This two-lobed, or "propeller"-shaped, electron probability density distribution characterizes an atom in the state: n=3, l=3, m=-2. For this state there are no jets or disks at the "waist".

Above is a photograph of the planetary nebula called M1-92.

This is a schematic drawing of the planetary nebula NGC 6826. It is inferred to have a symmetric "propeller" shape, without much structure in the "waist" region.

Source:H.E. White, Physical Review, vol. 37, pg. 1419, 1931.

Source:Planetary Nebulae, Proceedings of the 180th Symposium of the IAU (8/26-8/30, 1996), ed. By H.J. Habing and H.J.G.L.M. Lamers, Kluwer, Dordrecht, 1996, Figure 1, pg. 370.

Source:Ronald Weinberger, in Planetary Nebulae, Proceedings of the 131st Symposium of the IAU, ed. By Silvia Torres-Peimbert, pp. 93- 103, Kluwer, Drodrecht, 1989 (Fig. 1, pg. 95).