Investigating satellite formation around ice giants

2022 Fiscal Year Final Research Report

• Project/Area Number: 19K14787
• Research Category: Grant-in-Aid for Early-Career Scientists
• Allocation Type: Multi-year Fund
• Review Section: Basic Section 17010:Space and planetary sciences-related
• Research Institution: National Institute of Technology(KOSEN), Oshima College (2020-2022); University of Occupational and Environmental Health, Japan (2019)
• Principal Investigator: Suetsugu Ryo 大島商船高等専門学校, 一般科目, 准教授 (40737334)
• Project Period (FY): 2019-04-01 – 2023-03-31
• Keywords: 惑星 / 衛星 / 小天体

Outline of Final Research Achievements

1. We studied capture of planetesimals by gas drag from an atmosphere of a growing ice-giant planet. We found that some of the captured planetesimals can survive in the atmosphere for a long period of time under weak gas drag. Our results suggest that some of the present irregular satellites of ice-giant planets would have been captured by gas drag.
2. We studied the global distribution of ancient tectonic troughs, furrows on Jupiter’s satellite Ganymede. We found that furrows used to be a global-scale multi-ring structure. If it is impact origin, 150-km radius impactor is plausible.
3. We studied planetary-mass dependence of delivery of gas and dust particles onto circumplanetary disk of a growing giant planet. We found that the ratio of the mass accretion rate onto the circumplanetary disk and that into the Hill sphere is about 0.4 regardless of the planetary mass.

Free Research Field

惑星物理学

Academic Significance and Societal Importance of the Research Achievements

本研究では、天王星や海王星などの氷惑星の衛星形成過程を調べたが、系外惑星の質量は地球から氷惑星の間に分布しているものが多いことが知られている。そのため本研究から、太陽系外衛星をもちうる惑星の候補に対して制約を与えられることが期待される。
木星の衛星ガニメデは欧州宇宙機関（ESA）が推進し日本も参加する木星氷衛星探査計画（JUICE計画）の探査目標である。そのため、本研究の結果がこの探査により検証でき，木星の衛星系の形成と進化の解明が進むと期待される。