Anomalous [NII]-emission from Mz-3

Extract

We obtained high resolution spectra of the red [NII]-lines in the bipolar nebula Mz-3, This object probably is a protoplanetary nebula (see e.g. Lopez and Meaburn, 1983 and Meaburn and Walsh, 1985). The spectra were taken in July and September 1982 at La Silla using the Coudé Auxiliary Telescope (CAT) combined with the Coudé Echelle Spectrograph (CES). The resolution depending on the slit width was 30000 and 100000, respectively. Fig. 1 shows the [NII]-lines at 6583.6 and 6548.3 Å together with H_α. The structure of the 6583.6 Å line, which is quite complicated in detail, is dominated by two narrow peaks, similar to the profiles of circumstellar O H-masers. The profile varies strongly with the slit width and shows substantial differences between the observations in July and September. - The most striking result of our observations is that the intensity ratio 6584/6548 deviates strongly from the canonical value of 3 as shown in Fig. 2.