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The pulsation mode of the Cepheid Polaris
Source:
Abstract:
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 ⟨MV⟩ = −3.07 ± 0.01 s.e., average effective temperature of ⟨Teff⟩ = 6025 ± 1 K s.e., and intrinsic color of (⟨B⟩ − ⟨V⟩)0 = +0.56 ± 0.01 s.e., which match values obtained previously from the photometric parallax for a space reddening of EB−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.
Description:
Subject:
- Polestar
- Cepheids
