Issue |
A&A
Volume 652, August 2021
|
|
---|---|---|
Article Number | A104 | |
Number of page(s) | 27 | |
Section | Planets and planetary systems | |
DOI | https://doi.org/10.1051/0004-6361/202141139 | |
Published online | 17 August 2021 |
Planet formation in stellar binaries: global simulations of planetesimal growth
1
Max-Planck-Institut für Extraterrestrische Physik,
85748
Garching,
Germany
e-mail: ksilsbee@mpe.mpg.de
2
Department of Applied Mathematics and Theoretical Physics, University of Cambridge,
Cambridge
CB3 0WA,
UK
3
Institute for Advanced Study,
Einstein Drive,
Princeton,
NJ
08540,
USA
Received:
20
April
2021
Accepted:
21
June
2021
Planet formation around one component of a tight, eccentric binary system such as γ Cephei (with semimajor axis around 20 AU) is theoretically challenging because of destructive high-velocity collisions between planetesimals. Despite this fragmentation barrier, planets are known to exist in such (so-called S-type) orbital configurations. Here we present a novel numerical framework for carrying out multi-annulus coagulation-fragmentation calculations of planetesimal growth, which fully accounts for the specifics of planetesimal dynamics in binaries, details of planetesimal collision outcomes, and the radial transport of solids in the disk due to the gas drag-driven inspiral. Our dynamical inputs properly incorporate the gravitational effects of both the eccentric stellar companion and the massive non-axisymmetric protoplanetary disk in which planetesimals reside, as well as gas drag. We identify a set of disk parameters that lead to successful planetesimal growth in systems such as γ Cephei or α Centauri starting from 1 to 10 km size objects. We identify the apsidal alignment of a protoplanetary disk with the binary orbit as one of the critical conditions for successful planetesimal growth: It naturally leads to the emergence of a dynamically quiet location in the disk (as long as the disk eccentricity is of order several percent), where favorable conditions for planetesimal growth exist. Accounting for the gravitational effect of a protoplanetary disk plays a key role in arriving at this conclusion, in agreement with our previous results. These findings lend support to the streaming instability as the mechanism of planetesimal formation. They provide important insights for theories of planet formation around both binary and single stars, as well as for the hydrodynamic simulations of protoplanetary disks in binaries (for which we identify a set of key diagnostics to verify).
Key words: planets and satellites: formation / protoplanetary disks / planet-disk interactions / planet-star interactions / planets and satellites: dynamical evolution and stability / binaries: general
© K. Silsbee and R. R. Rafikov 2021
Open Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Open Access funding provided by Max Planck Society.
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