Contents of: VI/111/./abstract/SCABRIT_CAMFLOWS.abs

The following document lists the file abstract/SCABRIT_CAMFLOWS.abs from catalogue VI/111.
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SCIENTIFIC ABSTRACT:
We propose to investigate with ISOCAM the presence and properties of
extended mid-infrared emission associated with energetic bipolar
outflows and circumstellar dust halos around young stellar objects.

The first part of this proposal deals with bipolar molecular outflows. Recent
array maps in the H2 S(1)(1-0) line at 2.12 microns often reveal shock
emission regions along the flow axis, probably associated with a fast
protostellar jet entraining the molecular gas. We expect that shocks of
velocity greater than 60 km/s will have observable signatures in the ISOCAM
range in the form of [NeII] emission at 12.8microns, while the UV radiation
released in the shock front may excite a broad and faint halo of mid-infrared
emission from small, heated dust grains. Together with longer wavelength
information from SWS, LWS, and PHOT, the spatially resolved information
provided by ISOCAM observations of these signatures will yield important
constraints on true wind speeds, integrated mass-loss rates, and entrainment
processes in protostellar winds, all of which are necessary for assessing the
role of outflows in star formation and cloud evolution.

In the second part of this proposal, we focus on a selected sample of young
stellar objects in order to investigate their detailed geometry and emission
properties of the ISOCAM range. In particular we will
search for extended 3-11micron emission from faint halos of small transiently
heated dust particles. Such a component has been invoked recently to explain
the mid-infared excess of YSOs, although scattering by large particles and
non-spherical geometries offer other alternatives. Our ISOCAM
observations will provide stronger constraints that should help
develop coherent models of the circumstellar environment of these objects.

OBSERVATION SUMMARY:

Our sample of molecular flows concentrates on those with a well-defined
bipolar appearance, high radial velocities in CO lines, and/or evidence for
shock activity (e.g. H2 or SiO emission, temperature increase in CO).

In each flow, the high-velocity CO extent will be raster-mapped in two CVF
steps, one at the [NeII]12.8micron line and the other in the neighbouring
continuum. An independent estimate of line+continuum level will be obtained
with a deeper map in LW10 (8-15micron) for comparison with CVF maps.  A
large scale map will be obtained with 6'' pfov to detect extended emission,
and a smaller area covered with pfov 3'' to reveal bright small-scale structure
(e.g.  bow-shocks).

A ``strip'' map across one outflow lobe will also be made in LW2 (pfov
6''), to search for a faint halo of small dust grains extending beyond the
CO contours down to a level of 2.5e-2 mJy/arcsec2 (5 sigma). In B335
(autumn) or L1448 (spring) a larger map will be made in both LW2
and LW3 for comparison with PHOT 60 and 100micron maps (TPRAY_INFRABI
proposal).

Our sample of young stellar objects includes embedded objects in the rho
Oph cloud with indications from earlier photometric measurements of excess
10 microns infrared emission at scales >10" (autumn), or similar objects in
the Cha I cloud as well as intermediate luminosity YSOs with spectral
evidence for very small grain emission or with outflow (spring).

All objects are imaged with ISOCAM in LW5, LW6, LW7, LW8 (to discriminate
between scattered light and extended emission in the 7.7 and 11.3 bands),
with pfov and sensitivity level indicated in Tables 3 and 4.  In addition,
a subset of sources (GSS30-IRS1, S1, WL22, DoAr25, IRS44, rho Oph A /
HD259431, LkHa25, T32, T33A/B, T29, T41) will be mapped in SW2, SW6, and
SW7 to search for the presence of extended 3.3micron feature emission and
to sample the ice band. Finally, a fully sampled CVF spectrum image from
5.5 to 8.5 micron will be taken of Source 1 and GSS30 (autumn) or T32 and
HD259431 (spring).

 LINKED OBSERVATIONS
none

 FIXED TIME OBSERVATIONS
none

 CONCATENATION

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