Establishing the accuracy of asteroseismic mass and radius estimates of giant stars - II. Revised stellar masses and radii for KIC 8430105

Asteroseismic scaling relations can provide high-precision measurements of mass and radius for red giant (RG) stars displaying solar-like oscillations. Their accuracy can be validated and potentially improved using independent and accurate observations of mass, radius, effective temperature and metallicity. We seek to achieve this using long period SB2 eclipsing binaries hosting oscillating RGs. We explore KIC 8430105, for which a previous study found significant asteroseismic overestimation of mass and radius when compared with eclipsing binary measurements. We measured dynamical masses and radii for both components to be significantly lower than previously established, increasing the discrepancy between asteroseismic and dynamical measurements. Our dynamical measurements of the RG component were compared to corresponding measurements of mass and radius using asteroseismic scaling relations. Uncorrected scaling relations overestimated the mass of the RG by 26 per cent, the radius by 11 per cent, and the average density by 7per cent, in agreement with studies for other systems. However, using a theoretical correction to Delta nu, we managed to obtain an asteroseismic average density that is 1 sigma consistent with our dynamical result. We obtained several measurements of nu(max) that are not fully consistent. With nu(max) = 76.78 +/- 0.81 mu Hz, the Delta nu correction provided 2 sigma consistent mass and radius for the giant. The age of the system was estimated to be 3.7 +/- 0.4 Gyr.

Automated summary

Asteroseismic scaling relations can provide high-precision measurements of mass and radius for red giant stars. This study explores the discrepancies between asteroseismic measurements and dynamical measurements in the binary system KIC 8430105. The results show that the uncorrected scaling relations overestimate the mass and radius, but a theoretical correction to Delta nu can improve the consistency between asteroseismic and dynamical measurements.