A question on Przybylski's Star Przybylski's Star is a rapidly oscillating AP star of 4 solar masses, 355 light years from earth.  It contains high levels of unusual elements like strontium, holmium, niobium, scandium, yttrium, cesium, neodymium, praseodymium, thorium, ytterbium, uranium and even plutonium.  Several of these have extremely short half lives (relatively speaking), and should have died out by now.
One hypothesis is that these are daughter products of stable nuclides occurring in secular equilibrium.
My question is... what process is there in a star to form the parent elements needed for these bizarre elements to form? Doesn't secular equilibrium require that the parent element be made as fast as it breaks down to form the daughter elements?  
Is this a property of its mass?  If so, shouldn't we see similar characteristics in a lot of other stars of this mass range?
 A: I assume that the proposal you're referring to is by Dzuba et al. 2017 (arXiv version), and that the term "secular equilibrium" comes from the Wikipedia article on Przybylski's Star, as the authors never use reference it in the paper. As I understand it, secular equilibrium doesn't require that the parent isotope be formed as quickly as it decays, but that the daughter isotope be formed as quickly as it decays - that is, the decay rate of the daughter is roughly the same as the rate at which the parent decays to the daughter. This requires no ongoing production of the parent isotopes, merely that the parent half-life be significantly longer than the daughter half-life.
Dzuba et al. propose that the parent isotopes in the island of stability were produced in supernovae and subsequently enriched the interstellar medium. At this point, they would have been incorporated into newly-forming stars, Przybylski's Star among them. The mass of a particular star would have little to no effect on the initial abundances of these heavy elements; they would be entirely determined by the composition of the local ISM. Of course, if the star's mass is low enough, it would survive for many half-lives of the parent elements, and so throughout its life their abundances would indeed change as they decay. However, the initial presence would be mass-independent.
