An updated metal-dependent theoretical scenario for Classical Cepheids. (arXiv:2206.11154v1 [astro-ph.SR])
<a href="http://arxiv.org/find/astro-ph/1/au:+Somma_G/0/1/0/all/0/1">Giulia De Somma</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Marconi_M/0/1/0/all/0/1">Marcella Marconi</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Molinaro_R/0/1/0/all/0/1">Roberto Molinaro</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Ripepi_V/0/1/0/all/0/1">Vincenzo Ripepi</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Leccia_S/0/1/0/all/0/1">Silvio Leccia</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Musella_I/0/1/0/all/0/1">Ilaria Musella</a>

To properly quantify possible residual systematic errors affecting the
Classical Cepheid distance scale, a detailed theoretical scenario is
recommended. By extending the set of nonlinear convective pulsation models
published for $Z=0.02$ citep[][]{Desomma2020a} to $Z=0.004$, $Z=0.008$ and
$Z=0.03$, we provide a detailed homogeneous nonlinear model grid taking into
account simultaneous variations of the mass-luminosity relation, the efficiency
of super-adiabatic convection and the chemical composition. The dependence of
the inferred Period-Radius, Period-Mass-Radius, and
Period-Mass-Luminosity-Temperature relations on the input parameters is
discussed for both the Fundamental and First Overtone modes. The trend of the
instability strip getting redder as the metallicity increases is confirmed for
the additional ML assumptions and mixing length values. From the obtained
multi-filter light curves, we derive mean magnitudes and colors and in turn
Period-Luminosity-Color and Period-Wesenheit relations for each assumed
chemical composition, mass-luminosity relation and efficiency of
super-adiabatic convection. Application to a well-studied sample of Cepheids in
the Large Magellanic Cloud allows us to constrain the dependence of the
inferred distance modulus on the assumed mass-luminosity relation, and the
inclusion of the metallicity term in the derivation of Period-Wesenheit
relations allows us, for each assumed mass-luminosity relation, to predict the
metallicity dependence of the Cepheid distance scale. The obtained
metal-dependent Period-Wesenheit relations are compared with recent results in
the literature and applied to a sample of Gaia Early Data Release 3 Galactic
Cepheids with known metal abundances to derive individual parallaxes. The
comparison of these predictions with Gaia results is finally discussed.

To properly quantify possible residual systematic errors affecting the
Classical Cepheid distance scale, a detailed theoretical scenario is
recommended. By extending the set of nonlinear convective pulsation models
published for $Z=0.02$ citep[][]{Desomma2020a} to $Z=0.004$, $Z=0.008$ and
$Z=0.03$, we provide a detailed homogeneous nonlinear model grid taking into
account simultaneous variations of the mass-luminosity relation, the efficiency
of super-adiabatic convection and the chemical composition. The dependence of
the inferred Period-Radius, Period-Mass-Radius, and
Period-Mass-Luminosity-Temperature relations on the input parameters is
discussed for both the Fundamental and First Overtone modes. The trend of the
instability strip getting redder as the metallicity increases is confirmed for
the additional ML assumptions and mixing length values. From the obtained
multi-filter light curves, we derive mean magnitudes and colors and in turn
Period-Luminosity-Color and Period-Wesenheit relations for each assumed
chemical composition, mass-luminosity relation and efficiency of
super-adiabatic convection. Application to a well-studied sample of Cepheids in
the Large Magellanic Cloud allows us to constrain the dependence of the
inferred distance modulus on the assumed mass-luminosity relation, and the
inclusion of the metallicity term in the derivation of Period-Wesenheit
relations allows us, for each assumed mass-luminosity relation, to predict the
metallicity dependence of the Cepheid distance scale. The obtained
metal-dependent Period-Wesenheit relations are compared with recent results in
the literature and applied to a sample of Gaia Early Data Release 3 Galactic
Cepheids with known metal abundances to derive individual parallaxes. The
comparison of these predictions with Gaia results is finally discussed.

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