A Jupiter-sized planet has been found orbiting a white dwarf star in the Milky Way, providing clues as to what will happen in our solar system when the sun finally dies.
An international team of astronomers observed the phenomenon, which forms when a star runs out of nuclear fuel to burn and dies.
The distant planet, a gas giant with a mass 1.4 times that of Jupiter, was able to survive the death of its host star.
Scientists say the discovery is in line with previous estimates that more than half of white dwarf stars may have similar giant planets orbiting them. Although the phenomenon had been predicted, it had never been observed before.
The first author of the study, Joshua Blackman of the University of Tasmania, said: “We predict that this planet has a distance [from the white dwarf] between 2.5 and six times the distance from the Earth to the sun, which is similar to that of Jupiter. “
Blackman said the discovery sheds light on what will happen when the sun runs out of fuel. “This is the first time we have found … a system that looks like what we hope will happen to our solar system in five to six billion years.”
In five billion years, the sun is expected to expand, becoming what is known as a red giant. “In this process where the sun turns into a red giant, it is likely to destroy the inner planets … Mercury and Venus are likely to be destroyed,” Blackman said. Earth may survive the event, but it will not be habitable.
Once the sun runs out of fuel completely, it will contract and become the cold corpse of a star – a white dwarf.
Themiya Nanayakkara, an astronomer at Swinburne University of Technology who was not involved in the research, said the discovery suggests that outer gas giant planets like Jupiter and Saturn could survive the death of the sun.
“Discard the theories of the past … that say you can’t have planets around white dwarfs,” Nanayakkara said.
The size of a star determines what it eventually becomes: the largest and heaviest stars can end up as black holes or neutron stars.
In the Milky Way, about 95% of all stars are destined to eventually become white dwarfs, Blackman said. “The universe is not old enough for that to have happened yet.”
White dwarfs emit only dim light, making them virtually impossible to observe directly from ground-based telescopes. Instead, the team found the dead star using a technique known as gravitational microlensing, where light from a distant planet, the Jupiter-sized gas giant, is deflected by gravity from a closer star – in this case, the dwarf. White.
The discovery was “completely fortuitous,” Blackman said. “We expected to see a normal star like our sun. So we spent quite a few years analyzing the data to try to determine if we made a mistake. “
Based on their observations, the team was able to rule out other possibilities for the dead star, such as a black hole or a neutron star.
The study was published in the journal Nature.
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