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Minoru Sekiya Last modified date:2017.09.04

Professor / Material Science of Solar Planets
Department of Earth and Planetary Sciences
Faculty of Sciences


Graduate School
Undergraduate School
Administration Post
Other


Academic Degree
Doctor of Science
Field of Specialization
Formation and Evolution of Planetary Systems
Outline Activities
Research
(1) Formation of planetesimals
There are two conflicting theories of the formation of the planetesimals: (a) the gravitational instability of the dust layer; (b) mutual sticking of dust aggregates by non-gravitational forces. Recently, we have shown that the planetesimal formation by dust sticking is prohibited by the flow around the body (Sekiya and Takeda, 2003). Formerly, it is believed that the shear instability in the dust layer prohibits the formation of the planetesimals by the gravitational instability. Recently, we have shown that the tidal force of the sun has the effect to suppress the shear instability (Ishitsu and Sekiya, 2003). Thus the planetesimals could be formed through the gravitational instability of the dust layer.
(2) Temperature distribution of small bodies in the solar system. 
Iterative method for determining the temperature distribution of a small body in the solar system is developed and the equations of the orbital evolution due to the Yarkovsky effect are derived (Sekiya, Shimoda and Wakiya 2012; Sekiya and Shimoda 2013; Sekiya and Shimoda 2014).
(3) Chondrule Formation
Chondrites contain chondrules, i.e. mm-sized silicate spheres. The nebular shock wave is considered to be one of the most probable theories of the formation of the chondrules. Recently, we obtained the solution of the flow in the chondrule precursor melt sphere after the passage of the nebular shock wave (Sekiya, Uesugi and Nakamoto, 2003; Uesugi, Sekiya and Nalkamoto).

Education (2008)
Doctoral course students: 1
Master course students: 4
Under graduate student: 3
Lectures and exercises for students of the graduate, undergraduate and general education schools

Social activities
(1) Extension class
(2) Lectures for high school students
Research
Research Interests
  • Temeprature distribution in small bodies of the solar system
    keyword : Solar System, Asteroid, Meteorite
    2009.04Formation of planetesimals.
  • Formation of Planetesimals
    keyword : Solar System, Planets, Dust
    1994.04Formation of planetesimals.
  • Formation of chondrules
    keyword : Meteorites, Solar System, Planets, Asteroids
    1994.04Formation of chondrules.
Current and Past Project
  • Formation of the solar system inccluding the extra-terestrial materials and the origin of the life
Academic Activities
Papers
1. Minoru Sekiya, Akihito Shimoda, An iterative method for obtaining a nonlinear solution for the temperature distribution of a rotating spherical body revolving in an eccentric orbit, Planetary and Space Science, 97, 2014.07.
2. Minoru Sekiya, Akihito Shimoda, An iterative method for obtaining a nonlinear solution for the temperature distribution of a rotating spherical body revolving in a circular orbit around a star, Planetary and Space Science, 84, 112-121, 2013.08.
3. Minoru Sekiya, Akihito A. Shimoda, Shigeru Wakita, An iterative method for obtaining a nonlinear solution for the temperature distribution of a spinning spherical body irradiated by a central star, Planetary and Space Science, 60, 304-313, 2012.01.
4. Shigeru Wakita and Minoru Sekiya, Numerical simulation of the gravitational instability in the dust layer of a protoplanetary disk using a thin disk model, The Astrophysical Journal, 675巻1559-1575ページ, 2008.03.
5. Minoru Sekiya and Hidenori Takeda, Does the gas flow through a porous dust aggregate help its growth in a protoplanetary disk?, Icarus, 176, 1, 176巻 220-223ページ, 2005.01.
6. Naoki Ishitsu and Minoru Sekiya, The effects of the tidal force on shear instabilities in the dust layer of the solar nebula, Icarus, 165, 1, Vol. 165, No. 1, PP. 181-194., 2003.09.
7. Minoru Sekiya, Masayuki Uesugi and Taishi Nakamoto, Flow in a Liquid Sphere Moving with a Hypersonic Velocity in a Rarefied Gas - An Analytic Solution of Linearized Equations -, Progress of Theoretical Physics, 109, 5, Vol. 109, No. 5, PP. 717-728, 2003.05.
8. Minoru Sekiya and Hidenori Takeda, Were planetesimals formed by dust accretion in the solar nebula?, Earth, Planets and Space, 55, 5, Vol. 55, No. 5, PP. 263-269., 2003.05.
9. Minoru Sekiya, Quasi-equilibrium density distributions of small dust aggregations in the solar nebula, Icarus, 133, 2, Vol.133, No.2, PP.298-309., 1998.06.
Educational
Social
Professional and Outreach Activities
(1) Extension class(6, OCT, 2002)
(2) Lectures for high school students(28, AUG, 2003; 11, DEC, 2003).