A Critical Examination of Li Pollution and Giant‐Planet Consumption by a Host Star

We examine the overall likelihood that the consumption of a giant planetcould pollute its host star. First, we show that the detection of 6Li in SWPscould be used to distinguish between giant planet formation theories, and canbe used to detect the consumption of giant planets independent of planet mass.Second, we examine the probability that giant planets between 1 and 3 M_J couldbe destroyed in the outer convection zone of stars slightly more massive thanthe Sun, finding that heated giant planets would be efficiently destroyed nearthe surface of the star, while the cores of cold giant planets may be able tosurvive to the base of the star's convection zone. Third, we examine the tidalinteraction between a planet and its host star, showing that this interactioncan lead to tidal disruption of the planet and accretion of its material, ororbital decay followed by hydrodynamical interaction. Throughout, we considerthe case of HD 82943, a star known to have two planets and having a preliminarydetection of 6Li. Using stellar models including diffusion, we estimate themass of the HD 82943 to be about 1.2 M_sun and its age to be about 0.5-1.5 Gyr.The observed 7Li abundance for HD 82943 is consistent with stars of similarT_eff and age in the open cluster NGC 752. We describe a possible dynamicalhistory for a hypothetical planet in the presence of the two resonant planetscurrently known. (abridged)Comment: 33 pages, 3 figures, accepted for Ap