New results for ion–molecule reactions of HC3N in dense interstellar clouds

Chlorine in Dense Interstellar Clouds: the Abundance

We report the first detection of a chlorine-bearing molecular species in the interstellar medium via emission from the J = 1----> 0 transition of HCl at 625.9 GHz toward OMC-1. The relative strengths, widths, and velocities of the resolved hyperfine components are consistent with moderate optical depth emission originating from dense, quiescent molecular cloud material (VLsR = 9 km s1). The ove...

Elemental nitrogen partitioning in dense interstellar clouds.

Many chemical models of dense interstellar clouds predict that the majority of gas-phase elemental nitrogen should be present as N(2), with an abundance approximately five orders of magnitude less than that of hydrogen. As a homonuclear diatomic molecule, N(2) is difficult to detect spectroscopically through infrared or millimeter-wavelength transitions. Therefore, its abundance is often inferr...

Fractional abundances of molecules in dense interstellar clouds: A compendium of recent model results

— In this paper we present calculated fractional abundances in dense interstellar clouds for selected atomic and molecular species using three different homogeneous, pseudo-time-dependent models discussed by Bettens, Lee, & Herbst (1995): the new standard model, the new neutral-neutral model, and model 4. We have run each model with 3 different hydrogen densities – 10, 10, and 10 cm−3 – and two...

The Chemistry of Transient Dense Cores in Interstellar Clouds

A sensitivity study of the neutral - neutral reactions C + C 3 and C + C 5 in cold dense interstellar clouds

A sensitivity study of the neutral-neutral reactions C + C 3 and C + C 5 in cold dense interstellar clouds ABSTRACT Aims. Chemical networks used for models of interstellar clouds contain many reactions, some of them with poorly determined rate coefficients and/or products. In this work, we report a method for improving the predictions of molecular abundances using sensitivity methods and ab ini...