Professor Amri Wandel of the Hebrew University of Jerusalem has presented groundbreaking research that has the potential to change our understanding of habitable exoplanets. His latest research, published in the Astronomical Journal, highlights the importance of subglacial liquid water in expanding the traditional definition of the habitable zone.

The classic "habitable zone", often colloquially known as the "Goldilocks zone", usually refers to the area around a star where conditions allow the existence of liquid water on the surface, and by extension, life as we understand it. However, Professor Wandel's research provides a new perspective on how the presence of subglacial liquid water could significantly expand this area.

Expand the habitable zone inwards and outwards

One of the main findings of this study is the possibility of extending inward the "habitable zone" of tidally locked planets tightly surrounding M-dwarf stars, which are often considered candidates for detecting spectral evidence of life on exoplanets, so-called biosignatures. The study describes how atmospheres and liquid water could coexist on these planets, pushing the limits of the habitable zone further than previously thought.

Habitable zone boundaries under various climate and atmospheric models as a function of radiative flux received from the host star relative to the Earth. The dashed line represents the boundary proposed in this study for expansion by subglacial liquid water. Solid green lines and green shading indicate conservative habitable zone boundaries. The red curve represents the tidally locked zone (to the right of which the planet is locked). The circles represent the terrestrial planets in the solar system and several Earth-sized exoplanets orbiting M-dwarf stars. Source: AmriWandel

Additionally, the study speculates that subglacial liquid water could also expand the habitable zone beyond the outer limits of the conservative habitable zone. The findings reveal the possibility of liquid water on a more diverse set of exoplanets than previously thought, providing tantalizing opportunities in the search for extraterrestrial life.

A noteworthy implication of this study is its connection to recent observations from the James Webb Space Telescope (JWST). The possible discovery of atmospheric water vapor on the rocky Earth-sized exoplanet GJ486b and the discovery of evidence of an ocean on the super-Earth exoplanet K2-18b hint at the presence of liquid water, possibly organic chemistry, and the possibility of life on such objects. The discovery provides empirical evidence to resolve the long-standing question of whether exoplanets orbiting M-dwarf stars can maintain habitable conditions.

Professor Wandel said: "This work shows that the habitable zone of red dwarfs may be much wider than previously assumed, and that planets within the habitable zone are capable of sustaining water and atmospheres. The Webb Telescope has recently discovered water on such exoplanets, specifically in K2-18b, as predicted in the paper submitted two months ago. This latter conclusion has empirical support. In particular, it could optimize target allocation and prioritization of biosignature studies at JWST."

Professor Wandel's research sheds light on how water persists in subglacial melt layers on terrestrial planets tightly orbiting M dwarf stars, providing a unique perspective on the sustainability of liquid water. The study further explores how detecting water on various exoplanets could help determine the characteristics of their atmospheres.

Professor Amri-Wander's research highlights the transformative potential of subglacial liquid water in expanding the habitable zones of exoplanets. This discovery not only advances our understanding of habitable environments in the universe, but also illuminates the prospects for life beyond our planet.

Compiled source: ScitechDaily