1994A&A...292..152Z

We have observed 14 Herbig Ae/Be stars in X-rays with the ROSAT PSPC (0.1-2.4keV). In addition, we obtained data from the ROSAT archive for 7 Herbig Ae/Be stars. As a result, 11 of the 21 Herbig Ae/Be stars studied here have been detected as X-ray sources, among them AB Aur, HR 5999/6000, and Z CMa. This is surprising, since Ae/Be stars, being predominantly radiative, are unlikely to sustain dynamo magnetic fields and coronal heating. We have investigated possible correlations between the X-ray luminosity and other stellar parameters like L_bol, spectral type, stellar rotation and winds. We suspect that the origin of the X-ray emission is likely to be related to the stellar wind, although other explanations (e.g. unresolved T Tauri companions) are also discussed. Some Ae/Be stars are known to be the exciting sources of high-velocity jets, but none of the jets themselves were detected in X-rays. In several cases, the X-ray images revealed a small cluster of sources, presumably lower mass pre-main-sequence objects that surround the more massive Ae/Be stars.