This work purports to model the far infrared gray-body emission in the spectra of high-Galactic-latitude clouds .
Several carbonaceous laboratory materials are tested for their fitness as carriers of this modified-black-body emission which , according to data delivered by the Planck satellite , and others before , is best fit with temperature 17.9 K and spectral index \beta =1.78 .
Some of these materials were discarded for insufficient emissivity , others for inadequate \beta .
By contrast , CHONS clusters ( \beta = 1.4 , T = 19 K ) combine nicely with magnesium silicate ( \beta = 2 , T = 18.7 K ) to give a spectrum which falls well within the observational error bars ( total emission cross-section at 250 { \mu } m : 8.6 10 ^ { -26 } cm ^ { 2 } per H atom ) .
Only 15 % of all Galactic carbon atoms are needed for this purpose .
The CHONS particles that were considered and described have a disordered ( amorphous ) structure but include a sizable fraction of aromatic rings , although they are much less graphitized than a-C : H/HAC .
They can be seen as one embodiment of “ astronomical graphite ” deduced earlier on from the then available astronomical observations .

Grain heating by H atom capture is proposed as a contributor to the observed residual emissions that do not follow the dust/HI correlation .