Extreme-ultraviolet- and X-Ray-driven Photochemistry of Gaseous Exoplanets
Journal
Date Issued
2022
Abstract
The interaction of exoplanets with their host stars causes a vast diversity in bulk and atmospheric compositions and physical and chemical conditions. Stellar radiation, especially at the shorter wavelengths, drives the chemistry in the upper atmospheric layers of close orbiting gaseous giants, providing drastic departures from equilibrium. In this study, we aim at unfolding the effects caused by photons in different spectral bands on the atmospheric chemistry. This task is particularly difficult because the characteristics of chemical evolution emerge from many feedbacks on a wide range of timescales, and because of the existing correlations among different portions of the stellar spectrum. In describing the chemistry, we have placed particular emphasis on the molecular synthesis induced by X-rays. The weak X-ray photoabsorption cross sections of the atmospheric constituents boost the gas ionization to pressures inaccessible to vacuum and extreme-ultraviolet photons. Although X-rays interact preferentially with metals, they produce a secondary electron cascade able to ionize efficiently hydrogen- and helium-bearing species, giving rise to a distinctive chemistry.
Volume
3
Issue
1
Start page
1
Issn Identifier
2632-3338
Rights
open.access
File(s)![Thumbnail Image]()
Loading...
Name
Locci_2022_Planet._Sci._J._3_1.pdf
Description
Pdf editoriale
Size
1.35 MB
Format
Adobe PDF
Checksum (MD5)
70bfd5038697659e2c1d0743eda26748