Quantitative technetium and niobium abundances in heavy-element stars

Abstract

view Abstract Citations (50) References (29) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Quantitative technetium and niobium abundances in heavy-element stars. Smith, V. V. ; Wallerstein, G. Abstract The 5924 A intercombination line of Tc I was used to derive Tc abundances in R CMi and CY Cyg and upper limits in two additional stars. In addition, abundances of V, Zr, Nb, Mo, and Ru relative to Ti in six stars were derived. The ratios of Tc/Mo indicate that very little decay of Tc has taken place since the last neutron exposure, which must have occurred less than 400,000 years ago. The abundance of Nb indicates that nearly complete decay of Zr-93 has taken place, which requires a time scale of several times one-million years. This is interpreted as indicating that multiple neutron capture events, probably shell flashes, have occurred and the Nb produced by the decay of Zr-93 has been convected out of the shell flashing region and thus has been protected from neutron capture during the most recent flashes which produced the observed Tc. Publication: The Astrophysical Journal Pub Date: October 1983 DOI: 10.1086/161409 Bibcode: 1983ApJ...273..742S Keywords: Abundance; Heavy Elements; Late Stars; Metallic Stars; Niobium; Technetium; Line Spectra; Nuclear Fusion; Quantitative Analysis; Spectral Line Width; Spectrum Analysis; Stellar Evolution; Stellar Spectrophotometry; Astrophysics full text sources ADS | data products SIMBAD (6)