Fragmentation and mass segregation in the massive dense cores of Cygnus X

Bontemps, Sylvain; Motte, F.; Csengeri, T.; Schneider, N.

doi:10.1051/0004-6361/200913286

Cited by 180 publications

(382 citation statements)

References 72 publications

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“…Chosen MDCs are weak at cm wavelengths (except for IRAS 05358+3543, which exhibits an UC-HII region), making them good candidates to represent an early stage of the formation of massive stars. Other studies infer a high accretion rate for these sources (∼10 −3 −10 −4 M yr −1 ) derived from the power of their molecular outflows, and a clustered formation process observed by interferometry (Zapata et al 2006;Leurini et al 2007a;Molinari et al 2008;Bontemps et al 2010). According to IRAS or MSX data, these sources emit between 0.2 and 22 Jy at 12 µm.…”

Section: Source Samplementioning

confidence: 91%

Tracing early evolutionary stages of high-mass star formation with molecular lines

Marseille

Tak

Herpin

et al. 2010

A&A

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Context. Despite its major role in the evolution of the interstellar medium, the formation of high-mass stars (M ≥ 10 M ) remains poorly understood. Two types of massive star cluster precursors, the so-called massive dense cores (MDCs), have been observed, which differ in terms of their mid-infrared brightness. The origin of this difference has not yet been established and may be the result of evolution, density, geometry differences, or a combination of these. Aims. We compare several molecular tracers of physical conditions (hot cores, shocks) observed in a sample of mid-IR weakly emitting MDCs with previous results obtained in a sample of exclusively mid-IR bright MDCs. We attempt to understand the differences between these two types of object. Methods. We present single-dish observations of HDO, H 18 2 O, SO 2 , and CH 3 OH lines at λ = 1.3−3.5 mm. We study line profiles and estimate abundances of these molecules, and use a partial correlation method to search for trends in the results.Results. The detection rates of thermal emission lines are found to be very similar for both mid-IR quiet and bright objects. The abundances of H 2 O, HDO (10 −13 to 10 −9 in the cold outer envelopes), SO 2 and CH 3 OH differ from source to source but independently of their mid-IR flux. In contrast, the methanol class I maser emission, a tracer of outflow shocks, is found to be strongly anti-correlated with the 12 µm source brightnesses. Conclusions. The enhancement of the methanol maser emission in mid-IR quiet MDCs may be indicative of a more embedded nature. Since total masses are similar between the two samples, we suggest that the matter distribution is spherical around mid-IR quiet sources but flattened around mid-IR bright ones. In contrast, water emission is associated with objects containing a hot molecular core, irrespective of their mid-IR brightness. These results indicate that the mid-IR brightness of MDCs is an indicator of their evolutionary stage.

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Section: Source Samplementioning

confidence: 91%

Tracing early evolutionary stages of high-mass star formation with molecular lines

Marseille

Tak

Herpin

et al. 2010

A&A

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“…These regions are similar in distance and luminosity to IRAS 19410+2336, and although the gas mass varies, even the regions more massive than IRAS 19410+2336 show much less fragmentation on similar spatial scales. More recently, there is the work of Bontemps et al (2010) in the Cygnus X region. They resolved 5 clumps down to spatial scales similar to the ones we obtained, recovering 23 fragments in total, from which they estimated 9 are probable high-mass protostars.…”

Section: The Cmf Of Iras 19410+2336mentioning

confidence: 99%

“…That resolution in the (sub)mm regime is only achievable with the interferometric technique. So far, only a few MSF regions have been observed in the (sub)mm with spatial resolutions good enough to resolve individual cores (e.g., Bontemps et al 2010;Fontani et al 2009;Rodón et al 2008;Rathborne et al 2008;Beuther et al 2006), and for only one source, IRAS 19410+2336, has it been possible to determine a CMF (Beuther & Schilke 2004).…”

