| Abstract : | Starting from the seminal discovery of 51 Pegasi b, the discovery of more than five thousand exoplanets today has revealed a much larger chemical and physical diversity than found in the Solar System. Observational surveys like Kepler have revealed potentially habitable planets to be common, and facilities like the James Webb Space Telescope (JWST) have the ability to characterize their atmospheres in search of signs of life. Hence, one of the primary goals of exoplanetary science is to confirm the presence of an atmosphere, characterize it and measure its composition. Until today, we have been able to understand the presence of an atmosphere for only one rocky exoplanet known as 55 Cancri e, which lacks an H2-dominated atmosphere. In this talk, I will discuss atmospheric physics and chemistry of nitrogen-dominated ultra-short period super-Earth 55 Cancri e based on observations that favor a high mean molecular mass atmosphere. I will present the results from our state-of-the-art forward model of exoplanet atmospheres which couples the radiative-convective equilibrium model with photo-chemical kinetics. I will discuss how our model helps to constrain atmospheric physics (e.g., temperature-pressure profiles) and atmospheric chemistry (e.g., chemical abundances) that satisfy past space-based observations from HST.
I will also show the simulated transmission and emission spectra of the atmospheres of 55 Cancri e by varying the initial elemental C/O, N/O ratios, and the vertical mixing parameter and study the potential observability of the simulated spectra with JWST. Our work also suggests possibilities of atmospheric characterization of rocky exoplanets using Indian ground-based facilities such as the TANSPEC instrument onboard the 3.6 m ARIES Devasthal Optical Telescope (DOT) or the proposed Indian space mission EXOWORLD. |
