Search for NH$\mathsf{_3}$ ice in cold dust envelopes around YSOs

摘要: We present a study of the 3.1 micron absorption band, attributed to OH stretching mode water molecule in form solid ice, observed many protostellar lines sight by SWS instrument on board ISO. Using ice optical constants and Mie theory, we obtain reasonable fits peculiar band shapes twelve sources. The clearly show that some scattering effects arise this as grain sizes used calculations are order few tenths micron. In fit residuals, search for ν 1 3 vibrations ammonia which fall same spectral region, leading only upper limits NH content percents total these different sight. also discuss occurrence 3.47 μ m could be related formation an hydrate mantles. On assumption is due merely with help relevant laboratory experiments, represents therefore at most 5% abundance relative interstellar Finally, sheds light "3.1 m/6 column density paradox" obtained when comparing (stretching mode) 6 (bending mode). paradox resolved considering extinction regimes, affects whereas pure dominates m.