We talk a lot about planet formation around here. This is because, well, we’d like to know how we got here, and by looking at other forming solar systems we can make assumptions about how we got here and start to imagine someday answering things like how often these solar systems create life.

What we don’t talk about as much is how planets die.

This is partly because we just don’t get to see it happen very often. Planets die in a flash as they are either consumed into an expanding red giant or pulled into a stellar remnant. Catching this spark of death requires a bit of luck and knowing what it is you’re seeing when luck comes your way. Researchers from the University of Warwick studied white dwarf stars hoping for that luck as they looked for the tell-tale X-ray light from planetary debris vaporizing in the hot, dead stars’ atmosphere.

Stars like our Sun will one day stop fusing materials in their core, and when this occurs, they puff off their outer atmosphere while their core collapses down to something roughly the size of the Moon. Over time, these systems will cool, but they start out hot enough to vaporize anything that gets too close – including planets – and we see the chemical signatures of these former planets in white dwarf atmospheres.

And now, this team has seen one star, G29-38, actively consuming a former planet at a rate of more than two tons a second. As the story goes, the planet will first be torn apart by the gravity of the white dwarf, and then the former planet’s material spirals in, changing the star’s surface composition while flashing out in X-rays.

This work is published in Nature Communications with first author Tim Cunningham.

We don’t need to worry about our planet being consumed by the Sun for many billion years, but I guess it’s neat to know one possible way or world could end? Maybe?

More Information

University of Warwick press release

“A white dwarf accreting planetary material determined from X-ray observations,” Tim Cunningham et al., 2022 February 9, Nature