Related papers: Chemistry and dynamics of the prestellar core L154…
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…
Recent high-resolution studies of the L1544 protostellar core by Tafalla et al. and Williams et al. reveal the structure and kinematics of the gas. The observations of this prestellar core provide a natural test for theoretical models of…
We have coupled a chemical model with two dynamical models of collapsing low mass star-forming cores to predict abundances across the core of the commonly used infall tracers, CS and HCO$^+$, at various stages of the collapse. The models…
We quantify if the chemical abundance gradients given by a dynamical model of core collapse including time-dependent changes in density and temperature differ greatly from abundances derived from static models, where the density and…
We analyze an ensemble of simulated prestellar cores to facilitate interpretation of structure, kinematics, and lifetime of observed cores. While our theory predicts a "characteristic" density for star formation, it also predicts that the…
We have compared molecular line emission to dust continuum emission and modeled molecular lines using Monte Carlo simulations in order to study the depletion of molecules and the ionization fraction in three preprotostellar cores, L1512,…
Both analytic and numerical radiative transfer models applied to high spectral resolution CS and N2H+ data give insight into the evolutionary state of L1551 MC. This recently discovered pre-protostellar core in L1551 appears to be in the…
Although surveys of infall motions in dense cores have been carried out for years, few surveys have focused on mapping infall across cores using multiple spectral line observations. To fill this gap, we present IRAM 30-m Telescope maps of…
We have compared the intensity distribution of molecular line emission with that of dust continuum emission, and modeled molecular line profiles in three different preprotostellar cores in order to test how dynamical evolution is related to…
Direct observational measurements of the magnetic field strength in prestellar cores typically find supercritical mass-to-flux ratios, suggesting that the magnetic field is insufficient to prevent gravitational collapse. These measurements…
The chemistry of H2O, CO and other small molecular species in an isolated pre-stellar core, L1544, has been assessed in the context of a comprehensive gas-grain chemical model, coupled to an empirically constrained physical/dynamical model.…
We compute numerical simulations of spherical collapse triggered by a slow increase in external pressure. We compare isothermal models to models including cooling with a simple but self-consistent treatment of the coupling between gas,…
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…
The collapse of weakly turbulent prestellar cores is a critical stage in the process of star formation. Being highly non-linear and stochastic, the outcome of collapse can only be explored theoretically by performing large ensembles of…
Models of prestellar cores often assume that the cores are isolated from their environment - material outside the core boundary plays no role in the subsequent evolution. This is unlikely to be the case in reality, where cores are located…
Aims. We investigate the effect of chemistry on the stability of starless cores against gravitational collapse. Methods. We combine chemical and radiative transfer simulations in the context of a modified Bonnor-Ebert sphere to model the…
We revisit the interpretation of blue-excess molecular lines from dense collapsing cores, considering recent numerical results that suggest prestellar core collapse occurs from the outside-in, and not inside-out. We thus create synthetic…
Molecular line observations of starless (prestellar) cores combined with a chemical evolution modeling and radiative transfer calculations are a powerful tool to study the earliest stages of star formation. However, conclusions drawn from…
In star-forming regions, molecular cloud history and dynamics set the trend in the chemical composition. Ice formation, in particular, is affected by the evolution of physical conditions, which can lead to different ice compositions within…
The theory of how low mass stars form from the collapse of a dense molecular cloud core has been well-established for decades. Thanks to significant progress in computing and numerical modelling, more physical models have been developed and…