MERLIN and VLA observations of the star-forming region G35.2-0.7N

Brebner, G. C.; Heaton, B. D.; Cohen, R. J.; Davies, S. R.

doi:10.1093/mnras/229.4.679

Cited by 19 publications

(32 citation statements)

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“…Support for this interpretation comes from the ammonia (2, 2) observations of Little et al (1985), which peak toward G35.2N. However, the ammonia (3, 3) observations of Brebner et al (1987) clearly show the emission peaks at the position of G35MM2. Therefore, at the moment, it is not possible to distinguish one hypothesis unambiguously from the other and we propose further observations should be made using higherexcitation transitions.…”

Section: Discussionmentioning

confidence: 89%

Molecular outflows from G35.2-0.74N

Birks¹,

Fuller²,

Gibb

2006

A&A

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We present interferometric observations of the massive star-forming region associated with G35.2-0.74N using the Berkeley Illinois Maryland Association Array. With the aim of better understanding the outflow in this region we observed 12 CO J = 1 → 0, C 17 O J = 1 → 0 and the 2.7 mm continuum. The C 17 O and continuum emission peak close to the sources G35.2-0.74N (G35.2N) and G35MM2 and indicate a mass of ∼40−140 M of circumstellar material associated with these sources. The 12 CO traces a weak filament of emission coincident with the radio and infrared jet from G35.2N but the emission is dominated by an extended outflow with a NE-SW axis which has a total mass of ∼13 M . Each lobe of this extended outflow has a hollow shell structure and the location of these shells makes the source G35MM2 a more likely candidate for the source driving the outflow than G35.2N. The mass-velocity distribution is calculated for several parts of the outflow. Fitting these distributions with power laws some of the same break-points are seen as previously identified in the 12 CO J = 3 → 2 emission from the outflow. We conclude this indicates the temperature dependence of emissivity is not responsible for all the break-points seen and molecular dissociation is a more plausible explanation for their origin. We model the molecular outflow using the ZEUS-2D hydrodynamic code which we have augmented so that it can also track the composition of the gas. We find that a general hydromagnetic wind, without an enchanced, on axis, jet-like component, can reproduce the shape of the observed outflow. Models looking at the time evolution of the stellar wind indicate that the structure of the outflow is dominated by the initial wind conditions, rather than its later evolution. The models also show that scaling the density of the wind profile effects the apparent collimation of the resulting outflow. This may help explain some of the apparent differences between outflows from high mass and low mass young stars.

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Section: Discussionmentioning

confidence: 89%

Molecular outflows from G35.2-0.74N

Birks¹,

Fuller²,

Gibb

2006

A&A

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“…The strongest of these, cores A and B, are located at the center of the elongated structure, and were already identified by Sánchez-Monge et al (2013b). These two cores are associated with faint centimeter continuum emission likely tracing young H ii regions or radiojets (see Gibb et al 2003;Sánchez-Monge et al 2013b), with a number of 1665-MHz OH maser features (Brebner et al 1987;Hutawarakorn & Cohen 1999), and with probably 3 6.7 GHz CH 3 OH maser emission. Core C, located ∼3 to the SE of core B, coincides with the millimeter source G35MM2 reported by Gibb et al (2003).…”

Section: Continuum Emissionmentioning

confidence: 87%

“…There are some morphological differences to the southeast of the elongated 3 The 6.7 GHz CH 3 OH maser observations carried out with the Japanese VLBI Network (JVN; Sugiyama et al 2008) and the European VLBI Neatwork (EVN; Surcis et al 2012) were performed without phase-referencing and it is thus impossible to establish the absolute position of the masers. However, the CH 3 OH maser distribution seems to match the OH maser distribution (Brebner et al 1987;Hutawarakorn & Cohen 1999); since the latter are associated with cores A and B, it seems likely that the methanol masers are also associated with these two cores. The frequency is that of the K = 0 component.…”

Section: Continuum Emissionmentioning

confidence: 88%

“…The dashed curve outlines the shape of the jet, which is bending by almost ∼90 • at an offset of ∼11 to the north of core B. structure has been indeed proposed by several authors. In particular, Little et al (1985) and Brebner et al (1987) revealed a large (∼1 or 0.6 pc) elongated structure in NH 3 and CS, oriented SE-NW, i.e., perpendicular to the large-scale outflow, and with a velocity gradient, which they interpret as a large rotating disk/toroid. More recently, Gibb et al (2003) studied the G35.20N star forming complex with the BIMA interferometer in the H 13 CO + (1-0) and H 13 CN (1-0) transitions, with an angular resolution of ∼10 .…”

