On the detection of the first extragalactic classical chemically peculiar stars

We report on the detection of the first extragalactic, classical chemically peculiar (CP) stars more than 100 years after the discovery of this group. Using the tool of CCD $\Delta a$-photometry, eight definite positive detections in the globular-like stellar cluster NGC 1866 and its surrounding in the Large Magellanic Cloud were made. More than 1950 objects within a radius of 9.5′ of the cluster center down to 20.5 magnitude were observed in this three filter, narrow band photometric system. Averaging more than 70 individual frames for all three filters yielded a 3σ detection limit of 0.015 mag for stars with $V=20$ mag. Furthermore we found three objects with significantly negative $\Delta a$-values indicating either an Ae/shell or λ Bootis nature. The overall percentage of chemically peculiar stars for NGC 1866 (1.5% ) seems lower than for the majority of open clusters in our Milky Way whereas the incidence within the LMC field is decisively less (0.3% ).