Planetary migration is essential to explain the observed mass-period relation for exoplanets .
Without some stopping mechanism , the tidal , resonant interaction between planets and their gaseous disc generally causes the planets to migrate inward so efficiently that they plunge into the host star within the gaseous disc lifetime ( \sim 1-3 Myrs ) .
We investigate planetary migration by analytically calculating the migration rate and time within self-consistently computed , radiatively heated discs around M stars in which the effects of dust settling are included .
We show that dust settling lowers the disc temperature and raises the gas density in the mid-plane .
This inescapable evolution of disc structure speeds up type I planetary migration for lower mass bodies by up to a factor of about 2 .
We also examine the effects of dust settling on the gap-opening mass and type II migration , and find that the gap-opening mass is reduced by a factor of 2 and type II migration becomes slower by a factor of 2 .
While dust settling can somewhat alleviate the problem of planetary migration for more massive planets , the more rapid migration of low mass planets and planetary cores requires a robust slowing mechanism .