Nuclei of half-destroyed planets from stars detectable by radio telescopes

There are stars that, after burning all their “fuel,” turn into so-called “white dwarfs” but project their outer layers outward before performing this transformation. This material, projected at very high speed, destroys nearby objects and also strongly damages the planets by removing the outer layers of the latter in addition to the atmospheres.

According to a study by researchers at the University of Warwick, published in Monthly Notices of the Royal Astronomical Society, the remaining nuclei of these planets can “survive” for a necessary time, from 100 million to a billion years, so that they can be detected by our telescopes.

This is not an absolute novelty: already in the early 90s, Alexander Wolszczan of Pennsylvania State University discovered one of these planets around a pulsar using a method to detect radio waves emitted by the star.

Researchers at the University of Warwick intend to improve this method to detect the magnetic field that forms between a white dwarf and a planetary nucleus in orbit around it. The magnetic field can, in fact, form a unipolar inductor circuit in which the remaining nucleus of the planet acts as a conductor thanks to the fact that inside the nucleus there are more than anything metallic compounds.

This is a real circuit whose radiations are emitted as radio waves that can be detected by terrestrial radio telescopes. Among other things, an effect of this kind has already been noted between Jupiter and one of his moons, Io.

According to Dimitri Veras, one of the authors of the study, “There is a weak point to detect these planetary nuclei: a nucleus too close to the white dwarf would be destroyed by tidal forces and a nucleus too far away would not be detectable. Also, if the magnetic field is too strong, it would push the core into the white dwarf, destroying it. Therefore, we should only look for planets around the white dwarf ones with weaker magnetic fields at a distance of about 3 solar rays, the distance Mercury-Sun.”

In any case, finding the only nucleus of a “naked” planet would represent a very important discovery that would help to discover the history of star systems as well as allowing you to take a look at the future history of our solar system and specifically of our planet which should not be very different.

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