Contributions > By speaker > Godoy Barraza Nicolas Ignacio

κAndb is a planetary-mass companion orbiting a B9IV star at a wide separation of ~50–100 au. Its age, mass, and atmospheric properties have been debated for over a decade due to differences in atmospheric models and inhomogeneous datasets. To address this, we obtained new JWST/MIRI coronagraphic observations in 3 mid-infrared filters—F1065C, F1140C, and F1550C—complemented by a homogeneous recalibration of all existing NIR data using a modern ATLAS stellar model. Our analysis reveals that κAndb is best described by cloudy atmosphere models, consistent with its L0/L2 spectral type and silicate-dominated features suggested by MIRI color-magnitude diagrams. From atmospheric modeling, we derive a Teff of 1791±68 K, a radius of 1.42±0.06 Rj, and log(g) = 4.35±0.07 dex, significantly improving previous constraints. Using evolutionary and atmospheric models, we derive a mass of 17.3±1.8 MJup and age of 47±7 Myr, supporting κAndb's membership in the Columba association and its position at the planet/brown dwarf boundary.