Extrasolar Kuiper belts

Abstract

Extrasolar debris disks are the dust disks found around nearby main sequence stars arising from the break-up of asteroids and comets orbiting the stars. Far-IR surveys (e.g., with Herschel) showed that ∼ 20% of stars host detectable dust levels. While dust temperatures suggest a location at 10s of au comparable with our Kuiper belt, orders of magnitude more dust is required implying a planetesimal population more comparable with the primordial Kuiper belt. High resolution imaging (e.g., with ALMA) has mapped the nearest and brightest disks, providing evidence for structures shaped by an underlying planetary system. Some of these are analogous to structures in our own Kuiper belt (e.g., the hot and cold classical, resonant, scattered disk and cometary populations), while others have no Solar System counterpart. CO gas is seen in some debris disks, and inferred to originate in the destruction of planetesimals with a similar volatile-rich composition to Solar System comets. This chapter reviews our understanding of extrasolar Kuiper belts and of how our own Kuiper belt compares with those of neighbouring stars.

Global Modeling of Nebulae With Particle Growth, Drift, and Evaporation Fronts. III. Redistribution of Refractories and Volatiles

“…9). The EF-related banded structure, or enhancements outside the various "snow lines" in general, as well as significant radial dips in the metallicity seen in our models, may provide an explanation for ALMA observations that show well defined particle belts at large radii (Carrasco-González et al 2019;Segura-Cox et al 2020), or for the formation of "ExoKuiper belts" seen in revealed systems (Wyatt 2020).…”

“…Perhaps most striking is that most of the mass in the lowest α t model is in the vapor phase and close to the star, suggesting that this vast reservoir could eventually contribute to these bands as the disk cools and the vapor recondenses. Planetesimals that may form within these bands at an early time are resistant to inward migration as the EF itself evolves inwards, this may give rise to debris belts -"fossils" of a previous radial location of the EF -that may constantly produce pebbles and visible dust via collisions which may be reaccreted or drift inwards, as seen in the so-called "Exo-Kuiper Belts" seen in exoplanetary systems (Wyatt 2020).…”

Global Modeling of Nebulae with Particle Growth, Drift, and Evaporation Fronts. III. Redistribution of Refractories and Volatiles

“…Recall that most condensable material mass is in the vapor phase closer to the Sun for the lowest α t models (see Figure 9). The EF-related banded structure, or enhancements outside the various "snowlines" in general, as well as significant radial dips in the metallicity seen in our models, may provide an explanation for ALMA observations that show well-defined particle belts at large radii (Carrasco-González et al 2019;Segura-Cox et al 2020), or for the formation of "Exo-Kuiper Belts" seen in revealed systems (Wyatt 2020).…”

System-level fractionation of carbon from disk and planetesimal processing

“…3B. Given the expected variation in 26 Al content from system to system, it is interesting to look at extra-solar Kuiper Belts (Wyatt 2020), as it is now becoming possible to constrain the volatile content of planetesimals at 10s to 100s of au in a handful of systems (e.g., Marino et al 2016;Kral et al 2017). Constraints on the (CO+CO 2 ) mass content of planetesimals range from <1 to ≈35% (Wyatt 2020), broadly consistent with the ranges we find in e.g., Figs.…”