Debate over the planet occurrence rates around intermediate-mass stars has hinged on the accurate determination of masses of evolved stars , and has been exacerbated by a paucity of reliable , directly-measured fundamental properties for these stars .
We present long-baseline optical interferometry of five evolved intermediate-mass ( \sim 1.5 \mathrm { M } _ { \odot } ) planet-hosting stars using the PAVO beam combiner at the CHARA Array , which we combine with bolometric flux measurements and parallaxes to determine their radii and effective temperatures .
We measured the radii and effective temperatures of 6 Lyncis ( 5.12 \pm 0.16 \mathrm { R } _ { \odot } , 4949 \pm 58 K ) , 24 Sextantis ( 5.49 \pm 0.18 \mathrm { R } _ { \odot } , 4908 \pm 65 K ) , \kappa Coronae Borealis ( 4.77 \pm 0.07 \mathrm { R } _ { \odot } , 4870 \pm 47 K ) , HR 6817 ( 4.45 \pm 0.08 \mathrm { R } _ { \odot } , 5013 \pm 59 K ) , and HR 8641 ( 4.91 \pm 0.12 \mathrm { R } _ { \odot } , 4950 \pm 68 K ) .
We find disagreements of typically 15 per cent in angular diameter and \sim 200 K in temperature compared to interferometric measurements in the literature , yet good agreement with spectroscopic and photometric temperatures , concluding that the previous interferometric measurements may have been affected by systematic errors exceeding their formal uncertainties .
Modelling based on BaSTI isochrones using various sets of asteroseismic , spectroscopic , and interferometric constraints tends to favour slightly ( \sim 15 per cent ) lower masses than generally reported in the literature .