Atmospheric retrieval from a direct imaging spectrum

This thesis presents an atmospheric retrieval study of 2M1207b using a flux-calibrated JWST/NIRSpec IFU spectrum covering 1-5.2 μm at R = 2700. The dataset is obtained by combining observations from multiple high-resolution grating configurations and is provided in the Atmospheric Spectroscopy Table of the NASA Exoplanet Archive. Atmospheric properties are derived through a Bayesian retrieval, fitting the observed spectrum with synthetic spectra generated by a one-dimensional radiative-transfer model. The analysis identifies the main molecular absorption features and constrains key parameters, including effective temperature and surface gravity, leading to a consistent characterization of the atmosphere of 2M1207b.