Abstract

Contributed Talk - Splinter StarFormation   (MW-1250)

The prototypical T Tauri star TW Hya as a probe for different magnetospheric accretion regimes

J. Y. Zhang; B. Stelzer; A. Armeni; C. F. Manara; F. M. Walter; J. Campbell-White
Eberhard Karls Universität Tübingen (IAAT)

Low-mass pre-main sequence stars, called Classical T Tauri stars, accrete matter through magnetic channel flows. Depending on how the disk material interacts with the stellar magnetic field they may accrete in different magnetospheric regimes. In this talk, I will present a multi-epoch photometric and spectroscopic study of the prototypical nearby (~60pc) classical T Tauri star TW Hya, combining light curves from the Transiting Exoplanet Survey Satellite (TESS) with simultaneous high-resolution spectra obtained with CHIRON at Cerro Tololo Inter-American Observatory. Period searches in the TESS light curves show signals that differ from the known 3.56-day stellar rotation period (P_rot) found from spectroscopy in previous work. Some periods are shorter than the P_rot, similar to the unstable accretion behaviour seen in more strongly accreting systems such as RU Lup. Other periods are longer and may point to temporary propeller-like states. We use the spectra to measure mass accretion rates, estimate the inner radius where the stellar magnetic field truncates the disk, and search for signs of mass ejection during different photometric accretion states. With this approach, we test whether TW Hya switches between different accretion regimes on timescales of days to weeks. These results can be compared with MHD models of star–disk interaction. The detailed characterization of accretion in benchmark classical T Tauri stars may serve as a template for the search of accretion variability in younger protostars.