  Photometric observations from the last decade have revealed additional
low-amplitude periodicities in many classical pulsators that are likely due to
pulsations in non-radial modes. One group of multi-mode RR Lyrae stars, the
so-called 0.61 stars, is particularly interesting. In these stars, the radial
first overtone is accompanied by additional signals with period ratios around
0.61. The most promising explanation for these signals is pulsation in
non-radial modes of degrees 8 and 9. If the theory behind the additional
signals in the 0.61 stars is substantiated, it would allow us to use non-radial
modes to study classical pulsators. We aim to perform asteroseismic modeling of
selected 0.61 stars with independently determined physical parameters to test
whether this assumption behind the modeling leads to correct results. Namely,
we test whether the additional signals are indeed due to non-radial modes of
the proposed moderate degrees. We selected a number of and RR Lyrae stars that
are also 0.61 stars and have good observational constraints on their other
physical parameters. We assume that the nature of those modes is correctly
explained with non-radial modes of degrees 8 or 9. Using this assumption and
observational constraints on physical parameters, we performed asteroseismic
modeling to test whether the observed periods and period ratios can be
reproduced. For the majority of selected targets, we obtained a good match
between observed and calculated periods and period ratios. For a few targets
however, the results obtained are ambiguous and not straightforward to
interpret.
