Recent CO studies of spiral galaxy NGC 4258 have revealed a close relationship between the molecular gas and the anomalous arms, recently interpreted as jets (Cecil et al. 1992, Martin et al. 1990). An IRAM single dish study by Krause et al. (1991) showed the CO to be concentrated around the Hα arms. Interferometrie imaging of the inner 1’ by Martin et al. (1990) showed the molecular gas confining the arms; they suggested that the jet had initially plowed a tunnel through the disk gas, producing a free path for subsequent ejections. This data also shows strong evidence for a jet-cloud collision along the N W arm (Piante et al. 1991).
To learn more about the jets, we are motivated to exploit the jet-gas relationship with multi-field imaging of the CO along the anomalous arms using the Nobeyama Millimeter Array. We present preliminary results from our first 60” field, centered on the SE Hα arm, 43.5” from the nucleus. Observations in the two most compact configurations (C and D) produced a 4” x 6” beam.