Extreme worlds? Pulsars may have habitable planets

A pulsar is not something you would like to have at home. It rotating neutron star, the collapsed remains of a massive star that ended its life with a supernova explosion. But in terms of size, it's not the biggest. They could easily fit into a larger city. But they are made from degenerate matter so they are insanely heavy. They are also surrounded by extreme gravitational and magnetic fields that make the pulsars rotate violently.

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To say that the surroundings of a pulsar are inhospitable would be an understatement. But even these crazy objects have planets. Even the first exo-planets was discovered by the PSR B1257+12 pulsar. We may not yet know whether they are the original planets, survivors of the supernova blast, or new planets from the space rubble from the supernova.

A planet near a pulsar - artists rendition - Source: NASA/JPL-Caltech/R. Hurt (SSC).

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Now the astronomers from the University of Cambridge and the University of Leiden tried to calculate the size of the habitable zone for a pulsar. Or if such a zone even exists. Their results published by the Astronomy & Astrophysics magazine are a surprise for many.

It seems that the habitable zone around a pulsar may be as big as the distance from Earth to the Sun. But it is important that the planet is a super-earth, a planet with a mass of 1 – 10 Earths. The pulsar would evaporate the atmosphere of the planet very soon if the planet was smaller.

Mihkel Kama - Source: Leiden Observatory

And does it look in the PSR B1257+12 star system? Alessandro Patruno from the University of Leiden and Mihkel Kama from the University of Cambridge discovered that two of the three exo-planets around this pulsar are super-earths and on top of that in the habitable zone. So, maybe there is some liquid water on them.