| Description |
The scientific motivation for this proposal is to trace
the evolution of dust grains in relation to changes of the physical,
dynamical and chemical properties of the interstellar medium.
This program will provide an
unprecedented view of the structure of the ISM at far-infrared
and submillimeter wavelengths and will enable us to investigate
the impact of dust grains on the ISM physical and chemical state.
The program will take full advantage of four unique characteristics of
SPIRE and PACS: brightness sensitivity, wavelength coverage, angular
resolution, and mapping efficiency. The brightness sensitivity is
essential to measure the faint infrared emission from the diffuse
regions. The spectrometers will provide the
necessary information to derive the physical properties of
the atomic and molecular gas and completely characterize dust
evolution. The angular resolution is critical for tracing the dominant
processes in grain evolution which takes place on all scales down to a
few arcseconds. The data statistics will allow us to probe the impact
of extreme physical conditions, e.g., high densities, intense vortices or
illumination, on the dust evolution.
Our goal is to build with Herschel a coherent database on interstellar
dust emission extending to much smaller angular scales
than the IRAS and DIRBE surveys and covering a wide range
of ISM physical conditions, from diffuse clouds to the sites of
star formation and protostars. The program is supported
by state-of-art modelling of the dust
emission and physical processes acting on dust as well as by on-going
laboratory measurements of the grains properties at far-infrared and
submillimeter wavelengths. The Herschel observations will benefit
from ground-based ancillary data (HI and CO) and from Spitzer
programs yielding a full description of
the spectral energy distribution of interstellar dust from the
near-infrared to the submillimeter. |
