Periodic eclipses of the young star PDS 110 discovered with WASP and KELT photometry

We report the discovery of eclipses by circumstellar disc material associated with the young star PDS 110 in the Ori OB1a association using the SuperWASP and Kilodegree Extremely Little Telescope surveys. PDS 110 (HD 290380, IRAS 05209-0107) is a rare Fe/Ge-type star, an ∼10 Myr-old accreting intermediate-mass star showing strong infrared excess (L_IR/L_bol ≃ 0.25). Two extremely similar eclipses with a depth of 30 per cent and duration ∼25 d were observed in 2008 November and 2011 January. We interpret the eclipses as caused by the same structure with an orbital period of 808 ± 2 d. Shearing over a single orbit rules out diffuse dust clumps as the cause, favouring the hypothesis of a companion at ∼2 au. The characteristics of the eclipses are consistent with transits by an unseen low-mass (1.8-70 M_Jup) planet or brown dwarf with a circumsecondary disc of diameter ∼0.3 au. The next eclipse event is predicted to take place in 2017 September and could be monitored by amateur and professional observatories across the world.