The formation of wide <i>exoKuiper</i> belts from migrating dust traps

ABSTRACT The question of what determines the width Kuiper belt analogues (exoKuiper belts) is an open one. If solved, this understanding would provide valuable insights into architecture, dynamics, and formation exoplanetary systems. Recent observations by ALMA have revealed apparent paradox in field, presence radially narrow belts protoplanetary discs that are likely birthplaces planetesimals, exoKuiper nearly four times as wide mature parent planetesimals type debris disc indeed form these rings via streaming instability where dust trapped, we propose dichotomy could naturally arise if traps whilst migrating radially, e.g. caused a planet. Using evolution software dustpy, find initial trap conditions favour planetesimal formation, can still effectively accumulate moves. This leads to positive correlation between inward radial speed final width, forming up ∼100au over 10 Myr evolution. We show although most efficient low-viscosity (α = 10−4) with steep trigger instability, large widths observed constrain α values ≥4 × 10−4 at tens au, otherwise cannot migrate far enough. Additionally, spread radii be due different migration speeds (or lifetimes) starting locations, respectively. Our work serves first step link discs.