The VMC survey - XXIII. Model fitting of light and radial velocity
  curves of Small Magellanic Cloud classical Cepheids
  We present the results of the chi2 minimization model fitting technique
applied to optical and near-infrared photometric and radial velocity data for a
sample of 9 fundamental and 3 first overtone classical Cepheids in the Small
Magellanic Cloud (SMC). The near- infrared photometry (JK filters) was obtained
by the European Southern Observatory (ESO) public survey "VISTA near-infrared
Y; J;Ks survey of the Magellanic Clouds system"(VMC). For each pulsator
isoperiodic model sequences have been computed by adopting a nonlinear
convective hydrodynamical code in order to reproduce the multi- filter light
and (when available) radial velocity curve amplitudes and morphological
details. The inferred individual distances provide an intrinsic mean value for
the SMC distance modulus of 19.01 mag and a standard deviation of 0.08 mag, in
agreement with the literature. Moreover the instrinsic masses and luminosities
of the best fitting model show that all these pulsators are brighter than the
canonical evolutionary Mass- Luminosity relation (MLR), suggesting a
significant efficiency of core overshooting and/or mass loss. Assuming that the
inferred deviation from the canonical MLR is only due to mass loss, we derive
the expected distribution of percentage mass loss as a function of both the
pulsation period and of the canonical stellar mass. Finally, a good agreement
is found between the predicted mean radii and current Period-Radius (PR)
relations in the SMC available in the literature. The results of this
investigation support the predictive capabilities of the adopted theoretical
scenario and pave the way to the application to other extensive databases at
various chemical compositions, including the VMC Large Magellanic Cloud
pulsators and Galactic Cepheids with Gaia parallaxes.
