Dead planets are not at all dead. They orbit the dead stars and give off some ghostly radio wave emissions that can be detected by scientists from Earth. This allows scientists to track planets that have been considered dead even after billions of years when their stars have run out of fuel.
The astronomers from the University of Warwick were the ones who suggested that people "tune in" to the radio waves given off by the exoplanets through their cores. They are the ones that orbit around the white dwarfs. A core is created when a planet orbits a star that has burnt out all its fuel and strips away the outer layers that serve as its covering. It leaves behind a chunk of rock that could survive for a long time.
These cores can easily be spotted. Scientists only need to look for a magnetic field between the white dwarf and the core. It comes with metallic elements, so it best acts as a conductor. Together with the core and the white dwarf, the combination creates a circuit. The radiation created from the circuit is emitted into space in the form of radio waves. These then are the waves that can be detected on Earth.
"There is always beauty in detecting the radio waves signals from these planetary cores: A Core too close to the white dwarf would be easily destroyed by tidal force, and the core that would be too far away just won't get detected," said Dr. Dimitri Veras, lead author of the study. "Also, if the magnetic field is too strong, it would push the core towards the white dwarf, which could eventually lead to its destruction. Hence, planets with a weaker magnetic fields at a separation between 3 solar radii and the Mercury-Sun distance."
There has always been that wonder how long the core could survive the outer space. The modelling that scientists have made shows that a core could live for as long as 100 years, and maybe even longer.
The team behind this new study aims to test their theory through the use of radio telescopes like the Green Bank Telescope in West Virginia or the Arecibo in Puerto Rico. The goal is to search for possible cores that orbit the white dwarfs near the Earth. "A bare core of what was a major planet is yet to be found. Magnetic signatures used to be a method to find these cores, but to no luck. Nor has one been found need a white dwarf," Veras said.
"Therefore, a discover that can be made through this would bring about something new. A "first" for all three methods of discovery in the planetary systems," Veras said.
The findings of this new study was published in the journal Monthly Notices of the Royal Astronomical Society.
