High-angular resolution observations of methanol in the infrared dark cloud core G11.11-0.12P1

Gómez, Laura; Wyrowski, F.; Pillai, T.; Leurini, S.; Menten, K. M.

doi:10.1051/0004-6361/201016315

Cited by 22 publications

(31 citation statements)

References 41 publications

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“…1 , which is in agreement with " 10´1 0 from and on the lower end of observed values " 10´8´10´9 (Gómez et al 2011;Friberg et al 1988). Although, extraction of gas-phase abundances from observations remains challenging and needs to be approached cautiously.…”

Section: Chemical Evolutionsupporting

confidence: 69%

Methanol along the path from envelope to protoplanetary disc

Drozdovskaya¹,

Walsh²,

Visser³

et al. 2014

Monthly Notices of the Royal Astronomical Society

106

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Interstellar methanol is considered to be a parent species of larger, more complex organic molecules. A physicochemical simulation of infalling parcels of matter is performed for a low-mass star-forming system to trace the chemical evolution from cloud to disc. An axisymmetric 2D semi-analytic model generates the time-dependent density and velocity distributions, and full continuum radiative transfer is performed to calculate the dust temperature and the UV radiation field at each position as a function of time. A comprehensive gas-grain chemical network is employed to compute the chemical abundances along infall trajectories. Two physical scenarios are studied, one in which the dominant disc growth mechanism is viscous spreading, and another in which continuous infall of matter prevails. The results show that the infall path influences the abundance of methanol entering each type of disc, ranging from complete loss of methanol to an enhancement by a factor of ą 1 relative to the prestellar phase. Critical chemical processes and parameters for the methanol chemistry under different physical conditions are identified. The exact abundance and distribution of methanol is important for the budget of complex organic molecules in discs, which will be incorporated into forming planetary system objects such as protoplanets and comets. These simulations show that the comet-forming zone contains less methanol than in the precollapse phase, which is dominantly of prestellar origin, but also with additional layers built up in the envelope during infall. Such intriguing links will soon be tested by upcoming data from the Rosetta mission.

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Section: Chemical Evolutionsupporting

confidence: 69%

Methanol along the path from envelope to protoplanetary disc

Drozdovskaya¹,

Walsh²,

Visser³

et al. 2014

Monthly Notices of the Royal Astronomical Society

106

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“…An increase in the optical depth will decrease the density by roughly an order of magnitude for a given temperature and line ratio putting the range of densities for the clumps between 3 × 10 5 cm −3 to 3 × 10 6 cm −3 . These densities are consistent with earlier published results on N 2 H + in G28.34+0.06 (Chen et al 2010) and C 34 S in G11-MM (Gómez et al 2011). …”

Section: Column Density From Emission Linessupporting

confidence: 82%

The physical conditions in IRDC clumps fromHerschel/HIFI observations of H₂O

Shipman

Tak

Wyrowski

et al. 2014

A&A

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Context. The earliest phases of high-mass star formation are poorly understood. Aims. Our goal is to determine the physical conditions and kinematic structure of massive starforming cloud clumps. Methods. We analyse H 2 O 557 GHz line profiles observed with HIFI toward four positions in two infrared-dark cloud clumps. By comparison with ground-based C 17 O, N 2 H + , CH 3 OH, and NH 3 line observations, we constrain the volume density and kinetic temperature of the gas and estimate the column density and abundance of H 2 O and N 2 H + . Results. The observed water lines are complex with emission and absorption components. The absorption is redshifted and consistent with a cold envelope, while the emission is interpreted as resulting from proto-stellar outflows. The gas density in the clumps is ∼10 7 cm −3 . The o-H 2 O outflow column density is 0.3−3.0 × 10 14 cm −2 . The o-H 2 O absorption column density is between 1.5 × 10 14 and 2.6 × 10 15 cm −2 with cold o-H 2 O abundances between 1.5 × 10 −9 and 3.1 × 10 −8 . Conclusions. All clumps have high gas densities (∼10 7 cm −3 ) and display infalling gas. Three of the four clumps have outflows. The clumps form an evolutionary sequence as probed by H 2 O N 2 H + , NH 3 , and CH 3 OH. We find that G28-MM is the most evolved, followed by G11-MM and then G28-NH 3 . The least evolved clump is G11-NH 3 which shows no signposts of starformation; G11-NH 3 is a high-mass pre-stellar core.

