2004ApJ...609..925A

We present an analysis of the Chandra High Energy Transmission Grating Spectrometer observation of the rapidly rotating (P_rot=0.94days) post-T Tauri (∼20 Myr old) star PZ Telescopii, in the Tucana association. Using two different methods, we have derived the coronal emission measure distribution EM(T) and chemical abundances. The EM(T) peaks at logT=6.9 and exhibits a significant emission measure at temperatures logT>7. The coronal abundances are generally ∼0.5 times the solar photospheric values, which are presumed fairly representative of the composition of the underlying star. A minimum in abundance is seen at a first ionization potential (FIP) of 7-8 eV, with evidence for higher abundances at both lower and higher FIP, similar to patterns seen in other active stars. From an analysis of the He-like triplet of Mg XI, we have estimated electron densities of ∼10¹²-10¹³/cm3. All the coronal properties found for PZ Tel are much more similar to those of AB Dor, which is slightly older than PZ Tel, than to those of the younger T Tauri star TW Hya. These results support earlier conclusions that the soft X-ray emission of TW Hya is likely dominated by accretion activity rather than by a magnetically heated corona. Our results also suggest that the coronae of pre-main-sequence stars rapidly become similar to those of older active main-sequence stars soon after the accretion stage has ended.