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| | CAB Home » Radio astronomy » News » Publications - Photon Dominated Chemistry in the Nucleus of M82: Detection of HOC+ in a Starburst Galaxy Publications Photon Dominated Chemistry in the Nucleus of M82: Detection of HOC+ in a Starburst Galaxy
Authors
Fuente, A.; García-Burillo, S.; Gerin, M.; Usero, A.; Teyssier, D.; Rizzo, J. R.
Abstract
The nucleus of M82 has been mapped in 3mm and 1mm lines of CN, HCN, C2H, c-C3H2, CH3C2H, HC3N and HOC+ using the IRAM 30m telescope. These species have been selected for constituting a good diagnostic of photon-dominated chemistry. We have measured [CN]/[HCN] ratios >= 5 in the inner 650 pc galaxy disk. Furthermore, we have detected the HOC+ 1-->0 line with an intensity similar to that of the H13CO+ 1-->0 line. This implies a [HCO+]/[HOC+] ratio of ~ 40. This low HCO+/HOC+ abundance ratio unambiguously shows that the chemistry of the molecular gas reservoir in the nucleus of M82 is determined by the intense interstellar UV flux (G0 ~ 104 in units of Habing field). Finally, the detection of the hydrocarbons c-C3H2 and CH3C2H in the nucleus of M82 suggests that a complex carbon chemistry is developing in this giant photo-dissociation region (PDR).
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