Abstract: The search for life elsewhere is one of the major frontiers of modern science. Numerous efforts are underway to detect habitable exoplanets orbiting nearby stars and to characterise their atmospheres using current and upcoming large telescopes, including the James Webb Space Telescope (JWST). The detection of atmospheric signatures of habitable Earth-like exoplanets is challenging due to their small planet-star size contrast and thin atmospheres with high mean molecular weight. A new class of habitable exoplanets, called Hycean worlds, promises to expand and accelerate the search for planetary habitability and life elsewhere. Hycean planets are expected to be temperate ocean-covered worlds with H2-rich atmospheres. Their large sizes and extended atmospheres, compared to rocky planets of similar mass, make Hycean worlds significantly more accessible to atmospheric spectroscopy. Several candidate Hycean worlds have been identified orbiting nearby M dwarf stars, making them highly conducive for transmission spectroscopy with JWST. Recently, the first JWST spectra have been reported for several Hycean candidates, leading to detections of multiple carbon-bearing molecules in their atmospheres, with important implications for their atmospheric, interior and surface conditions. These results are opening a promising new avenue in the search for life elsewhere. We will discuss recent observational and theoretical developments in the exploration of habitable exoplanets, including candidate Hycean worlds, as well as future prospects in the search for habitability and life beyond the solar system.

Bio: Nikku Madhusudhan is a Professor of Astrophysics and Exoplanetary Science at the Institute of Astronomy at the University of Cambridge. His research interests include understanding the atmospheres, interiors, formation conditions and habitability of exoplanets. He is widely known for pioneering atmospheric retrieval methods for exoplanets along with various theoretical and observational developments in the field. Most recently, his work led to a new class of habitable exoplanets, called Hycean worlds, and to the first detections of carbon-bearing molecules in candidate Hycean worlds with JWST. He obtained his PhD at the Massachusetts Institute of Technology (MIT), followed by postdoctoral positions at MIT, Princeton University, and Yale University, in the USA, before joining the faculty at the University of Cambridge in 2013, where he has remained since.