2007ApJ...660..346P -
Astrophys. J., 660, 346-362 (2007/May-1)
A multiwavelength study of M17: the spectral energy distribution and PAH emission morphology of a massive star formation region.
POVICH M.S., STONE J.M., CHURCHWELL E., ZWEIBEL E.G., WOLFIRE M.G., BABLER B.L., INDEBETOUW R., MEADE M.R. and WHITNEY B.A.
Abstract (from CDS):
We combine diffuse emission photometry from GLIMPSE and several other Galactic plane surveys covering near-IR through radio wavelengths to synthesize a global spectral energy distribution (SED) for the M17 complex. By balancing the integrated flux in the SED with the total bolometric luminosity of all known O and early B stars in the ionizing cluster, we estimate a distance to M17 of 1.6+0.3–0.1kpc. At this distance, the observed total flux in the SED corresponds to a luminosity of 2.4±0.3x106 L☉. We find that the SED from the H II region peaks at shorter wavelengths and has a qualitatively different shape than the SED from the photodissociation region (PDR). We find that polycyclic aromatic hydrocarbons (PAHs) are destroyed over a short distance or edge at the boundary of the H II region. We demonstrate that this PAH destruction edge can be located easily using GLIMPSE band-ratio images and confirm this using Spitzer IRS spectra. We investigate the relative roles of extreme ultraviolet (EUV) and X-ray photons in the destruction of PAHs, concluding that X-rays are not an important PAH destruction mechanism in M17 or, by extension, in any other Galactic H II region. Our results support the hypothesis that PAHs are destroyed by EUV photons within H II regions. PAHs dominate the mid-IR emission in the neutral PDR beyond the ionized gas.
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Journal keyword(s):
ISM: Dust, Extinction - ISM: H II Regions - Infrared: ISM - Radio Continuum: ISM - Stars: Formation - X-Rays: ISM
Simbad objects:
19
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