The circumstellar environment of high mass
 protostellar objects

Fuller, G. A.; Williams, S. J.; Sridharan, T. K.

doi:10.1051/0004-6361:20042110

Cited by 148 publications

(235 citation statements)

References 36 publications

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“…Thus we conclude that this accretion rate approximation does not affect the results too much. Observations show that star-forming clumps accrete at about 10 −3 M yr −1 with an infall velocity of around 1 km s −1 (Fuller et al 2005;Peretto et al 2006;López-Sepulcre et al 2010;Rygl et al 2013), which is consistent with our model estimation.…”

Section: Accretion Ratesupporting

confidence: 91%

Formation of a protocluster: A virialized structure from gravoturbulent collapse

Lee

Hennebelle

2016

A&A

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Context. Most stars are born in the gaseous protocluster environment where the gas is reprocessed after the global collapse from the diffuse molecular cloud. The knowledge of this intermediate step gives more accurate constraints on star formation characteristics. Aims. We demonstrate that a virialized globally supported structure, in which star formation happens, is formed out of a collapsing molecular cloud, and we derive a mapping from the parent cloud parameters to the protocluster to predict its properties with a view to confront analytical calculations with observations and simulations. Methods. We decomposed the virial theorem into two dimensions to account for the rotation and the flattened geometry. Equilibrium was found by balancing rotation, turbulence, and self-gravity, while turbulence was maintained through accretion driving and it dissipates in one crossing time. We estimated the angular momentum and the accretion rate of the protocluster from the parent cloud properties.Results. The two-dimensional virial model predicts the size and velocity dispersion given the mass of the protocluster and that of the parent cloud. The gaseous protoclusters lie on a sequence of equilibrium with the trend R ∼ M 0.5 with limited variations, depending on the evolutionary stage, parent cloud, and parameters that are not well known, such as turbulence driving efficiency by accretion and turbulence anisotropy. The model reproduces observations and simulation results successfully. Conclusions. The properties of protoclusters follow universal relations and they can be derived from that of the parent cloud. The gaseous protocluster is an important primary stage of stellar cluster formation, and should be taken into account when studying star formation. Using simple estimates to infer the peak position of the core mass function (CMF) we find a weak dependence on the cluster mass, suggesting that the physical conditions inside protoclusters may contribute to set a CMF, and by extension an initial mass function (IMF), that appears to be independent of the environment.

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Section: Accretion Ratesupporting

confidence: 91%

Formation of a protocluster: A virialized structure from gravoturbulent collapse

Lee

Hennebelle

2016

A&A

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“…Several surveys have been undertaken to search for infall of molecular gas associated with massive star formation. Among these are Fuller et al (2005), Purcell et al (2006), Klassen & Wilson (2007), and Wu et al (2007). All of these used HCO + and H 13 CO + (3−2) observations along with a few other molecular probes.…”

Section: Resultsmentioning

confidence: 99%

A millimeter survey of ultra-compact HII-regions and associated molecular clouds

Churchwell

Sievers

Thum

2010

A&A

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We report observations, using the IRAM 30 m telescope, of 30 ultracompact and hypercompact HII regions in the lines of HCO + (3−2) and/or HCO + (1−0) and H30α and/or H39α. Images are presented in both HCO + (3−2) and H30α toward a subset of regions (16 in HCO + (3−2), 14 in H30α) with a resolution of 12 . In addition, H 13 CO + (3−2) observations are reported toward 13 HII regions where HCO + (3−2) displays complex profiles. It is shown that the absorption dips in the HCO + profiles are due to HCO + self-absorption, not absorption of the HII free-free emission or warm dust emission surrounding the HII region or two velocity components along the line of sight. It was found that among the sources with self-absorbed profiles, 8 are contracting and 5 are expanding. Mass fluxes are found to be typically a few times 10 −3 M yr −1 , implying time scales for massive star formation <10 5 yrs. HCO + and H 2 column densities are estimated for a subset of the sources from which masses of the dense central cloud cores were estimated. Implications of the derived column densities, masses, flow velocities, and mass fluxes are discussed.

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“…This almost symmetric double-horn profile might be produced by the outflow (Fuller et al 2005). In reality, the absorption is seen against both the outflow and continuum emission.…”

Section: Line Asymmetriesmentioning

confidence: 92%

“…Outflows, infall, and rotation can produce very specific line profiles with characteristic signatures (see Fuller et al 2005, and references therein). Outflow and rotation give rise to both red and blue asymmetric lines, while the profiles of optically thick lines from infalling material have stronger blue-shifted emission than the redshifted emission.…”

Section: Line Asymmetriesmentioning

confidence: 99%

The massive protostar W43-MM1 as seen byHerschel-HIFI water spectra: high turbulence and accretion luminosity

Herpin

Chavarría

Tak

et al. 2012

A&A

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Aims. We present Herschel-HIFI observations of 14 water lines in W43-MM1, a massive protostellar object in the luminous starcluster-forming region W43. We place our study in the more general context of high-mass star formation. The dynamics of these regions may be represented by either the monolithic collapse of a turbulent core, or competitive accretion. Water turns out to be a particularly good tracer of the structure and kinematics of the inner regions, allowing an improved description of the physical structure of the massive protostar W43-MM1 and an estimation of the amount of water around it. Methods. We analyze the gas dynamics from the line profiles using Herschel-HIFI observations acquired as part of the Water In Star-forming regions with Herschel project of 14 far-IR water lines (H 16 2 O, H 17 2 O, H 18 2 O), CS(11-10), and C 18 O(9-8) lines, using our modeling of the continuum spectral energy distribution. The spectral modeling tools allow us to estimate outflow, infall, and turbulent velocities and molecular abundances. We compare our results to previous studies of low-, intermediate-, and other high-mass objects. Results. As for lower-mass protostellar objects, the molecular line profiles are a mix of emission and absorption, and can be decomposed into "medium" (full width at half maximum FWHM 5-10 km s −1 ), and "broad" velocity components (FWHM 20-35 km s −1 ). The broad component is the outflow associated with protostars of all masses. Our modeling shows that the remainder of the water profiles can be well-fitted by an infalling and passively heated envelope, with highly supersonic turbulence varying from 2.2 km s −1 in the inner region to 3.5 km s −1 in the outer envelope. In addition, W43-MM1 has a high accretion rate of between 4.0 × 10 −4 and 4.0 × 10 −2 M yr −1 , as derived from the fast (0.4-2.9 km s −1 ) infall observed. We estimate a lower mass limit for gaseous water of 0.11 M and total water luminosity of 1.5 L (in the 14 lines presented here). The central hot core is detected with a water abundance of 1.4 × 10 −4 , while the water abundance for the outer envelope is 8 × 10 −8 . The latter value is higher than in other sources, and most likely related to the high turbulence and the micro-shocks created by its dissipation. Conclusions. Examining the water lines of various energies, we find that the turbulent velocity increases with the distance from the center. While not in clear disagreement with the competitive accretion scenario, this behavior is predicted by the turbulent core model. Moreover, the estimated accretion rate is high enough to overcome the expected radiation pressure.

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The circumstellar environment of high mass protostellar objects

Cited by 148 publications

References 36 publications

Formation of a protocluster: A virialized structure from gravoturbulent collapse

Formation of a protocluster: A virialized structure from gravoturbulent collapse

A millimeter survey of ultra-compact HII-regions and associated molecular clouds

The massive protostar W43-MM1 as seen byHerschel-HIFI water spectra: high turbulence and accretion luminosity

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