Science Talk - What Are Pulsar Planets?

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2024-11-18 07:00:04

2022 marks the 30-year anniversary since the discovery of the first exoplanets, which happened to be orbiting a pulsar - one of the most unusual places we could find any planet. But what is a pulsar planet, and how did they get there?

Artist impression of the PSR B1257+12 system - a pulsar with three exoplanets orbiting around it. Credit: NASA/JPL-Caltech/R. Hurt.

It's been 30 years since the first exoplanet was discovered, and those first exoplanets ... well, they were found orbiting a pulsar. A planet orbiting a pulsar, you ask? YES! this is super weird and rare, so let's dive in.

Pulsars are born when a massive star (usually 8-25 times the mass of our Sun) explodes in a supernova event. These are extremely energetic events that blast most of the progenitor star apart. But just as most of the star gets flung out into space, the inner part of the star falls in on itself under the force of gravity.

This creates some rather fascinating, and equally terrifying, outcomes. Firstly, about 1.4 times the mass of the Sun is crushed down into a diameter no bigger than a regional town (~20 kilometres across), so the density is off the charts. So dense, that a teaspoon full of this material would weigh as much as all of humanity combined into a big ball of mush.