ISO spectroscopy of compact HII regions in the Galaxy

Peeters, E.; Martín-Hernández, N. L.; Damour, F; Cox, P.; Roelfsema, P. R.; Baluteau, J. P.; Tielens, A. G. G. M.; Churchwell, E.; Kessler, M. F.; Mathis, J. S.; Morisset, Charles; Schaerer, D.

doi:10.1051/0004-6361:20011516

Cited by 130 publications

(170 citation statements)

References 52 publications

(55 reference statements)

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“…Early estimates by Humphreys (1978) gave the distance to the Cassiopeia OB2 star-forming region, of which IRAS 23133+6050 is part, at 2.63 kpc. Peeters et al (2002) found a distance of 5.5 kpc using kinematical methods and ISO-SWS spectroscopy, which agrees with an earlier calculation by Fich & Blitz (1984) who found d = 5.2 ±0.9 kpc. However other authors, for example Lebrón et al (2001), adopt a smaller value of 3.1 kpc, closer to initial estimates, based on spectrophotmetric observations of associated stars as derived by Brand & Blitz (1993).…”

Section: Iras 23133+6050supporting

confidence: 90%

HerschelPACS and SPIRE spectroscopy of the photodissociation regions associated with S 106 and IRAS 23133+6050

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Wolfire

Peeters

et al. 2015

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Context. Photodissociation regions (PDRs) contain a large portion of all of the interstellar matter in galaxies. Classical examples include the boundaries between ionized regions and molecular clouds in regions of massive star-formation, marking the point where all of the photons that are energetic enough to ionize hydrogen have been absorbed. Aims. To determine the physical properties of the PDRs associated with the star-forming regions IRAS 23133+6050 and S 106 and present them in the context of other Galactic PDRs associated with massive star-forming regions. Methods. We employ Herschel PACS and SPIRE spectroscopic observations to construct a full 55-650 μm spectrum of each object from which we measure the PDR cooling lines, other fine-structure lines, CO lines, and the total far-infrared flux. These measurements (and combinations thereof) are then compared to standard PDR models. Subsequently, detailed numerical PDR models are compared to these predictions, yielding additional insight into the dominant thermal processes in the PDRs and their structures. Results. We find that the PDRs of each object are very similar and can be characterized by a two-phase PDR model with a very dense, highly UV irradiated phase (n ∼ 10 6 cm −3 , G 0 ∼ 10 5 ) interspersed within a lower density, weaker radiation field phase (n ∼ 10 4 cm −3 , G 0 ∼ 10 4 ). We employed two different numerical models to investigate the data. We first used RADEX models to fit the peak of the 12 CO ladder, which in conjunction with the properties derived, yielded a temperature of around 300 K. Subsequent numerical modeling with a full PDR model revealed that the dense phase has a filling factor of around 0.6 in both objects. The shape of the 12 CO ladder was consistent with these components, with heating dominated by grain photoelectric heating. An extra excitation component for the hightest-J lines (J > 20) is required for S 106.

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Section: Iras 23133+6050supporting

confidence: 90%

HerschelPACS and SPIRE spectroscopy of the photodissociation regions associated with S 106 and IRAS 23133+6050

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Wolfire

Peeters

et al. 2015

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“…Spectroscopy of H ii regions (Roelfsema et al 1998;Peeters et al 2002) shows that no strong nebular emission lines are present in the 24 μm band; the emission is mostly from the continuum. This emission can only be attributed to dust.…”

