This element was discovered by P. E. Lecoq de Boisbaudran in Paris in 1886. The name comes from the Greek dysprositos (hard to obtain).
DyI 5.9 eV, DyII 11.7 eV, DyIII 22.8 eV, DyIV 41.5 eV.
Absorption lines of DyI
DyI is absent in the sun, but present in one M2III star (Davis 1947).
Absorption lines of DyII
Several weak lines of DyII were reported in one F OIb star, in one F 5V star (Kato and Sadakane 1986) and in late type giants. W(4000) = 0.047 according to Reynolds et al. (1988) for F 5V.
DyII is present in Ap stars in general (Cowley 1976, Adelman et al. 1979). In severalAp stars with strong Dy II lines, Aikman et al. (1979) also detected DyIII, which fact was confirmed by Cowley and Greenberg (1987). DyII is also present in at least one late Am star (van t'Veer-Menneret et al. 1988) with W(3944) = 0.152.
DyII was observed by Gilroy et al. (1988) in metal-weak G- and K-type dwarfs. These authors find the element to be overabundant with respect to iron. See also the discussion on rare earths.
DyI lines are enhanced in some Ba stars (Lambert 1985).
DyII lines were found in at least one S-type star (Bidelman 1953).
Dy occurs in the form of seven stable isotopes - Dy 156, 158, 160, 161, 162, 163 and 164. In the solar system Dy161 represents 19% and Dy 162, 163 and 164 represent 25%, 25% and 28% respectively. The rest is made up by the other stable isotopes. There exist 14 unstable isotopes and isomers, among them Dy154 with a half life of 106 years.
Dy is produced by a variety of processes; Dy156 and Dy158 by the p process, Dy161 and Dy163 by the r process, Dy160 by the s process and Dy162 and Dy164 by either the r or the s process.
Published in "The Behavior of Chemical Elements in Stars", Carlos Jaschek and Mercedes Jaschek, 1995, Cambridge University Press.