AAS 205th Meeting, 9-13 January 2005
Session 54 Pulsating Stars: RR Lyraes, Miras, Cepheids, etc.
Poster, Tuesday, January 11, 2005, 9:20am-6:30pm, Exhibit Hall

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[54.13] Polaris with New Precision

N. R. Evans (SAO), D. Buzasi (US Air Force Academy), D. Sasselov (Harvard), H. Preston (US Air Force Academy)

We have observed Polaris with the Wide-Field Infrared Explorer (WIRE) star camera. We present a light curve with a typical uncertainty of approximately 0.0001 mag in the binned data. There are two surprises in the observations of this low amplitude (approximately 0.02 mag) overtone Cepheid pulsator. First, the amplitude of variation decreases and then increases during a month of observation. This may be the analog to the Blazhko effect in RR Lyr stars, but is virtually unknown in classical Cepheids. Second, we can put a tight upper limit on the amplitude of any frequencies other than the first overtone. Near the period of Polaris (4 days) a resonance has been identified in the Fourier parameters of the light curves of other first overtone pulsators which is thought to result from excitation of the first and fourth overtone. However, we find no sign of the fourth overtone in the light curve. Comparisons with pulsation behavior in other stars and also implications will be discussed. Financial assistance has been provided by Chandra X-ray Center NASA Contract NAS8-039073 (to NRE) and NASA grant NAG5-9318 (to DB and HP).

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