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View Full Version : Aromatic hydrocarbons, and hydrocarbon derivates in space



m1omg
2008-Apr-08, 01:03 PM
How abundant are aromatics (benzene,toluene,napthalene etc.) and hydrocarbon derivates (aldehydes,halogenderivates,carboxylic acids,sugars,fats,esters) in space?How many of them occur in interstellar gas and dust and how abundant they are?And are they present also in cometary and TNO ices?I would imagine that a piece of hydrocarbon ice billions of years bombarded by the UV radiation from the Sun would yeild many interesting spieces, but I don't know.

ngc3314
2008-Apr-08, 02:30 PM
How abundant are aromatics (benzene,toluene,napthalene etc.) and hydrocarbon derivates (aldehydes,halogenderivates,carboxylic acids,sugars,fats,esters) in space?How many of them occur in interstellar gas and dust and how abundant they are?And are they present also in cometary and TNO ices?I would imagine that a piece of hydrocarbon ice billions of years bombarded by the UV radiation from the Sun would yeild many interesting spieces, but I don't know.

Polycyclic aromatic hydrocarbons (PAHs), some quite large, show up in the mid-IR spectra of practically anything containing gas and dust - comet tails, nebulae, galaxies... (hence some astronomers' response with a large yawn when the ALH84001 meteorite press conference mentioned PAHs, although in that case the mass spectroscopy was a bit more interesting). Various species have similar enough spectra that assignment of which hydrocarbon goes with which spectral feature is sort of generic. These are often seen as in the gray area between large molecules and small grains as regards their interaction with radiation. Their IR emission features were long known as the Unidentified Infrared Bands (http://www.astrochem.org/UIR.html) (UIRs). This ISO spectrum (http://ssc.spitzer.caltech.edu/documents/compendium/ngc6946/ngc6946phot_labeled.gif) shows the PAH IR features on a galaxy-wide scale.