The Prominent Dust Emission Feature near 8.9 μm in Four H<scp>ii</scp>Regions

Peeters, E.; Tielens, A. G. G. M.; Boogert, A. C. A.; Hayward, T. L.; Allamandola, Louis J.

doi:10.1086/427143

Cited by 14 publications

(9 citation statements)

References 81 publications

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“…In the ionized medium, due to the proximity of the ionized gas with UV sources such as O and B stars and the cumulative effect of shock fronts, changes in the optical dust properties are indeed expected. For instance, depletion of PAHs has been observed toward individual HII regions (Everett & Churchwell 2010;Watson et al 2009;Contursi et al 2007;Peeters et al 2005;Povich et al 2007). However, this phenomenon does not appear to be systematic, and its origin is still poorly understood.…”

Section: Introductionmentioning

confidence: 99%

SPITZERCHARACTERIZATION OF DUST IN THE IONIZED MEDIUM OF THE LARGE MAGELLANIC CLOUD

Paradis

Paladini

Noriega-Crespo

et al. 2011

ApJ

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A systematic investigation of dust emission associated with the ionized gas has so far been performed only in our Galaxy and for wavelengths longer than 60 µm. Newly available Spitzer data now offer the opportunity to carry out a similar analysis in the Large Magellanic Cloud (LMC).By cross-correlating Spitzer SAGE (Surveying the Agents of a Galaxy's Evolution) data with the ATCA/Parkes HI 21-cm data, the NANTEN 12 CO (J=1-0) data, and both the SHASSA Hα and the Parkes 6-cm data, we investigate the physical properties of dust associated with the different phases of the gas (atomic, molecular and ionized). In particular, we study the presence and nature of dust from 3.6 to 160 µm and for various regimes of the ionized gas, spanning emission measures (EM) from ∼ 1 pc cm −6 (diffuse component) to ∼ 10 3 pc cm −6 (HII regions).Using a dust emission model, and testing our results with several radiation field spectra, we show that dust in the ionized gas is warmer than dust associated with other phases (atomic and molecular). We also find a decrease of the polycyclic aromatic hydrocarbons (PAH) relative abundance with respect to big grains (BGs), as well as an increase of the near infrared (NIR) continuum. These three results (e.g. warmer temperature, decrease of PAH abundance and increase of the NIR continuum) are found consistently for all regimes of the ionized gas. On the contrary, the molecular phase appears to provide favorable conditions for the survival of PAHs. Furthermore, the very small grain (VSG) relative abundance tends to increase in the ionized phase, especially in bright HII regions. Last but not least, our analysis shows that the emissivity of dust associated with the ionized gas is lower in the LMC than in our Galaxy, and that this difference is not accounted for by the lower metallicity of the LMC.

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Section: Introductionmentioning

confidence: 99%

SPITZERCHARACTERIZATION OF DUST IN THE IONIZED MEDIUM OF THE LARGE MAGELLANIC CLOUD

Paradis

Paladini

Noriega-Crespo

et al. 2011

ApJ

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“…Detailed analysis reveals the feature having a profile peaking at 8.9 µm with a FWHM ∼1 µm and likely not being related to PAH emission (Peeters et al, 2005).…”

Section: Pahs and Dustmentioning

confidence: 97%

“…(1) A very strong, broad 8.6 µm band is detected towards the M17-SW H II region and three compact H II regions, clearly distinct from the "classical" 8.6 µm PAH band and originating inside the H II regions (Roelfsema et al, 1996;Cesarsky et al, 1996;Verstraete et al, 1996;Peeters et al, 2002a;Peeters et al, 2005). Detailed analysis reveals the feature having a profile peaking at 8.9 µm with a FWHM ∼1 µm and likely not being related to PAH emission (Peeters et al, 2005).…”

Section: Pahs and Dustmentioning

confidence: 99%

High Excitation ISM and Gas

Peeters¹,

Martín-Hernández²,

Rodriguez‐fernandez³

et al. 2005

Space Sci Rev

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“…Detailed analysis reveals the feature having a profile peaking at 8.9 µm with a FWHM ∼1 µm and likely not being related to PAH emission (Peeters et al, 2004d).…”

Section: Pahs and Dustmentioning

confidence: 97%

“…ISO also increased the number of H ii regions showing silicate in emission (Cesarsky et al, 2000;Peeters et al, 2002b;Peeters, 2002) and detected several new dust features : 1) A very strong, broad 8.6 µm band is detected towards the M17-SW H ii region and 3 compact H ii regions, clearly distinct from the "classical" 8.6 µm PAH band and originating inside the H ii regions (Roelfsema et al, 1996;Cesarsky et al, 1996;Verstraete et al, 1996;Peeters et al, 2002a;Peeters et al, 2004d). Detailed analysis reveals the feature having a profile peaking at 8.9 µm with a FWHM ∼1 µm and likely not being related to PAH emission (Peeters et al, 2004d).…”

Section: Pahs and Dustmentioning

confidence: 99%