November 22, 2023 – Subglacial water, a pivotal element for broadening the boundaries of habitable zones on exoplanets, may be more widespread than previously believed, according to Hebrew University of Jerusalem (HU) researchers ─ a finding that could support the prospect of life beyond our planet.  

In a new study, published in the Astronomical Journal, Prof. Amri Wandel of the Racah Institute of Physics at Hebrew University has discovered that the presence of subglacial liquid water can extend considerably beyond the Habitable Zone.  

Often referred to as the “Goldilocks Zone,” the classic Habitable Zone defines the region around a star that has conditions amenable to the presence of surface liquid water and life.  

“This work demonstrates that the Habitable Zone of red dwarfs, the most common [type of] stars in the Milky Way, is likely to be significantly broader than assumed and that planets within the zone have the capacity to maintain water and an atmosphere,” said Prof Wandel. “The latter conclusion is empirically supported by recent findings of water on these exoplanets by the James Webb Space Telescope, which could help optimize target allocations and priorities for biosignature research.” 

The observations made by the James Webb Space Telescope (JWST) corroborate the significant implications of this research. The potential identification of atmospheric water vapor on GJ 486 b, a rocky Earth-sized exoplanet, and the evidence of an ocean on K2-18b, a Super Earth exoplanet, hint at the existence of liquid water and the potential for life on such celestial bodies. This discovery provides empirical substantiation to address the long-standing question of whether exoplanets orbiting M-dwarf stars can sustain habitable conditions. 

Prof. Wandel’s research elucidates how water on terrestrial planets closely orbiting M-dwarf stars may persist within a subglacial melting layer, which presents a unique perspective on the sustainability of liquid water. The study further explores how the detection of water on various exoplanets can aid in constraining their atmospheric characteristics. 

This research spotlights the transformative potential of subglacial liquid water for expanding the Habitable Zone of exoplanets. Prof. Wandel’s discovery not only advances our comprehension of habitable environments in the cosmos, but it also calls for further research into the possibility of life beyond Earth.