Growing the seeds of pebble accretion through planetesimal accretion
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Growing the seeds of pebble accretion through planetesimal accretion. / Lorek, Sebastian; Johansen, Anders.
In: Astronomy & Astrophysics, Vol. 666, A108, 2022.Research output: Contribution to journal › Journal article › Research › peer-review
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TY - JOUR
T1 - Growing the seeds of pebble accretion through planetesimal accretion
AU - Lorek, Sebastian
AU - Johansen, Anders
PY - 2022
Y1 - 2022
N2 - We explore the growth of planetary embryos by planetesimal accretion up to and beyond the point at which pebble accretion becomes efficient at the so-called Hill-transition mass. Both the transition mass and the characteristic mass of planetesimals that formed by the streaming instability increase with increasing distance from the star. We developed a model for the growth of a large planetesimal (embryo) embedded in a population of smaller planetesimals formed in a filament by the streaming instability. The model includes in a self-consistent way the collisional mass growth of the embryo, the fragmentation of the planetesimals, the velocity evolution of all involved bodies, and the viscous spreading of the filament. We find that the embryo accretes all available material in the filament during the lifetime of the protoplanetary disc only in the inner regions of the disc. In contrast, we find little or no growth in the outer parts of the disc beyond 5-10 AU. Overall, our results demonstrate very long timescales for collisional growth of planetesimals in the regions of the protoplanetary disc in which giant planets form. This means that in order to form giant planets in cold orbits, pebble accretion must act directly on the largest bodies present in the initial mass function of planetesimals with little or no help from mutual collisions.
AB - We explore the growth of planetary embryos by planetesimal accretion up to and beyond the point at which pebble accretion becomes efficient at the so-called Hill-transition mass. Both the transition mass and the characteristic mass of planetesimals that formed by the streaming instability increase with increasing distance from the star. We developed a model for the growth of a large planetesimal (embryo) embedded in a population of smaller planetesimals formed in a filament by the streaming instability. The model includes in a self-consistent way the collisional mass growth of the embryo, the fragmentation of the planetesimals, the velocity evolution of all involved bodies, and the viscous spreading of the filament. We find that the embryo accretes all available material in the filament during the lifetime of the protoplanetary disc only in the inner regions of the disc. In contrast, we find little or no growth in the outer parts of the disc beyond 5-10 AU. Overall, our results demonstrate very long timescales for collisional growth of planetesimals in the regions of the protoplanetary disc in which giant planets form. This means that in order to form giant planets in cold orbits, pebble accretion must act directly on the largest bodies present in the initial mass function of planetesimals with little or no help from mutual collisions.
KW - methods
KW - numerical
KW - planets and satellites
KW - formation
KW - DUST GROWTH PEBBLES
KW - SIZE DISTRIBUTION
KW - OLIGARCHIC GROWTH
KW - EVOLUTION
KW - DISK
KW - MASS
KW - RUNAWAY
KW - ORIGIN
KW - GAS
KW - ICE
U2 - 10.1051/0004-6361/202244333
DO - 10.1051/0004-6361/202244333
M3 - Journal article
VL - 666
JO - Astronomy & Astrophysics
JF - Astronomy & Astrophysics
SN - 0004-6361
M1 - A108
ER -
ID: 325010206