Section: The Extended Dust Emission At 24 μMmentioning

confidence: 99%

A gallery of bubbles

Deharveng

Schüller

Anderson

et al. 2010

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Context. This study deals with infrared bubbles, the H ii regions they enclose, and triggered massive-star formation on their borders.Aims. We attempt to determine the nature of the bubbles observed by Spitzer in the Galactic plane, mainly to establish if possible their association with massive stars. We take advantage of the very simple morphology of these objects to search for star formation triggered by H ii regions, and to estimate the importance of this mode of star formation.Methods. We consider a sample of 102 bubbles detected by Spitzer-GLIMPSE, and catalogued by Churchwell et al. (2006; hereafter CH06). We use mid-infrared and radio-continuum public data (respectively the Spitzer-GLIMPSE and -MIPSGAL surveys and the MAGPIS and VGPS surveys) to discuss their nature. We use the ATLASGAL survey at 870 μm to search for dense neutral material collected on their borders. The 870 μm data traces the distribution of cold dust, thus of the dense neutral material where stars may form. Results. We find that 86% of the bubbles contain ionized gas detected by means of its radio-continuum emission at 20-cm. Thus, most of the bubbles observed at 8.0 μm enclose H ii regions ionized by O-B2 stars. This finding differs from the earlier CH06 results (∼25% of the bubbles enclosing H ii regions). Ninety-eight percent of the bubbles exhibit 24 μm emission in their central regions. The ionized regions at the center of the 8.0 μm bubbles seem to be devoid of PAHs but contain hot dust. PAH emission at 8.0 μm is observed in the direction of the photodissociation regions surrounding the ionized gas. Among the 65 regions for which the angular resolution of the observations is high enough to resolve the spatial distribution of cold dust at 870 μm, we find that 40% are surrounded by cold dust, and that another 28% contain interacting condensations. The former are good candidates for the collect and collapse process, as they display an accumulation of dense material at their borders. The latter are good candidates for the compression of pre-existing condensations by the ionized gas. Thirteen bubbles exhibit associated ultracompact H ii regions in the direction of dust condensations adjacent to their ionization fronts. Another five show methanol masers in similar condensations. Conclusions. Our results suggest that more than a quarter of the bubbles may have triggered the formation of massive objects.Therefore, star formation triggered by H ii regions may be an important process, especially for massive-star formation.

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“…and (8 ± 1) × 10 −20 W cm −2 , respectively for the [Ar ], [S ] and [Ne ] lines (Verma et al 2003; see also Table 1) where we have adopted as uncertainties the typical ISO/SWS 1σ absolute flux accuracy (Peeters et al 2002). Line ratios between the ISO/SWS and TIMMI2 fluxes are 1.3 ± 0.3, 1.9 ± 0.1 and 5.7 ± 2.0.…”

Section: Line Fluxes Observed At Different Spatial Resolutionsmentioning

confidence: 99%

High spatial resolution mid-infrared spectroscopy of NGC 5253: The stellar content of the embedded super-star cluster

Martín-Hernández

Schaerer

Sauvage³

2004

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Abstract. We present the N-band (8-13 µm) spectrum of the hidden compact radio super-star cluster in NGC 5253, C2, obtained with TIMMI2 on the ESO 3.6 m telescope. The spectrum is characterised by a rising continuum due to warm dust, a silicate absorption and a strong [S ] line at 10.5 µm. Weaker lines of [Ar ] at 9.0 µm and [Ne ] at 12.8 µm are also present.The continuum can be modelled by an optically thick emission from hot (T d = 253 ± 1 K) dust emission extinguished by a cold foreground dust screen and a silicate absorption feature with A sil = 0.73 ± 0.05 mag. We show how the spatial scale of the observations greatly determine the mid-IR appearance of NGC 5253 and the important implications that this has on the interpretation of line fluxes in terms of the properties (age, IMF, etc.) of the embedded cluster. We have modelled the observed line fluxes towards C2 using photoionisation models with the most recent spectral energy distributions available to describe the integrated properties of the stellar cluster. The detailed dependence of the mid-IR lines on parameters such as the cluster age, upper mass cutoff and power law index of the IMF, as well as the local abundance, the presence of internal dust and the density structure is largely discussed. Strong constraints on the geometry based on high spatial resolution observations at different wavelengths -near-IR (HST and Keck), mid-IR (TIMMI2) and radio (VLA) -allows us to restrain the ionisation parameters to values log U ≥ −0.5 dex. This constraint on U leads to two possible solutions for the age and upper mass cutoff of C2: 1) a young (<4 Myr) cluster with a "non-standard" IMF having a low upper mass cutoff M up < 50 M ; and 2) a cluster of ∼5−6 Myr with a standard high upper mass cutoff (M up ∼ 100 M ). A young age of <4 Myr would agree with the lack of supernovae signatures in C2 and in case of being confirmed, would be the first indication for a "non-standard", low upper mass cutoff of the IMF for an individual massive cluster. An older age of ∼5-6 Myr would imply that it is possible to "contain" and hide such a compact cluster for a longer time that what it is generally thought. Arguments in favour and against these two scenarios are presented.The origin of the [O ] 25.9 µm emission measured by ISO and the possible presence of an intermediate mass black hole inside C2 are also addressed.

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ISO spectroscopy of compact HII regions in the Galaxy

Cited by 130 publications

References 52 publications

HerschelPACS and SPIRE spectroscopy of the photodissociation regions associated with S 106 and IRAS 23133+6050

HerschelPACS and SPIRE spectroscopy of the photodissociation regions associated with S 106 and IRAS 23133+6050

A gallery of bubbles

High spatial resolution mid-infrared spectroscopy of NGC 5253: The stellar content of the embedded super-star cluster

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