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Fundamental propert...
Fundamental properties of the Population II fiducial stars HD 122563 and Gmb 1830 from CHARA interferometric observations
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Creevey, O. L. (author)
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Thevenin, F. (author)
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Boyajian, T. S. (author)
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Kervella, P. (author)
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Chiavassa, A. (author)
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Bigot, L. (author)
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Merand, A. (author)
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- Heiter, Ulrike (author)
- Uppsala universitet,Observationell astrofysik
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Morel, P. (author)
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Pichon, B. (author)
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Mc Alister, H. A. (author)
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ten Brummelaar, T. A. (author)
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Collet, R. (author)
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van Belle, G. T. (author)
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du Foresto, V. Coude (author)
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Farrington, C. (author)
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Goldfinger, P. J. (author)
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Sturmann, J. (author)
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Sturmann, L. (author)
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Turner, N. (author)
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(creator_code:org_t)
- 2012-08-29
- 2012
- English.
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In: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 545, s. A17-
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Abstract
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- We have determined the angular diameters of two metal-poor stars, HD 122563 and Gmb 1830, using CHARA and Palomar Testbed Interferometer observations. For the giant star HD 122563, we derive an angular diameter theta(3D) = 0.940 +/- 0.011 milliarcseconds (mas) using limb-darkening from 3D convection simulations and for the dwarf star Gmb 1830 (HD 103095) we obtain a 1D limb-darkened angular diameter theta(1D) = 0.679 +/- 0.007 mas. Coupling the angular diameters with photometry yields effective temperatures with precisions better than 55 K (T-eff = 4598 +/- 41 K and 4818 +/- 54 K - for the giant and the dwarf star, respectively). Including their distances results in very well-determined luminosities and radii (L = 230 +/- 7 L-circle dot, R = 24.1 +/- 1.1 R-circle dot and L = 0.213 +/- 0.002 L-circle dot, R = 0.665 +/- 0.014 R-circle dot, respectively). We used the CESAM2k stellar structure and evolution code in order to produce models that fit the observational data. We found values of the mixing-length parameter alpha (which describes 1D convection) that depend on the mass of the star. The masses were determined from the models with precisions of < 3% and with the well-measured radii excellent constraints on the surface gravity are obtained (log g = 1.60 +/- 0.04, 4.59 +/- 0.02 dex, respectively). The very small errors on both log g and T-eff provide stringent constraints for spectroscopic analyses given the sensitivity of abundances to both of these values. The precise determination of T-eff for the two stars brings into question the photometric scales for metal-poor stars.
Keyword
- stars: fundamental parameters
- stars: individual: HD 122563
- stars: low-mass
- stars: Population II
- Galaxy: halo
- stars: individual: HD 103095
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- ref (subject category)
- art (subject category)
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- By the author/editor
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Creevey, O. L.
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Thevenin, F.
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Boyajian, T. S.
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Kervella, P.
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Chiavassa, A.
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Bigot, L.
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show more...
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Merand, A.
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Heiter, Ulrike
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Morel, P.
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Pichon, B.
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Mc Alister, H. A ...
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ten Brummelaar, ...
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Collet, R.
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van Belle, G. T.
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du Foresto, V. C ...
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Farrington, C.
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Goldfinger, P. J ...
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Sturmann, J.
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Sturmann, L.
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Turner, N.
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show less...
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Astronomy and As ...
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Uppsala University