHOT two legs raster scan should take a total time of 3035s.