It looks bell-shaped. Is that just an illusion?
I think the "bell shape" is more an outline of where the x-ray emissions are taking place. There is shocked material swirling around the star's equator, and also being spun out along the magnetic fields at either "jet". Maybe one jet is impacting more gas and dust than the other, or we're seeing through the material at an angle. The gas and dust become so hot they glow in x-rays; thus the bell shape. It's there, but not in visible light.
Anyway, that's my analysis, FWIW.
Hubble image in visible light:
And multiple x-ray images from Chandra:
