Post-collapse aggregate radius vs heliocentric distance. The hatched area marks the range of pebble sizes measured on 67 P by the CIVA camera on board Rosetta/Philae (Poulet et al. 2016). The square symbols show aggregate sizes at St_min. Large and small symbols are for 1 μm and 0.1 μm sized monomers, respectively. Symbols are filled if aggregates might trigger the streaming instability (Table 3). Dashed lines indicate the minimum size for aggregates with a given volume-filling factor to have St_min. ϕ₀ refers to the initial aggregate porosity (i.e. before compression).