Dust entrainment in photoevaporative winds: The impact of X-rays

Abstract

X-ray- and EUV- (XEUV-) driven photoevaporative winds acting on protoplanetary disks around young T-Tauri stars may crucially impact disk evolution, affecting both gas and dust distributions. We investigate the dust entrainment in XEUV-driven photoevaporative winds and compare our results to existing MHD and EUV-only models. For an X-ray luminosity of $L_X = 2 \cdot 10^{30}\,\mathrm{erg/s}$ emitted by a $M_* = 0.7\,\mathrm{M}_\odot$ star, corresponding to a wind mass-loss rate of $\dot{M}_\mathrm{w} \simeq 2.6 \cdot 10^{-8} \,\mathrm{M_\odot/yr}$, we find dust entrainment for sizes $a_0 \lesssim 11\,\mu$m ($9\,\mu$m) from the inner $25\,$AU ($120\,$AU). This is an enhancement over dust entrainment in less vigorous EUV-driven winds with $\dot{M}_\mathrm{w} \simeq 10^{-10}\,\mathrm{M_\odot/yr}$. Our numerical model also shows deviations of dust grain trajectories from the gas streamlines even for $\mu$m-sized particles. In addition, we find a correlation between the size of the entrained grains and the maximum height they reach in the outflow.