Remote sensing of dust around young stars and in comets

4 Remote sensing of dust around young stars and in comets 

Observing emission spectra from protoplanetary disks and comets in the infrared is a difficult task from the ground. The Earth s atmosphere is largely opaque in the infrared with the exception of a few windows. The clearest window, and therefore the most frequently applied one, is centered around 10 pm. Luckily, this window covers just the wavelength range enabling us to investigate the so-called 10 pm 

There are two important intrinsic limitations of infrared spectroscopy for the study of cosmic dust which are discussed below. 

To make things even more complicated, species without detectable emission features, like metallic iron, iron sulfide, or amorphous carbon, can dominate the radiative transfer in protoplanetary disks and thereby set the temperature structure. However, the abundances and size distributions of such grains are extremely difficult to constrain. 

Reading the above, one might get a pessimistic view of the possibilities of remote sensing techniques to derive the composition of cosmic dust in protoplanetary disks. However, when the limitations of the techniques are properly considered, it is possible to derive a wealth of information. The above limitations force one 

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