Evidence of triggered star formation in G327.3-0.6

Minier, V.; André, Ph.; Bergman, P.; Motte, F.; Wyrowski, F.; Pennec, J. Le; Rodriguez, L.; Boulade, O.; Doumayrou, E.; Dubreuil, Didier; Gallais, P.; Hamon, G.; Lagage, Pierre-Olivier; Lortholary, M.; Martignac, J.; Revéret, V.; Roussel, H.; Talvard, M.; Willmann, Gabriel; Olofsson, H.

doi:10.1051/0004-6361/200912308

Cited by 18 publications

(23 citation statements)

References 13 publications

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“…3.2). The submillimetre source SMM6 (seen in the continuum emission at 450 μm by Minier et al 2009) is detected as a peak of emission in all integrated intensity maps of 12 CO and in 13 CO(6-5), although at the edge of the mapped region. The other submillimetre sources are also marked in Figs.…”

Section: Morphologymentioning

confidence: 96%

The distribution of warm gas in the G327.3–0.6 massive star-forming region

Leurini

Wyrowski

Herpin

et al. 2013

A&A

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Aims. Most studies of high-mass star formation focus on massive and/or luminous clumps, but the physical properties of their larger scale environment are poorly known. In this work, we aim at characterising the effects of clustered star formation and feedback of massive stars on the surrounding medium by studying the distribution of warm gas through mid-J 12 CO and 13 CO observations. Methods. We present APEX 12 CO(6-5), (7-6), 13 CO(6-5), (8-7) and HIFI 13 CO(10-9) maps of the star forming region G327.36-0.6 with a linear size of ∼3 pc × 4 pc. We infer the physical properties of the emitting gas on large scales through a local thermodynamic equilibrium analysis, while we apply a more sophisticated large velocity gradient approach on selected positions. Results. Maps of all lines are dominated in intensity by the photon dominated region around the Hii region G327.3-0.5. Mid-J 12 CO emission is detected over the whole extent of the maps with excitation temperatures ranging from 20 K up to 80 K in the gas around the Hii region, and H 2 column densities from few 10 21 cm −2 in the inter-clump gas to 3 × 10 22 cm −2 towards the hot core G327.3-0.6. The warm gas (traced by 12 and 13 CO(6-5) emission) is only a small percentage (∼10%) of the total gas in the infrared dark cloud, while it reaches values up to ∼35% of the total gas in the ring surrounding the Hii region. The 12 CO ladders are qualitatively compatible with photon dominated region models for high density gas, but the much weaker than predicted 13 CO emission suggests that it comes from a large number of clumps along the line of sight. All lines are detected in the inter-clump gas when averaged over a large region with an equivalent radius of 50 (∼0.8 pc), implying that the mid-J 12 CO and 13 CO inter-clump emission is due to high density components with low filling factor. Finally, the detection of the 13 CO(10-9) line allows to disentangle the effects of gas temperature and gas density on the CO emission, which are degenerate in the APEX observations alone.

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Section: Morphologymentioning

confidence: 96%

The distribution of warm gas in the G327.3–0.6 massive star-forming region

Leurini

Wyrowski

Herpin

et al. 2013

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“…It has been used to identify compact sources of thermal dust emission by different groups for complex regions, such as W43 (Motte et al 2003), Cygnus-X (Motte et al 2007), and the NGC 6334−NGC 6357 complexes (Russeil et al 2010). It has also been applied for smaller regions, such as RCW 106 (Mookerjea et al 2004), NGC 2264 (Peretto et al 2006), and G327.3-0.6 (Minier et al 2009). The main steps are to first disentangle the compact sources from the more diffuse, extended emission of filamentary clouds.…”

