May 15 – 17, 2026
College of Hakka Studies at NYCU, Zhubei, Hsinchu County 國立陽明交通大學客家學院(竹北六家校區)
Asia/Taipei timezone

Modeling Atmospheric Chemistry of the Ultra Low Density Exoplanet WASP-193b

May 16, 2026, 5:15 PM
15m
HK105

HK105

Speaker

Cheng-An Hsieh (National Taiwan University)

Description

The recently discovered exoplanet WASP-193 b represents an extreme example of a “cotton candy” gas giant exoplanet, exhibiting an exceptionally low density (⍴=0.059±0.014 g·cm^-3) that current planetary evolution models cannot explain. With a Jupiter-like radius (R_p=1.464 R_{Jup}) but a mass of only 0.139 M_{Jup}, this highly irradiated planet (T_eq=1254 K) challenges our understanding of atmospheric inflation and mass-loss mechanisms (Barkaoui et al., 2024). This population of extremely low-density planets have inflated radii that require additional heating mechanisms, such as tidal or ohmic dissipation. To investigate the physical processes driving WASP-193 b’s anomalous structure, we employ VULCAN, a comprehensive photochemical kinetics model, to simulate its thermochemical equilibrium and disequilibrium chemistry under intense stellar irradiation. The model predicts atmospheric composition and vertical thermal structure. We will apply climate and photochemical modelling to explore the observability of internal heating, assessing how internal energy flux influences molecular abundances and spectral features. Our results will constrain the role of internal heating and mass loss in producing inflated atmospheres, providing key theoretical insights into this emerging class of ultra-low-density exoplanets.

Participate the oral/poster presentation award competition Yes

Authors

Cheng-An Hsieh (National Taiwan University) Dr Shang-Min Tsai (ASIAA)

Presentation materials

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