Welcom to Atsuo Okazaki's Home Page

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Hi,

Thank you for paying a visit to my home page. I'm a theoretical astrophysicist working at the Department of Architecture and Building Engineering*, Faculty of Engineering, Hokkai-Gakuen University, Sapporo, Japan.

* Sounds strange? My job has nothing to do with architecture. I teach Astronomy, an optional subject, to first-year students from all faculties (Faculties of Law, Economy, Business Administration, Humanities, and Engineering). There are no science departments nor science majors in my university.

I've been interested in the physics of accretion/decretion disks. My Ph.D. thesis (1985) was on global m=1 oscillation modes in accretion disks. I also worked on trapped oscillations in relativistic accretion disks (1987). Then, my interest moved to in the physics of Be-star decretion disks (Be stars are early type stars with equatorial disks). I studied the global m=1 oscillation modes in Be disks and the structure of viscous decretion disks around Be stars (1991-2001)

Since 1996, I've been working mainly on Be/X-ray binaries, performing numerical simulations with a Smoothed Particle Hydrodynamics (SPH) code. Be/X-ray binaires are very intereting objects consisting of a Be star and, in general, a neutron star. The orbit is wide and, mostly, eccentric. The interaction in these systems is quite complicated. The goals of my research in this field are to understand this complicated interaction, e.g., the tidal interaction of the Be disk with the neutron star, the phase-dependent mass transfer from the Be disk to the neutron star, and its effect on the accretion disk structure and evolution, and to construct a unified model for the X-ray activity of these systems, such as periodical (Type I) and occasional giand (Type II) outbursts.

In 2007, I started numerical study of colliding wind binaries. It's really interesting to see how the colliding winds interact with each other, even if the SPH method is not the best one to study problems with strong shocks.

If you have any interest in Be/X-ray binaries or colliding winds, click on the"Be/X simulations" button or the "Colliding wind simulations" button in the left frame, respectively. I hope you'll find something interesting/exciting there.