Possible nuclear origin of Ap and Am stars

Abstract

MANY possible mechanisms have been proposed to explain the abundance anomaly of heavy elements on Ap and Am stars. Van den Heuvel¹ suggested that these stars had been secondaries of binary systems, whose primaries exploded as supernovae and caused the accretion of heavy elements on the secondaries. The abundance distribution of elements with Z ≳ 40 in those stars is generally similar to that of r nuclei in the Solar System, although the overabundance factor for each element relative to Solar System r abundance is not constant, being exceptionally high in some limited regions such as the region around Te, the rare earth region around Nd and Sm, and around Pt and Hg. These observational trends suggest that the abundance pattern in those stars may be a superposition of some specific elements with anomalously high abundance on a background proportional to the Solar System r abundance. Here I suggest an alternative possibility for the nuclear origin of anomalous abundance in Ap and Am stars.