Metal/silicate fractionation in the solar system

Low temperature condensation from the solar nebula

Context. To calibrate automatic pipelines that determine atmospheric parameters of stars, one needs a sample of stars, or “benchmark stars”, with well-defined parameters to be used as a reference.Aims. We provide detailed documentation of the iron abundance determination of the 34 FGK-type benchmark stars that are selected to be the pillars for calibration of the one billion Gaia stars. They cover a wide range of temperatures, surface gravities, and metallicities.Methods. Up to seven different methods were used to analyze an observed spectral library of high resolutions and high signal-to-noise ratios. The metallicity was determined by assuming a value of effective temperature and surface gravity obtained from fundamental relations; that is, these parameters were known a priori and independently from the spectra.Results. We present a set of metallicity values obtained in a homogeneous way for our sample of benchmark stars. In addition to this value, we provide detailed documentation of the associated uncertainties. Finally, we report a value of the metallicity of the cool giant ψ Phe for the first time.

/pdf/gaia-fgk-benchmark-stars-metallicity-1q4blp6my2.pdf

Gaia FGK benchmark stars: Metallicity

Satellites of the Outer Planets: Their Physical and Chemical Nature

The discussion of the chemical composition of the sun includes the basic methods of analysis, a table of solar elemental abundances, and the particularly difficult problems of the abundances of helium and iron. (JFP)

https://science.sciencemag.org/content/sci/191/4233/1223.full.pdf

The chemical composition of the sun.

Shock-Tube Measurements of Absolute gf-VALUES for Fe I

MEASUREMENTS OF OSCILLATOR STRENGTHS FOR Fe I AND Fe II.

The foil excitation technique, wherein a high-energy (2-MeV) beam of ions is passed through a thin (\ensuremath{\sim}1000 \AA{}) carbon foil, has been used to measure lifetimes of excited electronic states in nitrogen II through v The lifetimes were obtained by measuring the decay of optical radiation as a function of distance from the foil The excited states were considerably above the ground state of the particular ion, and as a consequence, nonlinear population by cascading was minimal Because of the low speed of the optical system ($\frac{f}{88}$), only the most intense multiplets and members of multiplets were observed The wavelength range in which transitions were observed was 2000 to 5000 \AA{} The lifetimes measured were between 04 and 10 nsec In general, these lifetimes apply to all the members of the multiplet, since the levels of origin as well as the levels of termination are closely spaced with respect to the total-angular-momentum quantum number $J$ Where it is possible, these lifetimes are compared with available calculations Some transitions are untabulated and were identified through the use of a computer program

Gordon W. Wares

Papers

Shock-Tube Measurements of Absolute gf-VALUES for Fe I

MEASUREMENTS OF OSCILLATOR STRENGTHS FOR Fe I AND Fe II.

Radiative Lifetimes of Excited Electronic States in Ionic Species of Nitrogen

Additional Shock-Tube Measurements of Absolute CR i gƒ-VALUES

Some Additional Shock-Tube Absolute gf Values of CR I and CR II.