Is There a Temperature Limit in Planet Formation at 1000 K?

TL;DR

This study investigates how high temperatures affect dust aggregation in protoplanetary disks, revealing a critical transition at 1000 K that influences planet formation processes.

Contribution

It provides experimental evidence of a temperature-dependent transition in dust aggregation, linking laboratory results to observed planetary system characteristics.

Findings

Dust tempered below 1000 K forms larger aggregates.

Temperature influences dust growth size by a factor of about 1.5.

The transition temperature aligns with temperatures of observed exoplanets.

Abstract

Dust drifting inward in protoplanetary disks is subject to increasing temperatures. In laboratory experiments, we tempered basaltic dust between 873 K and 1273 K and find that the dust grains change in size and composition. These modifications influence the outcome of self-consistent low speed aggregation experiments showing a transition temperature of 1000\,K. Dust tempered at lower temperatures grows to a maximum aggregate size of $2.02 \pm 0.06$ mm, which is $1.49 \pm 0.08$ times the value for dust tempered at higher temperatures. A similar size ratio of $1.75 \pm 0.16$ results for a different set of collision velocities. This transition temperature is in agreement with orbit temperatures deduced for observed extrasolar planets. Most terrestrial planets are observed at positions equivalent to less than 1000 K. Dust aggregation on the millimeter-scale at elevated temperatures might therefore be a key factor for terrestrial planet formation.