Related papers: Interstellar Atomic Abundances
The luminosity of the central source in ionizing radiation is an essential parameter in a photoionized environment, and one of the most fundamental physical quantities one can measure. We outline a method of determining luminosity for any…
Over the course of its motion through the Galaxy, our solar system has encountered many interstellar environments of varying characteristics. Interstellar medium (ISM) density variations spanning seven orders of magnitude are commonly seen…
The observed oxygen abundances in a number of irregular galaxies have been compared with predictions of the closed-box model of chemical and photometric evolution of galaxies. Oxygen is found to be deficient with respect to the predicted…
Recent results on nearby interstellar gas and interstellar byproducts within the solar system are used to select among the equilibrium radiative transfer models of the nearest interstellar material of Slavin and Frisch (2002). Assuming…
Scattering and absorption of X-rays by interstellar dust is calculated for a model consisting of carbonaceous grains and amorphous silicate grains. The calculations employ realistic dielectric functions with structure near X-ray absorption…
We present preliminary results of an analysis of the iron depletion factor into dust grains for a sample of 20 planetary nebulae (PNe) from the Galactic bulge. We compare these results with the ones we obtained in a prior analysis of 28…
The iron depletion level and the gas-phase iron abundance in the hot ~10^6 K interstellar medium (ISM) is critical to the understanding of its energy balance as well as the thermal sputtering, cooling, and heating processes of dust grains.…
Molecular hydrogen (H2) is the primary component of the reservoirs of cold, dense gas that fuel star formation in our galaxy. While the H2 abundance is ultimately regulated by physical processes operating on small scales in the interstellar…
The dust abundance of the interstellar medium plays an important role in galaxy physics, the chemical evolution of matter and the absorption and re-emission of stellar light. The last years have seen a surge in observational and theoretical…
Interstellar hydrides -- that is, molecules containing a single heavy element atom with one or more hydrogen atoms -- were among the first molecules detected outside the solar system. They lie at the root of interstellar chemistry, being…
The diffuse interstellar medium (ISM) is an integral part of the evolution of the entire Galaxy. Metals are produced by stars and their abundances are the direct testimony of the history of stellar evolution. However, the interstellar dust…
We have derived the column densities of heavy elements in three gamma-ray burst (GRB) optical transients, associated with the circumburst or interstellar medium (ISM) of the host galaxy. In comparison with the same elements observed in…
We use very deep spectra obtained with the Ultraviolet-Visual Echelle Spectrograph in the Very Large Telescope in order to determine the physical conditions, the chemical abundances and the iron depletion factors of four H II regions of the…
Context. Previous studies have suggested that the Sun is relatively depleted in refractory elements compared to other solar twins or analogs, potentially as a result of planet formation. However, such conclusions are often limited by…
Interstellar dust is a significant component of matter in the galaxies. The dust owns its origin and reprocessing in a wide range of astrophysical environments. In order to understand the origin and evolution of the distinct types of…
The chemical abundances of metal-poor stars provide a great deal of information regarding the individual nucleosynthetic processes that created the observed elements and the overall process of chemical enrichment of the galaxy since the…
The recent discovery of high redshift dusty galaxies implies a rapid dust enrichment of their interstellar medium (ISM). To interpret these observations, we run a cosmological simulation in a 30$h^{-1}$ cMpc/size volume down to $z \approx…
We derive the abundance of 19 elements in a sample of 64 stars with fundamental parameters very similar to solar, which minimizes the impact of systematic errors in our spectroscopic 1D-LTE differential analysis, using high-resolution…
Recent interferometric surveys of nearby main-sequence stars show a faint but significant near-infrared excess in roughly two dozen systems, i.$\,$e. around $10\,\%$ to $30\,\%$ of stars surveyed. This excess is attributed to dust located…
The evolution of star-forming regions and their thermal balance are strongly influenced by their chemical composition, that, in turn, is determined by the physico-chemical processes that govern the transition between the gas phase and the…