Metallicity Determinations from Ultraviolet‐Visual Spectrophotometry. I. The Test Sample

Abstract

New visual spectrophotometric observations of non-supergiant solar neighborhood stars are combined with IUE Newly Extracted Spectra (INES) energy distributions in order to derive their overall metallicities, [M/H]. This fundamental parameter, together with effective temperature and apparent angular diameter, is obtained by applying the flux-fitting method while surface gravity is derived from the comparison with evolutionary tracks in the theoretical H-R diagram. Trigonometric parallaxes for the stars of the sample are taken from the Hipparcos Catalogue. The quality of the flux calibration is discussed by analyzing a test sample via comparison with external photometry. The validity of the method in providing accurate metallicities is tested on a selected sample of G-type stars with well-determined atmospheric parameters from recent high-resolution spectral analysis. The extension of the overall procedure to the determination of the chemical composition of all the INES non-supergiant G-type stars with accurate parallaxes is planned in order to investigate their atmospheric temperature structure.

Seismological Analysis of the Stars γ Serpentis and ι Leonis: Stellar Parameters and Evolution

“…It is very interesting to see that the value of the large spacings decreases as the stars evolve toward lower effective temperature and larger radius. It is clear from the top panel of Figure 7 that the range of radius error for Ser is predicted to be about 1% -2%, comparable to the results given by Morossi et al (2002) and Thévenin et al (2006). However, the estimated radius of Leo is slightly smaller than the value of Thévenin et al (2006).…”

“…Here Thévenin et al (2006) and (for Ser) Morossi et al (2002). the helium abundance Y, which cannot be observed directly, was computed from the Galactic helium enrichment ratio ÁY/ÁZ.…”

“…With a rapid increase in the number of observations, the photometric and spectroscopic determination of stellar atmospheric parameters for nearby main-sequence stars of spectral classes F, G, and K has improved tremendously on the basis of data from the Hipparcos, IRAS, and IUE satellites (ESA 1997;Allende Prieto et al 2000;Habing et al 2001;Morossi et al 2002;Bryden et al 2006). Along with the stellar parameters, theoretical evolutionary tracks from stellar interior calculations are obtained by comparison with observed Hertzsprung-Russell (H-R) diagrams.…”

Metallicities of the SPB stars from the IUE ultraviolet spectra

“…Smith & Dworetsky (1993) obtained abundances of the iron group elements on the basis of the high-resolution IUE spectra and found the iron abundance of −0.14 dex. Morossi et al (2002) determined [m/H] = −0.05 ± 0.07 from the IUE/INES lowresolution spectra combined with the visual data. For τ Her we found the metal abundance of −0.18 ± 0.07 and −0.17 ± 0.06 for NEWSIPS and INES calibrations, respectively.…”

“…Aznar Cuadrado & Jeffery (2001) obtained parameters (T eff , θ, E(B − V) and [He/H]) of sdB stars on the basis of the IUE observations. Recently, Morossi et al (2002) used the IUE spectra, combined with visual spectrophotometric observations, to derive [m/H], T eff and θ for 53 stars in the solar neighborhood.…”