Issue |
A&A
Volume 612, April 2018
|
|
---|---|---|
Article Number | L5 | |
Number of page(s) | 5 | |
Section | Letters to the Editor | |
DOI | https://doi.org/10.1051/0004-6361/201832654 | |
Published online | 03 May 2018 |
Letter to the Editor
Formation of the terrestrial planets in the solar system around 1 au via radial concentration of planetesimals
1
Division of Theoretical Astronomy, National Astronomical Observatory of Japan,
2-21-1, Osawa,
Mitaka,
181-8588
Tokyo, Japan
e-mail: masahiro.ogihara@nao.ac.jp
2
School of Arts & Sciences, University of Tokyo,
3-8-1, Komaba, Meguro,
153-8902
Tokyo, Japan
2
Laboratoire Lagrange, Université Côte d’Azur, Observatoire de la Côte d’Azur, CNRS,
Blvd de l’Observatoire, CS 34229,
06304
Nice Cedex 4, France
Received:
17
January
2018
Accepted:
29
March
2018
Context. No planets exist inside the orbit of Mercury and the terrestrial planets of the solar system exhibit a localized configuration. According to thermal structure calculation of protoplanetary disks, a silicate condensation line (~1300 K) is located around 0.1 au from the Sun except for the early phase of disk evolution, and planetesimals could have formed inside the orbit of Mercury. A recent study of disk evolution that includes magnetically driven disk winds showed that the gas disk obtains a positive surface density slope inside ~1 au from the central star. In a region with positive midplane pressure gradient, planetesimals undergo outward radial drift.
Aims. We investigate the radial drift of planetesimals and type I migration of planetary embryos in a disk that viscously evolves with magnetically driven disk winds. We show a case in which no planets remain in the close-in region.
Methods. Radial drifts of planetesimals are simulated using a recent disk evolution model that includes effects of disk winds. The late stage of planet formation is also examined by performing N-body simulations of planetary embryos.
Results. We demonstrate that in the middle stage of disk evolution, planetesimals can undergo convergent radial drift in a magnetorotational instability (MRI)-inactive disk, in which the pressure maximum is created, and accumulate in a narrow ring-like region with an inner edge at ~0.7 au from the Sun. We also show that planetary embryos that may grow from the narrow planetesimal ring do not exhibit significant type I migration in the late stage of disk evolution.
Conclusions. The origin of the localized configuration of the terrestrial planets of the solar system, in particular the deficit of close-in planets, can be explained by the convergent radial drift of planetesimals in disks with a positive pressure gradient in the close-in region.
Key words: planets and satellites: formation / protoplanetary disks / planet–disk interactions / methods: numerical
© ESO 2018
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