Research Interests
(1) Formation and Evolution of Protoplanetary Disks
It is considered that "star + planetary" systems like our Solar System are formed through a protoplanetary disk surrounding a central star. The main target of our group is to reveal how the disk is formed and evolved to form planets. And we are conducting following studies:
・Numerical simulations of radiative transfer and comparisons with observational data
・Numerical simulations of physical and chemical evolutions of the disk.
(2) Evolution of Dust Particles in Protoplanetary Disks
The disk mainly consists of Hydrogen and Helium gas, but it also contains about 1 wt% of solid material (water ice, silicate, and metal) in the form of small particles. These are called "dust particles." They are initially about 0.1 micron in size. They collide each other and grow to form planets that are as large as 10,000 km.
We are studying how the dust particles evolve to form planets. Especially, focusing on the phase when the dust particles are as small as 1 mm or less, we are theoretically investigating,
・thermal heating processes on the dust particles (e.g., formation of chondrules),
・evolution of planet forming material.
(3) Massive Star Formation
Star formation still remains an unsolved problem in the astronomy. In particular, formation process of massive stars, that are about 10 times of the Sun's mass or more, has not been revealed yet. In the massive star formation process, researchers think that the radiation pressure coming from the forming star should be strong and affect the process considerably. But the details of the effect is not understood at all.
We are studying the effect of radiation pressure and the formation process of the massive star using our experiences and knowledge of the radiative transfer calculations.
(4) Planetary Atmosphere
Structure and observability of planetary atmosphere are studied.
Temperature of planetary atmosphere is detemined by a balance between the heating by the central star irradiation and the cooling by the radiation from the atmosphere. The balance depends on the composition, amount, and other properties of the atmosphere, and this mechanism is studied.
Properties of exoplanet atmosphere are investigated using a light traveling in the atmosphere. We examine what kind of properties can be deciphered from these observations.