Kuiper Belt-Like Hot and Cold Populations of Planetesimal Inclinations in the $\beta$ Pictoris Belt Revealed by ALMA

Abstract

The inclination distribution of the Kuiper belt provides unique constraints on its origin and dynamical evolution, motivating vertically resolved observations of extrasolar planetesimal belts. We present ALMA observations of millimeter emission in the near edge-on planetesimal belt around $\beta$ Pictoris, finding that the vertical distribution is significantly better described by the sum of two Gaussians compared to a single Gaussian. This indicates that, as for the Kuiper belt, the inclination distribution of $\beta$ Pic's belt is better described by the sum of dynamically hot and cold populations rather than a single component. The hot and cold populations have RMS inclinations of 8.9${}_{-0.5}^{+0.7}$ and 1.1${}_{-0.5}^{+0.5}$ degrees. We also report that an axisymmetric belt model provides a good fit to new and archival ALMA visibilities, and confirm that the midplane is misaligned with respect to $\beta$ Pic b's orbital plane. However, we find no significant evidence for either the inner disk tilt observed in scattered light and CO emission or the South-West/North-East (SW/NE) asymmetry previously reported for millimeter emission. Finally, we consider the origin of the belt's inclination distribution. Secular perturbations from $\beta$ Pic b are unlikely to provide sufficient dynamical heating to explain the hot population throughout the belt's radial extent, and viscous stirring from large bodies within the belt alone cannot reproduce the two populations observed. This argues for an alternative or additional scenario, such as planetesimals being born with high inclinations, or the presence of a `$\beta$ Pic c' planet, potentially migrating outwards near the belt's inner edge.

19 pages, 12 figures; Accepted for publication in AJ

References in corpus (9)

• Molecular Gas Clumps from the Destruction of Icy Bodies in the $\beta$ Pictoris Debris Disk
• HST/ACS Multiband Coronagraphic Imaging of the Debris Disk around Beta Pictoris
• Do Two Temperature Debris Disks Have Multiple Belts?
• Exocometary gas structure, origin and physical properties around $\beta$ Pictoris through ALMA CO multi-transition observations
• Planetary chaotic zone clearing: destinations and timescales
• The Inner Disk Structure, Disk-Planet Interactions, and Temporal Evolution in the Beta Pictoris System: A Two-Epoch HST/STIS Coronagraphic Study
• Dynamics and Accretion of Planetesimals
• Very deep images of the innermost regions of the beta Pictoris debris disc at Lp
• VLT/NACO coronagraphic observations of fine structures in the disk of beta Pictoris

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