相关论文: Modelling the molecular composition and nuclear-sp…
The physical conditions in a collapsing cloud can be traced by observations of molecular lines. To correctly interpret these observations the abundance distributions of the observed species need to be derived. The chemistry in a collapsing…
The nuclear-spin chemistry of interstellar water is investigated using the University of Grenoble Alpes Astrochemical Network (UGAN). This network includes reactions involving the different nuclear-spin states of the hydrides of carbon,…
We have studied the chemistry of nitrogen--bearing species during the initial stages of protostellar collapse, with a view to explaining the observed longevity of N2H+ and NH3 and the high levels of deuteration of these species. We followed…
We develop analytic approximations to the density evolution of prestellar cores, based on the results of hydrodynamical simulations. We use these approximations as input for a time-dependent gas-grain chemical code to investigate the…
The gravitational collapse of a spherical cloud core is investigated by numerical calculations. The initial conditions of the core lie close to the critical Bonnor-Ebert sphere with a central density of \sim 10^4 cm^{-3} in one model…
We develop a detailed chemical network relevant to the conditions characteristic of prestellar core collapse. We solve the system of time-dependent differential equations to calculate the equilibrium abundances of molecules and dust grains,…
The quantity of NH3 produced on grain surfaces in the prestellar core is thought to be one of the determining factors regarding the chemical complexity achievable at later stages of stellar birth. In order to investigate how this quantity…
The study of prestellar cores is critical as they set the initial conditions in star formation and determine the final mass of the stellar object. To date, several hypotheses are describing their gravitational collapse. We perform detailed…
We present a new gas-grain chemical model for the combined isotopic fractionation of carbon and nitrogen in molecular clouds, in which the isotope chemistry of carbon and nitrogen is coupled with a time-dependent description of spin-state…
We determine the ortho/para ratios of NH2D and NHD2 in two dense, starless cores, where their formation is supposed to be dominated by gas-phase reactions, which, in turn, is predicted to result in deviations from the statistical spin…
We study the changes in physical and chemical conditions during the collapse of a pre--protostellar core, starting from initial conditions appropriate to a dense molecular cloud and proceeding to the ``completely depleted'' limit. We follow…
We present PrestaLine: Gorynych, a comprehensive numerical tool designed to model the dynamical, chemical, and spectral evolution of collapsing molecular cores from the prestellar phase to protostellar accretion. The code integrates three…
The molecular evolution that occurs in collapsing prestellar cores is investigated. To model the dynamics, we adopt the Larson-Penston (L-P) solution and analogues with slower rates of collapse. For the chemistry, we utilize the new…
We investigate differences in the molecular abundances between magnetically super- and sub-critical prestellar cores, performing three-dimensional non-ideal magnetohydrodynamical (MHD) simulations with varying densities and magnetic field…
We discuss recent models of chemical evolution in the developing and collapsing protostellar envelopes associated with low-mass star formation. In particular, the effects of depletion of gas-phase molecules onto grain surfaces is…
We study molecular hydrogen formation in and on solids. We construct a model with surface sites and bulk sites capable of describing (1) the motion and exchange of H and H_2 between surface and bulk, (2) the recombination of H and…
We investigated the chemistry of nitrogen--containing species, principally isotopomers of CN, HCN, and HNC, in a sample of pre-protostellar cores. We used the IRAM 30 m telescope to measure the emission in rotational and hyperfine…
We present here the application of a model for a mass circulation mechanism in between the H-burning shell and the base of the convective envelope of low mass AGB stars, aimed at studying the isotopic composition of those presolar grains…
The aim of the present work is to perform a comprehensive analysis of the interstellar chemistry of nitrogen, focussing on the gas-phase formation of the smallest polyatomic species and in particular nitrogen hydrides. We present a new…
The collapse of dense cores with different metallicities is studied by hydrodynamical calculations coupled with detailed chemical and radiative processes. For this purpose, we construct a simple chemical network with non-equilibrium…