Chemical Evolution of Spiral Galaxy

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概要

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• The time variation and the spatial variation of the gas density and the metal abundance Z on the disk of spiral galaxy are investigated by introducing the density wave theory. It becomes clear that stars are formed in the region r≲12.5 kpc mainly through the gas compression by the galactic shocks which take place with the passage of density wave, and only through the inelastic collision of clouds in r≳12.5 kpc, r being the distance from the galactic center. At the time t≳4×10^9 yr after the birth of the galaxy, the gas distribution has a maximum at the radius of about a half of the galactic radius. The efficiency of star formation from collapsing clouds is determined to be about 5 to 8%, scarcely depending upon the various conditions. Heavy elements smoothly distribute throughout the galactic disk with the decreasing abundance with r, holding almost constant ratios Z(3 kpc)/Z(10 kpc) ∽3.5 and Z(3 kpc)/Z(18 kpc)∽17 from t=0 to 15×10^9 yr. This steep distribution of metals is not consistent with observations and indicates that the gas mixing and the migration of stars have effectively occurred on the disk, whose effects are not taken into account here.

• 理論物理学刊行会の論文
• 1975-04-25

著者

• OHNISHI Tetsuya

  Department of Physics, University of Tokyo

• Ohnishi Teruaki

  Institute Of Atomic Energy Kyoto University

• Ohnisi Teruaki

  Institute Of Atomic Energy Kyoto University

関連論文

• A Model for the ^3He(d^^→, p)^4He Reation at Intermediate Energies
• Synthesis of Very Heavy Elements in Supermassive Stars
• Possible Existence of Another Polymer, Poly-C_2H_2, in Interstellar Space
• Nucleosynthesis of Superheavy Elements in the Universe
• Nuclear Synthetic Processes in Supernova Inner Shells
• Chemical Evolution of Spiral Galaxy

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