Characterizing exoplanets is starting in the mid-infrared thanks to the MATISSE instrument, after the neat successes with GRAVITY. The spectrum of exoplanets allows constraining estimates of the C/O ratio, effective temperature, surface gravity, and hints about the composition of the object. However, there is still much information to uncover, as the mid-infrared is rich in interesting molecular signatures. This is why MATISSE observations are essential to better constrain the physics of these exoplanetary atmospheres. At the same time, shorter wavelengths are yet to be unveiled at higher spectral resolution and data quality.
MATISSE's spectral bands clearly reveal the importance of filling gaps in the spectral energy distribution of the planet, constraining the contributions of methane and CO in the atmosphere, as well as signatures related to clouds (such as silicates and iron), which are crucial for understanding the evolution of brown dwarfs and young giant planets. MATISSE has already demonstrated its capabilities by extracting a spectrum of $\beta$ Pic b in the L and M bands, confirming a solar C/O ratio.
Today, we can ask questions such as: for already detected exoplanets, what baseline length would be necessary for their detection, for instance, for sources discovered through radial velocities? Or, what adaptive optics system would be required to resolve the star-planet system at very short separations and large distances from Earth? We can also consider which wavelength would be most suitable based on the spectral type of the host star and the system's age to get a better contrast spectrum!