相关论文: Molecular Line Profiles of Collapsing Gas Clouds

We have performed fully 3D simulations of the collapse of molecular cloud cores which obey the logatropic equation of state. By following the collapse of these cores from states of near hydrodynamic equilibrium, we are able to produce…

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…

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 formulate the problem of the formation and collapse of nonaxisymmetric protostellar cores in weakly ionized, self-gravitating, magnetic molecular clouds. In our formulation, molecular clouds are approximated as isothermal, thin (but with…

We use detailed numerical simulations of the coupled chemical, thermal and dynamical evolution of the gas in a turbulent molecular cloud to study the usefulness of the [CI] 609 micron and 370 micron fine structure emission lines as tracers…

We present theoretically-established values of the CO-to-H2 and C-to-H2 conversion factors that may be used to estimate the gas masses of external galaxies. We consider four distinct galaxy types, represented by M51, NGC 6946, M82 and SMC…

We calculate the evolution of molecular line profiles of HCO$^+$ and C$^{18}$O toward a dense core thatis forming inside a magnetized turbulent molecular cloud. Features of the profiles can be affected more significantly by coupled velocity…

We present observations of 25 transitions of 17 isotopologues of 9 molecules toward B335. With a goal of constraining chemical models of collapsing clouds, we compare our observations, along with data from the literature, to models of…

Studying the atomic-to-molecular transition is essential for understanding the evolution of interstellar medium. The linear edge of Taurus molecular cloud, clearly identified in the $^{13}$CO(1-0) intensity map, serves as an ideal site for…

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 investigate observational signatures of triggered star formation in bright rimmed clouds (BRCs) by using molecular line transfer calculations based on radiation-hydrodynamic radiatively-driven-implosion models. We find that for BRCs the…

We construct models of molecular clouds that are considered as ensembles of transient cores. Each core is assumed to develop in the background gas of the cloud, grow to high density and decay into the background. The chemistry in each core…

Redshifted self-absorption features in molecular lines are commonly interpreted as signatures of gravitational collapse in pre- and protostellar cores. The shape of the line profile then encodes information on the dynamics of the collapse.…

We have observed 23 Class 0 sources in the HCO+ J=4-3 and 3-2 lines. The mean bolometric temperature of the 16 sources with well-determined values is 44 K and the mean luminosity is 5.7 L_sun, excluding two sources of considerably higher…

Low-mass stars are generally understood to form by the gravitational collapse of the dense molecular clouds known as starless cores. Continuum observations have not been able to distinguish among the several different hypotheses that…

Gas infall motions play a crucial role in high-mass star formation and are characterized by observable signatures in the form of blue-shifted asymmetric spectral line profiles ("blue profiles"). However, the connection between blue profiles…

We present a unified model for molecular core formation and evolution, based on numerical simulations of converging, supersonic flows. Our model applies to star formation in GMCs dominated by large-scale turbulence, and contains four main…

The rotational transitions of carbon monoxide (CO) are the primary means of investigating the density and velocity structure of the molecular interstellar medium. Here we study the lowest four rotational transitions of CO towards…

We present synthetic line observations of a simulated molecular cloud, utilising a self-consistent treatment of the dynamics and time-dependent chemical evolution. We investigate line emission from the three most common CO isotopologues…

Theoretical and observational investigations have indicated that the abundance of carbon monoxide (CO) is very sensitive to intrinsic properties of the gaseous medium, such as density, metallicity, and the background UV field. In order to…