The PEPSI Exoplanet Transit Survey (PETS) III. The detection of Fe I, Cr I, and Ti I in the atmosphere of MASCARA-1 b through high-resolution emission spectroscopy

Context. Hot giant planets such as MASCARA-1 b are expected to have thermally inverted atmospheres, which makes them perfect laboratories for atmospheric characterization through high-resolution spectroscopy. Nonetheless, previous attempts at detecting the atmosphere of MASCARA-1 b in transmission have led to negative results.Aims. We aim to detect the optical emission spectrum of MASCARA-1 b.Methods. We used the high-resolution spectrograph PEPSI to observe MASCARA-1 (spectral type A8) near the secondary eclipse of the planet. We cross-correlated the spectra with synthetic templates computed for several atomic and molecular species.Results. We detect Fe I, Cr I, and Ti I in the atmosphere of MASCARA-1 b with a S/N approximate to 7, 4, and 5, respectively, and confirm the expected systemic velocity of approximate to 13 km s(-1) and the radial velocity semi-amplitude of MASCARA-1 b of approximate to 200 km s(-1). The detection of Ti is of particular importance in the context of the recently proposed phenomenon of Ti cold-trapping below a certain planetary equilibrium temperature.Conclusions. We confirm the presence of an atmosphere around MASCARA-1 b through emission spectroscopy. We conclude that the atmospheric non-detection in transmission spectroscopy is due to the strong gravity of the planet and/or to the overlap between the planetary track and its Doppler shadow.

Automated summary

In this study, the optical emission spectrum of the hot giant planet MASCARA-1 b was detected through high-resolution spectroscopy. The presence of iron, chromium, and titanium elements in the planet's atmosphere was confirmed, which is significant for understanding the atmospheric characteristics of hot giant planets.