相关论文: Gas-phase condensation of carbonated silicate grai…
The formation and growth of refractory matter on pre-existing interstellar dust grain surfaces was studied experimentally by annealing neon-ice matrices in which potential precursors of silicate grains (Mg and Fe atoms, SiO and SiO$_2$…
The heavy mass loss observed in evolved asymptotic giant branch stars is usually attributed to a two-step process: atmospheric levitation by pulsation-induced shock waves, followed by radiative acceleration of newly formed dust grains.…
We investigate the formation of silicon carbide (SiC) grains in the framework of dust-driven wind around pulsating carbon-rich Asymptotic Giant Branch (C-rich AGB) stars in order to reveal not only the amount but also the size distribution.…
Experimental results on the formation of molecular hydrogen on amorphous silicate surfaces are presented for the first time and analyzed using a rate equation model. The energy barriers for the relevant diffusion and desorption processes…
Silicate dust grains in the interstellar medium are known to be mostly amorphous, yet crystalline silicate grains have been observed in many long-period comets and in protoplanetary disks. Annealing of amorphous silicate grains into…
Current knowledge suggests that the dust-driven wind scenario provides a realistic framework for understanding mass loss from C-rich AGB stars. For M-type objects, however, recent detailed models demonstrate that radiation pressure on…
The basic mechanism responsible for the widespread condensation of MgS in the outflows from carbon rich stars on the tip of the AGB is discussed with the aim of developing a condensation model that can be applied in model calculations of…
High spatial resolution techniques have given valuable insights into the mass loss mechanism of AGB stars, which presumably involves a combination of atmospheric levitation by pulsation-induced shock waves and radiation pressure on dust.…
Experimental results on the formation of molecular hydrogen on amorphous silicate surfaces are presented and analyzed using a rate equation model. The energy barriers for the relevant diffusion and desorption processes are obtained. They…
Amorphous silicate dust is a major component in the interstellar and circumstellar dust formed in the outflow of asymptotic giant branch (AGB) stars. Although iron depletion is observed in the interstellar medium (ISM), the exact form and…
The condensation of complex silicates with pyroxene and olivine composition at conditions prevailing in molecular clouds has been experimentally studied. For this purpose, molecular species comprising refractory elements were forced to…
We investigate the composition and shape distribution of silicate dust grains in the interstellar medium. The effect of the amount of magnesium in the silicate lattice is studied. We fit the spectral shape of the interstellar 10 mu…
We investigate the IR spectral features of a sample of D-type symbiotic stars. Analyzing unexploited ISO-SWS data, deriving the basic observational parameters of dust bands and comparing them with respect to those observed in other…
We investigate the impact of dust-induced gas fragmentation on the formation of the first low-mass, metal-poor stars (< 1Msun) in the early universe. Previous work has shown the existence of a critical dust-to-gas ratio, below which dust…
Whether ice in cold cosmic environments is physically separated from the silicate dust or mixed with individual silicate moieties is not known. However, different grain models give very different compositions and temperatures of grains. The…
Stellar winds observed in asymptotic giant branch (AGB) stars are usually attributed to a combination of stellar pulsations and radiation pressure on dust. Shock waves triggered by pulsations propagate through the atmosphere, compressing…
The dust formation process in the winds of Asymptotic Giant Branch stars is discussed, based on full evolutionary models of stars with mass in the range $1$M$_{\odot} \leq$M$\leq 8$M$_{\odot}$, and metallicities $0.001 < Z <0.008$. Dust…
Optical constants of non-stoichiometric amorphous magnesium-iron silicates are determined. It is demonstrated that these can well reproduce the observed mid-infrared emission spectra of evolved stars. Stoichiometric and non-stoichiometric…
The winds observed around AGB stars are generally attributed to radiation pressure on dust formed in the dynamical atmospheres of these long-period variables. The composition of wind-driving grains is affected by a feedback between their…
Glass with embedded metal and sulfides (GEMS) is a major component of chondritic porous interplanetary dust particles. Although GEMS is one of the most primitive components in the Solar System, its formation process and conditions have not…