Wednesday, November 28, 2012

1211.6103 (David G. Turner et al.)

The Pulsation Mode of the Cepheid Polaris    [PDF]

David G. Turner, V. V. Kovtyukh, Igor Usenko, N. Gorlova
A previously-derived photometric parallax of 10.10+-0.20 mas, d=99+-2 pc, is confirmed for Polaris by a spectroscopic parallax derived using line ratios in high dispersion spectra for the Cepheid. The resulting estimates for the mean luminosity of =-3.07+-0.01 s.e., average effective temperature of =6025+-1 K s.e., and intrinsic color of (-)o=0.56+-0.01 s.e., which match values obtained previously from the photometric parallax for a space reddening of E(B-V)=0.02+-0.01, are consistent with fundamental mode pulsation for Polaris and a first crossing of the instability strip, as also argued by its rapid rate of period increase. The systematically smaller Hipparcos parallax for Polaris appears discrepant by comparison.
View original: http://arxiv.org/abs/1211.6103

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