Production of H$_3^+$ via photodissociation of organic molecules in interstellar clouds

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dc.creatorPilling, S.
dc.creatorAndrade, D. P. P.
dc.creatorNeves, R.
dc.creatorFerreira-Rodrigues, A. M.
dc.creatorSantos, A. C. F.
dc.creatorBoechat-Roberty, H. M.
dc.date2006-12-14
dc.date.accessioned2026-07-07T10:21:15Z
dc.date.available2026-07-07T10:21:15Z
dc.descriptionWe present experimental results obtained from photoionization and photodissociation processes of abundant interstellar CH$_3$-X type organic molecules like methanol (CH$_3$OH), methylamine (CH$_3$NH$_2$) and acetonitrile (CH$_3$CN) as alternative route for the production of H$_3^+$ in interstellar and star forming environments. The measurements were taken at the Brazilian Synchrotron Light Laboratory (LNLS), employing soft X-ray photons with energies between 200 and 310 eV and time of flight mass spectrometry. Mass spectra were obtained using the photoelectron-photoion coincidence techniques. Absolute averaged cross sections for H$_3^+$ production by soft X-rays were determined. We have found that, among the channels leading to molecular dissociation, the H$_3^+$ yield could reach values up to 0.7% for single photoionization process and up to 4% for process involving double photoionization. The H$_3^+$ photoproduction cross section due to the dissociation of the studied organic molecules by photons over the C1s edge (200-310 eV) were about 0.2-1.4 $\times$ 10$^{-18}$ cm$^2$. Adopting the typical X-ray luminosity $L_X \gtrsim 10^{31}$ erg s$^{-1}$ which best fit the observational data for AFGL 2591 (Stauber et al. 2005) we derive an estimative for the H$_3^+$ photoproduction rate due to methyl-compounds dissociation process. The highest value for the H$_3^+$ column density from methanol dissociation by soft X-rays, assuming a steady state scenario, was about $10^{11}$ cm$^2$, which gives the fraction of the photoproduced H$_3^+$ of about 0.05%, as in the case of dense molecular cloud AFGL 2591. Despite the extreme small value, this represent a new and alternative source of H$_3^+$ into dense molecular clouds and it is not been considered as yet in interstellar chemistry models.
dc.descriptionThe paper contains 7 pages, 3 figures and 3 tables. Accepted to be published on MNRAS on 2006 December 14. Received 2006 December 14; in original form 2006 September 19
dc.identifierhttps://arxiv.org/abs/astro-ph/0612402
dc.identifierhttp://arxiv.org/abs/astro-ph/0612402
dc.identifierMon.Not.Roy.Astron.Soc.375:1488-1494,2007
dc.identifierdoi:10.1111/j.1365-2966.2006.11415.x
dc.identifier.urihttp://salesiana.dossiersoluciones.com/handle/123456789/175110
dc.subjectAstrophysics
dc.titleProduction of H$_3^+$ via photodissociation of organic molecules in interstellar clouds
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