Planetary Sciences Division Seminar
Title : Atmosphere Characterization of the Hot-Jupiter Exoplanets
Date : 03-07-2025
Time : 16:00:00
Speaker : Dr. Soumya Sengupta
Area : Planetary Sciences Division
Venue : ONLINE
Abstract
Hot Jupiters, tidally locked to their host stars, exhibit extreme day–night temperature contrasts that drive vigorous atmospheric circulation. In my recent work, I analytically and numerically quantified how this heat redistribution shapes their temperature–pressure (T–P) profiles and dayside emission spectra. Using discrete space theory radiative transfer simulations, I demonstrated that reduced heat redistribution leads to hotter daysides, stronger thermal inversions, and higher emission fluxes. Application to exoplanet XO-1b revealed near-complete heat redistribution, resolving key degeneracies in its atmospheric characterization. Beyond circulation, my research also addresses two crucial aspects: • Radius Inflation: Ionized atmospheric flows coupled with magnetic fields generate Ohmic dissipation within the radiative and convective zones. MESA evolutionary simulations, parameterized by atmospheric flow velocities, successfully reproduce the observed inflated radii of hot Jupiters through this internal heating mechanism. • Spectral Separation: I have generalized Chandrasekhar’s diffuse reflection theory to unify thermal emission and scattering, allowing precise separation of planetary spectra from stellar contamination in ultra-hot Jupiters. In future work, I plan to integrate equilibrium and non-equilibrium chemistry into circulation models to better capture day–night variations in chemical abundances to study the effect of atmospheric heat redistribution on the atmospheric chemistry and finally its imprints on the emission spectra. Additionally, I aim to extend these frameworks to lower-mass, potentially habitable tidally locked terrestrial planets to inform climate and habitability studies. I also plan to develop improved radiative transfer tools that can simultaneously handle complex emission, scattering, and chemical processes, providing stronger predictive power for upcoming JWST and ARIEL observations.
Title : Mineralogical Characterization of Mare Australe: A Unique Region on the Moon
Date : 04-07-2025
Time : 16:00:00
Speaker : Dr Neha Panwar
Area : Planetary Sciences Division
Venue : Seminar Room # 113/114 (Thaltej Campus)
Abstract
Mare Australe (47.77°S, 91.99°E) is a volcanic province ~1000 km in diameter at the eastern nearside and farside boundary of the Moon. It consists of 248 mapped basaltic patches arranged in a more-or-less circular pattern. Initially classified as a “distinct” basin, it was later considered a “no topographic basin” due to a lack of identifiable topographic features. The results from the GRAIL mission, did not confirm the presence of a basin coinciding with the previously proposed one. Instead, GRAIL suggested the presence of a ~880 km diameter impact structure northwards named the Australe North Basin centered at 35.5°S, 96°E. In the earlier study geological evidences were provided to further establish the presence of the Australe North Basin. Volcanic activity at Lacus Solitudinis and Bowditch Crater, once thought to be isolated, is now linked to Australe North Basin. Based on the re-defined basin boundaries in the region a significant part of Mare Australe’s basalts lie outside the boundaries of Australe North. These basaltic units of Mare Australe remain largely uncharacterized. In this seminar, I will present a detailed investigation into the mineralogical diversity of the Mare Australe region. This study aims to shed light on the nature and origin of the distinctive style of volcanism in the region, highlighting the unique geological setting of Mare Australe and its implications for lunar volcanic evolution.