1996A&A...309..629D

We report new spectroscopic observations of He 2-104 (the southern crab). The Balmer decrement indicates a reddening corresponding to a colour excess E(B-V)=1.2mag. The main body of the ionized region has an important density stratification with values ranging from 10³cm^–3 up to 6-7x10⁶cm^–3, shown by a robust correlation between density and the ionization potential of the preceding ion. The average electron temperature through that region is about 13000K. Our data suggests only a modest enhancement of He and N. The Stoy temperature of the hot star is of the order of 30000K, suggesting an early evolutionary stage for the planetary.