White dwarfs could host life-supporting planets

Does a star have to be alive – that is, shining from within, burning thermonuclear fuel at its core – in order to sustain life? Scientists assumed that white dwarfs – the dense remnants of dead stars – would likely be unable to support life on nearby planets. They assumed these continuously cooling stellar corpses would be unable to provide a consistent source of energy. But on March 18, 2025, researchers at the Florida Institute of Technology said they’d investigated whether white dwarfs could power three processes that have helped life to thrive on Earth. And they found these dead stars could provide the perfect conditions for life on an Earth-like planet for nearly 7 billion years.

They published their peer-reviewed results in The Astrophysical Journal Letters on December 12, 2024.

White dwarfs are fading star cores

White dwarfs are the final evolutionary stage for most low-to-moderate-mass stars, including our sun. In fact, some 97% of stars in our Milky Way galaxy are destined to become white dwarfs. When one of these stars eventually starts to run out of hydrogen fuel, it will expand into a bloated red giant before shedding its outer layers altogether. This will produce a beautiful planetary nebula, with the star’s roughly Earth-sized core at its center. This remnant is what we call a white dwarf.

The expansion into a red giant would in many cases destroy the planets surrounding it. This is likely (although not certainly) what will happen to Earth in some 5 billion years. But studies have found that this fate is far from inevitable. And, sure enough, scientists in recent years have made various detections of planets orbiting white dwarfs.

The bigger obstacle to life orbiting a white dwarf is that these dead stars lack the fuel to perform nuclear fusion. So, although white dwarfs start their lives incredibly hot, over billions of years they leak out their trapped heat. This steady cooling is why scientists have long thought that white dwarfs are unlikely to host habitable planets. The dead stars seem unable to provide the consistent energy life would need to establish itself.

Measuring habitable zones

But a white dwarf’s heat dissipates over a timescale of billions of years. So the researchers set out to establish how long life on a nearby planet could be sustained before the white dwarf cooled too much.

They constructed a model to simulate how long a planet could remain within a white dwarf’s gradually shrinking “habitable zone”. The habitable zone is the region in which the temperature is just right for a planet to sustain liquid water on its surface. And they found that, if positioned perfectly, an Earth-like planet close to a white dwarf could receive enough starlight to maintain liquid water for 7 billion years. Considering Earth is around 4.5 billion years old and began hosting life at least 3.5 billion years ago, 7 billion years would seem more than enough time for life to emerge.

It’s worth noting that, in recent years, scientists have come to realize that the concept of habitable zones might be outdated. We now believe moons like Enceladus and Europa, far beyond our solar system’s Goldilocks zone, have global liquid oceans hidden beneath vast sheets of ice. And these oceans may well be habitable, or even inhabited. But this study focused on the only environment we know to have produced life: a planet like Earth, with abundant liquid water on its surface.

Can a white dwarf support life’s key processes?

To get a better understanding of this theoretical planet’s true habitability, the researchers also investigated whether the white dwarf’s energy would be enough to sustain two chemical processes that have helped life thrive on Earth.

The first is photosynthesis, which not only powers much of Earth’s life, but has also made our planet’s biosphere more habitable. And the second is UV-induced abiogenesis, or the generation of life from non-living matter via ultraviolet radiation. The transformation of simple molecules into more complex ones through ultraviolet radiation is seen as a likely origin of life on Earth.

And the researchers found that an ideally placed planet would receive the energy to support photosynthesis and UV-induced abiogenesis for the entirety of its 7-billion-year habitable period. And that, according to study lead Caldon Whyte, is highly rare. He explained:

That isn’t really common around most stars. Something like [our] sun, of course, can provide enough energy, but brown dwarfs and red dwarfs smaller than the sun don’t really provide the energy in [both] the UV and the photosynthesis range.

Far from being unsuited to sustaining alien life, it appears white dwarfs are uniquely suited to the task.

So are white dwarfs the key to future alien searches?

This surprising availability of energy makes planets orbiting close to white dwarfs strong candidates in the search for alien life. This is especially true given the 7 billion years of potential habitability they offer. Such an extended timeframe, the paper points out, raises the possibility of technologically advanced life. So a planet orbiting close to a white dwarf star could be a prime location to search for technosignatures.

The major complication is that we haven’t yet found a planet orbiting close enough to a white dwarf for this level of habitability. The paper acknowledges that a star’s red giant phase would likely engulf a planet in this orbital region. However, that doesn’t mean they don’t exist. Studies have suggested that planets could form again in this zone after the red giant phase, made from the recycled material of destroyed planets.

Our current generation of telescopes struggles to spot small exoplanets very close to their stars, so it’s hard to say how common this kind of planet is. But if Earth-like planets close to white dwarfs are common, they could be some of the most likely locations to find alien life.

Bottom line: According to a surprising new study, white dwarfs could provide enough energy to sustain life on a nearby Earth-like planet for some 7 billion years.

Source: Potential for Life to Exist and be Detected on Earth-like Planets Orbiting White Dwarfs

Via Florida Institute of Technology

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