Analysis of the variability properties of the stars in the PLATO Input Catalogue

PLATO (PLAnetary Transits and Oscillations of stars) is the European Space Agency (ESA)’s mission scheduled for 2026 with the core goal to find and characterize rocky planets in the habitable zone of solar-like stars. In the first public release of the all-sky PLATO Input Catalogue (asPIC1.1) the stellar samples optimised for the mission’s scientific requirements have been defined and they include M dwarfs and FGK dwarf and subgiant target stars. The final observing strategy will be settled two years before launch; the optimal PLATO sky fields will be those that maximize the number of the most suitable targets for the detection of transiting exoplanets. This work aims to evaluate the variability (intrinsic and extrinsic) of PLATO targets, in order to characterize them before the final sky fields and targets selection. We exploited the largest whole-sky variability analysis to date based on coherent photometric, astrometric, and spectroscopic data from the third data release of ESA’s Gaia mission, Gaia DR3. We cross-matched by the unique identifier source_id all the PIC sources included in two wide sky regions at ecliptic latitudes |β| > 38◦, which envelope every allowed choice of the PLATO sky fields, with the Gaia DR3 variable sources categorized into 11 specific classes. From this operation it resulted that the sources included in the considered sub-samples from the PLATO Input Catalogue can be distinguished into the following variability types: planetary transits hosts, short-timescale variables, eclipsing binaries, solar-like stars, upper Main Sequence oscillators, RR Lyrae stars, Cepheids and long period variables. Their properties have been investigated and the light-curves for exemplary sources from each variability class have been extracted, showing the pulsating, rotating or binary nature of the targets. We furthermore focused on the relevance of these sources for the PLATO space mission (in relation to both the primary objectives and the complementary science) and for future research prospects.