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تسجيل مستخدم جديدFundamental stellar parameters of benchmark stars from CHARA interferometry -- II. Dwarf stars
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Stellar models applied to large stellar surveys of the Milky Way need to be properly tested against a sample of stars with highly reliable fundamental stellar parameters. We have established a program aiming to deliver such a sample. We present new fundamental stellar parameters of nine dwarfs that will be used as benchmarks for large stellar surveys. One of these stars is the solar-twin 18Sco, which is one of the Gaia-ESO benchmarks. The goal is to reach a precision of 1% in Teff. This precision is important for accurate determinations of the full set of fundamental parameters and abundances of stars observed by the surveys. We observed HD131156 (xiBoo), HD146233 (18Sco), HD152391, HD173701, HD185395 (thetaCyg), HD186408 (16CygA), HD186427 (16CygB), HD190360 and HD207978 (15Peg) using the high angular resolution optical interferometric instrument PAVO/CHARA. We derived limb-darkening corrections from 3D model atmospheres and determined Teff directly from the Stefan-Boltzmann relation, with an iterative procedure to interpolate over tables of bolometric corrections. Surface gravities were estimated from comparisons to Dartmouth stellar evolution model tracks. We collected spectroscopic observations from the ELODIE spectrograph and estimated metallicities ([Fe/H]) from a 1D non-local thermodynamic equilibrium (NLTE) abundance analyses of unblended lines of neutral and singly ionized iron. For eight of the nine stars, we measure the Teff less than 1%, and for one star better than 2%. We determined the median uncertainties in logg and Fe/H as 0.015dex and 0.05dex, respectively. This study presents updated fundamental stellar parameters of nine dwarfs that can be used as a new set of benchmarks. All parameters were based on consistently combining interferometric observations, 3D limb-darkening modelling and spectroscopic analysis. The next paper will extend our sample to metal-rich giants.
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Benchmark stars are crucial as validating standards for current as well as future large stellar surveys of the Milky Way. However, the number of suitable metal-poor benchmarks is currently limited. We aim to construct a new set of metal-poor benchmar
ks, based on reliable interferometric effective temperature ($T_text{eff}$) determinations and a homogeneous analysis with a desired precision of $1%$ in $T_text{eff}$. We observed ten late-type metal-poor dwarf and giants: HD2665, HD6755, HD6833, HD103095, HD122563, HD127243, HD140283, HD175305, HD221170, and HD224930. Only three of the ten stars (HD103095, HD122563, and HD140283) have previously been used as benchmarks. For the observations, we used the high angular resolution optical interferometric instrument PAVO at the CHARA array. We modelled angular diameters using 3D limb darkening models and determined $T_text{eff}$ directly from the Stefan-Boltzmann relation, with an iterative procedure to interpolate over tables of bolometric corrections. Surface gravities ($log(g)$) were estimated from comparisons to Dartmouth stellar evolution model tracks. We collected spectroscopic observations from the ELODIE and FIES spectrographs and estimated metallicities ($mathrm{[Fe/H]}$) from a 1D non-LTE abundance analysis of unblended lines of neutral and singly ionized iron. We inferred $T_text{eff}$ to better than $1%$ for five of the stars (HD103095, HD122563, HD127243, HD140283, and HD224930). The $T_text{eff}$ of the other five stars are reliable to between $2-3%$; the higher uncertainty on the $T_text{eff}$ for those stars is mainly due to their having a larger uncertainty in the bolometric fluxes. We also determined $log(g)$ and $mathrm{[Fe/H]}$ with median uncertainties of $0.03,mathrm{dex}$ and $0.09,mathrm{dex}$, respectively. These ten stars can, therefore, be adopted as a new, reliable set of metal-poor benchmarks.
We present results of a long-baseline interferometry campaign using the PAVO beam combiner at the CHARA Array to measure the angular sizes of five main-sequence stars, one subgiant and four red giant stars for which solar-like oscillations have been
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Large stellar surveys of the Milky Way require validation with reference to a set of benchmark stars whose fundamental properties are well-determined. For metal-poor benchmark stars, disagreement between spectroscopic and interferometric effective te
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We present measurements of fundamental astrophysical properties of nearby, low-mass, K- and M-dwarfs from our DISCOS survey (DIameterS of COol Stars). The principal goal of our study is the determination of linear radii and effective temperatures for
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