Given the high metal contents observed for many stars with planets ( SWPs ) , we examine the overall likelihood that the consumption of a giant planet could pollute its host star .
First , we discuss ^ { 6 } Li and ^ { 7 } Li as indicators of pollution , verifying that ^ { 6 } Li is a strong indicator of pollution 30 Myr after star formation , and showing that it strongly constrains the amount of heavy element pollution incorporated into the star .
Detection of ^ { 6 } Li in SWPs could also be used to distinguish between giant planet formation theories , and can be 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 } could be destroyed in the outer convection zone of stars slightly more massive than the Sun ( for which detection of a chemical signature of pollution would be easiest ) .
We find that heated giant planets would be efficiently destroyed near the surface of the star , while the cores of cold giant planets may be able to survive a plunge through the base of the star ’ s convection zone .
Third , we examine whether dynamical processes could bring a giant planet close enough to the star to destroy it , and whether the destruction of a planet would necessarily affect other planets in the system .
While tidal interaction between protoplanets and their nascent disks may have led them to the proximity of their host stars , post-formation star-planet interaction can lead to tidal disruption of the planet and accretion of its material , or orbital decay followed by hydrodynamical interaction .
Throughout , we consider the case of HD 82943 , a star known to have two planets and having a preliminary detection of ^ { 6 } Li .
Using stellar models including diffusion , we estimate the mass of the HD 82943 to be \sim 1.2 M _ { \odot } and its age to be \sim 0.5 - 1.5 Gyr .
The observed ^ { 7 } Li abundance for HD 82943 is consistent with stars of similar T _ { eff } and age in the open cluster NGC 752 .
We describe a possible dynamical history for a hypothetical planet in the presence of the two resonant planets currently known .
We present stable orbital configurations in which the hypothetical planet has low eccentricity and semi-major axis near 0.02 AU , so that it is dynamically decoupled from the resonant planets .
Tidal interactions with the slowly-rotating star can subsequently drag the planet into the stellar surface within the age of the star .