Volume 563, March 2014
|Number of page(s)||6|
|Section||Stellar structure and evolution|
|Published online||06 March 2014|
Revisiting the fundamental properties of the Cepheid Polaris using detailed stellar evolution models
Department of Physics & AstronomyEast Tennessee State
Received: 22 January 2014
Accepted: 6 February 2014
Polaris the Cepheid has been observed for centuries, presenting surprises and changing our view of Cepheids and stellar astrophysics, in general. Specifically, understanding Polaris helps anchor the Cepheid Leavitt law, but the distance must be measured precisely. The recent debate regarding the distance to Polaris has raised questions about its role in calibrating the Leavitt law and even its evolutionary status. In this work, I present new stellar evolution models of Cepheids to compare with previously measured CNO abundances, period change and angular diameter. Based on the comparison, I show that Polaris cannot be evolving along the first crossing of the Cepheid instability strip and cannot have evolved from a rapidly-rotating main sequence star. As such, Polaris must also be at least 118 pc away and pulsates in the first overtone, disagreeing with the recent results of Turner et al. (2013, ApJ, 762, L8).
Key words: stars: distances / stars: fundamental parameters / stars: evolution / stars: mass-loss / stars: individual: Polaris / stars: variables: Cepheids
© ESO, 2014
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