  Accretion of interplanetary dust onto gas giant exoplanets is considered.
Poynting-Robertson drag causes dust particles from distant reservoirs to slowly
inspiral toward the star. Orbital simulations for the three-body system of the
star, planet, and dust particle show that a significant fraction of the dust
may accrete onto massive planets in close orbits. The deceleration of the
supersonic dust in the planet's atmosphere is modeled, including ablation by
thermal evaporation and sputtering. The fraction of the accreted dust mass
deposited as gas-phase atoms is found to be large for close-in orbits and
massive planets. If mass outflow and vertical mixing are sufficiently weak, the
accreted dust produces a constant mixing ratio of atoms and remnant dust grains
below the stopping layer. When vertical mixing is included along with settling,
the solutions interpolate between the mixing ratio due to the meteoric source
above the homopause, and that of the well-mixed deeper atmosphere below the
homopause. The line opacity from atoms and continuum opacity from remnant dust
may be observable in transmission spectra for sufficiently large dust accretion
rates, a grain size distribution tilted toward the blowout size, and
sufficiently weak vertical mixing. If mixing is strong, the meteoric source may
still act to augment heavy elements mixed up from the deep atmosphere as well
as provide nucleation sites for the formation of larger particles. The possible
role of the Lorentz drag force in limiting the flow speeds and mixing
coefficient for pressures $\la 1\, \rm mbar$ is discussed.
