2017MNRAS.468.3342B

The mean observed internal structure constant ({bar}k_ 2,obs_) values of 14 systems were revised using new data. Mean theoretical internal structure constant ({bar}k_ 2,theo_) values were computed for two different metallicities (Z = 0.01 and 0.02) using Claret's models. It was found that the metallicity effect on {bar}k_ 2,theo_ values is too small in comparison with observational errors to estimate {bar}k_ 2,obs_ values. A comparison between observational and theoretical {bar}k₂ values reveals that the {bar}k_ 2,obs_ values are generally smaller by up to 0.1 dex, which is, however, mostly within the observational errors of the {bar}k_ 2,obs_ values, i.e. the {bar}k_ 2,theo_ values agree well with the {bar}k_ 2,obs_ values within the observational errors. For three well-observed systems (PV Cas, HS Her and DR Vul), however, the {bar}k_ 2,theo_ values are not within the observational errors of the {bar}k_ 2,obs_ values but instead significantly larger. This means that the components of these systems, at least, are more centrally condensed in comparison with presently used models. Final result on the comparison between observational and theoretical {bar}k₂ values needs further more accurate {bar}k_ 2,obs_ values, obtainable from more accurate space observations like the Kepler mission launched in 2009 (Borucki et al. 2010).