相关论文: Rusty old stars: a source of the missing interstel…
The origin and depletion of iron differ from all other abundant refractory elements that make up the composition of the interstellar dust. Iron is primarily synthesized in Type Ia supernovae (SNe Ia) and in core collapse supernovae (CCSN),…
The abundant forms in which the major elements in the universe exist have been determined from numerous astronomical observations and meteoritic analyses. Iron (Fe) is an exception, in that only depletion of gaseous Fe has been detected in…
We consider a small sample of oxygen-rich, asymptotic giant branch stars in the Large Magellanic Cloud, observed by the Spitzer Space Telescope, exhibiting a peculiar spectral energy distribution, which can be hardly explained by the common…
We present the first attempt to determine the iron abundance in hot central stars of planetary nebulae. We perform an analysis with fully metal-line blanketed NLTE model atmospheres for a sample of ten stars (T_eff >= 70.000 K) for which…
We present a fit to the spectral energy distribution of OH 127.8+0.0, a typical asymptotic giant branch star with an optically thick circumstellar dust shell. The fit to the dust spectrum is achieved using non-spherical grains consisting of…
We constrain the iron abundance in a sample of 33 low-ionization Galactic planetary nebulae (PNe) using [Fe III] lines and correcting for the contribution of higher ionization states with ionization correction factors (ICFs) that take into…
In the interstellar medium of the Milky Way, certain elements -- e.g., Mg, Si, Al, Ca, Ti, Fe -- reside predominantly in interstellar dust grains. These grains absorb, scatter, and emit electromagnetic radiation, heat the interstellar…
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 chemical composition of stars with extremely low metal contents (taking ``metals'' to mean all elements other than hydrogen and helium) provides us with information on the masses of the stars that produced the first metals. Such a…
What might be the most appropriate set of interstellar reference abundances of chemical elements (both in gas and in dust) relative to hydrogen has been a subject of much discussion in the past decade. While historically the Sun has been…
Polluted white dwarfs provide unique constraints on the elemental compositions of planetary bodies. The tidal disruption of accreting bodies is thought to form circumstellar dusty disks, whose emission spectra could offer additional…
A broad array of interstellar absorption features that appear in the ultraviolet spectra of bright sources allows us to measure the abundances and ionization states of many important heavy elements that exist as free atoms in the…
To explain the properties of dust in the interstellar medium (ISM), the presence of a refractory organic mantle is necessary. The outflows of AGB stars are among the main contributors of stellar dust to the ISM. We present the first study…
We present a first systematic investigation of the iron abundance in very hot (Teff>50,000K) hydrogen-deficient post-AGB stars. Our sample comprises 16 PG1159 stars and four DO white dwarfs. We use recent FUSE observations as well as HST…
The chemical composition of the most metal-deficient stars reflects the composition of the gas from which they formed. These old stars provide crucial clues to the star formation history and the synthesis of chemical elements in the early…
Interstellar dust appears in a number of roles in the interstellar medium. Historically, the most familiar one is as a source of extinction in the optical. Absorbed optical and ultraviolet light heats the dust, whence infrared (including…
We examine the mid-infrared fluxes and spectral energy distributions for metal-poor stars with iron abundances [Fe/H] $\lesssim-5$, as well as two CEMP-no stars, to eliminate the possibility that their low metallicities are related to the…
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…
Available X-ray data are collected and organized concerning the iron and gas content of galaxy clusters and groups, together with the optical luminosity, mass and iron abundance of cluster galaxies. Several astrophysical inferences are then…
Recent works have demonstrated a surprisingly small variation of the dust-to-metals ratio in different environments and a correlation between dust extinction and the density of stars. Naively, one would interpret these findings as strong…