1995A&A...304..475C

We present high and low resolution spectroscopy and narrow-band imaging of the unusual bipolar outflow source NGC 6537. As a consequence, we are able for the first time to construct large scale velocity maps of this source; note the presence of strongly variable core outflow densities, rising to a peak value n_e∼1.7x10⁴cm^–3; find evidence for substantial core ionization stratification; and demonstrate the presence of a spatially extended, intermediate velocity wind extending over a range {DELTA}v_I≃700km/s, together with a more tightly constrained component having {DELTA}v≃4400km/s. This latter wind appears co-spatial with the slower, higher intensity core emission, and may be responsible for driving denser clumps of material to a typical velocity v_exp∼18km/s. Temperatures appear to vary significantly over the core, from a peak value T_e≃1.0x10⁴K close to the nucleus, to ≃0.9x10⁴K for projected radial offsets of 5", whilst extinction is more or less constant, yielding a mean estimate A_v≃3.4±0.2mag. Application of a shock outflow model suggests that most of these features are readily explained providing wind mass-loss rates are of order {dot}(M)_*∼6x10^–8-6x10^–7M_☉/yr, and the flow is strongly collimated by an interior disk. In particular, we are able to provide excellent simulations for both the complex kinematics, and unusual bipolar configuration.