New observational data on the internal structure constants of main-sequence stars

The mean observed internal structure constant ((k) over bar (2), (obs)) values of 14 systems were revised using new data. Mean theoretical internal structure constant ((k) over bar (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 (k) over bar (2, theo) values is too small in comparison with observational errors to estimate (k) over bar (2, obs) values. A comparison between observational and theoretical (k) over bar (2) values reveals that the (k) over bar (2, obs) values are generally smaller by up to 0.1 dex, which is, however, mostly within the observational errors of the (k) over bar (2, obs) values, i.e. the (k) over bar (2, theo) values agree well with the (k) over bar (2, obs) values within the observational errors. For three well-observed systems (PV Cas, HS Her and DR Vul), however, the (k) over bar (2, theo) values are not within the observational errors of the (k) over bar (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 (k) over bar (2) values needs further more accurate (k) over bar (2, obs) values, obtainable from more accurate space observations like the Kepler mission launched in 2009 (Borucki et al. 2010).