Upper limits on atmospheric abundances of KELT-11b and WASP-69b from a retrieval approach

TL;DR

This study uses high-resolution spectroscopy and retrieval methods to place upper limits on atmospheric molecular abundances and cloud properties of the hot Jupiters KELT-11b and WASP-69b, with tentative water detection for KELT-11b.

Contribution

It applies a retrieval approach combined with injection-recovery techniques to constrain atmospheric compositions and cloud pressures, demonstrating consistency with cross-correlation results.

Findings

Tentative H₂O detection for KELT-11b.

No significant detection of H₂S or CH₄ for either planet.

Constraints on atmospheric abundances and cloud deck pressures from non-detections.

Abstract

WASP-69b and KELT-11b are two low-density hot Jupiters, which are expected to show strong atmospheric features in their transmission spectra. Such features offer valuable insights into the chemical composition, thermal structure, and cloud properties of exoplanet atmospheres. High-resolution spectroscopic observations can be used to study the line-forming regions in exoplanet atmospheres and potentially detect signals despite the presence of clouds. We aimed to detect various molecular species and constrain the chemical abundances and cloud deck pressures using high-resolution spectroscopy. We observed multiple transits of these planets with CARMENES and applied the cross-correlation method to detect atmospheric signatures. Further, we used an injection-recovery approach and retrievals to place constraints on the atmospheric properties. We detected a tentative H$_2$O signal for KELT-11b but not for WASP-69b, and searches for other molecules such as H$_2$S and CH$_4$ resulted in non-detections for both planets. By investigating the signal strength of injected synthetic models, we constrained which atmospheric abundances and cloud deck pressures are consistent with our cross-correlation results. In addition, we show that a retrieval-based approach leads to similar constraints of these parameters.