DUST AND INFRARED EMISSION IN THE EXTREMELY METAL-DEFICIENT

> in this proposal, more time is being requested for tthuan.sbs_0335 following our observation of sbs 0335052 in the midinfrared range we propose here to extend the infrared coverage of this exceptional object. this is motivated by the fact that sbs 0335052, one of the most metaldeficient galaxy known, is much brighter in the infrared than expected from its starforming properties (a factor of 6 in the lw10 band and we extrapolate at least a factor of 3 for the full infrared range). furthermore, the spectrum appears to require contribution from pah emission, i.e. carbon dust, a very unexpected dust component in a low metallicity object. the observations we propose to perform here are twofold: a cvf scan on the 916 microns that will: assess the contribution of carbon based dust reveal the shape of the continuum and allow comparison to that observed in more metalrich objects reveal the presence of a deep silicate absorption, an expected feature if the excess infrared is due to embedded hii regions. pht measurements at 25, 50, 60, 100, 120, 160 and 200 mic. the aim is to characterize with high details the infrared output of sbs in order to determine the origin of the excess emission, the amount of dust that is already present in the galaxy and the exact amount of starformation generated energy that is released in the infrared. these observations would make of sbs 0335052 one of the best studied analog to primordial galaxies that are now being detected at high redshift. the possibility that even very young galaxies might efficiently hide a substantial fraction of their star formation, as sbs 0335052 appears to do, would have profound impacts on how we derive the star formation rate at high redshift. truncated!, Please see actual data for full text [truncated!, Please see actual data for full text]