Research Topics

Gas flow around a protoplanet  (Kurokawa and Tanigawa 2018 MNRAS)

We conduct hydrodynamic simulations of gas flow in a protoplanetary disk, the stage where planets are born. By performing high spatial resolution simulations on a supercomputer, we investigate how disk gas accretes onto a protoplanet and how the gas flow affects accretion of solid particles (dust) and planetesimals, which are the building blocks for planets. Based on the results of these simulations, we aim to elucidate the origins of planetary systems, especially how Earth-size planets and gas giants such as Jupiter formed and how various planetary systems are born.

We perform theoretical calculations (orbital dynamics calculations) of planet formation by the accretion of dust, pebbles, and planetesimals onto protoplanets. In particular, we investigate the size and rotation properties of planets formed in protoplanetary disk gas using a new research method that combines high-resolution hydrodynamic simulations and orbital calculations of solid materials. We are also proposing a new observational method to indirectly investigate the existence of such growing planets by studying the effects of small planets that cannot be directly observed on the structure of protoplanetary disks.

Trajectories of pebbles around a protoplanet (Kuwahara et al. 2022 A&A)

A scenario for the formation and evolution of asteroids (Kurokawa et al. 2022 AGU Adv.)

We analyze observational data of asteroids obtained by spacecraft remote sensing and telescope observations. We compare such data with simulations of radiative transport in regolith whose mineral assemblage is predicted by simulations of water-rock reactions and water circulation that occur inside asteroids. By combining theory and observations, we investigate where and how these asteroids as well as parent bodies of meteorites formed. The goal of this research is to elucidate the history of the solar system, especially where water and building blocks of life on Earth come from. As an extension of this research, we are also collaborating with experimental studies to simulate the chemical evolution of organic compaunds (such as amino acids) inside asteroids.

Volatile element (source of atmosphere and oceans) compositions of Earth and other terrestrial planets are determined by supply, loss, and partitioning and cycling within those planets. We have developed a theoretical model that covers these processes and are investigating the dependence of the resulting volatile compositions on planet formation and evolution scenarios. By comparing these theoretical predictions withactual planets, we aim to elucidate the factors that determine atmospheric and water contents of Earth and of other terrestrial planets.

Theoretical model for Earth's accretion  (Sakuraba et al. 2021 Sci. Rep.)

We investigate the effects of planetary atmospheric motion on the circulation and distribution of water (water vapor) and other materials. In a recent study, we examined whether water runoff from the Martian subsurface can be detected by atmospheric observations based on fluid dynamic simulations of the Martian atmosphere. By collaborating with experimental studies of groundwater runoff, we are investigating the evolution of the Martian aqueous environment and the availability of water resources for future manned exploration.

Simulationg global atmospheric circulation and water transport on Mars (*Kurokawa, *Kuroda et al. 2022 Icarus; *equal contribution)