Infrared maps of W3 from 4.9 microns to 20 microns

Hackwell, J. A.; Gehrz, R. D.; Smith, J. R.; Briotta, D. A.

doi:10.1086/156082

Cited by 15 publications

(7 citation statements)

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“…They also proposed several mechanisms whereby the dust may be depleted, such as by radiation pressure from the central star or by sputtering by energetic particles. Hackwell et al (1978) came to a similar conclusion of significant dust depletion for W3 IRS1, as did Aitken, Griffiths & Jones (1977) for G333.6-0.2, on the basis of MIR emission and colour temperature maps, which are similar in nature to our images of RCW 38. More recently, detailed models (e.g.…”

Section: Dust Heating Due To Trapped Lya Photonssupporting

confidence: 89%

Mid-infrared imaging and spectroscopy of the southern Hii region RCW 38

Smith

Bourke

Wright

et al. 1999

Monthly Notices of the Royal Astronomical Society

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We present mid‐infrared images and an 8‐‐13 μ m spectrum of the southern HII region RCW 38. We determine the dust colour temperature from both our spectrum and images at 10 and 20 μ m, and deduce the gas excitation from an image in the [SIV] fine‐structure line, as well as spectra of the [ArIII], [SIV] and [NeII] fine‐structure lines. Our observations are consistent with a complex of sources associated with the RCW 38 IRS1 region, which represent knots of material in a shell, or ridge, surrounding a cavity of about 0.1 pc in radius, which is itself created by the stellar wind of the hot young source IRS2. The dust temperature does not peak closest to IRS2, but rather along the centre of the ridge, and is remarkably uniform over the extent of our image. From photoionization models for the observed line ratios at IRS1 we deduce a stellar effective temperature and gas density of about 43 000‐‐48 000 K and 104 cm‐3 respectively. Whilst the star, or star cluster, IRS2 is ultimately responsible for the observed thermal and ionic emission, the relatively uniform dust temperature implies that the bulk of the dust heating in the region is provided by resonantly trapped Lyman α photons, rather than direct stellar photons. This then also implies that the dust is depleted with respect to the gas by a factor of at least 100 from its normal interstellar value. The small‐scale spatial variations in the continuum emission and temperature can be explained by changes in the density and/or gas‐to‐dust mass ratio.

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Section: Dust Heating Due To Trapped Lya Photonssupporting

confidence: 89%

Mid-infrared imaging and spectroscopy of the southern Hii region RCW 38

Smith

Bourke

Wright

et al. 1999

Monthly Notices of the Royal Astronomical Society

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“…These points are much lower than either the molecular cloud or ISM trends. The three sources mentioned all have higher values of τ 9.8 shown in the literature (e.g., Hackwell et al 1978 for IRAS 02219+6152) however, there is very little trace of absorption in the ISO-SWS spectra.…”

Section: Comparisons Between Extinction Mapsmentioning

confidence: 67%

Extinction and Polycyclic Aromatic Hydrocarbon Intensity Variations Across the H Ii Region Iras 12063–6259

Stock

Peeters

Tielens

et al. 2013

ApJ

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The spatial variations in polycyclic aromatic hydrocarbon (PAH) band intensities are normally attributed to the physical conditions of the emitting PAHs, however in recent years it has been suggested that such variations are caused mainly by extinction. To resolve this question, we have obtained near-infrared (NIR), mid-infrared (MIR), and radio observations of the compact H ii region IRAS 12063−6259. We use these data to construct multiple independent extinction maps and also to measure the main PAH features (6.2, 7.7, 8.6, and 11.2 μm) in the MIR. Three extinction maps are derived: the first using the NIR hydrogen lines and case B recombination theory; the second combining the NIR data with radio data; and the third making use of the Spitzer/IRS MIR observations to measure the 9.8 μm silicate absorption feature using the Spoon method and PAHFIT (as the depth of this feature can be related to overall extinction). The silicate absorption over the bright, southern component of IRAS 12063−6259 is almost absent while the other methods find significant extinction. While such breakdowns of the relationship between the NIR extinction and the 9.8 μm absorption have been observed in molecular clouds, they have never been observed for H ii regions. We then compare the PAH intensity variations in the Spitzer/IRS data after dereddening to those found in the original data. It was found that in most cases, the PAH band intensity variations persist even after dereddening, implying that extinction is not the main cause of the PAH band intensity variations.

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“…We attribute most of this difference to the different fields of view of the instruments. The infrared maps presented by Hackwell et al (1978) show that W3:IRS5 is extended at mid-IR wavelengths and that especially when observing at the centre of the silicate band, PHT-S is expected to receive additional flux. Fig.…”

Section: Discussionmentioning

confidence: 95%

Detection of solid ammonia, methanol, and methane with ISOPHOT

Gürtler¹,

Klaas

Henning

et al. 2002

A&A

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Abstract. We report on a search for the NH 3 inversion band at 9.0 µm, the CH 4 band at 7.7 µm, and the CH 3 OH band at 9.7 µm in the spectra of 10 heavily obscured stellar objects taken with the spectrophotometer ISOPHOT-S aboard the Infrared Space Observatory (ISO). Four of them show indications of the NH 3 inversion band at 9.0 µm superimposed on the always strong silicate band. The results show that ammonia ice may be abundant in some cool and dense molecular circumstellar regions. The 9.7 µm band of solid CH 3 OH was detected in 5 of the sources, and also the 7.7 µm band of solid CH 4 was found in 5 sources. The PHT-S detections were cross-checked against ISO-SWS spectra from archive data. Considering the different beam sizes (24 × 24 versus 14 × 20 ), there is good agreement.

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Infrared maps of W3 from 4.9 microns to 20 microns

Cited by 15 publications

References 0 publications

Mid-infrared imaging and spectroscopy of the southern Hii region RCW 38

Mid-infrared imaging and spectroscopy of the southern Hii region RCW 38

Extinction and Polycyclic Aromatic Hydrocarbon Intensity Variations Across the H Ii Region Iras 12063–6259

Detection of solid ammonia, methanol, and methane with ISOPHOT

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