Section: Nature Of the Elongated Structurementioning

confidence: 98%

“…Emission from dense gas tracers (e.g., NH 3 , C 18 O, CS, HCN, H 13 CO + ), as well as continuum dust emission at millimeter wavelengths (e.g., Little et al 1985;Brebner et al 1987;Gibb et al 2003;López-Sepulcre et al 2009), have revealed the presence of a dense clump elongated perpendicular to the NE-SW outflow, with a velocity gradient from NW (∼32 km s −1 ) to SE (∼36 km s −1 ). This velocity gradient was first thought to originate from a large (∼0.6 pc) flattened structure rotating about the axis of the NE-SW outflow.…”

Section: Introductionmentioning

confidence: 99%

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A necklace of dense cores in the high-mass star forming region G35.20−0.74 N: ALMA observations

Sánchez-Monge

Beltrán

Cesaroni

et al. 2014

A&A

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Context. The formation process of high-mass stars (with masses >8 M ) is still poorly understood, and represents a challenge from both the theoretical and observational points of view. The advent of the Atacama Large Millimeter Array (ALMA) is expected to provide observational evidence to better constrain the theoretical scenarios. Aims. The present study aims at characterizing the high-mass star forming region G35.20−0.74 N, which is found associated with at least one massive outflow and contains multiple dense cores, one of them recently found associated with a Keplerian rotating disk. Methods. We used the radio-interferometer ALMA to observe the G35.20−0.74 N region in the submillimeter continuum and line emission at 350 GHz. The observed frequency range covers tracers of dense gas (e.g., H 13 CO + , C 17 O), molecular outflows (e.g., SiO), and hot cores (e.g., CH 3 CN, CH 3 OH). These observations were complemented with infrared and centimeter data. Results. The ALMA 870 μm continuum emission map reveals an elongated dust structure (∼0.15 pc long and ∼0.013 pc wide; full width at half maximum) perpendicular to the large-scale molecular outflow detected in the region, and fragmented into a number of cores with masses ∼1-10 M and sizes ∼1600 AU (spatial resolution ∼960 AU). The cores appear regularly spaced with a separation of ∼0.023 pc. The emission of dense gas tracers such as H 13 CO + or C 17 O is extended and coincident with the dust elongated structure. The three strongest dust cores show emission of complex organic molecules characteristic of hot cores, with temperatures around 200 K, and relative abundances 0.2-2 × 10 −8 for CH 3 CN and 0.6-5 × 10 −6 for CH 3 OH. The two cores with highest mass (cores A and B) show coherent velocity fields, with gradients almost aligned with the dust elongated structure. Those velocity gradients are consistent with Keplerian disks rotating about central masses of 4-18 M . Perpendicular to the velocity gradients we have identified a large-scale precessing jet/outflow associated with core B, and hints of an east-west jet/outflow associated with core A. Conclusions. The elongated dust structure in G35.20−0.74 N is fragmented into a number of dense cores that may form high-mass stars. Based on the velocity field of the dense gas, the orientation of the magnetic field, and the regularly spaced fragmentation, we interpret this elongated structure as the densest part of a 1D filament fragmenting and forming high-mass stars.

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The relationship between masers and massive star formation: what can be learned from the infrared?

Buizer

2002

Symp. - Int. Astron. Union

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The infrared represents an alternative wavelength regime in which to study the environments of maser emission, while at the same time complementing the information obtained through radio techniques. The near infrared (1-2 µm) yields information on outflows, shocks, and reflected dust emission, while the thermal infrared (3-30 µm) yields information on the thermal dust distribution around stars. Thus, the infrared regime yields important clues in determining whether masers exist in shocks, outflows, circumstellar accretion disks, or in the dense medium close to protostars.

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MERLIN and VLA observations of the star-forming region G35.2-0.7N

Cited by 19 publications

References 0 publications

Molecular outflows from G35.2-0.74N

Molecular outflows from G35.2-0.74N

A necklace of dense cores in the high-mass star forming region G35.20−0.74 N: ALMA observations

The relationship between masers and massive star formation: what can be learned from the infrared?

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