Four stars in the central region of 47 Tuc were observed spectroscopically using IPCS. The observed result showed that two asymptotic giant branch stars have the excess of nitrogen compared with the red giant branch stars, which indicates that the radial colour gradient in a globular clursters, at least for 47 Tuc, comes from the abundance gradient among the giant stars.

ABSTRACT
Ⅰ. INTRODUCTION
Ⅱ. OBSERVATION AND REDUCTION
Ⅲ. DISCUSSION
Ⅳ. CONCLUSION
ACKNOWLEDGEMENTS

• M. S. Chun(Department of Astronomy and Meteorology, Yonsei University)