The obliquity and atmosphere of the hot Jupiter WASP-122b (KELT-14b) with ESPRESSO: An aligned orbit and no sign of atomic or molecular absorption

TL;DR

This study used high-resolution ESPRESSO spectrograph data to analyze the orbit and atmospheric composition of hot Jupiter WASP-122b, finding an aligned orbit and no detectable atomic or molecular absorption features.

Contribution

First high-resolution spectroscopic analysis of WASP-122b with ESPRESSO, measuring a nearly aligned orbit and searching for atmospheric species without detection.

Findings

Orbit is well-aligned with the stellar equator.

No evidence of atomic or molecular species in the atmosphere.

Possible masking effects or absence of species explain non-detections.

Abstract

Thanks to their short orbital periods and hot extended atmospheres, hot Jupiters are ideal candidates for atmosphere studies with high-resolution spectroscopy. New stable spectrographs help improve our understanding of the evolution and composition of those types of planets. By analyzing two nights of observations using the ESPRESSO high-resolution spectrograph, we studied the architecture and atmosphere of hot Jupiter WASP-122b (KELT-14b). By analyzing the Rossiter-McLaughlin (RM) effect, we measured the spin-orbit angle of the system to be lambda = 0.09 +0.88/-0.90 deg. This result is in line with literature obliquity measurements of planetary systems around stars with effective temperatures cooler than 6500 K. Using the transmission spectroscopy, we studied the atmosphere of the planet. Applying both the single-line analysis and the cross-correlation method, we looked for Ca I, Cr I, FeH, Fe I, Fe II, H2O, Li I, Mg I, Na I, Ti I, TiO, V I, VO, and Y I. Our results show no evidence of any of these species in WASP-122b's atmosphere. The lack of significant detections can be explained by either the RM effect covering the regions where the atmospheric signal is expected and masking it, along with the low signal-to-noise ratio (S/N) of the observations or the absence of the relevant species in its atmosphere.