JERUSALEM, Jan. 22 (Xinhua) -- Scientists may need to widen the search for extraterrestrial life after a new study suggests liquid water could exist on planets once thought too hot or too cold.

In a statement Thursday, astrophysicist Amri Wandel of Hebrew University in Jerusalem said his research challenges the traditional concept of the "habitable zone," the narrow orbital range around a star where liquid water can survive. In our solar system, this zone lies roughly between Earth and Mars.

Published in The Astrophysical Journal, the study argues that the standard "Goldilocks" model is too limiting, especially for planets orbiting smaller, cooler stars known as M-dwarfs and K-dwarfs.

The research focuses on tidally locked planets, which keep one side facing their star and the other in permanent darkness. Using a climate model, researchers found that heat from the sunlit side could warm the dark side enough to sustain liquid water, even on worlds closer to their star than previously thought.

The findings could help explain recent observations by the James Webb Space Telescope, which detected water vapor around "super-Earths" orbiting M-dwarf stars. Previous models had deemed these planets too close to their stars for water to survive, but Wandel's work suggests they may be habitable.

The study also extends the habitable zone farther from stars. On icy, distant planets, liquid water could exist in subglacial lakes or pockets of melt beneath thick ice, similar to conditions on some moons in our solar system.

By broadening the definition of where liquid water can exist, the research gives astronomers a larger map of potential life-bearing planets and hints that the ingredients for life may be more common than previously believed.  ■