Dispersal of Protoplanetary Disks by Central Wind Stripping

We present a model for the dispersal of protoplanetary disks by winds from either the central star or the inner disk. These winds obliquely strike the flaring disk surface and strip away disk material by entraining it in an outward radial-moving flow at the wind-disk interface which lies several disk scale heights above the mid-plane. The disk dispersal time depends on the entrainment velocity, vd = cs, at which disk material flows into this turbulent shear layer interface, where is a scale factor and cs is the local sound speed in the disk surface just below the entrainment layer. If ∼ 0.1, a likely upper limit, the dispersal time at 1 AU is ∼ 6 Myr for a disk with a surface density of 10 g cm−2, a solar mass central star, and a wind with an outflow rate Ṁw = 10−8 M yr−1 and terminal velocity vw = 200 km s−1. When compared to photoevaporation and viscous evolution, wind stripping can be a dominant mechanism only for the combination of low accretion rates (. 10−8 M yr−1) and wind outflow rates approaching these accretion rates. This case is unusual since generally outflow rates are . 0.1 of accretion rates. Subject headings: planetary systems: protoplanetary disks — stars: winds, outflows — hydrodynamics — accretion, accretion disks