Abstract

A brief history is given of astronomical observations of the spectra of heavy elements in stars, with emphasis on those elements produced by slow capture of neutrons in the stellar interior. As an example, an abundance analysis of the electrons zirconium through ruthenium, including the unstable element technetium, is described. Schemes for explaining the presence of technetium (probably ⁹⁹Tc with a half-life of 2 × 10⁵ years) and the presence of niobium (formed by decay of ⁹³Zr with a half-life of 1.5 × 10⁶ years) are discussed. The importance of radioactive decay of technetium from an excited nuclear state is stressed.

© 1984 Optical Society of America

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