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 formation of planetary cores must proceed rapidly in order for the giantplanets to accrete their gaseous envelopes before the dissipation of theprotoplanetary gas disc (<3 Myr). In orbits beyond 10 AU, direct accumulationof planetesimals by the cores is too slow. Fragments of planetesimals could beaccreted faster, but planetesimals are likely too large for fragmentation to beefficient, and resonant trapping poses a further hurdle. Here we insteadinvestigate the accretion of small pebbles (mm-cm sizes) that are the naturaloutcome of an equilibrium between the growth and radial drift of particles. Weconstruct a simplified analytical model of dust coagulation and pebble drift inthe outer disc, between 5 AU and 100 AU, which gives the temporal evolution ofthe solid surface density and the dominant particle size. These two keyquantities determine how core growth proceeds at various orbital distances. Wefind that pebble surface densities are sufficiently high to achieve theinside-out formation of planetary cores within the disc lifetime. The overallefficiency by which dust gets converted to planets can be high, close to 50 %for planetary architectures similar to the Solar System. Growth by pebbleaccretion in the outer disc is sufficiently fast to overcome catastrophic TypeI migration of the cores. These results require protoplanetary discs with largeradial extent (~100 AU) and assume a low number of initial seed embryos. Ourfindings imply that protoplanetary discs with low disc masses, as expectedaround low-mass stars (<1 M_sun), or with sub-solar dust-to-gas ratios, do noteasily form gas-giant planets (M > 100 M_E), but preferentially formNeptune-mass planets or smaller (< 10 M_E). This is consistent with exoplanetsurveys which show that gas giants are relatively uncommon around stars of lowmass or low metallicity.

Forming the cores of giant planets from the radial pebble flux in protoplanetary discs