Volume 616, August 2018
|Number of page(s)||12|
|Published online||21 August 2018|
Fundamental properties of red-clump stars from long-baseline H-band interferometry⋆
European Southern Observatory, Alonso de Córdova 3107, Casilla 19001, Santiago, Chile
2 Nicolaus Copernicus Astronomical Centre, Polish Academy of Sciences, Bartycka 18, 00-716 Warszawa, Poland
3 Universidad de Concepción, Departamento de Astronomía, Casilla 160-C, Concepción Chile
4 Millenium Institute of Astrophysics, Av. Vicuña Mackenna 4860, Santiago, Chile
5 Centrum Astronomiczne im. Mikoøaja Kopernika, PAN, Rabiańska 8, 87-100 Toruń, Poland
6 Laboratoire Lagrange, UMR7293, Université de Nice Sophia-Antipolis, CNRS, Observatoire de la Côte d'Azur, Nice, France
7 European Southern Observatory, Karl-Schwarzschild-Str. 2, 85748 Garching, Germany
8 LESIA (UMR 8109), Observatoire de Paris, PSL, CNRS, UPMC, Univ. Paris-Diderot, 5 place Jules Janssen, 92195 Meudon, France
Accepted: 9 June 2018
Observations of 48 red-clump stars were obtained in the H band with the PIONIER instrument installed at the Very Large Telescope Interferometer. Limb-darkened angular diameters were measured by fitting radial intensity profile I(r) to square visibility measurements. Half the angular diameters determined have formal errors better than 1.2%, while the overall accuracy is better than 2.7%. Average stellar atmospheric parameters (effective temperatures, metallicities and surface gravities) were determined from new spectroscopic observations and literature data and combined with precise Gaia parallaxes to derive a set of fundamental stellar properties. These intrinsic parameters were then fitted to existing isochrone models to infer masses and ages of the stars. The added value from interferometry imposes a better and independent constraint on the R −Teff plane. Our derived values are consistent with previous works, although there is a strong scatter in age between various models. This shows that atmospheric parameters, mainly metallicities and surface gravities, still suffer from a non-accurate determination, limiting constraints on input physics and parameters of stellar evolution models.
Key words: techniques: interferometric / techniques: high angular resolution / stars: late-type / stars: fundamental parameters
© ESO 2018
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