Planetesimal and planet formation in transient dust traps

¹ ELTE Eötvös Loránd University, Institute of Physics and Astronomy, Department of Astronomy, 1117 Budapest, Pázmány Péter sétány 1/A, Hungary
e-mail: Zs.Sandor@astro.elte.hu
² Konkoly Observatory, HUN-REN Research Centre for Astronomy and Earth Sciences, Konkoly-Thege Miklós út 15-17, 1121 Budapest, Hungary
³ CSFK, MTA Centre of Excellence, Konkoly-Thege Miklós út 15-17, 1121 Budapest, Hungary
e-mail: regaly.zsolt@csfk.org
⁴ Astrophysical Institute of La Plata, National Scientific and Technical Research Council and National University of La Plata, Paseo del Bosque s/n, 1900 La Plata, Argentina
e-mail: oguilera@fcaglp.unlp.edu.ar
⁵ Millennium Nucleus of Planetary Formation (NPF), Chile
⁶ New Mexico State University, Department of Astronomy, PO Box 30001 MSC 4500, Las Cruces, NM 88001, USA

Received: 30 July 2023
Accepted: 16 February 2024

Abstract

Context. The ring-like structures in protoplanetary discs that are observed in the cold dust emission by ALMA might be explained by dust aggregates trapped aerodynamically in pressure maxima.

Aims. We investigate the effect of a transient pressure maximum that develops between two regimes with different turbulent levels. We study how such a pressure maximum collects dust aggregates and transforms them into large planetesimals and Moon-mass cores that can further grow into a few Earth-mass planets by pebble accretion, and eventually into giant planets by accreting a gaseous envelope.

Methods. We developed a numerical model, incorporating the evolution of a gaseous disc, the growth and transport of pebbles, N-body interactions of growing planetary cores, and their backreaction to a gas disc by opening a partial gap. Planetesimal formation by streaming instability is parametrised in our model.

Results. A transient pressure maximum efficiently accumulates dust particles that can grow larger than millimetre-sized. If this happens, dust aggregates can be transformed by the streaming instability process into large planetesimals, which can grow further by pebble accretion according to our assumptions. As the gas evolves towards a steady state, the pressure maximum vanishes, and the concentrated pebbles not transformed into planetesimals and accreted by the growing planet drift inward. During this inward drift, if the conditions of the streaming instability are met, planetesimals are formed in the disc within a wide radial range.

Conclusions. A transient pressure maximum is a favourable place for planetesimal and planet formation during its lifetime and the concentration of pebbles induces continuous formation of planetesimals even after its disappearance. In addition, the formation of a planet can trigger the formation of planetesimals over a wide area of the protoplanetary disc.