# High-Resolution Transit Spectroscopy of Warm Saturns

## TL;DR

This study demonstrates the use of high-resolution optical transmission spectroscopy to detect atmospheric sodium in a low-mass exoplanet, showcasing ground-based methods for characterizing atmospheres of smaller planets.

## Contribution

It extends transit spectroscopy techniques to lower-mass exoplanets, providing the first sodium detection in HAT-P-12b and constraining atmospheric compositions of two sub-Saturn planets.

## Key findings

- Likely sodium detection in HAT-P-12b's atmosphere
- Constraints on atmospheric composition of both planets
- Validation of ground-based high-resolution spectroscopy for low-mass exoplanets

## Abstract

We present high-resolution optical transmission spectroscopy of two sub-Saturn mass transiting exoplanets, HAT-P-12b and WASP-69b. With relatively low densities and high atmospheric scale heights, these planets are particularly well-suited to characterization through transit spectroscopy, and serve as ideal candidates for extending previously-tested methods to lower planetary masses. Using a single transit for each planet, we take advantage of the Doppler cross-correlation technique to search for sodium, potassium, and water absorption features. Our analysis reveals a likely ($3.2\sigma$) detection of sodium absorption features in the atmosphere of HAT-P-12b, and enables us to place constraints on the presence of alkaline and molecular species in the atmospheres of both planets. With our results, we highlight the efficacy of ground-based campaigns for characterizing exoplanetary atmospheres, and pave the way for future analyses of low-mass planets.