Interstellar molecules in the large magellanic cloud.

The results of a mm-wave molecular line search in the Large Magellanic Cloud are presented. The observations were done with the SEST in the area of the N159 complex of HII regions. Isotopomers of CO, CS, SO, CN, HCN, HNC, HCO+ and H2CO have been detected. All observed isotopic intensity ratios are consistent with small optical depths provided that abundance ratios typical of the Galactic disc hold for the interstellar gas in N159. The data indicate a 12C/13C abundance ratio of 50−20+25. The 18O/17O abundance ratio is observed to be about a factor of 2 lower than in the Galaxy, and another factor of 2 lower than in starburst galaxies. Normalized to the CO intensity, most lines detected in N159 are weaker than observed in the Galaxy. The only exception is HCO+, which also shows a large emission extent. Estimates of fractional abundances indicate that those of N159 typically are a factor of 10, or more, lower than in the Galaxy. [ABSTRACT FROM AUTHOR]

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