AM CVn 系統是屬於正在交互作用的雙白矮星系統，被分類為激變星（Cataclysmic Variable stars）的一種。它的光度變化週期大約在5到65分鐘左右。廣義相對論預測，像這樣的系統能發射重力波並且損失角動量，而這可能就是造成這個系統質量傳遞的主要原因。 我們使用鹿林天文台LOT來進行可見光的觀測，我們總共觀測了3個目標，分別是GP Com；CR Boo及HP Lib。我們的結果顯現GP Com並沒有明顯的光變週期。而這個結果和Nather, Robinson, & Stover (1981) and Marsh, Horne, & Rosen (1991)這一群人所得到的結論相符合。在CR Boo的部分，我們可以在它的光度曲線中看到大振幅的亮度變化。我們發現當它的光變從亮變暗時，顏色則由藍變紅，並且呈現吸收現象。在HP Lib的部分，我們找到1118秒及1148秒的週期。1118秒的這個週期和O’Donighue et al. (1994)這群人所找到的superhump週期是吻合的；而1148這個週期也許是由其他機制所造成的。 AM CVn stars contain two white dwarfs of extreme mass ratio in close proximity. The secondary star fills its Roche lobe and transfers material to the much more massive primary via an accretion disk. It is currently believed that they are interacting binary white dwarf systems (Faulkner, Flannery, & Warner 1972). The observed photometric periods are between 5 and 65 minutes. The theory of general relativity predicts that such a system would emit gravitational waves and loose angular momentum. This drives mass transfer from the lower-mass white dwarf to its companion. We observed unique helium Cataclysmic Variables GP Com, CR Boo, and HP Lib using 1-meter telescope of the Lulin Observatory. Our results show that GP Com doesn’t have stable photometric periodicities. This consists with those of Nather, Robinson, & Stover (1981) and Marsh, Horne, & Rosen (1991). Long-amplitude, rapid variations are clearly seen with a time scale of a few days for CR Boo. We find CR Boo becomes redder when it becomes fainter. And the state from bright to faint is due to absorption. For HP Lib, we detected two clear periods. One is consistent with the conclusions of O’Donighue et al. (1994) study. Another period of 1148 s might be caused by other mechanisms.
