We have collected times of minimum light available in the literature for WZ Andromedae and analyzed the nature of the period variations. The O-C diagram of WZ And clearly shows that two abrupt changes near JD 2418000 and JD 2435000 are deduced by dp/p= + 4.24 |timesa 10 − 6 and dp/p= − 2.46 × 10 − 6 , respectively. For these period changes, we have introduced the equations which represent mass exchange in the close binery systems given by Biermann and Hall (1973), and the computation yieleled a mass flow of 7.42 × 10 − 5 M . from the hotter component to the cooler one. Due to the amount of mass flow, the period decrease may also be calculated. The theoritical new period after JD 2435000 became 0.69565858 days, which is in good agreement with the value 0.69566034 days found in the O-C diagram. In this computation, the mass ratio of WZ And suggested that the hotter star is the filling its Rochclooe, and thus WZ And is in Paczynski's stage II.

ABSTRACT
Ⅰ. 서론
Ⅱ. 식심시각의 수집 및 O-C곡선
Ⅲ. 질량 교환
Ⅳ. 토의와 결론
감사의 글
참고문헌
국문 요약

• 오규동(전남대학교 사범대학) | KYU-DONG OH (Department of Earth Science, College of Education, Chonnam National University)