September 22, 2025
ESO Headquarters
Europe/Berlin timezone

Is the high-energy environment of K2-18b special?

Sep 22, 2025, 4:00 PM
15m
Eridanus Auditorium (ESO Headquarters)

Eridanus Auditorium

ESO Headquarters

Karl-Schwarzschild-Straße 2 85748 Garching bei München

Speaker

Surangkhana Rukdee (MPE)

Description

The high-energy environments of host stars can shape the chemistry of exoplanet atmospheres. In nearby benchmark systems, hosting rocky to sub-Neptunian planets, we focus on the impact on biosignature gases such as oxygen, methane, and carbon dioxide. With new data from Chandra, eROSITA and XMM-Newton, we study the X-ray flux variability on timescales of days to years. Using a Bayesian framework to model multi-temperature coronal plasmas and integrating it with the VPLanet and KOMPOT modeling packages, we examine how XUV-driven escape affects atmospheric composition and thermal structure. K2-18b's atmosphere benefits from an exceptionally low level of XUV irradiation. Looking forward, we discuss our observational strategy aimed at characterizing sub-Neptune exoplanet host stars and detecting atmospheric biosignatures.

Category Exoplanet detections and characterization
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