Widespread SiO and CH3OH Emission in Filamentary Infrared-Dark Clouds★

Cosentino, Giuliana; Jiménez-Serra, I.; Henshaw, Jonathan D.; Caselli, P.; Viti, S.; Barnes, Ashley; Fontani, F.; Tan, J.; Pon, Andy

doi:10.1093/mnras/stx3013

Cited by 27 publications

(45 citation statements)

References 71 publications

(130 reference statements)

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“…We find that around 5 to 15 cores are present within each cloud, with the exception of Cloud G where no cores have been identified. This was likely because the mapped region of Cloud G is, by design, focused on the eastern shocked region explored by Cosentino et al (2018Cosentino et al ( , 2019, and not the main dust extinction/continuum feature(s) previously identified within this cloud (e.g. Rathborne et al 2006;Butler & Tan 2012;Kainulainen & Tan 2013).…”

Section: Core Identificationmentioning

confidence: 99%

ALMA–IRDC: dense gas mass distribution from cloud to core scales

Barnes

Henshaw

Fontani

et al. 2021

Monthly Notices of the Royal Astronomical Society

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Infrared dark clouds (IRDCs) are potential hosts of the elusive early phases of high-mass star formation (HMSF). Here we conduct an in-depth analysis of the fragmentation properties of a sample of 10 IRDCs, which have been highlighted as some of the best candidates to study HMSF within the Milky Way. To do so, we have obtained a set of large mosaics covering these IRDCs with ALMA at band 3 (or 3 mm). These observations have a high angular resolution (∼ 3″; ∼ 0.05 pc), and high continuum and spectral line sensitivity (∼ 0.15 mJy beam−1 and ∼ 0.2 K per 0.1 km s−1 channel at the N2H+ (1 − 0) transition). From the dust continuum emission, we identify 96 cores ranging from low- to high-mass (M = 3.4 − 50.9M⊙) that are gravitationally bound (αvir = 0.3 − 1.3) and which would require magnetic field strengths of B = 0.3 − 1.0 mG to be in virial equilibrium. We combine these results with a homogenised catalogue of literature cores to recover the hierarchical structure within these clouds over four orders of magnitude in spatial scale (0.01 pc – 10 pc). Using supplementary observations at an even higher angular resolution, we find that the smallest fragments (< 0.02 pc) within this hierarchy do not currently have the mass and/or the density required to form high-mass stars. Nonetheless, the new ALMA observations presented in this paper have facilitated the identification of 19 (6 quiescent and 13 star-forming) cores that retain >16 M⊙ without further fragmentation. These high-mass cores contain trans-sonic non-thermal motions, are kinematically sub-virial, and require moderate magnetic field strengths for support against collapse. The identification of these potential sites of high-mass star formation represents a key step in allowing us to test the predictions from high-mass star and cluster formation theories.

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Section: Core Identificationmentioning

confidence: 99%

ALMA–IRDC: dense gas mass distribution from cloud to core scales

Barnes

Henshaw

Fontani

et al. 2021

Monthly Notices of the Royal Astronomical Society

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“…Besides the broad components, SiO lines also show a narrow component. Narrow SiO (2-1) emission has been detected in infrared dark clouds (Jiménez-Serra et al 2010;Csengeri et al 2016b;Cosentino et al 2018Cosentino et al , 2020 and high-mass proto-cluster forming regions (Nguyen-Lu'o'ng et al 2013;Louvet et al 2016;Csengeri et al 2016b;Liu et al 2020a). Such narrow gaussian component may come from the thermal radiation of cores in molecular cloud, or reproduced by low-velocity shocks (Louvet et al 2016).…”

Section: Molecular Outflows and Shocked Gasmentioning

confidence: 99%

ATOMS: ALMA Three-millimeter Observations of Massive Star-forming regions–VI. On the formation of the ‘L’ type filament in G286.21+0.17

