The potassium absorption on HD189733b and HD209458b

TL;DR

This study uses high-resolution transit spectroscopy to detect and compare potassium absorption features in the atmospheres of exoplanets HD189733b and HD209458b, revealing differences in their atmospheric compositions.

Contribution

First detection of potassium excess absorption in HD189733b's atmosphere using high-resolution spectroscopy, and a comparative analysis with HD209458b to understand atmospheric differences.

Findings

Detected > 7-sigma potassium absorption in HD189733b

Set a 3-sigma upper limit for HD209458b's potassium absorption

Confirmed different atmospheric properties between the two exoplanets

Abstract

In this work, we investigate the potassium excess absorption around 7699A of the exoplanets HD189733b and HD209458b. For this purpose, we used high spectral resolution transit observations acquired with the 2 x 8.4m Large Binocular Telescope (LBT) and the Potsdam Echelle Polarimetric and Spectroscopic Instrument (PEPSI). For a bandwidth of 0.8A, we present a detection > 7-sigma with an absorption level of 0.18% for HD189733b. Applying the same analysis to HD209458b, we can set 3-sigma upper limit of 0.09%, even though we do not detect a K- excess absorption. The investigation suggests that the K- feature is less present in the atmosphere of HD209458b than in the one of HD189733b. This comparison confirms previous claims that the atmospheres of these two planets must have fundamentally different properties.