HD108: the mystery deepens with XMM-Newton observations
  In 2001, using a large spectroscopic dataset from an extensive monitoring campaign, we discovered that the peculiar Of star HD108 displayed spectacular line variations. This strange behaviour could be attributed to a variety of models, and an investigation of the high energy properties of HD108 was crucially needed to test the predictions from these models. Our dedicated XMM-Newton observation of HD108 shows that its spectrum is well represented by a two temperature thermal plasma model with kT_1\sim0.2 keV and kT_2sim1.4 keV. In addition, we find that the star does not display any significant short-term changes during the XMM-Newton exposure. Compared to previous Einstein and ROSAT detections, it also appears that HD108 does not present long-term flux variations either. While the dramatic line variations continue to modify HD108's spectrum in the optical domain, the X-ray emission of the star appears thus surprisingly stable: no simple model is for the moment able to explain such an unexpected behaviour.   Thanks to its high sensitivity, the XMM-Newton observatory has also enabled the serendipitous discovery of 57 new X-ray sources in the field of HD108. Their properties are also discussed in this paper. 
Y. Naze, G. Rauw, J.M. Vreux and M. De Becker (Institut   d'Astrophysique et de Geophysique, Liege, Belgium)