From Prestellar to Protostellar Cores II. Time Dependence and Deuterium Fractionation
Oct, 2012Citations per year
Abstract: (arXiv)
We investigate the molecular evolution and D/H abundance ratios that develop as star formation proceeds from a dense-cloud core to a protostellar core, by solving a gas-grain reaction network applied to a 1-D 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 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 in-falling at later stages. The formation of unsaturated carbon chains (warm carbon-chain chemistry) is also more effective in later stages/ C, which reacts with CH 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 1-D infall of a fluid parcel at constant disk radii. The species CHOCH and HCOOCH increase in abundance in yr at the fixed warm temperature/ both also have high D/H ratios.Note:
- accepted to ApJ. 55 pages, 7 figures, 3 tables
- ISM: abundances
- ISM: clouds
- stars: formation
References(149)
Figures(11)