The distribution of water in the high-mass star-forming region NGC 6334 I

Emprechtinger, M.; Lis, D. C.; Bell, Thomas A.; Phillips, T. G.; Schilke, P.; Comito, C.; Rolffs, R.; Tak, F. F. S. van der; Ceccarelli, C.; Aarts, H.; Bacmann, A.; Baudry, A.; Benedettini, M.; Bergin, E. A.; Blake, Geoffrey A.; Boogert, A. C. A.; Bottinelli, S.; Cabrit, S.; Caselli, P.; Castets, A.; Caux, E.; Cernicharo, J.; Codella, C.; Coutens, A.; Crimier, N.; Demyk, K.; Dominik, C.; Encrenaz, P.; Falgarone, É.; Fuente, A.; Gérin, M.; Goldsmith, P.; Helmich, Frank; Hennebelle, P.; Henning, Thomas; Herbst, Eric; Hily-Blant, Pierre; Jacq, T.; Kahane, C.; Kama, M.; Klotz, A.; Kooi, J.; Langer, W. D.; Leflóch, B.; Loose, A.; Lord, S. D.; Lorenzani, A.; Maret, S.; Melnick, Gary J.; Neufeld, David A.; Nisini, B.; Ossenkopf, V.; Pacheco, S.; Pagani, L.; Parise, B.; Pearson, J. C.; Risacher, C.; Salez, M.; Saraceno, P.; Schuster, K.; Stützki, J.; Tielens, Xander; Wiel, M. H. D. van der; Vastel, C.; Viti, S.; Wakelam, Valentine; Walters, A.; Wyrowski, F.; Yorke, H. W.

doi:10.1051/0004-6361/201015086

Cited by 33 publications

(18 citation statements)

References 23 publications

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“…With the limitations previously discussed, we find that the shock parameters of OF1 are comparable with those found for low-mass protostars with a higher pre-shock density. The derived water abundance is compatible with values of other molecular outflows (e.g., Emprechtinger et al 2010;Herczeg et al 2012). While often measurements of H 2 O abundances have large uncertainties because the H 2 column density is inferred from observations of CO or from models (for a compilation of sources, abundances and methods, see , the value inferred in our analysis is consistently derived, as the H 2 O and H 2 column densities are outcomes of the same model.…”

Section: Discussionsupporting

confidence: 80%

“…Water is a valuable tool for outflows as it is predicted to be copiously produced under the type of shock conditions expected in outflows (Flower & Pineau Des Forêts 2010). Observations of molecular outflows powered by YSOs of different masses reveal abundances of H 2 O associated with outflowing gas of the order of some 10 −5 (e.g., Emprechtinger et al 2010;Kristensen et al 2012;Nisini et al 2013). Recently, the Water In Star-forming regions with Herschel (van Dishoeck et al 2011) key program targeted several outflows from Class 0 and I low-mass YSOs in water lines.…”

Section: Introductionmentioning

confidence: 99%

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Water emission from the high-mass star-forming region IRAS 17233-3606

Leurini

Wyrowski

Codella

et al. 2014

A&A

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We investigate the physical and chemical processes at work during the formation of a massive protostar based on the observation of water in an outflow from a very young object previously detected in H 2 and SiO in the IRAS 17233-3606 region. We estimated the abundance of water to understand its chemistry, and to constrain the mass of the emitting outflow. We present new observations of shocked water obtained with the HIFI receiver onboard Herschel. We detected water at high velocities in a range similar to SiO. We self-consistently fitted these observations along with previous SiO data through a state-of-the-art, one-dimensional, stationary C-shock model. We found that a single model can explain the SiO and H 2 O emission in the red and blue wings of the spectra. Remarkably, one common area, similar to that found for H 2 emission, fits both the SiO and H 2 O emission regions. This shock model subsequently allowed us to assess the shocked water column density, N H 2 O = 1.2 × 10 18 cm −2 , mass, M H 2 O = 12.5 M ⊕ , and its maximum fractional abundance with respect to the total density, x H 2 O = 1.4 × 10 −4 . The corresponding water abundance in fractional column density units ranges between 2.5 × 10 −5 and 1.2 × 10 −5 , in agreement with recent results obtained in outflows from low-and high-mass young stellar objects.

