ATCA 3 mm observations of NGC 6334I and I(N): dense cores, outflows, and an UCH II region

Beuther, H.; Walsh, A. J.; Thorwirth, Sven; Zhang, Qizhou; Hunter, T. R.; Megeath, S. Thomas; Menten, K. M.

doi:10.1051/0004-6361:20079014

Cited by 31 publications

(35 citation statements)

References 51 publications

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“…The SMA resolves the core into several mm peaks (Hunter et al 2006), which show very different emission-line characteristics (Brogan et al 2009). The large-scale environment was mapped by Walsh et al (2010), and an outflow is also present (Beuther et al 2008). This source was observed with Herschel/HIFI (Emprechtinger et al 2010;Ceccarelli et al 2010).…”

Section: Ngc 6334-imentioning

confidence: 83%

Structure of evolved cluster-forming regions

Rolffs

Schilke

Wyrowski

et al. 2011

A&A

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Context. An approach towards understanding the formation of massive stars and star clusters is to study the structure of their hot core phase, an evolutionary stage where dust has been heated, but molecules have not yet been destroyed by ultraviolet radiation. These hot molecular cores are very line-rich, but the interpretation of line surveys is also hampered by poor knowledge of the physical and chemical structure. Aims. To constrain the radial structure of high-mass star-forming regions containing hot cores, we attempt to reproduce by radiative transfer modeling both the intensity and shape of a variety of molecular lines. Methods. We observed 12 hot cores with the Atacama Pathfinder EXperiment (APEX) in lines of HCN, HCO + , CO, and their isotopologues, including high-J lines and vibrationally excited HCN. We investigate how well the sources can be modeled as centrally heated spheres with a power-law density gradient, making use of the radiative transfer code RATRAN and the radial profile of the submm continuum emission, taken from the APEX Telescope Large Area Survey of the GALaxy (ATLASGAL). Results. Most of the observed lines have complicated shapes that incorporate self-absorption, asymmetries, and line wings. Vibrationally excited HCN is detected in all sources, and vibrationally excited H 13 CN in half of the sources. We are able to successfully model most features seen in the APEX data, such as the ratio of the isotopologue lines (very high optical depths), self-absorption (temperature gradient), blue asymmetries (moderate infall), vibrationally excited HCN (high inner temperatures), and H 13 CN (high HCN abundance under dense and hot conditions). Other features could not be reproduced, such as an occasional lack of self-absorption, the emission from high-J lines in the outer pixels of the CHAMP+ receiver (15 −20 from the center), the outflow wings, and the red asymmetric profiles. Conclusions. The amount of molecular gas, in particular of HCN, at very high temperatures is larger than previously thought. A complex interplay between infall and outflow motions is present. Our basic model assumptions of pure central heating and a power-law radial density distribution can serve as approximations for most sources, but are too simple to explain all observed lines. In particular, taking into account clumpiness, multiplicity of heating sources and a more complex velocity field seems to be necessary to more closely match model calculations to observations. This would require three-dimensional radiative transfer modeling of high-resolution interferometric data.

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Section: Ngc 6334-imentioning

confidence: 83%

Structure of evolved cluster-forming regions

Rolffs

Schilke

Wyrowski

et al. 2011

A&A

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“…Muños et al 2007, and references therein). The massive twin cores NGC 6334I and I(N) have been studied for more than two decades and are believed to be at different evolutionary stages (see Beuther et al 2008, and references therein). These cores are well known to host unusual methanol masers of both classes (e.g.…”

Section: Resultsmentioning

confidence: 99%

New 9.9-GHz methanol masers

Voronkov¹,

Caswell²,

Ellingsen³

et al. 2010

Monthly Notices of the Royal Astronomical Society

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The Australia Telescope Compact Array (ATCA) has been used to make the first extensive search for the class I methanol masers at 9.9 GHz. In total, 48 regions of high-mass star formation were observed. In addition to masers in W33-Met (G12.80-0.19) and G343.12-0.06 (IRAS 16547-4247) which have already been reported in the literature, two new 9.9-GHz masers have been found towards G331.13-0.24 and G19.61-0.23. We have determined absolute positions (accurate to roughly a second of arc) for all the detected masers and suggest that some class I masers may be associated with shocks driven into molecular clouds by expanding HII regions. Our observations also imply that the evolutionary stage of a high-mass star forming region when the class I masers are present can outlast the stage when the class II masers at 6.7 GHz are detectable, and overlaps significantly with the stage when OH masers are active.Comment: accepted for publication in MNRAS, 14 pages, 3 figures, 4 table

