相关论文: Photodissociation of interstellar N2
Photodissociation of 14N2 and 14N15N occurs in interstellar clouds, circumstellar envelopes, protoplanetary discs, and other environments due to UV radiation from stellar sources and the presence of cosmic rays. This source of N atoms…
Many chemical models of dense interstellar clouds predict that the majority of gas-phase elemental nitrogen should be present as N2, with an abundance approximately five orders of magnitude less than that of hydrogen. As a homonuclear…
The envelopes of AGB stars are irradiated externally by ultraviolet photons; hence, the chemistry is sensitive to the photodissociation of N$_2$ and CO, which are major reservoirs of nitrogen and carbon, respectively. The photodissociation…
Soft x-ray radiation from the sun is responsible for the production of high energy photoelectrons in the D and E regions of the ionosphere, where they deposit most of their ionization energy. The photoelectrons created by this process are…
Processing by interstellar photons affects the composition of the icy mantles on interstellar grains. The rate of photodissociation in solids differs from that of molecules in the gas phase. The aim of this work was to determine an average,…
Nitrogen-bearing molecules display variable isotopic fractionation levels in different astronomical environments such as in the interstellar medium or in the Solar System. Models of interstellar chemistry are unable to induce nitrogen…
A new collection of photodissociation and photoionisation cross sections for 102 atoms and molecules of astrochemical interest has been assembled, along with a brief review of the basic processes involved. These have been used to calculate…
Photodissociation is the dominant removal process of molecules in any region exposed to intense ultraviolet (UV) radiation. This includes diffuse and translucent interstellar clouds, dense photon-dominated regions, high velocity shocks, the…
Molecular clouds (MCs) are the birthplaces of new stars in galaxies. A key component of MCs are photodissociation regions (PDRs), where far-ultraviolet radiation plays a crucial role in determining the gas's physical and chemical state.…
Ultraviolet photodesorption of molecules from icy interstellar grains can explain observations of cold gas in regions where thermal desorption is negligible. This non-thermal desorption mechanism should be especially important where UV…
Aims. Photodissociation by UV light is an important destruction mechanism for CO in many astrophysical environments, ranging from interstellar clouds to protoplanetary disks. The aim of this work is to gain a better understanding of the…
We study the chemical evolution of interstellar grain mantle by varying the physical parameters of the interstellar medium (ISM). To mimic the exact interstellar condition, gas grain interactions via accretion from the gas phase and…
We present three-dimensional astrochemical simulations and synthetic observations of magnetised, turbulent, self-gravitating molecular clouds. We explore various galactic interstellar medium environments, including cosmic-ray ionization…
We have designed an improved algorithm that enables us to simulate the chemistry of cold dense interstellar clouds with a full gas-grain reaction network. The chemistry is treated by a unified microscopic-macroscopic Monte Carlo approach…
We investigate the importance of the shielding of chemical photorates by molecular hydrogen photodissociation lines and the carbon photoionization continuum deep within models of photon dominated regions. In particular, the…
There is a robust polyatomic chemistry in diffuse, partially-molecular interstellar gas that is readily accessible in absorption at radio/mm/sub-mm wavelengths. Accurate column densities are derived owing to the weak internal excitation, so…
The presence of dust can strongly affect the chemical composition of the interstellar medium. We model the chemistry in photodissociation regions (PDRs) using both gas-phase and dust-phase chemical reactions. Our aim is to determine the…
UV ice photodesorption is an important non-thermal desorption pathway in many interstellar environments that has been invoked to explain observations of cold molecules in disks, clouds and cloud cores. Systematic laboratory studies of the…
Carbon monoxide (CO) is a poor tracer of H$_{2}$ in the diffuse interstellar medium (ISM), where most of the carbon is not incorporated into CO molecules unlike the situation at higher extinctions. We present a novel, indirect method to…
Isotopologue abundance ratios are important to understand the evolution of astrophysical objects and ultimately the origins of a planetary system like our own. Being nitrogen a fundamental ingredient of pre-biotic material, understanding…