鉄隕石の照射年代に見られる周期性

抄録

Periodicity of the cosmic-ray exposure ages has been recognized for the ³He-deficient iron meteorites. These irons might have been thrown away from the Asteroid Belt to the orbits close to the Sun. The intervals are similar to the orbital period of the Sun (~230 My) around the center of the Galaxy. Therefore, the periodicity of the exposure ages may be caused by the periodic perturbation of the Asteroid Belt due to the extrasolar stars. The exposure ages of IAB iron meteorites also reflected the periodic perturbations of the Asteroid Belt. The detailed studies of exposure history of IAB iron meteorites may reveal the history of the perturbations.