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

• Published in: Astronomy and astrophysics (Berlin) 2023-06, Vol.674, p.A58
• Main Authors: Scandariato, G., Borsa, F., Bonomo, A. S., Gaudi, B. S., Henning, Th, Ilyin, I., Johnson, M. C., Malavolta, L., Mallonn, M., Molaverdikhani, K., Nascimbeni, V., Patience, J., Pino, L., Poppenhaeger, K., Schlawin, E., Shkolnik, E. L., Sicilia, D., Sozzetti, A., Strassmeier, K. G., Veillet, C., Wang, J., Yan, F.
• Format: Article
• Language: English
• ISSN: 0004-6361; 1432-0746
• DOI: 10.1051/0004-6361/202245539

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 ≈ 7, 4, and 5, respectively, and confirm the expected systemic velocity of ≈13 km s −1 and the radial velocity semi-amplitude of MASCARA-1 b of ≈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.