December 2008

Formyl radical

The formyl radical (HCO) was detected in four molecular clouds as reported in 1976 by Snyder et al. It was observed toward the giant molecular clouds W3, W51, K3-50, and NGC 2024 (the Flame nebula). A follow-up study in 1985 reported observations of four additional lines beyond the single line of the original report. A 2002 paper by García-Burillo et al. found HCO to be widespread in the galaxy M82 (picture here), a starburst galaxy undergoing a massive amount of star formation. The HCO observations appear to show that the nucleus of M82 is an enormous photon-dominated region. The formyl radical was also observed in Comet IRAS-Araki-Alcock (1983d).

HCO is a precursor to formaldehyde (H2CO). One possible pathway to the formation of both HCO and H2CO is via addition of H to CO in icy grain mantles, though the energetics suggest that this may not be a very efficient reaction.

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