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

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

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY

WILEY-BLACKWELL PUBLISHING, INC

Lugar: Londres; Año: 2016 vol. 455 p. 518 - 525

0035-8711

We present results obtained towards the HII regions N159, N166, and N132from the emission of several molecular lines in the 345 GHz window.Using ASTE we mapped a 2.4´ $imes$ 2.4´ region towards the molecularcloud N159-W in the $^{13}$CO J=3-2 line and observed several molecularlines 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 inN166 and one position in N132. The $^{13}$CO J=3-2 map of the N159-Wcloud shows that the molecular peak is shifted southwest compared to thepeak of the IR emission. Towards the IR peak we detected emission fromHCN, HNC, HCO$^{+}$, C$_{2}$H J=4-3, CS J=7-6, and tentatively C$^{18}$OJ=3-2. This is the first reported detection of these molecular lines inN159-W. The analysis of the C$_{2}$H line yields more evidencesupporting that the chemistry involving this molecular species incompact and/or UCHII regions in the LMC should be similar to that inGalactic ones. A non-LTE study of the CO emission suggests the presenceof both cool and warm gas in the analysed region. The same analysis forthe CS, HCO$^{+}$, HCN, and HNC shows that it is very likely that theiremissions arise mainly from warm gas with a density between $5 imes10^5$ to some $10^6$ 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$^{-3}$.