AIKAWA, Y.; WAKELAM, Valentine; HERSANT, F.; GARROD, R. T.; HERBST, E.

doi:10.1088/0004-637X/760/1/40

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AIKAWA, Y.

WAKELAM, Valentine
AMOR 2012

HERSANT, F.
FORMATION STELLAIRE 2012

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The Astrophysical Journal. 2012-11, vol. 760, p. 40

American Astronomical Society

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We investigate the molecular evolution and D/H abundance ratios that develop as star formation proceeds from a dense molecular cloud core to a protostellar core, by solving a gas-grain reaction network applied to a one-dimensional radiative hydrodynamic model with infalling fluid parcels. Spatial distributions of gas and ice-mantle species are calculated at the first-core stage, and at times after the birth of a protostar. Gas-phase methanol and methane are more abundant than CO at radii r <~ 100 AU in the first-core stage, but gradually decrease with time, while abundances of larger organic species increase. The warm-up phase, when complex organic molecules are efficiently formed, is longer-lived for those fluid parcels infalling at later stages. The formation of unsaturated carbon chains (warm carbon-chain chemistry) is also more effective in later stages; C+, which reacts with CH4 to form carbon chains, increases in abundance as the envelope density decreases. The large organic molecules and carbon chains are strongly deuterated, mainly due to high D/H ratios in the parent molecules, determined in the cold phase. We also extend our model to simulate simply the chemistry in circumstellar disks, by suspending the one-dimensional infall of a fluid parcel at constant disk radii. The species CH3OCH3 and HCOOCH3 increase in abundance in 104-105 yr at the fixed warm temperature; both also have high D/H ratios.< Réduire

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ISM: abundances

ISM: clouds

stars: formation

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From Prestellar to Protostellar Cores. II. Time Dependence and Deuterium Fractionation

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