Preprint Logo P72 April
2002


To be published in:
Proc. Symp. 'New Visions of the X-ray Universe in the XMM-Newton and Chandra Era', ESA SP-488, eds. F. Jansen et al.

An XMM-Newton study of 9Sgr and the Lagoon Nebula

G. Rauw1, R. Blomme2, W.L. Waldron3, Y. Nazé1,*, T.J. Harries4, J.M. Chapman5, M.F. Corcoran6, A. Detal1, E. Gosset1,**, J.M. Pittard7, A.M.T. Pollock8, M.C. Runacres2, H. Sana1,*, I.R. Stevens9, S. Van Loo2 and J.-M. vreux1


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.

Key Words
Radiation mechanisms: non-thermal -- Stars: early-type -- Stars: individual: 9Sgr -- Stars: pre-main sequence -- X-rays: stars

Files
Article: grauw2-B1.ps.gz (365394 bytes): HTTP FTP (ftp://vela.astro.ulg.ac.be/preprints/)


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