English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

The amount of nebular gas that a planet can bind is limited by its coolingrate, which is set by the opacity of its envelope. Accreting dust and pebblescontribute to the envelope opacity and, thus, influence the outcome of planetformation. Our aim is to model the size evolution and opacity contribution ofsolids inside planetary envelopes. We then use the resultant opacity relationsto study emergent trends in planet formation. We design a model for the opacityof solids in planetary envelopes that accounts for the growth, fragmentationand erosion of pebbles during their sedimentation. We formulate analyticalexpressions for the opacity of pebbles and dust and map out their trends as afunction of depth, planet mass, distance and accretion rate. We find that theaccretion of pebbles rather than planetesimals can produce fully convectiveenvelopes, but only in lower-mass planets that reside in the outer disk or inthose that are accreting pebbles at a high rate. In these conditions, pebblesizes are limited by fragmentation and erosion, allowing them to pile up in theenvelope. At higher planetary masses or reduced accretion rates, a differentregime applies where the sizes of sedimenting pebbles are only limited by theirrate of growth. The opacity in this growth-limited regime is much lower,steeply declines with depth and planet mass but is invariant with the pebblemass flux. Our results imply that the opacity of a forming planetary envelopecan not be approximated by a value that is constant with either depth or planetmass. When applied to the Solar System, we argue that Uranus and Neptune couldnot have maintained a sufficiently high opacity to avoid runaway gas accretionunless they both experienced sufficiently rapid accretion of solids and formedlate.

How planets grow by pebble accretion IV: Envelope opacity trends from sedimenting dust and pebbles