An artist’s impression of a habitable exoplanet orbiting a pulsar. Image Credit: Institute of Astronomy, University of Cambridge
Habitable planets may exist around pulsars, according to a new study.
Scientists found that the ‘habitable zone’ around a pulsar star could be the same as the distance between Earth and the Sun, but that any habitable planet would have to be large enough and have an atmosphere a million times as thick as Earth’s.
Pulsars are neutron stars measuring about 10-30km in diameter.
They have huge magnetic fields and regularly pulse with blasts of X-rays and other energetic particles.
Calculations reveal that a planet could be in orbit around a pulsar and still host life, but the planet would have to be a ‘super-Earth’ with a mass between 1 and ten times that of Earth.
Its atmosphere would also have to be thick enough to withstand the large amounts of radiation given off by the star.
The team behind the study observed pulsar PSR B1257+12, located 2,300 lightyears away in Virgo.
In 1992, astronomer Aleksander Wolszczan discovered the first exoplanet ever observed orbiting this star.
Three planets are now known to be orbiting the pulsar.
Using the Chandra X-ray Observatory, the team behind this latest study were able to observe two super-Earth planets in orbit around PSR B1257+12, with a mass of four or five times that of Earth.
The planets orbit close enough to the pulsar to be warm.
“According to our calculations, the temperature of the planets might be suitable for the presence of liquid water on their surface,” says Alessandro Patruno of Leiden University in the Netherlands, and a co-author on the paper.
“Though, we don’t know yet if the two super-Earths have the right, extremely dense atmosphere.”
It is thought that our Milky Way contains about one billion neutron stars, of which about 200,000 are pulsars.
3,000 pulsars have been studied, but just five pulsar planets have been found.