The first definite discoveries of extragalactic deuterium are reported .
DCO ^ { + } has been detected in three and DCN has been measured in one star-forming region of the Large Magellanic Cloud ( LMC ) .
While the HCO ^ { + } /DCO ^ { + } abundance ratios are found to be 19 \pm 3 , 24 \pm 4 , and 67 \pm 18 for N113 , N44BC and N159HW , respectively , a HCN/DCN abundance ratio of 23 \pm 5 is obtained for N113 .
These results are consistent with a gas temperature of about 20 K and a D/H ratio of about 1.5 \times 10 ^ { -5 } , consistent with that observed in the Galaxy .
If the cloud temperature is closer to 30 K , then a D/H ratio is required to be up to an order of magnitude larger .
Because this ratio provides a lower limit to the primordial D/H ratio , it indicates that the baryon mass density alone is unable to close the universe .