Session 6. Intergalactic and Interstellar Media III
Poster, Sunday-Wednesday, March 23, 2003, Duration of Meeting

## [6.03] Chandra/ACIS Observations of M 17, the Omega Nebula

L. Townsley, E. Feigelson (PSU), T. Montmerle (Centre d'Etudes de Saclay), P. Broos (PSU), Y.-H. Chu (UIUC), G. Garmire (PSU)

We present the first high-spatial-resolution X-ray images of the Omega Nebula (M 17), obtained in a 40-ksec Chandra/ACIS observation. NGC 6618, the massive cluster powering this H II region, is resolved at the arcsecond level into >900 stellar sources similar to those seen in closer young stellar clusters. However, we also detect soft diffuse X-ray emission on parsec scales that is spatially and spectrally distinct from the point source population. The diffuse emission has luminosity Lx ~3.4 \times 1033 ergs s-1, with plasma energy components at kT ~0.13 and ~0.6 keV (1.5 and 7 MK). This extended emission most likely arises from the fast O-star winds thermalized either by wind-wind collisions or by a termination shock against the surrounding media. We establish that only a small portion of the wind energy and mass appears in the observed diffuse X-ray plasma; we suspect that most of it flows without cooling into the low-density interstellar medium. These data provide compelling observational evidence that strong wind shocks are present in H II regions.

Support for this effort was provided by NASA contract NAS8-38252 to Gordon Garmire, the ACIS Principal Investigator.

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Bulletin of the American Astronomical Society, 35#2
© 2003. The American Astronomical Soceity.