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 $L_X=2\cdot 10^{30}erg/s$ emitted by a $M_{\ast }=0.7{\mathrm{M}}_{\odot }$ 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.

Accepted for publication in A&A. 12+6 pages, 10+9 figures