A Study of the Molecular Cloud S64 with Multiple Lines of CO Isotopes

Zhu, Lei; Wu, Yuefang; Wei, Yuyang

doi:10.1088/1009-9271/6/1/007

Cited by 17 publications

(42 citation statements)

References 18 publications

(18 reference statements)

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“…3, similar to what was found (320 M ) from the 13 CO(2-1) map by Zhu et al (2006). The mean column density over this region is N H 2 ∼ 1.8 × 10 22 cm −2 .…”

Section: The W40 Hii Regionsupporting

confidence: 88%

“…3. It mainly features a ring-like structure following the outer border of the W40 HII region (Smith et al 1985;Vallee 1987;Kuhn et al 2010), and spatially coincident with the CO emission mapped by Zhu et al (2006). In addition to this western dense shell, the map shows elongated structures (also containing compact sources) in the eastern part of the photo-dissociated region, while the central part of the infrared cluster containing most of the pre-main sequence objects (Kuhn et al 2010) does not show any evidence for cold dust emission at 1.2 mm.…”

Section: Main Features Of the Millimeter Continuum Mapsmentioning

confidence: 60%

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The formation of active protoclusters in the Aquila rift: a millimeter continuum view

Maury¹,

André²,

Men’shchikov³

et al. 2011

A&A

125

244

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While most stars are believed to form in stellar clusters, the formation and early evolution of young stellar clusters is still largely unknown. Improving our knowledge of the earliest phases of clustered star formation is crucial for understanding the origin of the stellar initial mass function and the efficiency of the star formation process, which both play a key role in the evolution of galaxies. Here, we present an analysis of the Aquila rift complex which addresses the questions of the star formation rate (SFR), star formation efficiency (SFE) and typical lifetime of the Class 0 protostellar phase in two nearby cluster-forming clumps: the Serpens South and W40 protoclusters. We carried out a 1.2 mm dust continuum mapping of the Aquila rift complex with the MAMBO bolometer array on the IRAM 30 m telescope. Using a multi-scale source extraction method, we perform a systematic source extraction in our millimeter continuum map. Based on complementary data from the Herschel Gould Belt survey and Spitzer maps, we characterize the spectral energy distributions (SEDs) of the 77 mm continuum sources detected with MAMBO and estimate their evolutionary stages. Taking advantage of the comprehensive dataset available for the Serpens South region, spanning wavelengths from 2 μm to 1.2 mm, we estimate the numbers of young stellar objects (YSOs) at different evolutionary stages and find a ratio of Class 0 to Class I protostars N(0)/N(I) = 0.19−0.27. This low ratio supports a scenario of relatively fast accretion at the beginning of the protostellar phase, and leads to a Class 0 lifetime of ∼4−9 × 10 4 yr. We also show that both the Serpens South and W40 protoclusters are characterized by large fractions of protostars and high SFRs ∼ 20−50 M Myr −1 pc −2 , in agreement with the idea that these two nearby clumps are active sites of clustered star formation currently undergoing bursts of star formation, and have the potential ability to form bound star clusters. While the formation of these two protoclusters is likely to have been initiated in a very different manner, the resulting protostellar populations are observed to be very similar. This suggests that after the onset of gravitational collapse, the detailed manner in which the collapse has been initiated does not affect much the ability of a clump to form stars.

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“…3, similar to what was found (320 M ) from the 13 CO(2-1) map by Zhu et al (2006). The mean column density over this region is N H 2 ∼ 1.8 × 10 22 cm −2 .…”

Section: The W40 Hii Regionsupporting

confidence: 88%

Section: Main Features Of the Millimeter Continuum Mapsmentioning

confidence: 60%

The formation of active protoclusters in the Aquila rift: a millimeter continuum view

Maury¹,

André²,

Men’shchikov³

et al. 2011

A&A

125

244

View full text Add to dashboard Cite

show abstract

“…The CS emission is strong towards the eastern branch of the ring while NH 3 , N 2 H + and H 13 CO + are strong towards the western branch. The HCN, HCO + and CO [4] emission is detected over extended part of the region and show practically no correlation with the dust.…”

Section: Molecular Line Data Modeling Resultsmentioning

confidence: 91%

Induced star formation in the W40 region

Pirogov¹

2016

Proceedings of Frontier Research in Astrophysics — PoS(FRAPWS2014)

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A dense core associated with the W40 H II region has been observed in molecular lines and in continuum. The core consists of a clumpy dust ring and an extended molecular emission region. There are sharp differences in morphologies of dust and molecular gas. The ring is probably formed by the "collect & collapse" process due to an expansion of neighbouring compact H II region into surrounding medium of fairly uniform and high density (∼ 10 5 cm −3 ). There is a strong chemical differentiation in the ring. The NH 3 , N 2 H + and H 13 CO + abundances are enhanced in the western clumps while the CS abundance is enhanced in the east. The eastern clumps which are closer to the main H II region are more massive and turbulent, show indications of infall and probably are more evolved than the western ones. An interaction between ionized gas and neutral material which is taking place in their vicinity triggers a new phase of star formation.

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“…It cannot be ruled out that this ratio could vary in the dense gas near an HII zone. For example, the HCN, HCO + , CS and 13 CO molecular emission is detected inside the region bounded by the ring, where the dust emission is considerably reduced [11,12,23]. It is shown in [27] that spatial fluctuations of the dust density in turbulent clouds can occur independently of gas-density fluctuations on scales compared with the sizes of protostellar cores.…”

Section: Discussionmentioning

confidence: 99%

“…The western clumps 6-9 are associated with the N 2 H + and NH emission is apparently associated with regions of high density and not with enhanced column density of the gas. The spatial distributions of the different CO isotopic line intensities [23] correlate weakly with the ring structure, and may be tracers of a more diffuse envelope around the ring. The clumpy ring probably formed due to the expansion of the HII zone associated with IRS 5 into the parent dense cloud.…”

Section: Comparison Of the Model And The Observed Clump Parametersmentioning

confidence: 99%

The region of triggered star formation W40: Observations and model

Pirogov

2015

Astron. Rep.

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A "collect and collapse" model of triggered star formation is used to estimate the parameters of ring-like structure consisted of a sequence of low-mass clumps in the W40 region. The model parameters are close to the observed ones if the density of the cloud in which the HII zone is expanding is fairly high ( > ∼ 10 5 cm −3 ) and the luminosity of the driving source exceeds previous estimate. Probable reasons for the scatter of the observed parameters of the clumps are discussed.

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A Study of the Molecular Cloud S64 with Multiple Lines of CO Isotopes

Cited by 17 publications

References 18 publications

The formation of active protoclusters in the Aquila rift: a millimeter continuum view

The formation of active protoclusters in the Aquila rift: a millimeter continuum view

Induced star formation in the W40 region

The region of triggered star formation W40: Observations and model

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