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Section: Discussionsupporting

confidence: 80%

Section: Introductionmentioning

confidence: 99%

Water emission from the high-mass star-forming region IRAS 17233-3606

Leurini

Wyrowski

Codella

et al. 2014

A&A

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“…Finally, previous CHESS observations of NGC 6334 I have already been reported by Emprechtinger et al (2010Emprechtinger et al ( , 2013, Lis et al (2010), Ossenkopf et al (2010), van der Wiel et al (2010), and Zernickel et al (2012). The first detection of H 2 Cl + , in the ISM, toward NGC 6334 I was reported by Lis et al (2010).…”

Section: Source Backgroundsupporting

confidence: 53%

Ionization toward the high-mass star-forming region NGC 6334 I

Ortiz

Ceccarelli

Lis

et al. 2014

A&A

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Context. Ionization plays a central role in the gas-phase chemistry of molecular clouds. Since ions are coupled with magnetic fields, which can in turn counteract gravitational collapse, it is of paramount importance to measure their abundance in star-forming regions. Aims. We use spectral line observations of the high-mass star-forming region NGC 6334 I to derive the abundance of two of the most abundant molecular ions, HCO + and N 2 H + , and consequently, the cosmic ray ionization rate. In addition, the line profiles provide information about the kinematics of this region. Methods. We present high-resolution spectral line observations conducted with the HIFI instrument on board the Herschel Space Observatory of the rotational transitions with J up ≥ 5 of the molecular species C 17 O, C 18 O, HCO + , H 13 CO + , and N 2 H + . Results. The HCO + and N 2 H + line profiles display a redshifted asymmetry consistent with a region of expanding gas. We identify two emission components in the spectra, each with a different excitation, associated with the envelope of NGC 6334 I. The physical parameters obtained for the envelope are in agreement with previous models of the radial structure of NGC 6334 I based on submillimeter continuum observations. Based on our new Herschel/HIFI observations, combined with the predictions from a chemical model, we derive a cosmic ray ionization rate that is an order of magnitude higher than the canonical value of 10 −17 s −1 . Conclusions. We find evidence of an expansion of the envelope surrounding the hot core of NGC 6334 I, which is mainly driven by thermal pressure from the hot ionized gas in the region. The ionization rate seems to be dominated by cosmic rays originating from outside the source, although X-ray emission from the NGC 6334 I core could contribute to the ionization in the inner part of the envelope.

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“…Besides the diatomic hydride species HF, CH, and OH, a subset of our absorbing clouds also exhibit absorption lines due to H 2 O (Emprechtinger et al 2010 3.5 km s -1 Fig. 4.…”

Section: Relation Of Foreground Clouds To Ngc 6334mentioning

confidence: 89%

Three-dimensional distribution of hydrogen fluoride gas toward NGC 6334 I and I(N)

Wiel

Naylor

Makiwa

et al. 2016

A&A

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Context. The HF molecule has been proposed as a sensitive tracer of diffuse interstellar gas, while at higher densities its abundance could be influenced heavily by freeze-out onto dust grains. Aims. We investigate the spatial distribution of a collection of absorbing gas clouds, some associated with the dense, massive starforming core NGC 6334 I, and others with diffuse foreground clouds elsewhere along the line of sight. For the former category, we aim to study the dynamical properties of the clouds in order to assess their potential to feed the accreting protostellar cores. Methods. We use far-infrared spectral imaging from the Herschel SPIRE iFTS to construct a map of HF absorption at 243 µm in a 6 × 3 .5 region surrounding NGC 6334 I and I(N).Results. The combination of new mapping that is fully sampled spatially, but is spectrally unresolved with a previous, single-pointing, spectrally resolved HF signature yields a three-dimensional picture of absorbing gas clouds in the direction of NGC 6334. Toward core I, the HF equivalent width matches that of the spectrally resolved observation. At angular separations 20 from core I, the HF absorption becomes weaker, which is consistent with three of the seven components being associated with this dense star-forming envelope. Of the remaining four components, two disappear beyond ∼1 distance from the NGC 6334 filament, suggesting that these clouds are spatially associated with the star-forming complex. Our data also implies a lack of gas-phase HF in the envelope of core I(N). Using a simple description of adsorption onto and desorption from dust grain surfaces, we show that the overall lower temperature of the envelope of source I(N) is consistent with freeze-out of HF, while it remains in the gas phase in source I. Conclusions. We use the HF molecule as a tracer of column density in diffuse gas (n H ≈ 10 2 -10 3 cm −3 ), and find that it may uniquely trace a relatively low-density portion of the gas reservoir available for star formation that otherwise escapes detection. At higher densities prevailing in protostellar envelopes ( 10 4 cm −3 ), we find evidence of HF depletion from the gas phase under sufficiently cold conditions.

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The distribution of water in the high-mass star-forming region NGC 6334 I

Cited by 33 publications

References 23 publications

Water emission from the high-mass star-forming region IRAS 17233-3606

Water emission from the high-mass star-forming region IRAS 17233-3606

Ionization toward the high-mass star-forming region NGC 6334 I

Three-dimensional distribution of hydrogen fluoride gas toward NGC 6334 I and I(N)

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