Observational study of the relation between the AGB evolution and the space distribution of AGB stars

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We have investigated the evolution of asymptotic giant branch (AGB) stars on the basis of the space distribution of AGB stars. There are two kinds of AGB stars : Carbon stars and M-type stars. We suspect that the space distributions of these two-types of stars are different from each other and that the evolutionary sequence of AGB stars is not the same in the whole Galaxy. To clarify the difference or the similarity of the evolutionary sequence depending on the location in the Galaxy, it is essential to know the space distribution of carbon stars and M-type stars. To get the space distribution of carbon stars we carried out near-infrared photometric observations and estimated total radiant energies (TRE) from individual carbon stars. By comparing the TRE with assumed intrinsic luminosity, distances of carbon stars are evaluated and then we obtained the space distribution of carbon stars. The space distribution of M-type stars is obtained by analyzing the photometric data of IRAS observations. Comparing the space distributions of carbon stars and M-type stars, we have found that two distributions are different from each other. This result shows that the evolutionary sequence of AGB stars is not the same in the whole galaxy.