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Radiative and mechanical feedback into the molecular gas in the Large Magellanic Cloud: I. N159W

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We present <i>Herschel <i/>SPIRE Fourier Transform Spectrometer (FTS) observations of N159W, an active star-forming region in the Large Magellanic Cloud (LMC). In our observations, a number of far-infrared cooling lines, including carbon monoxide (CO) <i>J<i/> = 4 → 3 to <...

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Main Authors: Lee, Min-Young (Author) , Madden, S. C. (Author) , Lebouteiller, V. (Author) , Gusdorf, A. (Author) , Godard, B. (Author) , Wu, R. (Author) , Galametz, M. (Author) , Cormier, Diane (Author) , Petit, F. Le (Author) , Roueff, E. (Author) , Bron, E. (Author) , Carlson, L. (Author) , Chevance, M. (Author) , Fukui, Y. (Author) , Galliano, F. (Author) , Hony, S. (Author) , Hughes, A. (Author) , Indebetouw, R. (Author) , Israel, F. P. (Author) , Kawamura, A. (Author) , Bourlot, J. Le (Author) , Lesaffre, P. (Author) , Meixner, M. (Author) , Muller, E. (Author) , Nayak, O. (Author) , Onishi, T. (Author) , Roman-Duval, J. (Author) , Sewiło, M. (Author)
Format: Article (Journal)
Language:English
Published: 06 December 2016
In: Astronomy and astrophysics
Year: 2016, Volume: 596, Pages: 1-25
ISSN:1432-0746
DOI:10.1051/0004-6361/201628098
Online Access:Verlag, lizenzpflichtig, Volltext: https://doi.org/10.1051/0004-6361/201628098
Verlag, lizenzpflichtig, Volltext: https://www.aanda.org/articles/aa/abs/2016/12/aa28098-16/aa28098-16.html
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Author Notes:M.-Y. Lee, S. C. Madden, V. Lebouteiller, A. Gusdorf, B. Godard, R. Wu, M. Galametz, D. Cormier, F. Le Petit, E. Roueff, E. Bron, L. Carlson, M. Chevance, Y. Fukui, F. Galliano, S. Hony, A. Hughes, R. Indebetouw, F. P. Israel, A. Kawamura, J. Le Bourlot, P. Lesaffre, M. Meixner, E. Muller, O. Nayak, T. Onishi, J. Roman-Duval, and M. Sewiło
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Summary:We present <i>Herschel <i/>SPIRE Fourier Transform Spectrometer (FTS) observations of N159W, an active star-forming region in the Large Magellanic Cloud (LMC). In our observations, a number of far-infrared cooling lines, including carbon monoxide (CO) <i>J<i/> = 4 → 3 to <i>J<i/> = 12 → 11, [CI] 609 <i>μ<i/>m and 370 <i>μ<i/>m, and [NII] 205 <i>μ<i/>m, are clearly detected. With an aim of investigating the physical conditions and excitation processes of molecular gas, we first construct CO spectral line energy distributions (SLEDs) on ~10 pc scales by combining the FTS CO transitions with ground-based low-<i>J<i/> CO data and analyze the observed CO SLEDs using non-LTE (local thermodynamic equilibrium) radiative transfer models. We find that the CO-traced molecular gas in N159W is warm (kinetic temperature of 153-754 K) and moderately dense (H<sub>2<sub/> number density of (1.1−4.5) × 10<sup>3<sup/> cm<sup>-3<sup/>). To assess the impact of the energetic processes in the interstellar medium on the physical conditions of the CO-emitting gas, we then compare the observed CO line intensities with the models of photodissociation regions (PDRs) and shocks. We first constrain the properties of PDRs by modeling <i>Herschel <i/>observations of [OI] 145 <i>μ<i/>m, [CII] 158 <i>μ<i/>m, and [CI] 370 <i>μ<i/>m fine-structure lines and find that the constrained PDR components emit very weak CO emission. X-rays and cosmic-rays are also found to provide a negligible contribution to theCO emission, essentially ruling out ionizing sources (ultraviolet photons, X-rays, and cosmic-rays) as the dominant heating source for CO in N159W. On the other hand, mechanical heating by low-velocity C-type shocks with ~10 km s<sup>-1<sup/> appears sufficient enough to reproduce the observed warm CO.
Item Description:Gesehen am 17.06.2020
Physical Description:Online Resource
ISSN:1432-0746
DOI:10.1051/0004-6361/201628098

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