• 천문학회지
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• 제29권spc1호
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• pp.277-278
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• 1996

In attempts to detect gravitational waves, the response of some celestial systems such as the earth[l] or binary systems[2] to such waves have been investigated. Following this line of thought, here we study the possibility of excitation of the oscillation modes of a polytropic star by gravitational radiation and calculate the relevant absorption cross sections.

• 천문학회지
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• 제28권2호
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• pp.197-208
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• 1995

Real time CCD differential photometry was performed for BT Cnc in Praesepe cluster from February to March, 1994. New 885 differential V magnitudes were obtained for thirteen nights. From the frequency analysis, we have detected two distinct pulsational frequencies of $f_1$=9.7783c/d and $f_2$=7.0153c/d. The first frequency is nearly equal to the previous result(Breger 1980), but the second one is much different. Our reanalysis of the previous data obtained by Guerrero el al.(1979) indicates that the previous result of $f_s$=5.95c/d might be uncertain; it was not detected in the power spectrum. Also it turns out that our second frequency could not be fitted to the previous data and the reanalyzed frequency($f_2$=7.8813c/d) of the previous data was poor-fitted to our data. Therefore we suggest that the second frequency which might be newly excited in the nonradial mode, has been changed over the last eighteen years.