The Extremely Long Magnetic Period of Przybylski's Star

It is very probable that Przybylski's star has the longest known magnetic period of about 188 years. To determine the period we used data from the literature and our own estimates. We obtained new observations of the HD 101065 longitudinal magnetic field using the HARPS polarimeter at the ESO La Silla 3.6-m telescope in 2015-2017. The time span of available magnetic measurements is only 43 years (about 23% of the period), therefore our period estimation is very tentative. In this paper we discuss both the extremely long period and some other unique features of this very interesting star.