We study the sub-Keplerian rotation and dust content of the circumstellar material around the asymptotic giant branch ( AGB ) star L _ { 2 } Puppis .
We find that the thermal pressure gradient alone can not explain the observed rotation profile .
We find that there is a family of possible dust populations for which radiation pressure can drive the observed sub-Keplerian rotation .
This set of solutions is further constrained by the spectral energy distribution ( SED ) of the system , and we find that a dust-to-gas mass ratio of \sim 10 ^ { -3 } and a maximum grain size that decreases radially outwards can satisfy both the rotation curve and SED .
These dust populations are dynamically tightly coupled to the gas azimuthally .
However grains larger than \sim 0.5 \mu m are driven outward radially by radiation pressure at velocities \sim 5 km s ^ { -1 } , which implies a dust replenishment rate of \sim 3 \times 10 ^ { -9 } M _ { \odot } yr ^ { -1 } .
This replenishment rate is consistent with observational estimates to within uncertainties .
Coupling between the radial motion of the dust and gas is weak and hence the gas does not share in this rapid outward motion .
Overall we conclude that radiation pressure is a capable and necessary mechanism to explain the observed rotation profile of L _ { 2 } Pup , and offers other additional constraints on the dust properties .