相关论文: Formation of PAHs and Carbonaceous Solids in Gas-P…

The life-cycle of cosmic dust grains is far from being understood and the origin and evolution of interstellar medium (ISM) grains is still under debate. In the ISM, the cosmic dust destruction rate is faster than the production rate by…

Small organic molecules are thought to provide building blocks for the formation of complex interstellar polycyclic aromatic hydrocarbons (PAHs). However, the underlying chemical mechanisms remain unclear, particularly concerning the role…

The low carbon content of Earth and primitive meteorites compared to the Sun and interstellar grains suggests that carbon-rich grains were destroyed in the inner few astronomical units of the young solar system. A promising mechanism to…

Atomic ions are mostly neutralized by small grains (or PAH molecules) in current theories of heating and cooling in cool diffuse clouds; in the main they do not recombine with free electrons. This alters the ionization balance by depressing…

There is accumulating evidence for the presence of complex molecules, including carbon-bearing and organic molecules, in the interstellar medium. Much of this evidence comes to us from studies of chemical composition, photo- and…

Two different types of experiments were performed. In the first experiment, we studied the low-temperature condensation of vaporized graphite inside bulk liquid helium, while in the second experiment, we studied the condensation of single…

Fullerenes have recently been identified in space and they may play a significant role in the gas and dust budget of various astrophysical objects including planetary nebulae (PNe), reflection nebulae (RNe) and H II regions. The tenuous…

Polycyclic aromatic hydrocarbons (PAHs) have been detected in numerous circumstellar discs. We propose the continuous processing of PAHs through clustering, adsorption on dust grains, and their reverse-processes as key mechanisms to reduce…

Polycyclic aromatic hydrocarbons (PAHs) and fullerenes play a major role in the physics and chemistry of the interstellar medium. Based on a number of recent experimental and theoretical investigations we developed a model in which PAHs are…

We have carried out an investigation of the chemical evolution of gas in different carbon-rich circumstellar environments. Previous studies have tended to invoke terrestrial flame chemistries, based on acetylene (C2H2) combustion to model…

Dust grains absorb half of the radiation emitted by stars throughout the history of the universe, re-emitting this energy at infrared wavelengths. Polycyclic aromatic hydrocarbons (PAHs) are large organic molecules that trace…

Molecular hydrogen (H2) is the main constituent of the gas in the planet-forming disks that surround many PMS stars. H2 can be incorporated in the atmosphere of the giant planets. HD has been detected in a few disks and can be considered…

Context. Icy dust grains play an important role in the formation of complex inter- and circumstellar molecules. Observational studies show that polycyclic aromatic hydrocarbons (PAHs) are abundantly present in the ISM in the gas phase. It…

The high interstellar abundances of polycyclic aromatic hydrocarbons (PAHs) and their size distribution are the result of complex chemical processes implying dust, UV radiation, and the main gaseous components (H, C+, and O). These…

We report on simulations of the formation of the first stars in the Universe, where we identify regions of hot atomic gas (fH2 < 10-6) at densities above 10-14 g/cc, heated to temperatures ranging between 3000 and 8000 K. Within this…

Optically thin cooling gas at most temperatures above 30K will make condensations by pressure pushing material into cool dense regions. This works without gravity. Cooling condensations will flatten and become planar/similarity solutions.…

Interstellar carbonaceous dust is mainly formed in the innermost regions of circumstellar envelopes around carbon-rich asymptotic giant branch (AGB) stars. In these highly chemically stratified regions, atomic and diatomic carbon, along…

Abundances and partitioning of ices and gases produced by gas-grain chemistry are governed by adsorption and desorption on grains. Understanding astrophysical observations rely on laboratory measurements of adsorption and desorption rates…

Condensation processes, which are responsible for the main chemical differences between gas and solids in the Galaxy, are the major mechanisms that control the cycle of dust from evolved stars to planetary systems. However, they are still…

Dust determines the temperature structure of protoplanetary disks. However, dust temperature determinations almost invariably rely on a complex modeling of the Spectral Energy Distribution. We attempt a direct determination of the…