Astronomers are planning a hunt for relics of long-dead planets.
You've just found an important clue in this search: Dead Sea Planets May Send "Radiowaves" for Up to a Billion Years, A New Study by the Royal Astronomical Society.
The waves are created by interactions between the nucleus of a dead planet and the magnetic field of its dead star, the so-called white dwarf. After the explosion of a star, the surrounding planets are often freed of their atmosphere and their outer layers, leaving only the metallic inner core. This metal conducts electricity and creates a circuit between the planetary nucleus and the dead star, which generates radiation in the form of radio waves.
Scientists have known for decades that these planetary remains can send out radio waves. However, this is the first study that establishes a lifetime for these shipments, and it shows that the signals stop long enough for researchers on Earth to recognize and study them.
Alexander Wolszczan and Dimitri Veras, the scientists who made this discovery, next want to focus giant telescopes on white dwarf stars to search for radio broadcasts of undiscovered dead planets.
"No one has ever found only the very core of a large planet, nor a large planet, just by monitoring magnetic signatures or a large planet around a white dwarf," Wolszczan said in a news release. "Therefore, a discovery here would be 'first fruits' in three different senses for planetary systems."
Dead Planet Shipments
Wolszczan, astronomy professor at Penn State University, used radio waves to discover the first ever confirmed planet outside our solar system in the 1
For the current study, he wanted to determine how long radio broadcasts of dead planetary nuclei can last. So he and Veras computed computer simulations of the entire spectrum of magnetic fields and electrical conductivities observed in white dwarf stars.
Their results suggest that the metal cores of dead planets can emit radio waves for over 100 million years and sometimes as long as a billion years.
Linda Elkins-Tanton / YouTube
Stars die because they eventually burn their hydrogen and helium reserves. This fuel creates an internal pressure that keeps the size and shape of a star constant. But as soon as there is nothing left to burn, the star succumbs to gravity. Its core contracts and emits an energy wave that pushes its outer layers outward. When the star loses mass, its gravity weakens until it explodes and ejects its outer layers into space.
The hot, dense core of the star is left behind. In this phase he becomes a white dwarf.
The explosion is taking place nearby planets that blow up many in dust and tear others to shreds. The inner core of a planet will remain in orbit around its dead star at most.
"If a nucleus had reached this stage, it would eventually have been forcibly released from its atmosphere and its mantle and then thrown onto the White Dwarf," Veras said in the press release.
NASA / JPL-Caltech
Even our sun will die.
In about 5 billion years, our Sun will burn through its hydrogen core and begin the billion-year-long dying process, devouring the Earth before it goes out with a bang.  Finding and studying the distant remnants of dead planets from the past could help scientists learn about the possible fate of our own planet.
"Such a core could also provide insight into our own distant future and how the sunlight will eventually evolve," Veras said.
Researchers plan to use the results of their work to request observation time on ground-based telescopes such as Arecibo in Puerto Rico and the Green Bank Telescope in West Virginia. You've already identified the best white dwarf stars to test