Zhou

Liu

et al. 2021

Monthly Notices of the Royal Astronomical Society

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Filaments play an important role in star formation, but the formation process of filaments themselves is still unclear. The high-mass star forming clump G286.21+0.17 (G286 for short) that contains an “L” type filament was thought to undergo global collapse. Our high resolution ALMA band 3 observations resolve the gas kinematics of G286 and reveal two sub-clumps with very different velocities inside it. We find that the “blue profile” (an indicator of gas infall) of HCO+ lines in single dish observations of G286 is actually caused by gas emission from the two sub-clumps rather than gas infall. We advise great caution in interpreting gas kinematics (e.g. infall) from line profiles toward distant massive clumps in single dish observations. Energetic outflows are identified in G286 but the outflows are not strong enough to drive expansion of the two sub-clumps. The two parts of the “L” type filament (“NW-SE” and “NE-SW” filaments) show prominent velocity gradients perpendicular to their major axes, indicating that they are likely formed due to large-scale compression flows. We argue that the large-scale compression flows could be induced by the expansion of nearby giant H ii regions. The “NW-SE” and “NE-SW” filaments seem to be in collision, and a large amount of gas has been accumulated in the junction region where the most massive core G286c1 forms.

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“…Figure 3 shows the integrated intensity maps of CO (J=2-1), SiO (J=5-4), CH 3 OH (J K = 4 2 -3 1 ), H 2 CO (J Ka,Kc = 3 0,3 -2 0,2 ), H 2 CO (J Ka,Kc = 3 2,1 -2 2,0 ), H 2 CO (J Ka,Kc = 3 2,2 -2 2,1 ), and HC 3 N (J=24-23) which are often used as molecular outflow tracers (e.g., Tafalla et al 2010;Sanhueza et al 2010;Zhang et al 2015;Cosentino et al 2018;Tychoniec et al 2019; 2019, 2020). For each line, we integrated the emission greater than 4σ in the following velocity ranges, where σ is the rms noise level in the line-free channels (Table 2).…”

Section: Molecular Line Emissionmentioning

confidence: 99%

The ALMA Survey of 70 $μ$m Dark High-mass Clumps in Early Stages (ASHES). IV. Star formation signatures in G023.477

Morii,

Sanhueza,

Nakamura

et al. 2021

Preprint

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With a mass of ∼1000 M and a surface density of ∼0.5 g cm −2 , G023.477+0.114 also known as IRDC 18310-4 is an infrared dark cloud (IRDC) that has the potential to form high-mass stars and has been recognized as a promising prestellar clump candidate. To characterize the early stages of high-mass star formation, we have observed G023.477+0.114 as part of the ALMA Survey of 70 µm Dark Highmass Clumps in Early Stages (ASHES). We have conducted ∼1. 2 resolution observations with the Atacama Large Millimeter/submillimeter Array (ALMA) at 1.3 mm in dust continuum and molecular line emission. We identified 11 cores, whose masses range from 1.1 M to 19.0 M . Ignoring magnetic fields, the virial parameters of the cores are below unity, implying that the cores are gravitationally bound. However, when magnetic fields are included, the prestellar cores are close to virial equilibrium, while the protostellar cores remain sub-virialized. Star formation activity has already started in this clump. Four collimated outflows are detected in CO and SiO. H 2 CO and CH 3 OH emission coincide with the high-velocity components seen in the CO and SiO emission. The outflows are randomly oriented for the natal filament and the magnetic field. The position-velocity diagrams suggest that episodic mass ejection has already begun even in this very early phase of protostellar formation. The masses of the identified cores are comparable to the expected maximum stellar mass that this IRDC could form (8-19 M ). We explore two possibilities on how IRDC G023.477+0.114 could eventually form high-mass stars in the context of theoretical scenarios.

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Widespread SiO and CH3OH Emission in Filamentary Infrared-Dark Clouds★

Cited by 27 publications

References 71 publications

ALMA–IRDC: dense gas mass distribution from cloud to core scales

ALMA–IRDC: dense gas mass distribution from cloud to core scales

ATOMS: ALMA Three-millimeter Observations of Massive Star-forming regions–VI. On the formation of the ‘L’ type filament in G286.21+0.17

The ALMA Survey of 70 $μ$m Dark High-mass Clumps in Early Stages (ASHES). IV. Star formation signatures in G023.477

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