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Title: RAPID FORMATION OF SATURN AFTER JUPITER COMPLETION

Abstract

We have investigated Saturn's core formation at a radial pressure maximum in a protoplanetary disk, which is created by gap opening by Jupiter. A core formed via planetesimal accretion induces the fragmentation of surrounding planetesimals, which generally inhibits further growth of the core by removal of the resulting fragments due to radial drift caused by gas drag. However, the emergence of the pressure maximum halts the drift of the fragments, while their orbital eccentricities and inclinations are efficiently damped by gas drag. As a result, the core of Saturn rapidly grows via accretion of the fragments near the pressure maximum. We have found that in the minimum-mass solar nebula, kilometer-sized planetesimals can produce a core exceeding 10 Earth masses within two million years. Since Jupiter may not have undergone significant type II inward migration, it is likely that Jupiter's formation was completed when the local disk mass has already decayed to a value comparable to or less than Jovian mass. The expected rapid growth of Saturn's core on a timescale comparable to or shorter than the observationally inferred disk lifetime enables Saturn to acquire the current amount of envelope gas before the disk gas is completely depleted. The high heatmore » energy release rate onto the core surface due to the rapid accretion of the fragments delays onset of runaway gas accretion until the core mass becomes somewhat larger than that of Jupiter, which is consistent with the estimate based on interior modeling. Therefore, the rapid formation of Saturn induced by gap opening of Jupiter can account for the formation of multiple gas giants (Jupiter and Saturn) without significant inward migration and larger core mass of Saturn than that of Jupiter.« less

Authors:
 [1];  [2];  [3]
  1. Department of Physics, Nagoya University, Nagoya, Aichi 464-8602 (Japan)
  2. Astronomy Department, University of California, Berkeley, CA 94720 (United States)
  3. Tokyo Institute of Technology, Ookayama, Meguro-ku, Tokyo 152-8551 (Japan)
Publication Date:
OSTI Identifier:
22092437
Resource Type:
Journal Article
Journal Name:
Astrophysical Journal
Additional Journal Information:
Journal Volume: 756; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0004-637X
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ASTRONOMY; ASTROPHYSICS; COMPUTERIZED SIMULATION; FRAGMENTATION; INCLINATION; JUPITER PLANET; LIFETIME; MASS; PROTOPLANETS; SATELLITES; SATURN PLANET; SOLAR NEBULA; SURFACES

Citation Formats

Kobayashi, Hiroshi, Ormel, Chris W., and Ida, Shigeru. RAPID FORMATION OF SATURN AFTER JUPITER COMPLETION. United States: N. p., 2012. Web. doi:10.1088/0004-637X/756/1/70.
Kobayashi, Hiroshi, Ormel, Chris W., & Ida, Shigeru. RAPID FORMATION OF SATURN AFTER JUPITER COMPLETION. United States. https://doi.org/10.1088/0004-637X/756/1/70
Kobayashi, Hiroshi, Ormel, Chris W., and Ida, Shigeru. Sat . "RAPID FORMATION OF SATURN AFTER JUPITER COMPLETION". United States. https://doi.org/10.1088/0004-637X/756/1/70.
@article{osti_22092437,
title = {RAPID FORMATION OF SATURN AFTER JUPITER COMPLETION},
author = {Kobayashi, Hiroshi and Ormel, Chris W. and Ida, Shigeru},
abstractNote = {We have investigated Saturn's core formation at a radial pressure maximum in a protoplanetary disk, which is created by gap opening by Jupiter. A core formed via planetesimal accretion induces the fragmentation of surrounding planetesimals, which generally inhibits further growth of the core by removal of the resulting fragments due to radial drift caused by gas drag. However, the emergence of the pressure maximum halts the drift of the fragments, while their orbital eccentricities and inclinations are efficiently damped by gas drag. As a result, the core of Saturn rapidly grows via accretion of the fragments near the pressure maximum. We have found that in the minimum-mass solar nebula, kilometer-sized planetesimals can produce a core exceeding 10 Earth masses within two million years. Since Jupiter may not have undergone significant type II inward migration, it is likely that Jupiter's formation was completed when the local disk mass has already decayed to a value comparable to or less than Jovian mass. The expected rapid growth of Saturn's core on a timescale comparable to or shorter than the observationally inferred disk lifetime enables Saturn to acquire the current amount of envelope gas before the disk gas is completely depleted. The high heat energy release rate onto the core surface due to the rapid accretion of the fragments delays onset of runaway gas accretion until the core mass becomes somewhat larger than that of Jupiter, which is consistent with the estimate based on interior modeling. Therefore, the rapid formation of Saturn induced by gap opening of Jupiter can account for the formation of multiple gas giants (Jupiter and Saturn) without significant inward migration and larger core mass of Saturn than that of Jupiter.},
doi = {10.1088/0004-637X/756/1/70},
url = {https://www.osti.gov/biblio/22092437}, journal = {Astrophysical Journal},
issn = {0004-637X},
number = 1,
volume = 756,
place = {United States},
year = {2012},
month = {9}
}