Destroying inner planets around giant stars

A possible explanation for the lack of close-in planets around intermediate-mass subgiant and giant stars? Apparently, a combination of gas drag from the enhanced stellar wind and stronger tidal effects due to increased depth of the convection zone can cause significant inward migration and perhaps engulfment, without needing to have the star expand all the way to the planet's orbit. Maybe has interesting implications for the planet population around intermediate-mass stars.

The Orbital Evolution of Gas Giant Planets around Giant Stars