Seminar: Planet formation by pebble accretion

  • Date: –15:00
  • Location: Ångströmlaboratoriet, Lägerhyddsvägen 1 Hjorter’s room (Å73101)
  • Lecturer: Michiel Lambrechts, Lund University
  • Contact person: Sofia Ramstedt
  • Seminarium

ALMA surveys of star forming regions have revealed that a significant mass fraction of solids present in protoplanetary discs are mm in size. Such pebbles are expected to rapidly drift, within no more than a few Myr, towards the host star. Therefore, planet formation is a race against time. First, planetesimals will have to form efficiently and thereafter protoplanets need to grow to terrestrial sizes and larger to form the cores of gas giants. This is possible due to pebble accretion: the process whereby such protoplanets efficiently sweep up drifting pebbles, because gas drag causes incoming pebbles to efficiently spiral towards the planet. With N-body simulations, that include planet growth by pebble accretion and type-I migration, we show that the outcome of planet formation within the iceline results in either terrestrial-like planets or super-Earth systems. The outcome is sensitive to the available pebble mass reservoir to within a factor 2 (Lambrechts et al 2019a). We then highlight how the pebble isolation mass, which limits core growth to about 10 Earth masses around solar-like stars, sculpts the planetary distribution in population synthesis studies. Finally, we will address how planetary cores attract gaseous envelopes with the use of hydrodynamical simulations (Lambrechts et al 2019b).