The Coronal X-ray Spectrum of the Multiple Weak-Lined T Tauri Star System HD 98800

Abstract

We present high-resolution X-ray spectra of the multiple (hierarchical quadruple) weak-lined T Tauri star system HD 98800, obtained with the High Energy Transmission Grating Spectrograph (HETGS) on board the Chandra X-Ray Observatory. In the zeroth-order Chandra/HETGS X-ray image, both principle binary components of HD 98800 (A and B, separation 0.["]8) are detected; component A was observed to flare during the observation. The infrared excess (dust disk) component, HD 98800B, is a factor of ~4 fainter in X-rays than the apparently "diskless" HD 98800A in quiescence. The line ratios of He-like species (e.g., Ne IX and O VII) in the HD 98800A spectrum indicate that the X-ray-emitting plasma around HD 98800 is in a typical coronal density regime (log n [less than or equal to] 11). We conclude that the dominant X-ray-emitting component(s) of HD 98800 is (are) coronally active. The sharp spectral differences between HD 98800 and the classical T Tauri star TW Hya demonstrate the potential utility of high-resolution X-ray spectroscopy in providing diagnostics of pre-main-sequence accretion processes.