A view of Large Magellanic Cloud HII regions N159, N132, and N166 through the 345 GHz window

Abstract

We present results obtained towards the HII regions N159, N166, and N132 from the emission of several molecular lines in the 345 GHz window. Using ASTE we mapped a 2.4' $\times$ 2.4' region towards the molecular cloud N159-W in the ${}^{13}$CO J=3-2 line and observed several molecular lines at an IR peak very close to a massive young stellar object. ${}^{12}$CO and ${}^{13}$CO J=3-2 were observed towards two positions in N166 and one position in N132. The ${}^{13}$CO J=3-2 map of the N159-W cloud shows that the molecular peak is shifted southwest compared to the peak of the IR emission. Towards the IR peak we detected emission from HCN, HNC, HCO${}^{+}$, C${}_2$H J=4-3, CS J=7-6, and tentatively C${}^{18}$O J=3-2. This is the first reported detection of these molecular lines in N159-W. The analysis of the C${}_2$H line yields more evidence supporting that the chemistry involving this molecular species in compact and/or UCHII regions in the LMC should be similar to that in Galactic ones. A non-LTE study of the CO emission suggests the presence of both cool and warm gas in the analysed region. The same analysis for the CS, HCO${}^{+}$, HCN, and HNC shows that it is very likely that their emissions arise mainly from warm gas with a density between $5\times 10^5$ to some $10^6$ cm${}^{-3}$. The obtained HCN/HNC abundance ratio greater than 1 is compatible with warm gas and with an star-forming scenario. From the analysis of the molecular lines observed towards N132 and N166 we propose that both regions should have similar physical conditions, with densities of about 10${}^3$ cm${}^{-3}$.

accepted in MNRAS (October 5, 2015)

References in corpus (10)

• An eclipsing binary distance to the Large Magellanic Cloud accurate to 2 per cent
• The Resolved Properties of Extragalactic Giant Molecular Clouds
• Molecular gas in extreme star-forming environments: the starbursts Arp220 and NGC6240 as case studies
• The interstellar gas-phase chemistry of HCN and HNC
• Ethynyl (C2H) in massive star formation: Tracing the initial conditions?
• Spitzer View of Young Massive Stars in the LMC HII Complexes. II. N159
• Sub-millimeter Observations of Giant Molecular Clouds in the Large Magellanic Cloud: Temperature and Density as Determined from J=3-2 and J=1-0 transitions of CO
• Velocity resolved [CII], [CI], and CO observations of the N159 star-forming region in the Large Magellanic Cloud: a complex velocity structure and variation of the column densities
• Submillimeter Line Emission from LMC N159W: a Dense, Clumpy PDR in a Low Metallicity Environment
• Spectroscopic study of the N159/N160 complex in the Large Magellanic Cloud

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• An ALMA Glimpse of Dense Molecular Filaments Associated with High-mass Protostellar Systems in the Large Magellanic Cloud
• DeGaS-MC: Dense Gas Survey in the Magellanic Clouds I -- An APEX survey of HCO+ and HCN(2-1) toward the LMC and SMC
• Physical conditions of the molecular gas in metal-poor galaxies
• Mapping the 13CO/C18O abundance ratio in the massive star forming region G29.96-0.02
• 12CO and 13CO J=3-2 observations toward N11 in the Large Magellanic Cloud
• An ALMA archival study of the clump mass function in the Large Magellanic Cloud
• Interrelations between Astrochemistry and Galactic Dynamics
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