Can planet formation explain the observed differences in the chemical composition of binary stars?

Sammanfattning: A suggested explanation for the observed differences in chemical abundances in binary stars has been planet formation (e.g. Tucci Maia et al. 2014). If a star hosts a planet, the planet may have depleted the protoplanetary disc in volatiles and refractories. Assuming that the star accretes the remaining protoplanetary disc (neglecting photoevaporation), the depletion of the disc may alter the chemical composition of the star (post-protoplanetary disc-phase). We extend the Bitsch et al. (2015a)-disc model to include chemical species like CO, CO_2 ,H_2O, carbon grains and MgSiO_3. The mass of these molecules accreted by the planet is subtracted from the disc, altering the composition of the disc and consequently the final stellar abundance. The change in stellar abundance is calculated, using solar abundance as reference. By simluations of gas giants and super Earths we are able to get some indications on how the initial formation position and accretion of the planet alters the stellar abundance. For the super Earth we see a trend of ∆[Si/H]/∆[O/H] > 3 if the planet forms within the water ice line. We also try to reproduce the observations of the 16 Cygni system (Tucci Maia et al. 2014) where the B component is observed to host a planet. We also investigate the sensitivity of the dust to pebble ratio and the α-viscosity in the disc, using the Ida et al. (2016)-disc model for the viscosity. Using Ida et al. provides an example on how the results depend on the disc model. We are able to reproduce the observations of ∆[O/H] and ∆[Si/H], and our results indicate that the 16 Cygni Bb planet has underwent scattering to arrive to its current position.