Seeking extraterrestrial life: Astrophysicist says habitable zones too narrow
When it comes to the search for extraterrestrial life, research focuses on the so-called habitable zone of stars. This may have been premature.
(Image: JPL/NASA)
An Israeli astrophysicist is advocating for expanding the concept of the habitable zone, which is central to the search for extraterrestrial life. The term refers to the region around a star where, according to current understanding, liquid water can exist on exoplanets. However, Amri Wandel of the Hebrew University of Jerusalem now states that this region should be expanded both towards the star and outwards. Gravitationally bound exoplanets, which always show only one side to their star, could therefore hold liquid water much closer to the star on the eternal night side. Further away, on the other hand, liquid water could still exist under massive ice shells, where it is already too cold on the surface.
Could explain unexpected findings
(Image:Â Amri Wandel)
Wandel explains that many of the newly discovered exoplanets do not fit the previous model, and the James Webb Space Telescope also finds volatile gases on exoplanets outside the habitable zone. His work could explain why these also have liquid water and thus one of the most fundamental prerequisites for the emergence of Earth-like life. A visualization of his calculations shows that the habitable zone should not be a narrow band, but a relatively wide area. In the solar system, it would extend not only from Earth to almost Mars, but even encompass Mercury and the gas giants Jupiter and Saturn. Hints of subsurface oceans have already been discovered on several of their moons.
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If the assumptions about the habitable zone and its boundaries are revised, it could lead astronomers to search for traces of extraterrestrial life in places they have previously ignored, according to Wandel. We now know of more than 6,000 planets around other stars, and almost 8,000 candidates still need to be verified. Dozens of these are considered potentially habitable, even if this is often ruled out later by further observations. Wandel is now presenting his considerations in The Astrophysical Journal, where he speaks of an “extended habitable zone.”
(mho)
