High Velocity Bipolar Outflows in Planetary Nebulae: NGC 6537 and Hb 5
Bipolar symmetry characterizes the morphology of a large number of objects thought to be protoplahetary nebulae. Among these, NGC 6537 and Hb 5 were observed on July 1991 at the 3.5m NTT telescope of the European Southern Observatory, using the EMMI multimode instrument. Hα+[NII] images (Fig. 1) allowed accurate information on the faintest structure of the external region of these nebulae: the line emission extends out to 120″ from the center of NGC 6537 and out to 30″ in Hb 5 (compared to the nebular radii of 40″ and 10″, respectively, quoted in the literature). An interesting feature of the morphology of both nebulae is the point-symmetrical distribution of line emission characterizing their brightest regions.
- Meaburn, J., Walsh, J.R.: 1980, M.N.R.A.S. 103, 361Google Scholar