While beta Pic is known to host silicates in ring-like structures, whether the properties of these silicate dust vary with stellocentric distance remains an open question. We re-analyze Pictoris debris disk spectrum from Spitzer Infrared Spectrograph (IRS) and a new IRTF/SpeX investigate trends Fe/Mg ratio, shape, crystallinity grains as function wavelength, proxy for distance. By analyzing re-...

Hafnia is of interest in thermal and environmental barrier coatings, but little known about its response to molten silicate attack. This article investigates that using two model melts, compares it with pure ZrO2 examines the effect YO1.5 additions. HfO2 was found form HfSiO4 acidic melts undergoes grain boundary penetration basic which do not exhibit reactive crystallization. The latter can be...

The abundant phyllosilicate and carbonate minerals characterizing most of the returned particles from asteroid Ryugu suggest a history extensive aqueous alteration on its parent body, similar to rare mineralogically altered, but chemically primitive, CI (Ivuna-type) chondrite meteorites. Particle C0009 differs other examined so far by containing anhydrous silicates at level ~0.5 vol%, thus can ...

While the generation of aryl radicals by photoredox catalysis under reductive conditions is well documented, it has remained challenging an oxidative pathway. Because easy photo-oxidation alkyl bis-catecholato silicates, a general study phenyl silicates bearing substituted catecholate ligands been achieved. The newly synthesized have fully characterized, and their reactivity explored. It was fo...

We present spectroscopic observations of a large sample of Herbig Ae stars in the 10μm spectral region. We perform compositional fits of the spectra based on properties of homogeneous as well as inhomogeneous spherical particles, and derive the mineralogy and typical grain sizes of the dust responsible for the 10μm emission. Several trends are reported that can constrain theoretical models of d...

Introduction: The presence of crystalline silicates in the co-mae of comets, inferred through infrared astronomical observations , has been a long-standing puzzle (e.g., [1]). Crystalline silicates are unexpected if comets are composed of pristine interstellar material, since interstellar silicates are almost entirely amorphous[2]. Heating to > 1100K can anneal silicates to crystallinity, but n...