SIMBAD references

We analyse ROSAT All-Sky Survey (RASS) observations of a ∼10³deg2 area including the Taurus-Auriga star forming region and its surroundings. The sample of low-mass pre-main sequence stars detected with the spatially complete flux-limited RASS consists mainly of weak-emission line T Tauri stars (WTTS). Two thirds of all RASS X-ray sources cannot be identified with known stellar or extragalactic counterparts. Based on the fraction of spectroscopically identified WTTS among a sample of previously unidentified RASS sources, we extrapolate a lower limit for the total number of WTTS in and around Taurus-Auriga: WTTS outnumber classical TTS by at least a factor of 8. A selection criterion for WTTS candidates is established based on the low-resolution X-ray spectra of identified WTTS. We achive a selection reliability of 54%.