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“…Continuum emission from our sources is determined with well-sampled observations from various telescopes including IRAS (archive 3 ), Spitzer (archive 4 ), MSX (archive 5 ), JCMT (archive 6 , and Vallée & Fiege 2006;Sandell 2000;McCutcheon et al 2000), KAO (Harvey et al 1986;Lester et al 1985), CSO (Motte et al 2003), SMA Hunter et al 2006), APEX, SEST Muñoz et al 2007), IRAM-30m (Beuther et al 2002b;Motte et al 2007), IRAM-PdB ), VLA (Beuther et al 2002a;Rodríguez et al 2007), ATCA (Walsh et al 1998;Beuther et al 2008), OVRO (Woody et al 1989), and Herschel-HIFI/PACS (van der Tak et al 2013). In particular, flux densities below 35 μm come from Spitzer and MSX observations.…”

Section: Source Samplementioning

confidence: 99%

Herschel-HIFI view of mid-IR quiet massive protostellar objects

Herpin

Chavarría

Jacq

et al. 2016

A&A

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Aims. We present Herschel/HIFI observations of 14 water lines in a small sample of Galactic massive protostellar objects: NGC 6334I(N), DR21(OH), IRAS 16272-4837, and IRAS 05358+3543. Using water as a tracer of the structure and kinematics, we individually study each of these objects with the aim to estimate the amount of water around them, but to also to shed light on the high-mass star formation process. Methods. We analyzed the gas dynamics from the line profiles using Herschel-HIFI observations acquired as part of the WISH keyproject of 14 far-IR water lines (H 2 O) and several other species. Then through modeling the observations using the RATRAN radiative transfer code, we estimated outflow, infall, turbulent velocities, and molecular abundances and investigated the correlation with the evolutionary status of each source. Results. The four sources (and the previously studied W43-MM1) have been ordered in terms of evolution based on their spectral energy distribution from youngest to older: 1) NGC 64334I(N); 2) W43-MM1; 3) DR21(OH); 4) IRAS 16272-4837; 5) IRAS 05358+3543. The molecular line profiles exhibit a broad component coming from the shocks along the cavity walls that is associated with the protostars, and an infalling (or expanding, for IRAS 05358+3543) and passively heated envelope component, with highly supersonic turbulence that probably increases with the distance from the center. Accretion rates between 6.3 × 10 −5 and 5.6 × 10 −4 M yr −1 are derived from the infall observed in three of our sources. The outer water abundance is estimated to be at the typical value of a few 10 −8 , while the inner abundance varies from 1.7 × 10 −6 to 1.4 × 10 −4 with respect to H 2 depending on the source. Conclusions. We confirm that regions of massive star formation are highly turbulent and that the turbulence probably increases in the envelope with the distance to the star. The inner abundances are lower than the expected, 10 −4 , perhaps because our observed lines do not probe deep enough into the inner envelope or because photodissociation through protostellar UV photons is more efficient than expected. We show that the higher the infall or expansion velocity in the protostellar envelope, the higher the inner abundance. This may indicate that higher infall or expansion velocities generate shocks that will sputter water from the ice mantles of dust grains in the inner region. High-velocity water must be formed in the gas phase from shocked material.

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ATCA 3 mm observations of NGC 6334I and I(N): dense cores, outflows, and an UCH II region

Cited by 31 publications

References 51 publications

Structure of evolved cluster-forming regions

Structure of evolved cluster-forming regions

New 9.9-GHz methanol masers

Herschel-HIFI view of mid-IR quiet massive protostellar objects

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