Ammonia observations of G34.3 + 0.1: A 'bipolar' H II region?

Heaton, B. D.; Matthews, N.; Little, L. T.; Dent, W. R. F.

doi:10.1093/mnras/217.3.485

Cited by 11 publications

(15 citation statements)

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“…Comparing the distribution in SiO emission with the large scale ammonia (1, 1) and (2, 2) maps (Heaton et al 1985) and the dust continuum emission at 850 and 450 µm (Fig. 2b), which are similar and both trace the total column density, the SiO only traces the northwest extension to the molecular cloud and not the southwest, although this has similar total column density.…”

Section: The Origin Of the Ambient Velocity Siomentioning

confidence: 69%

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SiO in G34.26: Outflows and shocks in a high mass star forming region

Hatchell

Fuller²,

Millar³

2001

A&A

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Abstract.We have looked for SiO emission as evidence of shocks in the high mass star formation region G34.26+0.15. JCMT, VLA and FCRAO observations show that SiO emission is widespread across the region. The SiO emission highlights a massive, collimated outflow and other regions where stellar winds are interacting with molecular clumps. As in other star forming regions, there is also SiO at ambient velocities which is related to the outflow activity. No strong SiO abundance enhancement was measured in either the outflow or the low velocity gas, though abundances up to 10 −8 are possible if the SiO is locally enhanced in clumps and optically thick. SiO emission is not detected from the hot core itself, indicating either that SiO is not strongly enhanced in the hot core or that column densities in the region where grain mantle evaporation has taken place are low. In line of sight spiral arm clouds, we measure a SiO abundance of 0.4-2 × 10 −10 , consistent with previous estimates for quiescent clouds.

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Section: The Origin Of the Ambient Velocity Siomentioning

confidence: 69%

“…There are associated H 2 O, CH 3 OH and OH masers Hofner & Churchwell 1996;Forster & Caswell 1999). The hot core and UCHii regions are embedded in an extended molecular cloud (Matthews et al 1987;Scoville et al 1987;Carral & Welch 1992;Heaton et al 1985Heaton et al , 1993.…”

Section: Introductionmentioning

confidence: 99%

SiO in G34.26: Outflows and shocks in a high mass star forming region

Hatchell

Fuller²,

Millar³

2001

A&A

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“…The outer zone has a power-law dependence on radial distance n = n 0 r −p cm −3 , in which n 0 (the density at R max ) and p are free parameters. The range of densities explored thus encompasses the various densities inferred in previous work by van der Tak et al (2013), Garay & Rodriguez (1990), Matthews et al (1987) and Heaton et al (1985) and includes the possibilities of having a tenuous foreground cloud or a dense extended envelope or halo. Both the boundary radius and the constant density are used as free parameters.…”

Section: Density Profilementioning

confidence: 94%

“…The morphology, age and driving source of the subparsec-scale outflow components (see Sect. 1, Imai et al 2011, Klaassen & Wilson 2007 are still unknown but have suggested to be associated with individual YSO harboring a turbulent disk (Heaton et al 1985), as observed in low-mass objects. They should give rise to bipolar collimated outflows, however the reason why we are only detecting the red-shifted part must be that the opposite outflow lobe is directed tangentially to our line of sight and therefore is invisible to the telescope.…”