Section: Introductionmentioning

confidence: 99%

Fragmentation in the massive star-forming region IRAS 19410+2336

Rodón

Beuther

Schilke

2012

A&A

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Context. The core mass functions (CMFs) of low-mass star-forming regions are found to resemble the shape of the initial mass function (IMF). A similar result is observed for the dust clumps in high-mass star-forming regions, although on spatial scales of clusters that do not resolve the substructure that is found in these massive clumps. The region IRAS 19410+2336 is one exception, having been observed on spatial scales on the order of ∼2500 AU, which are sufficient to resolve the clump substructure into individual cores. Aims. We investigate the protostellar content of IRAS 19410+2336 at high spatial resolution at 1.4 mm, determining the temperature structure of the region and deriving its CMF. Methods. The massive star-forming region IRAS 19410+2336 was mapped with the PdBI (BCD configurations) at 1.4 mm and 3 mm in the continuum and several transitions of formaldehyde (H 2 CO) and methyl cyanide (CH 3 CN). The H 2 CO transitions were also observed with the IRAM 30 m Telescope. Results. We detect 26 continuum sources at 1.4 mm with a spatial resolution as low as ∼2200 AU, several of them with counterparts at near-and mid-infrared wavelengths, distributed in two (proto)clusters. With the PdBI CH 3 CN and PdBI/IRAM 30 m H 2 CO emission, we derive the temperature structure of the region, ranging from 35 K to 90 K. Using these temperatures, we calculate the core masses of the detected sources, ranging from ∼0.7 M to ∼8 M . These masses are strongly affected by the spatial filtering of the interferometer, which removes a common envelope with ∼90% of the single-dish flux. Considering only the detected dense cores and accounting for binning effects as well as cumulative distributions, we derive a CMF, with a power-law index β = −2.3 ± 0.2. We resolve the Jeans length of the (proto)clusters by one order of magnitude, and only find a small velocity dispersion between the different subsources. Conclusions. Since we cannot unambiguously differentiate between protostellar and prestellar cores, the derived CMF is not prestellar. Furthermore, because of the large fraction of missing flux, we cannot establish a firm link between the CMF and the IMF. This implies that future high-mass CMF studies will need to complement the interferometer continuum data with the short spacing information, a task suitable for ALMA. We note that the method of extracting temperatures using H 2 CO lines becomes less applicable when reaching the dense core scales of the interferometric observations because most of the H 2 CO appears to originate in the envelope structure.

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“…In general, the few studies performed so far with sub-arcsecond angular resolution, or close to ∼1 , reveal either low fragmentation (e.g. Palau et al 2013;Longmore et al 2011), or many fragments that are too massive, however, to be consistent with the gravoturbulent scenario (Bontemps et al 2010;Zhang et al 2015). Furthermore, comparisons with models that assume the actual physical conditions (temperature, turbulence) of the collapsing parent clump have not been published yet.…”

Section: Introductionmentioning

confidence: 97%

Magnetically regulated fragmentation of a massive, dense, and turbulent clump

Fontani

Commerçon

Giannetti

et al. 2016

A&A

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Massive stars, multiple stellar systems, and clusters are born of the gravitational collapse of massive, dense, gaseous clumps, and the way these systems form strongly depends on how the parent clump fragments into cores during collapse. Numerical simulations show that magnetic fields may be the key ingredient in regulating fragmentation. Here we present ALMA observations at ∼0.25 resolution of the thermal dust continuum emission at ∼278 GHz towards a turbulent, dense, and massive clump, IRAS 16061-5048c1, in a very early evolutionary stage. The ALMA image shows that the clump has fragmented into many cores along a filamentary structure. We find that the number, the total mass, and the spatial distribution of the fragments are consistent with fragmentation dominated by a strong magnetic field. Our observations support the theoretical prediction that the magnetic field plays a dominant role in the fragmentation process of massive turbulent clumps.

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Fragmentation and mass segregation in the massive dense cores of Cygnus X

Cited by 180 publications

References 72 publications

Tracing early evolutionary stages of high-mass star formation with molecular lines

Tracing early evolutionary stages of high-mass star formation with molecular lines

Fragmentation in the massive star-forming region IRAS 19410+2336

Magnetically regulated fragmentation of a massive, dense, and turbulent clump

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