AAS 204th Meeting, June 2004
Session 6 Stars: Winkin' and Blinkin'
Poster, Monday, May 31, 2004, 9:20am-6:30pm, Ballroom

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[6.10] Overlooked Properties of the Cepheid Polaris

D. G. Turner (Saint Mary's University)

The North Star, Polaris, and the anonymous, poorly populated, previously-unnoticed, star cluster in which it lies, have been target objects in a newly initiated campaign of photometric observation using the Burke-Gaffney Observatory at Saint Mary’s University. Polaris continues to pulsate with its familiar 4-day period, albeit at a very low level; its 2003 amplitude in V was 0.024, typical of recent observations. The star also exhibits a rapid rate of period change that has probably been underestimated by previous investigators. The declining light amplitude and rapid rate of evolution through the Cepheid instability strip raise questions about its evolutionary status and pulsation mode. The possibility is raised that Polaris is crossing the instability strip for the first time, and that its declining light amplitude is linked to a relatively narrow width of the instability strip for first crossers. Cluster main sequence fitting provides an estimate for its luminosity of MV = -3.37 ±0.07, which differs from the value inferred from its Hipparcos parallax. The Cepheid may be an overtone pulsator.

The author(s) of this abstract have provided an email address for comments about the abstract: turner@ap.smu.ca

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