Goodbye to Polaris the Cepheid
1993
New radial velocities and uvby photometry for Polaris are presented. These reveal that the pulsational amplitude of Polaris had declined to 0.59±0.19 km s −1 and 0.010±0.002 mag in V by 1992. Comparison with earlier determinations reveals an exponential change with time rather than any sudden onset of the decline, and suggests that Polaris had an amplitude near 0.12 mag (6.0 km s −1 ) prior to 1900. There is no sign of the amplitude changing in a manner consistent with a beat phenomenon; instead, the star seems destined to stop pulsating in 1994. Our data add new points to the O-C diagram of Polaris and show a continuation of the period increase known previously. We point out that departures of this diagram from a true parabola do not necessarily imply that factors other than stellar evolution are at work
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