There isn’t always a rhyme or reason to the way new research papers get published. Often, and entirely by coincidence, different papers will come out all at once that look at different aspects of the same problem, and when seen from an outside perspective, they paint an even more interesting picture than each paper can tell alone. In a recent episode, we brought you news of a white dwarf star – an ember of a star like our Sun that has died – and how that white dwarf was consuming one of its former planets.

Today, in a new paper in Monthly Notices of the Royal Astronomical Society, researchers led by Jay Farihi published new research on a white dwarf star surrounded by debris that appears to be shaped by the presence of a planet — a planet that formed after the star had already died. This is a new planet, a post “the star was actively fusing and alive” planet.

Researchers looked at the white dwarf WD1054–226 found fluctuations in its light that indicate 65 evenly spaced clouds of material orbiting every 25 hours. Basically, the light acts like a chaotic dashed line is passing over it.

According to Farihi: An exciting possibility is that these bodies are kept in such an evenly-spaced orbital pattern because of the gravitational influence of a nearby major planet. Without this influence, friction and collisions would cause the structures to disperse, losing the precise regularity that is observed.  A precedent for this ‘shepherding’ is the way the gravitational pull of moons around Neptune and Saturn helps to create stable ring structures orbiting these planets.

Farihi continues: The possibility of a major planet in the habitable zone is exciting and also unexpected; we were not looking for this.  However, it is important to keep in mind that more evidence is necessary to confirm the presence of a planet.

These structures are in a part of this solar system that would have been inside the star when it was a red giant in the past. Now, this region is in the white dwarf’s habitable zone. Yes, dead stars have habitable zones. White dwarfs are the slowly cooling cores of stars, and they start out so hot that they blast light in ultraviolet. Over time, they cool, but that time is measured in billions of years, and they do have evolving habitable zones for all those billions of years.

In combination with the earlier paper, this tells a remarkable story of white dwarfs both eating planets and forming planets in a remarkable “out with the old and in with the new” kind of story. A white dwarf that isn’t consuming material is a steady star that produces a regular light and a not-too-horrible environment. That offers a new possibility for life to form someplace we just hadn’t been looking, and I now wait eagerly for a sci-fi writer to pick up this idea and run.

Science is a process, and just like the plots of so many soap operas, along the way we keep learning that what we thought was true is wrong and what is real is far more fantastical than we imagined and often.

More Information

Royal Astronomical Society press release

University College London press release

“Relentless and complex transits from a planetesimal debris disc,” J Farihi et al., 2022 February 8, Monthly Notices of the Royal Astronomical Society