Atmospheric composition and structure of HD209458b

TL;DR

This study re-analyzes HST/STIS spectra of HD209458b, revealing atmospheric features such as Rayleigh scattering, sodium depletion, temperature inversion, and TiO/VO molecules, enhancing understanding of exoplanet atmospheres.

Contribution

It provides a detailed re-analysis of existing spectra, identifying key atmospheric components and temperature structure of HD209458b for the first time.

Findings

Detection of H2 Rayleigh scattering.

Quantification of sodium depletion.

Identification of temperature inversion and TiO/VO molecules.

Abstract

Transiting planets like HD209458b offer a unique opportunity to scrutinize their atmospheric composition and structure. Transit spectroscopy probes the transition region between the day and night sides, called limb. We present a re-analysis of existing archived HST/STIS transmission spectra of HD209458b's atmosphere. From these observations we: Identify H2 Rayleigh scattering, derive the absolute Sodium abundance and quantify its depletion in the upper atmosphere, extract a stratospheric T-P profile with a temperature inversion and explain broad band absorptions with the presence of TiO and VO molecules in the atmosphere of this planet.