This element was discovered by L. Nilson in Uppsala, Sweden in 1879. Its name comes from Scandia (Scandinavia).
ScI 6.5 eV, ScII 12.8 eV, ScIII 24.8 eV, ScIV 73.5 eV, ScV 91.7eV, ScVI 111.1 eV, ScVII 138 eV.
Absorption lines of ScI
|5671 (a12-resonance line)||5343(4)|
ScI (see for instance 5671) appears in mid-F-type stars and grows monotonically toward later types. From late G-type onwards, a positive luminosity effect is visible for supergiants.
Emission lines of Scl
The line at 3907(8) is seen in emission in long-period variables. It is probably excited by flurorescence Joy 1954).
Absorption lines of ScII
Sc II lines (see for instance 4246) appear in late B-type, grow toward F-type and remain practically constant thereafter. A strong positive luminosity effect is present. The line at 5657 exhibits the same behavior. ScII also has two rather strong red lines at 6211(2) and 6306(2), which characterize late type stars (Keenan 1957).
Emission lines of ScII
In T Tau stars (Joy 1945) the line at 4246 as well as other ScII lines appear in emission.
Emission lines of higher ionization stages
The line 4823 of [ScVII] was observed in at least one recurrent nova by Joy and Swings (1945).
Behavior in non-normal stars
ScII lines tend to be strong in Bp stars of the Hg-Mn subgroup. W(4246) averages about 0.040 (Kodaira and Takada 1978). In contrast, Sc II lines tend to be weak in Ap stars of the Cr-Eu-Sr subgroup (Adelman 1973b). They are also weak in Am stars, which fact was discovered by Bidelman and further explored by Conti (1965). The average W values are smaller by about a factor of two. It must be added, however, that there exist Am stars in which Sc is of normal strength and even some stars in which Sc is strong (Cowley 1991). In delta Del stars the Sc II lines are weak (Kurtz 1976). However, Sc seems to behave normally in stars intermediate between Am stars and A-type giants (Berthet 1990).
Sc II lines are weakened by factors up to ten in F-type HB stars with regard to normal stars of the same colors (Adelman and Hill 1987). Adelman and Philip (1992a) remark that this applies to HB stars in general. Sc lines are probably variable in the blue stragglers of an old open cluster (Mathys 1991).
Sc seems to behave in a manner parallel to that of Fe in metal-weak dwarfs (Magain 1989) and in globular cluster stars (Wheeler et al. 1989). In extreme halo dwarfs Zhao and Magain (1990) found Sc to be overabundant with respect to Fe.
Strong ScII absorption lines appear in the spectra of supernovae of class II (Branch 1990).
Sc has one stable isotope, Sc45, and 14 unstable isotopes and isomers.
Sc can be produced by explosive nucleosynthesis, by Ne burning or by nuclear statistical equilibrium.
Published in "The Behavior of Chemical Elements in Stars", Carlos Jaschek and Mercedes Jaschek, 1995, Cambridge University Press.