Retrieval of the fluid Love number $k_2$ in exoplanetary transit curves

Understand

We are witness to a great and increasing interest in internal structure, composition and evolution of exoplanets.

• However, direct measurements of exoplanetary mass and radius cannot be uniquely interpreted in terms of interior structure, justifying the need for an additional observable.
• The second degree fluid Love number, $k_2$, is proportional to the concentration of mass towards the body's center, hence providing valuable additional information about the internal structure.
• When hydrostatic equilibrium is assumed for the planetary interior, $k_2$ is a direct function of the planetary shape.