An XMM-Newton view of the M17 nebula

Francois Mernier, Gregor Rauw

Institut d'Astrophysique, Liege University, Belgium

We present the analysis of an XMM-Newton observation of the M17 nebula. The
X-ray point source population consists of massive O-type stars and a population
of probable low-mass pre-main sequence stars. CEN1a,b and OI352, the X-ray
brightest O-type stars in M17, display hard spectra (kT of 3.8 and 2.6 keV)
consistent with a colliding wind origin in binary/multiple systems. We show
that the strong interstellar reddening towards the O-type stars of M17 yields
huge uncertainties on their Lx/Lbol values. The low-mass pre-main sequence
stars exhibit hard spectra resulting from a combination of high plasma
temperatures and very large interstellar absorption. We find evidence for
considerable long term (months to years) variability of these sources. M17 is
one of the few star formation complexes in our Galaxy producing diffuse X-ray
emission. We analyze the spectrum of this emission and compare it with previous
studies. Finally, we discuss the Optical Monitor UV data obtained
simultaneously with the X-ray images. We find very little correspondence
between the UV and X-ray sources, indicating that the majority of the UV
sources are foreground stars, whilst the bulk of the X-ray sources are deeply
embedded in the M17 complex.

Reference: New Astronomy
Status: Manuscript has been accepted

Weblink: arXiv:1210:2936