Building Magrathea

Worlds that orbit two white dwarfs could be relatively common

- Lewis Dartnell

In Douglas Adams's popular sci-fi series The Hitchhiker's Guide to the Galaxy, the wandering characters find their way to a mysterious world named Magrathea that was once at the centre of the custom planet-building industry. In the story, Magrathea is described as an ancient planet orbiting around twin suns in the heart of the Horsehead Nebula. But how common might such planets actually be in our Galaxy?

Gabriele Columba, a PhD student in the department of physics and astronomy at the University of Padua, Italy, and his colleagues have been investigating. The type of planetary system they're interested in is an exoplanet orbiting a binary pair where both partners are white dwarfs - which they dub Magrathea worlds. (Although, here they're considering gas giants rather than the sort of terrestrial planet that features in Hitchhiker's.)