Radiation-pressure-driven sub-Keplerian rotation of the disc around the AGB star L2 Pup

Abstract

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 cannot 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 $\sim 5$kms${}^{-1}$, 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.

Resubmitted to MNRAS after minor revisions

References in corpus (8)

• Too little radiation pressure on dust in the winds of oxygen-rich AGB stars
• Dust flow in gas disks in the presence of embedded planets
• Unexpectedly large mass loss during the thermal pulse cycle of the red giant R Sculptoris!
• ALMA data suggest the presence of a spiral structure in the inner wind of CW Leo
• Molecular shells in IRC+10216: tracing the mass loss history
• ALMA observations of the nearby AGB star L2 Puppis - I. Mass of the central star and detection of a candidate planet
• Radiation-hydrodynamical simulations of massive star formation using Monte Carlo radiative transfer: I. Algorithms and numerical methods
• An edge-on translucent dust disk around the nearest AGB star L2 Puppis - VLT/NACO spectro-imaging from 1.04 to 4.05 microns and VLTI interferometry

Cited by in corpus (5)

• Circumbinary discs for stellar population models
• Atomium: The astounding complexity of the near circumstellar environment of the M-type AGB star R Hydrae. I. Morpho-kinematical interpretation of CO and SiO emission
• Revealing new features of the millimetre emission of the circumbinary envelope of Mira Ceti
• Morpho-kinematics of the wind of AGB star L${}_2$ Pup
• The fate of Earth during the Sun's giant phases: New constraints from ab initio tidal modelling and AGB mass loss