A search for interstellar gas – phase CO 2 ? Gas / solid state abundance ratios
نویسنده
چکیده
We present searches for gas–phase CO2 features in the ISO–SWS infrared spectra of four deeply embedded massive young stars, which all show strong solid CO2 absorption. The abundance of gas–phase CO2 is at most 2: 10 7 with respect to H2, and is less than 5% of that in the solid phase. This is in strong contrast to CO, which is a factor of 10–100 more abundant in the gas than in solid form in these objects. The gas/solid state ratios of CO2, CO and H2O are discussed in terms of the physical and chemical state of the clouds.
منابع مشابه
A search for interstellar gas-phase CO2? Gas: solid state abundance ratios
We present searches for gas–phase CO2 features in the ISO–SWS infrared spectra of four deeply embedded massive young stars, which all show strong solid CO2 absorption. The abundance of gas–phase CO2 is at most 2: 10 7 with respect to H2, and is less than 5% of that in the solid phase. This is in strong contrast to CO, which is a factor of 10–100 more abundant in the gas than in solid form in th...
متن کاملMolecular gas phase counterparts to solid state grain mantles features: implication for gas/grain chemistry
We present ISO SWS (AOT6) observations of the protostellar object RAFGL 7009S. This source is particularly interesting for the characterisation of chemistry arising from grain surfaces andmantles, since the solid state features ofmany simple molecules such asH2O,CO,CO2, CO2 andCH4 are detected, together with weaker features not yet unambiguously identified. Gas phase H2O, CO2, CH4 and CO can al...
متن کاملThe gas / solid methane abundance ratio toward deeply embedded protostars ?
We present the detection of ro-vibrational absorption lines of the deformation mode of gaseous CH 4 toward the massive protostars W 33A, and NGC 7538 : IRS9, using the SWS spectrometer on board of the Infrared Space Observatory. The observed lines indicate that the CH 4 gas is warm (T ∼ 90 K), and has a low abundance (∼ 4 10 −7). The CH 4 ice in these lines of sight is embedded in a polar matri...
متن کاملDiscovery of Interstellar Heavy Water
We report the discovery of doubly deuterated water (D2O, heavy water) in the interstellar medium. Using the James Clerk Maxwell Telescope and the Caltech Submillimeter Observatory 10 m telescope, we detected the 110–101 transition of para-D2O at 316.7998 GHz in both absorption and emission toward the protostellar binary system IRAS 16293 2422. Assuming that the D2O exists primarily in the warm ...
متن کاملChemical Abundance Ratios and Gas-phase Mixing in Dwarf Galaxy Evolution
Because of their low gravitational energies dwarf galaxies are greatly exposed to energetical influences by the interstellar medium, like e.g. stellar radiation, winds or explosions, or by their environment. While the metallicity depletion in dwarf galaxies can be explained in general by supernova-driven galactic winds, the reason for their low N/O ratios at low O abundance is not yet completel...
متن کامل