Mass, radius, and composition of the transiting planet 55 Cnc e : using interferometry and correlations --- A quick update

TL;DR

This paper updates the mass, radius, and density estimates of exoplanet 55 Cnc e using new observational data and interferometric methods, refining its internal structure and gaseous envelope characteristics.

Contribution

The study incorporates recent observations and Gaia DR2 data to improve the precision of 55 Cnc e's physical parameters and internal composition estimates.

Findings

Planet radius: 1.947 ± 0.038 R_⊕

Planet mass: 8.59 ± 0.43 M_⊕

Density precision doubled, gaseous envelope radius: 0.03 ± 0.02 R_p

Abstract

In a recent paper (Crida et al. 2018, accepted on April 19), we presented a method to derive the mass and radius of a transiting exoplanet and their intrinsic correlation, that we applied to 55 Cnc e. We wrote: "More precise observations of the transit would be very useful in this particular case and would allow to increase significantly the gain on the planetary density precision." Three months later, Bourrier et al. (2018) published new observations of the system. Additionally, Gaia's DR2 was released on April 25, 2018. The purpose of this research note is solely to implement these precise new data in our pipeline to provide an up-to-date result of our model. We find $R_p = 1.947\pm 0.038\,R_\oplus$ and $M_p = 8.59\pm 0.43\,M_\oplus$. We also double the precision on the planetary density ($\rho_p = 1.164\pm 0.062\,\rho_\oplus$), which allows us to refine the estimates for all interior parameters of interest. In particular, we now find that the radius of the gaseous envelope is $0.03\pm 0.02\,R_p$.