The PEPSI exoplanet transit survey (PETS) I: Investigating the presence of a silicate atmosphere on the super-earth 55 Cnc e

The study of exoplanets and especially their atmospheres can reveal key insights on their evolution by identifying specific atmospheric species. For such atmospheric investigations, highresolution transmission spectroscopy has shown great success, especially for Jupitertype planets. Towards the atmospheric characterization of smaller planets, the superEarth exoplanet 55 Cnc e is one of the most promising terrestrial exoplanets studied to date. Here, we present a highresolution spectroscopic transit observation of this planet, acquired with the PEPSI instrument at the Large Binocular Telescope. Assuming the presence of Earthlike crust species on the surface of 55 Cnc e, from which a possible silicatevapor atmosphere could have originated, we search in its transmission spectrum for absorption of various atomic and ionized species such as Fe , Fe +, Ca , Ca +, Mg and K , among others. Not finding absorption for any of the investigated species, we are able to set absorption limits with a median value of 1.9 × RP. In conclusion, we do not find evidence of a widely extended silicate envelope on this superEarth reaching several planetary radii.

2D maps of the residual spectra at different orbital phases in the velocity range for strong opacity bearing species i.e. Mg I (top), H beta, and K I (center) and Ca II (bottom). The color bar shows the residual Flux in %. The dashed black line shows the expected absorption trace.

Read more: Keles et al. 2022, MNRAS, 513, 1544