  Planet formation models begin with proto-embryos and planetesimals already
fully formed, missing out a crucial step, the formation of
planetesimals/proto-embryos. In this work, we include prescriptions for
planetesimal and proto-embryo formation arising from pebbles becoming trapped
in short-lived pressure bumps, in thermally evolving viscous discs to examine
the sizes and distributions of proto-embryos and planetesimals throughout the
disc. We find that planetesimal sizes increase with orbital distance, from ~10
km close to the star to hundreds of kilometres further away. Proto-embryo
masses are also found to increase with orbital radius, ranging from $10^{-6}
M_{\rm \oplus}$ around the iceline, to $10^{-3} M_{\rm \oplus}$ near the orbit
of Pluto. We include prescriptions for pebble and planetesimal accretion to
examine the masses that proto-embryos can attain. Close to the star,
planetesimal accretion is efficient due to small planetesimals, whilst pebble
accretion is efficient where pebble sizes are fragmentation limited, but
inefficient when drift dominated due to low accretion rates before the pebble
supply diminishes. Exterior to the iceline, planetesimal accretion becomes
inefficient due to increasing planetesimal eccentricities, whilst pebble
accretion becomes more efficient as the initial proto-embryo masses increase,
allowing them to significantly grow before the pebble supply is depleted.
Combining both scenarios allows for more massive proto-embryos at larger
distances, since the accretion of planetesimals allows pebble accretion to
become more efficient, allowing giant planet cores to form at distances upto 10
au. By including more realistic initial proto-embryo and planetesimal sizes, as
well as combined accretion scenarios, should allow for a more complete
understanding in the beginning to end process of how planets and planetary
systems form.
