Przybylski's Star

Przybylski's Star (pronounced pʃᵻˈbɪlskiz or ʃᵻˈbɪlskiz), or HD 101065, is a rapidly oscillating Ap star at roughly from the Sun in the southern constellation of Centaurus. It has a unique spectrum showing over-abundances of most rare-earth elements, including some short-lived radioactive isotopes, but under-abundances of more common elements such as iron. In 1961, the Polish-Australian astronomer Antoni Przybylski discovered that this star had a peculiar spectrum that would not fit into the standard framework for stellar classification. Przybylski's observations indicated unusually low amounts of iron and nickel in the star's spectrum, but higher amounts of unusual elements like strontium, holmium, niobium, scandium, yttrium, caesium, neodymium, praseodymium, thorium, ytterbium and uranium. In fact, at first Przybylski doubted that iron was present in the spectrum at all. Modern work shows that the iron group elements are somewhat below normal in abundance, but it is clear that the lanthanides and other exotic elements are highly over-abundant. Przybylski's Star possibly also contains many different short-lived actinide elements with actinium, protactinium, neptunium, plutonium, americium, curium, berkelium, californium, and einsteinium being theoretically detected. The longest-lived known isotope of einsteinium has a half-life of only 472 days, with astrophysicist Stephane Goriely at the Free University of Brussels (ULB) stating (in 2017) that the evidence for such actinides is not strong as “Przybylski’s stellar atmosphere is highly magnetic, stratified and chemically peculiar, so that the interpretation of its spectrum remains extremely complex [and] the presence of such nuclei remains to be confirmed.” As well, the lead author of the actinide studies, Vera F. Gopka, directly admits that "the position of lines of the radioactive elements under search were simply visualized in synthetic spectrum as vertical markers because there are no atomic data for these lines except for their wavelengths (Sansonetti et al.