Europlanet Science Congress 2022
Palacio de Congresos de Granada, Spain
18 – 23 September 2022
Europlanet Science Congress 2022
Palacio de Congresos de Granada, Spain
18 September – 23 September 2022
EPSC Abstracts
Vol. 16, EPSC2022-114, 2022
https://doi.org/10.5194/epsc2022-114
Europlanet Science Congress 2022
© Author(s) 2022. This work is distributed under
the Creative Commons Attribution 4.0 License.

Giant Formation with Pebbles and Planetesimals

Andrin Kessler1, Yann Alibert1, Christoph Mordasini1, Alexandre Emsenhuber2, and Remo Burn3
Andrin Kessler et al.
  • 1University of Bern, Physics Institute, Space Research & Planetary Sciences, Switzerland (andrin.kessler@unibe.ch)
  • 2University Observatory, Ludwig-Maximilians University, Munich, Germany
  • 3Max-Planck-Institut für Astronomie, Heidelberg, Germany

Abstract

High-precision measurements of isotopes in meteorites suggest that the early population of small bodies in the Solar System has been separated into two reservoirs by the forming Jupiter, acting as a radial barrier for these 'planetesimals' [1]. In a proposed Jupiter formation scenario [2], the solid core must grow within 1 Myr to around 20 Earth masses, then stagnate its growth for 2-3 Myr and thus separating the planetesimal reservoirs, and finally grow to the final Jupiter mass stirring and mixing the inner and outer planetesimals. The fast and early core growth is efficiently facilitated by the accretion of small 'pebble-like' objects. In order to delay the otherwise inevitable rapid runaway gas accretion for an extended period of time after the pebble accretion stops, Jupiter is proposed to be heated by slower planetesimal accretion before finally becoming massive enough to accrete a large amount of gas, reaching its present day mass.

Motivated by this proposed formation scenario of Jupiter, we investigate the consequences of a combined pebble and planetesimal accretion model for the formation of giant planets and planet formation in general [3]. We modify the Bern model of planetary population synthesis [4] with a simple model of pebble formation and accretion [5]. In a single-planet population synthesis approach, we run the model on a thousand different initial protoplanetary disks in order to probe the effects of the two solid accretion mechanisms on a population level. To uncover the interplay of the two models, we vary the amount of pebbles with respect to planetesimals.

As shown in figure 1, it proves to be difficult to form giant planets from the accretion of pebbles and planetesimals whereas both mechanisms individually are able to form giants in suitable disks. We identify the remaining accretion of planetesimals after the stop of pebble accretion to be crucial for the formation pathway of a growing planet. The envelope heating due to the accretion of solids is shown to play a critical role for the accretion of gas. A combination of enhanced inward orbital migration and delayed runaway gas accretion strongly suppresses the formation of giants in disks containing both pebbles and planetesimals.

 

Figure 1: Planet mass over semi-major axis snapshot after 2 Gyr of evolution for populations of one thousand disks, containing one planet. The four, otherwise identical, populations start with either only planetesimals (left), 30% pebbles (middle left), 70% pebbles (middle right), or only pebbles (right).


References

[1] Kruijer T. S., Burkhardt C., Budde G., Kleine T., 2017, Proc. Natl. Acad. Sci., 114, 6712

[2] Alibert Y., Venturini J., Helled R., et al., 2018, Nature Astronomy, 2, 873

[3] Kessler A., et al., in prep.

[4] Emsenhuber A., Mordasini C., Burn R., et al., 2021, A&A, 656, A 69 

[5] Bitsch B., Lambrechts M., Johansen A., 2015b, A&A, 582, A 112

How to cite: Kessler, A., Alibert, Y., Mordasini, C., Emsenhuber, A., and Burn, R.: Giant Formation with Pebbles and Planetesimals, Europlanet Science Congress 2022, Granada, Spain, 18–23 Sep 2022, EPSC2022-114, https://doi.org/10.5194/epsc2022-114, 2022.

Discussion

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