2016A&A...593A..37V


Query : 2016A&A...593A..37V

2016A&A...593A..37V - Astronomy and Astrophysics, volume 593A, 37-37 (2016/9-1)

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

VAN DER WIEL M.H.D., NAYLOR D.A., MAKIWA G., SATTA M. and ABERGEL A.

Abstract (from CDS):

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 star-forming 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 243µm in a 6'x3.5' 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 (nH~=102-103cm–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 (≥104cm–3), we find evidence of HF depletion from the gas phase under sufficiently cold conditions.

Abstract Copyright: © ESO 2016

Journal keyword(s): ISM: molecules - ISM: clouds - ISM: individual objects: NGC 6334 - stars: formation - circumstellar matter - astrochemistry

VizieR on-line data: <Available at CDS (J/A+A/593/A37): list.dat spire_hf.fit>

Simbad objects: 12

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Number of rows : 12
N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2023
#notes
1 NAME OMC-1 MoC 05 35 14 -05 22.4           ~ 1127 2
2 NAME Orion Bright Bar reg 05 35 22.30 -05 24 33.0           ~ 821 0
3 V* V2457 Ori Or* 05 35 26.97000 -05 09 54.4644         18.858 ~ 143 0
4 OMC 2 MoC 05 35 27 -05 10.1           ~ 434 1
5 Mrk 231 Sy1 12 56 14.2341182928 +56 52 25.238373852   14.68 13.84     ~ 1930 3
6 QSO J1415+1129 QSO 14 15 46.25 +11 29 43.4   17.63 17.23     ~ 627 0
7 NGC 6334 HII 17 20 53 -36 07.9           ~ 654 0
8 NAME NGC 6334 I(N) smm 17 20 54 -35 45.0           ~ 141 1
9 NAME Galactic Center reg 17 45 39.60213 -29 00 22.0000           ~ 13437 0
10 NAME Sgr B2 MoC 17 47 20.4 -28 23 07           ~ 2148 1
11 NAME Sgr B2 Main Rad 17 47 20.5 -28 23 06           ~ 380 1
12 NAME Sgr Arm PoG 19 00 -30.0           ~ 609 1

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2023.02.01-08:04:12

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