Section: Overview Of Source Extraction Algorithmsmentioning

confidence: 99%

The ATLASGAL survey: a catalog of dust condensations in the Galactic plane

Csengeri¹,

Urquhart²,

Schüller³

et al. 2014

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Context. The formation processes and the evolutionary stages of high-mass stars are poorly understood compared to low-mass stars. Large-scale surveys are needed to provide an unbiased census of high column density sites that can potentially host precursors to high-mass stars. Aims. The ATLASGAL survey covers 420 sq. degree of the Galactic plane, between −80 • < < +60 • at 870 μm. Here we identify the population of embedded sources throughout the inner Galaxy. With this catalog we first investigate the general statistical properties of dust condensations in terms of their observed parameters, such as flux density and angular size. Then using mid-infrared surveys we aim to investigate their star formation activity and the Galactic distribution of star-forming and quiescent clumps. Our ultimate goal is to determine the statistical properties of quiescent and star-forming clumps within the Galaxy and to constrain the star formation processes. Methods. We optimized the source extraction method, referred to as MRE-GCL, for the ATLASGAL maps in order to generate a catalog of compact sources. This technique is based on multiscale filtering to remove extended emission from clouds to better determine the parameters corresponding to the embedded compact sources. In a second step we extracted the sources by fitting 2D Gaussians with the Gaussclumps algorithm. Results. We have identified in total 10861 compact submillimeter sources with fluxes above 5σ. Completeness tests show that this catalog is 97% complete above 5σ and >99% complete above 7σ. Correlating this sample of clumps with mid-infrared point source catalogs (MSX at 21.3 μm and WISE at 22 μm), we have determined a lower limit of 33% that is associated with embedded protostellar objects. We note that the proportion of clumps associated with mid-infrared sources increases with increasing flux density, achieving a rather constant fraction of ∼75% of all clumps with fluxes over 5 Jy/beam being associated with star formation. Examining the source counts as a function of Galactic longitude, we are able to identify the most prominent star-forming regions in the Galaxy. Conclusions. We present here the compact source catalog of the full ATLASGAL survey and investigate their characteristic properties. From the fraction of the likely massive quiescent clumps (∼25%), we estimate a formation time scale of ∼7.5 ± 2.5 × 10 4 yr for the deeply embedded phase before the emergence of luminous young stellar objects. Such a short duration for the formation of high-mass stars in massive clumps clearly proves that the earliest phases have to be dynamic with supersonic motions.

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“…G327.3-0.6 G327.3-0.6 has a spectacular richness of lines with relatively narrow widths (Gibb et al 2000;Schilke et al 2006). The hot core is embedded in a larger structure, where different stages of star formation take place (Wyrowski et al 2006;Minier et al 2009). Figure 4 shows the observed lines and the best-fit model (Table 8).…”

Section: Iras 16065-5158mentioning

confidence: 99%

Structure of evolved cluster-forming regions

Rolffs

Schilke

Wyrowski

et al. 2011

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Context. An approach towards understanding the formation of massive stars and star clusters is to study the structure of their hot core phase, an evolutionary stage where dust has been heated, but molecules have not yet been destroyed by ultraviolet radiation. These hot molecular cores are very line-rich, but the interpretation of line surveys is also hampered by poor knowledge of the physical and chemical structure. Aims. To constrain the radial structure of high-mass star-forming regions containing hot cores, we attempt to reproduce by radiative transfer modeling both the intensity and shape of a variety of molecular lines. Methods. We observed 12 hot cores with the Atacama Pathfinder EXperiment (APEX) in lines of HCN, HCO + , CO, and their isotopologues, including high-J lines and vibrationally excited HCN. We investigate how well the sources can be modeled as centrally heated spheres with a power-law density gradient, making use of the radiative transfer code RATRAN and the radial profile of the submm continuum emission, taken from the APEX Telescope Large Area Survey of the GALaxy (ATLASGAL). Results. Most of the observed lines have complicated shapes that incorporate self-absorption, asymmetries, and line wings. Vibrationally excited HCN is detected in all sources, and vibrationally excited H 13 CN in half of the sources. We are able to successfully model most features seen in the APEX data, such as the ratio of the isotopologue lines (very high optical depths), self-absorption (temperature gradient), blue asymmetries (moderate infall), vibrationally excited HCN (high inner temperatures), and H 13 CN (high HCN abundance under dense and hot conditions). Other features could not be reproduced, such as an occasional lack of self-absorption, the emission from high-J lines in the outer pixels of the CHAMP+ receiver (15 −20 from the center), the outflow wings, and the red asymmetric profiles. Conclusions. The amount of molecular gas, in particular of HCN, at very high temperatures is larger than previously thought. A complex interplay between infall and outflow motions is present. Our basic model assumptions of pure central heating and a power-law radial density distribution can serve as approximations for most sources, but are too simple to explain all observed lines. In particular, taking into account clumpiness, multiplicity of heating sources and a more complex velocity field seems to be necessary to more closely match model calculations to observations. This would require three-dimensional radiative transfer modeling of high-resolution interferometric data.

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Evidence of triggered star formation in G327.3-0.6

Cited by 18 publications

References 13 publications

The distribution of warm gas in the G327.3–0.6 massive star-forming region

The distribution of warm gas in the G327.3–0.6 massive star-forming region

The ATLASGAL survey: a catalog of dust condensations in the Galactic plane

Structure of evolved cluster-forming regions

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