Gaia FGK benchmark stars: Effective temperatures and surface gravities

By U. Heiter, Paulina Jofré, B. Gustafsson, A. Korn, C. Soubiran, F. Th'evenin. 2015

187 citations recorded by the source corpus.

Context. In the era of large Galactic stellar surveys, carefully calibrating and validating the data sets has become an important and integral part of the data analysis. Moreover, new generations of stellar atmosphere models and spectral line formation computations need to be subjected to benchmark tests to assess any progress in predicting stellar properties. Aims: We focus on cool stars and aim at establishing a sample of 34 Gaia FGK benchmark stars with a range of different metallicities. The goal was to determine the effective temperature and the surface gravity independently of spectroscopy and atmospheric models as far as possible. Most of the selected stars have been subjected to frequent spectroscopic investigations in the past, and almost all of them have previously been used as reference, calibration, or test objects. Methods: Fundamental determinations of Teff and log g were obtained in a systematic way from a compilation of angular diameter measurements and bolometric fluxes and from a homogeneous mass determination based on stellar evolution models. The derived parameters were compared to recent spectroscopic and photometric determinations and to gravity estimates based on seismic data. Results: Most of the adopted diameter measurements have formal uncertainties around 1%, which translate into uncertainties in effective temperature of 0.5%. The measurements of bolometric flux seem to be accurate to 5% or better, which contributes about 1% or less to the uncertainties in effective temperature. The comparisons of parameter determinations with the literature in general show good agreements with a few exceptions, most notably for the coolest stars and for metal-poor stars. Conclusions: The sample consists of 29 FGK-type stars and 5 M giants. Among the FGK stars, 21 have reliable parameters suitable for testing, validation, or calibration purposes. For four stars, future adjustments of the fundamental Teff are required, and for five stars the log g determination needs to be improved. Future extensions of the sample of Gaia FGK benchmark stars are required to fill gaps in parameter space, and we include a list of suggested candidates.

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/455c8f391035a9db98e862230ec51193d30a53ae

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Citations in the corpus

Stellar and substellar companions of nearby stars from Gaia DR2 (2018, background): “The secondary component 61 Cyg B is one of the 34 Gaia benchmark stars (Jofré et al. 2014; Heiter et al. 2015).”
New white dwarf and subdwarf stars in the Sloan Digital Sky Survey Data Release 12 (2015, background): “These spectra look like main sequence low metallicity A stars, but their estimated surface gravities with log gsdA > 5.5 are at least 3σ (external) larger than those of main sequence stars log gMS < 4.75 (Heiter et al. 2015).”
The PASTEL catalogue: 2016 version (2016, background): “A new feature in the 2016 version of PASTEL is to include several recent references providing effective temperatures from angular diameters and total flux at Earth for 151 stars (261 determinations by Boyajian et al. 2012a,b, 2013, 2015; von Braun et al. 2014; Heiter et al. 2015).”
The GALAH survey: observational overview and Gaia DR1 companion (2016, background): “…spectra (SNR > 95 per resolution element), as well as high-fidelity validation targets including observed benchmark stars with reliable, independent stellar parameters (Heiter et al. 2015), well studied open and globular cluster stars, and stars with confirmed asteroseismic surface gravities.”
The GALAH Survey: Second Data Release (2018, methodology): “The line list selection was originally done in conjunction with the corresponding compilation for the Gaia-ESO survey (Heiter et al. 2015a).”
Fundamental Parameters of 87 Stars from the Navy Precision Optical Interferometer (2017, methodology): “We follow Heiter et al. (2015), who established a systematic uncertainty of 5% on their FBOL determinations from a sample of 34 benchmark Gaia stars.”