DETECTION OF THE CARBON-MONOXIDE ION (CO-MEDIUM AND A PLANETARY-NEBULA() IN THE INTERSTELLAR)

We report detection of the carbon monoxide ion (CO+) in the interstell ar medium (M17SW) and a planetary nebula (NGC 7027). These detections are based on observations of three millimeter and submillimeter transi tions in M17SW and one in NGC 7027. Chemical models suggest that CO+ s hould be most abundant where complex molecules are least likely to be present. In our search for CO+ we therefore minimized the chance of co nfusion while maximizing the probability of detection by observing reg ions whose chemistry is dominated by the effects of ultraviolet radiat ion.