Name/Affiliation: Andrea Dupree, N. S. Brickhouse, S. R. Cranmer (Harvard-Smithsonian CfA)
TW Hya: Insights from Time-Domain Multi-Wavelength Spectroscopy
High resolution ultraviolet, optical, and near-infrared spectra of TW Hya, the nearest accreting T Tauri star, cover a decade and reveal substantial changes in accretion and wind properties in one star. Stable absorption features in H-alpha, appear caused by an accreting column silhouetted in the stellar wind. Measurements of dynamics from the line profiles support a dipole accretion model: the free-fall velocity of material correlates inversely with the strength of the post-shock emission. Terminal outflow velocities appear to be directly related to the amount of post-shock emission, giving evidence for an accretion-driven stellar wind. Line-profiles when compared to existing models suggest that 3 elements are needed: (1) a turbulent post-shock region producing chromospheric emission; (2) an accretion-driven stellar wind; (3) infalling material.