Massive Protostars in the Infrared Dark Cloud MSXDC G034.43+00.24

Rathborne, J. M.; Jackson, J. M.; Chambers, E. T.; Simon, R.; Shipman, R.; Frieswijk, W.

doi:10.1086/491656

Cited by 123 publications

(182 citation statements)

References 25 publications

(30 reference statements)

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“…(13) The distance of N62 is uncertain. Rathborne et al (2005) assumed that the nearby IRDC, adjacent to N62 and containing the G34.4+0.2 UC H ii region, is at the near kinematical distance; A&B put the UC H ii region at the far distance, but their confidence parameter is not good. (14) N81 is a large and faint bubble.…”

Section: Appendix A: the Distance To The Bubblesmentioning

confidence: 99%

A gallery of bubbles

Deharveng

Schüller

Anderson

et al. 2010

A&A

358

584

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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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Section: Appendix A: the Distance To The Bubblesmentioning

confidence: 99%

A gallery of bubbles

Deharveng

Schüller

Anderson

et al. 2010

A&A

358

584

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“…Their sizes (∼2 pc) and masses (∼10 2 -10 4 M ) are similar to those of cluster-forming molecular clumps. This, together with the cold temperatures and fragmented substructure of IRDCs, suggests that they are protoclusters (Rathborne et al , 2005. Kinematic distances to IRDC samples in the first and fourth Galactic quadrants have been determined using 13 CO (1−0) and CS (2−1) emission (Jackson et al , 2008.…”

Section: Introductionmentioning

confidence: 96%

Ammonia from cold high-mass clumps discovered in the inner Galactic disk by the ATLASGAL survey

Wienen

Wyrowski

Schüller

et al. 2012

A&A

213

368

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Context. The APEX Telescope Large Area Survey: the GALaxy (ATLASGAL) is an unbiased continuum survey of the inner Galactic disk at 870 μm. It covers ±60 • in Galactic longitude and aims to find all massive clumps at various stages of high-mass star formation in the inner Galaxy, particularly the earliest evolutionary phases. Aims. We aim to determine properties such as the gas kinetic temperature and dynamics of new massive cold clumps found by ATLASGAL. Most importantly, we derived their kinematical distances from the measured line velocities. Methods. We observed the ammonia (J, K) = (1, 1) to (3, 3) inversion transitions toward 862 clumps of a flux-limited sample of submm clumps detected by ATLASGAL and extracted 13 CO (1−0) spectra from the Galactic Ring Survey (GRS). We determined distances for a subsample located at the tangential points (71 sources) and for 277 clumps whose near/far distance ambiguity is resolved. Results. Most ATLASGAL clumps are cold with rotational temperatures from 10−30 K with a median of 17 K. They have a wide range of NH 3 linewidths (1−7 km s −1 ) with 1.9 km s −1 as median, which by far exceeds the thermal linewidth, as well as a broad distribution of high column densities from 10 14 to 10 16 cm −2 (median of 2 × 10 15 cm −2 ) with an NH 3 abundance in the range of 5 to 30 × 10 −8 . ATLASGAL sources are massive, > ∼ 100 M , and a fraction of clumps with a broad linewidth is in virial equilibrium. We found an enhancement of clumps at Galactocentric radii of 4.5 and 6 kpc. The comparison of the NH 3 lines as high-density probes with the GRS 13 CO emission as low-density envelope tracer yields broader linewidths for 13 CO than for NH 3 . The small differences in derived clump velocities between NH 3 (representing dense core material) and 13 CO (representing more diffuse molecular cloud gas) suggests that the cores are essentially at rest relative to the surrounding giant molecular cloud. Conclusions. The high detection rate (87%) confirms ammonia as an excellent probe of the molecular content of the massive, cold clumps revealed by ATLASGAL. A clear trend of increasing rotational temperatures and linewidths with evolutionary stage is seen for source samples ranging from 24 μm dark clumps to clumps with embedded HII regions. The survey provides the largest ammonia sample of high-mass star forming clumps and thus presents an important repository for the characterization of statistical properties of the clumps and the selection of subsamples for detailed, high-resolution follow-up studies.

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“…Follow ups with outflow tracers combined with sensitive Spitzer observations have however revealed active star formation in many of these cores (for e.g. Rathborne et al 2005;Pillai et al 2006b;Beuther & Steinacker 2007). A frequently used way of identifying the precluster phase has been to scan the infrared data for dark absorption features against the bright midinfrared background.…”

Section: Introductionmentioning

confidence: 99%

Probing the initial conditions of high-mass star formation

Pillai

Kauffmann

Wyrowski

et al. 2011

A&A

137

184

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Most work on high-mass star formation has focused on observations of young massive stars in protoclusters. Very little is known about the preceding stage. Here, we present a new high-resolution study of pre-protocluster regions in tracers exclusively probing the coldest and dense gas (NH 2 D). The two target regions G29.96−0.02 and G35.20−1.74 (W48) are drawn from the SCAMPS project, which searches for pre-protoclusters near known ultracompact Hii regions. We used our data to constrain the chemical, thermal, kinematic, and physical conditions (i.e., densities) in G29.96e and G35.20w. NH 3 , NH 2 D, HCO + , and continuum emission were mapped using the VLA, PdBI, and BIMA. In particular, NH 2 D is a unique tracer of cold, precluster gas at high densities, while NH 3 traces both the cold and warm gas of modest-to-high densities. In G29.96e, Spitzer images reveal two massive filaments, one of them in extinction (infrared dark cloud). Dust and line observations reveal fragmentation into multiple massive cores strung along filamentary structures. Most of these are cold (<20 K), dense (>10 5 cm −3 ) and highly deuterated ([NH 2 D/NH 3 ] > 6%). In particular, we observe very low line widths in NH 2 D (FWHM 1 km s −1 ). These are very narrow lines that are unexpected towards a region forming massive stars. Only one core in the center of each filament appears to be forming massive stars (identified by the presence of masers and massive outflows); however, it appears that only a few such stars are currently forming (i.e., just a single Spitzer source per region). These multi-wavelength, high-resolution observations of high-mass pre-protocluster regions show that the target regions are characterized by (i) turbulent Jeans fragmentation of massive clumps into cores (from a Jeans analysis); (ii) cores and clumps that are "over-bound/subvirial", i.e. turbulence is too weak to support them against collapse, meaning that (iii) some models of monolithic cloud collapse are quantitatively inconsistent with data; (iv) accretion from the core onto a massive star, which can (for observed core sizes and velocities) be sustained by accretion of envelope material onto the core, suggesting that (similar to competitive accretion scenarios) the mass reservoir for star formation is not necessarily limited to the natal core; (v) high deuteration ratios ([NH 2 D/NH 3 ] > 6%), which make the above discoveries possible; (vi) and the destruction of NH 2 D toward embedded stars.

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Massive Protostars in the Infrared Dark Cloud MSXDC G034.43+00.24

Cited by 123 publications

References 25 publications

A gallery of bubbles

A gallery of bubbles

Ammonia from cold high-mass clumps discovered in the inner Galactic disk by the ATLASGAL survey

Probing the initial conditions of high-mass star formation

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