SIMBAD references

We have analyzed the existing X-ray spectroscopic data for the Weak-Line T Tauri star (WTTS) HD 283572, from the ROSAT, ASCA and SAX satellites. All the data sets are well fit with an absorbed two-temperature model based on collisional ionization equilibrium. Together with the Einstein data discussed in the literature, these data sets afford a 16.5 years time span, allowing to study the short- and long-term spectroscopic and photometric variability characteristics of the X-ray emission from WTT stars. The X-ray luminosity of HD 283572 appears to vary by factors of ≃2 on time scales of tens of kiloseconds, within a single observations, while its average X-ray luminosity has varied by a factor of ≃2.5 (peak-to-peak) along the 16.5yr studied here. The SAX observation also shows evidence for a short flare, with an enhancement of the X-ray luminosity by a factor of ≃4.