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

S. PARON; M.E. ORTEGA; C. FARIÑA; M. CUNNINGHAM; P. A. JONES; M. RUBIO

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY

WILEY-BLACKWELL PUBLISHING, INC

Lugar: Londres; Año: 2016 vol. 455

0035-8711

We present results obtained towards the H II regions N159, N166, andN132 from the emission of several molecular lines in the 345 GHz window.Using Atacama Submillimetre Telescope Experiment, we mapped a 2.4 arcmin x 2.4 arcmin region towards the molecular cloud N159-W in the 13CO J=3-2 line and observed several molecular lines at aninfrared (IR) peak very close to a massive young stellar object. 12CO and 13CO J=3-2 were observed towards twopositions in N166 and one position in N132. The 13CO J=3-2map of the N159-W cloud shows that the molecular peak is shiftedsouth-west compared to the peak of the IR emission. Towards the IR peak,we detected emission from HCN, HNC, HCO+, C2H J=4-3, CS J=7-6, and tentatively C18O J=3-2. This is thefirst reported detection of these molecular lines in N159-W. Theanalysis of the C2H line yields more evidence supporting thatthe chemistry involving this molecular species in compact and/or UC H IIregions in the Large Magellanic Cloud should be similar to that inGalactic ones. A non-LTE (local thermodynamic equilibrium) study of theCO emission suggests the presence of both cool and warm gas in theanalysed region. The same analysis for the CS, HCO+, HCN, andHNC shows that it is very likely that their emissions arise mainly fromwarm gas with a density between 5 x 10^5 to some10^6 cm^(-3). The obtained HCN/HNC abundance ratiogreater than 1 is compatible with warm gas and with an star-formingscenario. From the analysis of the molecular lines observed towards N132and N166, we propose that both regions should have similar physicalconditions, with densities of about 10^3 cm^(-3).