Planet populations inferred from debris discs

Abstract

We know little about the outermost exoplanets in planetary systems because our detection methods are insensitive to moderate-mass planets on wide orbits. However, debris discs can probe the outer-planet population because dynamical modelling of observed discs can reveal properties of perturbing planets. We use four sculpting and stirring arguments to infer planet properties in 178 debris-disc systems from the ISPY, LEECH, and LIStEN planet-hunting surveys. Similar analyses are often conducted for individual discs, but we consider a large sample in a consistent manner. We aim to predict the population of wide-separation planets, gain insight into the formation and evolution histories of planetary systems, and determine the feasibility of detecting these planets in the near future. We show that a ‘typical’ cold debris disc likely requires a Neptune- to Saturn-mass planet at 10–100 au, with some needing Jupiter-mass perturbers. Our predicted planets are currently undetectable, but modest detection-limit improvements (e.g. from JWST) should reveal many such perturbers. We find that planets thought to be perturbing debris discs at late times are similar to those inferred to be forming in protoplanetary discs, so these could be the same population if newly formed planets do not migrate as far as currently thought. Alternatively, young planets could rapidly sculpt debris before migrating inwards, meaning that the responsible planets are more massive (and located farther inwards) than debris-disc studies assume. We combine self-stirring and size-distribution modelling to show that many debris discs cannot be self-stirred without having unreasonably high masses; planet- or companion-stirring may therefore be the dominant mechanism in many (perhaps all) debris discs. Finally, we provide catalogues of planet predictions and identify promising targets for future planet searches.

Multiwavelength Vertical Structure in the AU Mic Debris Disk: Characterizing the Collisional Cascade

“…Recent work by Pearce et al (2022) found, after adopting an inner disk radius for the AU Mic system of 28.7 ± 0.3 au, that a planet with a mass of 0.44 ± 0.03 M Jup and semimajor axis of 21.9 ± 0.3 au would be able to "sculpt" the inner part of the AU Mic debris disk. Since our model yields a different inner radius than in Pearce et al (2022), we recalculated this planet mass and radius using their publicly available code, 13 finding that a planet with a minimum mass of 0.34 ± 0.03 M Jup and maximum semimajor axis of -+ 17.0 0.3 0.7 au would be able to truncate the inner part of the disk that is modeled in this work.…”

ALMA Images the Eccentric HD 53143 Debris Disk

“…surface area, relative to the star (2×10 −4 ) (Moór et al 2006). Herschel PACS observations at 70 and 160 µm marginally resolved a bright ring with radius ∼ 54 AU and width 39 AU that appeared elongated to the NW and SE (Marshall et al 2021;Pearce et al 2022). However, due to Herschel's poor spatial resolution the exact geometry of the disk remained unclear.…”

Eccentric debris belts reveal the dynamical history of the companion exoplanet

“…The current structure of these debris belts has largely been shaped by their interaction with the surrounding planets, not only through the violent clearing of the orbital paths, but also through more subtle resonant and secular processes. Similarly, we expect that the structure of extrasolar debris belts can help us infer the presence of planetary perturbers and their dynamical E-mail:lbr63@cornell.edu history (e.g., Raymond et al 2011;Pearce et al 2022;Guo & Kokubo 2022).…”