The Araucaria project: High-precision orbital parallax and masses of eclipsing binaries from infrared interferometry^⋆

¹ European Southern Observatory, Alonso de Córdova 3107, Casilla 19001 Santiago, Chile
e-mail: agallenn@eso.org, alexandre.gallenne@gmail.com
² Laboratoire Lagrange, UMR7293, Université de Nice Sophia-Antipolis, CNRS, Observatoire de la Côte dAzur, Nice, France
³ Nicolaus Copernicus Astronomical Centre, Polish Academy of Sciences, Bartycka 18, 00-716 Warszawa, Poland
⁴ Universidad de Concepción, Departamento de Astronomía, Casilla 160-C, Concepción, Chile
⁵ Millenium Institute of Astrophysics, Av. Vicuña Mackenna 4860, Santiago, Chile
⁶ Centrum Astronomiczne im. Mikołaja Kopernika, PAN, Rabiańska 8, 87-100 Toruń, Poland
⁷ Leibniz-Institut für Astrophysik Potsdam (AIP), An der Sternwarte 16, 14482 Potsdam, Germany
⁸ Instituut voor Sterrenkunde, KU Leuven, Celestijnenlaan 200D, 3001 Leuven, Belgium
⁹ LESIA, Observatoire de Paris, Université PSL, CNRS, Sorbonne Université, Univ. Paris Diderot, Sorbonne Paris Cité, 5 place Jules Janssen, 92195 Meudon, France
¹⁰ European Southern Observatory, Karl-Schwarzschild-Str. 2, 85748 Garching, Germany

Received: 3 May 2019
Accepted: 8 October 2019

Abstract

Context. The precise determinations of stellar mass at ≲1% provide important constraints on stellar evolution models. Accurate parallax measurements can also serve as independent benchmarks for the next Gaia data release.

Aims. We measured the masses and distance of binary systems with a precision level better than 1% using a fully geometrical and empirical method.

Methods. We obtained the first interferometric observations for the eclipsing systems AI Phe, AL Dor, KW Hya, NN Del, ψ Cen and V4090 Sgr with the VLTI/PIONIER combiner, which we combined with radial velocity measurements to derive their three-dimensional orbit, masses, and distance.

Results. We determined very precise stellar masses for all systems, ranging in precision from 0.04% to 3.3%. We combined these measurements with the stellar effective temperature and linear radius to fit stellar isochrones models and determined the age of the systems. We also derived the distance to the systems with a precision level of 0.4%.

Conclusions. The comparison of theoretical models with stellar parameters shows that stellar models are still deficient in simultaneously fitting the stellar parameters (T_eff, R and M) with this level of precision on individual masses. This stresses the importance of precisely measuring the stellar parameters to better calibrate stellar evolution models. The precision of our model-independent orbital parallaxes varies from 24 μas as to 70 μas and the parallaxes provide a unique opportunity to verify whether the future Gaia measurements have systematic errors.