Confirmation of Asymmetric Iron Absorption in WASP-76b with HARPS

TL;DR

This study confirms asymmetric iron absorption in the exoplanet WASP-76b using HARPS data, demonstrating that chemical gradients across exoplanet surfaces can be detected with multiple transit observations, advancing understanding of exoplanet atmospheres.

Contribution

It is the first confirmation of asymmetric iron absorption in WASP-76b with archival HARPS data, showing such features can be observed with smaller telescopes and multiple transits.

Findings

Asymmetric iron absorption confirmed with HARPS data.

Detection of chemical gradients across exoplanet surfaces.

Potential for mapping condensation processes across exoplanets.

Abstract

Hot Jupiters are predicted to have hot, clear daysides and cooler, cloudy nightsides. Recently, an asymmetric signature of iron absorption has been resolved in the transmission spectrum of WASP-76b using ESPRESSO on ESO's Very large Telescope. This feature is interpreted as being due to condensation of iron on the nightside, resulting in a different absorption signature from the evening than from the morning limb of the planet. It represents the first time that a chemical gradient has been observed across the surface of a single exoplanet. In this work, we confirm the presence of the asymmetric iron feature using archival HARPS data of four transits. The detection shows that such features can also be resolved by observing multiple transits on smaller telescopes. By increasing the number of planets where these condensation features are detected, we can make chemical comparisons between exoplanets and map condensation across a range of parameters for the first time.