Some 4.5 billion years from today, our Sun will run out of fuel and shed its outer layers. In the process, it will destroy Mercury, Venus and probably Earth, and is expected to radiate enough high energy photons to evaporate Jupiter, Saturn, Uranus and Neptune.
What will remain of the Sun is called a “white dwarf”. Can any planet orbiting a star survive such an event? New evidence suggests it can.
Astronomers from the University of Warwick and the University of Valparaíso have reported the first indirect evidence of a giant planet orbiting a white dwarf star (WDJ0914+1914). It is the first time any such planet has been found. The study, in the journal Nature, suggests there could be many more planets around such white dwarf stars waiting to be discovered.
The Neptune-like planet orbits the white dwarf every ten days, and cannot be seen directly. The evidence is in the form of a disc of gas (hydrogen, oxygen and sulphur) formed from its evaporating atmosphere. Spikes of gas were detected by the Very Large Telescope of the European Southern Observatory in Chile.
The discovery is significant, because while there was growing evidence accumulated in the past two decades that planetary systems can survive into white dwarf stars, only smaller objects such as asteroids had been detected so far. This is the first evidence of an actual planet in such a system.
