HD 2055

TU Cassiopeiae periods and amplitudes Light-curve observations of the double-mode Cepheid TU Cas obtained by10 different groups of observers on several photometric systems over atime span of 67 years have been carefully studied to determine thefundamental and first-overtone periods and their amplitudes on the Vmagnitude scale. The presence of a second-overtone radial pulsation isdiscussed, and it is concluded that a previous detection of this modewas spurious because of the lack of a proper zero-point correction fortwo groups of observations. It is possible that the amplitude of one ofthe two modes varies during the entire observing period, with thefundamental-mode amplitude constant at 0.69 plus or minus 0.03 and theovertone amplitude decreasing from 0.4 to 0.25 mag. If this Cepheiddisplays the two pulsation modes because it is mode switching, thisswitching time scale may be less than a few hundred years.
The light-variation and the radial-velocity curve of TU Cas explained in terms of a primary period and a beat period Not Available
Osservazioni fotografiche di stelle variabili in Cassiopea (KR, KL, IY, TU, UW, HI, GZ, HH Cassiopeiae) Not Available

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