  Spectral lines belonging to the short-lifetime heavy radioactive elements up
to Es ($Z$=99) have been found in the spectra of the Przybylski's star. We
suggest that these unstable elements may be decay products of a "magic"
metastable nucleus belonging to the the island of stability where the nuclei
have a magic number of neutrons $N=184$. The laboratory-produced nuclei have a
significantly smaller number of neutrons. To identify spectra of the $N=184$
isotopes of these nuclei and their neutron-reach superheavy decay products in
astrophysical data we calculate the isotope shift which should be added to the
laboratory - measured wavelenghs. The results for the isotopic shifts in the
strongest optical electromagnetic transitions in No, Lr, Nh, Fl,and $Z$=120
elements are presented.
