The following document lists the file abstract/OKUMURA_MC_DIFFU.abs
from catalogue VI/111.
A plain copy of the file
(without headers/trailers) may be downloaded.
We still do not know if PAHs (or other carbon dominated elements)
exist in environments as deficient in metal as in the case of the
SMC. From the ultraviolet observations, the SMC mean extinction
curve shows a very weak bump at 0.22 microns compared to the
galactic curve. The LMC curve is intermediate between the SMC and
Milky Way curves. This observational fact is thought to be related
to the underabundance of carbon in the interstellar dust in these
irregular galaxies compared to the solar neighborhood. From the
IRAS observations on the SMC one observes a very weak mid-infrared
(12 and 25 microns) emission. There seems to be a tight
correlation between the ratio nu*I(12 microns) to far-infrared
and the abundance O/H, which suggests that the weakness of the
12 microns emission is due to a metallicity effect.
The search of the PAH features in the Magellanic Clouds will
permit a more quantitative analysis in the frame of models
accounting for the underabundance of carbon in the dust grain
population.
The principal goals of this proposal are:
1) the detection of the near infrared features at 7.7 and 11.3
microns.
2) a sensitive photometry over a broad range of wavelengths to
constrain the models of grain population (composition and
size distribution).
3) measuring occasional contribution of line emissions in the far
infrared.
4) comparison between the far infrared emission and HI
distribution.