Astronomy & Astrophysics manuscript no. paper2_metalpoor c ESO 2020 June 11, 2020 Fundamental stellar parameters of benchmark stars from CHARA interferometry I. Metal-poor stars I. Karovicova1; 2, T. R. White3; 4, T. Nordlander5; 6, L. Casagrande5; 6, M. Ireland5, D. Huber7, and P. Jofré8 1 Zentrum für Astronomie der Universität Heidelberg,Landessternwarte, Königstuhl 12, 69117 Heidelberg, Germany e-mail:
[email protected] 2 Institut für Theoretische Astrophysik, Philosophenweg 12, 69120 Heidelberg, Germany 3 Sydney Institute for Astronomy (SIfA), School of Physics, University of Sydney, NSW 2006, Australia 4 Stellar Astrophysics Centre (SAC), Department of Physics and Astronomy, Aarhus University, Ny Munkegade 120, DK-8000 Aarhus C, Denmark 5 Research School of Astronomy & Astrophysics, Australian National University, Canberra, ACT 2611, Australia 6 Center of Excellence for Astrophysics in Three Dimensions (ASTRO-3D), Australia 7 Institute for Astronomy, University of Hawai‘i, 2680 Woodlawn Drive, Honolulu, HI 96822, USA 8 Universidad Diego Portales, Núcleo de Astronomía, Av. Ejército Libertador 441, Santiago, Chile Received January 28, 2020; accepted May 8, 2020 ABSTRACT Context. 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 benchmark stars is currently limited, owing to the difficulty in determining reliable effective temperatures (Teff ) in this regime. Aims. We aim to construct a new set of metal-poor benchmark stars, based on reliable interferometric effective temperature determi- nations and a homogeneous analysis. The aim is to reach a precision of 1% in Teff , as is crucial for sufficiently accurate determinations of the full set of fundamental parameters and abundances for the survey sources.