What Elemental Ratios in Exoplanet Atmospheres Reveal About Planet Formation

by Dubey Dwaipayan (University Observatory of Ludwig-Maximilians-Universität München)

Wednesday 4 Feb 2026, 21:20 → 21:40 Asia/Shanghai

Tsung-Dao Lee Institute

Time:  21:20-21:40 (UTC+8), 4 February 2026, Wednesday
Host: Dong Lai
Location: Online
Join Tencent Meeting：https://meeting.tencent.com/dm/rXLIkv2nzsHN
Meeting ID: 192651862 (no password）

Abstract:

Understanding whether exoplanet atmospheres preserve a chemical memory of how and where planets formed in a protoplanetary disk is an important step toward connecting observed planetary systems to their origins. Because formation environments cannot be observed directly, astronomers often rely on elemental ratios, particularly the carbon-to-oxygen ratio (C/O), as chemical tracers of protoplanetary disk conditions, planetary migration, and volatile delivery. Carbon plays a significant role in this picture, yet deciphering complete carbon chemistry from atmospheric observation is especially challenging due to overlapping spectral features from multiple carbon-bearing species. In this talk, I present a chemically informed framework that links atmospheric chemistry, spectroscopic analysis, and population-level inference. I first show how global elemental budgets, rather than individual molecules, regulate which chemical signatures emerge in the spectra of hot Jupiters and sub-Neptunes, and why this naturally amplifies degeneracies in carbon-dominated regions. I then demonstrate, using a homogeneous analysis of James Webb Space Telescope and Hubble Space Telescope transmission spectra, that widely reported demographic trends in C/O arise from hidden flexibility in standard "free-chemistry" Bayesian retrieval models rather than from intrinsic planetary physics. I conclude by outlining my research vision at the Tsung-Dao Lee Institute: developing a population-level framework that connects stellar abundances, protoplanetary disk chemistry, planetary interiors, and atmospheric composition, providing a robust pathway for interpreting exoplanet populations in the James Webb Space Telescope era.

 

Biography:

I am a final-year Ph.D. candidate at the University Observatory of Ludwig-Maximilians-Universität München, where my research focuses on understanding how elemental ratios inferred from exoplanet atmospheres encode planetary formation and evolution. My work combines atmospheric chemistry, spectroscopic analysis, and Bayesian retrieval techniques applied to observations from the James Webb Space Telescope, the Hubble Space Telescope, and high-resolution ground-based facilities. I have led population-level studies that demonstrate how assumptions in atmospheric retrieval models can bias inferred chemical trends and have developed chemically informed frameworks to improve the physical interpretation of exoplanet demographics. At the Tsung-Dao Lee Institute, I aim to link stellar abundances, planetary interiors, and atmospheric composition to build a coherent picture of chemical inheritance across exoplanet populations.