A Time Domain Study of X-Ray Emission from TW Hya

In the magnetospheric accretion model for T-Tauri stars, a shock is expected to form on the stellar surface when matter lifted from the disk free-falls onto the star following magnetic field lines. Observations of T-Tauri stars have broadly supported this picture, where the X-ray emission of a young star could be modeled with two components. One of them corresponding to emission from coronal gas with temperature T ~ 1e7 K and electron density n_e < 1e10 cm^-3. The other component corresponds to a cooler denser plasma (T ~ few x 1e6 K; n_e ~ 1e11 – 1e12 cm-3) and it has been attributed to the accretion shock. In order to study the nature of the X-ray emission from T-Tauri objects, we have undertaken a program to study the temporal evolution of the accretion flow on the archetypal T-Tauri star - TW Hya - with Nicer. Herein, we will present the results of this program and discuss them in the context of the nature of the accretion flow onto T-Tauri stars.