Przybylski's Star
Przybylski's Star (pronounced or ), or HD 101065, is a rapidly oscillating Ap star at roughly from the Sun in the southern constellation of Centaurus. Scientific history. 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 also contains many different short-lived actinide elements with actinium, protactinium, neptunium, plutonium, americium, curium, berkelium, californium, and einsteinium being detected. The longest-lived isotope of einsteinium has a half-life of only 472 days. Other radioactive elements identified in this star include technetium and promethium. Compared to neighboring stars, HD 101065 has a high peculiar velocity of . Hypotheses. Because of  the odd properties of this star, there are numerous hypotheses about why the oddities occur. One such theory is that the star contains some long-lived nuclides from the island of stability (such as Fl or 120) and that the observed short-lived actinides are the daughters of these progenitors, occurring in secular equilibrium with their parents. Properties. HD 101065 is the prototype star of the rapidly oscillating Ap star (roAP) variable star class. In 1978, it was discovered to pulsate photometrically with a period of 12.15 min. A potential companion had also been detected, a 14th-magnitude star (in  infrared) 8 arc seconds away. This could have meant a separation of just (0.02 light-years); however, Gaia Data Release 2 suggests that while those two stars appear to us as separated by a very close angle, the actual distance separating us from this second star is light-years which means more than twice further away than Przybylski's Star.