Section: Modeling Limitationsmentioning

confidence: 99%

On the accretion process in a high-mass star forming region

Hajigholi

Persson

Wirström

et al. 2016

A&A

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Aims. Our aim is to explore the gas dynamics and the accretion process in the early phase of high-mass star formation. Methods. The inward motion of molecular gas in the massive star forming region G34.26+0.15 is investigated by using high-resolution profiles of seven transitions of ammonia at THz frequencies observed with Herschel-HIFI. The shapes and intensities of these lines are interpreted in terms of radiative transfer models of a spherical, collapsing molecular envelope. An accelerated Lambda Iteration (ALI) method is used to compute the models. Results. The seven ammonia lines show mixed absorption and emission with inverse P-Cygni-type profiles that suggest infall onto the central source. A trend toward absorption at increasingly higher velocities for higher excitation transitions is clearly seen in the line profiles. The J = 3 ← 2 lines show only very weak emission, so these absorption profiles can be used directly to analyze the inward motion of the gas. This is the first time a multitransitional study of spectrally resolved rotational ammonia lines has been used for this purpose. Broad emission is, in addition, mixed with the absorption in the 1 0 -0 0 ortho-NH 3 line, possibly tracing a molecular outflow from the star forming region. The best-fitting ALI model reproduces the continuum fluxes and line profiles, but slightly underpredicts the emission and absorption depth in the ground-state ortho line 1 0 -0 0 . An ammonia abundance on the order of 10 −9 relative to H 2 is needed to fit the profiles. The derived ortho-to-para ratio is approximately 0.5 throughout the infalling cloud core similar to recent findings for translucent clouds in sight lines toward W31C and W49N. We find evidence of two gas components moving inwards toward the central region with constant velocities: 2.7 and 5.3 km s −1 , relative to the source systemic velocity. Attempts to model the inward motion with a single gas cloud in free-fall collapse did not succeed.

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“…The G34.26+0.15 complex contains the prototype cometary UC H ii region (component C), a HMC located in front of the cometary arc, two HC H ii regions (components A and B), and a more extended H ii region (component D) WC89;Fey et al 1994;Heaton et al 1985). Our SO observations were centered on the cometary UC H ii region, component C. Hatchell et al (2001) reported a massive blueshifted outflow seen in several SiO transitions to the northwest of the UC H ii region, which is possibly driven by component B.…”

Section: G3426+015mentioning

confidence: 99%

A Survey of the SO J _K = 1 ₀ –0 ₁ Transition toward Massive Star‐forming Regions

Mateen

Höfner

Araya

2006

ASTROPHYS J SUPPL S

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We present the most extensive survey to date of the SO ground state transition J K ¼ 1 0 Y0 1 (30 GHz). We observed 49 regions of massive star formation with the Max-Planck-Institut für Radioastronomie (MPIf R) 100 m telescope. In addition, the SO J K ¼ 4 3 Y3 2 transition was observed with the IRAM 30 m telescope toward a subsample of seven sources. Emission in the SO J K ¼ 1 0 Y0 1 transition most likely arises from the parsec-scale molecular clumps surrounding ultracompact H ii regions. In general, the SO J K ¼ 1 0 Y0 1 line has a Gaussian shape and appears to be optically thin. We derive SO column densities between 0:58 ; 10 14 and 12 ; 10 14 cm À2 and SO abundances in the range 0:18 ; 10 À9 Y4:4 ; 10 À9 . Our observations show that the SO ground state transition is an effective tool to study massive star-forming clumps, and the data presented in this paper provide a useful supplement for future multitransition SO studies.

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Ammonia observations of G34.3 + 0.1: A 'bipolar' H II region?

Cited by 11 publications

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SiO in G34.26: Outflows and shocks in a high mass star forming region

SiO in G34.26: Outflows and shocks in a high mass star forming region

On the accretion process in a high-mass star forming region

A Survey of the SO J _K = 1 ₀ –0 ₁ Transition toward Massive Star‐forming Regions

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Ammonia observations of G34.3 + 0.1: A 'bipolar' H II region?

Cited by 11 publications

References 0 publications

SiO in G34.26: Outflows and shocks in a high mass star forming region

SiO in G34.26: Outflows and shocks in a high mass star forming region

On the accretion process in a high-mass star forming region

A Survey of the SO J K = 1 0 –0 1 Transition toward Massive Star‐forming Regions

Contact Info

Product

Resources

About

A Survey of the SO J _K = 1 ₀ –0 ₁ Transition toward Massive Star‐forming Regions