Dead Stars Might Be the Key to Finding New Worlds

The quest for life beyond Earth has always focused on stars that are shining brightly. But what if the key to finding habitable worlds lies in the remnants of stars that have already died? White dwarfs, the faint, cooling cores of stars like our Sun, might just be the answer. These stellar remnants are often overlooked in the search for life. After a star like our Sun exhausts its fuel, it sheds its outer layers, leaving behind a white dwarf. These objects are roughly the size of Earth but pack about half the Sun’s mass. There are around 10 billion of these embers in our Milky Way galaxy, and over 97 percent of all stars will end up as white dwarfs. But here’s the twist: these dim stars might still have the power to keep nearby planets warm enough for liquid water to exist. This idea challenges the old notion that life can only thrive around stars that are very much alive. It turns out that white dwarfs, despite being dead, might still have some life in them. The James Webb Space Telescope (JWST) has already spotted gas giants orbiting white dwarfs, proving that planets can survive the violent end of their star. With Webb’s infrared capabilities, astronomers can now study rocky worlds the size of Earth. This opens up new possibilities for exploring different star systems. Researchers used a climate model to compare two hypothetical ocean-covered planets with Earth-like atmospheres. One planet was placed in the habitable zone of a white dwarf, and the other around a main-sequence star similar to our Sun. The results were surprising. The planet orbiting the white dwarf was warmer and had more habitable real estate on its surface. The white dwarf planet zips around its star every 10 hours, creating powerful winds that distribute heat evenly across the planet. This rapid rotation also prevents thick, reflective clouds from forming, allowing more sunlight to reach the surface. The planet orbiting the main-sequence star, on the other hand, had more cloud cover, which reflected heat away and made it cooler. This discovery is significant because it expands the number of potential targets in the search for habitable worlds. With ten billion white dwarfs in our galaxy, even a small fraction hosting temperate rocky worlds would mean a vast number of potential homes for life. The next step is to point powerful telescopes like Webb at the brightest white dwarfs and study the atmospheres of any planets that might be orbiting them. If the models are correct, the faint glow of a dying star could one day reveal a living planet.