Interstellar Polycyclic Aromatic Hydrocarbons and Carbon in Interplanetary Dust Particles and Meteorites

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Science  03 Jul 1987:
Vol. 237, Issue 4810, pp. 56-59
DOI: 10.1126/science.237.4810.56


Both interplanetary dust particles (IDPs) and meteorites may contain material that is similar to polycyclic aromatic hydrocarbons(PAHs). The Raman spectra of IDPs and meteorites show features that are similar in position and relative strength to interstellar infrared emission features that have been attributed to vibrational transitions in free, molecular-sized PAHs. The Raman spectra of some IDPs also show red photoluminescence that is similar to the excess red emission seen in some astronomical objects and that has also been attributed to PAHs and hydrogenated amorphous carbon. Moreover, a part of the carbonaceous phase in IDPs and meteorites contains deuterium to hydrogen ratios that are greater than those for terrestrial samples. Deuterium enrichment is expected in small free PAHs that are exposed to ultraviolet radiation in the interstellar medium. Taken together, these observations suggest that some of the carbonaceous material in IDPs and meteorites may have been produced in circumstellar dust shells and only slightly modified in interstellar space.