| Budget Amount *help |
¥8,320,000 (Direct Cost: ¥6,400,000、Indirect Cost: ¥1,920,000)
Fiscal Year 2020: ¥2,600,000 (Direct Cost: ¥2,000,000、Indirect Cost: ¥600,000)
Fiscal Year 2019: ¥3,120,000 (Direct Cost: ¥2,400,000、Indirect Cost: ¥720,000)
Fiscal Year 2018: ¥2,600,000 (Direct Cost: ¥2,000,000、Indirect Cost: ¥600,000)
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| Outline of Final Research Achievements |
Cometary dust particles were analyzed for oxygen and 26Al-26Mg isotopes to give constraints on accretion ages of comets and timing of dissipation of the solar nebula gas. Oxygen isotope analysis showed that the particles are all cometary in origin. Plagioclase in a cometary dust particle showed no resolvable excess of 26Mg, suggesting crystallization of the cometary plagioclase after decay of 26Al. The cometary plagioclase formed 3.9 Myr after starting of the formation of solar system based on the uncertainty of the initial 26Al/27Al ratio, which is later than that estimated in previous studies (2.6 Myr). It is considered that accretion of comets and dissipation of the solar nebula gas are later than previously though.
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