2012ApJ...749L...4L

We report the detection toward η Carinae of six new molecules, CO, CN, HCO⁺, HCN, HNC, and N₂H⁺, and of two of their less abundant isotopic counterparts, ¹³CO and H¹³CN. The line profiles are moderately broad (∼100 km/s), indicating that the emission originates in the dense, possibly clumpy, central arcsecond of the Homunculus Nebula. Contrary to previous claims, CO and HCO⁺ do not appear to be underabundant in η Carinae. On the other hand, molecules containing nitrogen or the ¹³C isotope of carbon are overabundant by about one order of magnitude. This demonstrates that, together with the dust responsible for the dimming of η Carinae following the Great Eruption, the molecules detected here must have formed in situ out of CNO-processed stellar material.