Precision angular diameters for 16 southern stars with VLTI/PIONIER

Abstract

In the current era of Gaia and large, high signal to noise stellar spectroscopic surveys, there is an unmet need for a reliable library of fundamentally calibrated stellar effective temperatures based on accurate stellar diameters. Here we present a set of precision diameters and temperatures for a sample of 6 dwarf, 5 sub-giant, and 5 giant stars observed with the PIONIER beam combiner at the VLTI. Science targets were observed in at least two sequences with five unique calibration stars each for accurate visibility calibration and to reduce the impact of bad calibrators. We use the standard PIONIER data reduction pipeline, but bootstrap over interferograms, in addition to employing a Monte-Carlo approach to account for correlated errors by sampling stellar parameters, limb darkening coefficients, and fluxes, as well as predicted calibrator angular diameters. The resulting diameters were then combined with bolometric fluxes derived from broadband Hipparcos-Tycho photometry and MARCS model bolometric corrections, plus parallaxes from Gaia to produce effective temperatures, physical radii, and luminosities for each star observed. Our stars have mean angular diameter and temperatures uncertainties of 0.8% and 0.9% respectively, with our sample including diameters for 10 stars with no pre-existing interferometric measurements. The remaining stars are consistent with previous measurements, with the exception of a single star which we observe here with PIONIER at both higher resolution and greater sensitivity than was achieved in earlier work.

The GALAH survey: effective temperature calibration from the InfraRed Flux Method in the Gaia system

“…Finally, we assemble a list of interferometric measurements from the recent literature: Bigot et al (2011), Boyajian et al (2012a,b), Huber et al (2012), Maestro et al (2013), White et al (2013White et al ( , 2018, Gallenne et al (2018), Baines et al (2018), Rains et al (2020), and Karovicova et al (2020). For all these stars, we adopt reddening, log (g), and [Fe/H] reported in the above papers.…”

Fundamental stellar parameters of benchmark stars from CHARA interferometry

“…Optical interferometry offers this ideal approach by allowing the precise measurement of the angular diameter, θ (e.g. Boyajian et al 2012aBoyajian et al ,b, 2013von Braun et al 2014;Ligi et al 2016;Baines et al 2018; Article number, page 1 of 14 Rabus et al 2019;Rains et al 2020). From the angular diameter, in combination with the bolometric flux, F bol , the effective temperature T eff can be determined directly as described by the Stefan-Boltzmann relation.…”

The SAPP pipeline for the determination of stellar abundances and atmospheric parameters of stars in the core program of the PLATO mission

“…The T eff values rely on interferometric angular diameters measured with CHARA and VLTI facilities and bolometric fluxes obtained either via integrating the observed spectral energy distributions (SEDs) or indirectly by converting the photometry into F bol using synthetic calibrations. δ Eri is the only star for which we give a preference to the recent accurate T eff and radius values based on the interferometric angular diameter measured with VLTI/PIONEER (Rains et al 2020). The surface gravities were determined using masses estimated from evolutionary tracks, angular diameters, and Hipparcos parallaxes, which are mostly in excellent agreement with Gaia DR2 and Gaia EDR3 values for the reference sample (see Fig.…”