  The characterization of exoplanets relies on that of their host star.
However, stellar evolution models cannot always be used to derive the mass and
radius of individual stars, because many stellar internal parameters are poorly
constrained. Here, we use the probability density functions (PDFs) of directly
measured parameters to derive the joint PDF of the stellar and planetary mass
and radius. Because combining the density and radius of the star is our most
reliable way of determining its mass, we find that the stellar (respectively
planetary) mass and radius are strongly (respectively moderately) correlated.
We then use a generalized Bayesian inference analysis to characterize the
possible interiors of 55 Cnc e. We quantify how our ability to constrain the
interior improves by accounting for correlation. The information content of the
mass-radius correlation is also compared with refractory element abundance
constraints. We provide posterior distributions for all interior parameters of
interest. Given all available data, we find that the radius of the gaseous
envelope is $0.08 \pm 0.05 R_p$. A stronger correlation between the planetary
mass and radius (potentially provided by a better estimate of the transit
depth) would significantly improve interior characterization and reduce
drastically the uncertainty on the gas envelope properties.
