Angular Diameters of the G Subdwarf µ Cassiopeiae A and the K Dwarfs σ Draconis and HR 511 from Interferometric Measurements with the CHARA Array
Gies, Douglas R.; Henry, Todd; Jao, Wei-Chun; Goldfinger, P. J.; Boyajian, Tabetha S.; Farrington, Chris; McAlister, Harold A.; ten Brummelaar, Theo A.; Ridgway, Stephen; Sturmann, Laszlo; Sturmann, Judit; Turner, Nils H.; Baines, Ellyn K.; Touhami, Yamina; O'Brien, David; Raghavan, Deepak
United States
Abstract
Using the longest baselines of the CHARA Array, we have measured the angular diameter of the G5 V subdwarf μ Cas A, the first such determination for a halo population star. We compare this result to new diameters for the higher metallicity K0 V stars, σ Dra and HR 511, and find that the metal-poor star, μ Cas A, has an effective temperature (Teff = 5297 +/- 32 K), radius (R = 0.791 +/- 0.008 R⊙), and absolute luminosity (L = 0.442 +/- 0.014 L⊙) comparable to those of the other two stars with later spectral types. We show that stellar models show a discrepancy in the predicted temperature and radius for μ Cas A, and we discuss these results and how they provide a key to understanding the fundamental relationships for stars with low metallicity.