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“…On the basis of the observed correlation between the CH 3 OH and SiO abundances, SSH10 concluded that the origin of CH 3 OH in the MSX-dark clumps is related to shocks. Gómez et al (2011) inferred CH 3 OH abundances of ∼4 × 10 −9 −3 × 10 −8 in the IRDC core G11.11-0.12 P1, and also suggested that outflow desorption is responsible for the release of CH 3 OH from ice mantles. With comparable CH 3 OH abundances, this could also be the case in the MIR-dark clump SMM 3.…”

Section: Ch 3 Ohmentioning

confidence: 99%

A molecular line study of the filamentary infrared dark cloud G304.74+01.32

Miettinen

2012

A&A

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Context. Infrared dark clouds (IRDCs) are promising sites to study the earliest formation stages of stellar clusters and high-mass stars, and the physics of molecular-cloud formation and fragmentation. Aims. We attempt to improve our understanding of the physical and chemical properties of the filamentary IRDC G304.74+01.32 (hereafter, G304.74). In particular, we investigate the kinematical and dynamical state of the cloud and clumps within it, and the amount of CO depletion. Methods. All of the submillimetre peak positions in the cloud identified from our previous LABOCA 870-μm map were observed in C 17 O(2−1) with APEX. These are the first line observations along the whole filament that have been made so far. Selected positions were also observed in the 13 CO(2−1), SiO(5−4), and CH 3 OH(5 k −4 k ) transitions at ∼1 mm. Results. The C 17 O lines were detected towards all target positions at similar radial velocities. CO does not appear to be significantly depleted in the clumps, the largest depletion factors being only about 2. Two to three methanol 5 k −4 k lines near ∼241.8 GHz were detected towards all selected positions, whereas SiO(5−4) was seen in only one of these positions, namely SMM 3. In the band covering SiO(5−4), we also detected the DCN(3−2) line towards SMM 3. The 13 CO(2−1) lines display blue asymmetric profiles, which are indicative of large-scale infall motions. The clumps show transonic to supersonic non-thermal motions, and a virial-parameter analysis suggests that most of them are gravitationally bound. The external pressure may also play a non-negligible role in the dynamics. Our analysis suggests that the fragmentation of the filament into clumps is caused by a "sausage"-type instability, in agreement with results from other IRDCs. Conclusions. The uniform C 17 O radial velocities along the G304.74 cloud shows that it is a coherent filamentary structure. Although the clumps appear to be gravitationally bound, the ambient turbulent ram pressure may be an important factor in the cloud dynamics. This is qualitatively consistent with our earlier suggestion that the filament was formed by converging supersonic turbulent flows. The poloidal magnetic field could resist the radial cloud collapse, which conforms to the low infall velocites that we derived. The cloud may be unable to form high-mass stars based on the mass-size threshold. The star-formation activity in the cloud, such as outflows, is likely responsible for the release of CO from the icy grain mantles back into the gas phase. Shocks related to outflows may also have injected CH 3 OH, SiO, and DCN into the gas-phase in SMM 3.

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High-angular resolution observations of methanol in the infrared dark cloud core G11.11-0.12P1

Cited by 22 publications

References 41 publications

Methanol along the path from envelope to protoplanetary disc

Methanol along the path from envelope to protoplanetary disc

The physical conditions in IRDC clumps fromHerschel/HIFI observations of H₂O

A molecular line study of the filamentary infrared dark cloud G304.74+01.32

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High-angular resolution observations of methanol in the infrared dark cloud core G11.11-0.12P1

Cited by 22 publications

References 41 publications

Methanol along the path from envelope to protoplanetary disc

Methanol along the path from envelope to protoplanetary disc

The physical conditions in IRDC clumps fromHerschel/HIFI observations of H2O

A molecular line study of the filamentary infrared dark cloud G304.74+01.32

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The physical conditions in IRDC clumps fromHerschel/HIFI observations of H₂O