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arXiv · 1806.09572

Fundamental properties of red-clump stars from long-baseline H-band interferometry

A. Gallenne·G. Pietrzyński·D. Graczyk·N. Nardetto·A. Mérand·P. Kervella·W. Gieren·S. Villanova·R. E. Mennickent·B. Pilecki
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Abstract

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.

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A. Gallenne, G. Pietrzyński, D. Graczyk, N. Nardetto, A. Mérand, P. Kervella, W. Gieren, S. Villanova, R. E. Mennickent, B. Pilecki. 2018-06-25. Fundamental properties of red-clump stars from long-baseline H-band interferometry. https://doi.org/10.1051/0004-6361%2F201833341

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