Research Highlights

The research areas mainly cover the following three topics, leading to the understanding of the structure formation and its feedback on various scales in the Universe:

1. Star and Planet Formation;
2. Galaxy Formation and Cosmology;
3. Energy Feedback and Interstellar Medium.

Star and Planet Formation

Our research efforts spreads from molecular cloud cores, processes of magnetized gravitational collapse, formation and evolution of protoplanetary disks, launching of magnetized centrifugal winds, star-disk interactions, jets and outflows, to evolution and dynamics of circumstellar and circumplanetary disks, disk-planet interactions, processes leading to the formation of planets, exoplanets and meteorites.

	Observational signatures of early disk formation by MHD models Exploring protostellar disk formation via misaligned rotation axes and magnetic field, and their observable features. The streamlines on the column density maps show the direction of flows along the picture ...(more)
	Kinetic signatures in disks produced by multi-Jupiter-mass planets Moment-2 image for the 13C18O J = 3–2 transition of the fiducial model at face on. The location of the circumplanetary disk is labeled. A 4×10-3 stellar mass planet induces ...(more)
	Planet migration in dusty protoplanetary disks Numerical simulation of low-mass planets migrating in dust-laden protoplanetary disks. The top panels show the perturbed gas and dust densities in the disk with initial metallicity 0.3 and particle Stokes ...(more)
	Making planetesimals in turbulent disks is not easy The "streaming instability" (SI) in a physical protoplanetary disk model. ...(more)
	Earth-sized planet formation around late M dwarfs Numerical simulations of the time evolution of orbital radii of protoplanets, i.e., their dynamical histories. The top panel is the case for protoplanets around a 1 solar mass star, and ...(more)
	Finding planets using Machine Learning A schematic diagram of the DPNNet (Disk Planet Neural Network) using a fully connected multi-layer perceptron. The first layer in yellow takes as input six feature variables observed from the ...(more)
	Meteorites as a clue to the accretion in the Solar System Comparison between the numerical estimation of the rim thickness (hatched regions) and observed thicknesses of fine-grained rims (open circles) on the rim thickness and chondrule fraction plane. The dotted line ...(more)

Galaxy Formation and Cosmology

We are aiming at clarifying the multi-scale physics regarding the cosmological structure formation: large-scale effects of dark energy, spatial structures of dark matter distribution, galaxy formation and evolution, dust and chemical enrichment in galaxies, and stellar feedback through supernova explosions. We also predict observational signatures of first galaxies to reveal the origin of galaxies.

	Hydrodynamical evolution of supernovae and its effect on galaxy evolution How First Supernovae Altered Early Star Formation? ...(more)
	Dust enrichment in a cosmic volume Cosmological simulation with dust formation and destruction ...(more)
	Dust properties predicted in a cosmological simulation We (Yu-Hsiu Huang, Hiroyuki Hirashita, et al.) modeled dust evolution in Milky Way-like galaxies by post-processing the IllustrisTNG cosmological hydrodynamical simulations in order to predict dust-to-gas ratios and grain size ...(more)
	First galaxies Gas density distribution of the first galaxy after 33 Myr of evolution calculated by Chen & Chen (in preparation). The gas and metals inside supernova remnants mixes with surrounding gas ...(more)
	Theoretical modeling of large-scale galaxy distribution for a test of cosmic acceleration The black solid line is the quadrupole moment of the galaxy power spectrum (the suppression of the power on small scales is due to virial motions of satellite galaxies) and ...(more)

Energy Feedback and Interstellar Medium

We are also aiming at revealing high-energy phenomena related to black holes and compact objects, since energy input (feedback) from these objects could affect the structure formation on various scales.

	World’s First 3D Simulations Reveal the Physics of Superluminous Supernovae The nebula phase of the magnetar-powered super-luminous supernova from our 3D simulation. At the moment, the supernova ejecta has expanded to a size similar to the solar system. Large scale ...(more)
	Lightning black holes in dense molecular clouds (A) Side view of a BH magnetosphere. Photons are emitted from infrared to soft gamma-ray energies by the hot gas falling toward the BH in the equatorial, accretion (cyan) region. ...(more)
	Evolution of grain size distribution in the interstellar medium Based on a one-zone evolution model of grain size distribution in a galaxy, we (Hirashita et al. 2020) calculated the evolution of infrared spectral energy distribution (SED), considering silicate, carbonaceous ...(more)