LRG-BEASTS III: Ground-based transmission spectrum of the gas giant orbiting the cool dwarf WASP-80

TL;DR

This study presents ground-based transmission spectra of the hot Jupiter orbiting WASP-80, revealing a hazy atmosphere without sodium or potassium absorption, challenging previous claims of potassium detection.

Contribution

First ground-based transmission spectrum of WASP-80b using low-resolution spectroscopy, providing new insights into its atmospheric composition and haze presence.

Findings

Inconsistent with previous potassium detection

No sodium absorption observed

Spectra indicate a hazy atmosphere

Abstract

We have performed ground-based transmission spectroscopy of the hot Jupiter orbiting the cool dwarf WASP-80 using the ACAM instrument on the William Herschel Telescope (WHT) as part of the LRG-BEASTS programme. This is the third paper of a ground-based transmission spectroscopy survey of hot Jupiters using low-resolution grism spectrographs. We observed two transits of the planet and have constructed transmission spectra spanning a wavelength range of 4640-8840A. Our transmission spectrum is inconsistent with a previously claimed detection of potassium in WASP-80b's atmosphere, and is instead most consistent with a haze. We also do not see evidence for sodium absorption at a resolution of 100A.