  In helioseismology, there is a well-known offset between observed and
computed oscillation frequencies. This offset is known to arise from improper
modeling of the near-surface layers of the Sun, and a similar effect must occur
for models of other stars. Such an effect impedes progress in asteroseismology,
which involves comparing observed oscillation frequencies with those calculated
from theoretical models. Here, we use data for the Sun to derive an empirical
correction for the near-surface offset, which we then apply three other stars
(alpha Cen A, alpha Cen B and beta Hyi). The method appears to give good
results, in particular providing an accurate estimate of the mean density of
each star.
