Puffy Venuses: the Mass-Radius Impact of Carbon-Rich Atmospheres on Lava Worlds

• DOI: 10.48550/arxiv.2405.08998
• Publication Date: 2024-05-14
• Authors: Bo Peng; Diana Valencia
• Keywords: Earth and Planetary Astrophysics (astro-ph.EP); FOS: Physical sciences; Astrophysics - Earth and Planetary Astrophysics

The recent advancements in exoplanet observations enable the potential detection of exo-Venuses, rocky planets with carbon-rich atmospheres. How extended these atmospheres can be, given high carbon abundances, has not been studied. To answer this, we present a model for theoretical class exoplanets - puffy Venuses characterized by thick, carbon-dominated equilibrium global magma oceans. Our accounts and hydrogen partition between atmosphere ocean, as well C-H-O chemistry throughout semi-grey, radiative-convective atmosphere. We find that radius inflation Venus is significant on small irradiated planets: content 1200 ppm (or ordinary chondrites) generate an ~0.16 0.3 $R_{\oplus}$ Earth-mass planet temperatures 1500 to 2000 K. identify TOI-561 b especially promising candidate, whose under-density could be attributed thick C-rich also advocate interpretation 55 Cancri e, where JWST observation indicates presence CO/CO2 Puffy may thus constitute testable alternative interior structure underdense low-mass exoplanets.