Quantitative technetium abundances in the long-period variables Chi Cygni and Omicron Ceti

The authors have analyzed spectra of 2.4 Å mm-1 dispersion to derive abundances of V, Zr, Nb, and Tc in χ Cygni, ο Ceti, and R Lyrae. They find a large Tc abundance in χ Cyg and a smaller amount of Tc in Mira. Accompanying the enhanced Tc in Mira is a surprisingly low abundance of Nb. The enhancement of Tc in χ Cyg can be explained as part of a general enhancement of heavy elements by neutron capture which is characteristic of S and MS stars. For Mira the explanation is less obvious because there is no apparent enhancement of heavy elements except for Tc. The depletion of Nb leads the authors to suggest that a very small pulse of neutrons could be responsible for this apparent anomaly.