1994A&A...285..631G

Hα line profiles at both high spectral and angular resolutions were obtained at three 2.6' slit length positions over central and northern regions of the NGC2359 system of nebulae around the WR star HD56925. The main outer ring (4.2' in diameter) expands radially at a velocity ≃26 km/s. We show that this system results from the effects of the stellar wind and radiation field from a star with an initial main sequence mass of about 25 M_☉ as it evolves to its present WR phase. The present dynamics can be reconciled with this evolution only if the stellar wind bubbles blown in the fast wind stages are momentum rather than energy driven. This implies very clumpy circumstellar material where enhanced radiative losses at interfaces between clumps and shocked stellar winds radiate away most of the wind kinetic energy. A high velocity component observed at one point may result from local dynamical effects associated with enhanced cooling.