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Journal Articles Monthly Notices of the Royal Astronomical Society Year : 2020

Insights into the planetary dynamics of HD 206893 with ALMA

S. Marino
  • Function : Author
A. Zurlo
  • Function : Author
V. Faramaz
  • Function : Author
Th Henning
  • Function : Author
G. M. Kennedy
  • Function : Author
L. Matrà
  • Function : Author
S. Pérez
  • Function : Author
L. A. Cieza
  • Function : Author
A. M. Hughes
  • Function : Author


Radial substructure in the form of rings and gaps has been shown to be ubiquitous among protoplanetary discs. This could be the case in exo-Kuiper belts as well, and evidence for this is emerging. In this paper, we present ALMA observations of the debris/planetesimal disc surrounding HD 206893, a system that also hosts two massive companions at 2 and 11 au. Our observations reveal a disc extending from 30 to 180 au, split by a 27 au wide gap centred at 74 au, and no dust surrounding the reddened brown dwarf (BD) at 11 au. The gap width suggests the presence of a 0.9MJup planet at 74 au, which would be the third companion in this system. Using previous astrometry of the BD, combined with our derived disc orientation as a prior, we were able to better constrain its orbit finding it is likely eccentric ($0.14^{+0.05}_{-0.04}$). For the innermost companion, we used radial velocity, proper motion anomaly, and stability considerations to show its mass and semimajor axis are likely in the ranges 4-100MJup and 1.4-4.5 au. These three companions will interact on secular time-scales and perturb the orbits of planetesimals, stirring the disc and potentially truncating it to its current extent via secular resonances. Finally, the presence of a gap in this system adds to the growing evidence that gaps could be common in wide exo-Kuiper belts. Out of six wide debris discs observed with ALMA with enough resolution, four to five show radial substructure in the form of gaps.
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Dates and versions

insu-03705173 , version 1 (27-06-2022)





S. Marino, A. Zurlo, V. Faramaz, J. Milli, Th Henning, et al.. Insights into the planetary dynamics of HD 206893 with ALMA. Monthly Notices of the Royal Astronomical Society, 2020, 498, pp.1319-1334. ⟨10.1093/mnras/staa2386⟩. ⟨insu-03705173⟩
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