The detection of CH in external galaxies

Abstract

The 3264-MHz transition of CH has been detected in three galaxies (the Large Magellanic Cloud, NGC 4945 and NGC 5128) and possibly in a fourth (NGC 253). The line profiles were similar to those for H2CO. The 3335-MHz transition was detected in one (LMC) and possibly another (NGC4945). With the exception of NGC5128, the line/continuum ratios are similar to those in our Galaxy. The results suggest an overabundance of CH relative to H2CO and OH in a molecular cloud in NGC 5128 which is probably located well in front of the nucleus.