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Masa-aki Hashimoto Last modified date:2018.06.22

Professor / Fundamental particle physics
Department of Physics
Faculty of Sciences


Graduate School
Undergraduate School


E-Mail
Homepage
http://astrog.phys.kyushu-u.ac.jp/index.php/
We have been carried out researches, education, and public relations in some fields of Astrophysics/Astronomy. Detailed activities in these fields have been written concretely in this home page. .
Phone
092-802-4047
Fax
092-802-4047
Academic Degree
Doctor of Science
Country of degree conferring institution (Overseas)
No
Field of Specialization
Astrophysics
ORCID(Open Researcher and Contributor ID)
https://orcid.org/0000-0001-9579-0460
Total Priod of education and research career in the foreign country
03years00months
Research
Research Interests
  • Astrophysics
    keyword : Origin of elements, Big bang theory/evolution of the Universe, Structure of the compact stars, Stellar evolution, simulations of superova explosions and nucleosynthesis, netron star cooling
    1978.04Stellar evolution, supernovae explosion, nucleosynthesis,structure of neutron stars, and X-ray bursts, structure of rotating star, big bang model..
Current and Past Project
  • Unified explanation of supernova explosion mechanisum and gamma-ray burst engine
Academic Activities
Papers
1. Hashimoto, M, Effects of triple-$\alpha$ and $^{12}$C($\alpha$,$\gamma$)$^{16}$O reaction rates on the supernova nucleosynthesis in a massive star of 25$M_{\odot}$ , Progress of Theoretical and Experimental Physics, 10.1093/ptep/ptv072, 063E01, 1-16, 2015.06, We combine the reaction rates to examine the rate dependence, where the rates are considered to cover the possible variation of the rates based on experiments on the earth and theories. We adopt four combinations of the reaction rates from two triple-$\alpha$ reaction rates and two $^{12}\rm C(\alpha,\gamma)^{16}O$ ones. First, we examine the evolution of massive stars of 20 and 25 $M_{\odot}$ whose helium cores correspond to helium stars of 6 and 8 $M_{\odot}$,
respectively. While the 25 $M_{\odot}$ stars evolve to the presupernova stages for all combinations of
the reaction rates, evolutionary paths of the 20 $M_{\odot}$ stars proceed significantly different way for some combinations, which are unacceptable for progenitors of supernovae.
Second, we perform calculations of supernova explosions within the limitation of spherical symmetry and
compare the calculated abundance ratios with the solar system abundances. We can deduce some constraints to the reaction rates.
As the results, a conventional rate is adequate for a triple-$\alpha$ reaction rate and a rather higher value of the %astrophysical $s-factor$ at 300 kev, $s(300)\sim 230~\rm kev{\cdot}b$,
reaction rate within the upper limit for the experimental uncertainties
is favorable for a $^{12}\rm C(\alpha,\gamma)^{16}O$ rate. .
2. 橋本 正章, Numerical Experiments for Nuclear Flashes toward Superbursts in and Accreting Neutron Star, Journal of Astrophysics, http://dx.doi.org/10.1155/2014/817986, 2014, 1-12, 2014.10.
3. Masa-aki Hashimoto, Tsuneo Noda, Cooling of Compact Stars with Color Superconducting Phase in Quark Hadron Mixed Phase, The Astrophysical Journal, 10.1088/0004-637X/765/1/1, 765, 1, 1-5, 2013.05, Qooling processes for the supernova remnant Cas A has been investigated with use of quark star model..
4. E.P.B.A.Thushari,R.Nakamura,M.Hashimoto ,
Brans-Dicke model constrained from the Big Bang Nucleosynthesis and Magnitude Redshift, 521, A52, 1, 2010.10.
5. M. Saruwatari, M. Hashimoto,
Effects of a New Triple-α Reaction Rate on the Helium Ignition of Accreting White Dwarfs, Progress of physics, 124, 5, 925, 2010.05.
6. Masaomi Ono, Masa-aki Hashimoto, Shin-ichiro Fujimoto, Kei Kotake and Shoichi Yamada, Explosive Nucleosynthesis in Magnetohydrodynamical Jets from Collapsars, Progress of Theoretical Physics, 122, 3, 755-777, 2009.09.
7. N. Yasutake, K. Kotake, M. Hashimoto and S. Yamada, Effects of QCD phase transition on the gravitational radiation from the magneto-rotational core
collapse of massive stars, Physical Review D, 75, 084012 1-12, 2007.05.
8. T. Yoshida, M. Hashimoto, Numerical Analyses of Isotopic Ratios of Presolar Grains from Supernovae, The Astrophysical Journal, 10.1086/382942, 606, 1, 592-604, 606,1,592-604, 2004.01.
9. R. Matsuba, K. Arai, S. Fujimoto, M. Hashimoto, Nucleosynthesis inside an Accretion Disk in a Type II Collapsar, Publication of Astronomical Society of Japan, 56, 2, 407-414, 56, 407-414, 2004.01.
10. O. Koike, M. Hashimoto, R. Kuromizu, S. Fujimoto, Final Products of the Rp-process on Accreting Neutron Stars, The Astrophysical Journal, 10.1086/381354, 603, 1, 242-251, 603,1,242-251, 2004.03.