Simulation of the H$\alpha$ absorption for the hot Jupiter HAT-P-32 b

The paper presents the results of modeling the absorption spectrum in the H$\alpha$ and He 10830 Å lines for the hot Jupiter HAT-P-32 b. The simulation was carried out using a 3D hydrodynamic model coupled to a Monte Carlo model of Ly$\alpha$ photon transfer. It was determined that to explain the absorption in both lines at a ratio ${\rm H}/{\rm He}=99/1$, high values of the XUV flux and stellar Ly$\alpha$ flux are required: $F_{\rm XUV}=100$ erg cm$^{-2}$ s$^{-1}$ and $I_{\rm Ly\alpha}=600$ erg cm$^{-2}$ s$^{-1}$, which may indicate high activity of the star. New parameters were also found that describe the absorption at ${\rm H}/{\rm He}=97/3$ while requiring less extreme $F_{\rm XUV}=25$ erg cm$^{-2}$ s$^{-1}$ and $I_{\rm Ly\alpha}=600$ erg cm$^{-2}$ s$^{-1}$. Monte Carlo modeling showed that the absorption in the H$\alpha$ line is formed by stellar photons producing H(2) concentrations at a level of $10^2$–$10^3$ cm$^{-3}$ in the atmospheric layer up to $2R_{\rm p}$, where the absorption occurs.