Polaris the Cepheid: Still Pulsating !

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Session 36 -- Giant and Supergiant Stars
Oral presentation, Monday, 9, 1995, 2:00pm - 3:30pm

[36.03] Polaris the Cepheid: Still Pulsating !

M. Krockenberger, R.W. Noyes, D.D. Sasselov (Harvard--Smithsonian Center for Astrophysics)

We present high resolution spectra of Polaris ($\alpha$UMi), taken with the AFOE in May and September of 1994. The quality of the data allows velocity measurements accurate to $\sim$50 m/sec . We find that Polaris is pulsating with an amplitude of $\sim$0.9 km/sec . This could mean that the pulsation amplitude of Polaris is increasing after having gone through a minimum or that the amplitude has stabilized at the measured value after having declined for this century.

We also compare the time of the velocity maximum with previous measurements to find that a significant change in phase has occurred. This could be due to a change in period or a phase jump of $\sim$$180^\circ$.

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