WATANABE Seiichiro Nagoya Univ., Grad. School of Sci., Asso. Prof., 理学研究科, 助教授 (50230967)
WATANABE Naoki Hokkaid Univ., Inst. of Low Temp. Sci., Assistant Prof., 低温科学研究所, 助手 (50271531)
ARAKAWA Masahiko Hokkaido Univ., Inst. of Low Temp. Sci., Assistant Prof., 低温科学研究所, 助手 (10222738)
|Budget Amount *help
¥15,400,000 (Direct Cost: ¥15,400,000)
Fiscal Year 2001: ¥4,500,000 (Direct Cost: ¥4,500,000)
Fiscal Year 2000: ¥10,900,000 (Direct Cost: ¥10,900,000)
Heating and collision experiments were performed involving interstellar organic material analogue to determine the distribution of interstellar organic material in the proto solar nebula and to investigate the growth of organic grains. We found that there were interstellar organic grains in 2.1-3.0 AU, silicate grains <2.1 AU, and ice grains>3.0 AU. We also found that gas evaporated at around 2.2 AU is very reductive. The organic material in 2.1-3.0 AU is very sticky ; the sticking threshold velocity of the mm-size organic grains is 5 m/s. This shows a very rapid coagulation of organic grain aggregates, the formation of planetesimals even the early stage of the turbulent accretion disk. The planetesimals in this region become achondrites' parent bodies. In contrast, the formation of planetesimals in <2.1 AU and >3.0 AU occur when passive disk is formed, because silicate and ice grains are not sticky. The planetesimals in <2.1 AU and >3.0 AU become ordinary and carbonaceous chondrites' parent bodies, respectively. In these framework, we discuss a redox state of chondrites, an oxygen isotope composition of meteorites and planets, and the formation of chondrules. We have succeded to give an explanation for various sequences among meteorites and planets by the heliocentric distance only : the sequence from the sun is the Earth, Mars, LL, L, H, E, Aubrite, HED, Acapulcoite, Ureilite, CO, CV, CM, CI.