P72	April 2002

¹ Institut d'Astrophysique et de Géophysique - Université de Liège, Allée du 6 Août, Bât B5c, B-4000 Liège (Sart Tilman), Belgium
² Royal Observatory Belgium, Avenue Circulaire 3, B-1180 Brussels, Belgium
³ Emergent Technology Services, Space Sciences Sector, 1801 McCormick Drive, Suite 170, Largo, MD 20774, USA
⁴ School of Physics, University of Exeter, Stocker Road, Exeter EX4 4QL, United Kingdom
⁵ Anglo-Australian Observatory, P.O. Box 296 and Australia Telescope National Facility, P.O. Box 76, Epping, NSW 2121, Australia
⁶ USRA/HEASARC Goddard Space Flight Center, Greenbelt, MD 20771, USA
⁷ Department of Physics & Astronomy, University of Leeds, Leeds LS2 9JT, United Kingdom
⁸ Computer & Scientific Co. Ltd., 230 Graham Road, Sheffield S10 3GS, United Kingdom
⁹ School of Physics & Astronomy, University of Birmingham, Edgbaston Birmingham B15 2TT, United Kingdom

^* Research Fellow FNRS, Belgium
^** Research Associate FNRS, Belgium

Abstract

     We report preliminary results of an XMM-Newton observation of the O4 V star 9Sgr (= HD164794). 9Sgr is one of a few single OB stars that display a non-thermal radio emission attributed to synchrotron emission by relativistic electrons. Inverse Compton scattering of photospheric UV photons by these relativistic electrons is a priori expected to generate a non-thermal power-law tail in the X-ray spectrum. Our EPIC and RGS spectra of 9Sgr suggest a more complex situation than expected from this 'simple' theoretical picture.
Furthermore, soft-band EPIC images of the region around 9Sgr reveal a number of point sources inside the Lagoon Nebula (M8). Most of these sources have optical counterparts inside the very young open cluster NGC6530 and several X-ray sources are associated with low and intermediate mass pre-main sequence stars. Finally, we also detect (probably) diffuse X-ray emission from the Hourglass Region that might reveal a hot bubble blown by the stellar wind of Herschel36, the ionizing star of the HG region.