A new Sc II model atom has been constructed using up-to-date atomic data. To test it, we have carried out nonlocal thermodynamic equilibrium (non-LTE) calculations for three stars with reliably determined atmospheric parameters: the Sun, HD 61421 (Procyon), and 84937. Allowance departures from LTE leads to a decrease in root-mean-square abundance error compared case agreement, within limits of ...

Amorphous silicates in meteoritic samples are significant as potential surviving interstellar dust from the formation of Solar System. silicate-rich grains called GEMS, glass with embedded metal and sulfides, abundant anhydrous interplanetary particles some ultracarbonaceous Antarctic micrometeorites that have high presolar grain abundances. Some GEMS within these objects been confirmed to be p...

New abundance tables have been compiled for Cl chondrites and the solar photosphere and corona, based on a critical review of the literature to mid-1988. The meteorite data are generally accurate to +5-10%. Significant discrepancies between Sun and meteorites occur only for Fe, Mn, Ge, Pb, and W; other well-determined elements agree to &90/o on the average. There is no evidence for group fracti...

Supernova Environment and Triggered Molecular Cloud Collapse: I have been studying the operation of the r-process in a core collapse supernova just after the large flux of neutrinos and antineutrinos has blown the presupernova envelope off the newly formed neutron star [1,2]. The hot (10 K) neutron star surface will emit a wind largely composed of neutrons, but these will only build up r-proces...

Pre-solar grains of silicon carbide found in meteorites and interpreted as having had an origin around carbon stars from their isotopic composition, have all been found to be of the β-SiC polytype. Yet to date fits to the 11.3-µm SiC emission band of carbon stars had been obtained only for α-SiC grains. We present thin film infrared (IR) absorption spectra measured in a diamond anvil cell for b...