Turbulence‐driven Polar Winds from T Tauri Stars Energized by Magnetospheric Accretion

Abstract

Pre-main-sequence stars are observed to be surrounded by both accretion flows and some kind of wind or jetlike outflow. Recent work by Matt and Pudritz has suggested that if classical T Tauri stars exhibit stellar winds with masslossratesabout0.1timestheiraccretionrates,the windcan carry awayenoughangularmomentumto keep thestars frombeingspunupunrealisticallybyaccretion.Thispaperpresentsapreliminarysetof theoreticalmodelsofaccretiondriven winds from the polar regions of T Tauri stars. These models are based on recently published self-consistent simulations of the Sun’s coronal heating and wind acceleration. In addition to the convection-driven MHD turbulence (which dominates in the solar case), we add another source of wave energy at the photosphere that is driven by the impact of plasma in neighboring flux tubes undergoing magnetospheric accretion. This added energy, determined quantitatively from the far-field theory of MHD wave generation, is sufficient to produce T TauriYlike mass-loss rates of at least 0.01 times the accretion rate. While still about an order of magnitude below the level required for efficient angular momentum removal, these are thefirst self-consistent models of T Tauri winds that agree reasonably