<
https://theconversation.com/zombie-worlds-five-spooky-planets-orbiting-dead-stars-192447>
"All stars, including the Sun, have a finite lifetime. Stars shine by the
process of nuclear fusion in which lighter atoms, such as hydrogen, fuse
together to create heavier ones. This process releases vast quantities of
energy which counteracts the ever-present inward pull of the star’s gravity.
Ultimately, fusion helps stars to resist gravitational collapse.
This balance of forces is called “hydrostatic equilibrium”. However, there will
come a time when the supply of fuel in the core of a star starts to run out and
it eventually dies. Stars with more than about eight times the mass of the Sun
will typically burn through their fuel in less than 100 million years. Once
fusion ceases, the star collapses – generating a massive instantaneous final
burst of nuclear fusion which causes the star to explode as a supernova.
Supernovas release enough energy to outshine the entire galaxy in which they
occur. What’s left afterwards are collapsed, dead stellar cores called neutron
stars or, if the progenitor star was massive enough, a black hole. Any planets
orbiting a star when it goes supernova would be obliterated. Mysteriously
though, a handful of “zombie planets” have been detected orbiting neutron
stars. And they are some of the weirdest worlds in the cosmos.
Neutron stars are extremely dense, containing as much mass as the Sun squashed
into a sphere only a few miles across. Some neutron stars emit beams of radio
waves into space – and it is around these “pulsar” stars that planets have been
found. As the pulsar spins, its radio beams sweep through space generating
regular radio flashes. Pulsars were discovered in 1967 – you can listen to the
sounds of the radio emission from some of them here.
The regularity of these radio pulses make pulsars ideal for hunting nearby
planets. If a pulsar has a planet, they will both orbit a shared gravitational
centre. This means the radio emission will be periodically stretched and
compressed in a predictable fashion – allowing us to detect the planet."
Cheers,
*** Xanni ***
--
mailto:xanni@xanadu.net Andrew Pam
http://xanadu.com.au/ Chief Scientist, Xanadu
https://glasswings.com.au/ Partner, Glass Wings
https://sericyb.com.au/ Manager, Serious Cybernetics
