Dead Planets Can ‘Broadcast’ for Up to a Billion Years

Modelling led by University of Warwick determines that cores can survive for as long as a billion years after their stars have bured up their nuclear fuel.  (Image: via   pixabay  /  CC0 1.0)
Modelling led by University of Warwick determines that cores can survive for as long as a billion years after their stars have bured up their nuclear fuel. (Image: via pixabay / CC0 1.0)

Astronomers are planning to hunt for cores of exoplanets around white dwarf stars by “tuning in” to the radio waves that they emit. In new research led by the University of Warwick, scientists have determined the best candidate white dwarfs to start their search, based upon their likelihood of hosting surviving planetary cores and the strength of the radio signal that we can “tune in” to.

Published in the Monthly Notices of the Royal Astronomical Society, the research, led by Dr. Dimitri Veras from the Department of Physics, assesses the survivability of planets that orbit stars that have burned all of their fuel and shed their outer layers, destroying nearby objects and removing the outer layers of planets.

They have determined that the cores that result from this destruction may be detectable and could survive long enough to be found from Earth.

The first exoplanet confirmed to exist was discovered orbiting a pulsar by co-author Professor Alexander Wolszczan from Pennsylvania State University in the 1990s, using a method that detects radio waves emitted from the star.

The researchers plan to observe white dwarfs in a similar part of the electromagnetic spectrum in the hope of achieving another breakthrough.

The magnetic field between a white dwarf and an orbiting planetary core can form a unipolar inductor circuit, with the core acting as a conductor due to its metallic constituents. Radiation from that circuit is emitted as radio waves that can then be detected by radio telescopes on Earth. The effect can also be detected from Jupiter and its moon Io, which form a circuit of their own.

However, the scientists needed to determine how long those cores can survive after being stripped of their outer layers. Their modelling revealed that in a number of cases, planetary cores can survive for over 100 million years and as long as a billion years.

The astronomers plan to use the results in proposals for observation time on telescopes such as Arecibo in Puerto Rico and the Green Bank Telescope in West Virginia to try to find planetary cores around white dwarfs. Lead author Dr. Dimitri Veras, from the University of Warwick, said:

Professor Alexander Wolszczan, from Pennsylvania State University, said:

Dr. Veras added:

Provided by: University of Chicago Medicine [Note: Materials may be edited for content and length.]

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